A pipe heating and insulating composite tape and a preparation process thereof

Abstract

A kind of pipeline heating insulation composite tape and its preparation process, including nickel-chromium alloy foil, the outer side of nickel-chromium alloy foil is provided with first insulating heat-conducting adhesive layer, the outer side of first insulating heat-conducting adhesive layer is provided with glass fiber cloth, the outer side of glass fiber cloth is provided with foaming fire-retardant high-temperature-resistant rubber;The inner side of nickel-chromium alloy foil is provided with second insulating heat-conducting adhesive layer;The present application improves the conversion efficiency of electric heating, facilitates construction, and the construction cost is low;At the same time, the loss of heat transmission to the outside is reduced, and the heat preservation effect is achieved.

Description

Technical Field

[0001] This invention belongs to the technical field of composite tape for pipeline heating and insulation, specifically relating to a composite tape for pipeline heating and insulation and its preparation process. Background Technology

[0002] When the outside temperature drops to between 0°C and -10°C, liquids (water and other liquids) exposed in external pipes may freeze or condense. Simple methods such as pipe insulation, rinsing with hot water, or draining the pipes are usually used to prevent or resolve this. However, if the outside temperature is below -10°C, the liquids exposed in external pipes easily condense in the low temperatures, and even with insulation and antifreeze measures, it is difficult to achieve the desired effect. Once the liquid in the pipes condenses, it may burst and leak, leading to a lack of water supply. To restore normal operation, methods such as pouring hot water or heating the outer wall of the pipes are generally used as temporary solutions. Throughout the cold weather, the constant threat of frozen pipes severely impacts daily life and work.

[0003] Existing heat tracing cables used for pipeline heating, commonly referred to as electric heating cables (application number: CN201420398234, name: electric heating cable; application number: CN201210455070.7, name: a constant power electric heating cable), share the common feature of using conductive carbon paste to wrap two metal conductive wires, with an outer sheath of silicone rubber or engineering plastic composite material as insulation. These are wound around the outside of the pipeline, using the conductive carbon paste as the heat source and the two metal wires as conductors. Under certain voltage and current conditions, the material heats up to achieve the functions of cooling and insulation of the pipeline. Another type of heating tape (application number: CN201820566786.7, name: a glass fiber electric heating tape) is composed of heating materials and insulating materials. The heating material is a nickel-chromium alloy strip, and the insulating material is multi-layer alkali-free glass fiber. During use, the nickel-chromium alloy strip and the multi-layer alkali-free glass fiber are wound separately around the surface of the heated area to achieve cooling and insulation.

[0004] The aforementioned existing technologies have the following drawbacks: Using carbon paste as a heat source suffers from material aging, known in the industry as thermal decay, causing a rapid decrease in heating efficiency over time and inconveniencing users. Furthermore, this material lacks a heat conduction path within the heat source, resulting in low efficiency in converting electrical energy into heat. The outer surface of the heat source is an insulator, not a good one, leading to high operating costs. While using a nickel-chromium alloy strip as the heating source and alkali-free glass fiber as insulation overcomes the thermal decay problem, it still suffers from limitations due to the lack of a heat conduction path within the heat source and the absence of a good insulation on the outer surface. Additionally, the nickel-chromium alloy strip and alkali-free glass fiber are not integrated, requiring separate winding during installation, which is less convenient and faster than using carbon paste, resulting in higher construction costs. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a composite tape for pipeline heating and insulation and its preparation process, which improves the electrothermal conversion efficiency, facilitates construction, and reduces construction costs; at the same time, it reduces heat loss to the outside, thus achieving the effect of heat preservation and energy saving.

[0006] To achieve the above objectives, the present invention adopts the following solutions:

[0007] A composite tape for pipe heating and insulation includes a nickel-chromium alloy foil 1, a first insulating and thermally conductive adhesive layer 2 on the outer side of the nickel-chromium alloy foil 1, a glass fiber cloth 3 on the outer side of the first insulating and thermally conductive adhesive layer 2, and a foamed flame-retardant and high-temperature resistant rubber 4 on the outer side of the glass fiber cloth 3; and a second insulating and thermally conductive adhesive layer 5 on the inner side of the nickel-chromium alloy foil 1.

[0008] The nickel-chromium alloy foil 1 has a thickness of 0.05-0.1 mm.

