High-flame-retardancy low-smoke halogen-free cable sheath material and preparation method thereof

Abstract

The invention relates to the technical field of materials, and discloses a high-flame-retardancy low-smoke halogen-free cable sheath material and a preparation method thereof.The cable sheath material is prepared by taking a polyvinyl base material as a main raw material and taking a flexibilizer, a flame retardant and the like as auxiliary materials through mixing and extrusion processes; wherein the flame retardant is prepared by cross-linking galactomannan by using a triazine derivative containing a phosphorus flame-retardant element in the structure as a cross-linking agent, the galactomannan can be used as a carbon source, a triazine ring can be used as a nitrogen source, and the phosphorus flame retardant can be used as an acid source, so that a three-element integrated intumescent flame-retardant system can be formed, and the flame-retardant effect is good when combustion occurs. An expanded carbon layer can be rapidly formed on the surface of the sheath material, the expanded carbon layer can effectively isolate oxygen, heat and a fire source, then the flame retardant property of the sheath material is effectively improved, the aerogel structure has rich pores, smoke formed by combustion can be effectively absorbed, and the flame retardant property of the sheath material is improved. Therefore, low-smoke halogen-free modification of polyethylene is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of materials, in particular to a high-flame-retardant low-smoke halogen-free cable sheath material and a preparation method thereof. BACKGROUND

[0002] In the complex network of modern society, cables like blood vessels and nerves of the human body, undertake the key task of power transmission and information communication. And the cable sheath material, as the outermost protective barrier of the cable, plays a crucial role in ensuring the stable operation of the cable and prolonging the service life.

[0003] At present, the sheath material of the cable generally uses high molecular substances as the base material, cooperates with various functional additives, and is prepared by melt extrusion process. Among the many high molecular substances, polyethylene is well known for its good electrical insulation performance and water resistance. Its dielectric constant and dielectric loss tangent value are relatively low, which can effectively reduce the energy loss of the cable during transmission. Polyethylene also has excellent low temperature resistance and can maintain good flexibility and mechanical strength in low temperature environment, and is suitable for cable laying in cold regions. However, polyethylene itself is a flammable material, and it is easy to melt and drip and produce a large amount of smoke when burning, with high risk of fire spreading, which poses a potential safety threat, which greatly limits its application in the field of cable sheath materials.

[0004] At present, the way to improve the flame retardant performance of polyethylene by adding flame retardants is a common modification scheme, but various flame retardants have certain defects in actual application, such as inorganic flame retardants which need a large amount of addition to play a significant effect, are easy to have a negative effect on the mechanical properties of polyethylene, halogen-based flame retardants have greater environmental hazards and are not suitable for continued use, phosphorus-based halogen-free flame retardants have good performance in all aspects, but cannot effectively absorb smoke, and there are certain interface problems between the polyethylene matrix and the flame retardant, so the long-term flame retardant effect cannot be guaranteed. Therefore, the present application provides a polyethylene cable sheath material with good halogen-free flame-retardant low-smoke performance, which can solve the problems in the prior art. SUMMARY

[0005] (I) Technical problems to be solved

[0006] In view of the deficiencies of the prior art, the present application provides a high-flame-retardant low-smoke halogen-free cable sheath material and a preparation method thereof.

[0007] (II) Technical solutions

[0008] A high-flame-retardant low-smoke halogen-free cable sheath material, according to weight parts, comprises the following raw materials:

[0009] 70-85 parts of polyethylene base material, 15-25 parts of toughening agent, 5-10 parts of interfacial compatibilizer, 2-4.5 parts of flame retardant, 0.5-1.5 parts of composite antioxidant, 1-3 parts of lubricant, 5-10 parts of inorganic filler, 3-6 parts of silane coupling agent;

[0010] The flame retardant is prepared by cross-linking galactomannan using a triazine derivative containing a phosphorus flame retardant element in its structure as a cross-linking agent.

[0011] As a further solution of the present invention, the toughening agent is any one of EPDM rubber, styrene-butadiene rubber, nitrile rubber or polybutadiene rubber; and the interfacial compatibilizer is maleic anhydride grafted polypropylene.

