Electrostatic spraying process for flame-retardant electrical cabinet metal plate

Abstract

The invention relates to an electrostatic spraying process for a flame-retardant electrical cabinet metal plate, and belongs to the technical field of electrical cabinet surface treatment. The electrical cabinet sheet metal part is sequentially subjected to degreasing, acid pickling, phosphating, water washing and drying treatment; the preparation method comprises the following steps: putting epoxy resin, a modified aliphatic amine curing agent, 4-ferrocenyl butyl methacrylate, 4, 4 '-dimercaptodiphenyl sulfide, benzoyl peroxide, a composite flame retardant, a pigment filler, a carboxyl-terminated nitrile rubber flexibilizer, an acrylate leveling agent, an antioxidant and a diluent into a mixing machine, and mixing to obtain plastic spraying powder; the pretreated sheet metal part is placed in a spraying room, electrostatic spraying, curing forming and aftertreatment are conducted on the surface of the sheet metal part, and the flame-retardant electrical cabinet sheet metal part is obtained; the prepared plastic spraying coating is high in oxygen index, the vertical combustion grade reaches the V-0 grade, the flame retardant effect is excellent, and combustion accidents caused by high temperature and electric sparks of an electrical cabinet can be effectively prevented.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrical cabinet surface treatment, in particular to a static electrostatic spraying process for flame-retardant electrical cabinet sheet metal. BACKGROUND

[0002] As a core device for installing electrical components and lines in the power system, electrical cabinets are widely used in industrial production, building, power transmission and other fields. Sheet metal parts are the main structural components of electrical cabinets, and the performance of the surface protective coating directly affects the service life, safety and stability, and weather resistance of the electrical cabinet. The plastic spraying coating has good insulation, corrosion resistance, decoration and convenient construction, and has become the mainstream way of surface treatment of electrical cabinet sheet metal.

[0003] Chinese patent CN117531672B discloses a spraying process for switch cabinet sheet metal shell, relating to the technical field of sheet metal spraying, comprising the following steps: pre-degreasing, degreasing, first water washing, phosphating, second water washing, air box drying, spraying and curing; the spraying equipment comprises a support frame, a fixing frame, a conveying plate, a hook, a lifting plate, a spraying head, a fixing frame and an opening and closing mechanism.

[0004] Chinese patent CN119634125A relates to the technical field of metal surface treatment and discloses a sheet metal part spraying and spraying device and process, comprising a spraying chamber and a conveying mechanism, the spraying chamber is arranged in the middle of the conveying mechanism, the top of the spraying chamber is provided with a distribution plate, the inside of the spraying chamber is provided with two spraying mechanisms near one side of the distribution plate, the inside of each spraying mechanism is provided with a plurality of uniformly distributed spraying guns, the side of the spraying gun near the distribution plate is respectively provided with a gas tank and a conveying pipe, the side of the conveying pipe away from the spraying gun is provided with a pump body, and the rear side of the spraying chamber is provided with a paint storage tank.

[0005] The existing electrical cabinet sheet metal spraying formula focuses on corrosion resistance and decoration, but the flame retardant performance is insufficient, the coating oxygen index is low, the vertical burning grade is low, and it is difficult to meet the safety requirements under complex conditions such as high pressure and high temperature. SUMMARY

