A nylon composite material and its preparation method and application

Abstract

A nylon composite material comprises the following components, by weight: 50-80 parts nylon resin; 10-20 parts polyphenylene ether resin; 2-10 parts polyether polyamide elastomer; 15-25 parts brominated polystyrene; and 3-8 parts flame retardant synergist. The brominated polystyrene has a weight-average molecular weight of 180,000-300,000; and the polyether polyamide elastomer has a Shore hardness of D38-D70. The present invention utilizes amorphous polymer PPE and the polyether polyamide elastomer as weld line adhesives, significantly improving the low weld line strength disadvantage of brominated flame-retardant nylon composite materials.

Description

Technical Field

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

[0002] Nylon resins possess excellent mechanical, barrier, heat, wear, and chemical resistance. Their composite materials are widely used in the machinery manufacturing industry, industrial connectors, power tools, electronics, and transportation. Across these diverse applications, there is an increasing demand for flame-retardant materials. Environmentally friendly bromine-based flame retardants, due to their high flame retardancy, high glow-wire properties, frosting resistance, easy coloring, and excellent mechanical properties, currently represent the largest and most widely used category of flame-retardant nylon products.

[0003] The issue of weld lines in injection molded products has always been a challenge in the industry, especially for products with complex structures such as round holes, squares, and irregular polygons. Whether single-point or multi-point injection molding is used, weld lines are easily formed where different melts meet, which can have a negative impact on the product. Because the material strength at the weld line is weak, it is prone to defects and material failure during product use. This is especially true for metal inserts, where the different thermal expansion coefficients of polymer and metal materials can generate internal stress at the weld line, making defects more likely to form.

[0004] The existing technology mainly improves the weld mark strength through the following methods:

[0005] CN 110733159A uses a special injection mold to obtain a spray-free plastic product without weld line defects. This method places extremely high demands on the injection mold and supporting equipment, requiring the mold to be heated and cooled at extremely high speeds. General products cannot meet this special mold requirement.

[0006] CN 105419291 B uses a composite of a styrene-acrylonitrile-glycidyl methacrylate random copolymer and a peroxide-grafted styrene-acrylonitrile copolymer as a compatibilizer to prepare a PC / ABS alloy with excellent weld line appearance and high strength. CN 109535682 A uses an ethylene copolymer compatibilizer to improve the weld line strength of a polyethylene / polycarbonate alloy. Such solutions are more commonly used in alloy systems.

[0007] However, for brominated flame retardant systems, especially brominated polystyrene flame retardants (BPS flame retardants) with good thermal stability, the base material of BPS flame retardants is styrene resin, which is a non-crystalline, non-polar polymer material. It is not compatible with crystalline nylon resins containing amide bond polar groups. In addition, the difference in molecular weight of flame retardants leads to low weld line strength of BPS brominated flame retardant nylon composite materials.

[0008] For reinforced systems, glass fibers tend to align along the flow direction during injection molding, forming a certain orientation. However, when the melt encounters an obstruction during flow, the glass fiber alignment changes, aligning perpendicularly to the flow direction, which reduces the material's strength in this direction. When the melt encounters an obstruction and is split into two or more streams that then rejoin, the front end of the melt cools faster, resulting in poorer fusion at the weld line and a decrease in strength. Summary of the Invention

[0009] The object of the present invention is to overcome the above technical defects and provide a flame retardant nylon composite material with high weld mark strength.

[0010] The present invention is achieved through the following technical solutions:

[0011] A nylon composite material, comprising the following components in parts by weight:

[0012] 50-80 parts of nylon resin;

[0013] 10-20 parts of polyphenylene ether resin;

[0014] 2-10 parts of polyether polyamide elastomer;

[0015] 15-25 parts of brominated polystyrene;

[0016] 3-8 parts of flame retardant synergist;

[0017] The weight average molecular weight of the brominated polystyrene is 180,000-300,000;

[0018] The Shore hardness of polyether polyamide elastomer is 38D-70D, and is tested according to ISO 868, with the value recorded after 15 seconds.

[0019] The weight average molecular weight of the polyphenylene ether resin of the present invention is in the range of 10,000-30,000, preferably in the range of 14,000-25,000, and more preferably in the range of 17,000-21,000.

