Halogen-free low-voltage cable

Abstract

The invention discloses a halogen-free low-voltage cable, and belongs to the technical field of low-voltage cables. The cable prepared by the invention sequentially comprises a conductor, an insulating layer, a shielding layer and an outer sheath from inside to outside, wherein the outer sheath comprises the following raw materials in parts by weight: 66-78 parts of ethylene propylene diene monomer, 31-45 parts of natural rubber, 7-17 parts of a halogen-free flame retardant, 6-12 parts of an antioxidant, 5-7 parts of zinc oxide, 4-8 parts of a lubricant, 3-4 parts of sulfur and 0.6-1.2 parts of a vulcanization accelerator. The ethylene propylene diene monomer and the natural rubber are used as matrixes, so that the cable is endowed with excellent impact resistance and aging resistance; the antioxidant can improve the oxidation aging resistance of the cable; wherein the halogen-free flame retardant significantly improves the flame retardance, smoke suppression, impact resistance and certain aging resistance of the cable, and the performance is stable; in conclusion, the prepared cable has important application value in the technical field of low-voltage cables.

Description

Technical Field

[0001] The present invention belongs to the technical field of low-voltage cables, and in particular, relates to a halogen-free low-voltage cable. Background Art

[0002] With the rapid development of modern industry and technology, the demand for power transmission and signal transmission is growing. As an important carrier of power and information transmission, the performance and safety of cables are directly related to the stable operation of the entire system. Among many types of cables, low-voltage cables have attracted much attention due to their wide application in construction, transportation, communications, industrial automation and other fields. However, some problems exposed by traditional low-voltage cables during use have gradually attracted people's attention.

[0003] First, traditional low-voltage cables usually use halogen-containing materials (such as polyvinyl chloride PVC) as insulation or sheath materials. Although this material has good electrical insulation and mechanical strength, it will release a large amount of toxic gases, such as hydrogen chloride, when burned. These gases will cause serious harm to human health and will corrode the surrounding equipment and environment. In addition, the combustion of halogen-containing materials will also produce a lot of thick smoke, reducing visibility at the fire scene and increasing the difficulty of rescue. Therefore, in the pursuit of green and sustainable development today, the use of halogen-containing materials can no longer meet the environmental protection and safety requirements of modern society.

[0004] Secondly, low-voltage cables often face complex environmental conditions in practical applications. Traditional halogen-containing cables are prone to aging, cracking, and even failure under complex environmental conditions. In addition, during use, the cables have defects such as low strength and poor impact resistance, which shortens the service life of the cables and affects the normal operation of the entire system. In summary, the research and development of halogen-free low-voltage cables is not only an inevitable choice to meet current technological challenges, but also a key step in promoting the transformation of the cable industry towards green and intelligent. Therefore, it is urgent to invent a halogen-free low-voltage cable that is flame-retardant, impact-resistant, and aging-resistant to meet higher demands in the field of low-voltage cable technology. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a halogen-free low-voltage cable.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A halogen-free low-voltage cable comprises, from inside to outside, a conductor, an insulating layer, a shielding layer and an outer sheath.

[0008] Furthermore, the conductor is formed by twisting a plurality of thin copper wires.

[0009] Furthermore, the material of the insulating layer is thermoplastic polyester elastomer.

[0010] Furthermore, the material of the shielding layer is an aluminum-plastic composite tape.

[0011] Furthermore, the material of the outer sheath includes the following raw materials in parts by weight: 66-78 parts of EPDM rubber, 31-45 parts of natural rubber, 7-17 parts of halogen-free flame retardant, 6-12 parts of antioxidant, 5-7 parts of zinc oxide, 4-8 parts of lubricant, 3-4 parts of sulfur, and 0.6-1.2 parts of vulcanization accelerator.

[0012] Furthermore, the lubricant is one of zinc stearate, white paraffin, stearic acid and polyethylene wax.

[0013] Furthermore, the vulcanization accelerator is one of tetramethylthiuram disulfide, zinc diethyldithiocarbamate and 2-mercaptobenzothiazole.

[0014] Furthermore, the antioxidant is prepared by compounding antioxidant 1010 and antioxidant 168 at a mass ratio of 5:1.

[0015] The outer sheath prepared by the invention uses EPDM rubber and natural rubber as a matrix, the EPDM rubber has excellent weather resistance, and the natural rubber has excellent elasticity and flexibility, so the outer sheath material can be endowed with excellent impact resistance and aging resistance; the added antioxidants are hindered phenol antioxidants and phosphite auxiliary antioxidants, both of which can greatly enhance the anti-oxidation and aging performance of the outer sheath material; the addition of zinc oxide can increase the crosslinking density of the finished product and promote vulcanization; the vulcanization accelerator shortens the vulcanization time, lowers the vulcanization temperature, and reduces the amount of vulcanizer used.

