Flame-retardant polyamide composite material as well as preparation method and application thereof

Abstract

The invention discloses a flame-retardant polyamide composite material which comprises the following components in parts by weight: 45-52 parts of polyamide resin; 0.5 to 2 parts of poly (pentabromobenzyl acrylate); 17-30 parts of a flame retardant; 10 to 50 parts of glass fiber; the polyamide resin is compounded by crystalline polyamide and amorphous polyamide, and the weight ratio of the crystalline polyamide to the amorphous polyamide is (1.09-1.92): 1; the flame retardant is compounded by a macromolecular brominated flame retardant and antimony white, and the weight ratio of the macromolecular brominated flame retardant to the antimony white is (3-9): 1. The specific crystalline polyamide and amorphous polyamide are compounded, and the poly (pentabromobenzyl acrylate) is used as the surface modifier, so that on one hand, the crystallization rate of the brominated flame-retardant reinforced PA material in injection molding can be greatly reduced, the melt flowability is improved, and on the other hand, floating fibers can be improved; meanwhile, good thermal stability of the material can be kept, and the appearance of the material can be greatly improved.

Description

Technical Field

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

[0002] Flame-retardant nylon materials possess excellent strength and toughness, making them widely used in the electronics and electrical industries. Brominated flame-retardant reinforced PA, on the other hand, exhibits high thermal stability, high strength, and a high glow wire ignition temperature, leading to its increasingly widespread application in relays, home appliances, and other fields. With the upgrading of the electrical industry, the structure of components is becoming increasingly complex, and there is a greater pursuit of aesthetic appearance. However, flame-retardant modified nylon materials often incorporate a significant amount of glass fiber, reducing melt flowability. If the crystallization rate is rapid at this point, it can lead to defects in certain areas of the injection-molded, complex components, along with a large amount of loose fiber. Existing technologies can improve this through injection molding processes, but these generally require stringent conditions, such as mold temperatures exceeding 120°C and injection temperatures above 290°C. This can cause material degradation and negatively impact energy efficiency. Therefore, this severely limits the use of halogenated flame-retardant polyamide materials in more complex and aesthetically pleasing components. Summary of the Invention

[0003] The purpose of this invention is to provide a flame-retardant polyamide composite material with low crystallization rate and good melt flowability, while maintaining good heat aging resistance, suitable for parts with complex structure, good appearance and heat aging resistance.

[0004] This invention is achieved through the following technical solution: A flame-retardant polyamide composite material, by weight, comprises the following components: 45-52 parts of polyamide resin; 0.5-2 parts of pentabromobenzyl polyacrylate; 17-30 parts flame retardant; 10-50 parts glass fiber; The polyamide resin is a blend of crystalline polyamide and amorphous polyamide, with a weight ratio of crystalline polyamide:amorphous polyamide = (1.09-1.92):1; and the flame retardant is a blend of high molecular weight brominated flame retardant and antimony white, with a weight ratio of high molecular weight brominated flame retardant:antimony white = (3-9):1.

[0005] The weight-average molecular weight of polypentabromobenzyl acrylate is generally between 30,000 and 80,000, and it is a high molecular weight brominated flame retardant. The polyamide resin can be in parts by weight of 45, 46, 47, 48, 49, or 50.

[0006] The weight parts of poly(pentabromobenzyl acrylate) can be 0.5 parts, 0.8 parts, 1.1 parts, 1.3 parts, 1.5 parts, 1.8 parts, or 2 parts.

[0007] The flame retardant can be in quantities of 17, 19, 21, 23, 25, 27, or 30 parts.

[0008] The fiberglass can be in quantities of 10 parts, 20 parts, 30 parts, 40 parts, or 50 parts.

[0009] In the flame-retardant polyamide composite material of the present invention, the polyamide resin accounts for not less than 30 wt% of the total weight.

[0010] The crystalline polyamide is selected from at least one of PA66, PA56, PA6, PA610, and PA612; the amorphous polyamide is selected from PA6I / 6T.

[0011] The crystallinity range of crystalline polyamides is 16-50%.

[0012] The mass ratio of 6I to 6T in PA6I / 6T ranges from 6.5:3.5 to 8:2.

[0013] Preferably, the content of pentabromobenzyl polyacrylate is 0.9-1.5 parts.

[0014] Preferably, the ratio of crystalline polyamide to amorphous polyamide is (1.15-1.3):1.

[0015] This invention does not have any particular limitation on polyamides; the purpose of this invention can be achieved by using crystalline polyamides and / or amorphous polyamides with a density of 1.0-1.2 g / cm³.

[0016] Antimony white is antimony trioxide.

[0017] The aforementioned high-molecular-weight brominated flame retardant is selected from at least one of brominated polystyrene and polybrominated polystyrene. Brominated polystyrene is obtained by bromination of polystyrene resin, while polybrominated polystyrene is obtained by polymerization of brominated styrene monomers.

