Polyamide composite material and application thereof

Abstract

The invention provides a polyamide composite material and application thereof. The polyamide composite material comprises the following components in parts by mass: 35-82 parts of polyamide resin, 5-45 parts of a reinforcing material and 5-25 parts of an organic phosphonate flame retardant, the water-soluble acid value of the organic phosphonate flame retardant is 0.1 to 0.3 mg KOH / g. By adopting the organic phosphonate flame retardant with a low acid value, the generation of dialkyl phosphinic acid decomposed in a high-temperature process can be slowed down, so that the amount of mold scale generated in an injection molding process of the polyamide composite material is obviously reduced, and the injection molding production efficiency is improved; meanwhile, the polyamide composite material has the advantages that the content of water boiling precipitates is obviously reduced, the damp-heat-resistant stability is excellent, and the service life of the polyamide composite material under damp-heat conditions is prolonged.

Description

Technical Field

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

[0002] Polyamide, also known as nylon, contains repeated amide groups -NHCO- on its main chain. This group is polar, which allows strong hydrogen bonds to form between molecular chains. Therefore, polyamide has high crystallinity and excellent mechanical properties. It is a type of resin with the largest output, the most varieties, the widest range of uses, and the best overall performance among the five general-purpose engineering plastics.

[0003] Traditional flame-retardant nylon usually uses brominated flame retardants, but with the continuous improvement of environmental protection requirements, and with the release of the EU's ROHS directive on limiting and prohibiting the use of toxic substances and the WEEE directive on the treatment of waste electronic equipment, traditional brominated flame retardants can no longer meet the requirements of the EU ROHS and WEEE directives. Halogen-free flame-retardant nylon materials are in line with the development trend of green environmental protection, and are also a development trend requirement for flame-retardant nylon materials in the electronics and electrical industries. In the application fields of electronic and electrical materials, such as circuit breakers, connectors, and terminal blocks, halogen-free materials are required, and more and more customers not only have requirements for the flame retardant grade of the materials, but also have higher and higher requirements for the precipitation and service life of the materials.

[0004] As a general halogen-free flame retardant, dialkyl phosphinate not only has good flame retardant properties, small addition amount, and little effect on the physical and electrical properties of the base resin, but also has lower smoke emission than halogen flame retardants and higher CTI (comparative tracking index). Dialkyl phosphinate flame retardant polyamide has superior performance in both mechanical and electrical properties, and is increasingly favored by manufacturers in the electrical and electrical industry, with broad market prospects. However, with the continuous improvement of product performance requirements in the industry, the performance defects of dialkyl phosphinate flame retardant polyamide are gradually exposed. Since polyamide has more polar amide groups, it is easier to absorb water and has a higher water absorption rate. For example, the water absorption rate of polyamide 66 at 23°C and 50% humidity can reach 2.7%. The addition of dialkyl phosphinate exacerbates the water absorption problem of the material. In addition, Braun U et al. found that when dialkyl phosphinates are used to flame retard polyamide, during the extrusion process or high-temperature injection molding process, the dialkyl phosphinates are easily decomposed by heat to generate dialkyl phosphinate acidic substances, which further promote the decomposition of the system, resulting in a large amount of gas in the processing process; during repeated injection molding processes, serious mold deposits often appear on the mold, which not only affects the appearance of the product, but also requires frequent mold cleaning, resulting in low production efficiency, making it difficult to promote the use of the product.

[0005] Currently, the main method to solve the mold fouling problem in the injection molding of dialkyl phosphite flame-retardant polyamide materials is to add acid absorbents to the system to reduce the acidity of the system. For example, EP2417191A1 reduces the acidity of the system by adding calcium oxide to the system, which undergoes a neutralization reaction with acidic substances, thereby reducing the decomposition of the matrix resin and the corrosion of the mold during high-temperature injection molding; however, calcium oxide is prone to moisture absorption, which will exacerbate the moisture absorption problem of the polyamide system after addition, resulting in an increase in the water absorption rate and being difficult to control during the processing. CN112409786A prepares a halogen-free flame-retardant thermoplastic polyamide with lower mold fouling by adding a certain amount of ethylene copolymer to the system. CN114874616A prepares a halogen-free flame-retardant thermoplastic polyamide with more continuous mold opening and closing times (lower mold fouling) by adding metal oxides and a polyhydroxy system to the system. However, the methods of improving the acidity of the system and reducing mold fouling by adding external additives not only increase costs but also inevitably lead to problems such as a decline in other properties of the flame-retardant polyamide due to the addition of new substances. For example, the compatibility between the external additives and the matrix resin is poor, the addition of inorganic additives will reduce the mechanical properties of the material, the risk of additive precipitation is high, and the hygrothermal stability of the product is insufficient, etc.

[0006] Therefore, developing a flame-retardant polyamide material that can achieve low mold fouling, less additive precipitation, and good hygrothermal resistance without the aid of other additives is the research focus in this field. Summary of the Invention

[0007] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a polyamide composite material and its application. By using an organic phosphonate flame retardant with a low acid value, the mold fouling amount of the polyamide composite material is significantly reduced, the content of water-boiled precipitates is small, the hygrothermal resistance is good, and its service life under hygrothermal conditions is extended.

[0008] To achieve this purpose, the present invention adopts the following technical solutions:

[0009] In the first aspect, the present invention provides a polyamide composite material, which comprises the following components in parts by mass:

[0010] Polyamide resin 35 - 82 parts

[0011] Reinforcing material 5 - 45 parts

[0012] Organic phosphonate flame retardant 5 - 25 parts;

[0013] The water-soluble acid value of the organic phosphonate flame retardant is 0.1 - 0.3 mg KOH / g.

[0014] The present invention uses an organic phosphonate flame retardant with a low acid value, which can slow down the generation of dialkyl phosphinic acid decomposed during the high-temperature process, enabling the polyamide composite material to have a small amount of mold scale generated during the injection molding process without adding other acid-absorbing / adsorbing additives, thereby improving the injection molding production efficiency and the appearance of the product. At the same time, the polyamide composite material has a significantly reduced content of water-boiled precipitates (i.e., less precipitation of the flame retardant), good heat and humidity resistance stability, and an extended service life under humid and hot conditions.

[0015] The following are the preferred technical solutions of the present invention, but do not limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the objectives and beneficial effects of the present invention can be better achieved and realized.

[0016] In the polyamide composite material of the present invention, the mass fraction of the polyamide resin is 35 - 82 parts, for example, it can be 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts or 80 parts, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range.

[0017] The mass fraction of the reinforcing material is 5 - 45 parts, for example, it can be 8 parts, 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, 22 parts, 25 parts, 28 parts, 30 parts, 32 parts, 35 parts, 38 parts, 40 parts, 42 parts or 44 parts, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range.

[0018] The mass fraction of the organic phosphonate flame retardant is 5 - 25 parts, for example, it can be 6 parts, 8 parts, 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, 22 parts or 24 parts, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range.

[0019] The water-soluble acid value of the organic phosphonate flame retardant is 0.1 - 0.3 mg KOH / g, for example, it can be 0.11 mg KOH / g, 0.12 mg KOH / g, 0.15 mg KOH / g, 0.18 mg KOH / g, 0.2 mg KOH / g, 0.22 mg KOH / g, 0.25 mg KOH / g, 0.28 mg KOH / g or 0.29 mg KOH / g, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range.

[0020] Exemplarily, the water-soluble acid value of the organic phosphonate flame retardant can be obtained by the following method: 1 g of the sample to be tested is evenly wetted with ethanol (the mass of ethanol is m 乙醇 ), and then water (the mass of water is m 水 ) is added. After boiling in a sealed state at 90 °C for 1 h, it is cooled to 25 °C and kept at a constant temperature for 30 min, and the ethanol aqueous solution is replenished to the total mass before boiling; filtered, the mass of the clear filtrate is m 1 . The test acid value of the clear filtrate is measured by the potentiometric titration test method, and the blank acid value of (m 水 + m 乙醇 ) is measured by the potentiometric titration test method. Among them, the concentration of the potassium hydroxide solution used in the titration is 0.05 mol / L, and the water-soluble acid value = test acid value × (m 水 + m 乙醇 ) / m 1 - blank acid value.

[0021] In the present invention, the polyamide includes any one or a combination of at least two of the condensation products of dicarboxylic acids and diamines, the condensation products of ω-amino acids, and the ring-opening polymerization products of cyclic lactams. The dicarboxylic acids exemplarily include, but are not limited to, any one or a combination of at least two of adipic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, terephthalic acid, and isophthalic acid. The diamines exemplarily include, but are not limited to, any one or a combination of at least two of butanediamine, pentanediamine, hexanediamine, octanediamine, nonanediamine, decanediamine, dodecanediamine, p-phenylenediamine, and m-phenylenediamine. The cyclic lactams exemplarily include, but are not limited to, any one or a combination of at least two of caprolactam, octanolactam, undecanolactam, and dodecanolactam. The ω-amino acids exemplarily include, but are not limited to, any one or a combination of at least two of the ω-amino acids formed by the ring-opening of the foregoing cyclic lactams and aminobenzoic acid.

