Low-smoke halogen-free flame-retardant cable material and preparation method thereof

Abstract

The invention relates to the technical field of cable materials, and provides a low-smoke halogen-free flame-retardant cable material and a preparation method thereof.The cable material is prepared from, by weight, 16-20 parts of ethylene-vinyl acetate copolymer, 4-6 parts of polyolefin elastomer, 6-8 parts of polyethylene, 5-7 parts of compatilizer, 60-70 parts of composite flame retardant and 1-2 parts of antioxidant; the composite flame retardant is prepared from sepiolite, N, N '-diacryloylethylenediamine and an inorganic flame retardant. According to the technical scheme, the problems of poor flame retardance and mechanical property of the cable material in the prior art are solved.

Description

Technical Field

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

[0002] With the rapid development of modern society, cables are increasingly used in various fields, from power transmission to communications, rail transit, construction and other fields, cables play a vital role. Traditional cable materials usually use halogen-containing polymers, and halogen-containing cable materials will release a large amount of thick smoke and toxic and harmful hydrogen halide gas when burning. These smoke and gases will not only pose a serious threat to people's life safety, but also pollute the environment. When a fire occurs, thick smoke will hinder people's sight and affect the evacuation and rescue work; and hydrogen halide gas is corrosive and will cause damage to equipment and buildings. With the continuous improvement of people's requirements for safety and environmental protection, low-smoke halogen-free cable materials have gradually become the development trend of the cable industry. Low-smoke halogen-free cable materials produce less smoke when burning, and do not release toxic and harmful gases such as hydrogen halide, and have good safety and environmental protection performance. In order to achieve the characteristics of low smoke and halogen-free, a large amount of inorganic flame retardants are often added to the cable materials. Although these flame retardants can effectively reduce the combustion performance of the material, they will also reduce the toughness and elasticity of the material, thereby affecting the mechanical properties of the cable material. Therefore, it is necessary to prepare a low-smoke halogen-free cable material with high flame retardancy and good mechanical properties to meet its application in various environments. Summary of the invention

[0003] The invention provides a low-smoke halogen-free flame-retardant cable material and a preparation method thereof, which solves the problem of poor flame retardancy and mechanical properties of the cable material in the related art.

[0004] The technical solution of the present invention is as follows: The invention provides a low-smoke halogen-free flame-retardant cable material, comprising the following raw materials in parts by weight: 16-20 parts of ethylene-vinyl acetate copolymer, 4-6 parts of polyolefin elastomer, 6-8 parts of polyethylene, 5-7 parts of compatibilizer, 60-70 parts of composite flame retardant, and 1-2 parts of antioxidant; the composite flame retardant comprises sepiolite, N,N'-diacrylamide, and an inorganic flame retardant.

[0005] As a further technical solution, the inorganic flame retardant includes one or both of aluminum hydroxide and magnesium hydroxide.

[0006] As a further technical solution, when the inorganic flame retardant is aluminum hydroxide and magnesium hydroxide, the mass ratio of aluminum hydroxide to magnesium hydroxide is 3:1.

[0007] As a further technical solution, the sepiolite is an acid-activated active sepiolite.

[0008] In the present invention, the activity of the sepiolite is increased by activating the sepiolite with acid, thereby further improving the flame retardancy and mechanical properties of the cable material.

[0009] As a further technical solution, the method for preparing the activated sepiolite comprises the following steps: adding the sepiolite into an acidic aqueous solution for activation, and obtaining the activated sepiolite after drying.

[0010] As a further technical solution, the acidic aqueous solution is a boric acid aqueous solution.

[0011] In the present invention, the flame retardancy of the cable material is further improved by activating the sepiolite with a boric acid aqueous solution.

[0012] As a further technical solution, the mass concentration of the acidic aqueous solution is 5%.

[0013] As a further technical solution, the activation temperature is 60° C. and the activation time is 10 h.

[0014] As a further technical solution, the mass ratio of the active sepiolite, the inorganic flame retardant and N,N'-diacrylamide is 0.5:3:0.1-0.3.

