Novel inorganic mineral insulated flexible fireproof cable and preparation method thereof

Abstract

The invention discloses a novel inorganic mineral insulated flexible fireproof cable and a preparation method thereof. The novel inorganic mineral insulated flexible fireproof cable comprises a fire-resistant heat-insulating layer, a heat-absorbing fire-extinguishing layer, a buffer layer and a jacket layer which are sequentially arranged from inside to outside, a plurality of cable cores are arranged in the fire-resistant heat-insulating layer, the outer sides of the cable cores are coated with a mica tape insulating layer, and the space between the mica tape insulating layer and the fire-resistant heat-insulating layer is filled with inorganic flame-retardant filler; spiral embossing is arranged on the outer side wall of the heat absorption fire extinguishing layer, and a plurality of spiral hollowed-out grooves are formed in the outer side wall of the buffer layer along the peripheral side; and the heat-absorbing and fire-extinguishing layer adopts a steel wire woven and heat-absorbing and fire-extinguishing inorganic material extruded structure. According to the invention, a function of releasing water for multiple times along with temperature gradient change is formed on the heat absorption fire extinguishing layer, and the cooling effect on the surface of the cable is homogenized while cooling is delayed for multiple times through the spiral embossed structure and the spiral hollowed-out grooves in the buffer layer. The prepared fireproof cable is almost made of inorganic materials, almost does not generate toxic smoke, is good in environmental protection performance and has good practicability.

Description

Technical Field

[0001] The invention belongs to the technical field of inorganic mineral insulated flexible fireproof cables, and in particular relates to a novel inorganic mineral insulated flexible fireproof cable and a preparation method thereof. Background Art

[0002] Inorganic mineral insulated cables include rigid cables and flexible cables. Although rigid cables have superior fire resistance and do not burn, smoke or release gas under flame conditions, the weight of rigid cables is about twice that of ordinary cables, making them difficult to lay flat, and construction and maintenance are difficult. Flexible cables can produce multi-core and large-section cables, avoiding the installation and laying problems of rigid cables. At present, inorganic mineral insulated flexible fire-resistant cables are gradually replacing rigid inorganic mineral insulated cables. In recent years, in order to improve the safety level of electrical lines and reduce the occurrence of electrical fire accidents, the state has successively issued electrical design specifications, which clearly stipulate that inorganic mineral insulated flexible fire-resistant cables should be used in important electrical lines or places.

[0003] Inorganic mineral insulated flexible fireproof cable is different from ordinary flame-retardant cable. Its main function is to ensure that some important occasions or crowded places can continue to ensure normal power supply for a period of time after the fire occurs, so as to buy precious time for personnel evacuation or rescue. Secondly, it is necessary to have excellent fire resistance, low heat release energy during combustion, no smoke, and even cooling and delaying thermal damage. For example, CN108922672A discloses a medium and high voltage fireproof cable with a stepped water release and cooling structure, which includes a cable core containing a conductor, a cooling and fireproof layer with a water release and cooling characteristic outside the cable core, and a cooling and heat insulation armored fire barrier layer with a water release and cooling characteristic outside the cooling and fireproof layer. The critical temperature of the water release and cooling of the cooling and heat insulation armored fire barrier layer is higher than the critical temperature of the water release and cooling of the cooling and fireproof layer; the medium and high voltage fireproof cable with a stepped water release and cooling structure of the present invention, the cooling and heat insulation armored fire barrier layer and the cooling and fireproof layer form a stepped water release and cooling effect, which greatly delays the speed of fire and heat spreading inward. However, water release from the inner side of the cable core poses a potential risk of reducing the electrical performance of the cable, and may even cause the cable to short-circuit and break down. Summary of the invention

[0004] The object of the present invention is to provide a novel inorganic mineral insulated flexible fireproof cable and a preparation method thereof, aiming to solve the above-mentioned problems.

[0005] The present invention is mainly achieved through the following technical solutions: A novel inorganic mineral insulated flexible fireproof cable, comprising a fire-resistant insulation layer, a heat-absorbing fire-extinguishing layer, a buffer layer and an outer jacket layer arranged in sequence from the inside to the outside; a plurality of cable cores are arranged inside the fire-resistant insulation layer, the outer side of the cable core is coated with a mica tape insulation layer, and an inorganic flame-retardant filler is filled between the mica tape insulation layer and the fire-resistant insulation layer; the outer wall of the heat-absorbing fire-extinguishing layer is provided with a spiral embossing, and the outer wall of the buffer layer is provided with a plurality of spiral hollow grooves along the circumference; the heat-absorbing fire-extinguishing layer adopts a steel wire braiding + heat-absorbing fire-extinguishing inorganic material extrusion structure, and the heat-absorbing fire-extinguishing inorganic material comprises 15 to 20 parts of diatomaceous earth, 5 to 10 parts of refractory clay, 1 to 5 parts of gypsum, and 8 to 12 parts of magnesium hydroxide-calcium carbonate core-shell material.