[0022] Preferably, the polyamide resin includes any one or a combination of at least two of polyamide 6 (polycaprolactam), polyamide 11 (polyundecanolactam), polyamide 12 (polydodecanolactam), polyamide 66 (polyhexamethylene adipamide), polyamide 46 (polybutylene adipamide), polyamide 610 (polyhexamethylene sebacamide), polyamide 611 (polyundecanedioyl decanediamide), polyamide 612 (polydodecanedioyl decanediamide), polyamide 1010 (polydecamethylene sebacamide), polyamide 6T (polyhexamethylene terephthalamide), polyamide 9T (polynonamethylene terephthalamide), and polyamide 10T (polydecamethylene terephthalamide).

[0023] Preferably, the reinforcing material includes any one or a combination of at least two of glass fiber, carbon fiber, aramid fiber, asbestos fiber, wollastonite fiber, ceramic fiber, potassium titanate whisker, basic magnesium sulfate whisker, silicon carbide whisker, aluminum borate whisker, and glass fiber is further preferred.

[0024] Preferably, the glass fiber includes any one or a combination of at least two of E-glass fiber (alkali-free glass fiber), C-glass fiber (medium-alkali glass fiber), A-glass fiber (high-alkali glass fiber), AR-glass fiber (alkali-resistant glass fiber), S-glass fiber (special glass fiber), D-glass fiber (low-dielectric glass fiber), and quartz glass fiber.

[0025] Preferably, the diameter of the glass fiber is 0.1-30 μm, for example, it can be 0.5 μm, 1 μm, 2 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 22 μm, 25 μm or 28 μm, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range, and 5-20 μm is further preferred.

[0026] Preferably, the organic phosphonate flame retardant includes the following components by mass parts:

[0027]

[0028] The mass parts of diethyl phosphite in the organic phosphonate flame retardant are 95-99.88 parts, for example, it can be 95.5 parts, 96 parts, 96.2 parts, 96.5 parts, 96.8 parts, 96.9 parts, 97 parts, 97.2 parts, 97.5 parts, 97.8 parts, 98 parts, 98.2 parts, 98.5 parts, 98.8 parts, 99 parts, 99.2 parts, 99.5 parts, 99.6 parts or 99.8 parts, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range.

[0029] Preferably, the mass percentage content of diethyl phosphite in the organic phosphonate flame retardant is ≥94%, for example, it can be 94.5%, 95%, 95.5%, 96%, 96.2%, 96.5%, 96.8%, 97%, 97.2%, 97.5%, 97.8%, 98%, 98.2%, 98.5%, 98.8%, 99%, 99.2%, 99.5%, 99.8% or 99.8%, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range.

[0030] The mass fraction of ethyl butyl phosphinate in the organic phosphonate flame retardant is 0.1 - 3 parts, for example, it can be 0.12 parts, 0.15 parts, 0.2 parts, 0.25 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.2 parts, 2.5 parts, 2.7 parts, 2.8 parts or 2.9 parts, and the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range.

[0031] The mass fraction of ethyl phosphonate in the organic phosphonate flame retardant is 0.01 - 1 part, for example, it can be 0.02 parts, 0.05 parts, 0.1 parts, 0.15 parts, 0.2 parts, 0.25 parts, 0.3 parts, 0.35 parts, 0.4 parts, 0.45 parts, 0.5 parts, 0.55 parts, 0.6 parts, 0.65 parts, 0.7 parts, 0.75 parts, 0.8 parts, 0.85 parts, 0.9 parts or 0.95 parts, and the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range.

[0032] The mass fraction of monoethyl phosphinate in the organic phosphonate flame retardant is 0.01 - 1 part, for example, it can be 0.02 parts, 0.05 parts, 0.1 parts, 0.15 parts, 0.2 parts, 0.25 parts, 0.3 parts, 0.35 parts, 0.4 parts, 0.45 parts, 0.5 parts, 0.55 parts, 0.6 parts, 0.65 parts, 0.7 parts, 0.75 parts, 0.8 parts, 0.85 parts, 0.9 parts or 0.95 parts, and the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range.

[0033] Exemplarily, the mass fractions of diethyl phosphinate, ethyl butyl phosphinate, ethyl phosphonate, and monoethyl phosphinate in the organic phosphonate flame retardant can be analyzed and tested by liquid chromatography. For example, the sample to be tested is dissolved in a sulfuric acid aqueous solution (mass concentration 30%) five times the mass of the sample, and then diluted 10 - 30 times with the mobile phase for analysis and testing; the mobile phase is a mixture of water and methanol with a mass ratio of 9:1, added with trifluoroacetic acid with a volume content of 0.5%, using a ShimNexCS C18 chromatographic column, and the flow rate is 0.6 mL / min; the mass content of each component is calculated by the area normalization method.

[0034] Preferably, the cations in the diethyl phosphinate, ethyl butyl phosphinate, ethyl phosphonate, and monoethyl phosphinate independently include Al 3+ 、Ca 2+ 、Cu 2+ 、Zn 2+ 、Fe2+ , Fe 3+ , Ti 4+ Any one or a combination of at least two of them, and further preferably Al 3+ .

[0035] Preferably, the organophosphonate flame retardant further includes alkali-insoluble substances, and the alkali-insoluble substances include any one or a combination of at least two of hydroxides, oxides, phosphates, pyrophosphates, polyphosphates, and phosphites.

[0036] Preferably, the alkali-insoluble substances include any one or a combination of at least two of aluminum hydroxide, aluminum oxide, aluminum phosphate, aluminum pyrophosphate, aluminum polyphosphate, and aluminum phosphite.

[0037] Preferably, the mass portion of the alkali-insoluble substances in the organophosphonate flame retardant is ≤ 3 parts, and for example, it can be 0, 0.01 part, 0.02 part, 0.05 part, 0.08 part, 0.1 part, 0.15 part, 0.2 part, 0.25 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.8 part, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.2 parts, 2.5 parts or 2.8 parts, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range.

[0038] Exemplarily, the mass portion of the alkali-insoluble substances in the organophosphonate flame retardant is obtained by the following method: mixing the sample to be tested with an aqueous sodium hydroxide solution (mass concentration 3%) at a mass ratio of 1:100, stirring at 35 °C for 30 min, filtering with a filter paper with a precision ≤ 2 μm, rinsing with water 3 times, drying the filter paper and weighing it. The mass increase relative to the filter paper before filtration (dry filter paper) is the mass of the insoluble substances, and the ratio of the mass of the insoluble substances to the mass of the sample to be tested is the mass content of the alkali-insoluble substances.

[0039] Preferably, the organophosphonate flame retardant further includes other phosphorus-containing compounds, and the mass portion of the other phosphorus-containing compounds in the organophosphonate flame retardant is ≤ 1 part, and for example, it can be 0, 0.01 part, 0.05 part, 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part or 0.95 part, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range. Further preferably, it is 0.05 - 0.4 parts.

[0040] It should be noted that the other phosphorus-containing compounds are alkali-soluble phosphorus-containing substances different from diethyl phosphinate, ethyl butyl phosphinate, ethyl phosphonate, and monoethyl phosphinate. Their mass fraction can be measured by phosphorus nuclear magnetic resonance spectroscopy. In the phosphorus nuclear magnetic resonance spectrum, the integral area of other peaks except diethyl phosphinate, ethyl butyl phosphinate, ethyl phosphonate, and monoethyl phosphinate represents the content of the other phosphorus-containing compounds.

[0041] Preferably, the organic acid value of the organic phosphonate flame retardant is ≤0.05 mg KOH / g, and can be, for example, 0.001 mg KOH / g, 0.005 mg KOH / g, 0.008 mg KOH / g, 0.01 mg KOH / g, 0.02 mg KOH / g, 0.025 mg KOH / g, 0.028 mg KOH / g, 0.03 mg KOH / g, 0.032 mg KOH / g, 0.035 mg KOH / g, 0.038 mg KOH / g, 0.04 mg KOH / g, or 0.045 mg KOH / g, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range. Further preferably, it is 0.001 - 0.04 mg KOH / g.

[0042] Exemplarily, the organic acid value of the organic phosphonate flame retardant can be measured by the following method: After uniformly wetting 1 g of the sample to be tested with dichloromethane (the mass of dichloromethane is m 二氯甲烷 ), it is boiled in a sealed manner at 90 °C for 1 h, then cooled to 25 °C and kept at a constant temperature for 30 min, and dichloromethane is added to make up the total mass before boiling; after filtration, the mass of the clear filtrate is m 1 , the acid value of the clear filtrate is measured by potentiometric titration, and the blank acid value of the weight m 二氯甲烷 is measured by potentiometric titration. The concentration of the potassium hydroxide solution used in the titration is 0.05 mol / L, and the organic acid value = test acid value × m 二氯甲烷 / m 1 - blank acid value.

[0043] Preferably, the mass content of sulfate in the organic phosphonate flame retardant is 100 - 500 ppm, and can be, for example, 120 ppm, 150 ppm, 200 ppm, 250 ppm, 270 ppm, 300 ppm, 350 ppm, 400 ppm, 420 ppm, 450 ppm, or 480 ppm, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range. Further preferably, it is 110 - 430 ppm.

[0044] Exemplarily, the mass content of sulfate radical in the organic phosphonate flame retardant is obtained by testing with external standard method using ion chromatography technology according to the method in the standard EN 14582:2007 - Determination of halogen content.