[0016] Furthermore, the halogen-free flame retardant is prepared by the following steps:

[0017] Step 1, add tris(hydroxymethyl)aminomethane hydrochloride, triethylamine and N,N-dimethylformamide into a three-necked flask equipped with a magnetic stirrer and a thermometer, place the system in an ice bath at 2°C, stir evenly, then slowly drop phosphorus oxychloride, control the system temperature not to exceed 20°C during the dropwise addition, heat the system until the temperature reaches 105°C, and keep the temperature for 6 hours. After the reaction is completed, remove the solvent by vacuum filtration, wash the filter cake with anhydrous ethanol for several times, dry in an oven, and grind into powder to obtain an intermediate product 1;

[0018] The three hydroxyl groups on tris(hydroxymethyl)aminomethane hydrochloride react with the three chlorine groups on phosphorus oxychloride, and triethylamine removes the hydrogen chloride generated by the reaction to obtain intermediate product 1; the structure of intermediate product 1 is shown below:

[0019]

[0020] Step 2, add cyanuric chloride and toluene to a three-necked flask equipped with a magnetic stirrer and a thermometer, pre-cool and stir for 20 minutes in an ice-water bath at 2°C, then add the intermediate product 1, and slowly dropwise add sodium hydroxide solution through a constant pressure funnel, keeping the temperature at 5°C during the dropping process. After the dropping is completed, keep the temperature for 3 hours. After the reaction is completed, filter, remove the solvent by distillation under reduced pressure, wash with chloroform for several times, and vacuum dry to obtain the intermediate product 2;

[0021] Cyanuric chloride undergoes a nucleophilic substitution reaction with the intermediate product 2, and the sodium hydroxide solution acts as an acid-binding agent to promote the reaction. By adjusting the molar ratio of cyanuric chloride to the intermediate product 2 to close to 1:1 (slightly excessive cyanuric chloride), it can be ensured that only one chlorine group in the cyanuric chloride molecule undergoes a substitution reaction to obtain the intermediate product 2. The specific reaction process is as follows:

[0022]

[0023] Step 3, add 1,3-bis(aminopropyl)tetramethyldisiloxane, intermediate 2 and xylene into a three-necked flask equipped with a magnetic stirrer and a thermometer, introduce nitrogen as a protective gas, heat the system to 50°C, and then add sodium hydroxide solution dropwise using a constant pressure funnel. After the addition is completed, heat the system to 110°C and keep the temperature for 10 hours. After the reaction is completed, cool the system to room temperature, wash the system with distilled water, ethanol and acetone for multiple times, and dry the system in vacuo to obtain a halogen-free flame retardant.

[0024] 1,3-Bis(aminopropyl)tetramethyldisiloxane reacts with the intermediate product 2, and sodium hydroxide solution is used as an acid binding agent to promote the reaction to obtain a halogen-free flame retardant. The specific reaction process is as follows:

[0025]

[0026] Furthermore, in step 1, the ratio of tris(hydroxymethyl)aminomethane hydrochloride, triethylamine, N,N-dimethylformamide, and phosphorus oxychloride is 15.9 g:50 mL:100 mL:15.2 g.

[0027] Furthermore, in step 2, the ratio of cyanuric chloride, toluene, intermediate product 1, and sodium hydroxide solution is 20.3 g:100 mL:16.5 g:20 mL.

[0028] Furthermore, in step 3, the ratio of the amount of 1,3-bis(aminopropyl)tetramethyldisiloxane, intermediate 2, xylene, and sodium hydroxide solution is 24.8 g:31.1 g:200 mL:50 mL.

