Environment-friendly high-temperature-resistant fireproof special cable and preparation method thereof

Abstract

The invention relates to the technical field of cables, and provides an environment-friendly high-temperature-resistant fireproof special cable and a preparation method thereof.The environment-friendly high-temperature-resistant fireproof special cable comprises a cable core, a shielding layer and an outer sheath, the cable core comprises a plurality of mutually-twisted wires, a first insulating layer and a second insulating layer, and the first insulating layer and the second insulating layer wrap the outer sides of the wires from inside to outside; a through hole is formed in the second insulating layer in the axial direction, a fire-retardant strip is arranged in the through hole, the fire-retardant strip is filled with fire-retardant filler, and the fire-retardant filler can move in the fire-retardant strip in the axial direction. The fire-retardant filler in the fire-retardant strip can flow towards a fire-catching area and gradually gather in the fire-catching area to form a relatively thick fire-retardant barrier, and compared with an existing fixed spraying mode, the movable fire-retardant filler can gather from a non-fire-catching area to the fire-catching area and form a thicker barrier in an area needing fire-retardant, so that a better fire-retardant effect is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of electric wires and cables, and in particular to an environmentally friendly, high-temperature-resistant and fire-proof special cable and a preparation method thereof. Background Art

[0002] Fireproof special cables are characterized by high temperature resistance, flame retardancy, and low smoke, and they play a vital role in fires. They can maintain the continuity of circuits, support key safety systems such as fire fighting equipment, emergency lighting, alarm systems, and evacuation instructions, and buy precious time for personnel evacuation and fire rescue. At the same time, fireproof cables can also reduce the damage to electrical systems caused by fires and reduce the economic losses caused by fires.

[0003] The fire-retardant expansion material in the fire-resistant cable is a key fire-proof safety material. It can expand rapidly when a fire occurs to form a dense fire barrier, effectively preventing the spread of fire and smoke. At present, this type of material is usually sprayed or filled into the outer sheath or layered structure. When a fire occurs, only the material in the local area in contact with the flame will expand, and the rest of the fire-retardant material will not play a role. Although it plays a barrier role to a certain extent, the protection time is relatively short due to the limited thickness of the fire barrier it forms (generally a few millimeters to more than ten millimeters). Summary of the invention

[0004] In view of the defects of the prior art, the first aspect of the present invention provides an environmentally friendly, high temperature resistant and fireproof special cable, comprising:

[0005] The cable core comprises a conductor core and a filling rope twisted together, and the conductor core and the filling rope are wrapped by a composite wrapping layer to form a cable core with a circular cross section;

[0006] A shielding layer, braided and coated on the outside of the composite wrapping layer;

[0007] An outer sheath is extruded and coated on the outer side of the shielding layer;

[0008] The conductor core comprises a plurality of mutually twisted conductors and a first insulating layer and a second insulating layer covering the outside of the conductors from the inside to the outside, a through hole is opened in the second insulating layer along the axial direction, a fire barrier strip is arranged in the through hole, the fire barrier strip is filled with a fire barrier filler, and the fire barrier filler can move in the axial direction in the fire barrier strip.

[0009] Preferably, the fire barrier strip is provided with a plurality of adhesive sections along the length direction, a cavity is provided between any two adjacent adhesive sections, both ends of the cavity are sealed by the adhesive sections, and each cavity is filled with the fire barrier filler.

[0010] Preferably, the fire-retardant filling accounts for between 1 / 2 and 2 / 3 in each cavity.

[0011] Preferably, the distance between any two adjacent bonding sections is set to 50CM to 100CM.

[0012] Preferably, the fire-retardant filling is a fire-retardant expansion filling paste, and the space in the cavity other than the fire-retardant filling is filled with carbon dioxide or air.

[0013] Preferably, a protruding portion is provided on the outer side wall of the second insulating layer, and the protruding portions on any two adjacent second insulating layers are located at the twisting center.

[0014] Preferably, the number of the fire-blocking strips distributed on one side of the second insulating layer close to the protrusion is less than the number of the fire-blocking strips distributed on the other side.

[0015] Preferably, the filling rope comprises glass fiber rope or mineral fiber rope.

