Reinforced flexible PTC characteristic electric heating wire and preparation method thereof

Abstract

The invention discloses a reinforced flexible PTC characteristic electric heating wire, which comprises a flexible filling core, a conductive wire core, a contact resistance transition layer and a composite insulating layer, a PTC material layer is arranged among the conductive wire core, the contact resistance transition layer and the composite insulating layer; and the PTC material layer and the composite insulating layer are fused into a whole. By adopting the technical scheme, the performance of the electric heating wire and the electric heating device is improved; the elliptical cross section improves the conductivity of the product, reduces the consumption of the conductive material in the PTC core belt, and reduces the cost. The flexibility of the electric heating wire is improved; the tensile strength of the product is enhanced; the PTC material is better in contact, more stable in performance and capable of resisting bending for thousands of times; the head and tail ends of the insulating layer are not shrunk during thermal expansion and cold contraction, so that the product is safer, and the hidden danger of electric leakage is eliminated; by adopting left and right marks, the application of the electric heating device is safer, and a shielding layer is not needed for grounding protection; the product structure and the manufacturing process are simplified, and the integration level is improved; and the application range is wider.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrothermal devices. More specifically, the present invention relates to an electrothermal wire with enhanced flexible PTC characteristics. The present invention also relates to a preparation method of the electrothermal wire. Background Art

[0002] In the prior art, the structure of the electrothermal wire is as Figure 3 shown:

[0003] 1. Appearance: The core tape is in a flat or dumbbell-shaped strip.

[0004] 2. Structure: Reinforcing sheath, shielding layer, insulating layer, PTC core tape, conductive wire core (regular stranding and round or flat tubular braiding).

[0005] Its heating element is a special or ordinary "PTC" conductive polymer nanocomposite with a "PTC" effect (positive temperature coefficient effect of resistance) extruded between two parallel conductive wire cores to form a strip-shaped device. The heating element can automatically adjust the output power with the change of temperature. When the temperature rises to a certain temperature, its resistance tends to infinity and the output power is approximately zero, and vice versa. Therefore, it has good memory characteristics and switching characteristics. It is composed of a conductive wire core, PTC material, insulating layer, shielding layer, and reinforcing layer. The conductive wire core is made of multiple strands of stranding or multiple strands of braiding. The cross-section of the core tape is flat or dumbbell-shaped, and the temperature grades are divided into low, medium, and high temperatures. The main uses are pipeline tracing and heat preservation and ordinary building life implementation.

[0006] However, the problems and defects of the above prior art are: low flexibility, tensile strength, and bending strength; poor electrical conductivity; low integration, resulting in high product cost; and it is not easy to distinguish the polarity of the wire. Therefore, the prior art cannot be applied to flexible electrothermal devices.

[0007] Using keywords such as "PTC; electrothermal; wire; insulation; composite", the following retrieval results are obtained by retrieving the existing publicly available technical literature:

[0008] 1. Chinese patent document: "PTC polymer conductive composite self-limiting temperature heating tape and its preparation method", patent (application) number: 201210023244.2; the technical solution recorded therein is:

[0009] "The PTC polymer conductive composite self-limiting temperature heating tape includes a flat tape body. The tape body includes a polyethylene-based PTC conductive composite layer. Two conductive core wires are extruded inside the polyethylene-based PTC conductive composite layer. A circumferentially closed polyethylene insulating layer, a shielding layer, and a polyethylene reinforced protective layer are sequentially arranged outside the polyethylene-based PTC conductive composite layer from the inside to the outside. The present invention also discloses a preparation method of the self-limiting temperature heating tape, including preparing the polyethylene-based PTC conductive composite layer, extruding and arranging two conductive core wires, and then sequentially arranging a circumferentially closed polyethylene insulating layer, a shielding layer, and a polyethylene reinforced protective layer outside the polyethylene-based PTC conductive composite layer from the inside to the outside";

[0010] The recorded technical effects are:

[0011] "No bubbles will be generated during the operation of this heating tape, and its electrothermal performance is stable, safe and reliable; the preparation method has a simple process flow, low cost, and is easy to implement."

