Precoated coil epoxy-based back coating

Abstract

The application discloses a high-processability epoxy back coating which can be used in the field of pre-coated coil; the application aims to provide a high solid content, high processability, low VOC, high mechanical property pre-coated coil epoxy back coating; it comprises the following components by mass fraction: modified epoxy resin A is 15-20 parts, modified epoxy resin B is 50-65 parts, dispersing agent is 0.2-1 part, filler is 5-15 parts, pigment is 0.1-10 parts, core-shell nano material is 0.4-6 parts, solvent is 1-5 parts, anti-sedimentation thixotropic agent is 0.5-1 part, adhesion promoter is 0.5-2.0 parts, curing agent is 6-10 parts, and the sum of the weight parts of the components is 100 parts; after paint preparation, the non-volatile matter content is greater than or equal to 80%, the viscosity is 80-125 s (coating-4 cups, 25 DEG C), the VOC is less than 300 g / L, and the sedimentation grade is greater than or equal to 8.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of paint preparation, in particular to a high-processability epoxy back paint for pre-coated coil. BACKGROUND

[0002] Pre-coated coil back paint is mainly used for protection on the back of the coil. Common coil back paint mainly includes epoxy resin, polyester resin and epoxy-polyester resin system. Among them, epoxy back paint has high hardness, excellent adhesion and good MEK wiping resistance, but poor flexibility; while polyester back paint has good flexibility, but relatively poor MEK wiping resistance and adhesion; and the epoxy-polyester resin system has poor T-bending performance, poor flexibility, batch fluctuation, obvious storage stratification and other problems after compounding. Therefore, the prior art often uses epoxy modified polyester resin to improve the above problems. For example, the patent CN 113604137 B uses epoxy resin to modify polyester resin and compounding with branched polyester resin to develop a high-coated coil back paint with high hardness, excellent adhesion and good pressure resistance. However, the solid content of the prepared paint is still 65%, and the VOC is higher than 420g / L. SUMMARY

[0003] In order to solve the above technical problems such as poor flexibility, poor wear resistance and low processability, the present application provides a high-solid, high-processability, low-VOC and high-mechanical-property pre-coated coil epoxy back paint.

[0004] The present application discloses a pre-coated coil epoxy back paint, which comprises the following components by mass fraction: modified epoxy resin A 15-20 parts, modified epoxy resin B 50-65 parts, dispersing agent 0.2-1 part, filler 5-15 parts, pigment 0.1-10 parts, core-shell nano material 0.4-6 parts, solvent 1-5 parts, anti-settling thixotropic agent 0.5-1 part, adhesion promoter 0.5-2.0 parts, and curing agent 6-10 parts, wherein the sum of the weight fractions of the components is 100 parts.

[0005] The preparation of the modified epoxy resin A is as follows: first, 10-20 parts of toluene diisocyanate and 5-10 parts of dimethylbenzene are put into a reaction kettle, a mixed liquid composed of 5 parts of dimethylbenzene and 1-7 parts of 1,4-butanediol is slowly added dropwise, the dropping is completed within 1-2 hours, the reaction temperature is 35±5℃, after the NOC content is determined to be unchanged, the temperature is raised to 40℃±5℃, a mixed liquid composed of 10-12 parts of dimethylbenzene and 50-60 parts of liquid epoxy resin is added dropwise, after the isocyanate group is completely reacted, 0.5-1 parts of alkyl glycidyl ether is used for dilution to obtain the modified epoxy resin A.

[0006] The modified epoxy resin B is prepared as follows: 68-79 parts of solid epoxy resin, 15.8-19.3 parts of xylene and 0.13-0.16 parts of zinc oxide are added to a reaction kettle, heated to 110±5°C, 1.7-10.1 parts of acrylic acid monomer are added dropwise within 30 minutes, the mixture is kept warm until the acid value is below 5 mgKOH / g, 2.8-3.3 parts of xylene, 0.33-0.37 parts of BPO and 0.39-2.2 parts of di-tertiary carbon isocyanurate are added dropwise within 1.5-2 hours, the mixture is kept warm for 1.5 hours, 0.2 parts of xylene and 0.2 parts of BPO are added, the mixture is kept warm for 1.5 hours, and then diluted with 1-2 parts of a reactive diluent, alkyl glycidyl ether, to obtain the modified epoxy resin B;

[0007] Wherein, the core-shell nanomaterials are prepared by the following methods:

[0008] Step 1: Ultrasonic dispersion of 20-30 parts of 3-methyl-2-butenamine, 1-5 parts of hydroxylated nano-silica, 5-10 parts of anhydrous ethanol, and 55-74 parts of deionized water was performed. The mixture was magnetically stirred in a water bath at 25°C ± 2°C for 2-5 hours. After filtering and repeated washing, the mixture was dried using a freeze dryer to obtain amine-coated silica, which was referred to as amine@SiO2.

