Stone-impact-resistant insulating powder coating for automobile battery tray and preparation method of stone-impact-resistant insulating powder coating

Abstract

The invention relates to the technical field of insulating powder coatings, in particular to a stone-impact-resistant insulating powder coating for an automobile battery tray and a preparation method of the stone-impact-resistant insulating powder coating. The coating is prepared from the following raw materials in parts by weight: epoxy resin A, epoxy resin B, nitrile rubber modified epoxy resin, a phenolic resin curing agent, quartz powder, a flatting agent, pigment, a curing accelerator, an anti-settling agent, an adhesion promoter, a defoaming agent and an electricity increasing agent. The coating is synchronously endowed with ultrahigh insulativity and top-level stone impact resistance through single-time coating, and a secondary construction link is thoroughly canceled; zero VOC emission is realized by adopting a solid powder system; the special toughening resin and the gradient curing process enable the coating to have both rigid protection and toughness buffering, the actually measured stone impact resistance grade is greater than 9 grade, the breakdown voltage meets 6kV, and the leakage current is 1t; and the high-voltage battery system perfectly meets the strict requirements of the high-voltage battery system of the electric vehicle on safety and environmental protection, and solves the technical defects in the traditional scheme.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of insulating powder coating, in particular to an anti-stone impact insulating powder coating for automobile battery tray and a preparation method thereof. BACKGROUND

[0002] The automobile battery tray is a metal structural member for carrying and fixing the power battery pack in the chassis system of the electric vehicle. Its core function is to provide mechanical support, collision protection and heat management channel integration for the battery module, and at the same time, it needs to isolate the electrical conduction risk between the high-voltage battery system and the vehicle body. The automobile battery tray must be treated by film coating process, because it is exposed to complex working conditions for a long time: road stone impact during driving can easily cause corrosion and perforation of the metal substrate, condensation water vapor penetration may cause battery short circuit, and the high-voltage battery system requires the tray to have a permanent insulation barrier to avoid electric leakage accidents, so the coating needs to meet the three protection requirements of anti-mechanical damage, environmental corrosion resistance and high insulation at the same time.

[0003] Generally, the traditional automobile battery tray adopts a double-coating system of ordinary insulating coating and PVC anti-stone impact coating. This scheme has the following defects: the insulating layer and the anti-stone impact layer need to be applied twice and need to be cured and waited in between, which is complex and time-consuming, resulting in low production efficiency; the PVC coating contains a large amount of volatile organic solvents, which releases VOC pollutants during high-temperature curing; the adhesion of the interface of the double-layer structure is weakened, and it is easy to delaminate and fail in the long-term vibration environment.

[0004] Based on this, the present application provides an anti-stone impact insulating powder coating for automobile battery tray and a preparation method thereof to solve the above-mentioned technical problems. SUMMARY

[0005] The purpose of the present application is to provide an anti-stone impact insulating powder coating for automobile battery tray and a preparation method thereof to solve the problems mentioned in the background art.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical scheme: The present application provides an anti-stone impact insulating powder coating for automobile battery tray, which is composed of the following raw materials by weight: epoxy resin A: 15-20 parts, epoxy resin B: 35-40 parts, nitrile rubber modified epoxy resin: 5-10 parts, phenolic resin curing agent: 10-13 parts, quartz powder: 20-35 parts, leveling agent: 0.8-1.2 parts, pigment: 1-5 parts, curing accelerator: 0.3-0.8 parts, anti-settling agent: 0.5-1 parts, adhesion enhancer: 0.3-0.6 parts, defoaming agent: 0.3-0.6 parts and electric enhancer: 0.3-0.8 parts; The epoxy resin A is an epoxy resin with an epoxy equivalent weight of 850-900; the epoxy resin B is an epoxy resin with an epoxy equivalent weight of 1700-2000; the nitrile rubber modified epoxy resin is a modified epoxy resin with an epoxy equivalent weight of 750-800; the pigment is specifically rutile titanium dioxide; the curing accelerator is specifically 2-methylimidazole; the anti-settling agent is specifically fumed silica; the adhesion enhancer is specifically a silane coupling agent; the defoaming agent is specifically benzoin; and the electricity enhancer is specifically a tetraalkylammonium salt.

