Flame-retardant polyamide composition as well as preparation method and application thereof

Abstract

The invention discloses a flame-retardant polyamide composition, which is prepared from the following components in parts by weight: 10 to 40 parts of semi-aromatic polyamide, 10 to 40 parts of PBT (Polybutylene Terephthalate), 10 to 40 parts of PPO (Polyphenylene Oxide), 4.8 to 10 parts of red phosphorus and 5 to 10 parts of charring agent, the pH (Potential of Hydrogen) value of the alkaline charring agent is 8 to 10. Through the semi-aromatic polyamide with a benzene ring structure, PBT and PPO in specific content, the charring performance is enhanced, the addition amount of the red phosphorus can be effectively reduced, the GWIT performance is improved, phosphorus precipitation can be inhibited, the addition amount of the red phosphorus can be reduced by adding the alkaline charring agent, meanwhile, free phosphorus in a resin matrix can be adsorbed by the alkaline charring agent, and the flame retardance of the resin matrix is improved. The metal corrosion of the red phosphorus flame-retardant polyamide composition is further reduced.

Description

Technical Field

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

[0002] Polyamide resins possess excellent comprehensive properties, including mechanical properties, barrier properties, heat resistance, abrasion resistance, and chemical corrosion resistance. Their composite materials are widely used in machinery manufacturing, industrial connectors, power tools, electronics, and transportation. Halogen-free red phosphorus flame-retardant nylon is widely used in the photovoltaic and electronics industries due to its excellent comprehensive mechanical properties and flame-retardant properties. Unlike halogenated bromine-based flame-retardant nylons, the low ignition point of red phosphorus in halogen-free red phosphorus flame-retardant nylon systems results in lower GWIT performance, failing to meet the IEC 60695-2 standard (i.e., no ignition at 750°C measured with a glow wire) required for unattended household appliances.

[0003] Currently, the modification of the GWIT performance of red phosphorus flame-retardant polyamide systems mainly involves modifying the flame retardant. For example, Chinese patent application CN111138850A discloses a polyamide composite material comprising 20-80 parts of polyamide resin, 1-30 parts of red phosphorus flame retardant, and 0.01-10 parts of methyltriallyl isocyanurate. The addition of methyltriallyl isocyanurate for radiation crosslinking results in high GWIT performance. Chinese patent application CN 119101352A discloses a halogen-free flame-retardant nylon material comprising 6-61 parts of semi-aromatic polyamide resin, PA6 or PA66, 8-15 parts of red phosphorus flame retardant, and 1-5 parts of melamine derivative. This halogen-free flame-retardant nylon material exhibits GWIT performance at ≥775℃. CN 111171556 A discloses a polyamide composition comprising 100 parts of polyamide resin, 10-35 parts of red phosphorus flame retardant masterbatch, and 0.15-8 parts of aluminum phosphite. This patent utilizes the fact that aluminum phosphite, under high-temperature conditions, reacts with the decomposition products of red phosphorus to form an aluminum phosphate ceramic layer that covers the surface of the burning component, thereby reducing the contact between oxygen and the component, thus improving the flame retardant efficiency of the material and increasing the glow wire ignition point of the material. Chinese patent application CN 114395248 A discloses a red phosphorus flame retardant polyamide composite material comprising 20-70 parts of aliphatic polyamide, 5-20 parts of aromatic polyamide, 10-50 parts of glass fiber, 8-20 parts of red phosphorus flame retardant, and 1-5 parts of synergists (zinc borate, magnesium hydroxide, aluminum hydroxide, montmorillonite). This composite material, by introducing aromatic polyamide with a special structure, works synergistically with the red phosphorus flame retardant and synergists, achieving a GWIT value of 775-800℃ and also improving fiber floating defects.

[0004] However, none of the aforementioned patents describe how to improve the corrosion caused by the precipitation of red phosphorus. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical defects and provide a flame-retardant polyamide composition with high GWIT and low phosphorus release, as well as its preparation method and application.

[0006] This invention is achieved through the following scheme: A flame-retardant polyamide composition, comprising the following components in parts by weight: 10-40 parts of semi-aromatic polyamide; PBT 10-40 copies; 10-40 portions of PPO; 4.8-10 parts red phosphorus; 5-10 parts of alkaline charring agent; The pH value of the alkaline char-forming agent is 8-10.