[0006] In order to solve the above problems, the present application provides a static electrostatic spraying process for flame-retardant electrical cabinet sheet metal, and the operation steps are as follows, according to the mass fraction: S1 sheet metal pretreatment: the electrical cabinet sheet metal parts are sequentially degreased, pickled, phosphated, washed and dried; S2 plastic spraying preparation: 40-55 parts of epoxy resin, 8-15 parts of modified aliphatic amine curing agent T-31, 0.3-0.8 parts of 4-dicyclohexylbutyl crotonate, 0.05-0.3 parts of 4, 4'-dithio diphenyl sulfide, 0.02-0.2 parts of benzoyl peroxide, 18-28 parts of composite flame retardant, 10-18 parts of pigment and filler, 2-5 parts of carboxyl-terminated butyl nitrile rubber toughening agent, 0.5-1.5 parts of acrylate leveling agent, 0.3-0.8 parts of antioxidant, 5-10 parts of diluent, are put into the mixer for mixing, grinding, to get the plastic powder; S3 electrostatic spraying: the pretreated sheet metal part is placed in the spraying room, and the surface of the sheet metal part is electrostatically sprayed, and the dry film thickness is 60-80 μm; S4 curing forming: after the sprayed sheet metal part is sent into the curing furnace for curing, it is naturally cooled to room temperature; S6 post-treatment: polishing, dust removal and surface defect removal are carried out on the cured sheet metal part to obtain the flame-retardant electrical cabinet sheet metal part.

[0007] Further, the S1 degreasing adopts sodium metasilicate alkaline degreasing agent, the degreasing temperature is 50-60℃, the degreasing time is 15-20min; the pickling adopts 10-15wt% hydrochloric acid solution, the pickling time is 5-8min; the phosphating adopts zinc-based phosphating solution, the phosphating temperature is 35-45℃, the phosphating time is 10-15min; the drying temperature is 120-140℃, and the drying time is 20-30min.

[0008] Further, the epoxy resin is one of bisphenol A type epoxy resins E-44, E-54 and E-51.

[0009] Further, the composite flame retardant is a complex system of expanded graphite and aluminum hydroxide, and the mass ratio is 1:2-4.

[0010] Further, the pigment and filler are a complex system of titanium dioxide, talc and mica powder, and the mass ratio is 2:1:1.

[0011] Further, the diluent is one of toluene, xylene, butyl acetate and ethyl acetate.

[0012] Further, the rotating speed of the S2 mixer is 800-1200r / min, the temperature is 40-50℃, and the mixing time is 30-45min.

[0013] Further, the S2 grinding is to a particle size of 30-40 μm.

[0014] Further, the voltage of the S3 electrostatic spraying is 60-80kV, the atomizing gas pressure is 0.3-0.5MPa, and the spraying distance is 20-30cm.

[0015] Further, the S4 curing temperature is 180-200 DEG C, and the time is 20-30 min.

[0016] Reaction mechanism: 4,4'-dimercaptodiphenyl sulfide as a thiol donor, its containing thiol can occur ring opening reaction with epoxy group of epoxy resin, at the same time with 4-ferrocenyl butyl methacrylate in the addition reaction of isobutene double bond; 4-ferrocenyl butyl methacrylate as a new type of functional monomer, not only provides reactive site, its unique structure can also optimize the crosslinking environment of coating; The amino group of modified fatty amine curing agent T-31 synchronously occurs ring opening reaction with epoxy group, and three kinds of reactions cooperatively construct a dense and stable crosslinked coating network; The composite flame retardant is uniformly dispersed in the network, and forms a flame retardant barrier through physical barrier and chemical inhibition at high temperature, and the flame retardant efficiency of the coating is synergistically enhanced with the crosslinked structure and the characteristics of the two functional monomers.

[0017] Technical effects: Compared with the prior art, the electrostatic plastic spraying process for the flame-retardant electrical cabinet sheet metal of the present application has the following remarkable effects: 1. The novel monomers of 4-ferrocenyl butyl methacrylate and 4,4'-dimercaptodiphenyl sulfide are introduced, and multiple reactions occur between the two and the resin and the curing agent, which not only improves the combination stability of the flame-retardant components, but also gives the coating a more optimal structural density, and the flame-retardant performance is greatly improved.

[0018] 2. The crosslinking effect of 4,4'-dimercaptodiphenyl sulfide and the structural advantages of 4-ferrocenyl butyl methacrylate, combined with the halogen-free and environmentally friendly characteristics of the composite flame retardant, make the coating not only have excellent flame-retardant performance, but also have insulation and corrosion resistance, which meets the safety requirements of electrical cabinets under complex working conditions.