[0006] Preferably, the outer wall of the connection end of the heat-absorbing and fire-extinguishing layer is provided with a spiral embossing, and the outer wall of the connection end of the buffer layer is provided with a plurality of spiral hollow grooves along the circumference. Alternatively, the entire outer wall of the heat-absorbing and fire-extinguishing layer is provided with a spiral embossing, and the entire outer wall of the buffer layer is provided with a plurality of spiral hollow grooves along the circumference. The present invention preferably releases water to cool down a large area in the area at the cable connection end.

[0007] In order to better realize the present invention, further, the fire-resistant heat-insulating layer includes an inner fire-resistant heat-insulating layer and an outer fire-resistant heat-insulating layer, and a ceramic fireproof layer or an armor structure layer is arranged between the inner fire-resistant heat-insulating layer and the outer fire-resistant heat-insulating layer.

[0008] In order to better realize the present invention, further, the fire-resistant heat-insulating layer adopts an inorganic tape wrapping structure with fire-proof properties.

[0009] In order to better realize the present invention, further, the components of the inorganic flame retardant filler include the following calculated by weight: 2 to 5 parts of kaolin, the average particle size of kaolin is 4 μm, 5 to 10 parts of crushed mica, 10 to 15 parts of raw gypsum, 10 to 20 parts of magnesium oxide, 20 to 30 parts of quartz powder, the average particle size of quartz powder is 12 μm, 10 to 15 parts of aluminum oxide, 5 to 10 parts of beryllium oxide, and 5 to 10 parts of zirconium oxide.

[0010] In order to better realize the present invention, further, the composition of the inorganic flame retardant filler includes the following components calculated by weight: 2 to 5 parts of kaolin, 20 to 30 parts of refractory clay, 1 to 5 parts of silica sol, 0.2 to 1.5 parts of gypsum, 10 to 20 parts of magnesium oxide, 10 to 20 parts of quartz powder, 5 to 10 parts of beryllium oxide, and 5 to 10 parts of zirconium oxide.

[0011] In order to better realize the present invention, further, the buffer layer is prepared by using an inorganic compound material of expandable graphite.

[0012] The present invention is mainly achieved through the following technical solutions: A method for preparing a novel inorganic mineral insulated flexible fireproof cable comprises the following steps: Step S100: preparing a cable core and coating the outer side of the cable core with a mica tape insulation layer; Step S200: Plying a plurality of coated cable cores prepared in step S100 into a master cable, and coating the master cable with an inorganic flame retardant filler by an extrusion process; and then wrapping a fire-resistant insulation layer by a wrapping process; Step S300: using weaving + extrusion to form a steel wire braid outside the fire-resistant insulation layer, and at the same time extruding and filling the heat-absorbing fire-extinguishing inorganic material to form a heat-absorbing fire-extinguishing layer; Step S400: forming a buffer layer outside the heat absorbing and fire extinguishing layer; Step S500: Finally, a jacket layer is formed outside the buffer layer.

[0013] In order to better implement the present invention, further, in the step S200, firstly wrapping is performed to form an inner fire-resistant heat-insulating layer, then armor is interlocked on the outer side of the inner fire-resistant heat-insulating layer to form an armor structure layer, and finally wrapping is performed to form an outer fire-resistant heat-insulating layer.

[0014] The beneficial effects of the present invention are as follows: (1) The present invention integrates the fireproof functions of flame retardancy, fire resistance, heat insulation, armoring, cooling, and heat buffering, ensuring the fireproof performance and electrical performance of the inner cable core, and realizing the functions of fire isolation, strengthening mechanical strength, and shielding electromagnetic signals through the armor structure. The present invention forms a function of multiple water releases that changes with the temperature gradient through the heat-absorbing fire extinguishing layer, and realizes multiple delays in cooling through the spiral embossed structure and the spiral hollow grooves on the buffer layer, while also homogenizing the cooling effect on the cable surface. The fireproof cable prepared by the present invention is almost entirely made of inorganic materials, produces almost no toxic smoke, and has good environmental performance.