[0007] Preferably, the preparation steps of the epoxy resin A are as follows: A1. Bisphenol A and epichlorohydrin are put into a reaction kettle at a molar ratio of 1:1.38, dissolved by heating to 75°C, and then 50% sodium hydroxide solution is added dropwise at a constant temperature of 80°C for 120 minutes; A2. The temperature is raised to 85°C and kept for 180 minutes, and then the temperature is lowered to 60°C and washed with deionized water for 3 times until neutral; A3. Dehydration is carried out at 120°C and a vacuum of -0.095 MPa for 90 minutes, and after filtration, the epoxy equivalent weight is detected to be 850-900 g / eq, and the product is discharged.

[0008] Preferably, the preparation steps of the epoxy resin B are as follows: B1. Bisphenol A and epichlorohydrin are put into a reaction kettle at a molar ratio of 1:1.15, heated to 90°C under nitrogen protection, and 40% sodium hydroxide solution is slowly added dropwise while controlling the temperature at 95°C for 150 minutes; B2. The reaction is kept for 240 minutes and the pH is maintained above 12, and then toluene solvent is added after the temperature is lowered to 70°C, and washed with water until neutral; B3. Toluene and water are removed at 130°C and a vacuum of -0.098 MPa for 120 minutes, and after the epoxy equivalent weight is detected to be 1700-2000 g / eq, the product is cooled.

[0009] Preferably, the preparation steps of the nitrile rubber modified epoxy resin are as follows: C1. Carboxyl nitrile rubber and epoxy resin A are put into a reactor at a mass ratio of 1:2, heated to 140°C under nitrogen protection, stirred for 60 minutes, and 0.5% triphenylphosphine catalyst is added for further reaction for 180 minutes; C2. The epoxy equivalent weight is detected by sampling, and the reaction is adjusted to be within the range of 750-800 g / eq, and then acetone is added for dilution to a solid content of 70% after the temperature is lowered to 80°C; C3. The gel particles are removed by filtration, and after the acetone is removed at 100°C and a vacuum of -0.092 MPa, the product is discharged.

[0010] Preferably, the stone chip resistant insulating powder coating for automobile battery tray is composed of the following raw materials in parts by weight: epoxy resin A: 16 parts; epoxy resin B: 36 parts; nitrile rubber modified epoxy resin: 6 parts; phenolic resin curing agent: 11 parts; quartz powder: 25 parts; leveling agent: 0.9 parts; pigment (rutile titanium dioxide): 2 parts; curing accelerator (2-methyl imidazole): 0.4 parts; anti-settling agent (fumed silica): 0.7 parts; adhesion promoter (silane coupling agent): 0.4 parts; defoaming agent (benzoin): 0.45 parts; electricity increasing agent (tetraalkyl ammonium salt): 0.5 parts.

[0011] Preferably, the stone chip resistant insulating powder coating for automobile battery tray is composed of the following raw materials in parts by weight: epoxy resin A: 18 parts; epoxy resin B: 38 parts; nitrile rubber modified epoxy resin: 8 parts; phenolic resin curing agent: 12 parts; quartz powder: 30 parts; leveling agent: 1.0 parts; pigment (rutile titanium dioxide): 3 parts; curing accelerator (2-methyl imidazole): 0.6 parts; anti-settling agent (fumed silica): 0.8 parts; adhesion promoter (silane coupling agent): 0.5 parts; defoaming agent (benzoin): 0.45 parts; electricity increasing agent (tetraalkyl ammonium salt): 0.6 parts.

[0012] Preferably, the stone chip resistant insulating powder coating for automobile battery tray is composed of the following raw materials in parts by weight: epoxy resin A: 20 parts; epoxy resin B: 40 parts; nitrile rubber modified epoxy resin: 5 parts; phenolic resin curing agent: 13 parts; quartz powder: 35 parts; leveling agent: 1.2 parts; pigment (rutile titanium dioxide): 1 part; curing accelerator (2-methyl imidazole): 0.3 parts; anti-settling agent (fumed silica): 1.0 parts; adhesion promoter (silane coupling agent): 0.3 parts; defoaming agent (benzoin): 0.45 parts; electricity increasing agent (tetraalkyl ammonium salt): 0.3 parts.

[0013] Preferably, the stone chip resistant insulating powder coating for automobile battery tray is composed of the following raw materials in parts by weight: epoxy resin A: 15 parts; epoxy resin B: 35 parts; nitrile rubber modified epoxy resin: 10 parts; phenolic resin curing agent: 10 parts; quartz powder: 20 parts; leveling agent: 0.8 parts; pigment (rutile titanium dioxide): 5 parts; curing accelerator (2-methyl imidazole): 0.8 parts; anti-settling agent (fumed silica): 0.5 parts; adhesion promoter (silane coupling agent): 0.6 parts; defoaming agent (benzoin): 0.45 parts; electricity increasing agent (tetraalkyl ammonium salt): 0.8 parts.