[0045] Preferably, the D 50 particle size of the organic phosphonate flame retardant is 1 - 100 μm, for example, it can be 10 μm, 20 μm, 30 μm, 33 μm, 35 μm, 38 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 95 μm, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the specific point values included in the scope of the present invention are not exhaustively listed herein. Further preferably, it is 20 - 60 μm.

[0046] The D 50 particle size of the organic phosphonate flame retardant is the particle size corresponding to the cumulative volume distribution percentage of 50%, and it can be determined by using a laser particle size analyzer with reference to the standard GB / T 19077 - 2016 Laser diffraction method for particle size distribution.

[0047] Preferably, the moisture content of the organic phosphonate flame retardant is ≤ 1 wt%, for example, it can be 0, 0.01 wt%, 0.02 wt%, 0.05 wt%, 0.08 wt%, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt% or 0.9 wt%, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the specific point values included in the scope of the present invention are not exhaustively listed herein. Further preferably, it is 0.05 - 0.3 wt%.

[0048] Exemplarily, the moisture content of the organic phosphonate flame retardant can be obtained by testing with an infrared moisture analyzer, for example, using the MA 35 infrared moisture analyzer of Sartorius in Germany. After the sample is placed at 120 °C for 30 min, the water content is automatically tested.

[0049] Preferably, the phosphorus content of the organic phosphonate flame retardant is 22 - 25 wt%, for example, it can be 22.2 wt%, 22.5 wt%, 22.8 wt%, 23 wt%, 23.2 wt%, 23.5 wt%, 23.8 wt%, 24 wt%, 24.2 wt%, 24.5 wt% or 24.8 wt%, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the specific point values included in the scope of the present invention are not exhaustively listed herein.

[0050] Exemplarily, the phosphorus content of the organic phosphonate flame retardant can be tested by the following method: Dissolve the sample to be tested with an aqueous sulfuric acid solution (mass concentration 30%), and test it with reference to the standard GB / T 11893-1989 "Water Quality - Determination of Total Phosphorus - Ammonium Molybdate Spectrophotometric Method".

[0051] It should be noted that the polymer composition of the present invention may further include any other additives, other auxiliaries, etc. that are motivated to be added in the art.

[0052] Preferably, the polyamide composite further includes 1-15 parts by mass of a melamine-based flame retardant. The mass parts of the melamine-based flame retardant can be 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts or 14 parts, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.

[0053] Preferably, the melamine-based flame retardant includes any one or a combination of at least two of melamine polyphosphate salt, melamine pyrophosphate salt, piperazine pyrophosphate, melem polyphosphate salt, melem pyrophosphate salt, melem phosphate salt, melem diethylphosphinate salt, melem ethylphosphinate salt, melem phosphite salt, and melem alkylphosphonate salt.

[0054] Preferably, the mass ratio of the organic phosphonate flame retardant to the melamine-based flame retardant is 1:(0.1-3), for example, it can be 1:0.2, 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, 1:2.2, 1:2.5, 1:2.8, etc., and further preferably 1:(0.2-1).

[0055] Preferably, the polyamide composite further includes any one or a combination of at least two of a synergistic flame retardant, an antioxidant, and a lubricant.

[0056] Preferably, the synergistic flame retardant includes any one or a combination of at least two of zinc borate, zinc stannate, zinc sulfide, and boehmite.

[0057] Preferably, the mass parts of the synergistic flame retardant in the polyamide composite ≤ 5 parts. The synergistic flame retardant can be 0, 0.1 part, 0.2 part, 0.5 part, 0.8 part, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts or 4.5 parts, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.

[0058] Preferably, the polyamide composite further comprises 0.01-1 part of antioxidant by mass. The mass of the antioxidant can be 0.05 part, 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part or 0.9 part, as well as specific point values between the above point values. Due to space limitations and for the sake of brevity, the specific point values included in the scope of the present invention are not exhaustively listed herein.

[0059] Preferably, the antioxidant includes any one or a combination of at least two of hindered amine antioxidants, hindered phenol antioxidants, phosphite antioxidants, and thioester antioxidants.

[0060] Exemplarily, the antioxidant includes any one or a combination of at least two of pentaerythritol tetra(β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), n-octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, N,N'-bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine, tris(2,4-di-tert-butylphenyl)phosphite, 2,6-di-tert-butyl-p-cresol, distearyl β,β-thiodipropionate, 2,4-dioctylthiomethyl-6-tert-butylphenol, 2,6-di-tert-butyl-4-methoxyphenol, tocopherol, 2,2'-thiobis(6-tert-butyl-4-methylphenol), 2,2'-thiobis(4-octylphenol), 4,4'-thiobis(6-tert-butyl-3-methylphenol), 4,4'-thiobis(6-tert-butyl-2-methylphenol), 4,4'-thiobis(3,6-di-sec-amylphenol), 4,4'-bis(2,6-dimethyl-4-hydroxyphenyl)disulfide, 2,2'-methylenebis(6-tert-butyl-4-methylphenol), 3,5,3',5'-tetra-tert-butyl-4,4'-dihydroxydibenzyl ether, bis(octadecyl)-2,2-bis(3,5-di-tert-butyl-2-hydroxybenzyl)malonate, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, 1,4-bis(3,5-di-tert-butyl-4-hydroxybenzyl)-2,3,5,6-tetramethylbenzene, 2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)phenol, 2,4-dioctylthio-6-(3,5-di-tert-butyl-4-hydroxyanilino)-1,3,5-triazine, dimethyl 2,5-di-tert-butyl-4-hydroxybenzylphosphonate, 4-hydroxylauramide, 4-hydroxystearanilide, octyl N-(3,5-di-tert-butyl-4-hydroxyphenyl)carbamate, β-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionate alcohol ester, β-(3,5-dicyclohexyl-4-hydroxyphenyl)propionate alcohol ester, 3,5-di-tert-butyl-4-hydroxyphenylacetic acid alcohol ester, N,N'-bis(3,5-di-tert-butyl-4-hydroxybenzoyl)hexamethylenediamine, N,N'-bis(3,5-di-tert-butyl-4-hydroxybenzoyl)trimethylenediamine, N,N'-bis(3,5-di-tert-butyl-4-hydroxybenzoyl)hydrazine.

[0061] Preferably, the polyamide composite further includes 0.01 - 1 part of lubricant by mass. The mass of the lubricant can be 0.05 part, 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part or 0.9 part, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the specific point values included in the scope of the present invention are not exhaustively listed herein.

[0062] Preferably, the lubricant includes any one or a combination of at least two of ester lubricants, alcohol lubricants, hydrocarbon lubricants, fatty acid lubricants, fatty acid amide lubricants, and metal soap lubricants.

[0063] Preferably, the polyamide composite material further includes any one or a combination of at least two of fillers, colorants, and ultraviolet absorbers.

[0064] Preferably, the filler includes any one or a combination of at least two of silica, aluminum silicate, silicon oxide, calcium carbonate, titanium oxide, talc, wollastonite, diatomaceous earth, clay, kaolin, spherical glass, mica, gypsum, iron oxide, magnesium oxide, and zinc oxide.

[0065] Preferably, the colorant includes inorganic colorants and / or organic colorants; depending on its solubility and coloring properties, the colorant may include pigments and / or dyes.

[0066] Exemplarily, the colorant includes any one or a combination of at least two of titanium dioxide, ultramarine blue, iron oxide, zinc sulfide, carbon black, phthalocyanine, quinacridone, perylene black, and aniline black.

[0067] Preferably, the ultraviolet absorber includes any one or a combination of at least two of hydroxybenzoate ultraviolet absorbers, benzophenone ultraviolet absorbers, benzotriazole ultraviolet absorbers, substituted acrylonitrile ultraviolet absorbers, triazine ultraviolet absorbers, and hindered amine ultraviolet absorbers.

[0068] Exemplarily, the ultraviolet absorber includes any one or a combination of at least two of hexadecyl 3,5 - diisobutyl - 4 - hydroxybenzoate, 2,4 - di - tert - butylphenyl 3,5 - di - tert - butyl - 4 - hydroxybenzoate, n - hexadecyl 3,5 - di - tert - butyl - 4 - hydroxybenzoate, 2 - hydroxy - 4 - alkoxydibenzophenone, 1,3 - bis(methoxy - 3 - hydroxy - 4 - dibenzoyl)benzene, 2 - hydroxy - 4 - phenylalkoxydibenzophenone, 2 - hydroxy - 4 - n - octyloxydibenzophenone, 2 - hydroxy - 4 - methacryloyloxydibenzophenone, 2 - (2'-hydroxy - 5'-methylphenyl)benzotriazole, 2 - (2'-hydroxy - 5'-methyl) - benzotriazole, 2 - (3',5'-di - tert - butyl - 2'-hydroxy) - benzotriazole, 2 - (2'-hydroxy - 3'-isobutyl - 5'-tert - butyl) - benzotriazole, 2 - (2'-hydroxy - 3',5'-bis(1,1 - dimethylphenyl)) - benzotriazole, 2 - (2'-hydroxy - 5'-tert - octyl) - benzotriazole, 2 - (2'-hydroxy - 3'-(1,1 - dimethylphenyl) - 5'-(1,1,3,3 - tetramethylbutyl)) - benzotriazole, 2,2'-methylene - bis(6 - (2H - benzotriazol - 2 - yl) - 4 - tert - octyl)phenol, 2 - (2H - benzotriazol - 2 - yl) - 4,6 - bis(1 - methyl - 1 - phenylethyl)phenol, bis(2,2,6,6 - tetramethylpiperidin - 4 - yl) sebacate, N,N' - (2,2,6,6 - tetramethyl - 4 - aminopiperidin) - isophthalamide, bis(1 - octyloxy - 2,2,6,6 - tetramethylpiperidin - 4 - yl) sebacate, (1,2,2,6,6 - pentamethylpiperidin - 4 - yl) methacrylate.