[0015] (2) In the heat-absorbing fire-extinguishing layer, porous diatomaceous earth is used as a loading matrix, and magnesium hydroxide-calcium carbonate core-shell material and gypsum are loaded, and then refractory clay is assisted to adjust into a soft structure. The mass ratio of magnesium hydroxide and calcium carbonate in the magnesium hydroxide-calcium carbonate core-shell material is 1-1.2:0.8-1, and the preparation method is the prior art, such as the preparation method disclosed in the existing patent 201410052412X. The magnesium hydroxide-calcium carbonate core-shell material has both the excellent flame retardant and smoke suppression properties of magnesium hydroxide and the excellent filling process performance of calcium carbonate, wherein the magnesium hydroxide-calcium carbonate core-shell material increases the compatibility of the overall filler. Gypsum can enhance mechanical properties and assist flame retardant and smoke suppression properties.

[0016] (3) The chemical composition of gypsum is calcium sulfate dihydrate. When heated, there are three stages of expelling crystal water: 105~180℃, first one water molecule is expelled, and then half of the water molecule is immediately expelled, turning into calcined gypsum Ca[SO4]·0.5H2O, also known as gypsum or semi-hydrated gypsum. At 200~220℃, the remaining half of the water molecule is expelled and it turns into type III anhydrite Ca[SO4]·εH2O (0.06<ε<0.11). At about 350℃, it turns into type II gypsum CaSO4. At 300℃-350℃, magnesium hydroxide will dehydrate and decompose, releasing water, further intensifying the cooling effect and extending the service life of the cable, which has good practicality.

[0017] (3) In the inorganic flame retardant filler, the present invention uses refractory clay and silica sol to further modify the compactness of the flame retardant filler, further improving the flame retardant effect of the fireproof cable and having good practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the structure of the novel inorganic mineral insulated flexible fireproof cable in Example 1; Figure 2 This is a schematic diagram of the structure of the novel inorganic mineral insulated flexible fire-resistant cable in Example 2; Figure 3 It is a structural schematic diagram of the external thread corrugated structure of the heat absorbing and fire extinguishing layer; Figure 4 Schematic diagram of the structure of the spiral hollow groove of the buffer layer.

[0019] Among them: 1-fire-resistant insulation layer, 101-inner fire-resistant insulation layer, 102-outer fire-resistant insulation layer, 2-heat-absorbing fire-extinguishing layer, 3-buffer layer, 4-jacket layer, 5-spiral hollow groove, 6-armored structure layer, 7-cable core, 8-mica tape insulation layer. DETAILED DESCRIPTION

[0020] Embodiment 1: A new type of inorganic mineral insulated flexible fireproof cable, such as Figure 1 As shown, it includes a fire-resistant insulation layer 1, a heat-absorbing fire-extinguishing layer 2, a buffer layer 3 and a jacket layer 4 arranged in sequence from the inside to the outside; a plurality of cable cores 7 are arranged inside the fire-resistant insulation layer 1, and the outer side of the cable core 7 is coated with a mica tape insulation layer 8, and an inorganic flame retardant filler is filled between the mica tape insulation layer 8 and the fire-resistant insulation layer 1. The components of the inorganic flame retardant filler include the following by weight: 2 to 5 parts of kaolin, 20 to 30 parts of refractory clay, 1 to 5 parts of silica sol, 0.2 to 1.5 parts of gypsum, 10 to 20 parts of magnesium oxide, 10 to 20 parts of quartz powder, 5 to 10 parts of beryllium oxide, and 5 to 10 parts of zirconium oxide. The fire-resistant insulation layer 1 includes a mica tape, a fireproof cloth and a heat-insulating fire-resistant layer arranged in sequence from the inside to the outside.

[0021] like Figure 3 and Figure 4 As shown, the outer wall of the heat-absorbing and fire-extinguishing layer 2 is provided with a spiral embossing, and the outer wall of the buffer layer 3 is provided with a plurality of spiral hollow grooves 5 along the circumference.

[0022] The buffer layer 3 is prepared by an inorganic compound material of expandable graphite; the endothermic fire extinguishing layer 2 adopts a steel wire weaving + endothermic fire extinguishing inorganic material extrusion structure, and the endothermic fire extinguishing inorganic material includes 15 to 20 parts of diatomaceous earth, 5 to 10 parts of refractory clay, 1 to 5 parts of gypsum, and 8 to 12 parts of magnesium hydroxide-calcium carbonate core-shell material.

