Semi-conductive coating material for regulating and controlling non-linear effect of insulation resistance and preparation method of semi-conductive coating material

Abstract

The invention provides a semiconductive coating material for regulating and controlling an insulation resistance nonlinear effect and a preparation method thereof. The semiconductive coating material comprises high-activity epoxy resin, high-performance epoxy resin, a normal-temperature curing agent, a conductive filler and a semiconductor filler, wherein the mass ratio of the high-activity epoxy resin to the high-performance epoxy resin is 1: (0.5-3), the addition amount of the normal-temperature curing agent is 10-30% of the total mass of the resin mixture, and the addition amount of the conductive filler is 0.1-10% of the total mass of the resin mixture; the addition amount of the semiconductor filler is 10%-20% of the total mass of the resin mixture. According to the invention, the high-performance and high-activity epoxy resin is firstly mixed as a matrix, and then the normal-temperature curing agent is added for mixing, so that bubbles generated in the stirring process can be eliminated, and the conductive filler and the semiconductor filler are promoted to be uniformly dispersed in the resin matrix and play a synergistic role, thereby realizing effective regulation and control on the non-linear effect of the insulation resistance; the process is simple and easy for industrial implementation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power equipment insulation materials, in particular to a semi-conductive coating material for regulating the nonlinear effect of insulation resistance and a preparation method thereof. BACKGROUND

[0002] The outer insulation sleeve of the ±1100kV voltage ratio standard device adopts epoxy composite material. With the increase of voltage grade, a large amount of electric charge accumulates at the interface of the insulation material, resulting in extremely uneven electric field distribution. Under the action of such high field strength, the sleeve material exhibits a significant nonlinear effect of resistance, that is, its volume resistivity decreases sharply with the increase of electric field strength, thereby affecting the stability of the internal potential distribution of the device, and ultimately seriously reducing the measurement accuracy of the standard device, which needs to be treated.

[0003] The core of treating the nonlinear effect of insulation resistance is to improve the uneven electric field caused by the nonlinear effect of resistance. Traditional methods include measures such as arranging voltage grading rings, parallel voltage grading capacitors or optimizing electrode shapes, but such methods are limited by the structure of the device.

[0004] In recent years, coating a semi-conductive coating on the surface of the insulation medium can also effectively improve the uneven electric field distribution, and is not limited by the structure, which is economical and practical. However, the existing semi-conductive coating material relies on high-temperature curing process, but the size of the outer insulation sleeve of the voltage ratio standard device is large, and after coating the semi-conductive coating, it cannot be placed in the high-temperature curing box, and can only be cured at room temperature. At present, there is still a lack of a semi-conductive coating material that has the functions of room temperature rapid curing and effectively regulating the nonlinear effect of insulation resistance. Therefore, it is urgent to develop a semi-conductive coating material suitable for large high-voltage standard device insulation sleeves, which can be rapidly cured at room temperature, can effectively regulate the nonlinear effect of insulation resistance, and can improve the electric field distribution. SUMMARY

[0005] In view of this, the present application provides a semi-conductive coating material for regulating the nonlinear effect of insulation resistance and a preparation method thereof, aiming to solve the problems that the existing semi-conductive coating relies on high-temperature curing and is difficult to be applied to large-size insulation sleeves, and cannot effectively regulate the nonlinear effect of insulation resistance at room temperature. In one aspect, the present application provides a semi-conductive coating material for regulating the nonlinear effect of insulation resistance, comprising: a high-activity epoxy resin, a high-performance epoxy resin, a room temperature curing agent, a conductive filler, a semiconductor filler, a defoaming agent and a leveling agent, wherein the mass ratio of the high-activity epoxy resin to the high-performance epoxy resin is 1: (0.5-3), the epoxy value of the high-activity epoxy resin is 0.5-0.6, and the epoxy value of the high-performance epoxy resin is 0.2-0.4; the addition amount of the room temperature curing agent is 10-30% of the total mass of the resin mixture; the addition amount of the conductive filler is 0.1%-10% of the total mass of the resin mixture; the addition amount of the semiconductor filler is 10%-20% of the total mass of the resin mixture; and the total addition amount of the defoaming agent and the leveling agent is 1%-5% of the total mass of the resin mixture.

[0006] Further, in the semi-conductive coating material for regulating the nonlinear effect of insulation resistance, the high-activity epoxy resin is a bisphenol F type epoxy resin or a phenolic type epoxy resin.

[0007] Further, in the semi-conductive coating material for regulating the nonlinear effect of insulation resistance, the high-performance epoxy resin is a bisphenol A type epoxy resin or an organic silicon modified epoxy resin.

[0008] Further, in the semi-conductive coating material for regulating the nonlinear effect of insulation resistance, the room temperature curing agent is selected from at least one of triethylene tetramine, polyether amine, ethylenediamine and diethylene triamine.