[0007] In the flame-retardant polyamide composition of the present invention, the content of semi-aromatic polyamide can be any value selected from 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, and 40 parts, or a range between the two; the content of PBT can be any value selected from 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, and 40 parts, or a range between the two; the content of PPO can be 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, and 40 parts. The content of red phosphorus can be any value or a range between the two; the content of red phosphorus can be any value or a range between the two, such as 4.8 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts, 9 parts, 9.5 parts, or 10 parts; the content of alkaline charring agent can be any value or a range between the two, such as 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts, 9 parts, 9.5 parts, or 10 parts.

[0008] Optionally, the semi-aromatic polyamide is selected from at least one of PA4T, PA6T, PA6I, PA9T, PA10T, PA12T, and PAMXD6.

[0009] Preferably, the semi-aromatic polyamide is selected from PAMXD6.

[0010] Preferably, the composition is 18-32 parts of semi-aromatic polyamide, 15-35 parts of PBT, and 20-30 parts of PPO.

[0011] This invention does not specifically limit the relative viscosity; the relative viscosity range of the semi-aromatic polyamide can be 1.9-3.0. The test method follows the ISO 307 sulfuric acid method. The polyamide resin is dissolved in concentrated sulfuric acid (96% by mass) to prepare a concentrated sulfuric acid solution with a concentration of 0.01 g / mL, which is used as the test solution. The time it takes for this test solution to flow through an Ubbelohde viscometer at 25°C is recorded as t1. The time it takes for the concentrated sulfuric acid (96% by mass) to flow through the Ubbelohde viscometer at 25°C is recorded as t2. Then, t1 / t2 is the relative viscosity of the polyamide resin.

[0012] The intrinsic viscosity range of the PBT is 0.7-1.2 dL / g, and the test conditions are 25℃, using ISO 1628-52015.

[0013] The PPO is polymerized from 2,6-dimethylphenol or its derivatives, and its intrinsic viscosity range can be 30-60 μL. 3 / g, the intrinsic viscosity of PPO was determined using an Ubbelohde viscometer in chloroform at 25°C.

[0014] The pH range of alkaline charring agents can be any value or a range between 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, and 10.0.

[0015] In the flame-retardant polyamide composition of the present invention, the alkaline charring agent accounts for a total mass percentage ranging from 3.7 to 22.3 wt%.

[0016] Preferably, the pH value of the alkaline charring agent is 8.5-9.5. When the pH value of the alkaline charring agent is too high, it will cause degradation of the resin matrix, which may increase phosphorus precipitation or reduce GWIT.

[0017] The method for testing the pH value of the alkaline charring agent is as follows: Dissolve 0.1g of alkaline charring agent in 100mL of deionized water, boil at 80℃ for 4 hours, then filter with a 220-micron pore size filter membrane, and test the pH value of the filtrate after cooling.

[0018] The alkaline char-forming agent is selected from, but is not limited to, at least one of alkaline wollastonite, alkaline kaolin, alkaline talc, and alkaline calcium carbonate.

[0019] Preferably, the alkaline char-forming agent is selected from alkaline wollastonite.

[0020] The average particle size range of alkaline charring agents can be 800-3000 mesh.

[0021] The conventional particle size of commercially available alkaline charring agents has no significant impact on GWIT and phosphorus precipitation inhibition performance. The average particle size range can be 1-25 μm. The test method is to weigh 0.5 g of alkaline charring agent, add it to 20 mL of anhydrous ethanol, add 3-4 drops of dispersant polyvinylpyrrolidone, sonicate at 600 W for 30 min, and then take 2 mL and drop it into a quartz cuvette. Place it in a laser particle size analyzer to measure Dv50 to obtain the average particle size.

[0022] Red phosphorus is derived from red phosphorus flame retardants, and in existing technologies, the red phosphorus content in red phosphorus flame retardants is 40-80 wt%. The weight percentage of red phosphorus in the flame-retardant polyamide composition of this invention represents the actual red phosphorus content in the red phosphorus flame retardant.

[0023] In the flame-retardant polyamide composition of the present invention, the red phosphorus accounts for 3.5-22.2 wt% of the total mass.

[0024] To improve the strength of the flame-retardant polyamide composition, 0-40 parts of glass fiber can be added. Those skilled in the art may choose to add 0-2 parts of an additive as needed, wherein the additive is selected from lubricants. The lubricant is selected from at least one of hydrocarbon lubricants, ester lubricants, alcohol lubricants, fatty acid lubricants, fatty amide lubricants, and metal soap lubricants.

