Polyamide material as well as preparation method and application thereof

Abstract

The invention belongs to the field of polyamide materials, and particularly discloses a polyamide material as well as a preparation method and application thereof. The ethylene-vinyl acetate copolymer in the polyamide material improves the compatibility of polyamide matrix resin and other components, improves the melt fluidity of the material and improves the appearance performance of the material; meanwhile, the metal oxide is respectively matched with the flame retardant and the antistatic agent, so that the flame retardant property and the antistatic property are obviously improved, the melt flowability of the material is further improved, the appearance performance of the material is improved, and the loss of the flame retardant property caused by the existence of the ethylene-vinyl acetate copolymer is reduced to a certain extent; therefore, the material has excellent flame retardant property, antistatic property and good flowability and appearance performance at the same time.

Description

Technical Field

[0001] This invention belongs to the field of polyamide materials, specifically relating to a polyamide material, its preparation method, and its application. Background Technology

[0002] Polyamide (PA) is the world's first synthetic fiber, a general term for thermoplastic resins containing repeating amide groups in their molecular backbone. Polyamide possesses excellent mechanical and electrical insulation properties, good toughness, and excellent heat resistance, weather resistance, and abrasion resistance, making it widely used in the automotive, electronics, and consumer electronics industries. However, the poor flame retardant properties of pure polyamide limit its application. Flame retardants are typically added to polyamide to improve its flame retardancy; glass fibers are also commonly added as reinforcing fillers, and antistatic agents are added to impart high strength, high rigidity, and antistatic properties. However, the poor compatibility of polyamide with flame retardants, glass fibers, and antistatic agents leads to a decrease in the overall melt flowability of the material, resulting in appearance defects such as fiber floating and whitening, limiting its application in parts requiring aesthetically pleasing finishes; it also negatively impacts flame retardancy and antistatic properties, making it impossible to simultaneously and effectively improve flame retardancy, antistatic properties, and appearance. Summary of the Invention

[0003] In view of the shortcomings of the existing polyamide materials, which cannot simultaneously possess flame retardant, antistatic, and appearance properties, the present invention will provide a polyamide material, its preparation method, and its application.

[0004] To achieve the above objectives, the technical solutions include the following three aspects.

[0005] In a first aspect, the present invention provides a polyamide material comprising the following components in parts by weight: 14-26 parts of polyamide resin, 14-26 parts of antistatic agent, 14-21 parts of flame retardant, 4.5-15.5 parts of ethylene-vinyl acetate copolymer, 19-41.5 parts of glass fiber, and 0.4-6.2 parts of metal oxide; wherein the antistatic agent comprises polyethylene oxide copolymer.

[0006] In the polyamide material of the present invention, the ethylene-vinyl acetate copolymer improves the compatibility between the polyamide matrix resin and the other components, enhances the melt flowability of the material, and improves the appearance properties of the material. At the same time, the metal oxides are combined with the flame retardant and the antistatic agent respectively, which significantly improves the flame retardant and antistatic properties, further enhances the melt flowability of the material, improves the appearance properties of the material, and to a certain extent reduces the loss of flame retardant properties caused by the presence of the ethylene-vinyl acetate copolymer. Overall, the material has excellent flame retardant properties, antistatic properties, good flowability, and good appearance properties.

[0007] Preferably, the polyamide material comprises the following components in parts by weight: 15-25 parts polyamide resin, 15-25 parts antistatic agent, 15-20 parts flame retardant, 5-15 parts ethylene-vinyl acetate copolymer, 20-40 parts glass fiber, and 0.5-6 parts metal oxide.

[0008] Preferably, based on the mass of the polyamide material, the mass percentage of the polyamide resin is not less than 15%, and more preferably not less than 17%.

[0009] Preferably, based on the mass of the polyamide material, the mass percentage of the glass fiber is 26%-32%, specifically 26%, 27%, 28%, 29%, 30%, 31%, 32%, etc., as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range.