[0019] 3. The crosslinked network constructed by the two functional monomers enhances the interfacial adhesion between the coating and the sheet metal part, reduces the risk of coating falling off and damage, and the unique structure of 4-ferrocenyl butyl methacrylate helps to improve the thermal stability of the coating, further prolonging the service life of the electrical cabinet. DETAILED DESCRIPTION

[0020] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the following embodiments and comparative examples are described in detail: 1. Oxygen index: detected according to GB / T2406.2-2009 "Determination of the Burning Behavior of Plastics by the Oxygen Index Method Part 2: Room Temperature Test".

[0021] 2. Vertical burning grade: detected according to GB / T2408-2021 "Determination of the Burning Behavior of Plastics by the Horizontal and Vertical Methods", and the grade is evaluated. Example 1

[0022] An electrostatic powder coating process for flame-retardant electrical cabinet sheet metal, the operation steps of which are as follows: S1 Sheet Metal Pre-treatment: The sheet metal parts of the electrical cabinet are degreased, pickled, phosphated, washed, and dried in sequence; S2 powder coating preparation: 40g epoxy resin, 8g modified fatty amine curing agent T-31, 0.3g 4-ferrocene-based butyl isobutylene ester (CAS: 1352832-96-2), 0.05g 4,4'-dimercaptodiphenyl sulfide (CAS: 19362-77-7), 0.02g benzoyl peroxide, 18g composite flame retardant, 10g pigments and fillers, 2g carboxyl-terminated nitrile rubber toughening agent, 0.5g acrylate leveling agent BYK-358N, 0.3g antioxidant 1010, and 5g diluent are added to a mixer, mixed, and ground to obtain powder coating powder; S3 electrostatic spraying: The pre-treated sheet metal parts are placed in the spraying booth and electrostatic spraying is performed on the surface of the sheet metal parts, with a dry film thickness of 60μm. S4 Curing and Molding: After the sprayed sheet metal parts are placed in the curing oven for curing, they are naturally cooled to room temperature; S6 Post-processing: Grinding and dust removal are performed on the cured sheet metal parts to remove surface defects and obtain flame-retardant electrical cabinet sheet metal parts.

[0023] The S1 degreasing uses an alkaline sodium metasilicate degreasing agent, with a degreasing temperature of 50℃ and a degreasing time of 15 min; pickling uses a 10wt% hydrochloric acid solution, with a pickling time of 5 min; phosphating uses a zinc-based phosphating solution, with a phosphating temperature of 35℃ and a phosphating time of 10 min; and drying temperature is 120℃ and drying time is 20 min.

[0024] The epoxy resin is bisphenol A type epoxy resin E-44.

[0025] The composite flame retardant is a compound system of expanded graphite and aluminum hydroxide, with a mass ratio of 1:2.

[0026] The pigment and filler are a compound system of titanium dioxide, talc, and mica powder in a mass ratio of 2:1:1.

[0027] The diluent is toluene.

[0028] The S2 mixer has a rotation speed of 800 r / min, a temperature of 40℃, and a mixing time of 30 min.

[0029] The S2 is ground to a particle size of 40μm.

[0030] The voltage of the S3 electrostatic spraying is 60kV, the atomizing pressure is 0.3MPa, and the spraying distance is 20cm.