[0023] The inorganic compound material of expandable graphite begins to expand at about 200°C. When heated to a certain degree, the expansion volume can increase to about 200 times, forming an insulating layer, which can play an excellent role in fire resistance, heat insulation and flame impact prevention, and can effectively block the spread of fire and heat to the center of the cable. The spiral hollow groove 5 can delay the expansion effect and has the process of releasing water and cooling. The heat-absorbing fire-extinguishing layer 2 uses porous diatomaceous earth as the loading matrix, and loads magnesium hydroxide-calcium carbonate core-shell material and gypsum, and then assists refractory clay to adjust into a soft structure. At 105~180°C, calcium sulfate dihydrate first discharges 1 water molecule, and then immediately discharges half of the water molecule, turning into burnt gypsum Ca[SO4]·0.5H2O, also known as gypsum or semi-hydrated gypsum. At 200~220°C, the remaining half of the water molecule is discharged and turned into type III anhydrite Ca[SO4]·εH2O (0.06<ε<0.11). At about 350℃, it turns into type II gypsum CaSO4. At 300℃-350℃, magnesium hydroxide will dehydrate and decompose, releasing water, further intensifying the cooling effect, extending the service life of the cable, and having good practicality.

[0024] Embodiment 2: A new type of inorganic mineral insulated flexible fireproof cable, such as Figure 2 As shown, it includes an inner fire-resistant insulation layer 101, an armored structure layer 6, an outer fire-resistant insulation layer 102, a heat-absorbing fire-extinguishing layer 2, a buffer layer 3 and an outer jacket layer 4 arranged in sequence from the inside to the outside; a plurality of cable cores 7 are arranged inside the fire-resistant insulation layer 1, and the outer side of the cable core 7 is coated with a mica tape insulation layer 8, and an inorganic flame retardant filler is filled between the mica tape insulation layer 8 and the fire-resistant insulation layer 1. The components of the inorganic flame retardant filler include the following in parts by weight: 2 to 5 parts of kaolin, 20 to 30 parts of refractory clay, 1 to 5 parts of silica sol, 0.2 to 1.5 parts of gypsum, 10 to 20 parts of magnesium oxide, 10 to 20 parts of quartz powder, 5 to 10 parts of beryllium oxide, and 5 to 10 parts of zirconium oxide.

[0025] The inner refractory heat-insulating layer 101 and the outer refractory heat-insulating layer 102 are both mica tapes.

[0026] like Figure 3 and Figure 4 As shown, the outer wall of the heat-absorbing and fire-extinguishing layer 2 is provided with a spiral embossing, and the outer wall of the buffer layer 3 is provided with a plurality of spiral hollow grooves 5 along the circumference.

[0027] The buffer layer 3 is prepared by an inorganic compound material of expandable graphite; the endothermic fire extinguishing layer 2 adopts a steel wire weaving + endothermic fire extinguishing inorganic material extrusion structure, and the endothermic fire extinguishing inorganic material includes 15 to 20 parts of diatomaceous earth, 5 to 10 parts of refractory clay, 1 to 5 parts of gypsum, and 8 to 12 parts of magnesium hydroxide-calcium carbonate core-shell material.

[0028] The preparation method of the novel inorganic mineral insulated flexible fireproof cable comprises the following steps: Step S100: preparing a cable core 7, and coating the outer side of the cable core 7 with a mica tape insulation layer 8; Step S200: Plying a plurality of coated cable cores 7 prepared in step S100 into a master cable, and coating the outer surface of the master cable with an inorganic flame retardant filler by an extrusion process; then, wrapping the outer surface of the master cable by a wrapping process, first wrapping to form an inner fire-resistant heat-insulating layer 101, then interlocking armoring on the outer side of the inner fire-resistant heat-insulating layer 101 to form an armor structure layer 6, and finally wrapping to form an outer fire-resistant heat-insulating layer 102; Step S300: using weaving + extrusion to form a steel wire braid outside the fire-resistant insulation layer 1, and at the same time extruding and filling the heat-absorbing fire-extinguishing inorganic material to form the heat-absorbing fire-extinguishing layer 2; Step S400: forming a buffer layer 3 outside the heat absorbing and fire extinguishing layer 2; Step S500: finally forming the outer cover layer 4 outside the buffer layer 3 .

[0029] The present invention integrates the fireproof functions of flame retardancy, fire resistance, heat insulation, armoring, cooling, and heat buffering, ensures the fireproof performance and electrical performance of the inner cable core 7, and realizes the functions of fire isolation, strengthening mechanical strength, and shielding electromagnetic signals through the armored structure. The present invention forms multiple releases of water that change with the temperature gradient through the heat-absorbing fire extinguishing layer 2, and through the spiral embossed structure and the spiral hollow groove 5 on the buffer layer 3, it realizes multiple delays in cooling while also homogenizing the cooling effect on the cable surface. The fireproof cable prepared by the present invention is almost all made of inorganic materials, almost no toxic smoke is generated, and has good environmental protection performance. In the inorganic flame retardant filler, refractory clay and silica sol are used to modify the compactness of the flame retardant filler again, further improving the flame retardant effect of the fireproof cable.

