A halogen-free flame-retardant nylon material and its preparation method

Abstract

This invention discloses a highly efficient synergistic halogen-free flame-retardant nylon material and its preparation method. Specifically, it is prepared from 57-60 parts by weight of nylon resin, 30 parts by weight of short glass fibers, 10-13 parts by weight of halogen-free flame retardant, 1-3 parts by weight of wollastonite mineral fibers, 0.2-0.5 parts by weight of antioxidant, 0.2-0.5 parts by weight of lubricant, and 0.2-0.4 parts by weight of coupling agent. The material prepared by this invention, through the addition of wollastonite mineral fibers, forms a synergistic flame-retardant effect with the halogen-free flame retardant, which not only improves the flame-retardant performance of the material but also improves its flowability and dimensional stability, reduces the exposure of glass fibers, and enhances the mechanical properties of the material. Furthermore, wollastonite mineral fibers are inexpensive, which can reduce the cost of composite materials, making it very suitable for halogen-free flame-retardant nylon materials and enabling large-scale promotion and use.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a halogen-free flame-retardant nylon material and its preparation method. Background Technology

[0002] Nylon possesses high mechanical strength, heat resistance, low coefficient of friction, wear resistance, self-lubrication, oil resistance, and good electrical insulation, and is mainly used in engineering plastics and synthetic fibers. Nylon 6 (PA6) is the most commonly used in engineering plastics and has been widely applied in electronics, electrical appliances, and construction engineering. However, PA6 itself is flammable, and these applications require excellent flame-retardant properties, making flame-retardant modification necessary.

[0003] Due to the poor dimensional stability and processing performance of PA6, inorganic fillers are generally used in practical applications to improve its dimensional stability and processing performance, and to some extent reduce costs. Commonly used flame retardants in existing technologies include halogenated flame retardants, phosphorus-based flame retardants, phosphorus-nitrogen compound flame retardants, and inorganic flame retardants. Among these, halogenated flame retardants are restricted in their use because they produce large amounts of smoke and corrosive gases during combustion.

[0004] Phosphorus-based flame retardants are characterized by low toxicity, low smoke, halogen-free properties, and high flame retardancy. Their flame retardant mechanism mainly involves forming a stable carbon layer to achieve heat insulation, oxygen barrier, and improved flame retardant performance. However, the addition of these flame retardants to nylon materials often results in a large proportion, significantly reducing the material's mechanical properties. Therefore, it is necessary to develop a highly efficient, synergistic, halogen-free flame-retardant nylon material. Summary of the Invention

[0005] In view of the above, the present invention provides a halogen-free flame-retardant nylon material and its preparation method to solve the problems mentioned in the background art. The nylon material has good flame retardant effect, meets environmental protection requirements, and can improve the material's fluidity and dimensional stability, enhance the material's mechanical properties, and reduce the material's cost.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention discloses a high-efficiency synergistic halogen-free flame-retardant nylon material, which is prepared by weight proportions of 57-60 parts nylon resin, 30 parts short glass fiber, 10-13 parts halogen-free flame retardant, 1-3 parts wollastonite mineral fiber, 0.2-0.5 parts antioxidant, 0.2-0.5 parts lubricant, and 0.2-0.4 parts coupling agent.

[0008] In a further embodiment, it can be understood that the nylon resin is one or more of the commonly used nylon 6 resin or nylon 66 resin.

[0009] In a further embodiment, the short glass fiber has a diameter of 8-12 μm and a length of 1-5 mm. Preferably, it has a diameter of 10 μm and a length of 3 mm.

[0010] In a further embodiment, the halogen-free flame retardant is a phosphorus-based flame retardant, specifically a high-concentration red phosphorus flame retardant masterbatch or a hypophosphite flame retardant masterbatch, with nylon 6 resin as the carrier. In a specific embodiment of the present invention, red phosphorus flame retardant masterbatch is preferred.