[0014] The present application also provides a preparation method of the stone chip resistant insulating powder coating for automobile battery tray, comprising the following steps: S1. Put epoxy resin A: 15~20 parts, epoxy resin B: 35~40 parts, butyronitrile rubber modified epoxy resin: 5~10 parts into a premix kettle, jacket temperature 50±2℃, low speed stirring for 10 minutes at 300~400 rpm, add phenolic resin curing agent: 10~13 parts, leveling agent: 0.8~1.2 parts, curing accelerator: 0.3~0.8 parts, adhesion promoter: 0.3~0.6 parts, defoaming agent: 0.3~0.6 parts, electric enhancer: 0.3~0.8 parts and 50% total amount 20~35 parts of quartz powder, the speed is raised to 800~1000 rpm for 15 minutes, finally add the remaining quartz powder, pigment: 1~5 parts, anti-settling agent: 0.5~1 parts, high speed shearing dispersion for 25 minutes at 1200~1500 rpm, until the fineness of the mixture is ≤50 μm; S2. Put the premix into a co-rotating twin screw extruder with a length-diameter ratio of 18:1, control the temperature in four sections, screw speed 400~600 rpm, melt residence time ≤60 seconds, then extrude the melt into 1.0~1.5 mm thick sheets by a double roller press with a roller temperature of 40±2℃ and a roller speed ratio of 1:1.2, and then crush the sheets into flaky particles with a particle size ≤5 mm by liquid nitrogen-50℃ deep cooling crushing; S3. First, put the crushed material into a vortex type cryogenic mill with a grinding chamber temperature of-30℃, continuously control the temperature with liquid nitrogen as the coolant, rotor speed 4500~6000 rpm, grind to D50 particle size 30~40 μm, then separate the coarse powder >80 μm from the fine powder <10 μm by a turbine airflow classifier with a classification wheel frequency of 35~50 Hz, and ensure that the particle size distribution of the finished powder Dv90 ≤65 μm; finally, add fumed silica anti-settling agent: 0.5~1 parts to the qualified powder for surface coating treatment at a mixing machine speed of 200 rpm for 15 minutes, and then discharge and package.

[0015] Preferably, the four-section temperature control parameters of step S2 are: zone 1 80±5℃, zone 2 95±5℃, zone 3 105±5℃, zone 4 100±5℃.

[0016] Compared with the prior art, the beneficial effects of the present application are: The present application simultaneously gives the coating super-high insulation and top anti-stone performance by single coating, completely cancels the secondary construction link; realizes zero VOC emission by using solid powder system; the special toughening resin and gradient curing process make the coating have rigid protection and toughness buffer, the actual measured anti-stone grade reaches 0 level and the insulation strength is more than 35 kV / mm, perfectly adapts to the strict requirements of electric vehicle high-voltage battery system on safety and environmental protection, and solves the technical defects in the traditional scheme. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0018] I. Materials The adhesion enhancer of the present application is a gamma-glycidyl ether oxypropyl trimethoxysilane coupling agent, model number KH-560, and other materials not specified are commercially available; The present application provides a kind of anti-stone impact insulating powder coating of automobile battery tray, it is composed of the following weight parts raw materials: epoxy resin A: 15~20 parts, epoxy resin B: 35~40 parts, nitrile rubber modified epoxy resin: 5~10 parts, phenolic resin curing agent: 10~13 parts, quartz powder: 20~35 parts, leveling agent: 0.8~1.2 parts, pigment: 1~5 parts, curing accelerator: 0.3~0.8 parts, anti-sediment agent: 0.5~1 parts, adhesion enhancer: 0.3~0.6 parts, defoaming agent: 0.3~0.6 parts and power enhancer: 0.3~0.8 parts; Epoxy resin A is epoxy resin with epoxy equivalent of 850-900; epoxy resin B is epoxy resin with epoxy equivalent of 1700-2000; nitrile rubber modified epoxy resin is modified epoxy resin with epoxy equivalent of 750-800; pigment is specifically rutile titanium dioxide; curing accelerator is specifically 2-methylimidazole; anti-sediment agent is specifically fumed silica; adhesion enhancer is specifically silane coupling agent; defoaming agent is specifically benzoin; power enhancer is specifically tetraalkylammonium salt.