[0009] Step 2: Add 2-5 parts of amine@SiO2, 70-80 parts of deionized water and 0.01-0.05 parts of sodium lauryl sulfate into a round-bottom flask, stir at high speed until uniformly dispersed, and then add a mixture consisting of 5-10 parts of butyl acrylate, 1-2 parts of versatate epoxy acrylate and 0.05-1 part of BPO. After the addition is completed within 0.5-1 hour, continue to keep warm for 6-8 hours, and then add emulsified water consisting of 0.01-0.02 parts of sodium lauryl sulfate and 10-20 parts of water. After the monomer smell disappears, filter, wash, and freeze-dry to obtain a toughened core-shell nanomaterial.

[0010] The above components are stirred, mixed and ground to obtain a pre-coil coating with a viscosity of 80-125s (co-4 cup, 25°C) and a solid content of ≥80%; the total weight of each component is 100 parts.

[0011] Preferably, the dispersant is one or more of BYK182, BYK183, and BYK185;

[0012] Preferably, the pigment is one or more of titanium dioxide, iron oxide red, iron oxide yellow, phthalocyanine green, phthalocyanine blue, and carbon black;

[0013] Preferably, the filler is one or more of barium sulfate, talc powder, and calcite powder;

[0014] As a preference, the anti-settling thixotropic agent is one or more of bentonite powder, fumed silica, polyamide wax;

[0015] As a preference, the adhesion promoter FBS001;

[0016] As a preference, the curing agent is one or both of fully methylated melamine resin, partially methylated melamine resin.

[0017] As a preference, the liquid epoxy resin is one or both of EPOXYLINE® 618, EPOXYLINE® 6101, or EPOXYLINE® 634;

[0018] As a preference, the alkyl glycidyl ether is one or more of C4-C12;

[0019] As a preference, the solid epoxy resin is one or more of EPOXYLINE® 601, EPOXYLINE® 604, EPOXYLINE® 607, and EPOXYLINE® 609;

[0020] As a preference, the alkyl glycidyl ether is one or more of C6-C12;

[0021] As a preference, the hydroxylated silica has a particle size of 100-200 nm.

[0022] The present application uses toluene isocyanate and 1,4-butanediol to chain-extend small molecule epoxy resin, and improve the flexibility of the resin. The present application uses double tertiary carbon isocyanurate glycerol ester to graft-modify solid epoxy resin. The special structure of the functional monomer, i.e. the cyclic structure and long branched chain structure, can not only improve the wettability of the solid epoxy resin and pigments, reduce the amount of solvent, but also improve the solvent resistance and interlayer peeling strength of the resin product. At the same time, the molecular chain of the epoxy resin after grafting the monomer has a certain spatial position and provides part of the hydroxyl functional groups. The modified epoxy resin A and the modified epoxy resin B form a gradient difference in the drying and curing rate, but finally ensure sufficient crosslinking degree. The present application uses 3-methyl-2-butene amine to modify silica to prepare core-shell particles, and uses butyl acrylate and tertiary carbon epoxy acrylate. The core-shell particles produce cavitation and shear yield to improve the bending resistance and impact resistance of the paint film. The tertiary carbon epoxy acrylate has excellent wettability and adhesion, improves the compatibility and dispersion of the nanomaterials to the resin and pigments and fillers, and improves the storage stability. The present application uses active diluent to adjust the system, and improves the compatibility between the resins and the storage stability of the paint. When the paint is cured, with the evaporation of the solvent and the reaction of the active diluent and the curing agent, the modified epoxy resin A becomes the lower layer of the paint film, and the modified epoxy resin B becomes the upper layer of the paint film. The modified epoxy resin A forms a relatively flexible lower layer, and the modified epoxy resin B forms a high-hardness and high-wear-resistance upper layer. Through self-layering, the upper and lower layers of the paint are not in contact with air, which promotes the interlayer adhesion. When external force friction or impact occurs, the high-wear-resistance upper layer further improves the wear resistance and high processability of the coating, and avoids the problem of mechanical property decline caused by adding too many nanoparticles. In addition, the adhesion promoter is added during the preparation of the paint to improve the adhesion of the paint film.

