A high weather-resistant solvent-free epoxy coating and its preparation method

Abstract

This invention discloses a high-weather-resistant solvent-free epoxy coating and its preparation method. The raw materials for preparing the solvent-free epoxy coating consist of a main agent and a curing agent. The main agent includes hydrogenated epoxy resin; the curing agent is a modified alicyclic amine, which is an adduct of alicyclic diamine and epoxy. This invention uses hydrogenated epoxy resin as the main film-forming agent, combined with a modified alicyclic diamine as the curing agent. The resulting solvent-free epoxy coating does not contain aromatic rings or aromatic ether bonds in its molecular structure, and the polymer molecular structure is not easily degraded by ultraviolet light, exhibiting strong adhesion, excellent resistance to yellowing, and outdoor durability. The synthesized modified alicyclic amine curing agent, an adduct of alicyclic diamine and epoxy, has no aromatic ring structure in its molecular structure and exhibits good resistance to photoaging. The solvent-free epoxy coating prepared by this invention can be directly used as a topcoat and primer, and the coating film has good weather resistance, corrosion resistance, and chemical resistance.

Description

Technical Field

[0001] This invention belongs to the field of coating and chemical technology, specifically relating to a high weather-resistant solvent-free epoxy coating and its preparation method. Background Technology

[0002] Currently, the main types of primer and topcoat coatings used on metal substrates under conventional spraying methods include solvent-free epoxy coatings, high-solids polyurethane resin coatings, fluorocarbon resin coatings, and alkyd resin coatings.

[0003] Solvent-free epoxy resin coatings typically use bisphenol A liquid epoxy resin and alicyclic amine curing agents. Because epoxy resin molecules contain aromatic rings and aromatic ether bonds, the cured film undergoes molecular degradation and chain breakage under ultraviolet radiation, resulting in poor weather resistance. Outdoor use often leads to chalking, loss of gloss, and discoloration, generally requiring a matching weather-resistant topcoat. High-solids polyurethane resin coatings and fluorocarbon resin coatings use low-viscosity resins combined with HDI trimer curing agents, resulting in good weather resistance. However, their adhesion and chemical resistance are inferior to epoxy resin coatings, and the high volatile organic compound (VOC) content of these paints poses a significant risk to workers and the atmospheric environment due to large amounts of organic solvent emissions. Alkyd resin coatings are single-component air-drying coatings, easy to apply, but have high VOC content, and their film exhibits poor weather resistance, corrosion resistance, and chemical resistance, failing to meet the demands of high-performance coatings.

[0004] Therefore, there is an urgent need to develop a simple, high-performance, and environmentally friendly integrated base and topcoat coating that can simultaneously achieve high corrosion resistance, high weather resistance, and high chemical resistance. Summary of the Invention

[0005] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention proposes a high weather-resistant solvent-free epoxy coating and its preparation method, wherein the solvent-free epoxy coating has good weather resistance, corrosion resistance, and chemical resistance.

[0006] To solve the above-mentioned technical problems, the first aspect of the present invention provides a solvent-free epoxy coating, the raw materials of which are composed of a main agent and a curing agent, wherein the raw material components of the main agent include hydrogenated epoxy resin; and the curing agent is a modified alicyclic amine, wherein the modified alicyclic amine is an adduct of alicyclic diamine and epoxy.

[0007] Specifically, this invention uses hydrogenated epoxy resin as the main film-forming agent. Its molecular structure is similar to that of traditional bisphenol A epoxy resin, but the aromatic rings within the molecule are hydrogenated to form alicyclic rings. This allows it to retain the reactivity and high adhesion of bisphenol A type epoxy resin, while the absence of aromatic rings and aromatic ether bonds makes it less susceptible to UV degradation. This results in epoxy coatings with strong adhesion and excellent resistance to yellowing and outdoor durability. Simultaneously, a modified alicyclic amine is used as the curing agent. This modified alicyclic amine is an adduct of alicyclic diamine and epoxy. Alicyclic diamines have low viscosity, low toxicity, and good color stability, but the primary amine in their molecular structure is highly reactive and reacts rapidly with epoxy groups, easily leading to a short activation period during application and other adverse side reactions. By undergoing an addition reaction with epoxy compounds, the primary amine content in the molecule is reduced, lowering the reactivity while improving compatibility with epoxy resin. This also gives the curing agent higher urethane stability and reduces side reactions with carbon dioxide and water vapor in the air. Meanwhile, the adduct of alicyclic diamine and epoxy has no aromatic ring structure in its molecular structure and has good resistance to photoaging.

[0008] As a further improvement to the above scheme, the mass ratio of the main agent to the curing agent is (4-7):1.