[0018] The cross-section of the glass fiber can be circular or flat, but flat glass fiber is preferred to further improve fiber float.

[0019] The product also includes 0-3 parts by weight of additives, wherein the additives are selected from at least one of antioxidants, lubricants, and UV resistant agents.

[0020] Antioxidants can be: 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene; 2,5-di-tert-butyl-4-hydroxybenzyl dimethylamine; diethyl-3,5-di-tert-butyl-4-hydroxybenzyl phosphate; stearyl-3,5-di-tert-butyl-4-hydroxybenzyl phosphate; 3,5-di-tert-butyl-4-hydroxyphenyl-3,5-distearate-thiotriazolylamine; 2,6-di-tert-butyl-4-hydroxymethylphenol; 2,4-di-(n-octylthio)-6-(4-hydroxy-3,5-di-tert-butylglycerol allyl ether)-1,3,5-triazine; N,N'-hexamethylene di( 3,5-Di-tert-butyl-4-hydroxy-hydrogenated cinnamamide; N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine; octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; pentaerythritol-tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; triethylene glycol-bis[3-(3,5-dimethyl-4-hydroxyphenyl)propionate]; triethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate]; 2,2'-thiodiethyl-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, etc.

[0021] The lubricant may be at least one of the following: stearate lubricant, fatty acid lubricant, and stearate ester lubricant; wherein the stearate lubricant is selected from at least one of calcium stearate, magnesium stearate, and zinc stearate; wherein the fatty acid lubricant is selected from at least one of fatty acids, fatty acid derivatives, and fatty acid esters; and wherein the stearate ester lubricant is selected from at least one of pentaerythritol stearate.

[0022] The preparation method of flame-retardant polyamide composite material includes the following steps: according to the formula, the components are mixed evenly, and granulated by extrusion through a twin-screw extruder, with a screw length-to-diameter ratio of 40~48:1, a screw barrel temperature of 220~270℃, and a screw speed of 200~450rpm, to obtain the flame-retardant polyamide composite material.

[0023] Flame-retardant polyamide composites are used in the manufacture of electronic and electrical components.

[0024] The present invention has the following beneficial effects: This invention utilizes a specific blend of crystalline and amorphous polyamides. The amorphous polyamide molecular chains can insert into the crystalline polyamide molecular chains, thereby affecting the regularity of the crystalline molecular chains, reducing the crystallization temperature and rate, and increasing melt flowability. In contrast, glass fiber reinforced systems cool rapidly on the mold surface during injection molding, leading to severe fiber floating. When the material crystallizes slowly and has good melt flowability, the mold surface exhibits better replication and less fiber floating, making it suitable for injection-molded parts with complex structures. Pentabromobenzyl polyacrylate, as a surface modifier, can disrupt the hydrogen bonds between polyamide molecular chains and form hydrogen bonds with crystalline polyamide molecular chains, further reducing the material's crystallization temperature. This significantly improves the appearance and fiber floating problem of brominated flame-retardant reinforced PA materials during injection molding, while maintaining good material thermal stability, resulting in a substantial improvement in the material's appearance. Detailed Implementation

[0025] 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.

[0026] The raw materials used in this invention are sourced from the following sources: PA66: PA66 EP-158, Zhejiang Huafeng Group; PA56: Ecopent® 1273, purchased from Shanghai Kaisa; PA6: PA6 HY-2500A, Jiangsu Haiyang Chemical Fiber Co., Ltd.; PA610: PA610 F150, Shandong Guangyin; PA612: PA612 A120, Shandong Guangyin; PA6I / 6T-1: selar PA 3426, isophthalic acid and terephthalic acid in a mass ratio of 7:3, dupont; PA6I / 6T-2: TI1207, isophthalic acid and terephthalic acid in a mass ratio of 8:2, Shandong Guangyin; Brominated polystyrene: SAYTEX 5010, Albemarle, Inc., USA; Polybrominated styrene: PBS-64HW, Lanxess, USA; Brominated epoxy resin: F-2100, ICL Israel; Brominated PC: Powder-BC-58, Lanxess, USA; Polypentabromobenzyl acrylate: FR-1025, Israel ICL; Antimony trioxide: Flashstar Antimony Industry; Round fiberglass: Fiberglass ECS301CL-3, Chongqing International Composite Materials Co., Ltd.; Flat glass fiber: ECS301HP-3-M3 glass fiber, Chongqing International Composite Materials Co., Ltd.; Antioxidant: N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine (IRGANOX1098), BASF.

[0027] Lubricant: Stearyl stearate, LOXIOL G32, Corning, Germany.

[0028] Preparation method of flame-retardant polyamide composite material in the examples and comparative examples: The components are mixed evenly and extruded and granulated by a twin-screw extruder with a screw length-to-diameter ratio of 40:1, a barrel temperature of 220~270℃, and a screw speed of 200~450rpm to obtain the flame-retardant polyamide composite material.