[0023] 1. The present application graft-modifies solid epoxy resin by double tertiary carbon isocyanurate glycerol ester, and improves the crosslinking degree of the paint film through the special structure of the modified monomer. The paint film prepared by the present application has high hardness, high wear resistance and high solvent resistance, etc. The hardness of the paint film prepared by the present application is ≥3H, and the wear resistance (1000g / 1000r) is ≤0.1g.

[0024] 2. The present application toughens and modifies liquid epoxy resin, and uses modified silica core-shell particles to improve the brittleness of the small molecule liquid epoxy resin. Through the difference in curing and drying, the present application forms a bottom layer for the paint film. The T-bending of the paint film is ≤1T, and the reverse impact is ≥90kg·cm.

[0025] 3. The modified liquid epoxy resin and the modified solid epoxy resin are used in proportion, and are matched with active diluent. The non-volatile content of the paint prepared by the present application is ≥80%, the viscosity is 80-125s (4-cup, 25℃), the VOC is <300g / L, and the sedimentation grade is ≥8 levels (50±2℃ / 30d). DETAILED DESCRIPTION

[0026] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with preferred embodiments.

[0027] Example 1:

[0028] The present invention discloses an epoxy resin backside paint for pre-coated coils, which is prepared by the following method:

[0029] Modified epoxy resin A:

[0030] First, 13.5 parts of toluene diisocyanate and 5 parts of xylene were added into the reactor, and a mixture of 5 parts of xylene and 5.5 parts of 1,4-butanediol was slowly added dropwise within 1 hour. The reaction temperature was 35°C. After the NOC content was determined to be unchanged, the temperature was raised to 40°C, and a mixture of 10 parts of xylene and 60 parts of 618 epoxy resin was added dropwise. After the isocyanate group reacted completely, it was diluted with 1 part of 1,4-butanediol glycidyl ether to obtain a modified epoxy resin.

[0031] Modified epoxy resin B:

[0032] 68.08 parts of 601 epoxy resin, 15.09 parts of xylene and 0.13 parts of zinc oxide were put into a reactor. After heating to 110°C, 9.7 parts of acrylic acid monomer were added dropwise and the mixture was completed within 30 minutes. After keeping the temperature until the acid value was below 5 mgKOH / g, a mixture of 3.15 parts of xylene, 0.35 parts of initiator and 2.1 parts of di-tert-isocyanuric acid glycerol was added dropwise and the mixture was completed within 1.5 hours. After keeping the temperature for 1.5 hours, 0.2 parts of xylene and 0.2 parts of BPO were added. After keeping the temperature for 1.5 hours, the mixture was diluted with 1 part of deoxynyl glycidyl ether to obtain modified epoxy resin B.

[0033] Core-shell nanomaterials:

[0034] Step 1: Ultrasonic dispersion of 25 parts of 3-methyl-2-butenamine, 3 parts of hydroxylated nano-silica, 8 parts of anhydrous ethanol and 64 parts of deionized water was performed, followed by magnetic stirring at 25°C in a water bath for 3 hours. After filtering and repeated washing, the mixture was dried using a freeze dryer to obtain amine-coated silica, referred to as amine@SiO2.

[0035] Step 2: Add 2.6 parts of amine@SiO2, 72.4 parts of deionized water and 0.03 parts of sodium lauryl sulfate into a round-bottom flask, stir at high speed until uniformly dispersed, and then add a mixture consisting of 8 parts of butyl acrylate, 2 parts of versatate epoxy acrylate and 0.06 parts of BPO. After the addition is completed within 0.5 hours, continue to keep warm for 6 hours and then add emulsified water consisting of 0.01 parts of sodium lauryl sulfate and 15 parts of water. After the monomer smell disappears, filter, wash, and freeze-dry to obtain a toughened core-shell nanomaterial.

[0036] The epoxy resin back paint for pre-coated coils is composed of the following components in parts by mass: 15 parts of modified epoxy resin A, 55 parts of epoxy resin B, 0.3 parts of BYK183, 5 parts of talc, 8 parts of titanium dioxide, 5 parts of core-shell nanomaterials, 4.6 parts of xylene, 0.5 parts of anti-settling thixotropic agent, 0.6 parts of adhesion promoter, and 6 parts of curing agent.