[0025] The method for preparing the flame-retardant polyamide composition of the present invention includes the following steps: mixing each component evenly according to the formula, extruding and granulating to obtain the flame-retardant polyamide composition.

[0026] The temperature of the screw barrel is set to 160-330℃, and the screw speed range is 300-400 rpm.

[0027] The flame-retardant polyamide composition of the present invention is used in the preparation of electrical components.

[0028] The present invention has the following beneficial effects: This invention improves the compatibility of semi-aromatic polyamide, PBT, and PPO with specific amounts of benzene ring structures, along with the addition of a compatibilizer. Firstly, the benzene ring structure exhibits strong charring properties, achieving V-0 flame retardancy while reducing the need for red phosphorus flame retardants and lowering the risk of phosphorus release. Secondly, the benzene ring structure acts as a barrier, inhibiting phosphorus release. Furthermore, the addition of an alkaline charring agent neutralizes phosphine generated during production, further reducing phosphorus release and the metal corrosivity of the red phosphorus flame-retardant polyamide composition. Detailed Implementation

[0029] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0030] The raw materials used in this invention are sourced from the following sources: PAMXD6: Model PA MXD6 M30L, manufactured by Beijing Anaiji Energy Engineering Technology Co., Ltd., with a relative viscosity of 2.2.

[0031] PA6T: Model KFHP41, manufactured by Zhuhai Wantong Special Engineering Plastics Co., Ltd., with a relative viscosity of 2.2.

[0032] PA9T: Model N1000A-M41, manufactured by Kuraray Trading (Shanghai) Co., Ltd., with a relative viscosity of 2.2.

[0033] PA10T: Model KFHP611, manufactured by Zhuhai Wantong Special Engineering Plastics Co., Ltd., with a relative viscosity of 2.1.

[0034] PA12T: Model PA12T 20 N 00, manufacturer: Henan Junheng Industrial Group Biotechnology Co., Ltd., relative viscosity: 2.1.

[0035] PA6: Model number J2000, manufactured by Hangzhou Juhua Shun New Material Co., Ltd., with a relative viscosity of 2.0.

[0036] PA612: Model A120, manufactured by Shanghai Yinggu Chemical Co., Ltd., with a relative viscosity of 2.2.

[0037] PPO-1: The monomer is 2,6-dimethylphenol, model number LXR035, manufactured by Nantong Xingchen Synthetic Materials Co., Ltd., with an intrinsic viscosity of 35-38 cm⁻¹. 3 / g.

[0038] PPO-2: The monomer is a 2,6-dimethylphenol derivative, model number LXR040, manufactured by Nantong Xingchen Synthetic Materials Co., Ltd., with an intrinsic viscosity of 40-42 cm⁻¹. 3 / g.

[0039] PBT-1: Model number PBT GX112, manufactured by Yizheng Branch of China Petrochemical Corporation Asset Management Co., Ltd., intrinsic viscosity 0.8 dL / g; PBT-2: Model number PBT GL236, manufactured by Yizheng Branch of China Petrochemical Corporation Asset Management Co., Ltd., intrinsic viscosity 1.2 dL / g; Red phosphorus flame retardant: Model FR9950T, manufacturer: Tongcheng Shinde New Materials Co., Ltd., red phosphorus content percentage: 50%; Alkaline wollastonite A: pH 8.2, 2500 mesh, obtained by grinding and crushing AT-0026 (1250 mesh) and sieving (manufacturer: Jiangxi Aote Technology Co., Ltd.); Alkaline wollastonite B: pH 8.8, 2500 mesh, obtained by grinding and crushing 400 mesh XYNFW-A and then sieving (manufacturer: Xinyu Nanfang Wollastonite Co., Ltd.). Alkaline wollastonite C: pH 9.3, 2500 mesh, obtained by grinding and crushing 400 mesh YD-45 and sieving (manufacturer: Tianjin Yandong Mineral Products Co., Ltd.); Alkaline wollastonite D: pH 9.9, 2500 mesh, obtained by grinding and crushing NYAD 400 with a particle size of 8μm and then sieving (manufacturer: Shanghai Huazhongrong Industry & Trade Co., Ltd.). Alkaline kaolin: pH 8.2, 2500 mesh, model CMP-1, manufacturer: China Kaolin Co., Ltd. Alkaline talc powder: pH 9.1, 2500 mesh, obtained by grinding and crushing HX-658 with an average particle size of 12μm and then sieving (manufacturer: Haicheng Xinguangyuan Powder Materials Co., Ltd.). Alkaline calcium carbonate: pH 8.8, 2500 mesh, obtained by grinding and crushing XL-05D with an average particle size of 8μm and then sieving (manufacturer: Guangdong Xianglong Technology Co., Ltd.). Ordinary wollastonite: pH 7.3, 2500 mesh, obtained by grinding and crushing KT-20028 with an average particle size of 325 mesh and then sieving (manufacturer: Jiangxi Kete Fine Powder Co., Ltd.). Ordinary kaolin: pH 6.0, 2500 mesh, obtained by grinding and crushing PVC Y-1 with an average particle size of 8μm and then sieving (manufacturer: Gaozhou Zhaoxiang New Materials Co., Ltd.). Fiberglass: Model ECS10-03-568H, manufactured by China Jushi Co., Ltd. Preparation method of flame-retardant polyamide composition in the examples and comparative examples: The components are mixed evenly according to the formula, and extruded and granulated (glass fiber side feeding) to obtain flame-retardant polyamide composition; the temperature of the barrel is set to 160-330℃ and the screw speed is 300 rpm.

