Fireproof cable production process

Abstract

The invention relates to the technical field of cables, in particular to a fireproof cable production process, and a cable produced by the fireproof cable production process sequentially comprises a conductor, a ceramic polyolefin fireproof layer, a mica heat insulation layer, an inner sheath, an armor layer and an outer sheath from inside to outside. The conductor is formed by pressing and twisting three strands of conductive wire cores, and further, each conductive wire core sequentially comprises a copper core body, an inner shielding layer, an insulating layer, an outer shielding layer and an isolating layer from inside to outside. The cable produced by the invention is good in fireproof and high-temperature-resistant performance, safe and reliable, strong in anti-electromagnetic interference performance, convenient to construct and long in service life.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and more particularly to a production process of fireproof cables. Background Art

[0002] Cables are made of one or more mutually insulated conductors and an outer insulating protective layer, and are used to transmit electricity or information from one place to another. Cables are divided into many types according to their functions and environments. Existing cables are divided into fireproof cables, wear-resistant cables, signal cables, shielded cables, and marine cables. Existing fireproof cables usually only have one fireproof layer inside the cable. In the event of a serious fire, it is easy for the flame to penetrate the fireproof layer, causing the insulation layer on the conductor inside the cable to burn and fall off, resulting in leakage, which poses a safety hazard to fire rescue work.

[0003] Existing Chinese patents such as announcement number CN108962495B disclose a fireproof flexible cable production process, including unwinding, straightening, injection molding, coating, cabling and winding. The straightening setting is first used to straighten the cable during processing, so that the cable will not have uneven wall thickness during injection molding. The injection-molded insulation layer is coated to form a fireproof layer, and then the sheath is coated on the outermost surface to form the entire cable.

[0004] The above-mentioned existing technical solutions have the following defects: the cables produced by the cable production process are only provided with one fireproof layer, which is not conducive to preventing flame penetration. When the fire disaster is serious, it is easy to cause damage to the cable insulation layer, causing certain safety hazards to the fire rescue work. Summary of the invention

[0005] The purpose of the present invention is to provide a fireproof cable production process, wherein the produced cable has the effect of preventing flame penetration and provides stronger protection for the cable insulation layer, thereby facilitating the elimination of potential safety hazards during fire rescue work.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions:

[0007] A fireproof cable production process comprises the following steps:

[0008] (1) Use an extruder to extrude an inner shielding layer on the outside of the copper core;

[0009] (2) Using an extruder to extrude an insulating layer on the outside of the inner shielding layer;

[0010] (3) Using an extruder to extrude an outer shielding layer outside the insulating layer;

[0011] (4) wrapping an isolation layer around the outer side of the outer shielding layer to form a conductive core;

[0012] (5) Compressing and twisting three conductive wire cores together to form a conductor;

[0013] (6) using an extruder to extrude a ceramicized polyolefin refractory layer on the outside of the conductor;

[0014] (7) wrapping a mica insulation layer around the outside of the ceramicized polyolefin refractory layer;

[0015] (8) using an extruder to extrude an inner sheath on the outside of the mica insulation layer;

[0016] (9) Wrapping an armor layer around the outer side of the inner sheath;

[0017] (10) An extruder is used to extrude an outer sheath on the outside of the armor layer to obtain a fireproof cable.

[0018] Preferably, taking the total mass percentage of the insulating layer as 100%, the insulating layer comprises 70-80% polyphenylene sulfide, 3-5% toughening agent, 5-10% lubricant, and 10-20% modified boron nitride / magnesium oxide composite filler.

[0019] Preferably, the preparation method of the modified boron nitride / magnesium oxide composite filler comprises the following steps: dispersing boron nitride and dopamine hydrochloride in a solvent consisting of tris(hydroxymethyl)aminomethane buffer and ethanol, and then stirring at room temperature for 10-12 hours to obtain a polydopamine-modified boron nitride dispersion; adding γ-aminopropyltriethoxysilane to the polydopamine-modified boron nitride dispersion, and then stirring at 60-80°C for 4-6 hours, and then filtering and drying to obtain modified boron nitride; dispersing magnesium oxide and γ-glycidyloxypropyltrimethoxysilane in a solvent consisting of methanol and acetone, and then stirring at a stirring rate of 60-80°C for 6-8 hours, and then filtering and drying to obtain modified magnesium oxide; dispersing modified boron nitride and modified magnesium oxide in a solvent, and then stirring at 60-80°C for 6-8 hours, and then filtering and drying to obtain a modified boron nitride / magnesium oxide composite filler.