[0037] Example 2:

[0038] The present invention discloses an epoxy resin backside paint for pre-coated coils, which is prepared by the following method:

[0039] Modified epoxy resin A:

[0040] First, 15 parts of toluene diisocyanate and 8 parts of xylene were added into the reactor, and a mixture of 5 parts of xylene and 6.5 parts of 1,4-butanediol was slowly added dropwise within 2 hours. The reaction temperature was 40°C. After the NOC content was determined to be unchanged, the temperature was raised to 45°C, and a mixture of 10 parts of xylene and 55 parts of 6101 epoxy resin was added dropwise. After the isocyanate group reacted completely, it was diluted with 0.5 parts of octyl glycidyl ether to obtain a modified epoxy resin.

[0041] Modified epoxy resin B

[0042] 68.08 parts of 601 epoxy resin, 15.69 parts of xylene and 0.13 parts of zinc oxide were put into a reactor. After heating to 115°C, 10.1 parts of acrylic acid monomer were added dropwise and the mixture was completed within 30 minutes. After keeping the temperature until the acid value was below 5 mgKOH / g, a mixture of 3.15 parts of xylene, 0.35 parts of initiator and 1.1 parts of di-tert-isocyanuric acid glycerol was added dropwise and the mixture was completed within 2 hours. After keeping the temperature for 1.5 hours, 0.2 parts of xylene and 0.2 parts of BPO were added. After keeping the temperature for 1.5 hours, the mixture was diluted with 1 part of octyl glycidyl ether to obtain modified epoxy resin B.

[0043] Core-shell nanomaterials:

[0044] Step 1: Ultrasonic dispersion of 25 parts of 3-methyl-2-butenamine, 3 parts of hydroxylated nano-silica, 8 parts of anhydrous ethanol and 64 parts of deionized water was performed, followed by magnetic stirring at 27°C in a water bath for 3 hours. After filtering and repeated washing, the mixture was dried using a freeze dryer to obtain amine-coated silica, referred to as amine@SiO2.

[0045] Step 2: Add 2.6 parts of amine@SiO2, 72.4 parts of deionized water and 0.03 parts of sodium lauryl sulfate into a round-bottom flask, stir at high speed until uniformly dispersed, and then add a mixture consisting of 8 parts of butyl acrylate, 1.9 parts of versatate epoxy acrylate and 0.06 parts of BPO. After the addition is completed within 1 hour, continue to keep warm for 8 hours and then add emulsified water consisting of 0.01 parts of sodium lauryl sulfate and 15 parts of water. After the monomer smell disappears, filter, wash, and freeze-dry to obtain a toughened core-shell nanomaterial.

[0046] The epoxy resin back paint for pre-coated coils is composed of the following components in parts by mass: 15 parts of modified epoxy resin A, 55 parts of epoxy resin B, 0.3 parts of BYK183, 5 parts of talc, 8 parts of titanium dioxide, 5 parts of core-shell nanomaterials, 4.6 parts of xylene, 0.5 parts of anti-settling thixotropic agent, 0.6 parts of adhesion promoter, and 6 parts of curing agent.

[0047] Example 3:

[0048] The present invention discloses an epoxy resin backside paint for pre-coated coils, which is prepared by the following method:

[0049] Modified epoxy resin A:

[0050] First, 10 parts of toluene diisocyanate and 5 parts of xylene were added into the reactor, and a mixture of 5 parts of xylene and 6 parts of 1,4-butanediol was slowly added dropwise. The mixture was completed within 1.5 hours. The reaction temperature was 38°C. After the NOC content was determined to be unchanged, the temperature was raised to 42°C, and a mixture of 12 parts of xylene and 60 parts of 634 epoxy resin was added dropwise. After the isocyanate group reacted completely, it was diluted with 1 part of 1,4-butanediol glycidyl ether to obtain a modified epoxy resin.

[0051] Modified epoxy resin B:

[0052] 76.20 parts of 609 epoxy resin, 15.43 parts of xylene and 0.16 parts of zinc oxide were put into a reactor. After heating to 112°C, 1.72 parts of acrylic acid monomer were added dropwise and the mixture was completed within 30 minutes. After keeping warm until the acid value was below 5 mgKOH / g, a mixture of 3.52 parts of xylene, 0.38 parts of initiator and 0.39 parts of di-tert-isocyanuric acid glycerol was added dropwise and the mixture was completed within 1.7 hours. After keeping warm for 1.5 hours, 0.1 parts of xylene and 0.1 parts of BPO were added. After keeping warm for 1.5 hours, the mixture was diluted with 2 parts of deoxynyl glycidyl ether to obtain modified epoxy resin B.