[0069] Preferably, the mass parts of the filler in the polyamide composite material ≤ 40 parts, for example, it can be 0, 0.1 part, 0.5 part, 1 part, 2 parts, 5 parts, 8 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts or 38 parts, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range.

[0070] In a preferred technical solution, the polyamide composite material includes the following components by mass parts:

[0071]

[0072] The polyamide resin is used as the matrix material. Preferably, the mass percentage content of the polyamide resin in the polyamide composite material is 35% - 82%, for example, it can be 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or 80%, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range.

[0073] The reinforcing material can regulate the mechanical properties of the polyamide composite material and achieve the reinforcement effect. Preferably, the mass percentage content of the reinforcing material in the polyamide composite material is 5%-45%, for example, it can be 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42% or 44%, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range.

[0074] Preferably, the mass percentage content of the organophosphonate flame retardant in the polyamide composite material is 5%-25%, for example, it can be 6%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32% or 34%, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range.

[0075] Preferably, the boiling water phosphorus content of the polyamide composite material is ≤510 ppm, for example, it can be 360 ppm, 380 ppm, 400 ppm, 420 ppm, 450 ppm, 480 ppm, 500 ppm, 505 ppm or 508 ppm, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range. Further preferably, it is 370-507 ppm.

[0076] Exemplarily, the boiling water phosphorus content of the polyamide composite material is measured by the following method: The polyamide composite material to be tested is placed in boiling water at 90°C for 1 h, cooled to room temperature, filtered, and the phosphorus content in the filtrate is measured by the molybdate ammonium spectrophotometric method of GB / T 11893-1989.

[0077] Preferably, the injection mold scale of the polyamide composite material is ≤7.5 mg, for example, it can be 3.5 mg, 3.8 mg, 4 mg, 4.2 mg, 4.5 mg, 4.8 mg, 5 mg, 5.2 mg, 5.5 mg, 5.8 mg, 6 mg, 6.2 mg, 6.5 mg, 6.8 mg, 7 mg, 7.2 mg or 7.4 mg, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range. Further preferably, it is 4-7.2 mg.

[0078] Exemplarily, the injection mold scale of the polyamide composite material is measured by the following method: Using an injection molding machine, the polyamide composite material is continuously injection molded 150 times at injection molding temperatures of 290°C, 285°C, 280°C, and 260°C. The mold scale sample in the finally collected mold is taken and weighed to obtain the mass of the injection mold scale.

[0079] In a second aspect, the present invention provides a method for preparing a polyamide composite material as described in the first aspect, the preparation method comprising: melt-blending a polyamide resin, a reinforcing material, and an organic phosphonate flame retardant and then extruding to obtain the polyamide composite material.

[0080] Preferably, the preparation method comprises the following steps:

[0081] Mix the polyamide resin and the organic phosphonate flame retardant to obtain a premix;

[0082] Melt-blend the premix and the reinforcing material and then extrude to obtain the polyamide composite material;

[0083] Preferably, the mixed materials further include any one or a combination of at least two of a melamine-based flame retardant, a synergistic flame retardant, an antioxidant, and a lubricant.

[0084] Preferably, the melt-blending is carried out in a screw extruder.

[0085] Preferably, the screw extruder is a twin-screw extruder.

[0086] Preferably, the temperature of the screw extruder is 180 - 330 °C, for example, it can be 190 °C, 200 °C, 210 °C, 220 °C, 230 °C, 240 °C, 250 °C, 260 °C, 270 °C, 280 °C, 290 °C, 300 °C, 310 °C or 320 °C, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the range.

[0087] Preferably, after the extrusion, it further includes the steps of pelletizing and drying.

[0088] In a third aspect, the present invention provides an application of the polyamide composite material as described in the first aspect in electronic appliances, electrical product components, energy storage devices, connectors, or automotive parts.

[0089] Preferably, the polyamide composite material is applied to plug connectors, energized components in distributors, circuit boards, potting materials, power plugs, safety switches, lamp shades, LED housings, capacitor housings, coil tubes, fans, protective contacts, cables, circuit boards, charger connection wires, engine covers, fabric coatings, vehicle seats, connector housings, circuit breaker housings, contactor housings, or electromagnetic switches.

[0090] Compared with the prior art, the present invention has the following beneficial effects:

[0091] In the polyamide composite material provided by the present invention, by using an organic phosphonate flame retardant with a low acid value, the occurrence of dialkyl phosphinic acid decomposed during the high-temperature process can be slowed down, the amount of mold scale generated during the injection molding process of the polyamide composite material is significantly reduced, thereby improving the injection molding production efficiency and the appearance of the product; at the same time, the polyamide composite material has a significantly reduced content of water-boiled precipitates, excellent heat and humidity resistance stability, and extends its service life under humid and hot conditions. Specific Embodiments

[0092] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0093] In a specific embodiment, the preparation method of the organic phosphonate flame retardant includes the following Method I or Method II.

[0094] Method I includes the following steps:

[0095] (A1) An aqueous solution of hypophosphite and an antioxidant undergo a free radical reaction with ethylene in the presence of an initiator to obtain an aqueous solution of diethyl phosphinate;

[0096] (A2) The aqueous solution of diethyl phosphinate obtained in step (A1), an aqueous solution of metal salt and an alkali solution are mixed and reacted under the condition of a pH value of 3.5 - 3.8 to obtain a slurry of metal diethyl phosphinate;

[0097] (A3) The slurry of metal diethyl phosphinate obtained in step (A2) and a flocculant are mixed and stirred to obtain a flocculate of metal diethyl phosphinate; the flocculate of metal diethyl phosphinate is filtered, washed and dried to obtain the organic phosphonate flame retardant.

[0098] Method II includes the following steps:

[0099] (B1) Hypophosphorous acid aqueous solution and an antioxidant undergo a free radical reaction with ethylene under the action of an initiator to obtain an aqueous solution of diethyl phosphinic acid;

[0100] (B2) The aqueous solution of diethyl phosphinic acid obtained in step (B1) reacts with sulfuric acid and metal hydroxide, and then an alkali solution is added to obtain a slurry of diethyl phosphinate with a pH value of 3.8 - 4.2;

[0101] (B3) The slurry of diethyl phosphinate obtained in step (B2) and a flocculant are mixed and stirred to obtain a flocculate of diethyl phosphinate; the flocculate of diethyl phosphinate is filtered, washed and dried to obtain the organic phosphonate flame retardant.

[0102] In a specific embodiment of the present invention, a preparation method of an organic phosphonate flame retardant is designed. Through the design of materials such as antioxidants and flocculants, the design of process steps and process parameters such as pH, and their combined action, the organic phosphonate flame retardant with a low acid value is prepared. When used in a polyamide composite material, it can reduce mold scale and make the polyamide composite material have a lower content of water-boiled out substances, greatly improving its hygrothermal stability and service life under hygrothermal conditions.

[0103] In a preferred specific embodiment, each of the antioxidants in step (A1) and step (B1) independently includes any one or a combination of at least two of hindered phenol antioxidants, hindered amine antioxidants, phosphite antioxidants, and thioester antioxidants, preferably any one or a combination of at least two of hindered phenol antioxidants, phosphite antioxidants, and thioester antioxidants.

[0104] In a preferred specific embodiment, each of the antioxidants in step (A1) and step (B1) independently includes any one or a combination of at least two of pentaerythritol tetrakis(β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (antioxidant 1010), n-octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1076), N,N'-bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine (antioxidant 1098), tris(2,4-di-tert-butylphenyl) phosphite (antioxidant 168), 2,6-di-tert-butyl-p-cresol (antioxidant BHT), distearyl thiodipropionate (antioxidant DSTP), antioxidant 215, and antioxidant 225.

[0105] The antioxidant can be a single component, such as any one of the above-listed antioxidants, or a composite antioxidant composed of multiple components in combination, such as a combination of a hindered phenol antioxidant and a phosphite antioxidant. A typical combination is a compound of antioxidant 1010 and antioxidant 168 in different proportions, such as antioxidant 215, antioxidant 225, etc.

[0106] In a preferred specific embodiment, each of the initiators in step (A1) and step (B1) independently includes any one or a combination of at least two of organic peroxides, persulfates, azo initiators, and photoinitiators.

