Flame-retardant fireproof wire and cable and manufacturing process thereof

Abstract

The invention relates to the technical field of electric wires and cables, and discloses a flame-retardant fireproof electric wire and cable and a manufacturing process thereof.The flame-retardant fireproof electric wire and cable sequentially comprises a wire core layer, an inner lining layer and an outer sheath layer from inside to outside, and the outer sheath layer is formed by extruding and wrapping an outer sheath layer material on the outer side of the inner lining layer; the material of the outer sheath layer is prepared by taking high-density polyethylene, linear low-density polyethylene, a compatilizer, an organic-inorganic composite flame retardant and the like as raw materials and carrying out mixing and melt extrusion processes, and the organic-inorganic composite flame retardant is prepared by forming a macromolecular modifier connected by an ester bond in rectorite. The existence of the macromolecular modifier can improve the compatibility between the rectorite and the polyethylene matrix, so that the rectorite efficiently exerts the self-reinforcing effect, the sheath layer shows higher mechanical strength, and the macromolecular modifier can cooperate with the rectorite, so that the fireproof and flame-retardant effects of the outer sheath layer are greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electric wires and cables, and in particular to a flame-retardant and fireproof electric wire and cable and a manufacturing process thereof. Background Art

[0002] Wires and cables, as key carriers for power transmission and signal control, are widely used in construction, transportation, energy, and industrial fields. Currently, wires and cables generally require an outer sheath layer to mechanically protect the conductor. Polymer materials such as polyethylene (PE) have advantages such as high resistivity, strong environmental adaptability, and simple processing. Therefore, the outer sheath layer of wires and cables currently mostly uses polymer materials as the base material. However, polymer materials such as polyethylene are mostly flammable or combustible, and can easily cause fires under the influence of short circuits, overloads, or external fire sources. Furthermore, polyethylene is a thermoplastic material, and during combustion, molten drips will occur, causing the flame to spread and exacerbate the disaster. At the same time, a large amount of smoke will be produced, posing a great threat to the environment and personnel safety. Therefore, the development of flame-retardant and fire-resistant wires and cables has become an urgent need in the field of power safety.

[0003] Currently, cable sheath flame retardant technology primarily relies on chemical flame retardants. Halogenated flame retardants were typically used in the early stages. However, these produce large amounts of corrosive and toxic fumes when burned, leading to their gradual ban. Inorganic hydroxide flame retardants are also available, but these require high filler levels (40-60wt%), which can impair the cable's mechanical properties. Furthermore, organophosphorus flame retardants, while not producing toxic fumes, suffer from poor long-term stability and compatibility issues with polymers like polyethylene. Consequently, their practical application presents certain limitations.

[0004] Based on this, the present invention provides a flame retardant and fireproof wire and cable, which can solve the problems existing in the prior art. Summary of the Invention

[0005] In order to solve the problems mentioned in the background technology, the purpose of the present invention is to provide a flame retardant and fireproof wire and cable and a manufacturing process thereof.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A flame-retardant and fireproof wire and cable comprises, from the inside out, a conductor core layer, an inner lining layer, and an outer sheath layer; the outer sheath layer is formed by extruding and coating the outer sheath layer material on the outer side of the inner lining layer; the outer sheath layer material comprises the following raw materials in parts by weight: 55-68 parts of high-density polyethylene, 20-35 parts of linear low-density polyethylene, 5-15 parts of compatibilizer, 2-5.5 parts of organic-inorganic composite flame retardant, 5-10 parts of color powder, 1-2 parts of lubricant, 0.5-1.5 parts of antioxidant, and 0.5-1.5 parts of ultraviolet absorber.

[0007] As a further solution of the present invention, the preparation method of the outer sheath layer material is as follows: After weighing all the raw materials according to their weight, add them into a high-speed mixer and mechanically stir and mix them at a stirring rate of 1000-1500r / min for 20-40min to form a uniform material. Then transfer it to an extruder for melt extrusion, pelletize the obtained masterbatch, and dry it.

[0008] As a further embodiment of the present invention, the compatibilizer is maleic anhydride grafted polyethylene or maleic anhydride grafted polypropylene.