[0012] As a further embodiment of the present invention, the method for preparing the flame retardant comprises the following steps:

[0013] Step S1, adding galactomannan to an ethanol aqueous solution, stirring after the addition is completed, and then adding a crosslinking agent and a catalyst to the uniform solution. After the addition is completed, the temperature is increased to 30-40° C. and kept warm for 12-18 hours to form a precursor;

[0014] Step S2: pour the precursor into a mold and cool it. After it is gelled, place it in a freeze dryer for freeze drying to obtain a flame retardant.

[0015] As a further embodiment of the present invention, in step S1, the cross-linking agent is prepared as follows:

[0016] Dihydro-2,4,6-trioxo-1,3,5-triazine-1,3(2H,4H)-dipropionic acid is added to toluene and stirred until completely dissolved to form a reaction liquid. Then, nitrogen is introduced for protection. A halogenated phosphorus flame retardant is added to the reaction liquid under stirring, and a sodium hydroxide aqueous solution is added dropwise. After the addition is completed, the temperature is raised to 70-80°C and kept warm for 4-8 hours. Then, the heating is stopped, the temperature is lowered and the material is discharged. The product is purified to obtain a cross-linking agent.

[0017] As a further embodiment of the present invention, the halogenated phosphorus flame retardant is di-tert-butyl chloromethyl phosphate or tris(2-chloroethyl) phosphate.

[0018] As a further embodiment of the present invention, the molar ratio of the dihydro-2,4,6-trioxo-1,3,5-triazine-1,3(2H,4H)-dipropionic acid to the halogenated phosphorus flame retardant is 1:1-3.

[0019] As a further embodiment of the present invention, the mass fraction of the sodium hydroxide aqueous solution is 15-30%.

[0020] As a further scheme of the present application, in step S1, the catalyst is a mixture of N-hydroxysuccinimide and dicyclohexyl carbodiimide, with a mass ratio of 1:3-4.

[0021] In the above technical solution, first, dihydro-2,4,6-trioxo-1,3,5-triazine-1,3(2H,4H)-dipropionic acid and halogenated phosphorus flame retardant are used as reactants, under the action of sodium hydroxide, the secondary amine in the structure of each other can be substituted with halogen substituent group to prepare triazine derivative containing phosphorus flame retardant element, i.e. crosslinking agent, because the structure contains two or more active carboxyl substituents, under the action of catalyst, the active carboxyl substituent can continuously esterify and condense with the hydroxyl substituent in the structure of galactomannan to realize the crosslinking of galactomannan, and the precursor is prepared, and then the precursor is freeze-dried to prepare the galactomannan-based flame retardant with aerogel structure.

[0022] As a further scheme of the present application, the composite antioxidant is a mixture of lignin and antioxidant 1010, with a mass ratio of 1:0.2-0.3; the lubricant is polyethylene wax or paraffin wax; the inorganic filler is any one of calcium carbonate, titanium white, talc, silicon dioxide or carbon black; and the silane coupling agent is 3-aminopropyl trimethoxysilane or 3-aminopropyl triethoxysilane.

[0023] A preparation method of a high-flame-retardant low-smoke halogen-free cable sheath material, comprising the following steps:

[0024] Firstly, each raw material is weighed and prepared according to the weight fraction;

[0025] Secondly, each raw material is added to a high-speed mixer, the rotating speed is controlled to be 1000-1500 r / min, and after mechanical stirring for 10-20 min, the formed mixture is fed into a double-screw extruder through a feeding hopper, and then melt extrusion granulation is carried out.

[0026] (Three) beneficial technical effects

[0027] The galactomannan contained in the structure of the flame retardant prepared in the present application can be used as a carbon source, the triazine ring can be used as a nitrogen source, and the phosphorus flame retardant can be used as an acid source, so that a ternary integrated intumescent flame retardant system is formed, when combustion occurs, an expanded carbon layer can be rapidly formed on the surface of the sheath material, the expanded carbon layer can effectively isolate oxygen, heat and fire source, and protect the inside of the sheath material, so that the purpose of greatly improving the flame retardant performance of the sheath material can be achieved by adding a small amount, in addition, because the flame retardant has an aerogel structure and has abundant pores, the smoke formed by combustion can be effectively absorbed, so that the low-smoke halogen-free modification of polyethylene is realized. Specific embodiment

[0028] For the purpose of promoting the understanding of the present application, a more comprehensive description will be given below. The following presents the preferred embodiments of the present application. However, the present application can be carried out in a multitude of different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete. It is therefore desirable that the present application be viewed broadly.