[0053] Core-shell nanomaterials:

[0054] Step 1: Ultrasonic dispersion of 20 parts of 3-methyl-2-butenamine, 3 parts of hydroxylated nano-silica, 8 parts of anhydrous ethanol and 69 parts of deionized water was performed, followed by magnetic stirring at 26°C in a water bath for 5 hours. After filtering and repeated washing, the mixture was dried using a freeze dryer to obtain amine-coated silica, referred to as amine@SiO2.

[0055] Step 2: Add 5 parts of amine@SiO2, 72 parts of deionized water and 0.02 parts of sodium lauryl sulfate into a round-bottom flask, stir at high speed until uniformly dispersed, and then add a mixture consisting of 10 parts of butyl acrylate, 2 parts of versatate epoxy acrylate and 0.06 parts of BPO. After the addition is completed within 0.5-1 hour, continue to keep warm for 7 hours and then add emulsified water consisting of 0.02 parts of sodium lauryl sulfate and 10.9 parts of water. After the monomer smell disappears, filter, wash, and freeze-dry to obtain a toughened core-shell nanomaterial.

[0056] The epoxy resin back paint for pre-coated coiled material is composed of the following components in parts by mass: 16 parts of modified epoxy resin A, 58 parts of modified epoxy resin B, 0.3 parts of BYK185, 6 parts of precipitated barium sulfate, 3 parts of red iron oxide, 5 parts of core-shell nanomaterials, 3.6 parts of xylene, 0.5 parts of anti-settling thixotropic agent, 0.6 parts of adhesion promoter, and 7 parts of curing agent.

[0057] Example 4

[0058] The present invention discloses an epoxy resin backside paint for pre-coated coils, which is prepared by the following method:

[0059] Modified epoxy resin A:

[0060] First, 20 parts of toluene diisocyanate and 5 parts of xylene are put into a reaction kettle, a mixture liquid composed of 5 parts of xylene and 7 parts of 1,4-butanediol is slowly added dropwise, and the reaction temperature is 36℃. The NOC content is constant, and then the temperature is raised to 43℃. A mixture liquid composed of 10 parts of xylene and 53 parts of 634 epoxy resin is added dropwise until the isocyanate group is completely reacted. Then, 1 part of 1,4-butanediol glycidyl ether is used for dilution to obtain modified epoxy resin A.

[0061] Modified epoxy resin B:

[0062] 76.20 parts of 609 epoxy resin, 15.43 parts of xylene and 0.16 parts of zinc oxide are put into a reaction kettle, and then the temperature is raised to 112℃. 1.72 parts of acrylic monomer are added dropwise within 30 minutes. After the acid value is less than 5 mgKOH / g, a mixture liquid composed of 3.52 parts of xylene, 0.38 parts of BPO and 0.39 parts of glycerol isocyanurate is added dropwise within 1.9 hours. After 1.5 hours of preservation, 0.1 parts of xylene and 0.1 parts of initiator are added. After 1.5 hours of preservation, 2 parts of kauri glycidyl ether is used for dilution to obtain modified epoxy resin B.

[0063] Core-shell nanomaterial:

[0064] Step 1: 20 parts of 3-methyl-2-butene amine, 3 parts of hydroxylated nano silica, 8 parts of anhydrous ethanol and 69 parts of deionized water are ultrasonically dispersed, then magnetically stirred at 28℃ in a water bath for 4 hours. After repeated washing and filtration, the amine-coated silica is dried by a freeze dryer and is denoted as amine@SiO2.

[0065] Step 2: 5 parts of amine@SiO2, 72 parts of deionized water and 0.02 parts of sodium dodecyl sulfate are added to a round-bottom flask, and then stirred at high speed until uniformly dispersed. A mixture liquid composed of 10 parts of butyl acrylate, 2 parts of tertiary carbonic acid epoxy acrylate and 0.06 parts of BPO is added dropwise within 0.78 hours. After 7.5 hours of continuous preservation, emulsified water composed of 0.02 parts of sodium dodecyl sulfate and 10.9 parts of water is added. After the monomer smell disappears, the mixture is filtered, washed, and freeze-dried to obtain a toughened core-shell nanomaterial.