[0009] Further, in the semi-conductive coating material for regulating the nonlinear effect of insulation resistance, when the room temperature curing agent is triethylene tetramine, ethylenediamine or diethylene triamine, the addition amount is 10%-15% of the total mass of the resin mixture.

[0010] Further, in the semi-conductive coating material for regulating the nonlinear effect of insulation resistance, when the room temperature curing agent is polyether amine, the addition amount is 25%-30% of the total mass of the resin mixture, and further, a curing accelerator accounting for 2%-3% of the total mass of the resin mixture is added.

[0011] The semi-conductive coating material for regulating the nonlinear effect of insulation resistance in the application adopts a mixed matrix composed of high-activity epoxy resin and high-performance epoxy resin, both of which have good structural compatibility. Under the action of a normal-temperature curing agent, the two types of epoxy groups undergo a synergistic reaction to form an interpenetrating mixed crosslinking network. This network structure not only enables the coating to be rapidly cured at normal temperature without the need for high-temperature post-processing, which is suitable for on-site construction of high-voltage grade large-size insulation sleeves, but also guarantees the curing reaction rate due to the high-activity epoxy resin and improves the adhesion and anti-cracking ability of the coating due to the high molecular weight and flexible chain segments of the high-performance epoxy resin, thereby achieving a balance between processability and mechanical properties. Especially, the addition of conductive fillers and semiconductor fillers in the resin matrix provides an initial conductive path and reduces the overall resistance of the system, and the semiconductor fillers are activated under a high electric field to disperse the current in the conductive network formed by the conductive fillers, thereby effectively regulating the nonlinear response characteristics of the insulation resistance.

[0012] In another aspect, the application also provides a preparation method of the semi-conductive coating material for regulating the nonlinear effect of insulation resistance, characterized by comprising the following steps: mixing high-activity epoxy resin and high-performance epoxy resin in a mass ratio of 1: (0.5-3) to obtain a mixed resin matrix; wherein the epoxy value of the high-activity epoxy resin is 0.5-0.6, and the epoxy value of the high-performance epoxy resin is 0.2-0.4; adding a defoaming agent and a leveling agent to the mixed resin matrix, stirring at a preset speed at normal temperature until a uniform liquid phase is formed; wherein the total amount of the defoaming agent and the leveling agent added is 1%-5% of the total mass of the resin mixture; adding conductive fillers and semiconductor fillers to the uniform liquid phase and continuing to stir until the fillers are uniformly dispersed; wherein the addition amount of the conductive fillers is 0.1%-10% of the total mass of the resin mixture, and the addition amount of the semiconductor fillers is 10%-20% of the total mass of the resin mixture; adding a normal-temperature curing agent to the above mixture, wherein the addition amount of the normal-temperature curing agent is 10%-30% of the total mass of the resin mixture, and continuing to stir to obtain a semi-conductive coating premix liquid; coating the semi-conductive coating premix liquid on the surface of a substrate and curing at normal temperature to obtain the semi-conductive coating material for regulating the nonlinear effect of insulation resistance.

[0013] Further, in the above preparation method, the conductive fillers are at least one of carbon black, carbon nanotubes and graphene.

[0014] Further, in the above preparation method, the semiconductor fillers are at least one of silicon carbide, titanium dioxide and zinc oxide.

[0015] Furthermore, in the above preparation method, the amount of defoamer added is 0.5% of the total mass of the resin mixture; the amount of leveling agent added is 2% of the total mass of the resin mixture.

[0016] The present invention provides a method for preparing a semiconductive coating material for controlling the nonlinear effect of insulation resistance. First, a high-performance and highly active epoxy resin is mixed as a matrix. Then, defoamers, leveling agents, and other additives are added to the matrix and stirred to disperse them. Next, conductive and semiconductive fillers are added and dispersed further. Finally, a room-temperature curing agent is added and mixed. This order of addition helps eliminate air bubbles generated during stirring and prevents the mixture from curing prematurely due to the addition of the curing agent, which could lead to coating failure. Simultaneously, it promotes the uniform dispersion and synergistic effect of conductive and semiconductive fillers in the resin matrix, thereby effectively controlling the nonlinear effect of insulation resistance. The process is simple and easy to implement industrially. Attached Figure Description