[0040] Test methods: (1) GWIT: Tested according to IEC 603695-2-13 standard, the test sample size is 60*60*1mm.

[0041] (2) Phosphorus precipitation test: Place a 125mm*13mm*0.8mm sample strip in 50mL of deionized water, boil it at 50℃ for 28 days, and then test the phosphorus concentration (mass content) in the deionized water according to IEC 62321-5:2013 standard. The present invention requires that the phosphorus concentration in the water be <100ppm.

[0042] (3) Flame retardancy rating test: The test is conducted in accordance with the UL 94 standard, and the test strip size is 125mm*13mm*0.8mm.

[0043] Table 1: Weight parts of each component and test results of the flame-retardant polyamide compositions in Examples 1-5 Example 1 Example 2 Example 3 Example 4 Example 5 PAMXD6 10 25 40 18 32 PBT-1 20 10 40 35 15 PPO-1 40 10 30 20 30 Red phosphor 5 9 7.5 9 9 Alkaline kaolin 7 5 10 5 5 Glass fiber 20 Flame retardant rating V-0 V-0 V-0 V-0 V-0 Phosphorus element concentration, ppm 58.1 70.3 65.6 41.6 37.4 GWIT, °C 800 800 800 800 800 Note: The red phosphorus content in the table above and below refers to the effective content of red phosphorus in the red phosphorus flame retardant.

[0044] As can be seen from Examples 2 / 4 / 5, when the content of semi-aromatic polyamide / PBT / PPO is preferred, the precipitation of phosphorus is significantly less.

[0045] Table 2: Weight parts of each component and test results of the flame-retardant polyamide compositions in Examples 6-9 Example 6 Example 7 Example 8 Example 9 PAMXD6 25 PA6T 25 PA10T 25 PA12T 25 PBT-1 10 10 10 PBT-2 10 PPO-1 10 10 10 PPO-2 10 Red phosphor 9 9 9 9 Alkaline kaolin 5 5 5 5 Flame retardant rating V-0 V-0 V-0 V-0 Phosphorus element concentration, ppm 80.3 87.6 91.7 75.6 GWIT, °C 800 800 800 800 As can be seen from Examples 2 / 6 / 7 / 8, less phosphorus is released when the semi-aromatic polyamide is selected from PAMXD6.

[0046] Table 3: Weight parts of each component and test results of the flame-retardant polyamide compositions in Examples 10-15 Example 10 Example 11 Example 12 Example 13 Example 14 Example 15 PAMXD6 25 25 25 25 25 25 PBT-1 10 10 10 10 10 10 PPO-1 10 10 10 10 10 10 Red phosphor 9 9 9 9 9 9 Alkaline wollastonite A 5 Alkaline wollastonite B 5 Alkaline wollastonite C 5 Alkaline wollastonite D 5 Alkaline talc powder 5 Alkaline calcium carbonate 5 Flame retardant rating V-0 V-0 V-0 V-0 V-0 V-0 Phosphorus element concentration, ppm 68.9 52.5 58.2 65.4 80.7 82.5 GWIT, °C 800 800 800 800 800 800 As can be seen from Examples 2 / 10-15, less phosphorus is released when the alkaline char-forming agent is selected from alkaline wollastonite.

[0047] As can be seen from Examples 10-13, less phosphorus is released at the pH value of the preferred alkaline charring agent.