[0031] The curing temperature of S4 is 180℃ and the curing time is 20 minutes. Example 2

[0032] An electrostatic powder coating process for flame-retardant electrical cabinet sheet metal, the operation steps of which are as follows: S1 Sheet Metal Pre-treatment: The sheet metal parts of the electrical cabinet are degreased, pickled, phosphated, washed, and dried in sequence; S2 powder coating preparation: 45g epoxy resin, 10g modified fatty amine curing agent T-31, 0.4g 4-ferrocene-based butyl isobutylene ester (CAS: 1352832-96-2), 0.1g 4,4'-dimercaptodiphenyl sulfide (CAS No. 19362-77-7), 0.1g benzoyl peroxide, 22g composite flame retardant, 12g pigments and fillers, 3g carboxyl-terminated nitrile rubber toughening agent, 0.8g acrylate leveling agent BYK-358N, 0.4g antioxidant 1010, and 6g diluent are added to a mixer, mixed, and ground to obtain powder coating powder; S3 electrostatic spraying: The pre-treated sheet metal parts are placed in the spraying booth and electrostatic spraying is performed on the surface of the sheet metal parts, with a dry film thickness of 70μm. S4 Curing and Molding: After the sprayed sheet metal parts are placed in the curing oven for curing, they are naturally cooled to room temperature; S6 Post-processing: Grinding and dust removal are performed on the cured sheet metal parts to remove surface defects and obtain flame-retardant electrical cabinet sheet metal parts.

[0033] The S1 degreasing uses an alkaline sodium metasilicate degreasing agent, with a degreasing temperature of 55℃ and a degreasing time of 15 min; pickling uses a 10wt% hydrochloric acid solution, with a pickling time of 6 min; phosphating uses a zinc-based phosphating solution, with a phosphating temperature of 40℃ and a phosphating time of 10 min; and drying temperature is 125℃ and drying time is 25 min.

[0034] The epoxy resin is bisphenol A type epoxy resin E-54.

[0035] The composite flame retardant is a compound system of intumescent graphite and aluminum hydroxide, with a mass ratio of 1:3.

[0036] The pigment and filler are a compound system of titanium dioxide, talc, and mica powder in a mass ratio of 2:1:1.

[0037] The diluent is xylene.

[0038] The S2 mixer has a rotation speed of 900 r / min, a temperature of 45℃, and a mixing time of 35 min.

[0039] The S2 is ground to a particle size of 35μm.

[0040] The voltage of the S3 electrostatic spraying is 70kV, the atomizing pressure is 0.4MPa, and the spraying distance is 25cm.

[0041] The curing temperature of S4 is 185℃ and the curing time is 25 minutes. Example 3

[0042] An electrostatic powder coating process for flame-retardant electrical cabinet sheet metal, the operation steps of which are as follows: S1 Sheet Metal Pre-treatment: The sheet metal parts of the electrical cabinet are degreased, pickled, phosphated, washed, and dried in sequence; S2 powder coating preparation: 50g epoxy resin, 13g modified fatty amine curing agent T-31, 0.7g 4-ferrocene-based butyl isobutylene ester (CAS: 1352832-96-2), 0.2g 4,4'-dimercaptodiphenyl sulfide (CAS No. 19362-77-7), 0.15g benzoyl peroxide, 25g composite flame retardant, 16g pigments and fillers, 4g carboxyl-terminated nitrile rubber toughening agent, 1.3g acrylate leveling agent BYK-358N, 0.7g antioxidant 1010, and 8g diluent are added to a mixer, mixed, and ground to obtain powder coating powder; S3 electrostatic spraying: The pre-treated sheet metal parts are placed in the spraying booth and electrostatic spraying is performed on the surface of the sheet metal parts, with a dry film thickness of 70μm. S4 Curing and Molding: After the sprayed sheet metal parts are placed in the curing oven for curing, they are naturally cooled to room temperature; S6 Post-processing: Grinding and dust removal are performed on the cured sheet metal parts to remove surface defects and obtain flame-retardant electrical cabinet sheet metal parts.

[0043] The S1 degreasing uses an alkaline sodium metasilicate degreasing agent at a temperature of 55°C for 20 minutes; pickling uses a 15wt% hydrochloric acid solution for 7 minutes; phosphating uses a zinc-based phosphating solution at a temperature of 40°C for 15 minutes; and drying is carried out at a temperature of 135°C for 25 minutes.

[0044] The epoxy resin is bisphenol A type epoxy resin E-54.