[0019] It should be noted that the preparation steps of epoxy resin A are as follows: A1. Bisphenol A and epichlorohydrin are put into a reaction kettle at a molar ratio of 1:1.38, dissolved by heating to 75℃, and then 50% sodium hydroxide solution is added dropwise at a constant temperature of 80℃ for 120 minutes; A2. The temperature is raised to 85℃ and kept for 180 minutes, and then washed with deionized water for 3 times to neutral; A3. Dehydration is carried out at 120℃ under a vacuum of-0.095 MPa for 90 minutes, and the epoxy equivalent is detected to 850-900 g / eq after filtration.

[0020] It should be noted that the preparation steps of epoxy resin B are as follows: B1. Bisphenol A and epichlorohydrin are put into a reaction kettle at a molar ratio of 1:1.15, heated to 90℃ under nitrogen protection, and 40% sodium hydroxide solution is added dropwise slowly while controlling the temperature at 95℃ for 150 minutes; B2. Keep the reaction for 240 minutes and maintain pH>12, after cooling to 70℃, add toluene solvent extraction and water washing to neutral; B3. Remove toluene and moisture at 130℃, -0.098MPa vacuum for 120 minutes, detect the epoxy equivalent to 1700-2000g / eq, then cool.

[0021] It should be noted that the preparation steps of the nitrile rubber modified epoxy resin are as follows: C1. Put the carboxyl nitrile rubber and epoxy resin A into the reactor according to the mass ratio of 1:2, heat to 140℃ under nitrogen protection, stir for 60 minutes, add 0.5% triphenylphosphine catalyst and continue to react for 180 minutes; C2. Take sample to detect the epoxy equivalent, adjust the reaction to the range of 750-800g / eq, cool to 80℃, add acetone to dilute to 70% solid content; C3. Filter to remove gel particles, remove acetone at 100℃, -0.092MPa vacuum, then discharge.

[0022] II. Process: The application also provides a preparation method of the stone impact resistant insulating powder coating for the automobile battery tray, which comprises the following steps: S1. Put epoxy resin A: 15-20 parts, epoxy resin B: 35-40 parts, nitrile rubber modified epoxy resin: 5-10 parts into a premix kettle, jacket temperature 50±2℃, low speed stirring at 300-400rpm for 10 minutes, add phenolic resin curing agent: 10-13 parts, leveling agent: 0.8-1.2 parts, curing accelerator: 0.3-0.8 parts, adhesion enhancer: 0.3-0.6 parts, defoaming agent: 0.3-0.6 parts, electricity enhancer: 0.3-0.8 parts and 50% total amount of 20-35 parts of quartz powder, increase the speed to 800-1000rpm and disperse for 15 minutes, finally add the remaining quartz powder, pigment: 1-5 parts, anti-settling agent: 0.5-1 parts, high speed shear at 1200-1500rpm for 25 minutes, until the fineness of the mixture is ≤50μm; S2. Put the premix into a co-rotating twin screw extruder with a length-diameter ratio of 18:1, control the temperature in four sections, screw speed 400-600rpm, melt residence time ≤60 seconds, then extrude the melt through a double roller press with roller temperature 40±2℃ and roller speed ratio 1:1.2 to press into 1.0-1.5mm thick sheets, crush the sheets into flaky particles with particle size ≤5mm by liquid nitrogen-50℃ deep cooling crushing; S3. First, the broken material is put into the vortex cold mill in the grinding cavity temperature -30℃, with liquid nitrogen as the coolant to control the temperature, the rotor speed is 4500~6000rpm, and the grinding is carried out to D50 particle size 30~40μm, then the coarse powder >80μm and the fine powder <10μm are separated by a turbine airflow classifier with a frequency of 35~50Hz, and the particle size distribution Dv90≤65μm of the finished powder is ensured; finally, fumed silica anti-settling agent: 0.5~1 parts is added to the qualified powder for surface coating treatment at a mixing machine speed of 200rpm for 15 minutes, and then the finished product is discharged and packaged.

[0023] It should be noted that the four-stage temperature control parameters of step S2 are as follows: zone 1 80±5℃, zone 2 95±5℃, zone 3 105±5℃, and zone 4 100±5℃.

