A medium voltage flame retardant cable and preparation method thereof

Abstract

The present invention relates to the field of cable technology, and proposes a medium-voltage flame-retardant cable and a preparation method thereof. The medium-voltage flame-retardant cable comprises a conductor, an insulating layer, a flame-retardant layer and a sheath layer arranged in sequence from the inside to the outside, and the raw materials of the flame-retardant layer include the following components in parts by weight: 100 parts of polyethylene, 20-30 parts of acetic acid-vinyl acetate copolymer, 40-60 parts of modified nano aluminum hydroxide, 2-4 parts of antioxidant, and 1-3 parts of lubricant; the raw materials of the modified nano aluminum hydroxide include cellulose derivatives and nano aluminum hydroxide; the weight ratio of cellulose derivatives to nano aluminum hydroxide is 1-5:30. Through the above technical scheme, the problem of low oxygen index and tensile strength of the flame-retardant layer of the medium-voltage flame-retardant cable in the related art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and in particular to a medium voltage flame retardant cable and a preparation method thereof. Background Art

[0002] Medium voltage flame retardant cable is a flame retardant cable suitable for power systems with voltage levels of 6kV to 35kV. It is widely used in urban power grids, industrial enterprises and large buildings. For example, transmission lines between urban substations, power distribution systems in factories and power supply systems in high-rise buildings.

[0003] The flame retardant performance of medium voltage flame retardant cables mainly depends on the flame retardant layer. The flame retardant layer can prevent or slow down the spread of flames when a fire occurs, reduce the damage to the cable, and reduce the hazards of fire. At present, the flame retardant layer of the existing medium voltage flame retardant cable has two shortcomings: first, the oxygen index is low and the flame retardant effect is not good; second, the flame retardant is not easy to disperse after being added, resulting in low tensile strength of the flame retardant layer. In view of this, in order to improve the product quality of medium voltage flame retardant cables, it is of great significance to develop a medium voltage flame retardant cable with a high oxygen index and tensile strength of the flame retardant layer. Summary of the invention

[0004] The invention provides a medium voltage flame retardant cable and a preparation method thereof, which solves the problem of low oxygen index and tensile strength of the flame retardant layer of the medium voltage flame retardant cable in the related art.

[0005] The technical solution of the present invention is as follows:

[0006] The present invention provides a medium voltage flame retardant cable, comprising a conductor, an insulating layer, a flame retardant layer and a sheath layer arranged in sequence from the inside to the outside, wherein the raw materials of the flame retardant layer comprise the following components in parts by weight: 100 parts of polyethylene, 20-30 parts of acetic acid-vinyl acetate copolymer, 40-60 parts of modified nano aluminum hydroxide, 2-4 parts of antioxidant, and 1-3 parts of lubricant;

[0007] The raw materials of the modified nano aluminum hydroxide include cellulose derivatives and nano aluminum hydroxide;

[0008] The weight ratio of the cellulose derivative to the nano-aluminum hydroxide is 1-5:30.

[0009] As a further technical solution, the particle size of the nano aluminum hydroxide is 20~50nm.

[0010] As a further technical solution, the preparation method of the modified nano aluminum hydroxide comprises the following steps: dissolving a cellulose derivative in N,N-dimethylformamide, adding nano aluminum hydroxide, dispersing evenly, and drying to obtain the modified nano aluminum hydroxide.

[0011] As a further technical solution, the cellulose derivatives include cellulose ethers and cellulose esters;

[0012] The weight ratio of the cellulose ether to the cellulose ester is 1:4 to 4:1.

[0013] In the present invention, when the cellulose derivatives include cellulose ether and cellulose ester, the modification effect of the nano aluminum hydroxide can be further improved through the synergistic effect of two different types of cellulose derivatives, thereby further improving the oxygen index and tensile strength of the flame retardant layer.

[0014] As a further technical solution, the cellulose ether includes one of hydroxyethyl cellulose and carboxymethyl cellulose, preferably hydroxyethyl cellulose.

[0015] As a further technical solution, the cellulose ester includes one of cellulose acetate and cellulose acetate butyrate, preferably cellulose acetate.

[0016] As a further technical solution, the weight of the cellulose ester is greater than the weight of the cellulose ether.

[0017] In the present invention, when the weight of cellulose ester is greater than the weight of cellulose ether, it helps to further improve the oxygen index and tensile strength of the flame retardant layer.

[0018] As a further technical solution, the raw material of the modified nano aluminum hydroxide also includes potassium cetyl alcohol phosphate;

[0019] The weight ratio of the potassium cetyl phosphate to the nano aluminum hydroxide is 1-5:60.