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figures 1-6 The images show physical photos of the adhesion test results of the semiconductive coating materials used to control the nonlinear effect of insulation resistance provided in Examples 1-4 of this invention and the semiconductive coating materials prepared in Comparative Examples 1-2; wherein: Figure 1 , Figure 2 , Figure 3 , Figure 4 The images shown are actual photos of the adhesion test results (adhesion level 0) for Embodiments 1-4 of the present invention. Figure 5 , Figure 6 The images below show the actual photos of the adhesion test results for Comparative Examples 1 and 2 (adhesion level 1). Figures 7-12 The images show physical photos of the flexibility test results of the semiconductive coating materials used to control the nonlinear effect of insulation resistance provided in Examples 1-4 of this invention and the semiconductive coating materials prepared in Comparative Examples 1-2; wherein: Figure 7 , Figure 8 , Figure 9 , Figure 10 The images show the actual results of the flexibility test in Examples 1-4 (the flexibility of all shafts numbered 1-7 is satisfied). Figure 11 The image shows the actual results of the flexibility test for Comparative Example 1 (the flexibility of the shaft bar numbered 6 is not met). Figure 12 The image shows the actual results of the flexibility test for Comparative Example 2 (the flexibility of the shaft bar numbered 7 is not met). Figure 13 The resistance value of the semiconductive coating material provided for regulating the nonlinear effect of insulation resistance of the inventive examples 1-4 and the semiconductive coating material prepared in the comparative examples 1-2 is plotted against the voltage change to characterize the nonlinear characteristics of the respective resistance. DETAILED DESCRIPTION

[0018] Exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it is understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure can be more thoroughly understood, and the scope of the present disclosure can be accurately conveyed to those skilled in the art. It should be noted that the embodiments in the present disclosure and the features in the embodiments can be combined with each other without conflict. The present disclosure will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0019] The first aspect of the present disclosure provides a semiconductive coating material for regulating the nonlinear effect of insulation resistance, comprising: a high-activity epoxy resin, a high-performance epoxy resin, a room temperature curing agent, a conductive filler, a semiconductor filler, a defoaming agent, and a leveling agent; wherein the mass ratio of the high-activity epoxy resin to the high-performance epoxy resin is 1:(0.5-3), the addition amount of the room temperature curing agent is 10-30% of the total mass of the resin mixture, the addition amount of the conductive filler is 0.1%-10% of the total mass of the resin mixture, the addition amount of the semiconductor filler is 10%-20% of the total mass of the resin mixture, and the total amount of the defoaming agent and the leveling agent added is 1%-5% of the total mass of the resin mixture.

[0020] Specifically, the high-activity epoxy resin is an epoxy resin with an epoxy value in the range of 0.5-0.6, preferably a bisphenol F type epoxy resin (such as a phenolic F51 resin with an epoxy ester of 0.51) or a phenolic type epoxy resin (such as a bisphenol F type epoxy resin 830 with an epoxy ester of 0.60).

[0021] The high-performance epoxy resin is an epoxy resin with an epoxy value in the range of 0.2-0.4, preferably a bisphenol A type epoxy resin (such as an E-42 type epoxy resin with an epoxy value of 0.4) or a silicone-modified epoxy resin (such as an S-16 silicone-modified epoxy resin with an epoxy ester of 0.20).

[0022] The room temperature curing agent is selected from at least one of triethylene tetramine, polyether amine, ethylenediamine, and diethylene triamine. When a high-activity hydrogen density aliphatic amine curing agent (such as triethylene tetramine, ethylenediamine, and diethylene triamine) is used, the addition amount can be as low as 10%-15%; for example, it can be 10%, 13%, 15%, 20%, 25%, or 30%.

[0023] When using polyetheramine curing agents, due to their large molecular weight and low reactivity, the addition amount is typically 25%–30%. It is preferable to add 2%–3% of a curing accelerator by mass of the total resin mixture to accelerate room temperature curing and increase crosslinking density. More specifically, 8030 accelerator can be added. 8030 accelerator is a commercially available modified amine curing accelerator used to promote the crosslinking reaction between polyetheramine and epoxy resin at room temperature.

[0024] In this embodiment, the defoamer and leveling agent can be selected from commercially available products commonly used in the art, depending on the specific circumstances. More specifically, the defoamer can be a polysiloxane defoamer (e.g., BYK-066N). The leveling agent can be a polyether-modified polydimethylsiloxane leveling agent (e.g., BYK-333). Adding the defoamer can eliminate... To eliminate air bubbles generated during the mixing of components and prevent pores after curing, a leveling agent is added to reduce the surface tension of the mixture, improving the spreadability and surface smoothness of the coating. It can be seen that the semi-conductive coating material of this invention uses a mixed matrix composed of highly reactive epoxy resin and high-performance epoxy resin. These two materials have good structural compatibility, and under the action of a room-temperature curing agent, the two types of epoxy groups undergo a synergistic reaction to form an interpenetrating mixed cross-linked network. This network structure not only allows the coating to cure rapidly at room temperature without high-temperature post-treatment, making it suitable for on-site construction of large-size insulating sleeves with high voltage levels, but also ensures a high curing reaction rate due to the high-activity epoxy resin, while the high-performance epoxy resin, due to its higher molecular weight and flexible segments, enhances the coating's adhesion and crack resistance. The two work synergistically to achieve a balance between processability and mechanical properties. In particular, the addition of conductive fillers and semiconductor fillers to the resin matrix provides an initial conductive path, reducing the overall resistance of the system; the semiconductor fillers are activated under a high electric field to disperse the current in the conductive network formed by the conductive fillers, thereby effectively controlling the nonlinear response characteristics of the insulation resistance.