[0012] 2. Chinese patent document: "An electrothermal element for a cabinet air conditioner with PTC characteristics", patent (application) number: 201120492216.6; the recorded technical solution is:

[0013] "The electrothermal element for a cabinet air conditioner with PTC characteristics has a U-shaped or M-shaped structure, and it includes a U-shaped or M-shaped tube shell and a heating wire. The heating wire is a PTC heating wire, which is arranged inside the U-shaped or M-shaped tube shell and extends along the tube axis. A high-temperature resistant insulating layer is filled between the heating wire and the tube shell. The U-shaped or M-shaped tube shell is a U-shaped or M-shaped metal tube, and the PTC heating wire inside it extends in a spiral shape";

[0014] The recorded technical effects are:

[0015] "Due to the use of the PTC heating wire, the threat to the components around the electrothermal element and the whole machine can be reduced, and the purpose of improving safety can be achieved."

[0016] However, the technical solutions recorded in the above technical documents, as well as the related technical solutions publicly applied in the existing technology, have not been able to solve the problems and defects such as "insufficient flexibility, strength, and conductivity", "low integration and high cost" existing in the existing technology. Summary of the Invention

[0017] The present invention provides an enhanced flexible PTC characteristic electric heating wire, the purpose of which is to improve the conductivity of the product, enhance excellent PTC characteristics, increase the number of bending times, making it up to thousands of times; reduce the consumption of conductive materials in the PTC core tape and reduce costs.

[0018] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0019] The enhanced flexible PTC characteristic heating wire of the present invention includes a flexible filling core, a conductive wire core, a contact resistance transition layer, and a composite insulating layer; a PTC material layer is provided between the conductive wire core, the contact resistance transition layer, and the composite insulating layer; the PTC material layer and the composite insulating layer are fused into one body.

[0020] The cross-sectional shape of the enhanced flexible PTC characteristic heating wire is oval.

[0021] The conductive wire core is tubular; the flexible filling core is arranged in the core part of the tubular.

[0022] The flexible filling core is a multi-strand non-metal wire or metal wire.

[0023] The conductive wire core and the flexible filling core form a flexible enhanced braided conductive wire core; the flexible enhanced braided conductive wire core is composed of multiple tinned copper wires braided on the outer surface of the flexible filling core to form a conductor with a circular or flat cross-section, high tensile strength, and high bending strength.

[0024] The contact resistance transition layer and the PTC material layer are arranged on the outer cylindrical surface of the conductive wire core to form a heating core strip.

[0025] On the outer surface of the composite insulating layer, left and right marking lines are provided, and their colors are significantly different from the color of the composite insulating layer.

[0026] The enhanced flexible PTC characteristic heating wire obtains rated grades of multiple voltages and multiple temperatures by changing the material composition ratio of different conductive wire cores, PTC material layers, and composite insulating layers; and the multiple voltages and multiple temperatures are respectively combined in different ways; the multiple voltages are respectively: 3V - 12V; 24 - 48; the multiple temperatures are respectively: starting from 20°C, each 10°C is a grade, that is: 20 - 30°C, 30 - 40°C, 40 - 50°C, up to 100 - 110°C.

[0027] In order to achieve the same invention purpose as the above technical solution, the present invention also provides a preparation method of the enhanced flexible PTC characteristic heating wire described above, and its technical solution is:

[0028] Adopt a multi-layer co-extrusion process and corresponding tooling and molds, and continuously complete the processes of extrusion coating of the contact resistance transition layer on the conductive wire core, extrusion coating of the PTC material layer and the composite insulating layer on the heating core strip, and injection coating of the left and right color separation marking lines through a production line and multiple molds;

[0029] The production line process of the preparation method is:

[0030] 1) Start the production line;

[0031] 2) Two conductive wire cores are arranged side by side on the pay-off reel to pay off the wire;

[0032] 3), The conductive wire core enters the wire core heating box for preheating;

[0033] 4), Double-layer co-extrusion is carried out on the core tape co-extruder: A contact resistance transition layer and a PTC material layer are extruded on the outer surfaces of two parallel and spaced conductive wire cores to form a heating core tape;

[0034] 5), Double-layer co-extrusion is carried out on the insulation layer co-extruder: A composite insulation layer is extruded on the outer surface of the heating core tape, and left and right identification lines are injection-coated on the outer surface of the composite insulation layer;

[0035] 6), The preparation of the enhanced flexible PTC characteristic heating wire is completed.