[0029] The prepared halogen-free flame retardant is a macromolecular flame retardant. Compared with the small molecule flame retardants on the market, its performance is more stable and it is not easy to migrate in the rubber matrix. In addition, the halogen-free flame retardant contains a variety of flame retardant ingredients, among which the caged phosphonate structure forms a three-dimensional cross-linked network through strong covalent bonds, which significantly increases the thermal decomposition temperature, and decomposes at high temperature to generate phosphoric acid and polyphosphoric acid to promote carbonization to form a heat-insulating and oxygen-isolating carbon layer, while releasing PO· free radicals to capture active species in the combustion chain reaction and dilute the combustible gas, thereby achieving the effects of flame retardancy and smoke suppression. In addition, the triazine structure in the molecule The structure decomposes at high temperature to generate nitrogen-containing free radicals, which can capture active free radicals in the gas phase and interrupt combustion. At the same time, it promotes carbonization in the condensed phase to form a heat-insulating and oxygen-isolating carbon layer, and releases ammonia, nitrogen and other diluent combustible gases and suppresses smoke, thereby achieving the effects of flame retardancy and smoke suppression, and plays a synergistic role with the cage-like phosphonate structure, significantly improving the flame retardant properties of the matrix. Finally, the Si-O bond contained in the molecule has a long bond length, a large bond angle, and a low rotational energy barrier, good flexibility, and can improve the impact resistance of the matrix. Not only that, the siloxane group also has certain anti-aging properties.

[0030] Beneficial effects of the present invention:

[0031] The cable made by the present invention comprises, from inside to outside, a conductor, an insulating layer, a shielding layer and an outer sheath;

[0032] 1. The outer sheath is made of EPDM rubber and natural rubber as the matrix, which gives the cable excellent impact resistance and aging resistance;

[0033] 2. The antioxidant added to the outer sheath can play a synergistic effect and improve the anti-oxidation and aging performance of the cable;

[0034] 3. The self-made halogen-free flame retardant is added to the outer sheath, which significantly improves the flame retardancy, smoke suppression, impact resistance and certain aging resistance of the cable, and the performance is stable;

[0035] In summary, the cable produced by the present invention has stable and efficient flame retardant, smoke suppression, impact resistance and aging resistance properties, and has important application value in the field of low-voltage cable technology. 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] Embodiment 1

[0038] Preparation of halogen-free flame retardants:

[0039] Step 1, add 15.9g tris(hydroxymethyl)aminomethane hydrochloride, 50mL triethylamine and 100mL N,N-dimethylformamide into a three-necked flask equipped with a magnetic stirrer and a thermometer, place the system in an ice bath at 2°C, stir evenly, then slowly drop 15.2g phosphorus oxychloride, control the system temperature not to exceed 20°C during the dropwise addition, heat the system until the temperature reaches 105°C, keep the temperature for 6h, after the reaction is completed, remove the solvent by vacuum filtration, wash the filter cake with anhydrous ethanol for several times, dry in an oven, and grind into powder to obtain intermediate 1;

[0040] Step 2, 20.3g of cyanuric chloride and 100mL of toluene were added to a three-necked flask equipped with a magnetic stirrer and a thermometer, pre-cooled and stirred in an ice-water bath at 2°C for 20min, then 16.5g of the intermediate product 1 was added, and 20mL of sodium hydroxide solution (mass fraction 8%) was slowly added dropwise through a constant pressure funnel, and the temperature was kept at 5°C during the addition process. After the addition was completed, the reaction was kept warm for 3h. After the reaction was completed, the mixture was filtered, the solvent was removed by distillation under reduced pressure, the mixture was washed with chloroform for several times, and vacuum dried to obtain the intermediate product 2;

[0041] Step 3, add 24.8g1,3-bis(aminopropyl)tetramethyldisiloxane, 31.1g intermediate product 2 and 200mL xylene into a three-necked flask equipped with a magnetic stirrer and a thermometer, introduce nitrogen as a protective gas, heat the system to 50°C, and then add 50mL of sodium hydroxide solution (mass fraction 8%) dropwise using a constant pressure funnel. After the addition is complete, heat the mixture to 110°C and keep the reaction for 10h. After the reaction is complete, cool the mixture to room temperature, wash it with distilled water, ethanol and acetone several times in turn, and dry it in vacuo to obtain a halogen-free flame retardant.

[0042] Embodiment 2

[0043] Preparation of halogen-free flame retardants:

[0044] Step 1, add 31.8g tris(hydroxymethyl)aminomethane hydrochloride, 100mL triethylamine and 200mL N,N-dimethylformamide into a three-necked flask equipped with a magnetic stirrer and a thermometer, place the system in an ice bath at 2°C, stir evenly, then slowly drop 30.4g phosphorus oxychloride, control the system temperature not to exceed 20°C during the dropwise addition, heat the system until the temperature reaches 105°C, keep the temperature for 6h, after the reaction is completed, remove the solvent by vacuum filtration, wash the filter cake with anhydrous ethanol for several times, dry in an oven, and grind into powder to obtain intermediate 1;