[0009] As a further embodiment of the present invention, the preparation method of the organic-inorganic composite flame retardant comprises the following steps: Step S1, adding rectorite to deionized water, ultrasonically oscillating the water evenly, then raising the temperature to 70-80°C, stirring for 1-2 hours, adjusting the pH to 9-10, and then adding 2,3-epoxypropyltrimethylammonium chloride. After the addition is complete, stirring at a constant temperature for 1-2 hours, stopping heating, cooling the water, discharging the water, washing the water, and vacuum drying the water to obtain an organic rectorite; Step S2, ultrasonically dispersing the organic rectorite in an N,N-dimethylformamide medium to form a uniform dispersion, then adding an excess of nitrogen / phosphorus integrated flame retardant monomer and catalyst to the dispersion, after the addition is completed, heating to 80-90°C, stirring at this temperature for 1-3 hours, and then continuing to add a chain extender. After the addition is completed, further heating to 100-120°C, continuously stirring and polymerizing for 12-24 hours, cooling and discharging the material, centrifuging the solid material, washing, and vacuum drying, to obtain an organic-inorganic composite flame retardant.

[0010] As a further embodiment of the present invention, in step S2, the catalyst is any one of N,N-dimethylbenzylamine, tetrabutylammonium hydrogen sulfate, tetramethylammonium bromide or tetrabutylammonium chloride.

[0011] As a further embodiment of the present invention, in step S2, the preparation method of the nitrogen / phosphorus integrated flame retardant monomer is as follows: 4-chloropyridine-2,6-dicarboxylic acid and FRC-2 in a molar ratio of 1:1 are added to toluene. After the addition is complete, mechanical stirring is performed to uniformly mix the mixture. Then, an alkaline catalyst is added. After the addition is complete, heating is turned on and the temperature is raised to 70-80°C. After stirring for 4-8 hours, the solvent is removed by rotary evaporation. The product is collected and purified to obtain a nitrogen / phosphorus integrated flame retardant monomer.

[0012] As a further embodiment of the present invention, the alkaline catalyst is an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution.

[0013] As a further embodiment of the present invention, the chain extender is 1,1,3,3-tetramethyl-1,3-bis[3-(oxiranylmethoxy)propyl]disiloxane.

[0014] In the above technical scheme, 2,3-epoxypropyltrimethylammonium chloride is first used to intercalate and modify rectorite to obtain an organic rectorite containing epoxy substituents. Then, a nitrogen / phosphorus integrated flame retardant monomer is used as a linker, and the substituted carboxyl group in its structure is first ring-opened esterified with the epoxy group of the organic rectorite. Then, the excess nitrogen / phosphorus integrated flame retardant monomer in the system and the epoxy group in the chain extender structure undergo continuous ring-opening reactions under the action of a catalyst, thereby forming a macromolecular modification connected by ester bonds in the rectorite. The macromolecular modification has a nitrogen / phosphorus flame retardant structure and a siloxane structure, and also contains a large number of hydroxyl functional groups produced by the ring-opening esterification reaction, thereby obtaining an organic-inorganic composite flame retardant.

[0015] The nitrogen / phosphorus integrated flame retardant monomer is prepared by using 4-chloropyridine-2,6-dicarboxylic acid and FRC-2 as raw materials, and reacting the halogen substituents and hydroxyl substituents in each other's structures under the action of an alkaline catalyst.

[0016] As a further embodiment of the present invention, the color powder is any one of titanium dioxide, carbon black or calcium carbonate; the lubricant is polyethylene wax or paraffin; the antioxidant is any one of antioxidant 1010, antioxidant 1076 or antioxidant 168; and the ultraviolet absorber is ultraviolet absorber UV-234 or ultraviolet absorber UV-326.

[0017] A manufacturing process for flame-retardant and fire-proof wires and cables, comprising the following steps: The first step is to twist the copper wires to form a conductor; The second step is to wrap the polyimide tape around the surface of the wire to form an inner lining layer, and then use extrusion equipment to extrude the outer sheath layer material and coat it on the surface of the inner lining layer to form an outer sheath layer.