[0009] Preferably, the mass ratio of the main agent to the curing agent is (6-7):1.

[0010] As a further improvement to the above scheme, the viscosity of the hydrogenated epoxy resin at room temperature is 1500-3000 cPs.

[0011] As a further improvement to the above scheme, the epoxy equivalent of the hydrogenated epoxy resin is 200-230 g / eq.

[0012] As a further improvement to the above scheme, the preparation process of the modified alicyclic amine includes the following steps: first, salicylic acid is dissolved in an organic solvent, an alicyclic diamine is added, and the mixture is obtained to obtain an alicyclic amine solution; then, the alicyclic amine solution is mixed with epoxy resin and aliphatic glycidyl ether ester to carry out an addition reaction to obtain the modified alicyclic amine.

[0013] Specifically, in the preparation process of the modified alicyclic amine of the present invention, after the alicyclic diamine undergoes an addition reaction with the epoxy compound, it not only improves the compatibility between the amine compound and the epoxy resin, but also greatly reduces the reactivity of the primary amine, so that the epoxy coating prepared has a long application period and maintains excellent mechanical properties and chemical resistance.

[0014] Preferably, the alicyclic diamine is 3,3'-dimethyl-4,4-diaminodicyclohexylmethane or methylcyclohexanediamine.

[0015] Preferably, the aliphatic glycidyl ether ester is C 12 -C 13 Alkyl glycidyl ether or tert-butyl glycidyl ester.

[0016] Preferably, the organic solvent is propylene glycol methyl ether.

[0017] Preferably, the epoxy resin is a hydrogenated epoxy resin, and the hydrogenated epoxy resin is the same as the hydrogenated epoxy resin in the main agent.

[0018] As a further improvement to the above scheme, the mass ratio of the alicyclic diamine, epoxy resin and aliphatic glycidyl ether ester is 13:(0.5-1.5):(1-2).

[0019] Preferably, the mass ratio of the alicyclic diamine, epoxy resin and aliphatic glycidyl ether ester is 13:(0.8-1.2):(1.2-1.5).

[0020] Preferably, the temperature of the addition reaction is 38-45°C.

[0021] Preferably, the addition reaction takes 3-6 hours.

[0022] As a further improvement to the above scheme, the raw material components of the main agent also include at least one of the following: reactive diluent, dispersant, defoamer, thixotropic agent, stabilizer, titanium dioxide, filler, and reactive anti-rust pigment.

[0023] Preferably, the raw material components of the main agent, by weight, include:

[0024]

[0025]

[0026] Preferably, the reactive diluent is selected from 1,4-butanediol diglycidyl ether, C 12 -C 13 Alkyl glycidyl ether, C 12 -C 14 At least one of alkyl glycidyl ethers.

[0027] Preferably, the dispersant is selected from polyphosphate compounds and / or highly branched polyester polymers.

[0028] Preferably, the defoamer is selected from acrylate polymers and / or modified polysiloxane polymers.

[0029] Preferably, the thixotropic agent is selected from bentonite and / or modified hydrogenated castor oil.

[0030] Preferably, the stabilizer is selected from hindered amine stabilizers and / or benzotriazole stabilizers.

[0031] Preferably, the titanium dioxide is rutile titanium dioxide;

[0032] Preferably, the filler is selected from at least one of barite, silica powder, and sericite.

[0033] Preferably, the active rust-preventive pigment is selected from at least one of zinc phosphate, zinc phosphomolybdate, and aluminum tripolyphosphate.

[0034] Specifically, this invention uses phosphate as an active anti-rust pigment. The active phosphate ions generated by the hydrolysis of phosphate salts passivate and complex with the metal substrate to form a stable compound, which can effectively prevent oxidation and corrosion of the metal surface.

[0035] A second aspect of the present invention provides a method for preparing the solvent-free epoxy coating described in the first aspect, comprising the following steps:

[0036] (1) After diluting the hydrogenated epoxy resin, add other raw materials for preparing the main agent and disperse them to obtain the main agent;

[0037] (2) The main agent obtained in step (1) is mixed with the modified cycloaliphatic amine to obtain the solvent-free epoxy coating.

[0038] As a further improvement to the above solution, the method for preparing the solvent-free epoxy coating includes the following steps:

[0039] (1) Add hydrogenated epoxy resin and reactive diluent to the reactor according to the mass ratio, and disperse at medium speed (600-800 rpm) until uniform; then add thixotropic agent under low speed dispersion (200-400 rpm), and then disperse at high speed (1000-1200 rpm) for shear activation; finally add dispersant, defoamer, stabilizer, titanium dioxide, filler and reactive anti-rust pigment in sequence, disperse at high speed (1000-1200 rpm) for 30-50 minutes until the fineness is ≤50μm, filter, and obtain the main agent.