[0015] As a further technical solution, the preparation method of the composite flame retardant includes the following steps: adding an inorganic flame retardant to methanol, adding N,N'-diacrylamide to perform a first modification, then adding active sepiolite to perform a second modification, and obtaining the composite flame retardant after drying.

[0016] In the present invention, the inorganic flame retardant is first modified by N,N'-diacrylamide and then secondly modified with active sepiolite, thereby further improving the flame retardancy and mechanical properties of the cable material.

[0017] As a further technical solution, the temperature of the first modification and the second modification are independently 40-50° C., and the time of the first modification and the second modification are independently 2-3 hours.

[0018] As a further technical solution, the compatibilizer includes one or two of PE-g-MAH and POE-g-GMA.

[0019] As a further technical solution, the antioxidant includes one or more of antioxidant 168, antioxidant 1010, and antioxidant 2246.

[0020] The present invention also provides a method for preparing the low-smoke halogen-free flame-retardant cable material, comprising the following steps: mixing the raw materials of various components, and then mixing and extruding to obtain the low-smoke halogen-free cable material.

[0021] The working principle and beneficial effects of the present invention are: In the present invention, sepiolite has a unique porous structure and can form a physical barrier layer during the combustion process to delay the transfer of heat and combustible gas. The addition of a composite flame retardant consisting of active sepiolite, N,N'-diacrylamide and an inorganic flame retardant improves the flame retardancy and mechanical properties of the cable material, thereby solving the problem of poor flame retardancy and mechanical properties of the cable material. DETAILED DESCRIPTION

[0022] 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.

[0023] In the following embodiments and comparative examples: Ethylene-vinyl acetate copolymer, brand: V5110J; polyolefin elastomer, brand: 8411; polyethylene, brand: 2426H; POE-g-GMA, brand: SH035, purchased from Dongguan Shenghao Plastic Raw Materials Co., Ltd.; PE-g-MAH, model: XYJ1251, purchased from Dongguan Xingyuan Chemical Co., Ltd.; Sepiolite, particle size: 800 mesh; aluminum hydroxide, particle size: 20 nm; magnesium hydroxide, particle size: 20 nm.

[0024] Example 1 A method for preparing a low-smoke halogen-free flame-retardant cable material comprises the following steps: 16 parts of ethylene-vinyl acetate copolymer, 6 parts of polyolefin elastomer, 6 parts of polyethylene, 5 parts of PE-g-MAH, 60 parts of composite flame retardant and 1 part of antioxidant 168 were mixed, and then mixed and extruded to obtain low-smoke halogen-free cable material.

[0025] The composite flame retardant is prepared by mixing sepiolite in a mass ratio of 0.5:3:0.1, an inorganic flame retardant (aluminum hydroxide and magnesium hydroxide in a mass ratio of 3:1), and N,N'-diacrylamide.

[0026] Example 2 A method for preparing a low-smoke halogen-free flame-retardant cable material comprises the following steps: 18 parts of ethylene-vinyl acetate copolymer, 5 parts of polyolefin elastomer, 7 parts of polyethylene, 6 parts of POE-g-GMA, 65 parts of composite flame retardant and 1 part of antioxidant 1010 were mixed, and then mixed and extruded to obtain low-smoke halogen-free cable material.

[0027] The composite flame retardant is prepared by mixing sepiolite in a mass ratio of 0.5:3:0.2, an inorganic flame retardant (aluminum hydroxide and magnesium hydroxide in a mass ratio of 3:1), and N,N'-diacrylamide.

[0028] Example 3 A method for preparing a low-smoke halogen-free flame-retardant cable material comprises the following steps: 20 parts of ethylene-vinyl acetate copolymer, 4 parts of polyolefin elastomer, 8 parts of polyethylene, 7 parts of POE-g-GMA, 70 parts of composite flame retardant and 2 parts of antioxidant 2246 are mixed, and then the mixture is kneaded and extruded to obtain low-smoke halogen-free cable material.