[0010] Preferably, the polyamide resin comprises aliphatic polyamide and / or aromatic polyamide. Specifically, the aliphatic polyamide comprises at least one of PA66, PA610, PA612, PA1010, PA1012, PA1212, PA6, PA7, PA11, or PA12. The aromatic polyamide may be a semi-aromatic polyamide (PPA), which comprises at least one of PA9T, PA6T, and PA10T.

[0011] More preferably, the intrinsic viscosity of the polyamide resin is 1.5 dL / g-5 dL / g, more preferably 2-2.8 dL / g, and the viscosity is tested using 96% concentrated sulfuric acid as the solvent according to ISO 307 2019 standard.

[0012] Preferably, based on the mass of the polyamide material, the mass percentage of the antistatic agent is 15%-25%, specifically 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, etc., as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0013] The polyethylene oxide copolymer of the present invention is a copolymer of polyethylene oxide and other polymer monomers. Preferably, the polyethylene oxide copolymer includes at least one of polyethylene oxide and polyethylene terephthalate block copolymer, polyethylene oxide and polyethylene oxide copolymer, and polyethylene oxide and polyamide copolymer; and / or, the polyethylene oxide copolymer includes a copolymer of polyethylene oxide, polyethylene oxide and polyamide.

[0014] Preferably, the copolymer of polyethylene oxide and polypropylene oxide has a melt index of 50-100 g / 10 min when tested at 200°C and 5 kg according to ISO 1133-2022 standard. Preferably, the copolymer of polyethylene oxide and polyamide has a melt index of 50-100 g / 10 min when tested at 230°C and 5 kg according to ISO 1133-2022 standard.

[0015] Preferably, based on the mass of the polyamide material, the mass percentage of the flame retardant is 15%-20%, specifically 15%, 16%, 17%, 18%, 19%, 20%, etc., as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range.

[0016] Preferably, the flame retardant includes a brominated flame retardant.

[0017] More preferably, the brominated flame retardant includes at least one of polybrominated styrene, brominated polystyrene, or decabromodiphenyl ethane.

[0018] Preferably, it further includes 1-5 parts by weight of a flame retardant synergist, wherein the flame retardant synergist includes at least one of antimony oxide, magnesium hydroxide, zinc borate, or magnesium borate.

[0019] Preferably, based on the mass of the polyamide material, the mass percentage of the ethylene-vinyl acetate copolymer is 5%-15%, specifically 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, etc., as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0020] Preferably, the vinyl acetate content in the ethylene-vinyl acetate copolymer is 15%-40% by mass, specifically 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, etc., as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range.

[0021] More preferably, the vinyl acetate content in the ethylene-vinyl acetate copolymer is 18%-28% by mass.

[0022] The method for testing the vinyl acetate (VA) content in EVA according to ISO 8985:2022 includes the following steps: dissolve the sample in xylene, add potassium hydroxide-ethanol solution to hydrolyze the acetate groups, then add excess sulfuric acid or hydrochloric acid, using phenolphthalein as an indicator, and titrate the excess acid with sodium hydroxide standard solution. Calculate the mass percentage of vinyl acetate in the sample based on the volume of sodium hydroxide standard solution consumed.

[0023] Preferably, the glass fiber has an average diameter of 10-13 μm and an average length of 1-5 mm. The average diameter of the glass fiber can be 10 μm, 11 μm, 12 μm, 13 μm, etc., and the average length can be 1 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 5 mm, etc., as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0024] This invention uses scanning electron microscopy to test the average diameter and average length of glass fibers.

[0025] Preferably, the metal oxide includes at least one of zinc oxide, tin oxide, doped zinc oxide, iron oxide, copper oxide, indium oxide, or doped indium oxide.

[0026] Further preferably, the metal oxide is doped zinc oxide and doped indium oxide, and the mass ratio of the doped zinc oxide and doped indium oxide is (0.3-5):1. More specifically, it can be 0.3:1, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, etc., as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0027] More preferably, the doped zinc oxide contains 0.5%-3% aluminum oxide by mass.

[0028] More preferably, the indium oxide doped with 1%-15% tin oxide by mass.

[0029] Preferably, the polyamide material further includes 0.5-2 parts by weight of an additive, which includes a lubricant.