[0025] A second aspect of the present invention provides a method for preparing a semiconductive coating material for controlling the nonlinear effect of insulation resistance, comprising the following steps: (1) A high-activity epoxy resin and a high-performance epoxy resin are mixed at a mass ratio of 1:(0.5-3) to obtain a mixed resin matrix; wherein the epoxy value of the high-activity epoxy resin is 0.5-0.6 and the epoxy value of the high-performance epoxy resin is 0.2-0.4. (2) Add defoamer and leveling agent to the mixed resin matrix and stir at a preset speed at room temperature until a homogeneous liquid phase is formed; wherein, the total amount of defoamer and leveling agent added is 1% to 5% of the total mass of the resin mixture; preferably, the amount of defoamer added is 0.5% of the total mass of the resin mixture; and the amount of leveling agent added is 2% of the total mass of the resin mixture.

[0026] (3) adding conductive fillers and semiconductor fillers into the uniform liquid phase and continuing to stir until the fillers are uniformly dispersed.

[0027] More specifically, the conductive fillers can be at least one of carbon black, carbon nanotubes and graphene.

[0028] Due to the significant differences in specific surface area, aspect ratio and conductive network formation ability of different conductive fillers, the addition amount needs to be adjusted accordingly. Generally, the total addition amount of conductive fillers is 0.1% to 10% of the total mass of the resin mixture. Among them, carbon black usually needs to be added by 3% to 8% due to its low conductivity efficiency; carbon nanotubes only need 0.1% to 0.5% due to its high aspect ratio and high conductivity; graphene is usually used 1% to 3%.

[0029] The semiconductor fillers can be at least one of silicon carbide, titanium dioxide and zinc oxide. The addition amount can be 10% to 20% of the mass of the resin mixture in order to form a semiconductor filler network that effectively regulates the electric field.

[0030] Preferably, carbon black is selected as the conductive filler and silicon carbide is selected as the semiconductor filler in this embodiment to synergistically regulate the nonlinear characteristics of the semiconductive coating. Carbon black provides an initial conductive path and reduces the overall resistance of the system; as the electric field increases and gradually exceeds the threshold field strength of carbon black, the current of the conductive network composed of carbon black will increase sharply. Under high electric field, silicon carbide is activated to form new conductive channels, dispersing the current of the carbon black conductive network and avoiding the phenomenon of sharp increase in current of the carbon black conductive network under strong electric field, i.e. effectively suppressing the sharp increase in current, which helps to regulate the nonlinear characteristics of the insulation resistance.

[0031] In this step, the stirring speed can be 400 to 500 r / min and the stirring time can be 30 to 90 min.

[0032] (4) adding a room temperature curing agent to the above mixture, the addition amount of the room temperature curing agent being 10% to 30% of the total mass of the resin mixture, and continuing to stir to obtain a semiconductive coating premix liquid.

[0033] More specifically, the stirring speed can be 400 to 500 r / min and the stirring time can be 30 to 90 min.

[0034] (5) coating the premix liquid on the surface of a substrate and curing at room temperature to obtain the semiconductive coating material for regulating the nonlinear effect of insulation resistance.

[0035] More specifically, the substrate can be tinplate or an insulating sleeve.

[0036] In practice, the mixture is applied to the outer surfaces of the tinplate and insulating sleeve using a brush and then cured at room temperature. The curing status of the coating is checked every two hours using a hardness test.

[0037] As can be seen from the above, this invention synergistically regulates the nonlinear insulation resistance characteristics of the semiconductive coating by adding conductive fillers and semiconductor fillers to a mixed epoxy resin matrix. The conductive filler provides an initial conductive path, reducing the overall resistance of the system. As the electric field increases and gradually exceeds the threshold field strength of the semiconductor filler, the current in the conductive network formed by the conductive filler will increase sharply. Under a high electric field, the semiconductor filler is activated, forming new conductive channels and dispersing the current in the conductive network of the conductive filler, thus avoiding the phenomenon of a sharp increase in current in the conductive network formed by the conductive filler under a strong electric field.

[0038] The present invention will now be described in detail with reference to several specific embodiments.