[0020] Preferably, the method for preparing the insulating layer comprises the following steps: mixing polyphenylene sulfide, a toughening agent and a lubricant, and kneading them at 280-320°C for 15-20 minutes to obtain a reaction mixture; kneading the modified boron nitride / magnesium oxide composite filler with the reaction mixture at 300-320°C for 5-10 minutes, granulating after cooling, to obtain insulating particles; and extruding the insulating particles onto the inner shielding layer to form an insulating layer.

[0021] Preferably, the isolation layer is a polyester film layer, which plays an isolating and tightening role, so that the outer shielding layer is separated from the ceramic polyolefin fire-resistant layer, and the wear of the ceramic polyolefin fire-resistant layer on the outer shielding layer is reduced.

[0022] Preferably, the outer armor layer is a galvanized steel belt layer, which not only increases the mechanical strength of the cable, but also serves to prevent the flame from spreading into the interior of the cable.

[0023] Preferably, the outer shielding plastic particles, insulating particles and inner shielding plastic particles are heated to a viscous flow state by an extruder, and then respectively extruded onto the copper core through the outer die, middle die and inner die of the extruder, thereby improving production efficiency.

[0024] Preferably, both the outer shielding plastic particles and the inner shielding plastic particles are TPE, thereby improving the flexibility of the cable.

[0025] Preferably, the materials of the inner sheath and the outer sheath are both polyvinyl chloride, which can provide a certain degree of protection for the structure of the mica thermal insulation layer, and the mica thermal insulation layer itself has the functions of thermal insulation, cooling and isolation.

[0026] The above-mentioned embodiments of the present invention have the following beneficial effects: the fireproof cable prepared by the present invention has a multi-layer flame-blocking structure, excellent fireproof performance, stronger protection for the cable insulation layer, and prevents the cable insulation layer from being damaged in the event of a fire, thereby facilitating the elimination of safety hazards during fire rescue work. In addition, the present invention modifies magnesium oxide and boron nitride to prepare a special boron nitride / magnesium oxide composite filler, and then mixes the prepared filler with polyphenylene sulfide, a toughening agent, and a lubricant into particles, and forms an insulating layer wrapped on the inner shielding layer through an extrusion process. On the premise of ensuring the mechanical and electrical properties of the insulating layer, on the one hand, the amount of magnesium oxide added as insulating particles is reduced, thereby reducing the cost of insulating particles; on the other hand, magnesium oxide and boron nitride are filled into polyphenylene sulfide resin as thermally conductive insulating seasonings, and wrapped on the inner shielding layer through an extrusion process, eliminating the filling and compaction processes, thereby reducing the cost from the production process of the fireproof cable production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic cross-sectional view of a cable produced by the fireproof cable production process of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings. Several embodiments of the present invention are shown in the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein.

[0029] The present invention is described in detail below in conjunction with the accompanying drawings and embodiments.

[0030] Example 1

[0031] A fireproof cable production process comprises the following steps:

[0032] (1) An inner shielding layer 2 is extruded on the outer side of the copper core 1 by using an extruder;

[0033] (2) using an extruder to extrude an insulating layer 3 on the outer side of the inner shielding layer 2;

[0034] (3) using an extruder to extrude an outer shielding layer 4 on the outside of the insulating layer 3;

[0035] (4) wrapping an isolation layer 5 around the outer side of the outer shielding layer 4 to form a conductive core;

[0036] (5) Compressing and twisting three conductive wire cores together to form a conductor;

[0037] (6) using an extruder to extrude a ceramic polyolefin refractory layer 6 on the outside of the conductor;

[0038] (7) wrapping a mica heat insulation layer 7 around the outside of the ceramicized polyolefin refractory layer 6;

[0039] (8) using an extruder to extrude an inner sheath 8 on the outside of the mica insulation layer 7;

[0040] (9) wrapping an armor layer 9 around the outer side of the inner sheath 8;

[0041] (10) An extruder is used to extrude an outer sheath 10 on the outside of the armor layer 9 to obtain a fireproof cable.