[0030] More preferably, the lubricant includes at least one of silicone oils, esters, amides, polyethylene, stearic acid, and fatty acid lubricants.

[0031] Secondly, the present invention provides a method for preparing the polyamide material, comprising the following steps: S1. Mix the raw materials except for glass fiber to obtain a premix; S2: The premix is ​​melt-blended, then glass fiber is added, and then extruded and granulated to obtain the polyamide material.

[0032] Preferably, the melt blending temperature is 220-280℃.

[0033] Thirdly, the present invention also provides an application of the polyamide material described above in the preparation of dustproof shells and mining equipment, and more specifically, it can be applied to electrical control boxes or medical kits in mines.

[0034] Compared with the prior art, the present invention has the following beneficial effects: the ethylene-vinyl acetate copolymer in the polyamide material of the present invention improves the compatibility between the polyamide matrix resin and the other components, improves the melt flowability of the material and improves the appearance performance of the material; at the same time, the metal oxides cooperate with the flame retardant and antistatic agent respectively, which significantly improves the flame retardant performance and antistatic performance, further improves the melt flowability of the material and improves the appearance performance of the material, and to a certain extent reduces the loss of flame retardant performance caused by the presence of ethylene-vinyl acetate copolymer. In summary, the material has excellent flame retardant performance, antistatic performance and good flowability and appearance performance. Detailed Implementation

[0035] To better illustrate the purpose, technical solution, and advantages of the present invention, specific embodiments will be used to further explain the invention below. Unless otherwise specified, all raw materials used in the embodiments and comparative examples of the present invention are commercially available, and the same raw materials were used in all parallel experiments.

[0036] Raw material information: (1) Polyamide resin: PA-1: PA6 M2000, intrinsic viscosity is 2.0 dL / g, Xinhui Meida; PA-2: PA6 M2400, intrinsic viscosity is 2.4 dL / g, Xinhui Meida; PA-3: PA6 M2800, intrinsic viscosity is 2.8 dL / g, Xinhui Meida.

[0037] (2) Glass fiber: Fiberglass 1: Round glass fiber: ECS10-3.0-T435N, average diameter 10μm, average length 3.0mm, Taishan Fiberglass; Fiberglass 2: Round glass fiber: ECS11-3.0-T435N, average diameter 11μm, average length 3.0mm, Taishan Fiberglass; Fiberglass 3: Round glass fiber: ECS13-3.0-T435N, average diameter 13μm, average length 3.0mm, Taishan Fiberglass.

[0038] (3) Flame retardant: Flame retardant-1: Brominated polystyrene, BPS 7010, Shandong Tianyi.

[0039] Flame retardant-2: Decabromodiphenyl ethane, commercially available.

[0040] (4) Antistatic agent: Antistatic agent 1: The main component is a copolymer of polyethylene oxide and polypropylene oxide, 6040, with a melt index of 80g / 10min at 200℃ and 5kg, from Zhejiang Xinyuan; Antistatic agent 2: a copolymer of polyethylene oxide and polyamide 6, AS5502, with a melt index of 70g / 10min at 230℃ and 5kg, produced by Xuyang Technology; Antistatic agent 3: Polyethylene glycol, PEG-4000, Lotte Chemical.

[0041] (5) Metal oxides: Metal oxide 1: Doped zinc oxide (doped with 1% aluminum oxide by mass), HN-J50L, Hangzhou Hengna; Metal oxide 2: Indium oxide doped with LF-ITO-N20, Luofei Nano, with tin oxide doped into indium oxide, the mass percentage of tin oxide doped is 10%; Metal oxide 3: Copper oxide, HN-CO1, Hangzhou Hengna.

[0042] (6) Compatibilizer: EVA-1: VA content is 18% by mass, Elvax460, Dow Chemical; EVA-2: VA content is 28% by mass, Elvax 260A, Dow Chemical; EVA-3: VA content is 40% by mass, Elvax 40L-03, Dow Chemical. Maleic anhydride-grafted PP, CMG9801, Jia Yi Rong.