[0016] Preferably, the composite wrapping layer comprises a heat insulation wrapping layer and a heat radiation isolation layer wrapped sequentially from the inside to the outside, and the wrapping directions of the heat insulation wrapping layer and the heat radiation isolation layer are opposite.

[0017] Preferably, the thermal insulation wrapping layer comprises a mica wrapping tape, and the thermal radiation isolation layer comprises aluminum foil or aluminum-plated foil.

[0018] A second aspect of the present invention provides a method for preparing an environmentally friendly, high temperature resistant and fireproof special cable, comprising the following steps:

[0019] Step 1: Prepare the cable core:

[0020] Step 1.1, preparing a conductor core: using a stranding machine to twist a plurality of wires together to form a conductor, arranging the conductor and a plurality of fire barrier strips according to preset positions, and using an extruder to extrude a first insulating layer and a second insulating layer on the outer side of the conductor and the fire barrier strip in a double-layer co-extrusion manner to form a conductor core;

[0021] Step 1.2, preparing the filling rope: using a braiding machine to weave glass fiber or mineral fiber into a rope body;

[0022] Step 1.3, wrapping into cable: twisting the prepared conductor cores together, filling the gap outside the conductor cores with filling ropes, wrapping a heat insulation wrapping layer forwardly on the outside of the conductor cores and the filling ropes, and then wrapping a heat radiation isolation layer reversely on the outside of the heat insulation wrapping layer to form a cable core with a circular cross-section, wherein the heat insulation wrapping layer and the heat radiation isolation layer form a composite wrapping layer;

[0023] Step 2, preparing a shielding layer: using a braiding machine to weave a copper mesh on the outside of the composite wrapping layer, and making the braiding density of the copper mesh greater than 85%, to form a shielding layer on the outside of the composite wrapping layer;

[0024] Step 3, preparing an outer sheath: using an extruder to extrude an insulating material to cover the outer side of the shielding layer to form an outer sheath;

[0025] In step 1.1, the fire-retardant strip is preliminarily formed into a hollow tube by an extruder. After the tube is formed, a fire-retardant filler and a gas are periodically and quantitatively filled into the tube. After the fire-retardant filler is filled in each cycle, the tube is extruded according to a preset length to form a bonding section on the tube, and the filled fire-retardant filler and gas are sealed in the tube to form the fire-retardant strip.

[0026] Compared with the prior art, the environmentally friendly, high temperature resistant and fireproof special cable of the present invention has the following significant advantages:

[0027] The environmentally friendly, high-temperature resistant and fireproof special cable of the present invention is provided with a fire-blocking strip in the second insulating layer. When a part of the area is burned through, the fire-blocking filler in the fire-blocking strip will flow toward the fire area, and gradually gather in the fire area to form a relatively thick fire-blocking barrier. Compared with the existing fixed spraying method, the movable fire-blocking filler can gather from the non-fire area to the fire area, forming a thicker barrier in the area where fire blocking is required, thereby achieving a better fire-blocking effect, and buying more time for emergency disposal and evacuation when fire / danger occurs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are not intended to be drawn to scale. In the accompanying drawings, each identical or nearly identical component shown in each figure may be represented by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings.

[0029] Figure 1 It is a schematic diagram of the hierarchical structure of the environmentally friendly, high temperature resistant and fireproof special cable shown in an embodiment of the present invention.

[0030] Figure 2 It is a schematic diagram of the cross-sectional structure of an environmentally friendly, high-temperature-resistant and fire-resistant special cable shown in an embodiment of the present invention.

[0031] Figure 3 It is a schematic diagram of the enlarged cross-section structure of the conductor core in the environmentally friendly, high-temperature-resistant and fire-proof special cable shown in an embodiment of the present invention.

[0032] Figure 4 It is a schematic diagram of the partial structure of the fire barrier strip in the environmentally friendly, high temperature resistant and fireproof special cable shown in an embodiment of the present invention.