[0029] The composite flame retardant is prepared by mixing sepiolite, an inorganic flame retardant (aluminum hydroxide and magnesium hydroxide in a mass ratio of 3:1), and N,N'-diacrylamide in a mass ratio of 0.5:3:0.3.

[0030] Example 4 The only difference between this embodiment and embodiment 1 is that the sepiolite is replaced by an equal amount of active sepiolite.

[0031] The preparation method of active sepiolite comprises the following steps: adding 50 g of sepiolite into 400 mL of hydrochloric acid aqueous solution (5 wt %), stirring at 60° C. for 10 h, filtering and drying to obtain the active sepiolite.

[0032] Example 5 The only difference between this embodiment and embodiment 4 is that the hydrochloric acid aqueous solution is replaced by an equal volume of boric acid aqueous solution (5 wt %).

[0033] Example 6 The present embodiment is different from the embodiment 5 only in that the preparation method of the composite flame retardant comprises the following steps: adding 60 g of inorganic flame retardant (aluminum hydroxide and magnesium hydroxide in a mass ratio of 3:1) to 500 mL of methanol, adding 2 g of N,N'-diacrylamide, stirring at 50°C for 3 h, adding 10 g of activated sepiolite, continuing to stir at 50°C for 3 h, and drying to obtain the composite flame retardant.

[0034] Example 7 The present embodiment is different from the embodiment 5 only in that the preparation method of the composite flame retardant comprises the following steps: adding 10 g of active sepiolite to 500 mL of methanol, adding 2 g of N,N'-diacrylamide, stirring at 50°C for 3 h, adding 60 g of inorganic flame retardant (the mass ratio of aluminum hydroxide to magnesium hydroxide is 3:1), continuing to stir at 50°C for 3 h, and obtaining the composite flame retardant after drying.

[0035] Example 8 The present embodiment is different from the embodiment 5 only in that the preparation method of the composite flame retardant comprises the following steps: adding 60 g of inorganic flame retardant (aluminum hydroxide and magnesium hydroxide in a mass ratio of 3:1) to 500 mL of methanol, adding 10 g of active sepiolite, stirring at 50° C. for 3 h, adding 2 g of N,N'-diacrylamide, continuing to stir at 50° C. for 3 h, and obtaining the composite flame retardant after drying.

[0036] Comparative Example 1 The only difference between this comparative example and Example 1 is that the composite flame retardant is a mixture of sepiolite and an inorganic flame retardant (aluminum hydroxide and magnesium hydroxide in a mass ratio of 3:1) in a mass ratio of 0.5:3.

[0037] Comparative Example 2 The only difference between this comparative example and Example 1 is that the composite flame retardant is a mixture of an inorganic flame retardant (aluminum hydroxide and magnesium hydroxide in a mass ratio of 3:1) and N,N'-diacrylamide in a mass ratio of 3:0.1.

[0038] Comparative Example 3 The only difference between this comparative example and Example 1 is that the composite flame retardant is a mixture of sepiolite and N,N'-diacrylamide in a mass ratio of 5:1.

[0039] The flame retardancy and mechanical properties of the cable materials prepared in Examples 1 to 8 and Comparative Examples 1 to 3 were tested respectively, and the specific test methods are as follows: Flame retardancy: The oxygen index of the cable material is tested according to the determination method in GB / T 2406.2-2009 "Determination of combustion behavior of plastics by oxygen index method Part 2: Room temperature test"; Mechanical properties: The tensile strength of the cable material is tested according to the test method in GB / T 1040.3-2006 "Determination of tensile properties of plastics Part 3: Test conditions for films and sheets"; the elongation at break of the cable material is tested according to the test method in GB / T 32129-2015 "Halogen-free low-smoke flame-retardant cable materials for wires and cables"; The test results are shown in Table 1.