[0020] In the present invention, the inventors found that when the raw materials of the modified nano aluminum hydroxide also include potassium cetyl phosphate, the oxygen index and tensile strength of the flame retardant layer can be further improved. It is speculated that the addition of potassium cetyl phosphate is conducive to enhancing the film-forming effect of cellulose derivatives on the surface of nano aluminum hydroxide, thereby further improving the dispersion ability of nano aluminum hydroxide in the flame retardant layer, and further improving the oxygen index and tensile strength of the flame retardant layer.

[0021] As a further technical solution, the antioxidant includes one or more of antioxidant 1076 , antioxidant 168 , and antioxidant 300 .

[0022] In the present invention, the addition of an antioxidant can improve the stability of the flame retardant layer and extend the service life of the flame retardant layer.

[0023] As a further technical solution, the lubricant includes one or more of stearic acid, calcium stearate, and solid paraffin.

[0024] In the present invention, the addition of lubricant can promote the flow of the raw materials of the flame retardant layer, reduce friction resistance and increase the preparation rate.

[0025] As a further technical solution, the conductor includes one of a copper conductor and an aluminum conductor.

[0026] As a further technical solution, the raw material of the insulating layer includes one of cross-linked polyethylene, polyethylene, and polypropylene.

[0027] In the present invention, the insulating layer plays an insulating role and can prevent current leakage and short circuit between conductors.

[0028] As a further technical solution, the raw material of the sheath layer includes one of polyvinyl chloride and polyethylene.

[0029] In the present invention, the sheath layer is used to protect the structure of the medium voltage flame retardant cable to prevent it from being damaged by external forces during the laying and use process.

[0030] The present invention also provides a method for preparing a medium voltage flame-retardant cable, comprising the following steps:

[0031] S1, mixing, extruding and pelletizing the raw materials of the flame retardant layer to obtain a masterbatch of the flame retardant layer;

[0032] S2. From the inside to the outside, in the order of the insulating layer, the flame retardant layer masterbatch and the sheath layer, the raw material of the insulating layer, the flame retardant layer masterbatch and the raw material of the sheath layer are sequentially extruded on the surface of the conductor to obtain a medium voltage flame retardant cable.

[0033] As a further technical solution, in step S1, the temperature during extrusion is 100-150°C.

[0034] The working principle and beneficial effects of the present invention are:

[0035] In the present invention, the flame retardant layer of the medium voltage flame retardant cable includes modified nano aluminum hydroxide. The nano aluminum hydroxide is modified by cellulose derivatives to prevent the nano aluminum hydroxide from agglomerating and improve the dispersion uniformity of the nano aluminum hydroxide in the flame retardant layer, thereby significantly improving the oxygen index and tensile strength of the flame retardant layer. DETAILED DESCRIPTION

[0036] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In the following embodiments and comparative examples, unless otherwise specified, the model of polyethylene is DFDA-7042; the model of acetic acid-vinyl acetate copolymer is EVA-7A50H; the model of hydroxyethyl cellulose is QP-52000H; the model of carboxymethyl cellulose is CLHG-005; the model of cellulose acetate is CA-398-3; the particle size of nano aluminum hydroxide is 50nm; the raw material of the insulating layer is cross-linked polyethylene, model LS4201S; the raw material of the sheath layer is polyvinyl chloride, model EP7060; and the conductor is pure copper.

[0038] Example 1

[0039] A method for preparing a medium voltage flame retardant cable comprises the following steps:

[0040] S1. By weight, 100 parts of polyethylene, 20 parts of acetic acid-vinyl acetate copolymer, 40 parts of modified nano aluminum hydroxide, 2 parts of antioxidant 1076, and 1 part of calcium stearate are mixed, extruded, and pelletized to obtain a flame retardant layer masterbatch;

[0041] Among them, during extrusion, the temperature of zone 1 is 100°C, the temperature of zone 2 is 150°C, and the temperature of zone 3 is 120°C;

[0042] The preparation method of modified nano aluminum hydroxide comprises the following steps: dissolving carboxymethyl cellulose in N,N-dimethylformamide, adding nano aluminum hydroxide, dispersing evenly, and drying to obtain modified nano aluminum hydroxide;

[0043] The weight ratio of carboxymethyl cellulose to nano-aluminum hydroxide is 1:30, and the weight ratio of carboxymethyl cellulose to N,N-dimethylformamide is 1:60;

[0044] S2. From the inside to the outside, in the order of insulation layer, flame retardant layer and sheath layer, the raw material of the insulation layer, the masterbatch of the flame retardant layer and the raw material of the sheath layer are sequentially extruded on the surface of the conductor to obtain a medium voltage flame retardant cable.