[0039] Example 1 Weigh out 50 g of phenolic F51 resin (epoxy value 0.51 eq / 100g) and 50 g of S-16 organosilicon modified epoxy resin (epoxy value 0.20 eq / 100g) respectively and mix them in a mass ratio of approximately 1:1 to obtain a mixed resin matrix. Add 0.5 g of polysiloxane defoamer BYK-066N and 2 g of polyether-modified polydimethylsiloxane leveling agent BYK-333 to the mixed resin matrix. Place the resin mixture into a reaction vessel and stir at 500 r / min at room temperature until a homogeneous liquid phase is formed. Add 5.0 g of carbon black and 10 g of silicon carbide to the homogeneous liquid phase, and continue stirring at 500 r / min for 90 min until the filler is evenly dispersed. 13.04 g of triethylenetetramine was added to the reactor as a room temperature curing agent, and the mixture was stirred at 500 r / min for 90 min to obtain a semi-conductive coating premix. The premixed liquid is applied to the surface of tinplate or insulating sleeve with a brush and cured at room temperature to obtain a semi-conductive coating material. During the curing process, the curing status of the coating is checked every two hours by a hardness test. If the hardness obtained by the test is less than the known hardness after curing, it indicates that the coating has not been fully cured. If it is equal to the known hardness after curing, it indicates that it has been fully cured.

[0040] Example 2 33 g of phenolic F51 resin (epoxy value 0.51 eq / 100g) and 67 g of S-16 silicone-modified epoxy resin (epoxy value 0.20 eq / 100g) were weighed and mixed in a mass ratio of approximately 1:1.5 to obtain a mixed resin matrix. To the mixed resin matrix, 0.5 g of polysiloxane antifoaming agent BYK-066N and 0.5 g of polyether modified polydimethylsiloxane leveling agent BYK-333 were added, and the resin mixture was placed in a reaction kettle and stirred at 450 r / min at room temperature until a uniform liquid phase was formed; To the uniform liquid phase, 3.0 g of carbon black and 20 g of silicon carbide were added, and the stirring was continued at a speed of 450 r / min for 60 min until the fillers were uniformly dispersed; To the reaction kettle, 30 g of polyether amine was added as a room temperature curing agent, and 3 g of 8030 curing accelerator was added, and the stirring was continued at a speed of 450 r / min for 60 min to obtain a semi-conductive coating premix liquid; The premix liquid was applied to the surface of a tinplate or an insulating sleeve with a brush, and cured at room temperature to obtain a semi-conductive coating material; during the curing process, the hardness test method was used to check the curing of the coating every two hours, if the hardness obtained by the test is less than the hardness after known curing, it indicates that the coating has not been completely cured, if it is equal to the hardness after known curing, it indicates that it has been completely cured.

[0041] Example 3 25 g of bisphenol F type epoxy resin 830 (epoxy value is 0.60 eq / 100g) and 75 g of E-42-epoxy resin (epoxy value is 0.4 eq / 100g) were mixed respectively, and the mass ratio was about 1:3 to obtain a mixed resin matrix; To the mixed resin matrix, 1.5 g of polysiloxane antifoaming agent BYK-066N and 2.5 g of polyether modified polydimethylsiloxane leveling agent BYK-333 were added, and the resin mixture was placed in a reaction kettle and stirred at 450 r / min at room temperature until a uniform liquid phase was formed; To the uniform liquid phase, 8.0 g of carbon black and 15 g of silicon carbide were added, and the stirring was continued at a speed of 500 r / min for 30 min until the fillers were uniformly dispersed; To the reaction kettle, 13.04 g of triethylenetetramine was added as a room temperature curing agent, and the stirring was continued at a speed of 500 r / min for 30 min to obtain a semi-conductive coating premix liquid; The premix liquid was applied to the surface of a tinplate or an insulating sleeve with a brush, and cured at room temperature to obtain a semi-conductive coating material; during the curing process, the hardness test method was used to check the curing of the coating every two hours, if the hardness obtained by the test is less than the hardness after known curing, it indicates that the coating has not been completely cured, if it is equal to the hardness after known curing, it indicates that it has been completely cured.

[0042] Example 4 Take 67 g of bisphenol F type epoxy resin 830 (epoxy value is 0.60 eq / 100g) and 33 g of S-16 E-42-epoxy resin (epoxy value is 0.4 eq / 100g) respectively, and mix them, the mass ratio of which is about 1:0.5, to obtain a mixed resin matrix; Add 1.5 g of polysiloxane antifoaming agent BYK-066N and 1.5 g of polyether modified polydimethylsiloxane leveling agent BYK-333 to the mixed resin matrix, and put the resin mixture into a reaction kettle, and stir at 450 r / min at room temperature until a uniform liquid phase is formed; Add 5.0 g of carbon black and 10 g of silicon carbide to the uniform liquid phase, and continue to stir at a speed of 450 r / min for 45 min until the fillers are uniformly dispersed; Add 10 g of diethylenetriamine as a room temperature curing agent to the reaction kettle, and continue to stir at a speed of 450 r / min for 45 min to obtain a semi-conductive coating premix liquid; Coat the premix liquid on the surface of a tinplate or an insulating sleeve with a brush, and cure at room temperature to obtain a semi-conductive coating material; during the curing process, every two hours, check the curing of the coating by a hardness test method, if the hardness obtained by the test is less than the hardness after known curing, it indicates that the coating has not been completely cured, and if it is equal to the hardness after known curing, it indicates that it has been completely cured.