[0024] In this embodiment, the anti-stone impact insulation powder coating for automobile battery tray is prepared according to the following process: S1. Raw material premixing and dispersion: Put epoxy resin A: 16 parts, epoxy resin B: 36 parts, nitrile rubber modified epoxy resin: 6 parts into a premixing kettle, with a jacket temperature of 50℃, and stir at 300rpm for 10 minutes; add phenolic resin curing agent: 11 parts, leveling agent: 0.9 parts, 2-methylimidazole: 0.4 parts, silane coupling agent: 0.4 parts, benzoin: 0.45 parts, tetraalkylammonium salt: 0.5 parts, and quartz powder: 12.5 parts, and increase the stirring speed to 800rpm for 15 minutes; finally, add the remaining quartz powder: 12.5 parts, rutile titanium dioxide: 2 parts, fumed silica: 0.7 parts, and disperse at a high speed of 1200rpm for 25 minutes to a fineness of 48μm; S2. Melt extrusion and deep cold crushing: Put the premixed material into a double screw extruder, with four-zone temperature: zone 1 80℃, zone 2 95℃, zone 3 105℃, and zone 4 100℃, and the screw speed is 400rpm; the extrudate is pressed into 1.2mm thick sheets by a double roller press (roller temperature 40℃); and the liquid nitrogen is deep cold (-50℃) crushed to a particle size of 4mm; S3. Cold grinding and classification coating: Put the crushed material into the vortex mill (-30℃), with a rotor speed of 4500rpm, and grind to D50=35μm; separate the coarse / fine powder by a turbine classifier (frequency 35Hz), control Dv90=60μm; add fumed silica: 0.7 parts for coating at 200rpm for 15 minutes, and then discharge; In this example, epoxy resin A is 18 parts, epoxy resin B is 38 parts, nitrile rubber modified epoxy resin is 8 parts, phenolic resin curing agent is 12 parts, quartz powder is 30 parts, leveling agent is 1.0 part, rutile titanium dioxide is 3 parts, 2-methylimidazole is 0.6 part, fumed silica is 0.8 part, silane coupling agent is 0.5 part, and tetraalkylammonium salt is 0.6 part; the S2 screw speed is increased to 500 rpm; and other process parameters are the same as in Example 1. In this example, epoxy resin A is 20 parts, epoxy resin B is 40 parts, nitrile rubber modified epoxy resin is 5 parts, phenolic resin curing agent is 13 parts, quartz powder is 35 parts, leveling agent is 1.2 parts, rutile titanium dioxide is 1 part, 2-methylimidazole is 0.3 part, fumed silica is 1.0 part, silane coupling agent is 0.3 part, and tetraalkylammonium salt is 0.3 part; the S3 grinding temperature is adjusted to -28°C, and the rotor speed is 6000 rpm; and other process parameters are the same as in Example 1. In this example, epoxy resin A is 15 parts, epoxy resin B is 35 parts, nitrile rubber modified epoxy resin is 10 parts, phenolic resin curing agent is 10 parts, quartz powder is 20 parts, leveling agent is 0.8 part, rutile titanium dioxide is 5 parts, 2-methylimidazole is 0.8 part, fumed silica is 0.5 part, silane coupling agent is 0.6 part, and tetraalkylammonium salt is 0.8 part; the S2 liquid nitrogen deep cooling temperature is adjusted to -48°C; and other process parameters are the same as in Example 1. The component values in Examples 1 to 4 are recorded in Table 1: Table 1: Component values in Examples 1 to 4 Raw materials Example 1 Example 2 Example 3 Example 4 Epoxy resin A (EEW 850-900) 16 18 20 15 Epoxy resin B (EEW 1700-2000) 36 38 40 35 Nitrile rubber modified epoxy resin 6 8 5 10 Phenolic resin curing agent 11 12 13 10 Quartz powder 25 30 35 20 Leveling agent 0.9 1.0 1.2 0.8 Rutile titanium dioxide 2 3 1 5 2-methylimidazole 0.4 0.6 0.3 0.8 Fumed silica 0.7 0.8 1.0 0.5 Silane coupling agent (KH-560) 0.4 0.5 0.3 0.6 Tetraalkylammonium salt 0.5 0.6 0.3 0.8 In this comparative example, epoxy resin A is 14 parts, and other components and processes are the same as in Example 1. In this comparative example, epoxy resin B is 41 parts, and other components and processes are the same as in Example 1. In this comparative example, nitrile rubber modified epoxy resin is 4 parts, phenolic resin curing agent is 9 parts, and other components and processes are the same as in Example 1. The component values in Comparative Examples 1 to 4 are recorded in Table 2: Table 2: Component values in Comparative Examples 1 to 4 Raw materials Comparative Example 1 Comparative Example 2 Comparative Example 3 Epoxy resin A (EEW 850-900) 14 16 16 Epoxy resin B (EEW 1700-2000) 36 41 36 Nitrile rubber modified epoxy resin 6 6 4 Phenolic resin curing agent 11 11 9 Quartz powder 25 25 25 Leveling agent 0.9 0.9 0.9 Rutile titanium dioxide 2 2 2 2-methylimidazole 0.4 0.4 0.4 Fumed silica 0.7 0.7 0.7 Silane coupling agent (KH-560) 0.4 0.4 0.4 Tetraalkylammonium salt 0.5 0.5 0.5 III. Performance testing The components in the examples and comparative examples are prepared into performance test samples according to the following process, and the sample preparation process for performance testing includes the following steps: T1. Static spraying plate preparation: using an electrostatic spray gun (output voltage 80~90kV, powder gas pressure 0.5~0.7MPa) to uniformly spray the powder to the pretreated (degreasing, phosphating) steel plate (size 150×70×1mm), the film thickness is controlled to 200±20μm; T2. Gradient curing molding: first, the coating is apparent to flow in the infrared preheating section (80℃±2℃, time 3 minutes); then, the gradient curing is performed in the curing oven: First stage: 100℃ / 10 minutes (eliminate internal stress); Second stage: 180℃±2℃ / 15 minutes (complete crosslinking); Third stage: forced air cooling to below 50℃, to obtain the test sample plate; The performance tests are carried out according to the following standards, see Table 3: Table 3 Performance test standard table Item Requirement Standard Dielectric strength ≥30 KV / mm GB / T 1408.2 Insulating materials - Determination of electrical strength - Part 2: Additional requirements for tests with DC voltage Shear strength ≥7 MPa GB / T 7124 Determination of tensile shear strength of adhesives (rigid material to rigid material) Tensile strength ≥7 MPa GB / T 5210 Paints and varnishes - Pull-over test for adhesion Impact resistance at 25℃ 50 kg·cm, 4 times magnifying glass, no coating cracking, peeling, paint exposure, cracking and other defects, and after testing, it meets the insulation withstand voltage requirements GB / T 1732 Impact resistance of paint films Stone chip resistance 0-1 level, no breakdown of the substrate GB / T 9286-2015‌ The performance parameters of the samples of Examples 1-4 are recorded, see Table 4: Table 4 Performance parameter table of samples of Examples 1-4 Test item Example 1 Example 2 Example 3 Example 4 Insulation withstand voltage (kV / mm) 36 35 34 33 Volume resistivity (Ω·cm) 3.2 x 10 5 ]] 2.8 x 10 5 ]] 1.9 x 10 5 ]] 1.5 x 10 5 ]]> Stone chip resistance level 0 level 0 level 1 level 1 level Impact resistance at 25℃ (kg·cm) 55 52 50 51 Shear strength (MPa) 8.2 7.8 7.1 7.0 The performance parameters of the samples of Comparative Examples 1-3 are recorded, see Table 5: Table 5 Performance parameter table of samples of Comparative Examples 1-3 Test item Comparative Example 1 Comparative Example 2 Comparative Example 3 Insulation withstand voltage (kV / mm) 28 26 25 Volume resistivity (Ω·cm) 8.7×10¹³ 5.2×10¹³ 3.8×10¹³ Stone chip resistance level 3 level 4 level 5 level Impact resistance at 25℃ (kg·cm) 42 38 35 Shear strength (MPa) 5.3 4.7 4.1 IV. Analysis conclusion: The epoxy resin B≥35 parts in the examples provides a long molecular chain dense structure, while the insulating voltage of Comparative Example 1 is reduced to 28kV / mm (<30kV / mm) due to the insufficient epoxy resin A (14 parts), and the insulating voltage of Comparative Example 2 is only 26kV / mm; the butyl nitrile rubber modified epoxy resin 5-10 parts forms an island structure, while the anti-stone impact grade of Comparative Example 3 is deteriorated to 5 levels (>1 level) due to the insufficient toughening resin (4 parts); the phenolic curing agent 10-13 parts avoids undercuring, while the shear of Comparative Example 3 is 4.1MPa; in summary, the rationality of the component interval setting of the anti-stone impact insulating powder coating for the automobile battery tray of the application is known; And because of the high toughness resin ratio (A:B:toughening=16:36:6) in Example 1, the anti-stone impact reaches 0 level; the medium quartz powder (25 parts) takes into account the insulation (36kV / mm) and the adhesion (8.2MPa); the precise accelerator (0.4 parts 2-methylimidazole) ensures complete curing without bubbles at 180℃, therefore, Example 1 is the best embodiment of the application.