[0033] The definitions of the various symbols in the accompanying drawings are as follows:

[0034] 10. Conductor core; 11. Conductor; 12. First insulating layer; 13. Second insulating layer; 131. Protrusion; 14. Fire barrier strip; 140. Cavity; 141. Adhesive section; 142. Fire barrier filling; 20. Filling rope; 30. Composite wrapping layer; 31. Thermal insulation wrapping layer; 32. Thermal radiation isolation layer; 40. Shielding layer; 50. Outer sheath. DETAILED DESCRIPTION

[0035] In order to better understand the technical content of the present invention, specific embodiments are given and described as follows in conjunction with the accompanying drawings.

[0036] like Figure 1-Figure 4 As shown, the present invention provides an environmentally friendly, high temperature resistant and fireproof special cable, which aims to improve the isolation effect of the fire-retardant expansion material when a fire occurs. The cable includes a cable core, a shielding layer 40 and an outer sheath 50.

[0037] like Figure 2 In the example shown, the cable core includes a conductor core 10 and a filling rope 20 twisted together, and the conductor core 10 and the filling rope 20 are wrapped by a composite wrapping layer 30 to form a cable core with a circular cross section.

[0038] Further, such as Figure 1 and Figure 3 As shown, the conductor core 10 includes a plurality of mutually twisted conductors 11 and a first insulating layer 12 and a second insulating layer 13 which are wrapped around the outside of the conductors 11 from the inside to the outside. A through hole is provided in the second insulating layer 13 along the axial direction, a fire barrier strip 14 is provided in the through hole, and the fire barrier strip 14 is filled with a fire barrier filler 142, and the fire barrier filler 142 can move in the axial direction in the fire barrier strip 14.

[0039] In some embodiments, the wire 11 is made of annealed oxygen-free fine copper wire twisted in a regular twisting manner of 1+6+12+18 to form a conductor, and the first insulating layer 12 and the second insulating layer 13 on the outside are extruded and coated on the outside of the conductor using an extruder in a double-layer co-extrusion process, wherein the inner first insulating layer 12 is cross-linked polyethylene or silane cross-linked polyethylene, which has good electrical properties, mechanical properties and heat resistance, and can withstand higher operating temperatures and voltage levels; the outer second insulating layer 13 is made of flame-retardant polyethylene PVC or silicone rubber, and a through hole is formed during the extrusion process to facilitate the extrusion molding of the inner fire barrier strip 14.

[0040] like Figure 3 and Figure 4 As shown, the fire barrier strip 14 is provided with a plurality of adhesive sections 141 along the length direction, and a cavity 140 is provided between any two adjacent adhesive sections 141 . Both ends of the cavity 140 are sealed by the adhesive sections 141 , and each cavity 140 is filled with a fire barrier filling 142 .

[0041] In some embodiments, the fire barrier strip 14 is quantitatively filled with fire barrier filling 142 during the extrusion process, and is pressed together at a certain distance to form bonding sections 141, thereby sealing the area filled with the fire barrier filling 142. In this way, when a part of the area is burned through, the fire barrier filling 142 in the fire barrier strip 14 will flow toward the fire area, and gradually gather in the fire area to form a relatively thick fire barrier. Compared with the existing fixed spraying method, the movable fire barrier filling 142 can gather from the non-fire area to the fire area, forming a thicker barrier in the area where fire barrier is required, thereby achieving a better fire barrier effect.

[0042] Preferably, the fire-retardant filling 142 accounts for between 1 / 2 and 2 / 3 in each cavity 140, wherein the fire-retardant filling 142 can be made of a fire-retardant expansion filling paste, such as an expandable graphite paste filled with a flame retardant, and the space in the cavity 140 other than the fire-retardant filling 142 is filled with carbon dioxide or air.

[0043] In some embodiments, the fire-retardant filling 142 can also adopt liquid or powdered fire-retardant expansion material, wherein the shape of the material is related to the added substrate, and its fire-retardant expansion performance mainly depends on the fire retardant and expansion agent added inside. The shape of the fire-retardant filling 142 is determined according to the use requirements, wherein the paste and liquid fillers have relatively good fluidity, and can be squeezed out from the defect under the expansion of internal gas pressure. It should be understood that the gas filled in the cavity 140 is not limited to air or carbon dioxide. For example, carbon dioxide is not only not easy to oxidize the internal filling material, but also can expand and squeeze the fire-retardant expansion material in the cavity 140 under high temperature environment, thereby promoting the discharge of the fire-retardant expansion material, and at the same time can reduce the oxygen content in the area, which is beneficial to reduce the fire.