[0011] In a further embodiment, the main components of the wollastonite mineral fiber are SiO2 and CaO, with a whiteness ≥88, a diameter of 15-20μm, and an aspect ratio of 8:1-10:1. In a specific embodiment, a small amount of fiber with a highly efficient flame-retardant synergistic effect is added.

[0012] In a further embodiment, the antioxidant is a compound of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and tris(2,4-di-tert-butylphenyl)phosphite.

[0013] In a further embodiment, the lubricant is a blend of ethylene bis-stearamide and ethylene acrylic acid copolymer in a 1:1 ratio.

[0014] In a further embodiment, the coupling agent is selected as γ-aminopropyltriethoxysilane (KH550), whose main function is to increase the wettability and dispersibility of wollastonite mineral fibers in the polymer.

[0015] In another aspect, this invention discloses a method for preparing a halogen-free flame-retardant nylon material as described in any of the preceding claims, comprising the following steps:

[0016] The nylon resin, halogen-free flame retardant, wollastonite mineral fiber, antioxidant, lubricant, and coupling agent are thoroughly mixed according to the formula to obtain a homogeneous mixture.

[0017] The mixture is added to a twin-screw extruder, and short glass fibers are simultaneously added from the middle section of the twin-screw extruder. After melting, extrusion, granulation, and drying, a halogen-free flame-retardant nylon material is obtained. It is understood that the processing temperature and speed of the twin-screw extruder can be adjusted according to the specific type of raw material, and therefore there are no particular limitations. In some specific embodiments of the present invention, the processing temperatures of each zone of the twin-screw extruder are sequentially: Zone 1 180-190℃, Zone 2 190-200℃, Zone 3 210-220℃, Zone 4 220-230℃, Zone 5 220-230℃, Zone 6 220-230℃, Zone 7 220-230℃, Zone 8 220-230℃, and Die Zone 220-230℃; the screw speed is 150-300 r / min.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] In this invention, wollastonite mineral fibers are added to form a synergistic flame retardant with phosphorus-based flame retardants. Compared with existing synergistic flame retardants such as zinc phosphate-borate and zinc oxide, the addition of wollastonite mineral fibers results in a smaller amount of flame retardant and a better flame retardant effect. The main mechanism is that silicon can catalyze the formation of a char layer, making the surface of the char layer dense and smooth. This effectively isolates the heat and flammable gases generated by the substances in the char layer from spreading to the outside of the char layer, enabling the material to achieve self-extinguishing and improving the flame retardant performance of the material.

[0020] Furthermore, the addition of silane coupling agents allows wollastonite mineral fibers to disperse well in the matrix resin, increasing the interfacial bonding between wollastonite and the resin, further improving the flame retardancy of the material. It also enhances the flowability, dimensional stability, and mechanical properties of the composite material, mitigating fiber floating. On the other hand, wollastonite mineral fibers are significantly cheaper than zinc borate and zinc oxide, reducing the cost of the composite material. Moreover, the preparation process is simple, making it well-suited for applications in flame-retardant materials for electronics, appliances, and tools, and highly suitable for commercialization. Detailed Implementation

[0021] To facilitate understanding of the present invention, a more comprehensive description will be given below with reference to specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0023] The specific information of the raw materials used in the following examples and comparative examples is as follows:

[0024] Nylon 6: PA6-BE3250, Jiangsu Hongsheng New Material Co., Ltd.;

[0025] Short fiberglass: ECS10-03-568H; Jushi;

[0026] Halogen-free flame retardant: Flame retardant-MPA2340T; Wuhu Ruiao New Materials;

[0027] Wollastonite mineral fiber: AH-BAKF, aspect ratio 8:1-10:1, Jiangxi Aote Technology;

[0028] Antioxidant: A mixture of antioxidant 1010 and antioxidant 168 in a 1:1 mass ratio;

[0029] Lubricant: A mixture of lubricant EBS and lubricant A-C540A in a 1:1 mass ratio;

[0030] Coupling agent: Coupling agent-KH550, Hefei Yuchuang Innovation Materials Technology Co., Ltd.