[0009] The aforementioned composite tape for pipeline heating and insulation can be cut to any width from 20mm to 500mm as needed.

[0010] A manufacturing process for a composite heating and insulation strip for pipelines includes the following steps:

[0011] 1) A third insulating thermally conductive adhesive layer and a fourth insulating thermally conductive adhesive layer are coated on the outer side of the nickel-chromium alloy foil 1 and the inner side of the glass fiber cloth 3, respectively. The third insulating thermally conductive adhesive layer and the fourth insulating thermally conductive adhesive layer are modified insulating thermally conductive adhesives formed by mixing modified acrylic resin and modified thermally conductive filler powder, which are baked in a tunnel furnace to reach a gel state.

[0012] 2) Roll-press the third insulating thermally conductive adhesive layer on the outer side of the nickel-chromium alloy foil 1 and the fourth insulating thermally conductive adhesive layer on the inner side of the glass fiber cloth 3 to form the first insulating thermally conductive adhesive layer 2.

[0013] 3) Screen print the circuit diagram on the inner side of the nickel-chromium alloy foil 1 to achieve the set resistance value; after etching, clean it with water and dry it.

[0014] 4) A second insulating and thermally conductive adhesive layer 5 is coated on the circuit diagram of nickel-chromium alloy foil 1, and a layer of foamed flame-retardant and high-temperature resistant rubber 4 is coated on the outer side of glass fiber cloth 3.

[0015] In step 1), the thickness of the third and fourth insulating thermally conductive adhesive layers is 0.10-0.15 mm each.

[0016] The modified thermally conductive filler powder in step 1) is prepared as follows: silicon micro powder and alumina powder are prepared according to the mass ratio of silicon micro powder: alumina powder = 4:6. After the silicon micro powder and alumina powder are mixed evenly, KH-550 coupling agent accounting for 3-5% of the total mass of the mixture is added. The mixture is reacted at 110°C in a high-speed dispersion tank. After the reaction is complete in 3 hours, the temperature is lowered. When the temperature drops to 50°C, it is ready for use.

[0017] The modified acrylic resin is prepared by adding 12% (by weight) of bisphenol A type resin E-51 to acrylic acid T807, and then using 0.01-0.02% (by weight) of 2-methylimidazole as an initiator. The mixture is stirred uniformly at 90°C for 2-2.5 hours. When the viscosity of the reactants changes significantly, i.e. when the reactants are picked up with a glass rod, the reactants go from dripping downwards to forming a completely string-like shape, the reaction is stopped, and the mixture is cooled to room temperature before being stored for use.

[0018] Modified insulating and thermally conductive adhesive: Based on modified acrylic resin, 65-70% of its mass of modified thermally conductive filler powder is added. The modified thermally conductive filler and modified acrylic resin are mixed and stirred at high speed for 4-5 hours in a high-speed emulsifier. After cooling to room temperature by circulating water outside the emulsification tank, it is used.

[0019] The modified insulating and thermally conductive adhesive was coated onto nickel-chromium alloy foil 1 and glass fiber cloth 3 with a set thickness by roller coating and continuous baking. The temperature gradient was set from low, high, and medium: 90℃--110℃---130℃--160℃--140℃, and the speed was determined according to the gelation time. After coating, the adhesive was baked in an oven to a pre-cured gel state.

[0020] Step 2) Roller bonding is performed at a temperature of 150-170℃ and a pressure of 2 kg / cm². 2 The following will proceed.

[0021] In step 4), the coating of the second insulating and thermally conductive adhesive layer 5 specifically involves coating a high-temperature resistant acrylic resin adhesive with a thickness of 0.02 mm onto the circuit diagram. The temperature gradient is from low to high: 70℃--110℃---120℃--110℃. When the initial tack viscosity of the high-temperature resistant acrylic resin adhesive is above 1.2 N / mm, a PVC release film is used to cover the surface of the high-temperature resistant acrylic resin adhesive.