[0036] The present invention adopts the above technical solutions, improves the performance of the heating wire and the heating device, reduces the installation groove of the heating device, and can even be set more freely; The oval cross-section improves the conductivity of the product, reduces the consumption of conductive materials in the PTC core tape, and reduces costs; It improves the flexibility of the heating wire and enhances the tensile strength of the product; It makes the contact of the PTC material better, the performance more stable, and the number of bending resistance can be as high as thousands of times; When the product expands and contracts due to heat and cold, the insulation layer at the head and tail still does not shrink and is safer, eliminating the hidden danger of electric leakage; By adopting left and right identification, the application of the heating device is safer, and it can meet the national standard that flexible electric heating equipment does not require a grounding wire, so there is no need for a shielding layer for grounding protection; The product structure and manufacturing process are simplified, and the integration degree is improved; The application range is wider. Brief Description of the Drawings

[0037] The content shown in the drawings and the marks in the figures are briefly described as follows:

[0038] Figure 1 is the structural schematic diagram of the present invention;

[0039] Figure 2 is Figure 1 the cross-sectional schematic diagram of the shown structure;

[0040] Figure 3 is the structural schematic diagram of the prior art.

[0041] Figure 1 and Figure 2 The marks in are:

[0042] 1, Flexible filling core, 2, Conductive wire core, 3, Contact resistance transition layer, 4, PTC material layer, 5, Composite insulation layer, 6, Left and right identification lines. Detailed Embodiments

[0043] The following will further describe the specific embodiments of the present invention in detail with reference to the accompanying drawings through the description of the embodiments, so as to help those skilled in the art have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention.

[0044] As Figure 1 shown in the structure of the present invention, it is a flexible PTC characteristic electric heating wire, including a flexible filling core 1, a conductive wire core 2, a contact resistance transition layer 3 and a composite insulation layer 5. This product of the present invention can be used in living facilities, especially suitable for flexible electric blankets, etc., and can also be used in fields such as heat tracing and heat preservation.

[0045] The described contact resistance transition layer 3 is a transition functional layer with good contact resistance performance that is extruded and embedded in the braided layer.

[0046] The variable power electric heating wire of the present invention is used for electric blankets, especially for electric heating pads for infants and young children and health care for the elderly, as well as safe and reliable constant temperature flexible electric heating pads. Its temperature grades can be low and medium temperatures, with a total of 10 levels, multi-stage low voltage and photovoltaic direct drive, and can also be used with 220V general purpose.

[0047] In order to solve the problems existing in the prior art and overcome its defects, and achieve the invention purpose of improving the conductivity of the product, bending resistance, reducing the consumption of conductive materials in the PTC core belt, and reducing costs, the technical solution adopted by the present invention is:

[0048] As Figure 1 shown, in the flexible PTC characteristic electric heating wire of the present invention, a PTC material layer 4 is provided between the conductive wire core 2, the contact resistance transition layer 3 and the composite insulation layer 5; the PTC material layer 4 and the composite insulation layer 5 are melted into one body. Its safety performance is greatly improved, and the composite insulation does not shrink under hot and cold conditions.

[0049] The intelligent strip-shaped electric heating device of the present invention has a heating element that is a special or ordinary "PTC" conductive polymer nanocomposite with a "PTC" effect (positive temperature coefficient of resistance effect), and is extruded into a strip-shaped (or linear, plate-shaped) device formed between two parallel conductive wire cores. This heating element can automatically adjust the output power with the change of temperature. When the temperature rises to a certain temperature, its resistance tends to infinity and the output power is approximately zero, and vice versa, so it has good memory characteristics and switching characteristics.