[0107] In a preferred embodiment, the organic peroxide includes any one or a combination of at least two of diisobutyryl peroxide, benzoyl peroxide, bis(2-ethylhexyl) peroxydicarbonate, diisopropyl peroxydicarbonate, tert-butyl 1,1,3,3-tetramethylbutyl perpivalate, tert-butyl perpivalate, tert-pentyl perpivalate, dilauroyl peroxide, bis(3,3,5-trimethylacetyl) peroxide, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, 1,1,3,3-tetramethylbutyl 2-ethylhexanoate peroxide, bis(4-methylbenzoyl) peroxide, tert-pentyl 2-ethylhexanoate peroxide, tert-butyl 2-ethylhexanoate peroxide, tert-butyl isobutyrate peroxide, 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, 1,1-di-tert-pentylperoxycyclohexane, 1,1-di-tert-butylperoxycyclohexane, di-tert-butyl peroxide, di-tert-pentyl peroxide, dicumyl peroxide, 2,5-di-tert-butylperoxy-2,5-dimethylhexane, tert-butyl peracetate, tert-pentyl perbenzoate, tert-butyl maleate peroxide, tert-butyl 2-ethylhexyl carbonate peroxide.

[0108] In a preferred embodiment, the persulfate includes any one or a combination of at least two of sodium persulfate, potassium persulfate, and ammonium persulfate.

[0109] In a preferred embodiment, the azo initiator includes any one or a combination of at least two of azobisisobutyronitrile, azobisisoheptonitrile, azobis(isobutylamidine) hydrochloride, azobis(isobutylimidazoline) hydrochloride, and azoisobutyronitrile formamide.

[0110] It should be noted that the present invention has no special restrictions on the specific selection of the photoinitiator, and commonly used photoinitiators in the art are applicable.

[0111] In a preferred embodiment, the flocculants in step (A3) and step (B3) each independently include any one or a combination of at least two of polyacrylamide flocculants, starch flocculants, and chitin flocculants, more preferably polyacrylamide flocculants, and further preferably anionic polyacrylamide and / or non-ionic polyacrylamide.

[0112] In Method I, the hypophosphite preferably includes sodium hypophosphite and / or potassium hypophosphite, and an aqueous solution of sodium diethylphosphite and / or potassium diethylphosphite is obtained therefrom.

[0113] It should be noted that the hypophosphite can be anhydrous hypophosphite and / or hypophosphite hydrate.

[0114] In a preferred embodiment, the hypophosphite is sodium hypophosphite, and the solution obtained in step (A1) is an aqueous solution of sodium diethylphosphinate.

[0115] In a preferred embodiment, the mass percentage of hypophosphite in the hypophosphite aqueous solution of step (A1) is 10-60%, for example, it can be 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50% or 55%, etc., and more preferably 30-40%.

[0116] In a preferred embodiment, the mass ratio of the hypophosphite to the antioxidant in step (A1) is 100:(0.02-1.2), for example, it can be 100:0.04, 100:0.05, 100:0.06, 100:0.08, 100:0.1, 100:0.2, 100:0.3, 100:0.4, 100:0.5, 100:0.6, 100:0.7, 100:0.8, 100:0.9, 100:0.95, 100:1, 100:1.05, 100:1.1 or 100:1.15, and more preferably 100:(0.05-1).

[0117] In a preferred embodiment, the mass ratio of the hypophosphite to the initiator in step (A1) is 100:(0.1-5), for example, it can be 100:0.2, 100:0.5, 100:1, 100:1.5, 100:2, 100:2.5, 100:3, 100:3.5, 100:4, 100:4.5 or 100:4.8, etc.

[0118] It should be noted that the initiator in step (A1) can be added all at once, in batches, or continuously during the reaction; and a portion of the initiator in step (A1) can be added in advance, and the rest can be added continuously during the reaction.

[0119] In a preferred embodiment, the molar ratio of ethylene to hypophosphite in step (A1) is (2-2.1):1, for example, it can be 2.01:1, 2.02:1, 2.04:1, 2.05:1, 2.06:1, 2.08:1 or 2.09:1, etc.

[0120] In a preferred embodiment, the free radical reaction in step (A1) is carried out in a protective atmosphere.

[0121] In a preferred embodiment, the protective atmosphere includes nitrogen atmosphere and / or argon atmosphere.

[0122] In a preferred embodiment, the temperature of the radical reaction in step (A1) is 70 - 120 °C, for example, it can be 75 °C, 80 °C, 85 °C, 90 °C, 95 °C, 100 °C, 105 °C, 110 °C or 115 °C, etc. More preferably, it is 80 - 110 °C, and further preferably 90 - 105 °C.

[0123] The radical reaction in step (A1) is carried out in the presence of an initiator. When the pressure of the reaction system basically no longer changes, the reaction can be considered complete and the reaction is stopped.

[0124] In a preferred embodiment, the time of the radical reaction in step (A1) is 2 - 16 h, for example, it can be 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h, 14 h or 15 h, etc.

[0125] In the present invention, the metal salt in step (A2) is a water-soluble metal salt. Preferably, the metal salt includes metal sulfate and / or metal chloride, and more preferably metal sulfate.

[0126] In a preferred embodiment, the metal in the metal salt in step (A2) includes any one or a combination of at least two of Al, Ca, Cu, Zn, Fe, and Ti, and further preferably Al.

[0127] In a preferred embodiment, the metal salt in step (A2) includes aluminum sulfate.

[0128] It should be noted that the metal salt can be an anhydrous metal salt and / or a metal salt hydrate.

[0129] In a preferred embodiment, the mass percentage content of the metal salt in the aqueous solution of the metal salt in step (A2) is 20 - 40%, for example, it can be 22%, 25%, 28%, 30%, 32%, 35% or 38%, etc.

[0130] In a preferred embodiment, the molar ratio of the metal salt in step (A2) to the diethyl phosphite is 1:(5.8 - 6.2), for example, it can be 1:5.82, 1:5.85, 1:5.88, 1:5.9, 1:5.92, 1:5.95, 1:5.98, 1:6, 1:6.02, 1:6.05, 1:6.08, 1:6.1, 1:6.12, 1:6.15 or 1:6.18, etc. Further preferably, it is 1:6.

[0131] In a specific embodiment, the pH value of the reaction system in step (A2) is 3.5 - 3.8, and for example, it can be 3.52, 3.55, 3.58, 3.6, 3.62, 3.65, 3.68, 3.7, 3.72, 3.75 or 3.78, etc.

[0132] In a preferred specific embodiment, the alkali solution in step (A2) includes sodium hydroxide solution and / or potassium hydroxide solution.

[0133] The present invention has no special limitation on the mass concentration of the sodium hydroxide solution and the potassium hydroxide solution. Just add the sodium hydroxide solution and / or the potassium hydroxide solution to maintain the pH of the reaction system obtained in step (A2) at 3.5 - 3.8.

[0134] In a preferred specific embodiment, the temperature of the reaction in step (A2) is 20 - 80 °C, and for example, it can be 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, 65 °C, 70 °C or 75 °C, etc., and it is further preferably 40 - 60 °C.

[0135] In a preferred specific embodiment, the reaction time in step (A2) is 0.1 - 5 h, and for example, it can be 0.2 h, 0.5 h, 0.8 h, 1 h, 1.2 h, 1.5 h, 1.8 h, 2 h, 2.2 h, 2.5 h, 2.8 h, 3 h, 3.2 h, 3.5 h, 3.8 h, 4 h or 4.5 h, etc.

[0136] It should be noted that in step (A2), the metal salt aqueous solution and the alkali solution are simultaneously added to the diethylphosphinic acid salt aqueous solution for reaction, or the metal salt aqueous solution, the alkali solution and the diethylphosphinic acid salt aqueous solution are continuously added to the reaction device (such as a stirred reaction kettle, a static mixer, a dynamic mixer) at a constant flow rate for sufficient mixing reaction. Among them, when the metal salt aqueous solution and the alkali solution are simultaneously added to the diethylphosphinic acid salt aqueous solution for reaction, the reaction temperature is 20 - 80 °C, preferably 30 - 70 °C, and further preferably 40 - 60 °C. The dropping time of the metal salt aqueous solution and the alkali solution is 0.1 - 5 h (such as 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, etc.), preferably 0.5 - 3 h, and further preferably 1 h - 3 h. When the metal salt aqueous solution, the alkali solution and the diethylphosphinic acid salt aqueous solution are continuously added to the reaction vessel at a constant flow rate, the reaction temperature is 40 - 80 °C, preferably 50 - 60 °C, and the reaction space velocity is 0.1 - 2 / h (such as 0.2 / h, 0.5 / h, 0.8 / h, 1 / h, 1.2 / h, 1.5 / h, 1.8 / h, etc.), preferably 0.3 - 1 / h, and further preferably 0.5 - 0.8 / h.

[0137] In a preferred embodiment, in step (A3), based on the mass of the metal diethylphosphinate theoretically obtained being 100%, the mass of the flocculant is 0.01 - 0.5%, for example, it can be 0.02%, 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.18%, 0.2%, 0.22%, 0.25%, 0.28%, 0.3%, 0.32%, 0.35%, 0.38%, 0.4%, 0.42%, 0.45% or 0.48%, etc.

[0138] Among them, the "mass of the metal diethylphosphinate theoretically obtained" is calculated from the input amounts of the diethylphosphinate and the metal salt in step (A2).

