MCA / PA6 flame-retardant composite material and preparation method thereof

Abstract

The invention is suitable for the technical field of MCA, and provides an MCA / PA6 flame-retardant composite material and a preparation method thereof. Comprising the following components in parts by weight: 50-60 parts of MCA, 15-20 parts of PA6, 15-25 parts of long glass fiber, 3-8 parts of metal hydroxide, 0.5-1.5 parts of titanium dioxide, 0.3-0.6 part of an antioxidant, 1-2 parts of nano silicon dioxide, 1-3 parts of zinc molybdate, 2-5 parts of aluminum hypophosphite, 1-2 parts of silicone resin, 0.5-1 part of carbodiimide and 5-8 parts of a toughening agent. The MCA / PA6 flame-retardant composite material disclosed by the invention combines the flame-retardant property of MCA and the excellent physical property of PA6, so that the flame-retardant property of the material is remarkably improved, and meanwhile, the original characteristics of light weight, good toughness, chemical resistance, good durability and the like of PA6 are maintained. By adding the long glass fiber, the metal hydroxide, the titanium dioxide, the antioxidant, the nano silicon dioxide, the zinc molybdate, the aluminum hypophosphite, the silicone resin, the carbodiimide, the flexibilizer and other components, the strength, the heat resistance and the flame retardant effect of the composite material are further enhanced.

Description

Technical Field

[0001] This invention relates to the field of MCA technology, specifically to an MCA / PA6 flame-retardant composite material and its preparation method. Background Technology

[0002] Melamine cyanurate (MCA) is a compound formed by the reaction of melamine and cyanuric acid. This chemical is mainly used in the synthesis of polymer materials, catalysts and other chemical products. In some chemical reactions, MCA can also be used as a nitrogen source to participate in some reactions to form nitrogen-based structures. MCA may be used as an intermediate or additive in the synthesis of some special polymer materials. For example, in some epoxy resins or other high-temperature resistant plastic products, melamine and its derivatives are used as additives to enhance the strength and heat resistance of the materials.

[0003] PA6, also known as Nylon 6, is a translucent or opaque milky-white granule. It possesses thermoplasticity, lightweight, good toughness, chemical resistance, and durability, and is commonly used in automotive parts, mechanical components, electronic and electrical products, and engineering accessories. However, PA6 material itself is flammable, which limits its application in areas requiring high flame retardancy.

[0004] Melamine cyanurate is commonly used as a flame retardant in materials such as plastics, fibers, and rubber. This is because it has high thermal stability and decomposes at high temperatures to produce beneficial chemical substances that inhibit flame spread. It can enhance the high-temperature resistance of materials, reducing their flammability and increasing safety in the event of a fire. As a halogen-free flame retardant, melamine cyanurate contains no halogen components, reducing harmful gas emissions during use. Compared to traditional halogen-containing flame retardants, it has a smaller environmental impact and higher environmental performance.

[0005] To overcome the flammability of PA6 material, this invention proposes an MCA / PA6 flame-retardant composite material, which aims to combine the flame-retardant properties of MCA with the excellent physical properties of PA6 to expand the application range of PA6 material. Summary of the Invention

[0006] The purpose of this invention is to provide an MCA / PA6 flame-retardant composite material and its preparation method, so as to solve the problem of the flammability of PA6 material in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: The first aspect of the present invention provides an MCA / PA6 flame-retardant composite material, comprising the following components and parts by weight: 50-60 parts MCA, 15-20 parts PA6, 15-25 parts long glass fiber, 3-8 parts metal hydroxide, 0.5-1.5 parts titanium dioxide, 0.3-0.6 parts antioxidant, 1-2 parts nano silica, 1-3 parts zinc molybdate, 2-5 parts aluminum hypophosphite, 1-2 parts silicone resin, 0.5-1 part carbodiimide, 5-8 parts toughening agent.

[0008] Preferably, the diameter of the single filament of the long glass fiber is 10-14 μm and the length is 10-20 mm.

[0009] Preferably, the metal hydroxide is one or more of magnesium hydroxide, aluminum hydroxide, and calcium hydroxide.

[0010] Preferably, the antioxidant is one or more selected from phosphites, pentaerythritol esters, and thioesters.

[0011] Preferably, the toughening agent is one or more of POE-g-MAH, EPDM-g-MAH, and PLA-g-MAH.

