Flame-retardant nylon cable sheath material and preparation method thereof

Abstract

The present application relates to the field of nylon technology, and specifically to a flame-retardant nylon cable sheath material and its preparation method. The flame-retardant nylon cable sheath material of the present application comprises the following components by weight: 55-95 parts of PA6, 4.5-7.7 parts of a melamine-carboxylated silica-modified chitosan composite, 0.3-0.6 parts of a cross-linking agent, 0.3-0.6 parts of a lubricant, and 1-1.8 parts of an antioxidant. The flame-retardant nylon cable sheath material uses a composite of melamine, silica, and chitosan as a flame retardant, and is cross-linked and modified with a cross-linking agent. The resulting flame-retardant nylon cable sheath material not only has excellent high-temperature resistance and flame retardancy, but also has high mechanical properties.

Description

Technical Field

[0001] The present application relates to the field of nylon technology, and more specifically, to a flame-retardant nylon cable sheath material and a preparation method thereof. Background Art

[0002] Polyamide (PA), commonly known as nylon, is the largest, most diverse, and most widely used of the five major engineering plastics. In the field of communication optical cables, nylon 6 has outstanding weather resistance, good low-temperature resistance, dimensional stability, and is resistant to termites and rodents. It is an excellent material for cable sheathing and is widely used in the sheathing of optical fiber communication cables and large-size power cables.

[0003] Thermoplastics, which melt and plasticize at a certain temperature, facilitate molding into various structural components. This is a significant advantage of plastics over thermosets. However, polyamide products cannot compete with thermosets in terms of transient high-temperature resistance, limiting their application. This is particularly true in electrical components. If a cable short circuits or is exposed to open flames, the cable will experience localized, transient high temperatures, causing the PA material to melt instantly, leading to component failure and accidents. Summary of the Invention

[0004] In order to solve the above problems, the present application provides a flame-retardant nylon cable sheath material and a preparation method thereof, which uses a material composed of melamine, silica and chitosan as a flame retardant, and uses a cross-linking agent to cross-link and modify the nylon. The flame-retardant nylon cable sheath material obtained in this way not only has excellent high temperature resistance and flame retardant properties, but also has high mechanical properties.

[0005] In a first aspect, the present application provides a flame-retardant nylon cable sheath material, comprising the following components in parts by weight: 95 parts of PA655, 4.5-7.7 parts of melamine-carboxylated silica modified chitosan composite, 0.3-0.6 parts of cross-linking agent, 0.3-0.6 parts of lubricant, and 1-1.8 parts of antioxidant.

[0006] This application uses PA6 as a base material and adds a set amount of melamine-carboxylated silica-modified chitosan composite. Melamine can delay ignition by endothermic dissociation in the early stages of combustion. The nitrogen generated by its combustion can also act as an inert diluent, reducing the intensity of the flame. In addition, it can also produce a char layer during the combustion process to isolate air and combustible materials. During the combustion process, silica forms a dense and stable silicon-containing carbon layer. This carbon layer not only prevents the escape of combustible materials during combustion and decomposition, but also acts as a heat and oxygen barrier, thereby preventing the thermal decomposition of the polymer material and achieving flame retardancy and low smoke effects. Chitosan is a linear polysaccharide composed of multiple glucosamine molecules connected by β-1,4-glycosidic bonds. This structure enables chitosan to form a stable carbon layer at high temperatures, thereby providing heat and oxygen insulation, effectively preventing the spread of flames. In addition, carboxylated silica-modified chitosan can also adsorb metal elements such as nickel, lead, and cadmium that may be precipitated during cable combustion, significantly reducing the impact of cable combustion on the environment.

[0007] This application combines melamine, silica, and chitosan into one, allowing the three to complement each other and effectively improve the flame retardant properties of the flame-retardant nylon cable sheath material. It is also environmentally friendly. The composite material can also improve the stability of chitosan during the material preparation process and the dispersion effect of silica in the system. Compared with the method of adding the three separately, the above-mentioned composite material can reduce the degree of instantaneous melting of the PA material caused by local instantaneous high heat, thereby effectively improving the high-temperature resistance of the flame-retardant nylon cable sheath material.