[0050] The composite insulation layer 5 and the PTC material layer 4 are melted into one body, which is beneficial for not separating after thermal expansion and contraction, greatly improving the safety performance, and there is no need to add grounding and leakage protection.

[0051] The cross-sectional shape of the enhanced flexible PTC characteristic electric heating wire is oval.

[0052] The present invention is an improvement and innovation of the existing ribbon-shaped flat or dumbbell-shaped electric heating tape into a linear elliptical electric heating wire. After the improvement, it is beneficial to the reciprocating winding effectiveness between the electric heating wire and the electric heating device, and to reducing the installation groove of the electric heating device, etc. The elliptical cross-section has been verified to improve the conductivity of the product, reduce the consumption of the conductive material in the PTC core tape, and lower the cost. Compared with the flat and dumbbell-shaped cross-section PTC core tapes, the elliptical cross-section is more superior in terms of bending resistance, reciprocating winding and various properties.

[0053] The present invention is composed of a conductive wire core 1, a PTC material layer, a composite insulation layer, a shielding layer, a strengthening layer, and non-metallic wires or filaments. The conductive wire core 1 is formed by stranding or braiding multiple tinned (or nickel-plated) copper wires, and the cross-section of the core tape is elliptical.

[0054] The specific analysis is as follows:

[0055] The said conductive wire core 2 is tubular; the flexible filling core 1 is arranged in the core part of the said tubular.

[0056] The said flexible filling core 1 is multiple strands of non-metallic wires or metal wires.

[0057] The tubular interior of the conductive wire core 2 is filled with multiple (strands) of non-metallic wires or filaments to enhance its flexibility; the number of bending resistance times can be as high as thousands of times.

[0058] The said conductive wire core 2 and the flexible filling core 1 form a flexible enhanced braided conductive wire core; the said flexible enhanced braided conductive wire core is formed by braiding multiple tinned copper wires on the outer surface of the flexible filling core 1 to form a conductor with a circular or flat cross-section, high tensile strength, and high bending strength.

[0059] The flexible enhanced braided conductive wire core 2 is formed by braiding a dozen or dozens of tinned copper wires on one or more non-metallic wires or filaments to form a circular or flat high tensile strength and multi-bending times enhanced flexible braided conductive wire core.

[0060] The said contact resistance transition layer 3 and PTC material layer 4 are arranged on the outer cylindrical surface of the conductive wire core 2 to form a heating core tape.

[0061] An extruded contact resistance transition layer 3 is provided outside the conductive wire core 2 to make it bond more firmly with the non-metallic filaments through the tubular braided layer and clamp between the braided wires, so that the PTC material has better contact, more stable performance, and higher bending resistance times, which can reach thousands of times.

[0062] A composite insulation layer 5 is arranged on the outer surface of the said PTC material layer 4.

[0063] A composite insulation layer 5 that is integrally heat-melted with the surface of the PTC core belt is used to replace the insulation layer with a common layered structure in the prior art, so that the head and tail ends of the insulation layer do not shrink during thermal expansion and contraction, making it safer and eliminating the potential leakage hazard; making the electric heating device safer without the need for a shielding layer for grounding protection.

[0064] The composite insulation layer 5 is a layer of insulation that cannot be peeled off and is integrated on the surface of the PTC core belt, solving the problem that the insulation layer material and the PTC layer have different thermal expansion and contraction ratios after being heated and cooled, resulting in damage to the insulation layer function and causing short circuits, thus enhancing the insulation performance.

[0065] On the outer surface of the composite insulation layer 5 described above, left and right marking lines 6 are provided, and their colors are significantly different from the color of the composite insulation layer 5. There are two-color marking lines on the composite insulation layer to directly distinguish the left and right two wires after reciprocating winding.