[0139] In a preferred embodiment, the flocculant can be first mixed with water at 20 - 30 °C for 10 - 20 min to obtain a flocculant solution, and then the flocculant solution is mixed with the metal diethylphosphinate slurry and stirred. Among them, the mass ratio of the flocculant to water is 1:(10 - 1000), for example, it can be 1:50, 1:100, 1:200, 1:300, 1:400, 1:500, 1:600, 1:700, 1:800, 1:900 or 1:950, etc.

[0140] In a preferred embodiment, the temperature of the mixing in step (A3) is 40 - 60 °C, for example, it can be 42 °C, 44 °C, 46 °C, 48 °C, 50 °C, 52 °C, 54 °C, 56 °C or 58 °C, etc.

[0141] In a preferred embodiment, the number of times of washing in step (A3) is ≥4 times, for example, it can be 5 times, 6 times, 7 times, 8 times, 9 times, 10 times or 12 times, etc., and further preferably 5 - 10 times. Filtering and washing the diethylphosphinate flocculate multiple times can better remove impurities and acidic substances in the product and obtain the organophosphonate flame retardant with a low acid value.

[0142] Preferably, the washing reagent used for washing is water.

[0143] Preferably, the mass ratio of water to the solid matter in each washing is independently (1 - 10):1, for example, it can be 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, etc., and further preferably (1.5 - 6):1. The solid matter is the solid product obtained by filtration.

[0144] Preferably, the temperature of the drying in step (A3) is 105 - 250°C, for example, it can be 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 180°C, 200°C, 220°C or 240°C, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the specific point values included in the scope of the present invention are not exhaustively listed herein. Further preferably, it is 110 - 150°C.

[0145] In a preferred specific embodiment, the method I specifically comprises the following steps:

[0146] (A1) In an inert gas atmosphere, an aqueous solution of hypophosphite and an antioxidant are subjected to a free radical reaction with ethylene in the presence of an initiator to obtain an aqueous solution of diethylphosphinate;

[0147] Wherein, the mass percentage content of hypophosphite in the aqueous solution of hypophosphite is 10 - 60%, and the mass ratio of hypophosphite, antioxidant, and initiator is 100:(0.02 - 1.2):(0.1 - 5); the temperature of the free radical reaction is 70 - 120°C, and the reaction is terminated when the pressure of the system no longer changes;

[0148] (A2) The aqueous solution of diethylphosphinate, the aqueous solution of metal salt, and the alkali solution are mixed and reacted at a pH value of 3.5 - 3.8 and a temperature of 40 - 60°C to obtain a slurry of metal diethylphosphinate;

[0149] Wherein, the molar ratio of the metal salt to diethylphosphinate is 1:(5.9 - 6.1), and the mass percentage content of the metal salt in the aqueous solution of metal salt is 20 - 40%;

[0150] (A3) The slurry of metal diethylphosphinate and the flocculant solution are mixed at 40 - 60°C and stirred to obtain a flocculate of diethylphosphinate; the flocculate of diethylphosphinate is filtered, washed ≥4 times, and dried to obtain the organophosphonate flame retardant;

[0151] Wherein, based on the mass of the theoretically obtained metal diethylphosphinate being 100%, the mass of the flocculant is 0.01 - 0.5%.

[0152] In a preferred specific embodiment, the mass percentage content of hypophosphorous acid in the aqueous solution of hypophosphorous acid in step (B1) is 20 - 70%, for example, it can be 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60% or 65%, etc., and further preferably 45 - 55%.

[0153] In a preferred embodiment, the mass ratio of the hypophosphorous acid to the antioxidant in step (B1) is 100:(0.02-1.2), for example, it can be 100:0.04, 100:0.05, 100:0.06, 100:0.08, 100:0.1, 100:0.2, 100:0.3, 100:0.4, 100:0.5, 100:0.6, 100:0.7, 100:0.8, 100:0.9, 100:0.95, 100:1, 100:1.05, 100:1.1 or 100:1.15, and more preferably 100:(0.05-1).

[0154] In a preferred embodiment, the mass ratio of the hypophosphorous acid to the initiator in step (B1) is 100:(0.1-5), for example, it can be 100:0.2, 100:0.5, 100:1, 100:1.5, 100:2, 100:2.5, 100:3, 100:3.5, 100:4, 100:4.5 or 100:4.8, etc.

[0155] It should be noted that the initiator in step (B1) of the present invention can be added all at once, in batches, or continuously during the reaction; and a portion of the initiator in step (B1) can be added in advance, and the rest can be added continuously during the reaction.

[0156] In a preferred embodiment, the molar ratio of ethylene to hypophosphorous acid in step (B1) is (2-2.1):1, for example, it can be 2.01:1, 2.02:1, 2.04:1, 2.05:1, 2.06:1, 2.08:1 or 2.09:1, etc.

[0157] In a preferred embodiment, the free radical reaction in step (B1) is carried out in a protective atmosphere.

[0158] In a preferred embodiment, the protective atmosphere includes nitrogen atmosphere and / or argon atmosphere.

[0159] In a preferred embodiment, the temperature of the free radical reaction in step (B1) is 60-105°C, for example, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or 98°C, more preferably 70-100°C, further preferably 75-95°C.

[0160] The free radical reaction in step (B1) is carried out in the presence of an initiator. When the pressure of the reaction system substantially no longer changes, the reaction is considered complete and the reaction is stopped.

[0161] In a preferred embodiment, the time of the free radical reaction in step (B1) is 2 - 16 h, for example, it can be 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h, 14 h or 15 h, etc.

[0162] In a preferred embodiment, the metal hydroxide in step (B2) includes any one or a combination of at least two of aluminum hydroxide, calcium hydroxide, copper hydroxide, zinc hydroxide, iron hydroxide, and titanium hydroxide, and aluminum hydroxide is more preferred.

[0163] In a preferred embodiment, the iron hydroxide includes ferrous hydroxide and / or ferric hydroxide.

[0164] By using the above metal hydroxide, the cation in the diethyl phosphite obtained in step (B2) includes any one of Al, Ca, Cu, Zn, Fe or Ti, and Al is more preferred.

[0165] In a preferred embodiment, in step (B2), based on the molar amount of the diethyl phosphinic acid being 100%, the molar amount of the metal hydroxide is 30 - 50 mol%, for example, it can be 32 mol%, 33 mol%, 33.3 mol%, 34 mol%, 35 mol%, 36 mol%, 38 mol%, 40 mol%, 42 mol%, 45 mol% or 48 mol%, etc.

[0166] In a preferred embodiment, in step (B2), based on the molar amount of the diethyl phosphinic acid being 100%, the molar amount of sulfuric acid is 5 - 50 mol%, for example, it can be 8 mol%, 10 mol%, 12 mol%, 15 mol%, 18 mol%, 20 mol%, 22 mol%, 25 mol%, 28 mol%, 30 mol%, 32 mol%, 35 mol%, 38 mol%, 40 mol%, 42 mol%, 45 mol% or 48 mol%, etc., further preferably 8 - 30 mol%, and more preferably 10 - 15 mol%.

[0167] In a preferred embodiment, the temperature of the reaction in step (B2) is 70 - 150 °C, for example, it can be 75 °C, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C or 145 °C, etc., further preferably 80 - 120 °C, and more preferably 90 - 100 °C.

[0168] Preferably, the time of the reaction in step (B2) is 2 - 12 h, for example, it can be 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h or 11.5 h, etc.

[0169] In the present invention, the pH value of the diethyl phosphinate slurry in step (B2) is 3.8 - 4.2, and can be, for example, 3.82, 3.85, 3.88, 3.9, 3.92, 3.95, 3.98, 4, 4.02, 4.05, 4.08, 4.1, 4.12, 4.15 or 4.18, etc.

[0170] In a preferred specific embodiment, the alkali solution in step (B2) includes sodium hydroxide solution and / or potassium hydroxide solution.

[0171] The present invention has no special limitation on the mass concentration of the sodium hydroxide solution and the potassium hydroxide solution. Just add the sodium hydroxide solution and / or the potassium hydroxide solution to maintain the pH of the diethyl phosphinate slurry obtained in step (B2) at 3.8 - 4.2.

[0172] In a preferred specific embodiment, in step (B3), based on the mass of the theoretically obtained diethyl phosphinate being 100%, the mass of the flocculant is 0.01 - 0.5%, and can be, for example, 0.02%, 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.18%, 0.2%, 0.22%, 0.25%, 0.28%, 0.3%, 0.32%, 0.35%, 0.38%, 0.4%, 0.42%, 0.45% or 0.48%, etc.

[0173] Among them, the "mass of the theoretically obtained diethyl phosphinate" is calculated from the input amounts of diethyl phosphinic acid and metal hydroxide in step (B2).

[0174] In a preferred specific embodiment, the flocculant can be first mixed with water at 20 - 30°C for 10 - 20 min to obtain a flocculant solution, and then the flocculant solution is mixed with the diethyl phosphinate slurry and stirred. Among them, the mass ratio of the flocculant to water is 1:10 - 1000, and can be, for example, 1:50, 1:100, 1:200, 1:300, 1:400, 1:500, 1:600, 1:700, 1:800, 1:900 or 1:950, etc.

[0175] In a preferred specific embodiment, the temperature of the mixing in step (B3) is 40 - 60°C, and can be, for example, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C or 58°C, etc.