[0043] (7) Lubricant: Stearic acid, RBW300, Clariant; Examples 1-17 and Comparative Examples 1-5 A method for preparing a polyamide material includes the following steps: (1) Weigh the raw materials according to the raw material components and their weight proportions in Table 1-2; (2) Then, the polyamide resin, antistatic agent, flame retardant, optional flame retardant synergist, compatibilizer, metal oxide and optional lubricant are mixed evenly in a high-speed mixer to obtain a premix. (3) Add the premixed material to a twin-screw extruder for melt blending, then feed the glass fiber through a side feeder, melt blend and disperse it evenly in the extruder, and extrude and granulate to obtain polyamide material; wherein, the screw length-to-diameter ratio of the twin-screw extruder is 40:1, the screw barrel temperature is selected as 270-250-250-250-250-260-280℃, and the screw speed is selected as 200rpm.

[0044] Table 1 Table 2 The polyamide materials prepared in the above examples and comparative examples were subjected to performance tests. The specific test methods and qualification requirements are as follows: (1) Surface resistance: The polyamide materials prepared in the examples and comparative examples were injection molded into square plates of 100×100×3mm. The surface resistance was tested according to IEC 62631-3-2:2023 using a HIOKI high resistance meter model SM7110. The surface resistance was <10 Ω·cm. 9 Ω is considered acceptable; (2) Flame retardancy: The polyamide materials prepared in the examples and comparative examples were injection molded into samples with a thickness of 3 mm. The 5VA flame retardancy rating was tested according to the UL94-2023 standard. If the sample passed the 5VA flame retardancy rating test, it was considered to meet the requirements. If it failed, it was considered not to meet the requirements. (3) Spiral length: Under the same injection molding parameters, the polyamide materials prepared in the examples and comparative examples were injection molded into mosquito coil-like products, and the lengths that different materials could fill were compared. The molds used for the injection-molded mosquito coil-like structures were designed with 5mm increments; intermediate increments were inconvenient to measure, so the longest increment actually exceeded was recorded as the spiral length. Better flowability resulted in a longer spiral length; a spiral length greater than 500mm was considered acceptable. (4) Appearance performance: The polyamide materials prepared in the examples and comparative examples are injection molded into strips of the same size. The appearance of the strips is observed. If there are no floating fibers on the appearance of the strip, it is considered excellent. If there are very slight or very small floating fibers on the surface, it is considered good. If there are obvious and large amounts of floating fibers on the surface and the surface is rough, it is considered poor. When the appearance performance reaches good, it is considered qualified.

[0045] The test results are shown in Table 3.

[0046] Table 3 As can be seen from the above embodiments, the surface resistivity of the polyamide material of the present invention is <10. 9Ω, meeting the 5VA flame retardant rating of 3mm, with excellent appearance performance and a spiral diameter greater than 500mm. The material combines low surface resistance, excellent flame retardant performance, high fluidity, and good appearance.

[0047] As can be seen from Examples 1-3, as the viscosity of PA increases, the antistatic and flame retardant properties remain basically unchanged, while the material flowability and appearance properties decrease slightly. However, the materials can still meet the requirements of a spiral length > 500 mm and a good appearance.

[0048] As can be seen from Examples 2 and 4-5, as the average diameter of the glass fiber increases, the fluidity of the material decreases slightly, but the spiral length is >500mm, which basically meets the requirements for fluidity. At the same time, the antistatic properties, appearance and flame retardancy of the material remain basically unchanged.

[0049] As can be seen from Examples 2 and 6, using copolymers of polyethylene oxide and polypropylene oxide, or copolymers of polyethylene oxide and polyamide 6, as the antistatic agent in the system of the present invention can meet the requirement of surface resistance <10 Ω·cm. 9 The requirements are as follows. Furthermore, analysis of Comparative Example 1 shows that increasing the flowability of the copolymer antistatic agent system containing polyethylene oxide and polypropylene oxide slightly decreases. However, compared to other antistatic agents such as polyethylene glycol, its compatibility with the system is poor, resulting in not only less effective antistatic properties but also a significant reduction in flame retardant and appearance properties. However, the two types of antistatic agents described in this invention exhibit good compatibility with the polyamide matrix resin and have no impact on the flame retardant and appearance properties of the material.