[0048] Table 4: Weight parts of each component and test results of flame-retardant polyamide compositions in Comparative Examples 1-4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 PAMXD6 25 25 PA6 25 PA612 25 PBT-1 10 10 10 10 PPO-1 10 10 10 10 Red phosphor 9 9 9 9 Alkaline kaolin 5 5 Common wollastonite 5 Common kaolin 5 Flame retardant rating V-0 V-0 V-0 V-0 Phosphorus element concentration, ppm 105.7 114.2 150.5 174.3 GWIT, °C 775 750 750 750 As shown in Comparative Example 1 / 2, using aliphatic polyamide reduces the benzene ring content in the resin matrix, decreases GWIT performance, and also results in significantly more precipitation.

[0049] As can be seen from Comparative Example 3 / 4, when using wollastonite and kaolin with ordinary pH values, not only is the GWIT low, but excessive precipitation also occurs.

[0050] Table 5: Weight parts of each component and test results of flame-retardant polyamide compositions of Comparative Examples 5-10 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 PAMXD6 25 25 35 35 35 5 PBT-1 10 10 10 0 5 20 PPO-1 10 10 0 10 5 20 Red phosphor 9 9 9 9 9 9 Alkaline kaolin 0 20 5 5 5 5 Flame retardant rating V-0 V-0 V-0 V-0 V-0 V-0 Phosphorus element concentration, ppm 195.8 88.5 75.4 86.4 92.7 125.8 GWIT, °C Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 PAMXD6 PBT-1 PPO-1 Red phosphor Alkaline kaolin Flame retardant rating Phosphorus element concentration, ppm GWIT, °C 750 775 750 750 750 775 As shown in Comparative Example 5, not only is the GWIT low when there is no alkaline char-forming agent, but also excessive precipitation occurs.

[0051] As shown in Comparative Example 6, when the content of alkaline char-forming agent is too high, GWIT decreases.

[0052] As can be seen from Comparative Examples 7-8, GWIT only reaches 750℃ when it does not contain PPO or PBT.

[0053] As shown in Comparative Example 9, when the PPO and PBT contents are too low, GWIT only reaches 750℃.

[0054] As shown in Comparative Example 10, when the content of semi-aromatic polyamide is too low, more phosphorus is released, and GWIT cannot reach 800℃.

Claims

1. A flame-retardant polyamide composition, characterized in that, By weight, it includes the following components: 10-40 parts of semi-aromatic polyamide; PBT 10-40 copies; 10-40 portions of PPO; 4.8-10 parts red phosphorus; 5-10 parts of alkaline charring agent; The pH value of the alkaline char-forming agent is 8-10.

2. The flame-retardant polyamide composition according to claim 1, characterized in that, The semi-aromatic polyamide is selected from at least one of PA4T, PA6T, PA6I, PA9T, PA10T, PA12T, and PAMXD6; preferably, the semi-aromatic polyamide is selected from PAMXD6.

3. The flame-retardant polyamide composition according to claim 2, characterized in that, 18-32 parts of semi-aromatic polyamide, 15-35 parts of PBT, and 20-30 parts of PPO.

4. The flame-retardant polyamide composition according to claim 1, characterized in that, The intrinsic viscosity range of the PBT is 0.7-1.2 dL / g.

5. The flame-retardant polyamide composition according to claim 1, characterized in that, The PPO is polymerized from 2,6-dimethylphenol or its derivatives, and its intrinsic viscosity ranges from 30 to 60 cm⁻¹. 3 / g.

6. The flame-retardant polyamide composition according to claim 1, characterized in that, The alkaline char-forming agent is selected from at least one of alkaline wollastonite, alkaline kaolin, alkaline talc, and alkaline calcium carbonate.

7. The flame-retardant polyamide composition according to claim 6, characterized in that, The alkaline char-forming agent is selected from alkaline wollastonite; the pH value of the alkaline char-forming agent is 8.5-9.

5.

8. The flame-retardant polyamide composition according to claim 1, characterized in that, It also includes 0-40 parts by weight of glass fiber; and / or 0-2 parts by weight of additives selected from lubricants.

9. A method for preparing the flame-retardant polyamide composition according to any one of claims 1-8, characterized in that, Includes the following steps: According to the formula, the components are mixed evenly, extruded and granulated to obtain a flame-retardant polyamide composition.

10. The application of the flame-retardant polyamide composition according to any one of claims 1-8, characterized in that, Used to manufacture electrical components.