[0029] Preparation Example

[0030] Preparation of the flame retardant:

[0031] Step one, 0.3g of dihydro-2,4,6-trioxo-1,3,5-triazine-1,3(2H,4H)-dipropionic acid is added to toluene, stirred until completely dissolved to form a reaction solution, then nitrogen is introduced for protection, 0.3g of di-tert-butyl chloromethyl phosphate is added to the reaction solution under stirring, and 10mL of 20% sodium hydroxide aqueous solution is added dropwise, after the addition is completed, the temperature is increased to 75℃, and the incubation is continued for 6h, then the heating is stopped, the temperature is lowered, and the product is obtained by purification treatment, i.e. the crosslinking agent is obtained;

[0032] Step two, 1.2g of galactomannan is added to an ethanol aqueous solution, after the addition is completed, the stirring is started, and after a uniform solution is formed, 0.2g of the crosslinking agent, 0.1g of N-hydroxysuccinimide and 0.4g of dicyclohexyl carbodiimide are added to the uniform solution, after the addition is completed, the temperature is increased to 35℃, and the incubation is continued for 16h, to form a precursor;

[0033] Step three, the precursor is poured into a mold and cooled, after it is gelled, it is placed in a freeze dryer, and freeze-dried at a temperature of -40℃ for 24h, to obtain the flame retardant.

[0034] Example 1

[0035] A high-flame-retardant low-smoke halogen-free cable sheath material, according to the weight fraction, includes the following raw materials:

[0036] Polyethylene base 70 parts, ethylene-propylene-diene rubber 15 parts, maleic anhydride grafted polypropylene 5 parts, flame retardant 2 parts, composite antioxidant 0.5 parts, polyethylene wax 1 part, calcium carbonate 5 parts, 3-aminopropyltrimethoxysilane 3 parts;

[0037] The preparation method of the cable sheath material includes the following steps:

[0038] First step, the raw materials are weighed according to the weight fraction and prepared;

[0039] Second step, each raw material is added to the high-speed mixer, the speed is controlled at 1000r / min, after mechanical stirring for 20 minutes, the formed mixture is fed into the double screw extruder through the feeding hopper, the temperature of each zone is controlled at: 200℃ for the first zone, 210℃ for the second zone, 220℃ for the third zone, 220℃ for the fourth zone, and 210℃ for the fifth zone, and then the melting extrusion granulation is carried out.

[0040] The preparation method of the flame retardant is shown in the preparation example; the composite antioxidant is a mixture of lignin and antioxidant 1010 with a mass ratio of 1:0.3; the following are the same.

[0041] Example 2

[0042] A high-flame-retardant low-smoke halogen-free cable sheath material includes the following raw materials in parts by weight:

[0043] Polyethylene base material 75 parts, styrene butadiene rubber 18 parts, maleic anhydride grafted polypropylene 8 parts, flame retardant 4 parts, composite antioxidant 1 part, paraffin wax 2 parts, titanium dioxide 6 parts, 3-aminopropyl triethoxysilane 5 parts;

[0044] The preparation method of the cable sheath material includes the following steps:

[0045] First step, each raw material is weighed according to the weight fraction and prepared;

[0046] Second step, each raw material is added to the high-speed mixer, the speed is controlled at 1200r / min, after mechanical stirring for 15 minutes, the formed mixture is fed into the double screw extruder through the feeding hopper, the temperature of each zone is controlled at: 200℃ for the first zone, 210℃ for the second zone, 220℃ for the third zone, 220℃ for the fourth zone, and 210℃ for the fifth zone, and then the melting extrusion granulation is carried out.