[0008] On this basis, a set amount of cross-linking agent is added in this application. The cross-linking agent is used to cross-link and modify PA6, improving the overall performance of PA6. On the other hand, it can also bond and stabilize the melamine-carboxylated silica-modified chitosan composite dispersed in PA6, enabling the composite to function effectively and further improving the high temperature resistance and mechanical properties of the flame-retardant nylon cable sheath material.

[0009] Preferably, the preparation method of the melamine-carboxylated silica modified chitosan composite comprises the following steps: taking melamine and dispersing it evenly with methanol, then adding carboxylated silica modified chitosan to react, and filtering and drying to obtain the composite.

[0010] Adopting the above technical solution, the present application uses methanol as a medium to facilitate subsequent volatilization, recovery and reuse. The -COOH in the carboxylated silica is acidic and can react with the -NH2 in melamine to form an amide bond (-CONH-), thereby compounding melamine with the carboxylated silica-modified chitosan. The obtained composite material has a multi-layer network structure, which is beneficial to increase the specific surface area to reduce the probability of its precipitation from PA6. The above preparation process is simple to operate and highly operable.

[0011] Preferably, the weight ratio of the melamine to the carboxylated silica modified chitosan composite is 9:1.

[0012] Using the above technical solution, the present applicant has found through experimental research that the melamine-carboxylated silica modified chitosan composite prepared according to the above weight ratio has more excellent high temperature resistance, flame retardancy and mechanical properties, and therefore it is further preferred.

[0013] Preferably, the preparation method of the carboxylated silica-modified chitosan comprises the following steps: dispersing silica in an ether solution, slowly adding succinate, filtering and drying after the reaction is completed to obtain carboxylated silica; dispersing chitosan in n-butanol, slowly adding carboxylated silica, filtering and drying after the reaction is completed to obtain the carboxylated silica-modified chitosan.

[0014] Preferably, the weight ratio of the carboxylated silica to the chitosan is 1.2:1.

[0015] Using the above technical solution, this application uses ether and succinate to first carboxylate silica, and then uses n-butanol to modify chitosan. The reaction process is controllable and can produce carboxylated silica-modified chitosan with a higher yield. Conventionally, six parts silica are used to one part chitosan. In this application, a moderate excess of carboxylated silica is used to effectively ensure that the chitosan is fully modified, avoiding the appearance of free chitosan that affects the flame-retardant nylon cable sheath material. The excess carboxylated silica can also be combined with melamine as a flame retardant, ensuring the excellent flame retardant properties of the flame-retardant nylon cable sheath material.

[0016] Preferably, the cross-linking agent is selected from one or more of triallyl cyanurate, triallyl isocyanurate, trimethylallyl isocyanurate, and trimethylolpropane trimethacrylate.

[0017] Preferably, the cross-linking agent is a mixture of triallyl isocyanurate and trimethylallyl isocyanurate in a weight ratio of 3:1.

[0018] Using the above technical solution, triallyl cyanurate (TAC), triallyl isocyanurate (TAIC), trimethylallyl isocyanurate (TMAIC), and trimethylolpropane trimethacrylate (TMPTMA), all common crosslinking agents for nylon, all exhibited excellent crosslinking effects in this application to produce a flame-retardant nylon cable sheath material with excellent performance. Specifically, when the crosslinking agent is a mixture of triallyl isocyanurate and trimethylallyl isocyanurate in a weight ratio of 3:1, the resulting flame-retardant nylon cable sheath material exhibits significantly superior performance compared to the other crosslinking agents, and therefore is further preferred.

[0019] Preferably, the lubricant is selected from one or more of silicone, stearic acid, stearate, pentaerythritol stearate, organosiloxane, polyester wax, mesoamide, and alkane wax.

[0020] Preferably, the antioxidant is selected from one or more of hindered phenols and phosphite antioxidants.