[0050] As can be seen from Examples 2 and 7-11, adding metal oxides can significantly improve antistatic properties, flowability, flame retardancy, and appearance. At the same time, the antistatic properties of the material are better when using a combination of doped zinc oxide and doped indium oxide compared to using a single metal oxide or any of the above two metal oxides combined with other oxides.

[0051] Compared to Example 2, Comparative Examples 2, 3, and 5 all contained antistatic agents. However, Comparative Example 3 contained EVA but no metal oxides, Comparative Example 4 contained metal oxides but no EVA, and Comparative Example 5 contained neither EVA nor metal oxides. Furthermore, the flow properties, appearance properties, and flame retardant properties of Comparative Examples 2, 3, and 5 were all poor. It is evident that the flow properties, appearance properties, and flame retardant properties are poor even in the presence of antistatic agents and the absence of metal oxides and EVA. Moreover, using only EVA or metal oxides cannot significantly improve these properties. Only the combination of metal oxides and EVA can significantly improve the system's compatibility and molecular entanglement, achieving the goal of simultaneously improving the flow properties, appearance properties, and flame retardant properties of materials in the presence of antistatic systems.

[0052] As can be seen from Examples 2, 12-13 and Comparative Example 3, adding EVA can improve antistatic properties, flowability, appearance properties and flame retardant properties; as the content of EA in EVA increases, the antistatic properties remain basically unchanged, the degree of molecular chain entanglement between EVA and other substances increases, and the appearance properties and flowability properties decrease slightly, but still meet the basic requirements; and combined with the case of Comparative Example 4 using a compatibilizer other than EVA, maleic anhydride grafted PP cannot play a role in improving the compatibility of the system of the present invention, thereby failing to improve other properties.

[0053] As can be seen from Examples 2 and 14-15, increasing the amount of EVA will slightly increase the antistatic properties, appearance properties and flow properties of the material. However, it should not be too much, otherwise it will cause a decrease in the flow properties and appearance properties of the material.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A polyamide material, characterized in that, It comprises the following components in parts by weight: 14-26 parts polyamide resin, 14-26 parts antistatic agent, 14-21 parts flame retardant, 4.5-15.5 parts ethylene-vinyl acetate copolymer, 19-41.5 parts glass fiber, and 0.4-6.2 parts metal oxide; wherein the antistatic agent includes polyethylene oxide copolymer.

2. The polyamide material as described in claim 1, characterized in that, The vinyl acetate content in the ethylene-vinyl acetate copolymer is 15%-40% by mass.

3. The polyamide material as described in claim 1, characterized in that, Includes at least one of the following A and B: A. The polyamide resin includes at least one of PA66, PA610, PA612, PA1010, PA1012, PA1212, PA6, PA7, PA11 or PA12; B. The polyethylene oxide copolymer includes at least one of polyethylene oxide and polyethylene terephthalate block copolymer, polyethylene oxide and polyethylene oxide copolymer, and polyethylene oxide and polyamide copolymer.

4. The polyamide material as described in claim 1, characterized in that, The viscosity of the polyamide resin is 1.5 dL / g to 5 dL / g.

5. The polyamide material as described in claim 1, characterized in that, The glass fibers have an average diameter of 10-13 μm and an average length of 1-5 mm.

6. The polyamide material as described in claim 1, characterized in that, The flame retardant includes a brominated flame retardant; the brominated flame retardant includes at least one of polybrominated styrene, brominated polystyrene, or decabromodiphenyl ethane.

7. The polyamide material as described in claim 1, characterized in that, The metal oxide includes at least one of zinc oxide, tin oxide, doped zinc oxide, iron oxide, copper oxide, indium oxide, or doped indium oxide.

8. The polyamide material as described in claim 1, characterized in that, It also includes 0.5-2 parts by weight of additives, including lubricants.

9. A method for preparing the polyamide material according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Mix the raw materials except for glass fiber to obtain a premix; S2: The premix is ​​melt-blended, glass fiber is added, and then extruded and granulated to obtain the polyamide material.

10. The application of the polyamide material according to any one of claims 1-8 in the preparation of dustproof shells and mining equipment.

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