[0018] Beneficial effects of the present invention: The present invention prepares an organic-inorganic composite flame retardant by forming a macromolecular modifier connected by ester bonds in rectorite. First, the hydroxyl substituent in the macromolecular modifier can interact with the anhydride group in the compatibilizer structure during the melt extrusion process, thereby achieving good compatibility between the rectorite and the polyethylene matrix. Moreover, since the macromolecular modifier and the polyethylene molecular chain form an intertwined network structure, the rectorite can also efficiently exert its own reinforcement effect in the form of a network core, so that the sheath layer exhibits higher mechanical strength. The macromolecular modifier itself contains carbon, nitrogen, phosphorus, and silicon elements. When combustion occurs, it can quickly catalyze the formation of an expanded carbon layer to isolate oxygen and heat. The silicon element can be deposited in the carbon layer in the form of oxide to maintain the strength of the carbon layer. In addition, the rectorite itself has a typical layered structure and can form a physical barrier. It cooperates with the expanded carbon layer to prevent the melt from dripping and slow down the spread of fire, thereby improving the fireproof and flame-retardant effect of the outer sheath layer.

[0019] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 This is the infrared test image of the nitrogen / phosphorus integrated flame retardant monomer. DETAILED DESCRIPTION

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making any creative efforts shall fall within the scope of protection of the present invention.

[0023] Example 1 Preparation of outer sheath material: Step 1: Add 55 parts of high-density polyethylene, 20 parts of linear low-density polyethylene, 5 parts of maleic anhydride-grafted polyethylene as a compatibilizer, 2 parts of an organic-inorganic composite flame retardant, 5 parts of a colorant titanium dioxide, 1 part of a lubricant polyethylene wax, 0.5 parts of an antioxidant 1010, and 0.5 parts of an ultraviolet absorber UV-234 into a high-speed blender, and mechanically stir and mix at a stirring rate of 1000 r / min for 40 minutes to form a uniform material; Step 2: Transfer the material to the extruder, control the temperature of each zone in sequence: zone 1 200±5℃, zone 2 210±5℃, zone 3 220±5℃, zone 4 220±5℃, zone 5 210±5℃, the screw speed is 150r / min, and melt extrusion is performed. The obtained masterbatch is pelletized and dried.

[0024] Example 2 Preparation of outer sheath material: Step 1: Add 60 parts of high-density polyethylene, 25 parts of linear low-density polyethylene, 10 parts of maleic anhydride-grafted polyethylene as a compatibilizer, 5 parts of an organic-inorganic composite flame retardant, 8 parts of a toner calcium carbonate, 1.5 parts of a lubricant polyethylene wax, 1 part of an antioxidant 1076, and 1 part of an ultraviolet absorber UV-326 into a high-speed blender, and mechanically stir and mix at a stirring rate of 1200 r / min for 30 minutes to form a uniform material; Step 2: Transfer the material to the extruder, control the temperature of each zone in sequence: zone 1 200±5℃, zone 2 210±5℃, zone 3 220±5℃, zone 4 220±5℃, zone 5 210±5℃, the screw speed is 150r / min, and melt extrusion is performed. The obtained masterbatch is pelletized and dried.

[0025] Example 3 Preparation of outer sheath material: Step 1: Add 68 parts of high-density polyethylene, 35 parts of linear low-density polyethylene, 15 parts of compatibilizer maleic anhydride grafted polyethylene, 5.5 parts of organic-inorganic composite flame retardant, 10 parts of color powder calcium carbonate, 2 parts of lubricant polyethylene wax, 1.5 parts of antioxidant 1076, and 1.5 parts of ultraviolet absorber UV-326 into a high-speed blender, and mechanically stir and mix at a stirring rate of 1500 r / min for 20 minutes to form a uniform material; Step 2: Transfer the material to the extruder, control the temperature of each zone in sequence: zone 1 200±5℃, zone 2 210±5℃, zone 3 220±5℃, zone 4 220±5℃, zone 5 210±5℃, the screw speed is 150r / min, and melt extrusion is performed. The obtained masterbatch is pelletized and dried.

[0026] The organic-inorganic composite flame retardant in the above embodiment is prepared by the following method: Step S1, adding 2.4 g of rectorite to deionized water, ultrasonically oscillating the mixture evenly, then raising the temperature to 75° C., stirring for 1 hour, adjusting the pH to 9, and then adding 1 g of 2,3-epoxypropyltrimethylammonium chloride. After the addition is complete, stirring at a constant temperature for 2 hours, stopping heating, cooling the mixture, washing it, and vacuum drying it to obtain an organic rectorite; Step S2, ultrasonically disperse 1.8g of organic rectorite in an N,N-dimethylformamide medium to form a uniform dispersion, and then add 6g of nitrogen / phosphorus integrated flame retardant monomer and 0.2g of tetrabutylammonium chloride to the dispersion. After the addition is completed, the temperature is raised to 85°C, and the mixture is stirred for 2h. Then, 5.8g of 1,1,3,3-tetramethyl-1,3-bis[3-(oxiranylmethoxy)propyl]disiloxane is added. After the addition is completed, the temperature is further raised to 110°C, and the polymerization is continuously stirred for 18h. The material is cooled and discharged, and the solid material is centrifuged. After washing and vacuum drying, an organic-inorganic composite flame retardant can be obtained.