[0045] The composite flame retardant is a compound system of intumescent graphite and aluminum hydroxide, with a mass ratio of 1:3.

[0046] The pigment and filler are a compound system of titanium dioxide, talc, and mica powder in a mass ratio of 2:1:1.

[0047] The diluent is butyl acetate.

[0048] The S2 mixer has a rotation speed of 1100 r / min, a temperature of 45℃, and a mixing time of 40 min.

[0049] The S2 is ground to a particle size of 30μm.

[0050] The voltage of the S3 electrostatic spraying is 70kV, the atomizing pressure is 0.4MPa, and the spraying distance is 25cm.

[0051] The curing temperature of S4 is 195℃ and the curing time is 25 minutes. Example 4

[0052] An electrostatic powder coating process for flame-retardant electrical cabinet sheet metal, the operation steps of which are as follows: S1 Sheet Metal Pre-treatment: The sheet metal parts of the electrical cabinet are degreased, pickled, phosphated, washed, and dried in sequence; S2 powder coating preparation: 55g epoxy resin, 15g modified fatty amine curing agent T-31, 0.8g 4-ferrocene-based butyl isobutylene ester (CAS: 1352832-96-2), 0.3g 4,4'-dimercaptodiphenyl sulfide (CAS No. 19362-77-7), 0.2g benzoyl peroxide, 28g composite flame retardant, 18g pigments and fillers, 5g carboxyl-terminated nitrile rubber toughening agent, 1.5g acrylate leveling agent BYK-358N, 0.8g antioxidant 1010, and 10g diluent are added to a mixer, mixed, and ground to obtain powder coating powder; S3 electrostatic spraying: The pre-treated sheet metal parts are placed in the spraying booth and electrostatic spraying is performed on the surface of the sheet metal parts, with a dry film thickness of 80μm. S4 Curing and Molding: After the sprayed sheet metal parts are placed in the curing oven for curing, they are naturally cooled to room temperature; S6 Post-processing: Grinding and dust removal are performed on the cured sheet metal parts to remove surface defects and obtain flame-retardant electrical cabinet sheet metal parts.

[0053] The S1 degreasing process uses an alkaline sodium metasilicate degreasing agent at a temperature of 60°C for 20 minutes; pickling uses a 15wt% hydrochloric acid solution for 8 minutes; phosphating uses a zinc-based phosphating solution at a temperature of 45°C for 15 minutes; and drying is carried out at a temperature of 140°C for 30 minutes.

[0054] The epoxy resin is bisphenol A type epoxy resin E-51.

[0055] The composite flame retardant is a compound system of intumescent graphite and aluminum hydroxide, with a mass ratio of 1:4.

[0056] The pigment and filler are a compound system of titanium dioxide, talc, and mica powder in a mass ratio of 2:1:1.

[0057] The diluent is ethyl acetate.

[0058] The S2 mixer has a rotation speed of 1200 r / min, a temperature of 50℃, and a mixing time of 45 min.

[0059] The S2 is ground to a particle size of 30μm.

[0060] The voltage of the S3 electrostatic spraying is 80kV, the atomizing pressure is 0.5MPa, and the spraying distance is 30cm.

[0061] The curing temperature of S4 is 200℃ and the curing time is 30 minutes.

[0062] Comparative Example 1 An electrostatic powder coating process for flame-retardant electrical cabinet sheet metal, the operation steps of which are as follows: S1 Sheet Metal Pre-treatment: The sheet metal parts of the electrical cabinet are degreased, pickled, phosphated, washed, and dried in sequence; S2 powder coating preparation: 40g epoxy resin, 8g modified fatty amine curing agent T-31, 0.02g benzoyl peroxide, 18g composite flame retardant, 10g pigments and fillers, 2g carboxyl-terminated nitrile rubber toughening agent, 0.5g acrylate leveling agent BYK-358N, 0.3g antioxidant 1010, and 5g diluent are put into a mixer, mixed, and ground to obtain powder coating powder; S3 electrostatic spraying: The pre-treated sheet metal parts are placed in the spraying booth and electrostatic spraying is performed on the surface of the sheet metal parts, with a dry film thickness of 60μm. S4 Curing and Molding: After the sprayed sheet metal parts are placed in the curing oven for curing, they are naturally cooled to room temperature; S6 Post-processing: Grinding and dust removal are performed on the cured sheet metal parts to remove surface defects and obtain flame-retardant electrical cabinet sheet metal parts.