[0066] The pre-coated coil epoxy resin back paint is composed of the following components by mass parts: modified epoxy resin 17.5 parts, modified epoxy resin B 58 parts, BYK185 0.3 parts, precipitated barium sulfate 5.1 parts, red iron oxide 3 parts, core-shell nanomaterial 3.5 parts, xylene 4.5 parts, anti-settling thixotropic agent 0.5 parts, adhesion promoter 0.6 parts, curing agent 7 parts.

[0067] Test performance:

[0068]

[0069]

[0070] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any simplified modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A pre-coated coil epoxy resin back paint, characterized by: The invention comprises the following components in parts by mass: 15-20 parts of modified epoxy resin A, 50-65 parts of modified epoxy resin B, 0.2-1 parts of dispersant, 5-15 parts of filler, 0.1-10 parts of pigment, 0.4-6 parts of core-shell nanomaterial, 1-5 parts of solvent, 0.5-1 parts of anti-settling thixotropic agent, 0.5-2.0 parts of adhesion promoter, and 6-10 parts of curing agent, with the total weight of each component being 100 parts. Preparation of the modified epoxy resin A: First, 10-20 parts of toluene diisocyanate and 5-10 parts of xylene are added to a reaction kettle, and a mixture consisting of 5 parts of xylene and 1-7 parts of 1,4-butanediol is slowly added dropwise within 1-2 hours. The reaction temperature is 35±5°C. After the NCO content is determined to be unchanged, the temperature is raised to 40°C±5°C, and a mixture consisting of 10-12 parts of xylene and 50-60 parts of liquid epoxy resin is added dropwise. After the isocyanate groups react completely, the mixture is diluted with 0.5-1 part of alkyl glycidyl ether to obtain the modified epoxy resin A. The modified epoxy resin B is prepared as follows: 68-79 parts of solid epoxy resin, 15.8-19.3 parts of xylene and 0.13-0.16 parts of zinc oxide are added to a reaction kettle, heated to 110±5°C, 1.7-10.1 parts of acrylic acid monomer are added dropwise within 30 minutes, the mixture is kept warm until the acid value is below 5 mgKOH / g, 2.8-3.3 parts of xylene, 0.33-0.37 parts of BPO and 0.39-2.2 parts of di-tertiary carbon isocyanurate are added dropwise within 1.5-2 hours, the mixture is kept warm for 1.5 hours, 0.2 parts of xylene and 0.2 parts of BPO are added, the mixture is kept warm for 1.5 hours, and then diluted with 1-2 parts of a reactive diluent, alkyl glycidyl ether, to obtain the modified epoxy resin B; Wherein, the core-shell nanomaterial is prepared by the following method: Step 1: Ultrasonic dispersion of 20-30 parts of 3-methyl-2-butenamine, 1-5 parts of hydroxylated nano-silica, 5-10 parts of anhydrous ethanol, and 55-74 parts of deionized water was performed. The mixture was magnetically stirred in a water bath at 25°C ± 2°C for 2-5 hours. After filtering and repeated washing, the mixture was dried using a freeze dryer to obtain amine-coated silica, which was referred to as amine@SiO2. Step 2: Add 2-5 parts of amine@SiO2, 70-80 parts of deionized water and 0.01-0.05 parts of sodium lauryl sulfate into a round-bottom flask, stir at high speed until uniformly dispersed, then dropwise add a mixture of 5-10 parts of butyl acrylate, 1-2 parts of versatate epoxy acrylate and 0.05-1 part of BPO. After the dropwise addition is completed within 0.5-1 hour, continue to keep warm for 6-8 hours, then add emulsified water consisting of 0.01-0.02 parts of sodium lauryl sulfate and 10-20 parts of water. After the monomer smell disappears, filter, wash, and freeze-dry to obtain a toughened core-shell nanomaterial; The above components are stirred, mixed and ground to obtain the product.

2. The epoxy resin backside paint for pre-coated coiled material according to claim 1, characterized in that: The dispersant is one or more of BYK182, BYK183, and BYK185.

3. The epoxy resin backside paint for pre-coated coiled material according to claim 1, characterized in that: The solid epoxy resin is one or more of 601, 604, 607 and 609.

4. The epoxy resin backside paint for pre-coated coiled material according to claim 1, characterized in that: The liquid epoxy resin is one or two of 618, 6101 or 634.

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