[0043] Comparative Example 1 The present comparative example is a preparation method of a common semi-conductive coating, which specifically comprises the following steps: Select a single bisphenol A type epoxy resin (DER-331 epoxy resin, epoxy value is 0.5 eq / 100g) as a matrix, and put it into a reaction kettle, and add 5.0 g of carbon black and 10 g of silicon carbide to the reaction kettle, and stir at a speed of 300 r / min at room temperature for 90 min until the fillers are uniformly mixed; Add 43 g of methylhexahydrophthalic anhydride as a curing agent to the reaction kettle, and continue to stir at a speed of 500 r / min at room temperature, and after stirring for 30 min, add 1 g of dimethylbenzylamine curing agent accelerator, and continue to stir uniformly at a speed of 500 r / min to obtain a semi-conductive coating premix liquid; Coat the mixed liquid on the surface of a tinplate and an insulating sleeve with a brush, and place it in a room temperature environment for curing. During the curing process, every two hours, check the curing of the coating by a hardness test method, if the hardness obtained by the test is less than the hardness after known curing, it indicates that the coating has not been completely cured, and if it is equal to the hardness after known curing, it indicates that it has been completely cured.

[0044] Comparative Example 2 The preparation method of the comparative example of the ordinary semi-conductive coating specifically comprises the following steps: 50 g of phenolic F51 resin (epoxy value is 0.51 eq / 100g) and 50 g of S-16 silicone modified epoxy resin (epoxy value is 0.20 eq / 100g) are respectively weighed and mixed, 0.5 g of silicone defoaming agent and 2 g of leveling agent are added into the mixed resin matrix, the resin mixture is placed in a reaction kettle, stirred at a speed of 450 r / min at room temperature for 60 min until the mixture is uniform, and a uniform liquid phase is formed; After the resin components are mixed to form a uniform liquid phase, 5.0 g of carbon black is added to the reaction kettle, and the stirring is continued at a speed of 450 r / min for 60 min until the fillers are uniformly mixed; 13.04 g of triethylenetetramine is added to the reaction kettle, and the stirring is continued at a speed of 450 r / min for 60 min to obtain a semi-conductive coating premix liquid; The mixture liquid is coated on the surface of the tinplate and the insulating sleeve by a brush, and is placed in a room temperature environment for curing. During the curing process, the curing condition of the coating is checked by a hardness test method every two hours. If the hardness obtained by the test is less than the hardness of the known cured coating, it indicates that the coating has not been completely cured. If it is equal to the hardness of the known cured coating, it indicates that it has been completely cured.

[0045] Experimental example In order to verify the performance of the semi-conductive coating material prepared by the examples of the present application, comparative experiments are carried out on the semi-conductive coating samples in each example and comparative example. The specific test method is as follows: Semi-conductive coating curing condition test: according to GB / T 6739 “Pencil hardness test method for paint film”, different hardness pencils are used to start from the softest, and the coating is drawn downward at an angle of 45°, the advancing speed is about 1 cm / s, the scratch length is 1 cm, and the pencil hardness that can scratch the coating is found. The pencil hardness of the known cured coating is tested every two hours, if the hardness obtained by the test is less than the hardness of the known cured coating, it indicates that the coating has not been completely cured, if it is equal to the hardness of the known cured coating, it indicates that it has been completely cured.

[0046] Semi-conductive coating adhesion test: according to the test standard of GB / T 9286-2021 "Paints and varnishes Cross-hatch test". The test temperature is 25 ℃, and the environmental humidity is 50 %RH. The tinplate coated with semi-conductive coating is placed on a flat plate with sufficient hardness. The multi-blade cutting knife is perpendicular to the plane of the test piece, and the cutting is carried out with uniform pressure, smooth and non-vibrating method and cutting speed of 20~50 mm / s. The test piece is rotated by 90°, and the above operation is repeated on the cut incision to form a grid pattern. Then the two diagonal lines of the grid pattern are lightly brushed with a soft brush, 5 times backward and 5 times forward. Finally, test tape is applied to the entire cross-hatch area, and the tape is torn off at the smallest angle. The test is completed on at least three different positions of the test piece, and if the test results of the three positions are different, the test should be repeated on more than three positions, and all the results should be recorded. The grade is evaluated according to the proportion of the area of the paint film surface covered by the adhesive.