[0020] The monomer of the polyphenylene ether resin of the present invention is 2,6-dimethylphenol.

[0021] The weight average molecular weight of the polyphenylene ether resin is measured by gel permeation chromatography (GPC) using tetrahydrofuran as solvent.

[0022] The polyphenylene ether of the present invention is prepared by a homemade method or a commercially available product. The homemade method is as follows: a catalytic system consisting of toluene, copper chloride, and diethylamine is sequentially added to a reactor, and under stable oxygen supply conditions, a toluene solution of 2,6-dimethylphenol is added dropwise, and the reaction is carried out at 15-25°C for 10-120 minutes. The longer the reaction time, the higher the molecular weight. The weight-average molecular weight of the material is controlled according to the reaction time. When the target molecular weight is reached, acetic acid is added to terminate the experiment. The polymer is then separated by precipitation with anhydrous ethanol, dissolved in toluene, reprecipitated with wastewater ethanol, and dried in a vacuum oven to constant weight. The amine / copper molar ratio is preferably 30-40:1, and the molar ratio of 2,6-dimethylphenol to copper ion is preferably 30-40:1.

[0023] Preferably, the Shore hardness of the polyether polyamide elastomer is D50-D65, tested according to ISO 868, and the value is recorded after 15 seconds.

[0024] Polyether polyamide elastomer is a thermoplastic elastomer formed by polymerizing flexible polyether and hard polyamide. Its molecular structure contains numerous ether and amide bonds, giving it excellent compatibility with nylon resins and polyphenylene ether resins. The higher the content of hard polyamide segments in a polyether polyamide elastomer, the higher its Shore hardness.

[0025] The flame retardant synergist is selected from antimony compounds, such as at least one of antimony trioxide and sodium antimonate.

[0026] The nylon resin is selected from at least one of the polyamide resins selected from aliphatic polyamide resins, semi-aromatic polyamide resins, and polylactam resins.

[0027] The aliphatic polyamide resin is selected from PA66, PA46, PA610, PA612, PA56, PA510, PA512, PA910, PA912, PA913, PA914, PA915, PA616, PA936, PA1010, PA1012, PA1013, PA1014, PA1210, PA1212, PA1213, PA1214, PA614, PA613, PA615, PA616 and the like.

[0028] The semi-aromatic polyamide is selected from PA MXD6, PA10T, PA10T1010, PA10T66, PA6T, PA6T66, PA9T and the like.

[0029] The polylactam is selected from PA5, PA6, PA11, PA12 and the like.

[0030] By weight, it also includes 0-40 parts of reinforcing agent, which is selected from at least one of glass fiber and mineral filler; by weight, it also includes 0-2 parts of auxiliary agent, which is selected from at least one of antioxidant, lubricant and weathering agent.

[0031] The preparation method of the nylon composite material of the present invention comprises the following steps: uniformly mixing the components according to the proportion, and extruding and granulating the components through a twin-screw extruder to obtain the nylon composite material.

[0032] The present invention provides an application of the nylon composite material for preparing electronic and electrical parts, parts requiring metal inserts, and other parts with complex structures.

[0033] The present invention has the following beneficial effects:

[0034] The present invention utilizes high-molecular-weight brominated polystyrene to reduce the viscosity difference between the resin matrix and the flame retardant, thereby minimizing localized single-component enrichment, particularly flame retardant enrichment, and reducing the negative impact on the composite's mechanical strength. The introduction of PPE resin moderately reduces the crystallinity of the PA material without sacrificing nylon's inherent advantages, such as heat resistance, pressure-resistant solvents, and high strength. This reduces the cooling rate at the weld line, allowing for better fusion of the two melts. Furthermore, a polyether-type polyamide elastomer, characterized by a specific ratio (characterized by Shore hardness) of flexible polyether segments and rigid polyamide, enhances material toughness without requiring the addition of an interfacial compatibilizer. This allows for molecular-level dispersion of the elastomer with the nylon matrix resin and polyphenylene ether resin, further enhancing weld line strength. Even in the presence of a weld line, the weld line maintains excellent stress cracking properties. This significantly expands the application of flame-retardant nylon, particularly for complex structural products. DETAILED DESCRIPTION

[0035] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0036] Nylon 66: PA66 EP-158, Huafeng Group Co., Ltd.