[0063] The S1 degreasing uses an alkaline sodium metasilicate degreasing agent, with a degreasing temperature of 50℃ and a degreasing time of 15 min; pickling uses a 10wt% hydrochloric acid solution, with a pickling time of 5 min; phosphating uses a zinc-based phosphating solution, with a phosphating temperature of 35℃ and a phosphating time of 10 min; and drying temperature is 120℃ and drying time is 20 min.

[0064] The epoxy resin is bisphenol A type epoxy resin E-44.

[0065] The composite flame retardant is a compound system of expanded graphite and aluminum hydroxide, with a mass ratio of 1:2.

[0066] The pigment and filler are a compound system of titanium dioxide, talc, and mica powder in a mass ratio of 2:1:1.

[0067] The diluent is toluene.

[0068] The S2 mixer has a rotation speed of 800 r / min, a temperature of 40℃, and a mixing time of 30 min.

[0069] The S2 is ground to a particle size of 40μm.

[0070] The voltage of the S3 electrostatic spraying is 60kV, the atomizing pressure is 0.3MPa, and the spraying distance is 20cm.

[0071] The curing temperature of S4 is 180℃ and the curing time is 20 minutes.

[0072] Comparative Example 2 An electrostatic powder coating process for flame-retardant electrical cabinet sheet metal, the operation steps of which are as follows: S1 Sheet Metal Pre-treatment: The sheet metal parts of the electrical cabinet are degreased, pickled, phosphated, washed, and dried in sequence; S2 powder coating preparation: 40g epoxy resin, 8g modified fatty amine curing agent T-31, 0.05g 4,4'-dimercaptodiphenyl sulfide (CAS No. 19362-77-7), 0.02g benzoyl peroxide, 18g composite flame retardant, 10g pigments and fillers, 2g carboxyl-terminated nitrile rubber toughening agent, 0.5g acrylate leveling agent BYK-358N, 0.3g antioxidant 1010, and 5g diluent are added to a mixer and mixed and ground to obtain powder coating powder; S3 electrostatic spraying: The pre-treated sheet metal parts are placed in the spraying booth and electrostatic spraying is performed on the surface of the sheet metal parts, with a dry film thickness of 60μm. S4 Curing and Molding: After the sprayed sheet metal parts are placed in the curing oven for curing, they are naturally cooled to room temperature; S6 Post-processing: Grinding and dust removal are performed on the cured sheet metal parts to remove surface defects and obtain flame-retardant electrical cabinet sheet metal parts.

[0073] The S1 degreasing uses an alkaline sodium metasilicate degreasing agent, with a degreasing temperature of 50℃ and a degreasing time of 15 min; pickling uses a 10wt% hydrochloric acid solution, with a pickling time of 5 min; phosphating uses a zinc-based phosphating solution, with a phosphating temperature of 35℃ and a phosphating time of 10 min; and drying temperature is 120℃ and drying time is 20 min.

[0074] The epoxy resin is bisphenol A type epoxy resin E-44.

[0075] The composite flame retardant is a compound system of expanded graphite and aluminum hydroxide, with a mass ratio of 1:2.

[0076] The pigment and filler are a compound system of titanium dioxide, talc, and mica powder in a mass ratio of 2:1:1.

[0077] The diluent is toluene.

[0078] The S2 mixer has a rotation speed of 800 r / min, a temperature of 40℃, and a mixing time of 30 min.