[0031] It is understood that the above-mentioned raw materials and reagents are merely examples of some specific embodiments of the present invention, making the technical solution of the present invention clearer, and do not mean that the present invention can only use the above-mentioned reagents. The specific scope shall be determined by the claims. In addition, unless otherwise specified, "parts" in the examples and comparative examples refer to parts by weight.

[0032] Any range described in this invention includes the endpoint, any value between the endpoints, and any subrange consisting of the endpoint or any value between the endpoints.

[0033] Example 1

[0034] 59 parts of nylon 6 resin, 10 parts of flame retardant, 1 part of wollastonite mineral fiber, 0.3 parts of coupling agent, 0.4 parts of antioxidant, and 0.6 parts of lubricant were mixed evenly and then added to a twin-screw extruder. Simultaneously, 30 parts of short glass fiber were added from the middle section of the twin-screw extruder. The mixture was then melted, extruded, granulated, and dried to obtain a halogen-free flame-retardant nylon material. The extrusion temperatures in each zone of the twin-screw extruder were: Zone 1 180℃, Zone 2 200℃, Zone 3 220℃, Zone 4 230℃, Zone 5 230℃, Zone 6 230℃, Zone 7 230℃, Zone 8 230℃, and Die Zone 225℃; the screw speed was 300 r / min.

[0035] Example 2

[0036] 58 parts of nylon 6 resin, 10 parts of flame retardant, 2 parts of wollastonite mineral fiber, 0.3 parts of coupling agent, 0.4 parts of antioxidant, and 0.6 parts of lubricant were mixed evenly and then added to a twin-screw extruder. Simultaneously, 30 parts of short glass fiber were added from the middle section of the twin-screw extruder. The mixture was then melted, extruded, granulated, and dried to obtain a halogen-free flame-retardant nylon material. The extrusion temperatures in each zone of the twin-screw extruder were: Zone 1 180℃, Zone 2 200℃, Zone 3 220℃, Zone 4 230℃, Zone 5 230℃, Zone 6 230℃, Zone 7 230℃, Zone 8 230℃, and the die zone 225℃. The screw speed was 300 r / min.

[0037] Example 3

[0038] 57 parts of nylon 6 resin, 10 parts of flame retardant, 3 parts of wollastonite mineral fiber, 0.3 parts of coupling agent, 0.4 parts of antioxidant, and 0.6 parts of lubricant were mixed evenly and then added to a twin-screw extruder. Simultaneously, 30 parts of short glass fiber were added from the middle section of the twin-screw extruder. The mixture was then melted, extruded, granulated, and dried to obtain a halogen-free flame-retardant nylon material. The extrusion temperatures in each zone of the twin-screw extruder were: Zone 1 180℃, Zone 2 200℃, Zone 3 220℃, Zone 4 230℃, Zone 5 230℃, Zone 6 230℃, Zone 7 230℃, Zone 8 230℃, and the die zone 225℃. The screw speed was 300 r / min.

[0039] Comparative Example 1

[0040] 59 parts of nylon 6 resin, 10 parts of flame retardant, 1 part of wollastonite mineral fiber, 0.4 parts of antioxidant, and 0.6 parts of lubricant were mixed evenly and then added to a twin-screw extruder. Simultaneously, 30 parts of short glass fiber were added from the middle section of the twin-screw extruder. The mixture was then melted, extruded, granulated, and dried to obtain a halogen-free flame-retardant nylon material. The extrusion temperatures in each zone of the twin-screw extruder were: Zone 1 180℃, Zone 2 200℃, Zone 3 220℃, Zone 4 230℃, Zone 5 230℃, Zone 6 230℃, Zone 7 230℃, Zone 8 230℃, and Die Zone 225℃; the screw speed was 300 r / min.