[0012] Preferably, the MCA / PA6 flame-retardant composite material further includes 0.3-0.7 parts by weight of zinc oxide and 0.15-0.35 parts by weight of zinc borate.

[0013] Preferably, the weight ratio of zinc oxide to zinc borate is 2:1.

[0014] Preferably, the MCA / PA6 flame-retardant composite material further includes 0.5-2 parts by weight of talc and 0.75-3 parts by weight of kaolin.

[0015] Preferably, the long glass fiber is pretreated with silane spray and dried at 100-120°C for 2-3 hours.

[0016] A second aspect of the present invention provides a method for preparing the MCA / PA6 flame-retardant composite material described in the first aspect of the present invention, comprising the following steps: S1. Place PA6 in a vacuum drying oven and dry for 3-5 hours; S2, add MCA into the ball mill, grind, and pass through a 200-mesh sieve; S3, long glass fibers are sprayed with silane and dried at 100-120℃ for 2-3 hours; S4 involves adding each component to a twin-screw extruder for melt blending, extrusion granulation, and injection molding using a screw injection molding machine with a barrel temperature of 230-250℃ and an injection pressure of 80-100MPa.

[0017] The present invention has at least the following beneficial effects: The MCA / PA6 flame-retardant composite material of this invention combines the flame-retardant properties of MCA with the excellent physical properties of PA6. This not only significantly improves the flame-retardant performance of the material but also retains the original lightweight, toughness, chemical resistance, and durability of PA6. By adding various components such as long glass fibers, metal hydroxides, titanium dioxide, antioxidants, nano-silica, zinc molybdate, aluminum hypophosphite, silicone resin, carbodiimide, and toughening agents, the strength, heat resistance, and flame-retardant effect of the composite material are further enhanced, giving it broad market prospects and application value. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0019] This embodiment provides an MCA / PA6 flame-retardant composite material, comprising the following components and parts by weight: 50 parts MCA, 15 parts PA6, 15 parts long glass fiber, 3 parts metal hydroxide, 0.5 parts titanium dioxide, 0.3 parts antioxidant, 1 part nano silica, 1 part zinc molybdate, 2 parts aluminum hypophosphite, 1 part silicone resin, 0.5 parts carbodiimide, and 5 parts toughening agent.

[0020] The long glass fibers have a single filament diameter of 10-14μm and a length of 10-20mm.

[0021] Among them, the metal hydroxide is magnesium hydroxide; the antioxidant is phosphite; and the toughening agent is POE-g-MAH.

[0022] The preparation method of the above MCA / PA6 flame-retardant composite material includes the following steps: S1, Place PA6 in a vacuum drying oven and dry for 3 hours; S2, add MCA into the ball mill, grind, and pass through a 200-mesh sieve; S3, pretreated by silane spraying of long glass fibers, dried at 100℃ for 2 hours; S4 involves adding each component to a twin-screw extruder for melt blending, extrusion granulation, and injection molding using a screw injection molding machine with a barrel temperature of 230℃ and an injection pressure of 80MPa. Example 2

[0023] This embodiment provides an MCA / PA6 flame-retardant composite material, comprising the following components and parts by weight: 55 parts MCA, 18 parts PA6, 20 parts long glass fiber, 5 parts metal hydroxide, 1 part titanium dioxide, 0.5 parts antioxidant, 1.5 parts nano silica, 2 parts zinc molybdate, 3 parts aluminum hypophosphite, 1.5 parts silicone resin, 0.8 parts carbodiimide, and 6 parts toughening agent.

[0024] The long glass fibers have a single filament diameter of 10-14μm and a length of 10-20mm.

[0025] Among them, the metal hydroxide is aluminum hydroxide; the antioxidant is pentaerythritol ester; and the toughening agent is EPDM-g-MAH.

[0026] The preparation method of the above MCA / PA6 flame-retardant composite material includes the following steps: S1, Place PA6 in a vacuum drying oven and dry for 4 hours; S2, add MCA into the ball mill, grind, and pass through a 200-mesh sieve; S3, pretreated by silane spraying of long glass fibers, dried at 110℃ for 2.5h; S4 involves adding each component to a twin-screw extruder for melt blending, extrusion granulation, and injection molding using a screw injection molding machine with a barrel temperature of 240℃ and an injection pressure of 90MPa. Example 3

[0027] This embodiment provides an MCA / PA6 flame-retardant composite material, comprising the following components and parts by weight: 60 parts MCA, 20 parts PA6, 25 parts long glass fiber, 8 parts metal hydroxide, 1.5 parts titanium dioxide, 0.6 parts antioxidant, 2 parts nano silica, 3 parts zinc molybdate, 5 parts aluminum hypophosphite, 2 parts silicone resin, 1 part carbodiimide, and 8 parts toughening agent.