[0079] The S2 is ground to a particle size of 40μm.

[0080] The voltage of the S3 electrostatic spraying is 60kV, the atomizing pressure is 0.3MPa, and the spraying distance is 20cm.

[0081] The curing temperature of S4 is 180℃ and the curing time is 20 minutes.

[0082] Comparative Example 3 An electrostatic powder coating process for flame-retardant electrical cabinet sheet metal, the operation steps of which are as follows: S1 Sheet Metal Pre-treatment: The sheet metal parts of the electrical cabinet are degreased, pickled, phosphated, washed, and dried in sequence; S2 powder coating preparation: 40g epoxy resin, 8g modified fatty amine curing agent T-31, 0.3g 4-ferrocene-based butyl isobutylene ester (CAS: 1352832-96-2), 0.02g benzoyl peroxide, 18g composite flame retardant, 10g pigments and fillers, 2g carboxyl-terminated nitrile rubber toughening agent, 0.5g acrylate leveling agent BYK-358N, 0.3g antioxidant 1010, and 5g diluent are added to a mixer and mixed and ground to obtain powder coating powder; S3 electrostatic spraying: The pre-treated sheet metal parts are placed in the spraying booth and electrostatic spraying is performed on the surface of the sheet metal parts, with a dry film thickness of 60μm. S4 Curing and Molding: After the sprayed sheet metal parts are placed in the curing oven for curing, they are naturally cooled to room temperature; S6 Post-processing: Grinding and dust removal are performed on the cured sheet metal parts to remove surface defects and obtain flame-retardant electrical cabinet sheet metal parts.

[0083] The S1 degreasing uses an alkaline sodium metasilicate degreasing agent, with a degreasing temperature of 50℃ and a degreasing time of 15 min; pickling uses a 10wt% hydrochloric acid solution, with a pickling time of 5 min; phosphating uses a zinc-based phosphating solution, with a phosphating temperature of 35℃ and a phosphating time of 10 min; and drying temperature is 120℃ and drying time is 20 min.

[0084] The epoxy resin is bisphenol A type epoxy resin E-44.

[0085] The composite flame retardant is a compound system of expanded graphite and aluminum hydroxide, with a mass ratio of 1:2.

[0086] The pigment and filler are a compound system of titanium dioxide, talc, and mica powder in a mass ratio of 2:1:1.

[0087] The diluent is toluene.

[0088] The S2 mixer has a rotation speed of 800 r / min, a temperature of 40℃, and a mixing time of 30 min.

[0089] The S2 is ground to a particle size of 40μm.

[0090] The voltage of the S3 electrostatic spraying is 60kV, the atomizing pressure is 0.3MPa, and the spraying distance is 20cm.

[0091] The curing temperature of S4 is 180℃ and the curing time is 20 minutes.

[0092] Table 1 shows the oxygen index and vertical flammability test results of the powder coatings in the examples and comparative examples. Oxygen index (%) Vertical burn rating Example 1 34.3 V-0 Example 2 34.5 V-0 Example 3 35.0 V-0 Example 4 35.2 V-0 Comparative Example 1 25.1 V-2 Comparative Example 2 29.8 V-1 Comparative Example 3 30.6 V-1 The powder-coated coating of the embodiment significantly outperformed the comparative example in both oxygen index and vertical flammability rating. The core reason lies in the synergistic design of 4,4'-dimercaptodiphenyl sulfide and 4-ferrocene-butyl isobutylene ester in the formulation. 4-ferrocene-butyl isobutylene ester, as a novel monomer, precisely controls the triple reaction (mercapto-epoxy ring-opening, mercapto-isobutylene addition, and epoxy-amino ring-opening) with 4,4'-dimercaptodiphenyl sulfide, epoxy resin, and curing agent. This not only constructs a stable and dense cross-linked network but also ensures the uniform dispersion and efficient performance of the composite flame retardant. This successfully addresses the shortcomings of traditional formulations in terms of insufficient flame retardant performance, achieving a simultaneous improvement in both the flame retardancy and overall protective performance of the coating.