[0021] In a second aspect, the present application provides a method for preparing a flame-retardant nylon cable sheath material, comprising the following steps:

[0022] A set amount of PA6, melamine-carboxylated silica modified chitosan composite, crosslinking agent and lubricant are placed in a vacuum reactor and fully stirred and mixed at a temperature of 150-160°C. The obtained mixture is cooled to room temperature and then flattened and irradiated. After the irradiation is completed, a set amount of antioxidant is added and mixed evenly. Finally, granulation is carried out through a twin-screw extruder at an extrusion temperature of 250-280°C to obtain the flame-retardant nylon cable sheath material.

[0023] In the present application, PA6 is mixed with a melamine-carboxylated silica modified chitosan composite, a crosslinker and a lubricant and then directly subjected to irradiation crosslinking, thereby reducing the difficulty of dispersing the nylon with the melamine-carboxylated silica modified chitosan composite after cross-linking. In addition, the stability of the system of nylon and the composite after dispersion can be further increased, thereby obtaining a flame-retardant nylon cable sheath material with better high temperature resistance and mechanical properties.

[0024] In summary, this application has the following beneficial effects:

[0025] 1. This application uses a composite material of melamine, silicon dioxide and chitosan as a flame retardant, and uses a cross-linking agent to cross-link and modify nylon. The flame-retardant nylon cable sheath material obtained thereby not only has excellent high temperature resistance and flame retardancy, but also has high mechanical properties;

[0026] 2. This application further improves the high temperature resistance, flame retardancy and mechanical properties of the flame retardant nylon cable sheath material by strictly controlling the components and dosage.

[0027] 3. The preparation method of the present application further increases the stability of the system of nylon and the composite material after dispersion by pre-mixing the raw materials and irradiating and cross-linking, thereby obtaining a flame-retardant nylon cable sheath material with better high temperature resistance and mechanical properties. DETAILED DESCRIPTION

[0028] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0029] The raw materials and reagents used in this application are all purchased from commercial products. The key parameters of the main raw materials are as follows:

[0030] PA6, using German BASF B3S low-viscosity pure resin, flame retardant performance HB;

[0031] Melamine, analytical grade with an active ingredient content of 99%, was purchased from Henan Xinzhiyuan Chemical Products Co., Ltd.

[0032] Silica, using dispersible nano-silica particles, was purchased from Henan Nanotechnology Co., Ltd.;

[0033] Chitosan (CTS), with a deacetylation degree of 96%, was purchased from Shaanxi Changji Fu Biotechnology Co., Ltd.

[0034] Diethyl ether, succinic anhydride, n-butanol, and methanol were all analytical grade;

[0035] A cross-linking agent selected from one or more of triallyl cyanurate (TAC), triallyl isocyanurate (TAIC), trimethylallyl isocyanurate (TMAIC), and trimethylolpropane trimethacrylate (TMPTMA), preferably a cross-linking agent prepared by mixing triallyl isocyanurate (TAIC) and trimethylallyl isocyanurate (TMAIC) in a weight ratio of 3:1;

[0036] Lubricant, selected from one or more of silicone, stearic acid, stearate, pentaerythritol stearate, organosiloxane, polyester wax, acid amide, and alkane wax. This application specifically uses stearic acid model SA1801 as an example for description;

[0037] The antioxidant is selected from one or more of hindered phenols and phosphite antioxidants. This application specifically describes a mixture of antioxidant 1098 and antioxidant 168 from Tianjin RIANOX in a weight ratio of 1:1 as an example.

[0038] The present application is further described in detail below with reference to the following examples and comparative examples. Example Example 1

[0039] This embodiment provides a method for preparing a flame-retardant nylon cable sheath material, comprising the following steps:

[0040] (1) Preparation of carboxylated silica-modified chitosan

[0041] Take 75g of silica and disperse it in 5L of ether solution, slowly add 50g of succinate glycoside, and react at a constant temperature of 20°C for 2h. After the reaction is completed, filter to obtain a solid powdery substance, place it in a constant temperature box at 40°C and vacuum dry it for 4h to obtain carboxylated silica; take 10g of chitosan and disperse it in 2L of n-butanol and stir it for 0.5h, slowly add 12g of the above-mentioned carboxylated silica, stir and heat to 65°C and react at a constant temperature for 7h, cool to room temperature, use a vacuum pump to filter to obtain a solid powdery substance, place it in a constant temperature box at 70°C and vacuum dry it for 6h to obtain carboxylated silica modified chitosan.