[0045] Step 2, 40.6g of cyanuric chloride and 200mL of toluene were added to a three-necked flask equipped with a magnetic stirrer and a thermometer, pre-cooled and stirred in an ice-water bath at 2°C for 20min, then 33.0g of the intermediate product 1 was added, and 40mL of sodium hydroxide solution (mass fraction 8%) was slowly added dropwise through a constant pressure funnel, and the temperature was kept at 5°C during the addition process. After the addition was completed, the reaction was kept warm for 3h. After the reaction was completed, the mixture was filtered, the solvent was removed by distillation under reduced pressure, the mixture was washed with chloroform for several times, and vacuum dried to obtain the intermediate product 2;

[0046] Step 3, add 49.6g1,3-bis(aminopropyl)tetramethyldisiloxane, 62.2g intermediate product 2 and 400mL xylene into a three-necked flask equipped with a magnetic stirrer and a thermometer, introduce nitrogen as a protective gas, heat the system to 50°C, and then add 100mL of sodium hydroxide solution (mass fraction 8%) dropwise using a constant pressure funnel. After the addition is complete, heat the mixture to 110°C and keep the reaction for 10h. After the reaction is complete, cool the mixture to room temperature, wash it with distilled water, ethanol and acetone several times in turn, and dry it in vacuo to obtain a halogen-free flame retardant.

[0047] Embodiment 3

[0048] Materials for making the outer sheath:

[0049] 66g of EPDM rubber and 31g of natural rubber were added to an open mill for the first mixing. After the mixing was completed, 7g of the halogen-free flame retardant prepared in Example 1, 6g of antioxidant (5g of antioxidant 1010 and 1g of antioxidant 168), 5g of zinc oxide, 4g of zinc stearate, 3g of sulfur and 0.6g of tetramethylthiuram disulfide were added for the second mixing. After the mixing was completed, vulcanization was carried out. After the vulcanization was completed, the material of the outer sheath was obtained.

[0050] Embodiment 4

[0051] Materials for making the outer sheath:

[0052] 72g of EPDM rubber and 38g of natural rubber were added to an open mill for the first mixing. After the mixing was completed, 12g of the halogen-free flame retardant prepared in Example 2, 9g of antioxidant (7.5g of antioxidant 1010 and 1.5g of antioxidant 168), 6g of zinc oxide, 6g of polyethylene wax, 4g of sulfur and 0.8g of 2-mercaptobenzothiazole were added for the second mixing. After the mixing was completed, vulcanization was carried out. After the vulcanization was completed, the material of the outer sheath was obtained.

[0053] Embodiment 5

[0054] Materials for making the outer sheath:

[0055] 78g of EPDM rubber and 45g of natural rubber were added to an open mill for the first mixing. After the mixing was completed, 17g of the halogen-free flame retardant prepared in Example 2, 12g of antioxidant (prepared by compounding 10g of antioxidant 1010 and 2g of antioxidant 168), 7g of zinc oxide, 8g of polyethylene wax, 3-4g of sulfur and 1.2g of 2-mercaptobenzothiazole were added for the second mixing. After the mixing was completed, vulcanization was carried out. After the vulcanization was completed, the material of the outer sheath was obtained.

[0056] Embodiment 6

[0057] A plurality of thin copper wires are twisted to form a conductor, a thermoplastic polyester elastomer is extruded on the surface of the conductor to form an insulating layer, and then an aluminum-plastic composite tape is wrapped on the surface of the insulating layer to form a shielding layer. Subsequently, 78g of EPDM rubber and 45g of natural rubber are added to an open mill for the first mixing. After the mixing is completed, 17g of the halogen-free flame retardant prepared in Example 2, 12g of antioxidant (prepared by compounding 10g of antioxidant 1010 and 2g of antioxidant 168), 7g of zinc oxide, 8g of polyethylene wax, 3-4g of sulfur and 1.2g of 2-mercaptobenzothiazole are added for the second mixing. After the mixing is completed, it is extruded and coated on the surface of the shielding layer, and finally vulcanized to obtain a halogen-free low-voltage cable.

[0058] Comparative Example 1

[0059] The halogen-free flame retardant in Example 5 was replaced by a commercially available halogen-containing flame retardant of equal quality, and the remaining steps were the same as those in Example 5 to obtain the material.

[0060] Comparative Example 2

[0061] Use commercially available halogen-free flame-retardant rubber cable materials.