[0093] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An electrostatic powder coating process for flame-retardant electrical cabinet sheet metal, characterized in that, Includes the following steps, measured in parts by weight: S1 Sheet Metal Pre-treatment: The sheet metal parts of the electrical cabinet are degreased, pickled, phosphated, washed, and dried in sequence; S2 powder coating preparation: 40-55 parts epoxy resin, 8-15 parts modified fatty amine curing agent, 0.3-0.8 parts 4-ferrocene-based butyl isobutylene ester, 0.05-0.3 parts 4,4'-dimercaptodiphenyl sulfide, 0.02-0.2 parts benzoyl peroxide, 18-28 parts composite flame retardant, 10-18 parts pigments and fillers, 2-5 parts carboxyl-terminated butadiene-acrylonitrile rubber toughening agent, 0.5-1.5 parts acrylate leveling agent, 0.3-0.8 parts antioxidant, and 5-10 parts diluent are added to a mixer and mixed and ground to obtain powder coating powder; S3 electrostatic spraying: The pre-treated sheet metal parts are placed in the spraying booth and electrostatic spraying is performed on the surface of the sheet metal parts. The dry film thickness is 60-80μm. S4 Curing and Molding: After the sprayed sheet metal parts are placed in the curing oven for curing, they are naturally cooled to room temperature; S6 Post-processing: Grinding and dust removal are performed on the cured sheet metal parts to remove surface defects and obtain flame-retardant electrical cabinet sheet metal parts.

2. The electrostatic powder coating process for a flame-retardant electrical cabinet sheet metal according to claim 1, characterized in that: The S1 degreasing process uses an alkaline sodium metasilicate degreasing agent at a temperature of 50-60℃ for 15-20 minutes; pickling uses a 10-15wt% hydrochloric acid solution for 5-8 minutes; phosphating uses a zinc-based phosphating solution at a temperature of 35-45℃ for 10-15 minutes; and drying is carried out at a temperature of 120-140℃ for 20-30 minutes.

3. The electrostatic powder coating process for a flame-retardant electrical cabinet sheet metal according to claim 1, characterized in that: The epoxy resin is one of bisphenol A type epoxy resins E-44, E-54, and E-51.

4. The electrostatic powder coating process for a flame-retardant electrical cabinet sheet metal according to claim 1, characterized in that: The composite flame retardant is a compound system of intumescent graphite and aluminum hydroxide, with a mass ratio of 1:2-4.

5. The electrostatic powder coating process for a flame-retardant electrical cabinet sheet metal according to claim 1, characterized in that: The pigment and filler are a compound system of titanium dioxide, talc, and mica powder in a mass ratio of 2:1:

1.

6. The electrostatic powder coating process for a flame-retardant electrical cabinet sheet metal according to claim 1, characterized in that: The diluent is one of toluene, xylene, butyl acetate, and ethyl acetate.

7. The electrostatic powder coating process for a flame-retardant electrical cabinet sheet metal according to claim 1, characterized in that: The S2 mixer has a rotation speed of 800-1200 r / min, a temperature of 40-50℃, and a mixing time of 30-45 min.

8. The electrostatic powder coating process for a flame-retardant electrical cabinet sheet metal according to claim 1, characterized in that: The S2 is ground to a particle size of 30-40μm.

9. The electrostatic powder coating process for a flame-retardant electrical cabinet sheet metal according to claim 1, characterized in that: The voltage of the S3 electrostatic spraying is 60-80kV, the atomizing gas pressure is 0.3-0.5MPa, and the spraying distance is 20-30cm.

10. The electrostatic powder coating process for a flame-retardant electrical cabinet sheet metal according to claim 1, characterized in that: The curing temperature of S4 is 180-200℃, and the curing time is 20-30 minutes.