[0037] Nylon 6: PA6 HY-2500A, Haiyang Technology Co., Ltd.;

[0038] Nylon 66 / 6: PA66 88X, Ascend Performance Materials Co., Ltd.;

[0039] The following polyphenylene ether was prepared in-house using the following method: Toluene as the solvent, a catalyst system consisting of copper chloride and diethylamine (at a molar ratio of amine to copper of 35:1) was sequentially added to a reactor. Under a stable oxygen supply, a toluene solution of 2,6-dimethylphenol (2,6-dimethylphenol:copper ion) was added dropwise. The molar ratio of 2,6-dimethylphenol to copper ion was 35:1. The reaction was allowed to proceed at 20°C for 10 minutes to 2 hours. Longer reaction times increase molecular weight, and the molecular weight of the material can be controlled by adjusting the reaction time. After the reaction period, acetic acid was added to terminate the experiment. The polymer was isolated by precipitation with anhydrous ethanol, dissolved in toluene, reprecipitated with wastewater ethanol, and dried in a vacuum oven to constant weight.

[0040] Polyphenylene ether A: reaction time about 27 min, weight average molecular weight 14000, homemade;

[0041] Polyphenylene ether B: reaction time about 33 min, weight average molecular weight 17500, homemade;

[0042] Polyphenylene ether C: reaction time about 40 min, weight average molecular weight 21000, homemade;

[0043] Polyphenylene ether D: reaction time about 45 min, weight average molecular weight 24000, homemade;

[0044] Polyphenylene ether E: reaction time about 20 min, weight average molecular weight 11000, homemade;

[0045] Polyphenylene ether F: reaction time about 60 min, weight average molecular weight 29000, homemade;

[0046] Brominated polystyrene A: BPS 7010, weight-average molecular weight 190,000, Shandong Tianyi Chemical Co., Ltd.

[0047] Brominated polystyrene B: XZ-6700, weight-average molecular weight 240,000, Shandong Brother Chemical Co., Ltd.

[0048] Brominated polystyrene C: SAYTEX HP-5010PST, weight-average molecular weight 4702, Yabao Chemical Co., Ltd.

[0049] Glass fiber: glass fiber ECS10-03-568H, China Jushi Co., Ltd.

[0050] Antimony trioxide: S-05N, Changde Chenzhou Antimony Products Co., Ltd.

[0051] Polyether polyamide elastomer 1: Pebax® Rnew 25R53 SP 01, hardness of Shore 22D (after 15 seconds), Arkema, France;

[0052] Polyether polyamide elastomer 2: Pebax® Rnew 35R53 SP 01, hardness of Shore 25D (after 15 seconds), Arkema, France;

[0053] Polyether polyamide elastomer 3: PEBAX® MH 2030, with a hardness of 40 Shore D (after 15 seconds), manufactured by Arkema, France;

[0054] Polyether polyamide elastomer 4: Pebax® Rnew 40R53 SP 01, hardness of Shore 39 D (after 15 seconds), Arkema, France;

[0055] Polyether polyamide elastomer 5: Pebax® Rnew 55R53 SP 01, with a hardness of Shore 51D (after 15 seconds), manufactured by Arkema, France;

[0056] Polyether polyamide elastomer 6: Pebax® Rnew 63R53 SP 01, hardness of Shore 56 D (after 15 seconds), Arkema, France;

[0057] Polyether polyamide elastomer 7: Pebax® Rnew 70R53 SP 01, hardness of Shore 62D (after 15 seconds), Arkema, France;

[0058] Polyether polyamide elastomer 8: Pebax® Rnew 72R53 SP 01, hardness of Shore 65 D (after 15 seconds), Arkema, France;

[0059] Polyether polyamide elastomer 9: Pebax® Rnew 80R53 SP 01, hardness of Shore 67D (after 15 seconds), Arkema, France;

[0060] Comparative toughening agent 1: Fusabond N493, maleic anhydride grafted low Tg ethylene copolymer, DuPont;

[0061] Comparative toughening agent 2: SEBS FG1901 GT, a linear triblock copolymer of styrene and ethylene / butylene, Kraton Corporation;

[0062] Comparative toughening agent 3: KT-7K, maleic anhydride grafted EPDM rubber, Shenyang Ketong Plastic Co., Ltd.

