Flexible railway through ground wire

Abstract

The invention discloses a flexible railway through ground wire which is formed by twisting a plurality of flexible wire bodies, each flexible wire body comprises a guide core and a composite graphene coating located on the surface of the guide core, and the composite graphene coating is formed by coating and curing composite graphene liquid. The composite graphene liquid comprises the following components in parts by weight: 30-65 parts of a film-forming resin base material, 3-10 parts of graphene, 0.8-3.5 parts of a dispersing agent, 0.3-2.5 parts of a rheology modifier and 1-2 parts of an adhesion promoter, and the composite graphene liquid is very convenient to install and lay and is not easy to steal.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, especially to the technical field of railway continuous ground wires. Background Art

[0002] The railway comprehensive grounding system uses the railway continuous ground wire laid on both sides of the railway as the grounding main line, and connects electrical and electronic system equipment of various specialties along the railway, the internal structural steel bars of buildings, long metal parts, etc. into an integrated common grounding system in an equipotential connection manner; as the main artery of the railway comprehensive grounding system, the railway continuous ground wire plays an important role in connecting each system and discharging current to the ground, and can provide a stable zero-potential grounding point for each signal system; the railway continuous ground wire has the outstanding characteristics of realizing equipotential of trackside equipment and reducing the grounding resistance, and is also a redundant channel for traction return current of electrified railways.

[0003] Most of the existing railway continuous ground wires are copper alloy sheath continuous ground wires (the outer sheath is usually hard and golden yellow in color), such as a railway continuous ground wire with the publication number of CN106981327A; in the actual application process, due to the hard texture (not easy to bend) of the copper alloy sheath, workers often cannot place the copper alloy sheath continuous ground wire flatly in the cable trough when laying the continuous ground wire across the bridge tunnel (bending and exposure will not only cause greater discharge risks, but also greatly increase the difficulty of on-site construction); in addition, because this kind of outer sheath has a high economic value and is very easy to be disassembled, it is seriously stolen on site (this greatly increases the safety hazards of the railway signal system). Summary of the Invention

[0004] The purpose of the present invention is to solve the problems in the prior art, and propose a flexible railway continuous ground wire, which is very convenient for laying and not easy to be stolen.

[0005] To achieve the above purpose, the present invention proposes a flexible railway continuous ground wire, which is formed by stranding a plurality of flexible wire bodies. The flexible wire body includes a core and a composite graphene coating on the surface of the core. The composite graphene coating is formed by coating and curing with composite graphene liquid. The composite graphene liquid includes 30 - 65 parts by weight of a film-forming resin substrate, 3 - 10 parts of graphene, 0.8 - 3.5 parts of a dispersant, 0.3 - 2.5 parts of a rheology regulator, and 1 - 2 parts of an adhesion promoter.

[0006] Preferably, the resistivity of the composite graphene coating is not greater than 0.018Ω·mm 2 / m.

[0007] Preferably, the film-forming resin substrate is a mixed resin of acrylic resin and polyurethane resin, and the mixing ratio of the acrylic resin to the polyurethane resin is controlled at 1 - 4:1.

[0008] Preferably, the dispersant is a polycarboxylate-based polymer dispersant or a modified silane dispersant.

[0009] Preferably, the rheology modifier is a combined agent of a thickener and a wetting agent, and the combination ratio of the thickener to the wetting agent is controlled at 1:0.5 - 2.

[0010] Preferably, the thickener is one or a combination of several of hydroxyethyl cellulose, hydrophobically modified polyurethane, and fumed silica.

[0011] Preferably, the wetting agent is selected from silicone oxygen alkane wetting agents or fluorocarbon wetting agents.

[0012] Preferably, the adhesion promoter is a silane coupling agent.

[0013] Preferably, the composite graphene liquid is sprayed on the outside of the conducting core at least three times to cure and form a composite graphene coating with a thickness of 0.03 - 0.08 mm.

[0014] Preferably, the curing is carried out in two stages. The first stage is to dry at 80 - 100 °C for 2 - 5 min, and the second stage is to dry at 120 - 150 °C for 3 - 8 min.