[0027] The preparation method of the nitrogen / phosphorus integrated flame retardant monomer is as follows: 0.2 g of 4-chloropyridine-2,6-dicarboxylic acid and 0.2 g of FRC-2 in a molar ratio of 1:1 were added to toluene. After the addition was completed, mechanical stirring was carried out to uniformly stir the mixture. Then, 5 mL of a 20% by mass sodium hydroxide aqueous solution was added. After the addition was completed, heating was turned on and the temperature was raised to 75°C. After stirring for 6 hours, the solvent was removed by rotary evaporation, and the product was collected and purified to obtain a nitrogen / phosphorus integrated flame retardant monomer.

[0028] Figure 1 This is the infrared analysis test chart of the nitrogen / phosphorus integrated flame retardant monomer, where 3252cm -1 The characteristic absorption peak at 3000~3100cm is the NH characteristic absorption peak. -1 The characteristic absorption peak at 1709cm is attributed to the CH characteristic absorption peak in the pyridine ring. -1 The characteristic absorption peak of the carboxyl group C=O, 1675cm -1 The characteristic absorption peak at 1289 cm is the C=O characteristic absorption peak of the amide group. -1 The characteristic absorption peak that appears at 1000~1100cm is the P=O characteristic absorption peak. -1 The characteristic absorption peak appearing at is attributed to the characteristic absorption peak of ether bond CO produced by the substitution reaction.

[0029] Comparative Example 1 Preparation of outer sheath material: Step 1: Add 60 parts of high-density polyethylene, 25 parts of linear low-density polyethylene, 10 parts of maleic anhydride-grafted polyethylene as a compatibilizer, 5 parts of rectorite, 8 parts of color powder calcium carbonate, 1.5 parts of lubricant polyethylene wax, 1 part of antioxidant 1076, and 1 part of ultraviolet absorber UV-326 into a high-speed blender, and mechanically stir and mix at a stirring rate of 1200 r / min for 30 minutes to form a uniform material; Step 2: Transfer the material to the extruder, control the temperature of each zone in sequence: zone 1 200±5℃, zone 2 210±5℃, zone 3 220±5℃, zone 4 220±5℃, zone 5 210±5℃, the screw speed is 150r / min, and melt extrusion is performed. The obtained masterbatch is pelletized and dried.

[0030] Comparative Example 2 Preparation of outer sheath material: Step 1: Add 60 parts of high-density polyethylene, 25 parts of linear low-density polyethylene, 10 parts of maleic anhydride-grafted polyethylene as a compatibilizer, 8 parts of calcium carbonate as a color powder, 1.5 parts of polyethylene wax as a lubricant, 1 part of antioxidant 1076, and 1 part of ultraviolet absorber UV-326 into a high-speed blender, and mechanically stir and mix at a stirring rate of 1200 r / min for 30 minutes to form a uniform material; Step 2: Transfer the material to the extruder, control the temperature of each zone in sequence: zone 1 200±5℃, zone 2 210±5℃, zone 3 220±5℃, zone 4 220±5℃, zone 5 210±5℃, the screw speed is 150r / min, and melt extrusion is performed. The obtained masterbatch is pelletized and dried.

[0031] Performance Testing The materials in the examples and comparative examples were made into test samples that met the specifications and various performance tests were performed; According to the standard GB / T 1040.2-2022, tensile properties test is carried out; Impact performance test is carried out according to standard GB / T 1843-2008; According to the standard GB / T 2406-2009, the limiting oxygen index test is carried out; The test results are shown in the table below: Analysis of the test results shows that when unsurface-modified rectorite is directly used as a filler, the mechanical strength and flame retardant properties of the prepared sheath layer material are significantly reduced. On the one hand, due to the interface problem, agglomeration occurs, making it difficult to form an efficient reinforcement effect, resulting in a decline in mechanical properties. On the other hand, without the macromolecular modifier, the material cannot form an expanded carbon layer when it burns and can only rely on the barrier effect of the rectorite itself, so the flame retardant properties are also greatly reduced.