[0063] Embodiment and comparative example A method for preparing a flame-retardant nylon composite material with high weld mark strength: according to the ratio, the components are mixed evenly, and granulated by extrusion through a twin-screw extruder to obtain a flame-retardant nylon composite material with high weld mark strength, wherein the screw barrel temperatures of the extruder are 160°C, 250°C, 260°C, 260°C, 240°C, 230°C, 230°C, 240°C and 260°C, respectively, and the speed is set to 350rpm-450rpm.

[0064] Various test methods:

[0065] (1) Weld line strength: The weld line strength is measured using an ISO 527 standard tensile test mold with two inlet gates. During the injection molding process, the melt is filled from both ends to the middle, forming a weld line in the middle. The weld line strength is measured according to the ISO 527 tensile test method at a tensile rate of 10 mm / min, expressed in MPa.

[0066] (2) Flame retardant grade: The test is carried out in accordance with UL 94 standard, and the test specimen size is 125mm*13mm*1.6mm.

[0067] Table 1: Component contents and test results of high weld mark strength flame retardant nylon composite materials of Examples 1-6

[0068] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Nylon 66 50 Nylon 6 60 60 60 60 Nylon 66 / 6 80 Polyphenylene ether A 10 15 20 15 Polyphenylene ether B 15 Polyphenylene ether C 15 Brominated polystyrene A 15 25 Brominated polystyrene B 20 20 20 20 Polyether polyamide elastomer 3 5 2 10 4 4 4 Antimony trioxide 8 6 3 6 6 6 fiberglass 10 10 10 Flame retardant grade V-0 V-0 V-0 V-0 V-0 V-0 Weld mark strength MPa 61 66 64 75 79 81

[0069] Table 2: Component contents and test results of high weld mark strength flame retardant nylon composite materials of Examples 7-9

[0070] Example 7 Example 8 Example 9 Nylon 6 60 60 60 Polyphenylene ether D 15 Polyphenylene ether E 15 Polyphenylene ether F 15 Brominated polystyrene B 20 20 20 Polyether polyamide elastomer 3 4 4 4 Antimony trioxide 6 6 6 fiberglass 10 10 10 Flame retardant grade V-0 V-0 V-0 Weld mark strength MPa 77 73 72

[0071] It can be seen from Examples 4-9 that the weight average molecular weight of polyphenylene ether mainly affects the dispersibility and compatibility of polyphenylene ether in the resin matrix, and the weld mark strength is higher when the weight average molecular weight range is preferred.

[0072] Table 3: Component contents and test results of high weld mark strength flame retardant nylon composite materials of Examples 10-15

[0073] Example 10 Example 11 Example 12 Example 13 Example 14 Example 15 Nylon 6 60 60 60 60 60 60 Polyphenylene ether B 15 15 15 15 15 15 Brominated polystyrene B 20 20 20 20 20 20 Polyether polyamide elastomer types 4 5 6 7 8 9 Polyether polyamide elastomer content 4 4 4 4 4 4 Antimony trioxide 6 6 6 6 6 6 fiberglass 10 10 10 10 10 10 Flame retardant grade V-0 V-0 V-0 V-0 V-0 V-0 Weld mark strength MPa 73 81 81 84 80 77

[0074] It can be seen from Examples 4 / 10-15 that the weld mark strength is higher when the Shore hardness of the polyether polyamide elastomer is preferred.

[0075] Table 4: Component contents and test results of flame retardant nylon composite materials of Comparative Examples 1-6

[0076] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Nylon 6 60 60 60 60 60 60 Polyphenylene ether A 0 5 30 15 15 15 Brominated polystyrene B 20 20 20 20 20 Brominated polystyrene C 20 Polyether polyamide elastomer 3 4 4 4 4 0 15 Antimony trioxide 6 6 6 6 6 6 fiberglass 10 10 10 10 10 10 Flame retardant grade V-2 V-0 V-0 V-0 V-0 V-0 Weld mark strength MPa 43 47 41 38 42 45

[0077] It can be seen from Comparative Examples 1 / 2 that if no polyphenylene ether is contained or the content is too low, the weld mark strength is low.