[0066] The present invention adopts the innovation of distinguishing left and right marking lines. General electric heating tapes do not distinguish left and right markings. However, due to the multiple reciprocating bends of the heating wires in the electric heater, it is impossible to simply and directly distinguish left and right, resulting in chaotic head and tail wiring and short circuits; while the present invention has left and right markings, making its application simple, direct, and meeting safety standards.

[0067] The present invention only needs a composite insulation layer to replace the three-layer structure of a common insulation layer + shielding layer + reinforcing layer, simplifying and integrating multiple functions of the product, and reducing costs.

[0068] The enhanced flexible PTC characteristic heating wire described above obtains rated levels of multiple voltages and multiple temperatures by changing the material composition ratio of different conductive wire cores 2, PTC material layers 4, and composite insulation layers 5; and the multiple voltages and multiple temperatures are respectively combined in different ways; the multiple voltages are respectively: 3V - 12V; 24 - 48; the multiple temperatures are respectively: starting from 20°C, each 10°C is a level, that is: 20 - 30°C, 30 - 40°C, 40 - 50°C, up to 100 - 110°C.

[0069] By changing the ratio of different material components and material changes, adjusting the multiple voltages, changing the material formula, and adjusting the multiple temperatures, 20 - 30 degrees, 30 - 40 degrees, 40 - 50 degrees, with a first-order difference of 10 degrees each, up to 110 degrees. Specifically:

[0070] 1. Combinations of the same material, different voltages, and different temperatures;

[0071] 2. Combinations of different materials, the same voltage, and different temperatures;

[0072] To adapt to the use of different working conditions, so as to achieve:

[0073] 1. Multi-level voltages: 3V - 12V; 24 - 48; 110 - 220V; multiple AC / DC conversions between wind / solar power and mains power; multiple wide-range AC / DC operating voltages of ±50%.

[0074] Multi-level temperature grades: 20 - 30°C, 30 - 40°C, 40 - 50°C, with a difference of 10 degrees per step up to 100 - 110°C.

[0075] 2. Wide-range operating voltage of ±50%, suitable for photovoltaic, wind power non-battery, non-inverter direct drive variable electric heating, and suitable for photovoltaic (wind power) direct drive electric heating applications in powerless areas.

[0076] In order to achieve the same invention purpose as the above technical solution, the present invention also provides a preparation method of the enhanced flexible PTC characteristic heating wire described above, and its technical solution is as follows:

[0077] In order to achieve the same invention purpose as the above technical solution, the present invention also provides a preparation method of the enhanced flexible PTC characteristic heating wire described above, and its technical solution is as follows:

[0078] Adopt a multi-layer co-extrusion process and corresponding tooling and molds, and continuously complete the processes of extrusion coating of the contact resistance transition layer 3 on the conductive wire core 2, extrusion coating of the PTC material layer 4 on the heating core tape, extrusion coating of the composite insulation layer 5, and injection coating of the left and right color-coded marking lines 6 through a production line and multiple molds;

[0079] The production line process of the described preparation method is as follows:

[0080] 1. Start the production line;

[0081] 2. Two conductive wire cores 2 are arranged side by side and pay off on the pay-off stand;

[0082] 3. The conductive wire core 2 enters the wire core preheating box for preheating;

[0083] 4. Perform double-layer co-extrusion on the core tape co-extruder: Extrusion coat the contact resistance transition layer 3 and the PTC material layer 4 on the outer surfaces of two parallel and spaced conductive wire cores 2 to form a heating core tape;

[0084] 5. Perform double-layer co-extrusion on the insulation layer co-extruder: Extrusion coat the composite insulation layer 5 on the outer surface of the heating core tape, and at the same time injection coat the left and right marking lines 6 on the outer surface of the composite insulation layer 5;

[0085] 6. The preparation of the enhanced flexible PTC characteristic heating wire is completed.