[0047] Example 3

[0048] A high-flame-retardant low-smoke halogen-free cable sheath material includes the following raw materials in parts by weight:

[0049] Polyethylene base material 85 parts, styrene butadiene rubber 25 parts, maleic anhydride grafted polypropylene 10 parts, flame retardant 4.5 parts, composite antioxidant 1.5 parts, paraffin wax 3 parts, talc 10 parts, 3-aminopropyl triethoxysilane 6 parts;

[0050] The preparation method of the cable sheath material includes the following steps:

[0051] First step, each raw material is weighed according to the weight fraction and prepared;

[0052] Second step, each raw material is added to the high-speed blender, the speed is controlled at 1500r / min, mechanical stirring is carried out for 10 minutes, then the formed mixture is fed into the double-screw extruder through the feeding hopper, the temperature of each zone is controlled at: 200℃ for the first zone, 210℃ for the second zone, 220℃ for the third zone, 220℃ for the fourth zone, and 210℃ for the fifth zone, and then melting extrusion granulation is carried out.

[0053] Comparative example 1

[0054] A high-flame-retardant low-smoke halogen-free cable sheath material comprises the following raw materials in parts by weight:

[0055] 75 parts of polyethylene base material, 18 parts of butadiene styrene rubber, 8 parts of maleic anhydride grafted polypropylene, 4 parts of di-t-butyl chloromethyl phosphate, 1 part of composite antioxidant, 2 parts of paraffin wax, 6 parts of titanium white, and 5 parts of 3-aminopropyl triethoxysilane;

[0056] The preparation method of the cable sheath material comprises the following steps:

[0057] First step, each raw material is weighed according to the weight fraction and prepared in advance;

[0058] Second step, each raw material is added to the high-speed blender, the speed is controlled at 1200r / min, mechanical stirring is carried out for 15 minutes, then the formed mixture is fed into the double-screw extruder through the feeding hopper, the temperature of each zone is controlled at: 200℃ for the first zone, 210℃ for the second zone, 220℃ for the third zone, 220℃ for the fourth zone, and 210℃ for the fifth zone, and then melting extrusion granulation is carried out.

[0059] Comparative example 2

[0060] A high-flame-retardant low-smoke halogen-free cable sheath material comprises the following raw materials in parts by weight:

[0061] 75 parts of polyethylene base material, 18 parts of butadiene styrene rubber, 8 parts of maleic anhydride grafted polypropylene, 1 part of composite antioxidant, 2 parts of paraffin wax, 6 parts of titanium white, and 5 parts of 3-aminopropyl triethoxysilane;

[0062] The preparation method of the cable sheath material comprises the following steps:

[0063] First step, each raw material is weighed according to the weight fraction and prepared in advance;

[0064] Second step, each raw material is added to the high-speed blender, the speed is controlled at 1200r / min, mechanical stirring is carried out for 15 minutes, then the formed mixture is fed into the double-screw extruder through the feeding hopper, the temperature of each zone is controlled at: 200℃ for the first zone, 210℃ for the second zone, 220℃ for the third zone, 220℃ for the fourth zone, and 210℃ for the fifth zone, and then melting extrusion granulation is carried out.

[0065] Performance test

[0066] The sheathing materials in the examples and comparative examples were made into each specification-compliant test sample, after being placed at room temperature for 3 months, the flame retardant performance test was carried out, and the results are recorded in the following table:

[0067] Table 1 - Test results

[0068] Limiting oxygen index / % Smoke density (flaming) Test standard GB / T 2406.2-2009 GB / T 8323.2-2008 Example 1 33.1 69 Example 2 33.4 65 Example 3 33.3 66 Comparative Example 1 28.9 98 Comparative Example 2 19.4 129

[0069] It can be seen from the analysis of the test results that the sheathing material prepared in the examples of the present application has excellent flame retardant performance, and low smoke density, and has low smoke characteristics.

[0070] After the flame retardant is replaced by the conventional phosphorus-containing flame retardant di-t-butyl chloromethyl phosphate, the flame retardant performance decreases significantly, and it can be analyzed that the phosphorus-containing flame retardant alone cannot achieve the effect that a small amount of addition of intumescent flame retardant can greatly enhance the flame retardant performance of polyethylene.