[0022] The specific steps for coating the foamed flame-retardant and high-temperature resistant rubber 4 in step 4) are as follows: A mixture of silicone rubber and nitrile rubber with a mass ratio of silicone rubber to nitrile rubber of 2:3 is prepared. Then, 0.8-1% of the mixture's mass of vulcanizing agent DCP, 1-2% of reinforcing agent fumed silica, 15-20% of flame retardant aluminum hydroxide, and 2-5% of foaming agent AC are added and mixed. The mixture is then soaked in ethyl acetate for 4-5 hours. After stirring evenly with a stirrer, the foamed flame-retardant and high-temperature resistant rubber 4 is obtained. The foamed flame-retardant and high-temperature resistant rubber 4 is then coated onto a coating machine according to the required thickness. The temperature gradient is from low to high: 90℃--110℃---130℃--150℃--130℃. The machine speed is determined based on the foaming effect. The thickness of the foamed flame-retardant and high-temperature resistant rubber 4 is not less than 0.15mm.

[0023] The beneficial effects of this invention are as follows:

[0024] The present invention uses nickel-chromium alloy foil 1 as a heat source, and a second insulating and thermally conductive adhesive layer 5 is attached to the inner side of the heat source. By utilizing its insulating and thermally conductive properties, the heat energy generated in the heat source is quickly conducted to the surface of the pipe, which greatly improves the efficiency of electrical energy to heat energy conversion.

[0025] The present invention coats a second insulating and thermally conductive adhesive layer 5 onto the circuit diagram of the nickel-chromium alloy foil 1, which facilitates construction and can be directly wrapped around the outer wall of the pipe; at the same time, it improves the tightness of the interface with the pipe, reduces air gaps, reduces the obstruction of heat conduction, and improves the conduction efficiency.

[0026] This invention coats a layer of foamed, flame-retardant, and high-temperature resistant rubber 4 onto fiberglass cloth. This rubber is not only an electrical insulator but also contains a large amount of still air. Still air is the best heat insulation medium, thus providing insulation and heat insulation, greatly reducing heat loss to the outside, and achieving a heat preservation effect, thereby achieving energy saving.

[0027] This invention provides an integrated composite tape for pipeline heating and insulation, which is simple in structure, easy to use, and safe and reliable. Attached Figure Description

[0028] Figure 1 This is a cross-sectional view of the composite heating and insulation strip for pipelines according to the present invention. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] Example 1, referring to Figure 1A composite tape for pipeline heating and insulation includes a 0.08mm thick nickel-chromium alloy foil 1, and outer surfaces of the nickel-chromium alloy foil 1 and inner surfaces of the fiberglass cloth 3, each coated with a 0.15mm thick third and fourth insulating thermally conductive adhesive layers. The third insulating thermally conductive adhesive layer on the outer surface of the nickel-chromium alloy foil 1 and the fourth insulating thermally conductive adhesive layer on the inner surface of the fiberglass cloth 3 are rolled and bonded together to form a 0.30mm thick first insulating thermally conductive adhesive layer 2. The outer surface of the first insulating thermally conductive adhesive layer 2 is provided with fiberglass cloth 3, and the outer surface of the fiberglass cloth 3 is provided with foamed flame-retardant and high-temperature resistant rubber 4. The inner surface of the nickel-chromium alloy foil 1 is provided with a second insulating thermally conductive adhesive layer 5.

[0031] Reference Figure 1 The preparation process of the composite tape for pipeline heating and insulation includes the following steps:

[0032] 1) On the outer side of nickel-chromium alloy foil 1 with different widths ranging from 20mm to 500mm and of varying lengths, and on the inner side of glass fiber cloth 3, a third insulating thermally conductive adhesive layer and a fourth insulating thermally conductive adhesive layer of the same thickness of 0.15mm are coated. The third insulating thermally conductive adhesive layer and the fourth insulating thermally conductive adhesive layer are modified insulating thermally conductive adhesives formed by mixing modified acrylic resin and modified thermally conductive filler powder, which are baked in a tunnel furnace to achieve gelation.

[0033] The modified thermally conductive filler powder is prepared as follows: silicon micro powder and alumina powder are prepared according to the mass ratio of silicon micro powder: alumina powder = 4:6. After the silicon micro powder and alumina powder are mixed evenly, KH-550 coupling agent accounting for 4% of the total mass of the mixture is added. The mixture is reacted at 110°C in a high-speed dispersion tank. After the reaction is complete in 3 hours, the temperature is lowered. When the temperature drops to 50°C, it is ready for use.