[0042] The specific process steps are as follows:

[0043] Steps (1) to (3) adopt a three-layer extrusion process, that is, the outer shielding plastic particles (TPE), the insulating particles and the inner shielding plastic particles (TPE) are heated to a viscous flow state by an extruder, and then extruded onto the copper core 1 through the outer mold, the middle mold and the inner mold of the extruder respectively.

[0044] In step (4), the isolation layer 5 is formed by wrapping a polyester film tape.

[0045] In step (6), the ceramicized polyolefin particles are heated to a viscous fluid state by an extruder, and then extruded onto a conductor by the extruder.

[0046] In step (8), the polyvinyl chloride particles are heated to a viscous fluid state by an extruder, and then extruded onto the mica insulation layer 7 by the extruder.

[0047] In step (9), the armor layer 9 is formed by wrapping a galvanized steel strip.

[0048] In step (10), the polyvinyl chloride particles are heated to a viscous fluid state by an extruder, and then extruded onto the armor layer 9 by the extruder.

[0049] The insulating layer 2 in this embodiment is obtained by extrusion molding of insulating particles, and the insulating particles are prepared by the following preparation method:

[0050] (1) 10 parts of hexagonal boron nitride and 1 part of dopamine hydrochloride are dispersed in a solvent consisting of 100 parts of tris(hydroxymethyl)aminomethane buffer and 30 parts of ethanol, and then stirred at 600 rpm for 10 hours at room temperature to obtain a polydopamine-modified boron nitride dispersion; 1 part of γ-aminopropyltriethoxysilane is added to the polydopamine-modified boron nitride dispersion, and then stirred at 600 rpm for 5 hours at 80°C, and then negative pressure filtered, and vacuum dried at 80°C for 12 hours to obtain modified boron nitride; 15 parts of spherical magnesium oxide are added to the polydopamine-modified boron nitride dispersion; and 1 part of γ-glycidyloxypropyltrimethoxysilane are dispersed in a solvent consisting of 145 parts of methanol and 5 parts of acetone, and then stirred at 600 rpm at 80°C for 8 hours, then filtered under negative pressure, and dried in vacuum at 80°C for 12 hours to obtain modified magnesium oxide; 15 parts of modified boron nitride and 15 parts of modified magnesium oxide are dispersed in 200 parts of ethanol solvent, and then stirred at 1000 rpm at 80°C for 8 hours, then filtered under negative pressure, and dried in vacuum at 80°C for 12 hours to obtain modified boron nitride / magnesium oxide composite filler.

[0051] (2) Based on the total mass of the insulating layer being 100%, 75% of polyphenylene sulfide, 5% of a toughening agent (ethylene-methyl acrylate-glycidyl methacrylate copolymer), and 10% of a lubricant (vinyl bisstearamide) were mixed and kneaded at 300°C for 20 minutes to obtain a reaction mixture; 10% of the above-mentioned modified boron nitride / magnesium oxide composite filler was mixed with the reaction mixture at 300°C for 10 minutes, and granulated after cooling to obtain insulating particles.

[0052] Example 2

[0053] A fireproof cable production process, which differs from Example 1 in that the material composition of the insulation layer is different. Taking the total mass of the insulation layer in this embodiment as 100%, it includes 70% polyphenylene sulfide, 3% toughening agent, 10% lubricant and 17% modified boron nitride / magnesium oxide composite filler.

[0054] Example 3

[0055] A fireproof cable production process, which differs from Example 1 in that the material composition of the insulation layer is different. Taking the total mass of the insulation layer in this embodiment as 100%, it includes 80% polyphenylene sulfide, 5% toughening agent, 5% lubricant and 10% modified boron nitride / magnesium oxide composite filler.

[0056] Comparative Example 1

[0057] The commercially available spherical magnesium oxide is used as the insulating layer material, and its size is 10-20 μm.