[0071] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0072] According to the ideal embodiments of the present application, through the above description, the relevant personnel can make various changes and modifications without deviating from the scope of the technical idea of the present application. The technical scope of the present application is not limited to the content of the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A highly flame retardant, low smoke, halogen-free cable sheath material, characterized in that: According to parts by weight, the following raw materials are included: 70-85 parts of polyethylene base material, 15-25 parts of toughening agent, 5-10 parts of interfacial compatibilizer, 2-4.5 parts of flame retardant, 0.5-1.5 parts of composite antioxidant, 1-3 parts of lubricant, 5-10 parts of inorganic filler, 3-6 parts of silane coupling agent; The flame retardant is prepared by cross-linking galactomannan using a triazine derivative containing a phosphorus flame retardant element in its structure as a cross-linking agent.

2. The highly flame-retardant low-smoke zero-halogen cable sheath material according to claim 1, characterized in that: The toughening agent is any one of EPDM rubber, styrene-butadiene rubber, nitrile rubber or polybutadiene rubber; and the interfacial compatibilizer is maleic anhydride grafted polypropylene.

3. The highly flame retardant low smoke zero halogen cable sheath material according to claim 1, characterized in that: The preparation method of the flame retardant comprises the following steps: Step S1, adding galactomannan to an ethanol aqueous solution, stirring after the addition is completed, and then adding a crosslinking agent and a catalyst to the uniform solution. After the addition is completed, the temperature is increased to 30-40° C. and kept warm for 12-18 hours to form a precursor; Step S2: pour the precursor into a mold and cool it. After it is gelled, place it in a freeze dryer for freeze drying to obtain a flame retardant.

4. The highly flame-retardant low-smoke zero-halogen cable sheath material according to claim 3, characterized in that: In step S1, the preparation method of the cross-linking agent is as follows: Dihydro-2,4,6-trioxo-1,3,5-triazine-1,3(2H,4H)-dipropionic acid is added to toluene and stirred until completely dissolved to form a reaction liquid. Then, nitrogen is introduced for protection. A halogenated phosphorus flame retardant is added to the reaction liquid under stirring, and a sodium hydroxide aqueous solution is added dropwise. After the addition is completed, the temperature is raised to 70-80°C and kept warm for 4-8 hours. Then, the heating is stopped, the temperature is lowered and the material is discharged. The product is purified to obtain a cross-linking agent.

5. The highly flame retardant low smoke zero halogen cable sheath material according to claim 4, characterized in that: The halogenated phosphorus flame retardant is di-tert-butyl chloromethyl phosphate or tris(2-chloroethyl) phosphate.

6. The highly flame retardant low smoke zero halogen cable sheath material according to claim 4, characterized in that: The molar ratio of the dihydro-2,4,6-trioxo-1,3,5-triazine-1,3(2H,4H)-dipropionic acid to the halogenated phosphorus flame retardant is 1:1-3.

7. The highly flame retardant low smoke zero halogen cable sheath material according to claim 4, characterized in that: The mass fraction of the sodium hydroxide aqueous solution is 15-30%.

8. The highly flame-retardant, low-smoke, halogen-free cable sheath material according to claim 4, characterized in that: In step S1, the catalyst is a mixture of N-hydroxysuccinimide and dicyclohexylcarbodiimide in a mass ratio of 1:3-4.

9. The highly flame retardant low smoke zero halogen cable sheath material according to claim 1, characterized in that: The composite antioxidant is a mixture of lignin and antioxidant 1010, with a mass ratio of 1:0.2-0.3; the lubricant is polyethylene wax or paraffin; the inorganic filler is any one of calcium carbonate, titanium dioxide, talc, silica or carbon black; and the silane coupling agent is 3-aminopropyltrimethoxysilane or 3-aminopropyltriethoxysilane.

10. A method for preparing the highly flame-retardant low-smoke zero-halogen cable sheath material according to claim 1, characterized in that: The following steps are involved: The first step is to weigh and prepare all the raw materials according to their weight; The second step is to add all the raw materials into a high-speed mixer, control the speed to 1000-1500r / min, and mechanically stir for 10-20 minutes, then feed the formed mixture into a twin-screw extruder through a feeding hopper for melt extrusion and granulation.