[0025] To sum up, the present application synchronously gives the coating with super-high insulation and top anti-stone performance by single coating, completely cancels the secondary construction link; realizes zero VOC emission by adopting solid powder system; the special toughening resin and gradient curing process make the coating have rigid protection and toughness buffer, the actually measured anti-stone grade reaches 0 level and the insulation strength is more than 35kV / mm, perfectly adapts the strict requirements of the high-voltage battery system of electric vehicles on safety and environmental protection, and solves the technical defects in the traditional scheme.

[0026] In the description of the present specification, the description referring to the terms "one embodiment", "an example", "a specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0027] The preferred embodiments of the application disclosed above are only used to help explain the present application. The preferred embodiments do not describe all the details and limit the present application to the specific embodiments described. Obviously, according to the content of the present specification, many modifications and changes can be made. The present specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present application, so that those skilled in the art can well understand and utilize the present application. The present application is limited only by the claims and their full scope and equivalents.

Claims

1. A stone-impact resistant insulating powder coating for a car battery tray, characterized in that: The invention is composed of the following raw materials in parts by weight: 15-20 parts of epoxy resin A, 35-40 parts of epoxy resin B, 5-10 parts of nitrile rubber modified epoxy resin, 10-13 parts of phenolic resin curing agent, 20-35 parts of quartz powder, 0.8-1.2 parts of leveling agent, 1-5 parts of pigment, 0.3-0.8 parts of curing accelerator, 0.5-1 parts of anti-settling agent, 0.3-0.6 parts of adhesion promoter, 0.3-0.6 parts of defoaming agent and 0.3-0.8 parts of charge enhancer. The epoxy resin A is an epoxy resin with an epoxy equivalent of 850-900; the epoxy resin B is an epoxy resin with an epoxy equivalent of 1700-2000; the nitrile rubber modified epoxy resin is a modified epoxy resin with an epoxy equivalent of 750-800; the pigment is specifically rutile titanium dioxide; the curing accelerator is specifically 2-methylimidazole; the anti-settling agent is specifically fumed silica; the adhesion promoter is specifically a silane coupling agent; the defoaming agent is specifically benzoin; and the charge enhancer is specifically a tetraalkylammonium salt.

2. The anti-stone chip insulating powder coating for an automobile battery tray according to claim 1, characterized in that: The preparation steps of the epoxy resin A are: A1. Bisphenol A and epichlorohydrin were added to a reactor at a molar ratio of 1:1.38 and heated to 75°C to dissolve. Then, 50% sodium hydroxide solution was added dropwise at a constant temperature of 80°C for 120 minutes. A2. Heat to 85°C and incubate for 180 minutes, then cool to 60°C and wash three times with deionized water until neutral. A3. Dehydrate at 120°C and -0.095 MPa vacuum for 90 minutes. After filtration, test the epoxy equivalent to 850-900 g / eq.

3. The anti-stone chip insulating powder coating for an automobile battery tray according to claim 2, characterized in that: The preparation steps of the epoxy resin B are: B1. Bisphenol A and epichlorohydrin were added to the reactor in a molar ratio of 1:1.

15. The temperature was raised to 90°C under nitrogen protection. 40% sodium hydroxide solution was slowly added dropwise while maintaining the temperature at 95°C for 150 minutes. B2. Incubate the reaction for 240 minutes and maintain pH>12, cool to 70°C, extract with toluene solvent and wash with water until neutral; B3. Remove toluene and water at 130°C and -0.098 MPa vacuum for 120 minutes, detect the epoxy equivalent to 1700-2000 g / eq, and then cool.

4. The anti-stone chip insulating powder coating for an automobile battery tray according to claim 3, characterized in that: The preparation steps of the nitrile rubber modified epoxy resin are as follows: C1. Carboxylated nitrile rubber and epoxy resin A were placed in a reactor at a mass ratio of 1:

2. The temperature was raised to 140°C under nitrogen and stirred for 60 minutes. 0.5% triphenylphosphine catalyst was added and the reaction was continued for 180 minutes. C2. Take a sample to test the epoxy equivalent, adjust the reaction to 750-800g / eq, cool to 80°C, add acetone and dilute to 70% solid content; C3. Filter to remove gel particles, remove acetone at 100°C and -0.092 MPa vacuum, and then discharge the material.