[0034] The modified acrylic resin is prepared by adding 12% (by mass) of bisphenol A type resin E-51 to acrylic acid T807, followed by 0.01-0.02% (by mass) of 2-methylimidazole to acrylic acid T807. The mixture is stirred uniformly at 90°C for 2-2.5 hours. When the viscosity of the reactants changes significantly (test method: when picking up the reactants with a glass rod, the reactants go from dripping downwards to forming a completely string-like consistency), the reaction is stopped, and the mixture is cooled to room temperature before being discharged for use.

[0035] Modified insulating and thermally conductive adhesive: Based on modified acrylic resin, 70% of its mass of modified thermally conductive filler powder is added. The modified thermally conductive filler and modified acrylic resin are mixed and stirred at high speed for 4-5 hours in a high-speed emulsifier. After cooling to room temperature by circulating water outside the emulsification tank, it is used.

[0036] The modified insulating and thermally conductive adhesive was coated onto nickel-chromium alloy foil 1 and glass fiber cloth 3 with a set thickness by roller coating and continuous baking. The temperature gradient was set from low, high, and medium: 90℃--110℃---130℃--160℃--140℃. The speed was determined according to the gelation time. After coating, the adhesive was baked in an oven to a pre-cured gel state.

[0037] 2) The third insulating thermally conductive adhesive layer on the outer side of the nickel-chromium alloy foil 1 and the fourth insulating thermally conductive adhesive layer on the inner side of the fiberglass cloth 3 are subjected to a temperature of 160℃ and a pressure of 2 kg / cm². 2 The lower roller presses and bonds the adhesive to form a first insulating and thermally conductive adhesive layer 2 with a thickness of 0.3 mm;

[0038] 3) The circuit diagram is screen-printed on the inner side of the nickel-chromium alloy foil 1 to achieve the set resistance value; then it is developed, chemically etched, cleaned, dried and inspected, and is ready for use after passing the inspection.

[0039] 4) A second insulating and thermally conductive adhesive layer 5 is coated on the nickel-chromium alloy foil 1 circuit diagram. The purpose is to facilitate construction, which can be directly wrapped around the outer wall of the pipe. At the same time, it improves the tightness between the interface with the pipe, reduces air gaps, and also helps to improve the heat transfer efficiency of the material. A layer of foamed flame-retardant and high-temperature resistant rubber 4 is coated on the outer side of the glass fiber cloth 3. It plays the role of insulation and heat insulation, and can keep a certain amount of heat from radiating outward, thereby achieving the role of energy saving and environmental protection.

[0040] In this embodiment, the coating of the second insulating and thermally conductive adhesive layer 5 specifically involves coating a high-temperature resistant acrylic resin adhesive with a thickness of 0.02 mm onto the circuit diagram. The temperature gradient is from low to high: 70℃--110℃---120℃--110℃. When the initial tack viscosity of the high-temperature resistant acrylic resin adhesive is above 1.2 N / mm, a PVC release film is used to cover the surface of the high-temperature resistant acrylic resin adhesive.

[0041] In this embodiment, the coating of foamed flame-retardant and high-temperature resistant rubber 4 is specifically carried out as follows: A mixture of silicone rubber and nitrile rubber with a mass ratio of silicone rubber to nitrile rubber of 2:3 is mixed, and then 0.8-1% of vulcanizing agent DCP, 1-2% of reinforcing agent fumed silica, 15-20% of flame retardant aluminum hydroxide, and 2-5% of foaming agent AC are added to the mixture. The mixture is then soaked in ethyl acetate for 4-5 hours, and stirred evenly with a stirrer to obtain foamed flame-retardant and high-temperature resistant rubber 4. The foamed flame-retardant and high-temperature resistant rubber 4 is then coated on a coating machine according to the required thickness, with the temperature gradient from low to high: 90℃--110℃---130℃--150℃--130℃. The machine speed is determined according to the foaming effect. The thickness of the foamed flame-retardant and high-temperature resistant rubber 4 is not less than 0.15mm to ensure the necessary heat insulation effect.

[0042] The beneficial effects of this embodiment are:

[0043] 1) The performance indicators of this embodiment are excellent, including thermal conductivity / W / mK greater than 1.5, thermal stress / 290℃ / min greater than 30 minutes without delamination or bubbling, and water absorption rate not higher than 2%.