[0044] In this way, under high external temperature, the air or carbon dioxide in the cavity 140 will expand under pressure. When the fire barrier strip 14 is damaged, the gas pressure will squeeze the fire barrier filling 142 inside the cavity 140 outward, so that the fire barrier filling 142 can gather from the non-fire area to the fire area.

[0045] Optionally, the distance between any two adjacent adhesive sections 141 is set to 50CM to 100CM, so that multiple independent fire-blocking sections can be formed on the fire-blocking strip 14, so that the gas inside the cavity 140 has sufficient pressure after expansion to promote the flow of the fire-blocking filling 142.

[0046] In some embodiments, the positions of the adhesive sections 141 on two adjacent fire barrier strips 14 can be staggered in the axial direction. In this way, the portion of the fire barrier strip 14 filled with fire barrier material can cover the entire cable in the axial direction, thereby preventing the fire barrier material from being unable to accumulate in that portion due to the aggregation of the adhesive sections 141.

[0047] like Figure 3 As shown, a protruding protrusion 131 is provided on the outer wall of the second insulating layer 13, and the protrusions 131 on any two adjacent second insulating layers 13 are at the twisting center. Taking three groups of conductors twisted in the cable core as an example, the angle of the protrusion 131 is set to one hundred and twenty degrees. When the three groups of conductors are twisted, the middle parts fit together and the strength is higher.

[0048] Furthermore, the number of fire-retardant strips 14 distributed on one side of the protrusion 131 in the second insulating layer 13 is smaller than the number of fire-retardant strips 14 distributed on the other side. If a fire occurs, the outer area of ​​the insulating layer will first come into contact with the flame, so the number of fire-retardant strips 14 arranged is greater than that of the inner layer.

[0049] It should be understood that in some embodiments, the fire barrier strip 14 is not limited to the second insulating layer 13. It is intended to gather the internal movable fire barrier filling 142 from the non-fire area to the fire area, forming a thicker barrier in the area where fire barrier is required, thereby achieving a better fire barrier effect.

[0050] Thus, in some embodiments, the fire barrier strip 14 can also be arranged between the hierarchical structures, or the fire barrier strip 14 and the filling rope 20 can be filled together in the gap between the guide cores 10. At the same time, the shape of the fire barrier strip 14 is not limited to a thin tube. According to the needs, the fire barrier strip 14 can also be set to a fan-shaped, rectangular or hollow ring-shaped shape, wherein the fan-shaped and rectangular shapes have a larger coverage in the circumferential direction than the thin tube, and the hollow ring shape is directly coated on the circumferential side of the cable core, and its coverage is larger. In this way, when the fire barrier strip 14 is burned through by flame or high temperature, it can still extrude the expandable flame retardant outward from the burned-through position, so that the expandable flame retardant forms a thicker flame retardant barrier layer at the fire site.

[0051] Optionally, the filling rope 20 is made of glass fiber rope or mineral fiber rope, which has good flame retardant effect.

[0052] like Figure 1 As shown, further, the composite wrapping layer 30 includes a heat insulation wrapping layer 31 and a heat radiation isolation layer 32 wrapped sequentially from the inside to the outside, and the wrapping directions of the heat insulation wrapping layer 31 and the heat radiation isolation layer 32 are opposite.

[0053] Among them, the thermal insulation wrapping layer 31 includes a mica wrapping tape, and the thermal radiation isolation layer 32 includes an aluminum foil or an aluminum-plated foil. In this way, the inner mica wrapping tape can play a fire-proof and isolating role, while the outer aluminum foil or an aluminum-plated foil can reflect thermal radiation. When a fire occurs, the temperature of the inner conductor can be reduced.

[0054] Furthermore, the shielding layer 40 is braided and coated on the outside of the composite wrapping layer 30 , and is formed by braiding fine copper wires with a diameter of less than 0.5 mm, and the braiding density is greater than 90%.