[0045] Example 2

[0046] A method for preparing a medium voltage flame retardant cable comprises the following steps:

[0047] S1. By weight, 100 parts of polyethylene, 30 parts of acetic acid-vinyl acetate copolymer, 60 parts of modified nano aluminum hydroxide, 4 parts of antioxidant 1076, and 3 parts of calcium stearate are mixed, extruded, and pelletized to obtain a flame retardant layer masterbatch;

[0048] Among them, during extrusion, the temperature of zone 1 is 100°C, the temperature of zone 2 is 150°C, and the temperature of zone 3 is 120°C;

[0049] The preparation method of modified nano aluminum hydroxide comprises the following steps: dissolving hydroxyethyl cellulose in N,N-dimethylformamide, adding nano aluminum hydroxide, dispersing evenly, and drying to obtain modified nano aluminum hydroxide;

[0050] The weight ratio of hydroxyethyl cellulose to nano-aluminum hydroxide is 5:30, and the weight ratio of hydroxyethyl cellulose to N,N-dimethylformamide is 1:60;

[0051] S2. From the inside to the outside, in the order of insulation layer, flame retardant layer and sheath layer, the raw material of the insulation layer, the masterbatch of the flame retardant layer and the raw material of the sheath layer are sequentially extruded on the surface of the conductor to obtain a medium voltage flame retardant cable.

[0052] Example 3

[0053] The only difference between this embodiment and embodiment 2 is that, in this embodiment, hydroxyethyl cellulose is replaced with an equal amount of cellulose acetate when preparing modified nano-aluminum hydroxide.

[0054] Example 4

[0055] The only difference between this embodiment and embodiment 2 is that, in the preparation of modified nano-aluminum hydroxide in this embodiment, hydroxyethyl cellulose is replaced by a mixture of equal amounts of cellulose acetate and hydroxyethyl cellulose in a weight ratio of 1:9.

[0056] Example 5

[0057] The only difference between this embodiment and embodiment 4 is that, in this embodiment, when preparing modified nano aluminum hydroxide, the weight ratio of cellulose acetate to hydroxyethyl cellulose is 9:1.

[0058] Example 6

[0059] The only difference between this embodiment and embodiment 4 is that, in this embodiment, when preparing modified nano aluminum hydroxide, the weight ratio of cellulose acetate to hydroxyethyl cellulose is 1:4.

[0060] Example 7

[0061] The only difference between this embodiment and embodiment 4 is that, in this embodiment, when preparing modified nano aluminum hydroxide, the weight ratio of cellulose acetate to hydroxyethyl cellulose is 1:1.

[0062] Example 8

[0063] The only difference between this embodiment and embodiment 4 is that, in this embodiment, when preparing modified nano aluminum hydroxide, the weight ratio of cellulose acetate to hydroxyethyl cellulose is 4:1.

[0064] Example 9

[0065] The difference between this embodiment and embodiment 8 is that in this embodiment, the preparation method of modified nano aluminum hydroxide comprises the following steps: dissolving potassium cetyl phosphate, hydroxyethyl cellulose and cellulose acetate in N,N-dimethylformamide, adding nano aluminum hydroxide, dispersing evenly, and drying to obtain modified nano aluminum hydroxide;

[0066] The weight ratio of the sum of hydroxyethyl cellulose and cellulose acetate to nano aluminum hydroxide is 5:30, the weight ratio of cellulose acetate to hydroxyethyl cellulose is 4:1, the weight ratio of potassium cetyl phosphate to nano aluminum hydroxide is 1:60, and the weight ratio of the sum of hydroxyethyl cellulose and cellulose acetate to N,N-dimethylformamide is 1:60.

[0067] Example 10

[0068] The only difference between this embodiment and embodiment 9 is that, in this embodiment, when preparing modified nano aluminum hydroxide, the weight ratio of potassium cetyl phosphate to nano aluminum hydroxide is 5:60.

[0069] Comparative Example 1

[0070] The only difference between this comparative example and Example 1 is that in this comparative example, the modified nano aluminum hydroxide is replaced by an equal amount of nano aluminum hydroxide.