[0041] Comparative Example 2

[0042] 58 parts by weight of nylon 6 resin, 10 parts by weight of flame retardant, 2 parts by weight of wollastonite mineral fiber, 0.4 parts by weight of antioxidant, and 0.6 parts by weight of lubricant were mixed evenly and then added to a twin-screw extruder. Simultaneously, 30 parts by weight of short glass fiber were added from the middle section of the twin-screw extruder. The mixture was then melted, extruded, granulated, and dried to obtain a halogen-free flame-retardant nylon material. The extrusion temperatures in each zone of the twin-screw extruder were: Zone 1 180℃, Zone 2 200℃, Zone 3 220℃, Zone 4 230℃, Zone 5 230℃, Zone 6 230℃, Zone 7 230℃, Zone 8 230℃, and Die Zone 225℃. The screw speed was 300 r / min.

[0043] Comparative Example 3

[0044] 57 parts of nylon 6 resin, 10 parts of flame retardant, 3 parts of wollastonite mineral fiber, 0.4 parts of antioxidant, and 0.6 parts of lubricant were mixed evenly and then added to a twin-screw extruder. Simultaneously, 30 parts of short glass fiber were added from the middle section of the twin-screw extruder. The mixture was then melted, extruded, granulated, and dried to obtain a halogen-free flame-retardant nylon material. The extrusion temperatures in each zone of the twin-screw extruder were: Zone 1 180℃, Zone 2 200℃, Zone 3 220℃, Zone 4 230℃, Zone 5 230℃, Zone 6 230℃, Zone 7 230℃, Zone 8 230℃, and Die Zone 225℃; the screw speed was 300 r / min.

[0045] Comparative Example 4

[0046] 60 parts of nylon 6 resin, 10 parts of flame retardant, 0.4 parts of antioxidant, and 0.6 parts of lubricant were mixed evenly and then added to a twin-screw extruder. Simultaneously, 30 parts of short glass fiber were added from the middle section of the twin-screw extruder. The mixture was then melted, extruded, granulated, and dried to obtain a composite nylon material. The extrusion temperatures in each zone of the twin-screw extruder were: Zone 1 180℃, Zone 2 200℃, Zone 3 220℃, Zone 4 230℃, Zone 5 230℃, Zone 6 230℃, Zone 7 230℃, Zone 8 230℃, and Die Zone 225℃. The screw speed was 300 r / min.

[0047] Comparative Example 5

[0048] 57 parts of nylon 6 resin, 13 parts of flame retardant, 0.4 parts of antioxidant, and 0.6 parts of lubricant were mixed evenly and then added to a twin-screw extruder. Simultaneously, 30 parts of short glass fiber were added from the middle section of the twin-screw extruder. The mixture was then melted, extruded, granulated, and dried to obtain a composite nylon material. The extrusion temperatures in each zone of the twin-screw extruder were: Zone 1 180℃, Zone 2 200℃, Zone 3 220℃, Zone 4 230℃, Zone 5 230℃, Zone 6 230℃, Zone 7 230℃, Zone 8 230℃, and Die Zone 225℃. The screw speed was 300 r / min.

[0049] Test case

[0050] The halogen-free flame-retardant nylon materials prepared in Examples 1-6 and Comparative Examples 1-2 were injection molded into specimens according to national standards. After conditioning at 23°C and 50% humidity, the mechanical properties of the composite materials were tested according to GB / T 1040, GB / T 9341, and GB / T 1043, respectively, and the combustion performance was tested according to UL94 standard. The results are shown in Table 1.

[0051] Table 1

[0052]

[0053] Note: The dimensions or conditions of each performance test strip in Table 1 are as follows:

[0054] The test conditions for the notched impact strength of a simply supported beam are as follows: the spline is rectangular (V-shaped molded notch), and the spline size is 80mm×10mm×4mm;

[0055] The tensile strength test conditions are as follows: the test speed is 5 mm / min, the specimen is dumbbell-shaped, and the specimen size is 170 mm × 10 mm × 4 mm.