[0028] The long glass fibers have a single filament diameter of 10-14μm and a length of 10-20mm.

[0029] Among them, the metal hydroxide is calcium hydroxide; the antioxidant is thioester; and the toughening agent is PLA-g-MAH.

[0030] The preparation method of the above MCA / PA6 flame-retardant composite material includes the following steps: S1, Place PA6 in a vacuum drying oven and dry for 5 hours; S2, add MCA into the ball mill, grind, and pass through a 200-mesh sieve; S3, pretreated with silane spraying of long glass fibers, dried at 120℃ for 3 hours; S4 involves adding each component to a twin-screw extruder for melt blending, extrusion granulation, and injection molding using a screw injection molding machine with a barrel temperature of 250℃ and an injection pressure of 100MPa. Example 4

[0031] This embodiment provides an MCA / PA6 flame-retardant composite material, which is the same as that in Embodiment 1, except that it also includes 0.3 parts by weight of zinc oxide and 0.15 parts by weight of zinc borate.

[0032] The weight ratio of zinc oxide to zinc borate is 2:1. Example 5

[0033] This embodiment provides an MCA / PA6 flame-retardant composite material, which is the same as Embodiment 2, except that it also includes 0.5 parts by weight of zinc oxide and 0.25 parts by weight of zinc borate.

[0034] The weight ratio of zinc oxide to zinc borate is 2:1. Example 6

[0035] This embodiment provides an MCA / PA6 flame-retardant composite material, which is the same as Embodiment 3, except that it also includes 0.7 parts by weight of zinc oxide and 0.35 parts by weight of zinc borate.

[0036] The weight ratio of zinc oxide to zinc borate is 2:1. Example 7

[0037] This embodiment provides an MCA / PA6 flame-retardant composite material, which is the same as that in Embodiment 1, except that it also includes 0.5 parts by weight of talc powder and 0.75 parts by weight of kaolin. Example 8

[0038] This embodiment provides an MCA / PA6 flame-retardant composite material, which is the same as Embodiment 2, except that it also includes 1 part by weight of talc powder and 2 parts by weight of kaolin. Example 9

[0039] This embodiment provides an MCA / PA6 flame-retardant composite material, which is the same as Embodiment 3, except that it also includes 2 parts by weight of talc powder and 3 parts by weight of kaolin.

[0040] Comparative Example 1 This comparative example provides an MCA / PA6 flame-retardant composite material, comprising the following components and parts by weight: 50 parts MCA, 15 parts PA6, 15 parts long glass fiber.

[0041] The remaining technical features are the same as in Example 1.

[0042] Comparative Example 2 This comparative example provides an MCA / PA6 flame-retardant composite material, comprising the following components and parts by weight: 55 parts MCA, 18 parts PA6, 20 parts long glass fiber, 1 part titanium dioxide, 0.5 parts antioxidant, 1.5 parts nano silica, 1.5 parts silicone resin, 0.8 parts carbodiimide, and 6 parts toughening agent.

[0043] The remaining technical features are the same as in Example 2.

[0044] Comparative Example 3 This comparative example provides an MCA / PA6 flame-retardant composite material, comprising the following components and parts by weight: 60 MCA, 20 PA6.

[0045] The remaining technical features are the same as in Example 3.

[0046] The functions of each component in this invention are as follows: As a flame retardant, MCA can effectively decompose at high temperatures, producing non-flammable gases such as nitrogen and water vapor, which dilutes the concentration of flammable gases. At the same time, the generated char layer can isolate heat transfer and oxygen diffusion, thereby significantly improving the flame retardant performance of the material.

[0047] Long glass fibers can significantly enhance the mechanical properties and thermal stability of composite materials. Their high aspect ratio can effectively hinder crack propagation and improve impact resistance.

[0048] Metal hydroxides, as auxiliary flame retardants, decompose and absorb heat at high temperatures. The resulting water vapor also dilutes flammable gases, further enhancing the flame-retardant effect. Titanium dioxide improves the material's weather resistance and UV stability. Antioxidants effectively prevent thermo-oxidative aging during processing and use, extending the material's service life.