[0044] 2) In this embodiment, nickel-chromium alloy foil 1 is used as a heat source. A second insulating and thermally conductive adhesive layer 5 is attached to the inner side of the heat source. By utilizing its insulating and thermally conductive properties, the heat energy generated in the heat source is quickly conducted to the surface of the pipe, which greatly improves the efficiency of electrical energy to heat energy conversion.

[0045] 3) In this embodiment, a second insulating and thermally conductive adhesive layer 5 is coated on the nickel-chromium alloy foil 1 circuit diagram, which facilitates construction and can be directly wrapped around the outer wall of the pipe; at the same time, it improves the tightness of the interface with the pipe, reduces air gaps, reduces the obstruction of heat conduction, and improves the conduction efficiency.

[0046] 4) To reduce heat loss, existing electric heating tapes on the market require an insulation layer to be added to the outside of the heating tape during use. In this embodiment, a layer of foamed flame-retardant and high-temperature resistant rubber 4 is coated on the fiberglass cloth. It is not only an electrical insulator, but also contains a large amount of still air. Still air is the best heat insulation medium, which plays a role in insulation and heat insulation, greatly reducing the heat loss to the outside, thus achieving the heat preservation effect and energy saving.

[0047] 5) For existing electric heating tapes on the market, it is generally recommended to use metal sheets to separate the overlapping parts to assist in heat dissipation. Otherwise, it will cause overheating at the overlapping parts, leading to premature damage. This embodiment has good thermal conductivity, is not easily damaged, and is easy to install.

[0048] 6) This embodiment is an integrated composite tape for pipeline heating and insulation, which has a simple structure, is easy to use, has a long service life, and is safe and reliable.

[0049] Example 2 differs from Example 1 in that the thickness of the nickel-chromium alloy foil 1 is changed to 0.05 mm, and the thickness of the first insulating thermally conductive adhesive layer 2 is changed to 0.2 mm; in the preparation process step 1), the mass ratio of modified thermally conductive filler powder in the modified insulating thermally conductive adhesive is changed to 65%, and the mass ratio of KH-550 coupling agent in the total mixture is changed to 3%; in step 2), the bonding temperature is changed to 150℃; other aspects are the same as in Example 1. The beneficial effects of this example are similar to those of Example 1.

[0050] Example 3 differs from Example 1 in that the thickness of the nickel-chromium alloy foil 1 is changed to 0.1 mm, and the thickness of the first insulating thermally conductive adhesive layer 2 is changed to 0.25 mm; in the preparation process step 1), the mass ratio of modified thermally conductive filler powder in the modified insulating thermally conductive adhesive is changed to 68%, and the mass ratio of KH-550 coupling agent in the total mixture is changed to 5%; in step 2), the bonding temperature is changed to 170℃; other aspects are the same as in Example 1. The beneficial effects of this example are similar to those of Example 1.

Claims

1. A manufacturing process for a composite heating and insulation strip for pipelines, characterized in that, A composite tape for pipe heating and insulation includes a nickel-chromium alloy foil (1), a first insulating and thermally conductive adhesive layer (2) on the outer side of the nickel-chromium alloy foil (1), a glass fiber cloth (3) on the outer side of the first insulating and thermally conductive adhesive layer (2), and a foamed flame-retardant and high-temperature resistant rubber (4) on the outer side of the glass fiber cloth (3); and a second insulating and thermally conductive adhesive layer (5) on the inner side of the nickel-chromium alloy foil (1). The preparation process of the composite tape for pipeline heating and insulation includes the following steps: 1) A third insulating thermal conductive adhesive layer and a fourth insulating thermal conductive adhesive layer are coated on the outer side of the nickel-chromium alloy foil (1) and the inner side of the glass fiber cloth (3). The third insulating thermal conductive adhesive layer and the fourth insulating thermal conductive adhesive layer are modified insulating thermal conductive adhesives formed by mixing modified acrylic resin and modified thermal conductive filler powder, which are baked in the tunnel furnace to reach the gel state. The modified thermally conductive filler powder in step 1) is prepared as follows: silicon micro powder and alumina powder are prepared according to the mass ratio of silicon micro powder: alumina powder = 4:

6. After the silicon micro powder and alumina powder are mixed evenly, KH-550 coupling agent accounting for 3-5% of the total mass of the mixture is added. The mixture is reacted at 110°C in a high-speed dispersion tank. After the reaction is complete in 3 hours, the temperature is lowered. When the temperature drops to 50°C, it is ready for use. The modified acrylic resin is prepared by adding 12% (by mass) of bisphenol A type resin E-51 to acrylic acid T807, and then using 0.01-0.02% (by mass) of 2-methylimidazole as an initiator. The mixture is stirred uniformly at 90°C for 2-2.5 hours. When the viscosity of the reactants changes significantly, i.e. when the reactants are picked up with a glass rod, the reactants go from dripping downwards to forming a completely string-like shape. At this point, the reaction is stopped, the mixture is cooled to room temperature by passing water through it, and then it is discharged for use. Modified insulating and thermally conductive adhesive: Based on modified acrylic resin, 65-70% of its mass of modified thermally conductive filler powder is added. The modified thermally conductive filler and modified acrylic resin are mixed and stirred at high speed for 4-5 hours in a high-speed emulsifier. After cooling to room temperature by circulating water outside the emulsification tank, it is used. The modified insulating and thermally conductive adhesive was coated onto nickel-chromium alloy foil (1) and glass fiber cloth (3) with a set thickness by roller coating and continuous baking. The temperature gradient was set from low, high and medium: 90℃--110℃---130℃--160℃--140℃. The speed was determined according to the gelation time. After coating, the adhesive was baked in an oven to a pre-cured gel state. 2) Roll-press the third insulating thermally conductive adhesive layer on the outer side of the nickel-chromium alloy foil (1) and the fourth insulating thermally conductive adhesive layer on the inner side of the glass fiber cloth (3) to form the first insulating thermally conductive adhesive layer (2); 3) Print the circuit diagram on the inner side of the nickel-chromium alloy foil (1) to make the nickel-chromium alloy foil (1) reach the set resistance value; after etching, clean it with water and dry it. 4) A second insulating and thermally conductive adhesive layer (5) is coated on the circuit diagram of the nickel-chromium alloy foil (1), and a layer of foamed flame-retardant and high-temperature resistant rubber (4) is coated on the outer side of the glass fiber cloth (3); The process of coating the foamed flame-retardant and high-temperature resistant rubber (4) in step 4) is as follows: a mixture of silicone rubber and nitrile rubber with a mass ratio of silicone rubber:nitrile rubber = 2:3 is prepared, and then 0.8-1% of vulcanizing agent DCP, 1-2% of reinforcing agent fumed silica, 15-20% of flame retardant aluminum hydroxide, and 2-5% of foaming agent AC are added to the mixture. The mixture is then soaked in ethyl acetate. After 4-5 hours, it is stirred evenly with a stirrer to obtain the foamed flame-retardant and high-temperature resistant rubber (4). The foamed flame-retardant and high-temperature resistant rubber (4) is coated on a coating machine according to the required thickness. The temperature gradient is from low to high: 90℃--110℃---130℃--150℃--130℃. The speed is determined according to the foaming effect. The thickness of the foamed flame-retardant and high-temperature resistant rubber (4) is not less than 150um.

2. The process according to claim 1, characterized in that: The nickel-chromium alloy foil (1) has a thickness of 0.05-0.1 mm.

3. The process according to claim 1, characterized in that: A composite tape for pipe heating and insulation comes in different widths from 20mm to 100mm.

4. The process according to claim 1, characterized in that: In step 1), the thickness of the third and fourth insulating thermally conductive adhesive layers is 0.10-0.15 mm.

5. The process according to claim 1, characterized in that: Step 2) Roller bonding is performed at a temperature of 150-170℃ and a pressure of 2 kg / cm². 2 The following will proceed.

6. The process according to claim 1, characterized in that: The second insulating and thermally conductive adhesive layer (5) in step 4) is specifically applied by coating a 20µm thick high-temperature resistant acrylic resin adhesive on the circuit diagram. The temperature gradient is from low to high: 70℃--110℃---120℃--110℃. When the initial tack viscosity of the high-temperature resistant acrylic resin adhesive is above 1.2N / mm, a PVC release film is used to cover the surface of the high-temperature resistant acrylic resin adhesive.

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