[0042] (2) Preparation of melamine-carboxylated silica modified chitosan composite

[0043] Take 90g of melamine and disperse it evenly with 1L of methanol, then add 10g of carboxylated silica modified chitosan, and stir the reaction at a constant temperature of 20°C until a white precipitate gradually precipitates in the system. Continue stirring the reaction for 1h and then stop. After standing for 1h, filter it and wash the sample with methanol 3 times and then dry it to obtain a melamine-carboxylated silica modified chitosan composite.

[0044] (3) Preparation of flame-retardant nylon cable sheath materials

[0045] 800g of PA6, 65g of melamine-carboxylated silica modified chitosan composite, 5g of crosslinking agent and 5g of lubricant are placed in a vacuum reactor, wherein the crosslinking agent is prepared by mixing triallyl isocyanurate TAIC and trimethylallyl isocyanurate TMAIC in a weight ratio of 3:1, and the mixture is fully stirred and mixed at a temperature of 155°C. The obtained mixture is cooled to room temperature, then flattened and irradiated. The irradiation processing conditions are electron beam, and the irradiation dose is 100kGy. After the irradiation is completed, 15g of antioxidant is added and mixed evenly. Finally, granulation is carried out through a twin-screw extruder. The screw length-diameter ratio of the twin-screw extruder is 40:1, the screw speed is 350rpm, and the extrusion temperature is 270°C to obtain a flame-retardant nylon cable sheath material.

[0046] The flame-retardant nylon cable sheath material obtained was put into an injection molding machine for extrusion. The extrusion temperature was 240° C., and the thickness of the extruded cable sheath was 1.5±0.01 mm. The flame-retardant nylon cable sheath was obtained as a test sample. Example 2

[0047] In this embodiment, based on the method of Example 1, the component dosage and process parameters for preparing the flame-retardant nylon cable sheath material are adjusted as follows:

[0048] 550 g of PA6, 45 g of melamine-carboxylated silica modified chitosan composite, 3 g of a cross-linking agent and 3 g of a lubricant were placed in a vacuum reactor, wherein the cross-linking agent was prepared by mixing triallyl isocyanurate TAIC and trimethylallyl isocyanurate TMAIC in a weight ratio of 3:1, and the mixture was fully stirred and mixed at a temperature of 150 ° C. The obtained mixture was cooled to room temperature, then flattened and irradiated. The irradiation processing conditions were electron beam, and the irradiation dose was 100 kGy. After the irradiation was completed, 10 g of an antioxidant was added and mixed evenly. Finally, granulation was carried out through a twin-screw extruder. The screw length-diameter ratio of the twin-screw extruder was 40:1, the screw speed was 350 rpm, and the extrusion temperature was 250 ° C. To obtain a flame-retardant nylon cable sheath material. Example 3

[0049] In this embodiment, based on the method of Example 1, the amounts of components used in preparing the flame-retardant nylon cable sheath material are adjusted as follows:

[0050] 700 g of PA6, 57 g of melamine-carboxylated silica modified chitosan composite, 4 g of a cross-linking agent and 4 g of a lubricant were placed in a vacuum reactor, wherein the cross-linking agent was prepared by mixing triallyl isocyanurate TAIC and trimethylallyl isocyanurate TMAIC in a weight ratio of 3:1, and the mixture was fully stirred and mixed at a temperature of 155 ° C. The obtained mixture was cooled to room temperature, then flattened and irradiated. The irradiation processing conditions were electron beam, and the irradiation dose was 100 kGy. After the irradiation was completed, 13 g of an antioxidant was added and mixed evenly. Finally, granulation was carried out through a twin-screw extruder. The screw length-diameter ratio of the twin-screw extruder was 40:1, the screw speed was 350 rpm, and the extrusion temperature was 270 ° C. To obtain a flame-retardant nylon cable sheath material. Example 4