[0071] The flame retardant layers of the medium voltage flame retardant cables prepared in Examples 1 to 10 and Comparative Example 1 were subjected to the following performance tests:

[0072] ① Oxygen index: refer to GB / T 2406.2-2009 "Determination of combustion behavior of plastics by oxygen index method Part 2: Room temperature test" to test oxygen index, where the sample type is Ⅰ, the ignition method is A, and the average of the results of 3 samples in each group is taken as the final result, and the result is retained to 1 decimal place;

[0073] ②Tensile strength: The tensile strength was tested according to GB / T 1040.1-2018 “Determination of tensile properties of plastics Part 1: General principles”, where the experimental speed was 20 mm / min, and the average result of 3 specimens in each group was taken as the final result, and the result was retained to 1 decimal place.

[0074] The test results are shown in Table 1 below.

[0075] Table 1 Oxygen index and tensile strength test results

[0076]

[0077] Comparison between Example 1 and Comparative Example 1 shows that the oxygen index and tensile strength of the flame retardant layer can be significantly improved by modifying the nano-aluminum hydroxide by means of cellulose derivatives.

[0078] Comparison between Examples 2 to 3 and Examples 4 to 8 shows that when the cellulose derivative includes cellulose ether and cellulose ester, it helps to further improve the oxygen index and tensile strength of the flame retardant layer. Comparison between Examples 4 to 5 and Examples 6 to 8 shows that when the weight ratio of cellulose ether to cellulose ester is 1:4 to 4:1, it helps to further improve the oxygen index and tensile strength of the flame retardant layer. Comparison between Example 8 and Examples 6 to 7 shows that when the weight of cellulose ester is greater than the weight of cellulose ether, it helps to further improve the oxygen index and tensile strength of the flame retardant layer.

[0079] Comparison between Example 8 and Examples 9-10 shows that when the raw material of the modified nano-aluminum hydroxide also includes potassium cetyl alcohol phosphate, the oxygen index and tensile strength of the flame retardant layer can be further improved.

[0080] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A medium voltage flame retardant cable, comprising a conductor, an insulating layer, a flame retardant layer and a sheath layer arranged in sequence from the inside to the outside, characterized in that: The raw materials of the flame retardant layer include the following components in parts by weight: 100 parts of polyethylene, 20-30 parts of acetic acid-vinyl acetate copolymer, 40-60 parts of modified nano aluminum hydroxide, 2-4 parts of antioxidant, and 1-3 parts of lubricant; The raw materials of the modified nano aluminum hydroxide include cellulose derivatives and nano aluminum hydroxide; The weight ratio of the cellulose derivative to the nano-aluminum hydroxide is 1 to 5:30; The cellulose derivatives include cellulose ethers and cellulose esters; The weight ratio of the cellulose ether to the cellulose ester is 1:4 to 4:1; The cellulose ether includes one of hydroxyethyl cellulose and carboxymethyl cellulose; The cellulose ester includes one of cellulose acetate and cellulose acetate butyrate; The preparation method of the modified nano aluminum hydroxide comprises the following steps: dissolving a cellulose derivative in N,N-dimethylformamide, adding nano aluminum hydroxide, dispersing evenly, and drying to obtain the modified nano aluminum hydroxide.

2. A medium voltage flame retardant cable according to claim 1, characterized in that: The weight of the cellulose ester is greater than the weight of the cellulose ether.

3. A medium voltage flame retardant cable according to claim 1, characterized in that: The raw materials of the modified nano aluminum hydroxide also include potassium cetyl phosphate; The weight ratio of the potassium cetyl phosphate to the nano aluminum hydroxide is 1-5:

60.

4. A medium voltage flame retardant cable according to claim 1, characterized in that: The antioxidant includes one or more of antioxidant 1076, antioxidant 168, and antioxidant 300; and / or The lubricant includes one or more of stearic acid, calcium stearate, and solid paraffin.

5. A medium voltage flame retardant cable according to claim 1, characterized in that: The conductor comprises one of a copper conductor and an aluminum conductor; and / or The material of the insulating layer includes one of cross-linked polyethylene, polyethylene and polypropylene; and / or The material of the sheath layer includes one of polyvinyl chloride and polyethylene.

6. The method for preparing a medium voltage flame-retardant cable according to claim 1, characterized in that: The following steps are involved: S1, mixing, extruding and pelletizing the raw materials of the flame retardant layer to obtain a masterbatch of the flame retardant layer; S2. From the inside to the outside, in the order of the insulating layer, the flame retardant layer masterbatch and the sheath layer, the raw material of the insulating layer, the flame retardant layer masterbatch and the raw material of the sheath layer are sequentially extruded on the surface of the conductor to obtain a medium voltage flame retardant cable.

7. The method for preparing a medium voltage flame-retardant cable according to claim 6, characterized in that: In step S1, the temperature during extrusion is 100-150°C.

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