[0055] The outer sheath 50 is extruded and coated on the outside of the shielding layer 40, and is made of low-smoke halogen-free polyolefin sheath material, which has good insulation, flame retardancy, corrosion resistance and protection, and can effectively reduce the toxic gas and smoke generated during a fire, reducing the impact on personnel and the environment.

[0056] In combination with the fireproof cable design of the above embodiment, by arranging a fire barrier strip 14 in the second insulating layer 13, when a part of the area is burned through, the fire barrier filling 142 in the fire barrier strip 14 will flow toward the fire area, and gradually gather in the fire area to form a relatively thick fire barrier. Compared with the existing fixed spraying method, the movable fire barrier filling 142 can gather from the non-fire area to the fire area, forming a thicker barrier in the area where fire barrier is required, thereby achieving a better fire barrier effect.

[0057] A second aspect of the present invention provides a method for preparing an environmentally friendly, high temperature resistant and fireproof special cable, comprising the following steps:

[0058] Step 1: Prepare the cable core:

[0059] Step 1.1, preparing the conductor core 10: using a stranding machine to anneal oxygen-free thin copper wires in a regular stranding method of 1+6+12+18 to form a conductor, arranging the conductor and a plurality of fire barrier strips 14 according to preset positions, and using an extruder to extrude a first insulating layer 12 and a second insulating layer 13 on the outer side of the conductor and the fire barrier strips 14 in a double-layer co-extrusion manner to form the conductor core 10;

[0060] Step 1.2, preparing the filling rope 20: using a braiding machine to braid the glass fiber or mineral fiber into a rope body for later use;

[0061] Step 1.3, wrapping into cable: twisting the prepared conductor cores 10 together, filling the gap outside the conductor core 10 with a filling rope 20, wrapping mica tape on the outside of the conductor core 10 and the filling rope 20 in a forward direction to form a heat insulation wrapping layer 31, and then wrapping aluminum foil or aluminum-plated foil on the outside of the heat insulation wrapping layer 31 in a reverse direction to form a heat radiation isolation layer 32 to form a cable core with a circular cross-section, and the heat insulation wrapping layer 31 and the heat radiation isolation layer 32 form a composite wrapping layer 30;

[0062] Step 2, preparing the shielding layer 40: using a braiding machine to weave a copper mesh on the outside of the composite wrapping layer 30, and making the weaving density of the copper mesh greater than 85%, so as to form the shielding layer 40 on the outside of the composite wrapping layer 30;

[0063] Step 3, preparing the outer sheath 50: using an extruder to extrude an insulating material to cover the outer side of the shielding layer 40 to form the outer sheath 50;

[0064] In step 1.1, the fire-retardant strip 14 is preliminarily formed into a hollow tube by an extruder. After the tube is formed, the fire-retardant filler 142 and gas are periodically and quantitatively filled into the tube. After the fire-retardant filler 142 is filled in each cycle, the tube is extruded according to a preset length to form a bonding section 141 on the tube, and the filled fire-retardant filler 142 and gas are sealed in the tube to form the fire-retardant strip 14.

[0065] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims

1. An environmentally friendly, high temperature resistant and fireproof special cable, characterized in that: include: The cable core comprises a conductor core (10) and a filling rope (20) twisted together, and the conductor core (10) and the filling rope (20) are wrapped by a composite wrapping layer (30) to form a cable core with a circular cross section; A shielding layer (40) braided and coated on the outside of the composite wrapping layer (30); An outer sheath (50) is extruded and coated on the outer side of the shielding layer (40); The conductor core (10) comprises a plurality of mutually twisted conductors (11), and a first insulating layer (12) and a second insulating layer (13) which are coated on the outside of the conductors (11) from the inside to the outside, a through hole is provided in the second insulating layer (13) along the axial direction, a fire barrier strip (14) is provided in the through hole, the fire barrier strip (14) is filled with a fire barrier filler (142), and the fire barrier filler (142) can move in the axial direction in the fire barrier strip (14); The fire barrier strip (14) is provided with a plurality of adhesive sections (141) along the length direction, a cavity (140) is provided between any two adjacent adhesive sections (141), both ends of the cavity (140) are sealed by the adhesive sections (141), and each cavity (140) is filled with the fire barrier filling (142).