[0051] In this embodiment, based on the method of Example 1, the component dosage and process parameters for preparing the flame-retardant nylon cable sheath material are adjusted as follows:

[0052] 950 g of PA6, 77 g of melamine-carboxylated silica modified chitosan composite, 6 g of crosslinking agent and 6 g of lubricant were placed in a vacuum reactor, wherein the crosslinking agent was prepared by mixing triallyl isocyanurate TAIC and trimethylallyl isocyanurate TMAIC in a weight ratio of 3:1, and the mixture was fully stirred and mixed at a temperature of 160 ° C. The obtained mixture was cooled to room temperature, then flattened and irradiated. The irradiation processing conditions were electron beam, and the irradiation dose was 100 kGy. After the irradiation was completed, 18 g of antioxidant was added and mixed evenly. Finally, granulation was carried out through a twin-screw extruder. The screw length-diameter ratio of the twin-screw extruder was 40:1, the screw speed was 350 rpm, and the extrusion temperature was 280 ° C. To obtain a flame-retardant nylon cable sheath material. Example 5

[0053] In this embodiment, based on the method of Example 1, the amounts of components used in preparing the flame-retardant nylon cable sheath material are adjusted as follows:

[0054] 800g of PA6, 60g of melamine-carboxylated silica modified chitosan composite, 5g of crosslinking agent and 5g of lubricant are placed in a vacuum reactor, wherein the crosslinking agent is prepared by mixing triallyl isocyanurate TAIC and trimethylallyl isocyanurate TMAIC in a weight ratio of 3:1, and the mixture is fully stirred and mixed at a temperature of 155°C. The obtained mixture is cooled to room temperature, then flattened and irradiated. The irradiation processing conditions are electron beam, and the irradiation dose is 100kGy. After the irradiation is completed, 15g of antioxidant is added and mixed evenly. Finally, granulation is carried out through a twin-screw extruder. The screw length-diameter ratio of the twin-screw extruder is 40:1, the screw speed is 350rpm, and the extrusion temperature is 270°C to obtain a flame-retardant nylon cable sheath material.

[0055] In Examples 6 and 7, based on the method of Example 1, the preparation parameters of the melamine-carboxylated silica-modified chitosan composite were adjusted. Specifically, in Example 6, the weight ratio of melamine to carboxylated silica-modified chitosan composite was adjusted to 8:1; and in Example 7, the weight ratio of melamine to carboxylated silica-modified chitosan composite was adjusted to 10:1.

[0056] In Examples 8 and 9, based on the method of Example 1, the preparation parameters of the carboxylated silica-modified chitosan were adjusted. Specifically, in Example 8, the weight ratio of carboxylated silica to chitosan was adjusted to 1:1; and in Example 9, the weight ratio of melamine to carboxylated silica-modified chitosan composite was adjusted to 1.5:1.

[0057] Examples 10-14, based on the method of Example 1, adjusted the crosslinking agent in the flame-retardant nylon cable sheath material component. The crosslinking agent used in Example 10 was triallyl cyanurate (TAC); the crosslinking agent used in Example 11 was triallyl isocyanurate (TAIC); the crosslinking agent used in Example 12 was trimethylallyl isocyanurate (TMAIC); the crosslinking agent used in Example 13 was a mixture of triallyl isocyanurate (TAIC) and trimethylallyl isocyanurate (TMMAIC) in a weight ratio of 1:1; and the crosslinking agent used in Example 14 was a mixture of triallyl isocyanurate (TAIC) and trimethylolpropane trimethacrylate (TMPTMA) in a weight ratio of 3:1. Example 15

[0058] In this embodiment, based on the method of Example 1, the preparation method of the flame-retardant nylon cable sheath material is adjusted, that is, extrusion granulation is first performed followed by irradiation cross-linking. The specific steps are as follows:

[0059] 800 g of PA6, 65 g of melamine-carboxylated silica modified chitosan composite, 5 g of cross-linking agent, 5 g of lubricant and 15 g of antioxidant were mixed evenly and then added to a twin-screw extruder for granulation. The twin-screw extruder had a screw length-to-diameter ratio of 40:1, a screw speed of 350 rpm, and an extrusion temperature of 270 ° C. The obtained particles were put into an injection molding machine for extrusion at an extrusion temperature of 240 ° C. The thickness of the extruded cable sheath was 1.5 ± 0.01 mm, and then irradiated. The irradiation processing conditions were electron beam and the irradiation dose was 100 kGy. The flame-retardant nylon cable sheath was obtained as the sample to be tested. Comparative Example Comparative Example 1

[0060] In this comparative example, based on the method of Example 1, the melamine-carboxylated silica modified chitosan composite was replaced with a mixture of equal amounts of melamine, carboxylated silica and chitosan, namely, 58.5 g of melamine, 3.55 g of carboxylated silica and 2.95 g of chitosan were stirred and mixed. Comparative Example 2

[0061] In this comparative example, based on the method of Example 1, the melamine-carboxylated silica modified chitosan composite was replaced with an equal amount of carboxylated silica modified chitosan. Comparative Example 3

[0062] In this comparative example, based on the method of Example 1, the melamine-carboxylated silica modified chitosan composite was replaced with an equal amount of chitosan phosphate melamine salt flame retardant.

[0063] Performance testing

[0064] The samples prepared in Examples 1-15 and Comparative Examples 1-3 were subjected to the following performance tests. The test results are shown in Table 1 below.

[0065] 1. High temperature resistance: Use electric soldering iron to test (melt sink depth). The test method is to use electric soldering iron with a heating contact of 2mm in diameter and 5mm in height at 400℃. The test contact is vertically contacted with the surface of the sample to be tested with a load of 1kg. The test is maintained for 3 minutes. The test head is removed and the depth of the melt sink at the contact point is measured (μm).

[0066] 2. Flame retardant performance: It is expressed by the limiting oxygen index (%) of the oxygen index test and the flame retardant grade (level) of the vertical burning method test. When testing the oxygen index, the sample to be tested is cut into 50mmx6mm strips, and the oxygen concentration is 30%; when testing the vertical burning method, 1.6mm is burned. The higher the limiting oxygen index and flame retardant grade, the better the flame retardant performance.

[0067] 3. Mechanical properties: expressed in tensile strength (MPa). The greater the tensile strength, the better the mechanical properties.

[0068] Table 1 Performance test table of Examples 1-15 and Comparative Examples 1-3

[0069] Melt depth / μm Limiting oxygen index / % Flame retardant grade / level Tensile strength / MPa Example 1 10 38.5 V0 81.2 Example 2 15 33.2 V0 78.5 Example 3 11 37.1 V0 79.0 Example 4 12 36.7 V0 79.5 Example 5 23 30.7 V0 73.1 Example 6 20 35.9 V0 78.6 Example 7 17 37.0 V0 74.9 Example 8 34 35.2 V0 70.5 Example 9 13 36.4 V0 73.8 Example 10 38 37.8 V0 67.2 Example 11 26 37.8 V0 69.7 Example 12 31 37.9 V0 69.0 Example 13 19 38.2 V0 72.2 Example 14 24 38.0 V0 73.1 Example 15 18 36.7 V0 78.9 Comparative Example 1 153 23.8 V1 41.5 Comparative Example 2 109 25.1 V1 46.5 Comparative Example 3 64 30.6 V0 48.2

[0070] In combination with Table 1 above, by comparing the test results of Examples 1-15 of the present application with those of Comparative Examples 1-3, it can be concluded that, compared with the method of adding the three separately, adding carboxylated silica-modified chitosan alone, or using other composite flame retardants such as chitosan phosphate melamine salt flame retardants, the present application uses a composite material of melamine, silica and chitosan as one, which can better reduce the degree of instantaneous melting of the PA material caused by local instantaneous high heat, thereby effectively improving the high temperature resistance of the flame retardant nylon cable sheath material; and the flame retardant nylon cable sheath material obtained by cross-linking and modifying the nylon with a cross-linking agent not only has excellent high temperature resistance and flame retardant properties, but also has high mechanical properties.