[0040] Table 1 Test results of cable material properties of Examples 1 to 8 and Comparative Examples 1 to 3

[0041] Compared with Example 1, no N,N'-diacrylamide was added in Comparative Example 1, no sepiolite was added in Comparative Example 2, and no inorganic flame retardant was added in Comparative Example 3. As a result, the oxygen index, tensile strength and elongation at break of the cable materials prepared in Comparative Examples 1 to 3 were lower than those in Example 1, indicating that the composite flame retardant composed of N,N'-diacrylamide, sepiolite and inorganic flame retardant can improve the flame retardancy, tensile strength and elongation at break of the cable material.

[0042] Compared with Example 1, hydrochloric acid was used to activate the sepiolite in Example 4, and boric acid was used to activate the sepiolite in Example 5. As a result, the oxygen index, tensile strength and elongation at break of the cable materials prepared in Examples 4~5 were higher than those in Example 1, indicating that after activating the sepiolite, the flame retardancy, tensile strength and elongation at break of the cable material can be further improved; comparing Examples 4 and 5, it was found that the oxygen index in Example 5 was higher than that in Example 4, indicating that activating the sepiolite with boric acid can further improve the flame retardancy of the cable material.

[0043] Compared with Example 5, Examples 6 to 8 adjust the modification order of N,N'-diacrylamide, sepiolite, and inorganic flame retardant. As a result, the oxygen index, tensile strength, and elongation at break of the cable material prepared in Example 6 are higher than those of Examples 5, 7, and 8, indicating that when the inorganic flame retardant is modified by N,N'-diacrylamide for the first time and then sepiolite is added for the second modification, the flame retardancy, tensile strength, and elongation at break of the cable material can be further improved.

[0044] The cable material prepared in Example 6 has an elongation at break of up to 223% and a hardness of up to 58 Shore D.

[0045] 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 low-smoke halogen-free flame-retardant cable material, characterized in that: The raw materials include the following components in parts by weight: 16-20 parts of ethylene-vinyl acetate copolymer, 4-6 parts of polyolefin elastomer, 6-8 parts of polyethylene, 5-7 parts of compatibilizer, 60-70 parts of composite flame retardant, and 1-2 parts of antioxidant; the composite flame retardant includes sepiolite, N,N'-diacrylamide, and inorganic flame retardant.

2. The low-smoke halogen-free flame-retardant cable material according to claim 1, characterized in that: The inorganic flame retardant includes one or both of aluminum hydroxide and magnesium hydroxide.

3. The low-smoke halogen-free flame-retardant cable material according to claim 2, characterized in that: When the inorganic flame retardant is aluminum hydroxide and magnesium hydroxide, the mass ratio of aluminum hydroxide to magnesium hydroxide is 3:

1.

4. The low-smoke halogen-free flame-retardant cable material according to claim 1, characterized in that: The sepiolite is an acid-activated active sepiolite.

5. The low-smoke halogen-free flame-retardant cable material according to claim 4, characterized in that: The preparation method of the active sepiolite comprises the following steps: adding the sepiolite into an acidic aqueous solution for activation, and obtaining the active sepiolite after drying.

6. The low-smoke halogen-free flame-retardant cable material according to claim 5, characterized in that: The acidic aqueous solution is a boric acid aqueous solution.

7. The low-smoke halogen-free flame-retardant cable material according to claim 1, characterized in that: The mass ratio of the sepiolite, the inorganic flame retardant and the N,N'-diacrylamide is 0.5:3:0.1-0.

3.

8. The low-smoke halogen-free flame-retardant cable material according to claim 1, characterized in that: The preparation method of the composite flame retardant comprises the following steps: adding an inorganic flame retardant into methanol, adding N,N'-diacrylamide ethylenediamine for a first modification, adding sepiolite for a second modification, and drying to obtain the composite flame retardant.

9. The low-smoke halogen-free flame-retardant cable material according to claim 1, characterized in that: The antioxidant includes one or more of antioxidant 168 , antioxidant 1010 , and antioxidant 2246 .

10. The method for preparing a low-smoke halogen-free flame-retardant cable material according to any one of claims 1 to 9, characterized in that: The following steps are involved: After mixing the raw materials of various components, the low-smoke halogen-free cable material is obtained after internal mixing and extrusion.

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