[0056] The bending strength test conditions are as follows: the test speed is 2 mm / min, the spline is rectangular, and the spline size is 80 mm × 10 mm × 4 mm.

[0057] The dimensions of the flame-retardant test strip are as follows: the test strip is rectangular, and the dimensions are 125mm × 12.75mm × 2.0mm;

[0058] The test results in Table 1 show that adding different amounts of wollastonite mineral fibers can improve the flame retardant rating of the composite material, reduce the proportion of flame retardant added, and create a synergistic flame retardant effect with phosphorus-based flame retardants. Furthermore, Examples 1-3 and Comparative Examples 1-3 demonstrate that the addition of coupling agents to wollastonite mineral fibers not only improves the flame retardant properties of the material but also enhances its mechanical properties. This is primarily because the addition of coupling agents allows the wollastonite mineral fibers to disperse well in the resin, increasing their interfacial bonding ability. On the other hand, wollastonite mineral fibers are inexpensive compared to other synergistic flame retardants (zinc borate, zinc oxide), reducing the cost of the composite material. They also improve the material's flowability and reduce fiber floating, and the preparation process is simple, making them well-suited for applications in flame-retardant materials for electronics, electrical appliances, and tools.

[0059] Although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0060] Therefore, the above description is only a preferred embodiment of this application and is not intended to limit the scope of this application; that is, all equivalent modifications made in accordance with the scope of the claims of this application shall be within the protection scope of the claims of this application.

Claims

1. A halogen-free flame-retardant nylon material, characterized in that, It is prepared from the following components in parts by weight: 57-60 parts of nylon resin 30 parts short glass fiber 10 parts of halogen-free flame retardant 1-3 parts of wollastonite mineral fiber Antioxidant 0.2-0.6 parts, Lubricant 0.2-0.6 parts, 0.2-0.4 parts of coupling agent; The halogen-free flame retardant is red phosphorus flame retardant masterbatch or hypophosphite flame retardant masterbatch. The wollastonite mineral fibers have a whiteness ≥88, a diameter of 15-20μm, and an aspect ratio of 8:1-10:

1. The coupling agent is γ-aminopropyltriethoxysilane.

2. The halogen-free flame-retardant nylon material according to claim 1, characterized in that, The nylon resin is at least one of nylon 6 or nylon 66.

3. The halogen-free flame-retardant nylon material according to claim 1, characterized in that, The short glass fibers have a diameter of 8-12 μm and a length of 1-5 mm.

4. The halogen-free flame-retardant nylon material according to claim 1, characterized in that, The antioxidant is a compound of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and tris(2,4-di-tert-butylphenyl)phosphite].

5. The halogen-free flame-retardant nylon material according to claim 1, characterized in that, The lubricant is at least one of ethylene bis-stearamide and ethylene acrylic acid copolymer.

6. A method for preparing a halogen-free flame-retardant nylon material according to any one of claims 1-5, characterized in that, Includes the following steps: The nylon resin, halogen-free flame retardant, wollastonite mineral fiber, antioxidant, lubricant and coupling agent are thoroughly mixed according to the weight parts to obtain a mixture. The mixture is added to the main feed port of a twin-screw extruder, and short glass fibers are added to the side feed port of the twin-screw extruder. After melting, extrusion, granulation and drying, halogen-free flame-retardant nylon material is obtained. The processing temperatures of each zone of the twin-screw extruder are as follows: Zone 1 180-190℃, Zone 2 190-200℃, Zone 3 210-220℃, Zone 4 220-230℃, Zone 5 220-230℃, Zone 6 220-230℃, Zone 7 220-230℃, Zone 8 220-230℃, and Die Zone 220-230℃; the screw speed is 150-300 r / min.

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