[0049] Nano-silica and zinc molybdate can further improve the flame retardant properties and thermal stability of materials. Nano-silica can also enhance the interfacial bonding force and improve mechanical properties. Aluminum hypophosphite, as an inorganic phosphorus-based flame retardant, can decompose at high temperatures to produce phosphoric acid and other phosphorus-containing compounds, promoting char formation and improving flame retardant efficiency.

[0050] Silicone resin, as a compatibilizer, effectively improves the compatibility between components and enhances the overall performance of the material. Carbodiimide, as a coupling agent, strengthens the interfacial bonding between inorganic fillers and the organic matrix, improving the mechanical properties and thermal stability of the composite material. Toughening agents significantly improve the toughness of the material, enabling its wider application in fields requiring high toughness. The synergistic effect of zinc oxide and zinc borate further improves the flame retardancy and thermal stability of the material while reducing smoke generation. Talc and kaolin further enhance the rigidity and dimensional stability of the material; talc can also act as a nucleating agent.

[0051] The MCA specifications used in Examples 1-9 and Comparative Examples 1-3 are shown in Table 1 below. Table 1 Indicator Name Specific parameters Appearance White or off-white powder Whiteness / % ≥95 purity / % ≥99.5 Residual cyanuric acid / % ≤0.15 Residual melamine / % ≤0.15 Particle size D50 / um 3-5 pH 5-7 Volatile matter / % 0.15 The relevant performance tests were conducted on Examples 1-9 and Comparative Examples 1-3, and the results are shown in Table 2 below: Table 2 Limiting Oxygen Index (LOI) (ASTM D2863) <![CDATA[Smoke density (Ds4) (ASTM E662)]]> Tensile strength (ISO 527) UL94 Vertical Burning (UL94, 0.8mm) Example 1 45.3% 43 101MPa V-0 level Example 2 46.4% 39 104MPa V-0 level Example 3 47.2% 35 109MPa V-0 level Example 4 46.1% 41 103MPa V-0 level Example 5 46.9% 37 105MPa V-0 level Example 6 48.5% 32 111MPa V-0 level Example 7 46.5% 40 104MPa V-0 level Example 8 47.6% 36 107MPa V-0 level Example 9 49.2% 33 112MPa V-0 level Comparative Example 1 28.6% 73 82MPa Level V-1 Comparative Example 2 29.6% 71 87MPa Level V-1 Comparative Example 3 30.4% 68 89MPa Level V-1 in: ① Limiting Oxygen Index: The minimum volume percentage of oxygen required for sustained combustion of a fuel in an oxygen-nitrogen mixture. The calculation formula is as follows:

[0052] ② Smoke density: This is a key parameter for evaluating the smoke generation characteristics of a material during combustion or thermal decomposition, and is tested according to the standard ASTM E662. This test method simulates the smoke concentration produced when a material is exposed to heat radiation or flame in an enclosed space.

[0053] A higher Ds value indicates a higher smoke concentration and a stronger ability to block light. Ds4 represents the specific light density value at 4 minutes.

[0054] ③UL94 Vertical Burning: This test evaluates the flame retardant properties of plastic materials when exposed to a small flame in a vertical direction. The experimental procedures and classification levels are as follows: 1) Sample preparation: Dimensions: 125mm × 13mm × thickness; Quantity: 5 items; Pretreatment: Place at 23℃ / 50% humidity for 48 hours → Aging in a 70℃ oven for 168 hours → Cooling in a dryer for 4 hours.