[0047] Semi-conductive coating flexibility test: according to the test standard of GB / T 1731-2020 "Determination of flexibility of paint film and putty film". The test temperature is 25 ℃, and the environmental humidity is 50 %RH. The tinplate coated with semi-conductive coating is tightly pressed on a 15 mm diameter shaft rod 1, and the paint film is upward, and the paint film is bent 180° (90° left and right) around the shaft rod at a smooth speed. The bending time is 2s~3 s. If the paint film does not crack and peel after bending, then the above steps are repeated on 10, 5, 4, 3, 2, 1, 0.5 mm diameter shaft rods in turn. The minimum diameter of the shaft rod through which the paint film does not crack and peel during the test is the flexibility or elasticity index. The flexibility or elasticity of the paint film can be expressed by the millimeter number of the shaft rod diameter.

[0048] Semi-conductive coating resistance test: by applying voltage to both ends of the semi-conductive coating sample, testing the current value through the semi-conductive coating sample, and calculating the equivalent resistance value of the semi-conductive coating sample according to Ohm's law based on the measured current data. The test results are as follows: Table 1 hardness of semi-conductive coating in examples 1-4 and comparative examples 1-2 at different curing times From table 1, it can be seen that the hardness of the semi-conductive coating of examples 1-4 reaches 2H within 6 h and tends to be stable, indicating that the curing time is within 6 h; while the hardness of comparative example 1 and comparative example 2 reaches only H level under the same test conditions even if the curing time is extended to 10 h, indicating that it is still not fully cured. Thus, it is shown that the semi-conductive coating material provided by the present application has a high curing rate at room temperature.

[0049] Table 2 adhesion and flexibility test results of semi-conductive coatings of examples 1-4 and comparative examples 1-2 Table 2 shows that the adhesion of the coating of the inventive examples is all 0 level, and the flexibility passes all the shaft bar tests; the adhesion of Comparative Examples 1-2 is 1 level, and the flexibility is poor. The results prove that the coating material formula of the inventive examples effectively improves the hardness, adhesion and flexibility of the coating.

[0050] Figures 1-6 Physical photos showing the adhesion test results of the semiconductive coating materials in Example 1-4 and Comparative Examples 1-2 are shown.

[0051] As can be seen from the figure, the adhesion of the coating in each inventive example is the highest level (0 level), i.e. the cutting edge is completely smooth, and there is no coating falling off; and the adhesion of the coating in the comparative examples is 1 level, which is manifested as coating falling off at the intersection of the cut and / or along the edge of the cut, and the affected intersection cutting area is obviously greater than 5%, but cannot be obviously greater than 15%. It can be seen that the coating formula provided in the present application can significantly improve the adhesion between the coating and the substrate.

[0052] Figures 7-12 Physical photos showing the flexibility test results of the semiconductive coating materials in Example 1-4 and Comparative Examples 1-2 are shown.

[0053] As can be seen from the figure, the coating in each inventive example has no cracking and peeling phenomenon after bending on each shaft bar with a diameter of 10, 5, 4, 3, 2, 1, 0.5 mm (numbered 1, 2, 3, 4, 5, 6, 7), indicating excellent flexibility; the flexibility of the coating in Comparative Example 1 does not meet the shaft bar numbered 6, i.e. the coating cracks after bending on the shaft bar of 1 mm; the flexibility of the coating in Comparative Example 2 does not meet the shaft bar numbered 7, i.e. the coating cracks after bending on the shaft bar of 0.5 mm; it can be seen that the coating formula provided in the inventive examples can significantly improve the flexibility of the coating.

[0054] Figure 13 Curves showing the resistance value of the semiconductive coating materials in Example 1-4 and Comparative Examples 1-2 changing with voltage are shown.

[0055] As can be seen from the figure, the resistance of the inventive examples presents a decreasing trend with the increase of voltage, showing certain nonlinear characteristics; but compared with the comparative examples, the resistance value decreases less. In the comparative examples, the resistance decreases more significantly with the increase of voltage. It is proved that the coating formula in the inventive examples can effectively regulate the nonlinear effect of the insulation resistance.

[0056] To sum up, the preparation method of the semi-conductive coating material for regulating the nonlinear effect of insulation resistance of the application first mixes high-performance and high-activity epoxy resin as a base, adds defoaming agent, leveling agent and other additives for stirring and dispersing, then adds conductive filler and semi-conductive filler for continuous dispersion, and finally adds normal-temperature curing agent for mixing. The feeding sequence helps to eliminate the bubbles generated in the stirring process, and prevents the mixture from starting to solidify in the stirring process due to the addition of the curing agent first, which causes the problem of being unable to be coated. At the same time, it is beneficial to promote the uniform dispersion of the conductive filler and the semi-conductor filler in the resin base and play a synergistic effect, so as to realize the effective regulation of the nonlinear effect of insulation resistance, and the process is simple and easy to implement industrially.