[0032] The outer sheath layer materials in Examples 1 to 3 of the present invention are used to manufacture a flame retardant and fireproof wire and cable. The specific manufacturing process includes the following steps: The first step is to twist the copper wires to form a conductor; The second step is to wrap the polyimide tape around the surface of the wire to form an inner lining layer, and then use extrusion equipment to extrude the outer sheath layer material and coat it on the surface of the inner lining layer to form an outer sheath layer.

[0033] Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enable any technician in the field to practice the present invention, including making and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the literal description of the claims, or if they include equivalent structural elements that are not substantially different from the literal description of the claims, then these other embodiments should also be included in the scope of the claims.

[0034] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A flame retardant and fireproof wire and cable, characterized in that: From the inside to the outside, it includes a conductor core layer, an inner lining layer and an outer sheath layer. The outer sheath layer is formed by extruding and coating the outer sheath layer material on the outer side of the inner lining layer. The outer sheath layer material includes the following raw materials in parts by weight: 55-68 parts of high-density polyethylene, 20-35 parts of linear low-density polyethylene, 5-15 parts of compatibilizer, 2-5.5 parts of organic-inorganic composite flame retardant, 5-10 parts of color powder, 1-2 parts of lubricant, 0.5-1.5 parts of antioxidant, and 0.5-1.5 parts of ultraviolet absorber.

2. The flame retardant and fireproof wire and cable according to claim 1, characterized in that: The preparation method of the outer sheath layer material is as follows: After weighing all the raw materials according to their weight, add them into a high-speed mixer and mechanically stir and mix them at a stirring rate of 1000-1500r / min for 20-40min to form a uniform material. Then transfer it to an extruder for melt extrusion, pelletize the obtained masterbatch, and dry it.

3. The flame retardant and fireproof wire and cable according to claim 1, characterized in that: The compatibilizer is maleic anhydride grafted polyethylene or maleic anhydride grafted polypropylene.

4. The flame retardant and fireproof wire and cable according to claim 1, characterized in that: The preparation method of the organic-inorganic composite flame retardant comprises the following steps: Step S1, using 2,3-epoxypropyltrimethylammonium chloride to perform intercalation modification on rectorite to obtain an organic rectorite; Step S2: In an N,N-dimethylformamide medium, using a catalyst, first using an excess of nitrogen / phosphorus integrated flame retardant monomer to further improve the organic rectorite, and then adding a chain extender to carry out continuous chain extension polymerization to obtain an organic-inorganic composite flame retardant.

5. The flame retardant and fireproof wire and cable according to claim 4, characterized in that: In step S2, the catalyst is any one of N,N-dimethylbenzylamine, tetrabutylammonium hydrogen sulfate, tetramethylammonium bromide or tetrabutylammonium chloride.

6. The flame retardant and fireproof wire and cable according to claim 4, characterized in that: In step S2, the nitrogen / phosphorus integrated flame retardant monomer is prepared by using 4-chloropyridine-2,6-dicarboxylic acid and FRC-2 in a molar ratio of 1:1 as raw materials and performing a substitution reaction under the action of an alkaline catalyst.

7. The flame retardant and fireproof wire and cable according to claim 6, characterized in that: The alkaline catalyst is a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution.

8. The flame retardant and fireproof wire and cable according to claim 4, characterized in that: The chain extender is 1,1,3,3-tetramethyl-1,3-bis[3-(oxiranylmethoxy)propyl]disiloxane.

9. The flame retardant and fireproof wire and cable according to claim 1, characterized in that: The color powder is any one of titanium dioxide, carbon black or calcium carbonate; the lubricant is polyethylene wax or paraffin; the antioxidant is any one of antioxidant 1010, antioxidant 1076 or antioxidant 168; the ultraviolet absorber is ultraviolet absorber UV-234 or ultraviolet absorber UV-326.

10. A process for manufacturing flame-retardant and fire-resistant wires and cables according to claim 1, characterized in that: The following steps are involved: The first step is to twist the copper wires to form a conductor; The second step is to wrap the polyimide tape around the surface of the wire to form an inner lining layer, and then use extrusion equipment to extrude the outer sheath layer material and coat it on the surface of the inner lining layer to form an outer sheath layer.

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