[0078] It can be seen from Comparative Example 3 that when the polyphenylene ether content is too high, the weld mark strength is low.

[0079] It can be seen from Comparative Example 4 that the conventional low molecular weight brominated polystyrene has a low weld mark strength of the composite material due to its dispersibility.

[0080] It can be seen from Comparative Examples 5 and 6 that when the content of the polyether polyamide elastomer is too high or zero, the weld mark strength is too low.

[0081] Table 5: Component contents and test results of flame retardant nylon composite materials of Comparative Examples 7-11

[0082] Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Comparative Example 11 Nylon 6 60 60 60 60 60 Polyphenylene ether A 15 15 15 15 15 Brominated polystyrene B 20 20 20 20 20 Polyether polyamide elastomer 1 4 Polyether polyamide elastomer 2 4 Comparative toughening agent 1 4 Comparative toughening agent 2 4 Comparative toughening agent 3 4 Antimony trioxide 6 6 6 6 6 fiberglass 10 10 10 10 10 Flame retardant grade V-0 V-0 V-0 V-0 V-0 Weld mark strength MPa 46 50 35 37 40

[0083] It can be seen from Example 4 and Comparative Examples 7-8 that if the Shore hardness of the polyether polyamide elastomer is not within the range of the present invention, the weld mark strength of the composite material is too low.

[0084] It can be seen from Comparative Examples 9-11 that the toughening agents commonly used in nylon materials have low weld mark strength when applied to the system of the present invention.

Claims

1. A nylon composite material, characterized in that: Calculated by weight, it includes the following components: 50-80 parts of nylon resin; 10-20 parts of polyphenylene ether resin; 2-10 parts of polyether polyamide elastomer; 15-25 parts of brominated polystyrene; 3-8 parts of flame retardant synergist; The weight average molecular weight of the brominated polystyrene is 180,000-300,000; The Shore hardness of polyether polyamide elastomer is 38D-70D, and is tested according to ISO 868, with the value recorded after 15 seconds.

2. The nylon composite material according to claim 1, characterized in that The weight average molecular weight of the polyphenylene ether resin is in the range of 10,000-30,000.

3. The nylon composite material according to claim 2, characterized in that: The weight average molecular weight of the polyphenylene ether resin is in the range of 14,000-25,000.

4. The nylon composite material according to claim 3, characterized in that The weight average molecular weight of the polyphenylene ether resin is in the range of 17,000-21,000.

5. The nylon composite material according to claim 1, characterized in that The monomer of the polyphenylene ether resin is 2,6-dimethylphenol.

6. The nylon composite material according to claim 1, wherein The Shore hardness of the polyether polyamide elastomer is 50D-65D, and is tested according to ISO 868, with the value recorded after 15 seconds.

7. The nylon composite material according to claim 1, characterized in that The flame retardant synergist is selected from antimony compounds, and the antimony compound is selected from at least one of antimony trioxide and sodium antimonate.

8. The nylon composite material according to claim 1, characterized in that The nylon resin is selected from aliphatic polyamide resin and semi-aromatic polyamide resin.

9. The nylon composite material according to claim 1, characterized in that: The nylon resin is selected from polylactam resin.

10. The nylon composite material according to claim 1, characterized in that By weight, it also includes 0-40 parts of reinforcing agent, which is selected from at least one of glass fiber and mineral filler; by weight, it also includes 0-2 parts of auxiliary agent, which is selected from at least one of antioxidant, lubricant and weathering agent.

11. The method for preparing the nylon composite material according to any one of claims 1 to 10, characterized in that: The method comprises the following steps: uniformly mixing the components according to the proportion, and extruding and granulating the components through a twin-screw extruder to obtain a nylon composite material.

12. Use of the nylon composite material according to any one of claims 1 to 10, characterized in that: Used for the preparation of electronic and electrical parts and parts that require metal inserts.