[0058] The mechanical and electrical properties of the insulating layers in the above-mentioned Examples 1-3 and Comparative Example 1 were tested respectively. For mechanical properties, tensile strength and tensile modulus were tested according to the ASTM D638 method, and bending tests were performed according to the ASTM D790 method. For electrical properties, the breakdown strength test was performed according to the GB1408.1-2016 insulating particle electrical strength test method. The following data were obtained:

[0059] Table 1 Performance test data of each insulation layer material

[0060]

[0061]

[0062] As can be seen from Table 1, the tensile strength, tensile modulus, flexural modulus and breakdown strength of the insulating layer prepared in Examples 1-3 of the present invention are all higher than those in Comparative Example 1, and have better mechanical properties and better insulation properties, and can be used as excellent insulating layer materials in the production process of fire-resistant cables.

[0063] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A fireproof cable production process, characterized in that: The following steps are involved: (1) Use an extruder to extrude an inner shielding layer on the outside of the copper core; (2) Using an extruder to extrude an insulating layer on the outside of the inner shielding layer; (3) Using an extruder to extrude an outer shielding layer outside the insulating layer; (4) wrapping an isolation layer around the outer side of the outer shielding layer to form a conductive core; (5) Compressing and twisting three conductive wire cores together to form a conductor; (6) using an extruder to extrude a ceramicized polyolefin refractory layer on the outside of the conductor; (7) wrapping a mica insulation layer around the outside of the ceramicized polyolefin refractory layer; (8) using an extruder to extrude an inner sheath on the outside of the mica insulation layer; (9) Wrapping an armor layer around the outer side of the inner sheath; (10) An extruder is used to extrude an outer sheath on the outside of the armor layer to obtain a fireproof cable.

2. The fireproof cable production process according to claim 1, characterized in that: Taking the total mass percentage of the insulating layer as 100%, the insulating layer comprises 70-80% of polyphenylene sulfide, 3-5% of a toughening agent, 5-10% of a lubricant, and 10-20% of a modified boron nitride / magnesium oxide composite filler.

3. The fireproof cable production process according to claim 2, characterized in that: The preparation method of the modified boron nitride / magnesium oxide composite filler comprises the following steps: dispersing boron nitride and dopamine hydrochloride in a solvent consisting of trishydroxymethylaminomethane buffer and ethanol, and then stirring at room temperature for 10-12 hours to obtain a polydopamine-modified boron nitride dispersion; adding γ-aminopropyltriethoxysilane to the polydopamine-modified boron nitride dispersion, and then stirring at 60-80°C for 4-6 hours, and then filtering and drying to obtain modified boron nitride; dispersing magnesium oxide and γ-glycidyloxypropyltrimethoxysilane in a solvent consisting of methanol and acetone, and then stirring at a stirring rate of 60-80°C for 6-8 hours, and then filtering and drying to obtain modified magnesium oxide; dispersing modified boron nitride and modified magnesium oxide in a solvent, and then stirring at 60-80°C for 6-8 hours, and then filtering and drying to obtain a modified boron nitride / magnesium oxide composite filler.

4. The fireproof cable production process according to claim 3, characterized in that: The preparation method of the insulating layer comprises the following steps: mixing polyphenylene sulfide, a toughening agent and a lubricant, and kneading them at 280-320°C for 15-20 minutes to obtain a reaction mixture; kneading the modified boron nitride / magnesium oxide composite filler and the reaction mixture at 300-320°C for 5-10 minutes, granulating after cooling, and obtaining insulating particles; and extruding the insulating particles on the inner shielding layer to form an insulating layer.

5. The fireproof cable production process according to claim 1, characterized in that: The isolation layer is a polyester film layer.

6. The fireproof cable production process according to claim 1, characterized in that: The outer armor layer is a galvanized steel belt layer.

7. The fireproof cable production process according to claim 1, characterized in that: The outer shielding plastic particles, insulating particles and inner shielding plastic particles are heated to a viscous flow state by an extruder, and then are respectively extruded onto the copper core through an outer die, a middle die and an inner die of the extruder.

8. The fireproof cable production process according to claim 7, characterized in that: The outer shielding plastic particles and the inner shielding plastic particles are both TPE.

9. The fireproof cable production process according to claim 1, characterized in that: The materials of the inner sheath and the outer sheath are both polyvinyl chloride.

10. A fireproof cable, characterized in that: The invention is produced by the production process described in any one of claims 1 to 9.

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