[0062] Embodiments 3, 4, 5 and comparative examples 1 and 2 were made into corresponding shapes according to different test standards and subjected to the following performance tests:

[0063] The elongation at break is determined using the national standard GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber";

[0064] The national standard GB / T 16585 "Artificial weathering aging (fluorescent ultraviolet lamp) test method for vulcanized rubber" was used to determine the elongation at break of the aged sample (GB / T 528-2009), and the elongation at break retention rate was calculated; elongation at break retention rate = elongation at break after test / elongation at break before test × 100%;

[0065] The smoke density is measured using the national standard GB / T 8323.2-2008;

[0066] The limiting oxygen index of the sample was measured according to the national standard GB / T 10707-2008 "Determination of Rubber Combustion Performance", and then the limiting oxygen index of Examples 3, 4, 5 and Comparative Examples 1 and 2 was measured again after being stored at room temperature for 100 days; and the limiting oxygen index retention rate was calculated; limiting oxygen index retention rate = limiting oxygen index after test / limiting oxygen index before test × 100%;

[0067] The measured results are shown in the following table:

[0068]

[0069] It can be seen from the above table that the flame retardancy, smoke suppression, impact resistance and aging resistance of the cable prepared in the embodiment of the present invention are higher than those of the control example, and the performance is stable for a long time. Therefore, the present invention has important application value in the field of low-voltage cable technology.

[0070] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation 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 one or more embodiments or examples in a suitable manner.

[0071] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A halogen-free low-voltage cable, comprising, from inside to outside, a conductor, an insulating layer, a shielding layer and an outer sheath, characterized in that: The material of the outer sheath includes the following raw materials in parts by weight: 66-78 parts of EPDM rubber, 31-45 parts of natural rubber, 7-17 parts of halogen-free flame retardant, 6-12 parts of antioxidant, 5-7 parts of zinc oxide, 4-8 parts of lubricant, 3-4 parts of sulfur, and 0.6-1.2 parts of vulcanization accelerator.

2. A halogen-free low-voltage cable according to claim 1, characterized in that: The halogen-free flame retardant is prepared by the following steps: Step 1, add tris(hydroxymethyl)aminomethane hydrochloride, triethylamine and N,N-dimethylformamide into a flask, place the system in an ice bath at 2°C, stir evenly, then drop phosphorus oxychloride, after the dropwise addition is complete, heat the system until the temperature reaches 105°C, keep the temperature for reaction for 6 hours, after the reaction is completed, reduce pressure and filter, wash, dry, and grind to obtain intermediate 1; Step 2, add cyanuric chloride and toluene into a flask, stir for 20 minutes in an ice-water bath at 2°C, then add intermediate product 1, and dropwise add sodium hydroxide solution, keeping the temperature at 5°C during the dropping process. After the dropping is completed, keep the temperature for 3 hours. After the reaction is completed, filter, distill under reduced pressure, wash, and dry to obtain intermediate product 2; Step 3, add 1,3-bis(aminopropyl)tetramethyldisiloxane, intermediate 2 and xylene into a flask, introduce nitrogen, heat up to the system temperature to 50°C, then add sodium hydroxide solution dropwise, after the addition is complete, heat up to 110°C, keep warm for 10 hours, and after the reaction is complete, cool to room temperature, wash, and dry to obtain a halogen-free flame retardant.

3. A halogen-free low-voltage cable according to claim 2, characterized in that: In step 1, the ratio of tris(hydroxymethyl)aminomethane hydrochloride, triethylamine, N,N-dimethylformamide and phosphorus oxychloride is 15.9 g:50 mL:100 mL:15.2 g.

4. A halogen-free low-voltage cable according to claim 2, characterized in that: In step 2, the ratio of cyanuric chloride, toluene, intermediate product 1 and sodium hydroxide solution is 20.3 g:100 mL:16.5 g:20 mL.

5. The halogen-free low-voltage cable according to claim 2, characterized in that: In step 3, the ratio of the amount of 1,3-bis(aminopropyl)tetramethyldisiloxane, intermediate 2, xylene, and sodium hydroxide solution is 24.8 g:31.1 g:200 mL:50 mL.

6. The halogen-free low-voltage cable according to claim 1, characterized in that: The lubricant is one of zinc stearate, white paraffin, stearic acid and polyethylene wax.

7. The halogen-free low-voltage cable according to claim 1, characterized in that: The vulcanization accelerator is one of tetramethylthiuram disulfide, zinc diethyldithiocarbamate and 2-mercaptobenzothiazole.

8. The halogen-free low-voltage cable according to claim 1, characterized in that: The antioxidant is prepared by compounding antioxidant 1010 and antioxidant 168 at a mass ratio of 5:1.

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