[0015] Advantages of the present invention: 1) By coating the composite graphene liquid on the surface of the conductor and curing to form a composite graphene coating, a flexible wire body with super conductivity and good heat conductivity can be obtained. Thus, when several flexible wire bodies are twisted to form a flexible railway through ground wire, the traditional hard copper alloy sheath can be omitted. It can not only connect the traction power supply return, power supply, signal, communication, and other electronic information systems and various devices along the railway in the railway signal system and form an equipotential connection, realizing functions such as anti-electromagnetic induction interference, anti-static interference, and anti-lightning intrusion of the equipment along the railway, but also be very convenient for installation and laying, and is not easily stolen (the theft value of the composite graphene coating is relatively low compared to that of the copper alloy sheath); 2) When the thickness of the composite graphene coating is 0.03 - 0.08 mm, it is black and transparent (single-layer graphene is nearly transparent; for multi-layer graphene, the light transmittance gradually decreases with the increase in the number of layers and shows dark gray to black); among them, the better light transmittance on the one hand makes defects such as uneven coating thickness, internal air bubbles, and cracks visible under backlight (convenient for quality inspection), and on the other hand allows the infrared instrument to quickly scan the temperature distribution of the whole line to quickly locate the poor contact points (supporting non-destructive testing), while the black appearance enables the flexible railway through ground wire to blend into the dim environment to further reduce the theft probability (reducing visibility and decreasing the attractiveness of theft); 3) The composite graphene coating also has advantages such as good solubility (when repairing circuits, the composite graphene coating can be removed by locally spraying solvent for dissolution during circuit maintenance without cutting the outer shell; retired ground wires can also be batch-soaked in solvent to separate the conducting cores for resource recycling), permeability, and corrosion resistance (resisting harsh environments such as humidity and saline-alkali land). 4) By adding specific proportions of film-forming resin substrates, dispersants, rheology regulators, and adhesion promoters to the formulation, the composite graphene coating can not only adapt to the bending or dynamic environment of the ground wire but also spread evenly and firmly outside the conducting core.

[0016] The features and advantages of the present invention will be described in detail through examples in conjunction with the accompanying drawings. Description of the Drawings

[0017] Figure 1 is the front view of the flexible railway through ground wire of the present invention; In the figure: 1 - conducting core, 2 - composite graphene coating. Detailed Embodiments

[0018] Embodiment 1: Refer to Figure 1 , the flexible railway through ground wire of the present invention is formed by stranding 19 flexible wire bodies. The flexible wire bodies include a conducting core 1 and a composite graphene coating 2 on the surface of the conducting core 1. The composite graphene coating 2 is formed by coating and curing composite graphene liquid. The composite graphene liquid includes 45 parts by weight of a film-forming resin substrate, 6.5 parts of graphene, 2 parts of a dispersant, 1.5 parts of a rheology regulator, and 1.5 parts of an adhesion promoter.

[0019] The conducting core 1 is a copper wire.

[0020] The film-forming resin substrate is a mixed resin of acrylic resin and polyurethane resin, and the mixing ratio of the acrylic resin to the polyurethane resin is controlled at 2:1. In the formulation, on the one hand, the film-forming resin substrate serves as the main component of the composite graphene coating 2, forming a continuous film to wrap graphene and other additives, providing the mechanical strength, adhesion, and weather resistance of the composite graphene coating 2. On the other hand, it can also play a role in dispersing and stabilizing graphene (through its own rheological properties, such as viscosity and wettability, thus assisting the dispersant to achieve uniform distribution of graphene in the liquid phase and preventing agglomeration) and an interfacial bonding bridge (which can cooperate with the adhesion promoter to effectively enhance the interfacial bonding force between the composite graphene coating 2 and the guiding core 1). Among them, the acrylic resin can endow the composite graphene coating 2 with high hardness, UV resistance, and chemical resistance (the acrylic resin can provide the film-forming main chain, but too high a content is likely to affect the flexibility of the composite graphene coating 2), and is suitable for rapid curing (matching the curing temperature of 120 - 150 °C), while the polyurethane resin can enhance the flexibility, abrasion resistance, and impact resistance of the composite graphene coating 2, balancing the rigidity of the acrylic resin (the polyurethane resin is used to adjust the toughness and can be complementary to the acrylic resin), and adapting to the bending or dynamic environment of the ground wire.

[0021] The dispersant is a polycarboxylate-based polymer dispersant (Tego Dispers 755), which can provide a dual stabilizing mechanism of steric hindrance and electrostatics for the high specific surface area characteristics of graphene, thus ensuring the uniform dispersion of graphene.

[0022] The rheology regulator is a combined agent of a thickener and a wetting agent. The combination ratio of the thickener to the wetting agent is controlled at 1:1. The thickener is hydroxyethyl cellulose, and the wetting agent is selected as an organosiloxane wetting agent (BYK-345). In the formulation, the addition of the rheology regulator can improve the surface smoothness (using the wetting agent to reduce orange peel or fisheye phenomena caused by uneven substrate wetting), strengthen the adhesion (on the one hand, using the wetting agent to promote the contact between the composite graphene liquid and the substrate, and on the other hand, using the thickener to make the adhesion promoter more evenly distributed at the interface by regulating the viscosity to enhance the bonding strength), and enhance the integrity of the conductive network (using the wetting agent to assist the directional arrangement of graphene on the substrate surface, and also using the thickener to slow down the sedimentation rate of graphene through viscosity control, thereby ensuring the continuity of the conductive network after curing through the cooperation of the two and avoiding local resistivity fluctuations).

[0023] The adhesion promoter is a silane coupling agent (vinyltriethoxysilane).