[0030] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A new type of inorganic mineral insulated flexible fireproof cable, characterized in that: The invention comprises a fire-resistant insulation layer (1), a heat-absorbing fire-extinguishing layer (2), a buffer layer (3) and an outer jacket layer (4) which are arranged in sequence from the inside to the outside; a plurality of cable cores (7) are arranged inside the fire-resistant insulation layer (1); the outer side of the cable core (7) is coated with a mica tape insulation layer (8); an inorganic flame-retardant filler is filled between the mica tape insulation layer (8) and the fire-resistant insulation layer (1); the outer side wall of the heat-absorbing fire-extinguishing layer (2) is provided with a spiral embossing; the outer side wall of the buffer layer (3) is provided with a plurality of spiral hollow grooves (5) along the circumference; the heat-absorbing fire-extinguishing layer (2) adopts a steel wire braiding + heat-absorbing fire-extinguishing inorganic material extrusion structure; the heat-absorbing fire-extinguishing inorganic material comprises 15 to 20 parts of diatomaceous earth, 5 to 10 parts of refractory clay, 1 to 5 parts of gypsum, and 8 to 12 parts of magnesium hydroxide-calcium carbonate core-shell material.

2. A novel inorganic mineral insulated flexible fireproof cable according to claim 1, characterized in that: The fire-resistant heat-insulating layer (1) comprises an inner fire-resistant heat-insulating layer (101) and an outer fire-resistant heat-insulating layer (102), and a ceramic fireproof layer or an armored structural layer (6) is provided between the inner fire-resistant heat-insulating layer (101) and the outer fire-resistant heat-insulating layer (102).

3. A novel inorganic mineral insulated flexible fireproof cable according to claim 2, characterized in that: The fire-resistant heat-insulating layer (1) adopts an inorganic tape wrapping structure with fire-proof properties.

4. A novel inorganic mineral insulated flexible fireproof cable according to claim 1, characterized in that: The inorganic flame retardant filler comprises the following components calculated by weight: 2 to 5 parts of kaolin, the average particle size of the kaolin is 4 μm, 5 to 10 parts of crushed mica, 10 to 15 parts of raw gypsum, 10 to 20 parts of magnesium oxide, 20 to 30 parts of quartz powder, the average particle size of the quartz powder is 12 μm, 10 to 15 parts of aluminum oxide, 5 to 10 parts of beryllium oxide, and 5 to 10 parts of zirconium oxide.

5. A novel inorganic mineral insulated flexible fireproof cable according to claim 1, characterized in that: The inorganic flame retardant filler comprises the following components calculated by weight: 2 to 5 parts of kaolin, 20 to 30 parts of refractory clay, 1 to 5 parts of silica sol, 0.2 to 1.5 parts of gypsum, 10 to 20 parts of magnesium oxide, 10 to 20 parts of quartz powder, 5 to 10 parts of beryllium oxide, and 5 to 10 parts of zirconium oxide.

6. A novel inorganic mineral insulated flexible fireproof cable according to any one of claims 1 to 5, characterized in that: The buffer layer (3) is prepared using an inorganic compound material of expandable graphite.

7. A method for preparing a novel inorganic mineral insulated flexible fireproof cable, characterized in that: The following steps are involved: Step S100: preparing a cable core (7), and coating the outer side of the cable core (7) with a mica tape insulation layer (8); Step S200: Plying a plurality of coated cable cores (7) prepared in step S100 into a master cable, and coating the master cable with an inorganic flame retardant filler by extrusion process; Then, a refractory insulation layer (1) is wrapped around the outer surface of the refractory insulation layer by a wrapping process; Step S300: using weaving + extrusion to form a steel wire braid outside the fire-resistant insulation layer (1), and at the same time extruding and filling a heat-absorbing fire-extinguishing inorganic material to form a heat-absorbing fire-extinguishing layer (2); Step S400: forming a buffer layer (3) outside the heat-absorbing and fire-extinguishing layer (2); Step S500: Finally, a jacket layer (4) is formed outside the buffer layer (3).

8. The method for preparing a novel inorganic mineral insulated flexible fireproof cable according to claim 7, characterized in that: In the step S200, firstly, wrapping is performed to form an inner fire-resistant heat-insulating layer (101), then armor is interlocked on the outer side of the inner fire-resistant heat-insulating layer (101) to form an armor structure layer (6), and finally wrapping is performed to form an outer fire-resistant heat-insulating layer (102).

Images