2. The environmentally friendly, high temperature resistant and fireproof special cable according to claim 1 is characterized in that: The proportion of the fire-retardant filling (142) in each cavity (140) is between 1 / 2 and 2 / 3.

3. The environmentally friendly, high temperature resistant and fireproof special cable according to claim 1 is characterized in that: The distance between any two adjacent bonding sections (141) is set to 50CM to 100CM.

4. The environmentally friendly, high temperature resistant and fireproof special cable according to claim 1 is characterized in that: The fire-retardant filler (142) is a fire-retardant expansion filling paste, and the space of the cavity (140) other than the fire-retardant filler (142) is filled with carbon dioxide or air.

5. The environmentally friendly, high temperature resistant and fireproof special cable according to any one of claims 1 to 4, characterized in that: A protruding protrusion (131) is provided on the outer side wall of the second insulating layer (13), and the protrusions (131) on any two adjacent second insulating layers (13) are located at the twisting center.

6. The environmentally friendly, high temperature resistant and fireproof special cable according to claim 5, characterized in that: The number of the fire-retardant strips (14) distributed on one side of the second insulating layer (13) close to the protruding portion (131) is smaller than the number of the fire-retardant strips (14) distributed on the other side.

7. The environmentally friendly, high temperature resistant and fireproof special cable according to claim 5, characterized in that: The filling rope (20) comprises glass fiber rope or mineral fiber rope.

8. The environmentally friendly, high temperature resistant and fireproof special cable according to claim 5, characterized in that: The composite wrapping layer (30) comprises a heat insulation wrapping layer (31) and a heat radiation isolation layer (32) which are wrapped sequentially from the inside to the outside, and the wrapping directions of the heat insulation wrapping layer (31) and the heat radiation isolation layer (32) are opposite.

9. The environmentally friendly, high temperature resistant and fireproof special cable according to claim 8, characterized in that: The heat insulation wrapping layer (31) comprises a mica wrapping tape, and the heat radiation isolation layer (32) comprises aluminum foil or aluminum-plated foil.

10. The method for preparing the environmentally friendly, high temperature resistant and fireproof special cable according to claim 1, characterized in that: The following steps are involved: Step 1: Prepare the cable core: Step 1.1, preparing a conductor core (10): using a twisting machine to twist a plurality of conductors (11) to form a conductor, arranging the conductor and a plurality of fire barrier strips (14) according to a preset position, and using an extruder to extrude a first insulating layer (12) and a second insulating layer (13) on the outer side of the conductor and the fire barrier strip (14) in a double-layer co-extrusion manner to form a conductor core (10); Step 1.2, preparing a filling rope (20): using a braiding machine to braid glass fibers or mineral fibers into a rope body; Step 1.3, wrapping into a cable: twisting the prepared conductor cores (10) together, filling the gap outside the conductor core (10) with a filling rope (20), wrapping a heat insulating wrapping layer (31) forwardly on the outside of the conductor core (10) and the filling rope (20), and then wrapping a heat radiation isolation layer (32) reversely on the outside of the heat insulating wrapping layer (31) to form a cable core with a circular cross-section, wherein the heat insulating wrapping layer (31) and the heat radiation isolation layer (32) form a composite wrapping layer (30); Step 2, preparing a shielding layer (40): using a braiding machine to braid a copper mesh on the outside of the composite wrapping layer (30), and making the braiding density of the copper mesh greater than 85%, so as to form a shielding layer (40) on the outside of the composite wrapping layer (30); Step 3, preparing an outer sheath (50): using an extruder to extrude an insulating material to cover the outer side of the shielding layer (40) to form an outer sheath (50); In step 1.1, the fire-retardant strip (14) is preliminarily formed into a hollow tube by an extruder. After the tube is formed, a fire-retardant filler (142) and a gas are periodically and quantitatively filled into the tube. After the fire-retardant filler (142) is filled in each cycle, the tube is extruded according to a preset length to form a bonding section (141) on the tube, and the filled fire-retardant filler (142) and the gas are sealed in the tube to form the fire-retardant strip (14).

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