[0071] By comparing the test results of Example 1 with those of Examples 6 to 7, it can be concluded that in the melamine-carboxylated silica modified chitosan composite of the present application, when the weight ratio of melamine to carboxylated silica modified chitosan composite is 9:1, a flame retardant nylon cable sheath material with better high temperature resistance, flame retardant properties and mechanical properties can be obtained.

[0072] By comparing the test results of Example 1 with those of Examples 8 to 9, it can be concluded that in the melamine-carboxylated silica modified chitosan composite of the present application, when the weight ratio of carboxylated silica to chitosan is 1.2:1, a flame-retardant nylon cable sheath material with better high temperature resistance, flame retardant properties and mechanical properties can be obtained.

[0073] By comparing the test results of Example 1 with those of Examples 10-14, it can be concluded that in the flame-retardant nylon cable sheath material component of the present application, when the cross-linking agent is a mixture of triallyl isocyanurate and trimethylallyl isocyanurate in a weight ratio of 3:1, the performance of the flame-retardant nylon cable sheath material obtained is significantly better than others, and therefore it is further preferred.

[0074] Comparing the test results of Example 1 with those of Example 15, we can conclude that by mixing PA6 with a melamine-carboxylated silica-modified chitosan composite, a crosslinker, and a lubricant, followed by radiation crosslinking, the present invention can produce a flame-retardant nylon cable sheath material with superior high-temperature resistance and mechanical properties. Compared to irradiating and crosslinking after the finished product is made, this also avoids radiation denaturation of other materials within the cable sheath, thereby meeting the cable's operational requirements.

[0075] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A flame retardant nylon cable sheath material, characterized in that: The invention comprises the following components in parts by weight: 55-95 parts of PA6, 4.5-7.7 parts of melamine-carboxylated silicon dioxide modified chitosan composite, 0.3-0.6 parts of crosslinking agent, 0.3-0.6 parts of lubricant, and 1-1.8 parts of antioxidant; The preparation method of the melamine-carboxylated silica modified chitosan composite comprises the following steps: taking melamine and dispersing it evenly with methanol, then adding carboxylated silica modified chitosan to react, wherein the weight ratio of the melamine to the carboxylated silica modified chitosan is 9:1, and filtering and drying to obtain the composite; The cross-linking agent is prepared by mixing triallyl isocyanurate and trimethylallyl isocyanurate in a weight ratio of 3:

1. The preparation method of the carboxylated silica-modified chitosan comprises the following steps: dispersing silica in an ether solution, slowly adding succinic anhydride, and filtering and drying after the reaction is completed to obtain carboxylated silica; dispersing chitosan in n-butanol, slowly adding carboxylated silica, and filtering and drying after the reaction is completed to obtain the carboxylated silica-modified chitosan; the weight ratio of the carboxylated silica to the chitosan is 1.2:

1.

2. The flame-retardant nylon cable sheath material according to claim 1, characterized in that: The lubricant is selected from one or more of silicone, stearic acid, stearate, pentaerythritol stearate, organosiloxane, polyester wax, inter amide, and alkane wax.

3. The flame-retardant nylon cable sheath material according to claim 1, characterized in that: The antioxidant is selected from one or more of hindered phenols and phosphite antioxidants.

4. The method for preparing the flame-retardant nylon cable sheath material according to any one of claims 1 to 3, characterized in that: The following steps are involved: A set amount of PA6, melamine-carboxylated silica modified chitosan composite, crosslinking agent and lubricant are placed in a vacuum reactor and fully stirred and mixed at a temperature of 150-160°C. The obtained mixture is cooled to room temperature and then flattened and irradiated. After the irradiation is completed, a set amount of antioxidant is added and mixed evenly. Finally, granulation is carried out through a twin-screw extruder at an extrusion temperature of 250-280°C to obtain the flame-retardant nylon cable sheath material.