5. The anti-stone chip insulating powder coating for automobile battery tray according to claim 4, characterized in that: The invention is composed of the following raw materials in parts by weight: epoxy resin A: 16 parts; epoxy resin B: 36 parts; nitrile rubber modified epoxy resin: 6 parts; phenolic resin curing agent: 11 parts; quartz powder: 25 parts; leveling agent: 0.9 parts; pigment: 2 parts; curing accelerator: 0.4 parts; anti-settling agent: 0.7 parts; adhesion promoter: 0.4 parts; defoaming agent: 0.45 parts; and charge enhancer: 0.5 parts.

6. The anti-stone chip insulating powder coating for automobile battery tray according to claim 5, characterized in that: The invention is composed of the following raw materials in parts by weight: epoxy resin A: 18 parts; epoxy resin B: 38 parts; nitrile rubber modified epoxy resin: 8 parts; phenolic resin curing agent: 12 parts; quartz powder: 30 parts; leveling agent: 1.0 parts; pigment: 3 parts; curing accelerator: 0.6 parts; anti-settling agent: 0.8 parts; adhesion promoter: 0.5 parts; defoaming agent: 0.45 parts; and charge enhancer: 0.6 parts.

7. The anti-stone chip insulating powder coating for an automobile battery tray according to claim 6, characterized in that: The invention is composed of the following raw materials in parts by weight: epoxy resin A: 20 parts; epoxy resin B: 40 parts; nitrile rubber modified epoxy resin: 5 parts; phenolic resin curing agent: 13 parts; quartz powder: 35 parts; leveling agent: 1.2 parts; pigment: 1 part; curing accelerator: 0.3 parts; anti-settling agent: 1.0 parts; adhesion promoter: 0.3 parts; defoaming agent: 0.45 parts; and charge enhancer: 0.3 parts.

8. The anti-stone chip insulating powder coating for automobile battery tray according to claim 7, characterized in that: The invention is composed of the following raw materials in parts by weight: epoxy resin A: 15 parts; epoxy resin B: 35 parts; nitrile rubber modified epoxy resin: 10 parts; phenolic resin curing agent: 10 parts; quartz powder: 20 parts; leveling agent: 0.8 parts; pigment: 5 parts; curing accelerator: 0.8 parts; anti-settling agent: 0.5 parts; adhesion promoter: 0.6 parts; defoaming agent: 0.45 parts; and charge enhancer: 0.8 parts.

9. The method for preparing the stone chip resistant insulating powder coating for an automobile battery tray according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Epoxy resin A: 15-20 parts, epoxy resin B: 35-40 parts, nitrile rubber modified epoxy resin: 5-10 parts were added to a stirring pot, phenolic resin curing agent: 10-13 parts, leveling agent: 0.8-1.2 parts, curing accelerator: 0.3-0.8 parts, adhesion promoter: 0.3-0.6 parts, defoaming agent: 0.3-0.6 parts, charge enhancer: 0.3-0.8 parts and 20-35 parts by mass of quartz powder, pigment: 1-5 parts, stirred at a low speed of 300-400 rpm for 10 minutes, then the speed was increased to 800-1000 rpm and dispersed for 3 minutes; S2. The premix was fed into a co-rotating twin-screw extruder with an aspect ratio of 18:

1. The temperature was controlled in four stages, the screw speed was 400-600 rpm, and the melt residence time was ≤60 seconds. The molten material was then extruded into a 1.0-1.5 mm thick sheet on a twin-roll tablet press with a roller temperature of 15±2°C and a roller speed ratio of 1:1.

2. The sheet was then crushed into flake particles with a particle size of ≤5 mm using a coarse crusher. S3. First, put the crushed material into the ACM air classifying mill with a grinding chamber temperature of 5°C, and add fumed silica loosening agent. The main mill speed is 3000~3500rpm, and the auxiliary mill speed is 2000~2500rpm. Grind to a D50 particle size of 40~50μm, D10>12um, D90<95um. After completion, discharge and package.

10. The method for preparing the stone chip resistant insulating powder coating for an automobile battery tray according to claim 9, characterized in that: The four-stage temperature control parameters of step S2 are: zone 1 30±5°C, zone 2 75±5°C, zone 3 105±5°C, zone 4 100±5°C.