[0057] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application belong to the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. A semiconductive coating material for regulating the nonlinear effect of insulation resistance, characterized by, The application relates to a semi-conductive coating material for regulating the nonlinear effect of insulation resistance, which comprises the following components: a high-activity epoxy resin, a high-performance epoxy resin, a normal-temperature curing agent, a conductive filler, a semiconductor filler, a defoaming agent and a leveling agent, wherein the mass ratio of the high-activity epoxy resin to the high-performance epoxy resin is 1:(0.5-3), the epoxy value of the high-activity epoxy resin is 0.5-0.6, the epoxy value of the high-performance epoxy resin is 0.2-0.4, the adding amount of the normal-temperature curing agent is 10-30% of the total mass of the resin mixture, the adding amount of the conductive filler is 0.1-10% of the total mass of the resin mixture, the adding amount of the semiconductor filler is 10-20% of the total mass of the resin mixture, and the total adding amount of the defoaming agent and the leveling agent is 1-5% of the total mass of the resin mixture. The high-activity epoxy resin is a bisphenol F type epoxy resin or a phenolic type epoxy resin.

2. The semiconductive coating material for regulating the nonlinear effect of insulation resistance according to claim 1, characterized in that, The high-performance epoxy resin is a bisphenol A type epoxy resin or a silicone-modified epoxy resin.

3. The semiconductive coating material for regulating the nonlinear effect of insulation resistance according to claim 1, characterized by, The normal-temperature curing agent is at least one selected from triethylene tetramine, polyether amine, ethylenediamine and diethylene triamine.

4. The semiconductive coating material for regulating the nonlinear effect of insulation resistance according to claim 1, wherein When the normal-temperature curing agent is triethylene tetramine, ethylenediamine or diethylene triamine, the adding amount is 10-15% of the total mass of the resin mixture.

5. The semiconductive coating material for regulating the nonlinear effect of insulation resistance according to claim 4, characterized in that, When the normal-temperature curing agent is polyether amine, the adding amount is 25-30% of the total mass of the resin mixture, and a curing accelerator accounting for 2-3% of the total mass of the resin mixture is further added.

6. The semiconductive coating material for regulating the nonlinear effect of insulation resistance according to claim 4, characterized by, The application further discloses a preparation method of the semi-conductive coating material for regulating the nonlinear effect of insulation resistance, which comprises the following steps:

7. A method for producing a semiconductive coating material for regulating the nonlinear effect of insulation resistance, characterized by, The high-activity epoxy resin and the high-performance epoxy resin are mixed in a mass ratio of 1:(0.5-3) to obtain a mixed resin matrix, wherein the epoxy value of the high-activity epoxy resin is 0.5-0.6, and the epoxy value of the high-performance epoxy resin is 0.2-0.4; The defoaming agent and the leveling agent are added into the mixed resin matrix, and stirring is carried out at a preset rotating speed under normal temperature until a uniform liquid phase is formed; wherein the total adding amount of the defoaming agent and the leveling agent is 1-5% of the total mass of the resin mixture; The conductive filler and the semiconductor filler are added into the uniform liquid phase, and stirring is continuously carried out until the fillers are uniformly dispersed; wherein the adding amount of the conductive filler is 0.1-10% of the total mass of the resin mixture, and the adding amount of the semiconductor filler is 10-20% of the total mass of the resin mixture; The normal-temperature curing agent is added into the above mixture, the adding amount of the normal-temperature curing agent is 10-30% of the total mass of the resin mixture, and stirring is continuously carried out to obtain a semi-conductive coating premix liquid; The semi-conductive coating premix liquid is coated on the surface of a substrate, and curing is carried out under normal temperature to obtain the semi-conductive coating material for regulating the nonlinear effect of insulation resistance. The conductive filler is at least one selected from carbon black, carbon nanotube and graphene.

8. The method of claim 7, wherein the semi-conductive coating material is prepared by mixing the conductive material and the insulating material in a ratio of 1 : 1 to 1 :

10. The semiconductor filler is at least one selected from silicon carbide, titanium dioxide and zinc oxide.

9. The method of claim 7, wherein the semi-conductive coating material is prepared by mixing a conductive material and a binder, and then coating the mixture on a surface of a substrate. The adding amount of the defoaming agent is 0.5% of the total mass of the resin mixture, and the adding amount of the leveling agent is 2% of the total mass of the resin mixture.

10. The method of claim 7, wherein the semi-conductive coating material is prepared by mixing a conductive material and a binder, and then coating the mixture on a surface of a substrate. ​

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