[0055] 2) Applying flame: Flame height: 20mm; Two ignitions: First time: Flame contacts the lower end of the sample for 10 seconds → record the afterflame time t1; Second time: After the afterflame extinguishes, re-ignite for 10 seconds → Record the afterflame time t2 + afterburn time t3; 3) Observation indicators: Afterflame / afterburn time; Did the burning drippings ignite the absorbent cotton underneath? Whether the flame has spread to the top of the clamp (25mm mark); Was the sample completely burned? 4) The levels are shown in Table 3 below: Table 3 grade Single afterflame Total afterflame time Afterflame + Afterburn dripping ignites Burn until clamps / burn out V-0 level ≤10s ≤50s (sum of 5 items) ≤30s Not allowed Not allowed Level V-1 ≤30s ≤250s ≤60s Not allowed Not allowed As shown in Table 2 above, the MCA / PA6 flame-retardant composite materials prepared in Examples 1-9 exhibit significant improvements in limiting oxygen index, smoke density, tensile strength, and UL94 vertical burning rating compared to Comparative Examples 1-3. The limiting oxygen index of Examples 1-9 is all above 45.3%, significantly higher than the 28.6%-30.4% of Comparative Examples 1-3, indicating that the composite material of the present invention has better flame-retardant properties. Regarding smoke density, the smoke density values ​​of the examples are all between 32-43, significantly lower than the 68-73 of the comparative examples, indicating less smoke produced during combustion, which is beneficial for escape and rescue at fire scenes. Regarding tensile strength, the tensile strength of Examples 1-9 is all above 101 MPa, higher than the 82-89 MPa of Comparative Examples 1-3, demonstrating that the composite material maintains excellent mechanical properties while retaining flame-retardant properties. Regarding the UL94 vertical flammability rating, Examples 1-9 all achieved a V-0 rating, while Comparative Examples 1-3 only achieved a V-1 rating, further demonstrating the superior flame-retardant properties of the composite material of the present invention.

[0056] In summary, the MCA / PA6 flame-retardant composite material of this invention effectively overcomes the flammability defect of PA6 material, significantly improves the flame-retardant and mechanical properties of the composite material, expands the application range of PA6 material, and has broad application prospects and significant socio-economic benefits. A series of rigorous performance tests have verified its reliability and superiority in practical applications. Compared with traditional flame-retardant materials, the composite material of this invention shows significant improvements in limiting oxygen index, smoke density, tensile strength, and UL94 vertical flammability rating. In particular, it has achieved a major breakthrough in flame-retardant and mechanical properties, and is expected to be widely used in fields with high requirements for flame-retardant and mechanical properties, such as automotive parts, electronic and electrical products, and engineering components, providing safer and more reliable protection for people's lives and work.

[0057] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or basic characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0058] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An MCA / PA6 flame-retardant composite material, characterized in that, Includes the following components and parts by weight: 50-60 parts MCA, 15-20 parts PA6, 15-25 parts long glass fiber, 3-8 parts metal hydroxide, 0.5-1.5 parts titanium dioxide, 0.3-0.6 parts antioxidant, 1-2 parts nano silica, 1-3 parts zinc molybdate, 2-5 parts aluminum hypophosphite, 1-2 parts silicone resin, 0.5-1 part carbodiimide, 5-8 parts toughening agent.

2. The MCA / PA6 flame-retardant composite material according to claim 1, characterized in that: The long glass fiber has a single filament diameter of 10-14 μm and a length of 10-20 mm.

3. The MCA / PA6 flame-retardant composite material according to claim 1, characterized in that: The metal hydroxide is one or more of magnesium hydroxide, aluminum hydroxide, and calcium hydroxide.

4. The MCA / PA6 flame-retardant composite material according to claim 1, characterized in that: The antioxidant is one or more of phosphites, pentaerythritol esters, and thioesters.

5. The MCA / PA6 flame-retardant composite material according to claim 1, characterized in that: The toughening agent is one or more of POE-g-MAH, EPDM-g-MAH, and PLA-g-MAH.

6. The MCA / PA6 flame-retardant composite material according to claim 1, characterized in that: The MCA / PA6 flame-retardant composite material also includes 0.3-0.7 parts by weight of zinc oxide and 0.15-0.35 parts by weight of zinc borate.

7. The MCA / PA6 flame-retardant composite material according to claim 6, characterized in that: The weight ratio of zinc oxide to zinc borate is 2:

1.

8. The MCA / PA6 flame-retardant composite material according to claim 1, characterized in that: The MCA / PA6 flame-retardant composite material also includes 0.5-2 parts by weight of talc and 0.75-3 parts by weight of kaolin.

9. The MCA / PA6 flame-retardant composite material according to claim 8, characterized in that: The long glass fibers are pretreated with silane spray and dried at 100-120℃ for 2-3 hours.

10. The method for preparing the MCA / PA6 flame-retardant composite material according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Place PA6 in a vacuum drying oven and dry for 3-5 hours; S2, add MCA into the ball mill, grind, and pass through a 200-mesh sieve; S3, long glass fibers are sprayed with silane and dried at 100-120℃ for 2-3 hours; S4 involves adding each component to a twin-screw extruder for melt blending, extrusion granulation, and injection molding using a screw injection molding machine with a barrel temperature of 230-250℃ and an injection pressure of 80-100MPa.

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