[0024] The composite graphene liquid is sprayed onto the outside of the guide core 1 in three times to cure and form a composite graphene coating 2 with a thickness of 0.05 mm. The curing is carried out in two stages. The first stage is to dry at 90 °C for 3 min, and the second stage is to dry at 135 °C for 5 min. Among them, the guide core 1 needs to be first drawn into a single wire diameter with the required specifications by a large drawing machine with a fixed mold, and then subjected to a cleaning treatment. In addition, this method of spraying in batches and drying step by step in stages can further ensure that the composite graphene coating 2 adheres tightly to the surface of the guide core 1 and has a uniform thickness.

[0025] Examples 2 to 5: In the formula, the thickener is mainly used to increase the viscosity of the composite graphene liquid and prevent it from sagging during spraying (especially during construction on vertical surfaces). However, adding too much will cause difficulties in spraying atomization and too thick a coating. The wetting agent is mainly used to reduce the surface tension of the composite graphene liquid and improve its spreading property on the guide core 1. However, adding too much may cause bubbles or surface unevenness. In addition, the compounding of the thickener and the wetting agent can also prevent phase separation and sedimentation (the thickener can inhibit the sedimentation of graphene by increasing the system viscosity, while the wetting agent can promote the coating of the dispersant on graphene by reducing the interfacial energy. When the ratio of the two is within a suitable range, the long-term stability of the dispersion system can be maintained). Based on this, in Examples 2 to 5, the combined ratio of the thickener and the wetting agent is adjusted, and the others are the same as in Example 1.

[0026]

[0027] Table 1 Coating comparison of Examples 1 to 5

[0028] The specific ratios of the thickener and the wetting agent, the spraying effect, and the adhesion of Examples 1 to 5 are specifically shown in Table 1 above. Among them, Example 1 shows the best spraying effect and adhesion. Excessive wetting agent easily causes the solvent evaporation path to be blocked during curing and forms pinholes, while excessive thickener may cause the coating to shrink and crack due to a sudden change in viscosity.

[0029] In addition, the ratio of the thickener and the wetting agent can also be selected according to the spraying process. Specifically, a low ratio (1:0.5) is suitable for high-pressure airless spraying (high-viscosity liquids can reduce atomization and scattering), while a high ratio (1:2) is suitable for air spraying or dip coating (low-viscosity liquids are more likely to form a uniform film).

[0030] The above examples are illustrative of the present invention, not limiting of the present invention. Any simply transformed scheme of the present invention belongs to the protection scope of the present invention.

Claims

1. Flexible railway continuous ground wire, characterized in that: It is formed by twisting a number of flexible wire bodies. The flexible wire body includes a conducting core (1) and a composite graphene coating (2) located on the surface of the conducting core (1). The composite graphene coating (2) is formed by spraying and curing a composite graphene liquid. The composite graphene liquid includes 30 - 65 parts by weight of a film-forming resin substrate, 3 - 10 parts of graphene, 0.8 - 3.5 parts of a dispersant, 0.3 - 2.5 parts of a rheology modifier, and 1 - 2 parts of an adhesion promoter.

2. The flexible railway continuous ground wire according to claim 1, characterized in that: The resistivity of the composite graphene coating (2) is not greater than 0.018 Ω·mm 2 / m.

3. The flexible railway continuous ground wire according to claim 1, characterized in that: The film-forming resin substrate is a mixed resin of acrylic resin and polyurethane resin, and the mixing ratio of the acrylic resin to the polyurethane resin is controlled at 1 - 4:

1.

4. The flexible railway continuous ground wire according to claim 1, wherein: The dispersant is a polycarboxylate-based polymer dispersant or a modified silane dispersant.

5. The flexible railway continuous ground wire according to claim 1, wherein: The rheology modifier is a combined agent of a thickener and a wetting agent, and the combined ratio of the thickener to the wetting agent is controlled at 1:0.5 - 2.

6. The flexible railway continuous ground wire according to claim 5, wherein: The thickener is one or a combination of several of hydroxyethyl cellulose, hydrophobically modified polyurethane, and fumed silica.

7. The flexible railway continuous ground wire according to claim 5, characterized in that: The wetting agent is selected from silicone oxygen alkane wetting agents or fluorocarbon wetting agents.

8. The flexible railway through line as claimed in claim 1, wherein: The adhesion promoter is a silane coupling agent.

9. The flexible railway continuous ground wire according to claim 1, characterized in that: The composite graphene liquid is sprayed on the outside of the conducting core (1) at least three times to cure and form a composite graphene coating (2) with a thickness of 0.03 - 0.08 mm.

10. The flexible railway continuous ground wire according to claim 9, characterized in that: The curing is carried out in two stages. The first stage is to dry at 80 - 100 °C for 2 - 5 min, and the second stage is to dry at 120 - 150 °C for 3 - 8 min.

Images