[0176] In a preferred specific embodiment, the number of times of washing in step (B3) is ≥4 times, and can be, for example, 5 times, 6 times, 7 times, 8 times, 9 times, 10 times or 12 times, etc., and more preferably 5 - 10 times.

[0177] Preferably, the washing reagent used for washing is water.

[0178] Preferably, the mass ratio of water to solid matter in each washing is independently (1 - 10):1, for example, it can be 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, etc., and more preferably (1.5 - 6):1. The solid matter is the solid product obtained by filtration.

[0179] Preferably, the drying temperature in step (B3) is 105 - 250 °C, for example, it can be 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 180 °C, 200 °C, 220 °C or 240 °C, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range. More preferably, it is 110 - 150 °C.

[0180] In a preferred specific embodiment, Method II specifically includes the following steps:

[0181] (B1) In an inert gas atmosphere, an aqueous hypophosphorous acid solution and an antioxidant react with ethylene under the action of an initiator to undergo a free radical reaction to obtain an aqueous solution of diethylphosphinic acid;

[0182] Among them, the mass concentration of the aqueous hypophosphorous acid solution is 20 - 70%, and the mass ratio of hypophosphorous acid, antioxidant, and initiator is 100:(0.02 - 1.2):(0.1 - 5); the temperature of the free radical reaction is 60 - 100 °C, and the reaction terminates when the pressure of the system no longer changes;

[0183] (B2) React the aqueous solution of diethylphosphinic acid, sulfuric acid, and metal hydroxide at 70 - 150 °C for 2 - 12 h, and then add an alkali solution to make the pH of the system 3.8 - 4.2 to obtain a diethylphosphinate slurry;

[0184] Among them, based on the molar amount of diethylphosphinic acid being 100%, the molar amount of the metal hydroxide is 30 - 50 mol%, and the molar amount of sulfuric acid is 5 - 50 mol%;

[0185] (B3) Mix the diethylphosphinate slurry and the flocculant solution at 40 - 60 °C, stir to obtain a diethylphosphinate floc; filter the diethylphosphinate floc, wash it ≥4 times, and dry it to obtain the organophosphonate flame retardant;

[0186] Among them, based on the mass of the theoretically obtained diethylphosphinate being 100%, the mass of the flocculant is 0.01 - 0.5%.

[0187] It should be noted that the preparation method of the organic phosphonate flame retardant described in the present invention is not limited to the aforementioned Method I and Method II, and those skilled in the art can also select other methods or routes to obtain the low acid value organic phosphonate flame retardant proposed by the present invention.

[0188] In the following specific embodiments, the test methods for the organic phosphonate flame retardants are as follows:

[0189] (1) Content test of diethyl phosphinate, ethyl butyl phosphinate, ethyl phosphonate, and monoethyl phosphinate

[0190] It is analyzed and tested by a liquid chromatograph (LC20A, Shimadzu, Japan). Among them, for diethyl phosphinate, a commercially available standard sample is used; for ethyl butyl phosphinate, its pure product (prepared according to Example 4 of CN103172668A) is used as the standard sample; for ethyl phosphonate, its pure product (prepared according to Example 2 of CN104371142A) is used as the standard sample; for monoethyl phosphinate, its pure product (prepared according to Example 1 of CN103172668A) is used as the standard sample. The sample to be tested is dissolved in a sulfuric acid aqueous solution (mass concentration 30%) at 5 times the sample mass, and then diluted 20 times with the mobile phase for analysis and testing. The mobile phase is a mixed solution of water and methanol with a mass ratio of 9:1, and 0.5% trifluoroacetic acid is added. The chromatographic column is ShimNex CS C18 5μm, 4.6×250mm, and the flow rate is 0.6 mL / min. The mass content of each component is calculated by the area normalization method.

[0191] (2) Content of alkali-insoluble substances

[0192] Take 5 g of the sample to be tested, stir it with 500 g of sodium hydroxide aqueous solution (mass concentration 3%) at 35°C for 30 min, filter it with a filter paper with a precision ≤ 2 μm, and wash it 3 times with 100 g of water. After drying the filter paper, weigh it. The mass increase relative to the mass before filtration (dry filter paper) is the mass of the insoluble substances. The ratio of the mass of the insoluble substances to the mass of the sample to be tested (5 g) is the mass content of the alkali-insoluble substances.

[0193] (3) Content of other phosphorus-containing compounds

[0194] The sample to be tested is mixed with a deuterated sodium hydroxide deuterated aqueous solution (mass concentration 10%) at a mass ratio of 1:30 to completely dissolve the sample, filter it, and the obtained clear liquid is measured by a nuclear magnetic resonance spectrometer (NMR, Bruker NMR spectrometer, AVANCENEO 400 MHz) to obtain a nuclear magnetic phosphorus spectrum. Integrate the nuclear magnetic phosphorus spectrum. The proportion of the integrated area of other peaks except for the known diethyl phosphinate, ethyl butyl phosphinate, ethyl phosphonate, and monoethyl phosphinate is regarded as the content of the other phosphorus-containing compounds.

[0195] (4) Water-soluble acid value

[0196] Take 1 g of the sample to be tested, add 5.00 ± 0.01 g (m 乙醇 ) of ethanol and wet it evenly, then add 50 ± 0.01 g (m 水 ) of normal-temperature water. Weigh the total weight m 0 including the bottle and stirrer. Boil it in a sealed container at 90 °C for 1 h, then cool it to 25 °C and keep it at a constant temperature for 30 min. Make up the ethanol aqueous solution (mass ratio of ethanol to water is 1:10) to the total weight m 0 . Filter it to obtain the mass of the clear filtrate as m 1 . Measure the acid value of the test by potentiometric titration method, and measure the blank acid value of (m 水 + m 乙醇 ) by potentiometric titration method. Among them, the concentration of the potassium hydroxide solution used in the titration is 0.05 mol / L. Water-soluble acid value = test acid value × (m 水 + m 乙醇 ) / m 1 - blank acid value.

[0197] (5) Organic acid value

[0198] Take 1 g of the sample to be tested, add 50.0 ± 0.01 g (m 二氯甲烷 ) of dichloromethane and wet it evenly. Weigh the total weight m 0 including the bottle and stirrer. Boil it in a sealed container at 90 °C for 1 h, then cool it to 25 °C and keep it at a constant temperature for 30 min. Make up dichloromethane to the total weight m 0 ; Filter it to obtain the mass of the clear filtrate as m 1 . Measure the acid value of the test by potentiometric titration method, and measure the blank acid value of the weight m 二氯甲烷 by potentiometric titration method. Among them, the concentration of the potassium hydroxide solution used in the titration is 0.05 mol / L. Organic acid value = test acid value × m 二氯甲烷 / m 1 - blank acid value.

[0199] (6) Mass content of sulfate radical

[0200] Refer to the method in the standard EN 14582:2007 - "Determination of halogen content", and use ion chromatography technology to measure by the external standard method.

[0201] In the following specific embodiments of the present invention, all materials without provided preparation methods are commercially available chemicals. The specific information of some materials is as follows:

[0202]

[0203]

[0204] The preparation method of the organophosphonate flame retardant described in the present invention will be described in detail below by taking multiple preparation examples as an example, but the preparation method of the organophosphonate flame retardant is not limited to these preparation examples.

[0205] Preparation Examples 1 - 5, Comparative Preparation Examples 1 - 6

[0206] The preparation method of the organophosphonate flame retardant includes the following steps:

[0207] (1) Put 31.8 kg of solid sodium hypophosphite monohydrate, 40 kg of water, 200 g of sodium persulfate, antioxidant 1010 with a mass of m 1 and antioxidant 168 with a mass of m 2 into an autoclave, displace with nitrogen 3 times, keep the pressure of ethylene constant at 1.5 MPa through a pressure reducer, heat to 100 °C, keep warm for 4 h, continuously supplement 2500 g of an aqueous sodium persulfate solution with a mass content of 15% during the 4 - h heat preservation process, then keep warm at 100 °C for 1 h, cool and vent to obtain an aqueous solution of sodium diethylphosphinate;

[0208] (2) Dilute the aqueous solution of sodium diethylphosphinate obtained in step (1) to a mass content of 20% of sodium diethylphosphinate (containing 6 mol of sodium diethylphosphinate), heat to temperature T 1 , continuously dropwise add an aqueous solution of aluminum sulfate (1 mol of aluminum sulfate, with a mass content of 25%) within 1 h, and control the pH value with a potassium hydroxide solution (with a mass content of 5%) to obtain an aluminum diethylphosphinate slurry;

[0209] (3) Add an aqueous solution of a flocculant prepared from anionic polyacrylamide with a mass of m 3 and 50 g of water to the aluminum diethylphosphinate slurry obtained in step (2) at 50 °C, stir until in a flocculent state, filter, wash the filter cake with 3 times the mass of water for n times, and dry at 120 °C to constant weight to obtain the organophosphonate flame retardant.

[0210] The specific process parameters of the preparation method and the relevant data of the prepared organophosphonate flame retardant are shown in Table 1.