[0086] The preparation method of the enhanced flexible PTC characteristic heating wire adopts a multi-layer co-extrusion process and corresponding tooling and dies, and completes the heating wire product through a production line, including the double co-extrusion of the conductive wire core contact resistance transition layer and the core tape, the double co-extrusion of the composite insulation layer and the left and right color-coded marking lines, the vacuum drawing and wrapping of the double co-extrusion tube, four main machines, and two-section combined dies.

[0087] The present invention has been described exemplarily above in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited by the above-mentioned manner. As long as various non-substantive improvements are made by adopting the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. An enhanced flexible PTC characteristic electric heating wire, comprising a flexible filling core (1), a conductive wire core (2), a contact resistance transition layer (3) and a composite insulating layer (5), characterized in that: A PTC material layer (4) is provided between the conductive wire core (2), the contact resistance transition layer (3) and the composite insulating layer (5); the PTC material layer (4) and the composite insulating layer (5) are fused into one.

2. The enhanced flexible PTC characteristic heating wire according to claim 1, characterized in that: The cross-sectional shape of the enhanced flexible PTC characteristic electric heating wire is an ellipse.

3. The enhanced flexible PTC characteristic heating wire according to claim 1, characterized in that: The conductive wire core (2) is tubular; the flexible filling core (1) is arranged in the tubular core.

4. The enhanced flexible PTC characteristic heating wire according to claim 3, characterized in that: The flexible filling core (1) is a plurality of strands of non-metallic wires or metal wires.

5. The enhanced flexible PTC characteristic heating wire according to claim 4, characterized in that: The conductive wire core (2) and the flexible filling core (1) form a flexible reinforced braided conductive wire core; the flexible reinforced braided conductive wire core is composed of a plurality of tinned copper wires braided on the outer surface of the flexible filling core (1), forming a conductor with a circular or flat cross-section and high tensile strength and high bending strength.

6. The enhanced flexible PTC characteristic heating wire according to claim 1, characterized in that: The contact resistance transition layer (3) and the PTC material layer (4) are arranged on the outer cylindrical surface of the conductive wire core (2) to form a heating core belt.

7. The enhanced flexible PTC characteristic heating wire according to claim 1, characterized in that: Left and right identification lines (6) are arranged on the outer surface of the composite insulating layer (5), and the color of the left and right identification lines (6) is obviously different from the color of the composite insulating layer (5).

8. The enhanced flexible PTC characteristic heating wire according to claim 1, characterized in that: The enhanced flexible PTC characteristic electric heating wire obtains rated levels of multi-level voltage and multi-level temperature by changing the material component formula ratio of different conductive wire cores (2), PTC material layers (4) and composite insulation layers (5); and the multi-level voltage and multi-level temperature are respectively combined in different ways; the multi-level voltage is respectively: 3V to 12V; 24 to 48; the multi-level temperature is respectively: starting from 20°C, each 10°C is a level, that is: 20 to 30°C, 30 to 40°C, 40 to 50°C, up to 100 to 110°C.

9. The method for preparing an enhanced flexible PTC characteristic electric heating wire according to any one of claims 1 to 8, wherein a multi-layer co-extrusion process and corresponding tooling molds are used to continuously complete the steps of extruding a contact resistance transition layer (3) on the conductive wire core (2), extruding a PTC material layer (4) and a composite insulating layer (5) on the heating core strip, and coating the left and right color separation identification lines (6) through a production line and multiple molds; It is characterized in that The production line process of the preparation method is: 1) Production line start-up; 2) The two conductive wire cores (2) are laid out side by side on a wire pay-off frame; 3) The conductive wire core (2) enters the wire core heating box for preheating; 4) Performing double-layer co-extrusion on a core belt co-extruder: Extruding a contact resistance transition layer (3) and a PTC material layer (4) on the outer surfaces of two parallel and spaced conductive wire cores (2) to form a heating core belt; 5) Perform double-layer co-extrusion on an insulation layer co-extruder: extrude a composite insulation layer (5) on the outer surface of the heating core strip, and simultaneously inject left and right identification lines (6) on the outer surface of the composite insulation layer (5); 6) The preparation of the enhanced flexible PTC characteristic heating wire is completed.

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