[0029] Test methods: (1) Spiral length: Using an injection molding machine, the temperatures from the nozzle to the discharge port are 275℃, 270℃, 260℃, and 250℃ respectively. Medium pressure and medium speed are used to inject a 6.0×2.0mm thick spiral sample and measure the spiral length. The spiral length is mainly affected by the melt flowability and crystallization rate. The longer the spiral, the more suitable it is for injection molding of complex parts.

[0030] (2) Surface floating fiber: Using an injection molding machine, the temperatures from the nozzle to the discharge port are 275℃, 270℃, 260℃, and 250℃ respectively. Medium pressure and medium speed are used to inject a 100×100×2mm square plate. The white area on the surface of the square plate is observed (floating fiber appears as white in appearance). The less white area, the better the floating fiber effect.

[0031] (3) Flame retardancy: 0.75mm thick injection molded burning test strips were used to test the burning performance of the material using UL 94 standard.

[0032] (4) Thermal stability: Test TGA, 30-750℃, 20℃ / min, and observe the decomposition temperature when the material loses 5% of its weight.

[0033] Table 1: Formulation (parts by weight) and test results of flame-retardant polyamide composite materials in Examples 1-6 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 PA66 26.19 27.27 29.17 32.76 PA56 27.27 PA6 27.27 PA6I / 6T-1 23.81 22.73 20.83 17.24 22.73 22.73 Polypentabromobenzyl acrylate 1.2 1.2 1.2 1.2 0.5 1 Brominated polystyrene 18.75 18.75 18.75 18.75 22.5 18.75 antimony white 6.25 6.25 6.25 6.25 7.5 6.25 Flat fiberglass 30 30 30 30 10 20 antioxidants 0.5 0.5 0.5 0.5 0.5 0.5 Flame retardancy V-0 V-0 V-0 V-0 V-0 V-0 Helix length, mm 450 448 447 445 456 475 <![CDATA[White area mm 2 > 81 30 36 64 32 28 Thermal decomposition temperature, °C 350 351 352 352 356 354 As can be seen from Examples 1-4, when the preferred ratio of crystalline polyamide to amorphous polyamide is used, the surface of the part is smooth and flat with a small area of ​​whitening, indicating that there is less floating fiber.

[0034] Table 2: Formulation (parts by weight) and test results of flame-retardant polyamide composite materials in Examples 7-12 Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 PA66 27.27 27.27 27.27 27.27 PA610 27.27 PA612 27.27 PA6I / 6T-1 22.73 22.73 22.73 22.73 22.73 PA6I / 6T-2 22.73 Polypentabromobenzyl acrylate 1.5 2 1.2 1.2 1.2 1.2 Brominated polystyrene 15 12.75 22.5 18.75 18.75 Polybrominated styrene 18.75 antimony white 5 4.25 2.5 6.25 6.25 6.25 Flat fiberglass 40 50 30 30 30 Round glass fiber 30 antioxidants 0.5 0.5 0.5 0.5 0.5 0.5 Flame retardancy V-0 V-0 V-0 V-0 V-0 V-0 Helix length, mm 482 490 441 440 456 452 <![CDATA[Whitening area mm 2 > 35 56 30 72 42 45 Thermal decomposition temperature, °C 352 349 358 352 353 351 As can be seen from Examples 2 / 10, fewer surface fibers are present when flat glass fibers are preferred.

[0035] Table 2: Formulation (parts by weight) and test results of flame-retardant polyamide composite materials in Examples 13-16 Example 13 Example 14 Example 15 Example 16 PA66 27.27 27.27 27.27 27.27 PA6I / 6T-1 22.73 22.73 22.73 22.73 Polypentabromobenzyl acrylate 0.5 0.9 1.5 2 Brominated polystyrene 18.75 18.75 18.75 18.75 antimony white 6.25 6.25 6.25 6.25 Flat fiberglass 30 30 30 30 antioxidants 0.5 0.5 0.5 0.5 Flame retardancy V-0 V-0 V-0 V-0 Helix length, mm 432 441 440 437 <![CDATA[Whitening area mm 2 > 78 65 50 46 Thermal decomposition temperature, °C 354 353 348 346 As can be seen from Examples 2 / 13-16, when the preferred content range of polypentabromobenzyl acrylate is 0.9-1.5 parts, the spiral length is longer and the whitening area is smaller.