[0211] Table 1

[0212]

[0213]

[0214] Preparation Examples 6 - 8, Comparative Preparation Examples 7 - 10

[0215] The preparation method of the organophosphonate flame retardant is as follows:

[0216] (1) Put 39.6 kg of hypophosphorous acid aqueous solution with a mass content of 50%, 500 g of sodium persulfate, and an antioxidant with a mass of m 4 into an autoclave, displace with nitrogen 3 times, keep the pressure of ethylene constant at 1.5 MPa through a pressure reducer, heat to 85 °C, keep warm for 5.5 h, continuously supplement 3500 g of sodium persulfate aqueous solution with a mass content of 10% during the heat preservation process, then keep warm at 85 °C for 1.5 h, cool and vent to obtain diethylphosphinic acid aqueous solution;

[0217] (2) Mix the diethylphosphinic acid aqueous solution obtained in step (1) (diethylphosphinic acid is 6 mol), sulfuric acid aqueous solution (the mass content of sulfuric acid is 30%, and the molar amount is 0.6 mol), and 2 mol of aluminum hydroxide, heat to 90 °C, stir and react for 8 h, and adjust the pH value with sodium hydroxide solution (mass content is 10%) to obtain diethylphosphinate slurry;

[0218] (3) Add an aqueous solution of flocculant prepared from anionic polyacrylamide with a mass of m 5 and 50 g of water to the diethylphosphinate slurry obtained in step (2) at 50 °C, stir until aluminum diethylphosphinate flocs are formed, filter, wash the filter cake 5 times with 3 times the mass of water, and dry to constant weight at 110 °C to obtain an organophosphonate flame retardant.

[0219] The specific process parameters of the preparation method and the relevant data of the obtained organophosphonate flame retardant are shown in Table 2; "--" indicates that the material is not added.

[0220] Table 2

[0221]

[0222] Next, the polyamide composite material of the present invention will be described in detail by taking examples as an example, but the polyamide composite material is not limited to these examples.

[0223] In the following examples, the materials for which the preparation methods are not provided are all commercially available chemicals, and the specific information is as follows:

[0224]

[0225]

[0226] Examples 1 - 12, Comparative Examples 1 - 10

[0227] A polyamide composite material, the types and dosages of each component are shown in Table 3 and Table 4, and the dosage unit of each component is "parts by mass".

[0228] The preparation method of the polyamide composite material comprises: mixing polyamide resin, glass fiber, organic phosphonate flame retardant, MPP, antioxidant and lubricant according to the formula amount to obtain a premix; adding the premix to a twin-screw extruder, the screw speed of the twin-screw extruder being 380 rpm, the temperatures of zones 1-12 of the PA66 system being 90°C, 180°C, 260°C, 250°C, 230°C, 230°C, 220°C, 220°C, 220°C, 220°C, 260°C, 260°C respectively, and the temperatures of zones 1-12 of the PA10T system being 120°C, 260°C, 310°C, 300°C, 260°C, 260°C, 260°C, 260°C, 260°C, 260°C, 290°C, 310°C respectively, and performing melt mixing and extrusion granulation to obtain the polyamide composite material.

[0229] The following performance tests are carried out on the polyamide composite material:

[0230] (1) Boiling water phosphorus content test: Take 50 g of polyamide composite material particles, add them to 500 mL of hot water at 90°C, boil for 1 h, cool to room temperature, filter, and measure the phosphorus content of the filtrate by the ammonium molybdate spectrophotometric method of GB / T 11893-1989;

[0231] (2) Mold fouling test method: Using an injection molding machine, continuously inject 150 molds of polyamide composite material particles at injection temperatures of 290°C, 285°C, 280°C, and 260°C, take the mold fouling sample in the finally collected mold, and weigh it using an analytical balance;

[0232] The test data are shown in Tables 3 and 4.

[0233] Table 3

[0234]

[0235] Table 4

[0236]

[0237]

[0238] According to the data in Table 3, it can be seen that the polyamide composition provided by the present invention uses an organic phosphonate flame retardant with a low acid value, which can significantly reduce the mold fouling generated during injection molding, making the mold fouling ≤ 7.2 mg, and the boiling water phosphorus content of the polyamide composition ≤ 507 ppm, reducing the content of boiling water precipitates, improving the wet heat stability of the polyamide composition, and extending its service life under wet heat conditions.

[0239] According to the test data in Table 4, since the acid value of the organophosphonate flame retardant in Comparative Examples 1-10 is relatively high, there are more injection mold deposits in the polyamide composition, the phosphorus content after boiling water treatment increases, and the stability under humid and hot conditions is poor.

[0240] The applicant declares that the polyamide composite material and its application of the present invention are illustrated by the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent substitution of each raw material of the product of the present invention, the addition of auxiliary components, and the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A polyamide composite material, characterized in that: The polyamide composite material comprises the following components in parts by mass: Polyamide resin 35-82 parts Reinforcement material 5-45 parts 5-25 parts of organic phosphonate flame retardant; The water-soluble acid value of the organic phosphonate flame retardant is 0.1-0.3 mg KOH / g.

2. The polyamide composite material according to claim 1, characterized in that: The polyamide resin includes any one of polyamide 6, polyamide 11, polyamide 12, polyamide 66, polyamide 46, polyamide 610, polyamide 611, polyamide 612, polyamide 1010, polyamide 6T, polyamide 9T, and polyamide 10T, or a combination of at least two thereof; Preferably, the reinforcing material includes any one of glass fiber, carbon fiber, polyaramid fiber, asbestos fiber, wollastonite fiber, ceramic fiber, potassium titanate whisker, basic magnesium sulfate whisker, silicon carbide whisker, aluminum borate whisker, or a combination of at least two thereof.

3. The polyamide composite material according to claim 1, characterized in that: The organic phosphonate flame retardant comprises the following components in parts by mass:

4. The polyamide composite material according to claim 3, characterized in that: The cations in the diethylphosphinate, ethylbutylphosphinate, ethylphosphonate and monoethylphosphinate each independently include Al 3+ , Ca 2+ , Cu 2+ 、Zn 2+ , Fe 2+ , Fe 3+ 、Ti 4+ Any one or a combination of at least two of the following, preferably Al 3+ ; Preferably, the organic phosphonate flame retardant further comprises alkali-insoluble matter, and the alkali-insoluble matter comprises any one or a combination of at least two of hydroxide, oxide, phosphate, pyrophosphate, polyphosphate and phosphite; Preferably, the mass fraction of alkali-insoluble matter in the organic phosphonate flame retardant is ≤3 parts; Preferably, the organic phosphonate flame retardant further comprises other phosphorus-containing compounds, and the mass fraction of other phosphorus-containing compounds in the organic phosphonate flame retardant is ≤1 part.

5. The polyamide composite material according to claim 1, characterized in that: The organic acid value of the organic phosphonate flame retardant is ≤0.05 mg KOH / g, preferably 0.001-0.04 mg KOH / g; Preferably, the mass content of sulfate in the organic phosphonate flame retardant is 100-500 ppm, more preferably 110-430 ppm.

6. The polyamide composite material according to claim 1, characterized in that: The polyamide composite material further comprises 1-15 parts by weight of melamine flame retardant; Preferably, the melamine flame retardant includes any one of melamine polyphosphate salt, melamine pyrophosphate salt, piperazine pyrophosphate, polyphosphate melam salt, pyrophosphate melam salt, phosphate melam salt, diethylphosphinate melam salt, ethylphosphinate melam salt, phosphite melam salt, alkylphosphonate melam salt or a combination of at least two thereof; Preferably, the mass ratio of the organic phosphonate flame retardant to the melamine flame retardant is 1:(0.1-3); Preferably, the polyamide composite material further comprises any one or a combination of at least two of a synergistic flame retardant, an antioxidant, and a lubricant; Preferably, the synergistic flame retardant includes any one of zinc borate, zinc stannate, zinc sulfide, and boehmite, or a combination of at least two thereof; Preferably, the mass fraction of the synergistic flame retardant in the polyamide composite material is ≤5 parts; Preferably, the polyamide composite material further comprises 0.01-1 parts by weight of an antioxidant; Preferably, the polyamide composite material further comprises 0.01-1 parts by mass of a lubricant.

7. The polyamide composite material according to claim 1, characterized in that: The water-boiled phosphorus content of the polyamide composite material is ≤510ppm, preferably 370-507ppm; Preferably, the injection mold deposit of the polyamide composite material is ≤7.5 mg, more preferably 4-7.2 mg.

8. A method for preparing a polyamide composite material according to any one of claims 1 to 7, characterized in that: The preparation method comprises: melt-blending a polyamide resin, a reinforcing material and an organic phosphonate flame retardant and then extruding the mixture to obtain the polyamide composite material.

9. The preparation method according to claim 8, characterized in that: The preparation method comprises the following steps: Mixing a polyamide resin and an organic phosphonate flame retardant to obtain a premix; The premix and the reinforcing material are melt-blended and then extruded to obtain the polyamide composite material; Preferably, the mixed material further comprises any one or a combination of at least two of melamine flame retardants, synergistic flame retardants, antioxidants, and lubricants; Preferably, the melt blending is carried out in a screw extruder; Preferably, the temperature of the screw extruder is 180-330°C; Preferably, the extrusion further includes granulation and drying steps.

10. Use of the polyamide composite material according to any one of claims 1 to 7 in electronic appliances, electrical product parts, energy storage devices, connectors or automotive parts.

Images