[0036] Table 4: Formulation (parts by weight) and test results of flame-retardant polyamide composites of Comparative Examples 1-6 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 PA66 22.12 34.37 27.27 27.27 27.27 27.27 PA6I / 6T-1 27.78 15.63 22.73 22.73 22.73 22.73 Polypentabromobenzyl acrylate 1.2 1.2 0 3 1.2 1.2 Brominated polystyrene 18.75 18.75 18.75 18.75 22.9 16.67 antimony white 6.25 6.25 6.25 6.25 2.1 8.33 Flat fiberglass 30 30 30 30 30 30 antioxidants 0.5 0.5 0.5 0.5 0.5 0.5 Flame retardancy V-0 V-0 V-0 V-0 V-1 V-1 Helix length (mm) 452* 425 420 430 438 452 <![CDATA[Whitening area mm 2 > 450 400 504 42 96 36 Thermal decomposition temperature, °C 352 352 356 341 356 354 *Indicates poor demolding of the injection molding spiral. As can be seen from the above embodiments, the flame-retardant polyamide composite material of the present invention can achieve V-0 flame retardancy, a helix length > 440 mm, and a whitening area < 100 mm². 2 Thermal decomposition temperature > 348℃.

[0037] As can be seen from Comparative Example 1, it is not always better to have a higher proportion of amorphous polyamide. When the content of amorphous polyamide is too high, although the spiral length is long enough, it is difficult to demold and there are more floating fibers on the surface.

[0038] As shown in Comparative Example 2, if the proportion of amorphous polyamide is too low, the spiral length is low and there are more surface fibers.

[0039] As shown in Comparative Example 3, if pentabromobenzyl polyacrylate is not added, the crystallization rate of the composite material is still too fast, the helix length is short, and there are many floating fibers.

[0040] As shown in Comparative Example 4, if the content of pentabromobenzyl polyacrylate is too high, it will also greatly reduce the thermal decomposition temperature.

[0041] As can be seen from Comparative Example 5 / 6, if the ratio of flame retardant is not within the scope of this invention, the flame retardancy will not reach V0, and there will be more floating fibers when the antimony white content is too low.

[0042] Table 5: Formulation (parts by weight) and test results of flame-retardant polyamide composites of Comparative Examples 7-8 Comparative Example 7 Comparative Example 8 PA66 27.27 27.27 PA6I / 6T-1 22.73 22.73 Polypentabromobenzyl acrylate 1.2 1.2 Brominated epoxy resin 18.75 Brominated PC 18.75 antimony white 6.25 6.25 Flat fiberglass 30 30 antioxidants 0.5 0.5 Flame retardancy V-0 N / A Helix length (mm) 432 N / A <![CDATA[White area mm 2 > 348 N / A Thermal decomposition temperature, °C 328 N / A Comparative Example 8 could not be produced.

[0043] As shown in Comparative Example 7, if brominated epoxy resin is used instead of brominated polystyrene, the thermal decomposition temperature is low, and the processing performance is poor with more floating fibers.

Claims

1. A flame-retardant polyamide composite, characterized in that, By weight parts, including the following components: Polyamide resin 45-52 parts; Polyacrylic acid pentabromobenzyl ester 0.5-2 parts; Flame retardant 17-30 parts; Glass fiber 10-50 parts; The polyamide resin is compounded by crystalline polyamide and amorphous polyamide, and the weight ratio is crystalline polyamide: amorphous polyamide = (1.09-1.92):1; The flame retardant is a compound of high molecular bromine flame retardant / antimony white, and the weight ratio is high molecular bromine flame retardant: antimony white = (3-9):

1.

2. The flame retardant polyamide composite according to claim 1, characterized in that, The crystalline polyamide is selected from at least one of PA66, PA56, PA6, PA610, PA612; the amorphous polyamide is selected from PA6I / 6T.

3. The flame retardant polyamide composite according to claim 1, characterized in that, The content of polyacrylic acid pentabromobenzyl ester is 0.9-1.5 parts.

4. The flame retardant polyamide composite of claim 1, wherein, Crystalline polyamide: amorphous polyamide = (1.15-1.3):

1.

5. The flame retardant polyamide composite of claim 1, wherein, The high molecular bromine flame retardant is selected from at least one of brominated polystyrene and polybrominated styrene.

6. The flame retardant polyamide composite of claim 1, wherein, The glass fiber is selected from flat glass fiber.

7. The flame retardant polyamide composite of claim 1, wherein, By weight parts, 0-3 parts of auxiliary are further included, and the auxiliary is selected from at least one of antioxidant, lubricant and ultraviolet resistant agent.

8. Process for the production of a flame-retardant polyamide composite material according to any one of claims 1 to 7, characterized in that, Including the following steps: according to the proportion, mix each component uniformly, extrude and granulate through double screw extruder, the length-diameter ratio of screw is 40~48:1, the barrel temperature is 220~270℃, the screw rotation speed is 200~450rpm, and the flame retardant polyamide composite material is obtained.

9. Use of a flame-retardant polyamide composite material according to any one of claims 1 to 7, characterized in that, For preparing electronic and electrical parts. For preparing electronic and electrical parts.