[0040] (2) The main agent obtained in step (1) and the modified cycloaliphatic amine are mixed evenly according to the mass ratio to obtain the solvent-free epoxy coating.

[0041] The third aspect of the present invention provides the application of the solvent-free epoxy coating described in the first aspect on the surface of a metal substrate.

[0042] Compared with the prior art, the above-described technical solution of the present invention has at least the following technical effects or advantages:

[0043] This invention utilizes hydrogenated epoxy resin as the main film-forming agent, combined with a modified alicyclic diamine as the curing agent, to produce a solvent-free epoxy coating. The resulting coating contains no aromatic rings or aromatic ether bonds in its molecular structure, making the polymer molecule less susceptible to UV degradation. It exhibits strong adhesion, excellent resistance to yellowing, and superior outdoor durability. The synthesized modified alicyclic amine curing agent is an adduct of alicyclic diamine and epoxy, reducing the primary amine content in the molecule, lowering reactivity, and improving compatibility with epoxy resin. It also enhances the curing agent's urethane stability, reducing side reactions with carbon dioxide and water vapor in the air. Furthermore, compared to primary amines, the adduct of alicyclic diamine and epoxy has lower volatility and corrosivity, and the absence of aromatic rings in its molecular structure contributes to its excellent resistance to photoaging.

[0044] The solvent-free epoxy coating prepared by this invention can be directly used as a base and topcoat coating for metal substrates. The coating film has excellent surface appearance, high gloss, fullness, mechanical properties, salt spray resistance, weather resistance and chemical resistance, and has excellent long-term anti-corrosion performance. Detailed Implementation

[0045] The present invention will now be described in detail with reference to embodiments to facilitate understanding of the invention by those skilled in the art. It is particularly important to note that the embodiments are merely illustrative of the invention and should not be construed as limiting the scope of protection of the invention. Non-essential improvements and adjustments made to the invention by those skilled in the art based on the above description should still fall within the scope of protection of the invention. Furthermore, all raw materials mentioned below, unless otherwise specified, are commercially available products; all process steps or preparation methods not mentioned in detail are process steps or preparation methods known to those skilled in the art.

[0046] The raw materials used in the embodiments and comparative examples of this invention are specifically selected from the following types of raw materials:

[0047] Hydrogenated epoxy resin: ADEKA RESIN EP-4080E (viscosity at room temperature is 2300 cPs, epoxy equivalent is 215 g / eq);

[0048] Reactive diluent: 750 748、 759;

[0049] Dispersant: FA 4620, DISPERBYK-2152;

[0050] Defoamers: Airex 900, AFCONA 2270;

[0051] Thixotropic agents: organic modified bentonite BENGEL 828, modified hydrogenated castor oil THIXATROL ST;

[0052] Stabilizer: 123. 384-2;

[0053] Leveling agent: BYK-333 FL 3777;

[0054] Drying agent: Changfeng ZHV-8.

[0055] Example 1

[0056] A solvent-free epoxy coating is prepared by means of a main agent and a curing agent, wherein the main agent comprises, by weight, the following components:

[0057]

[0058]

[0059] The curing agent is a modified alicyclic amine, and the mass ratio of the main agent to the curing agent is 7:1.

[0060] A method for preparing a solvent-free epoxy coating includes the following steps:

[0061] (1) Synthesis of modified alicyclic amine: First, 0.7 parts by weight of salicylic acid was dissolved in 1.3 parts by weight of propylene glycol methyl ether, and 40.5 parts by weight of 3,3'-dimethyl-4,4-diaminodicyclohexylmethane was added and stirred evenly to obtain an alicyclic amine solution; then 3.4 parts by weight of hydrogenated epoxy resin and 4.1 parts by weight of C 12 -C 13 After the alkyl glycidyl ethers are mixed evenly, they are slowly added dropwise to the prepared alicyclic amine solution, and the addition reaction is carried out at 40°C for 5 hours while stirring at 500 rpm. After cooling, the mixture is filtered to obtain the modified alicyclic amine curing agent.

[0062] (2) Preparation of the main agent: Hydrogenated epoxy resin and reactive diluent are added to the reactor according to the raw material components of the main agent and dispersed evenly at a speed of 600 rpm. Thixotropic agent is added under the condition of dispersion at 300 rpm, and then dispersed and sheared at 1000 rpm for 15 minutes. Dispersant, defoamer, stabilizer, titanium dioxide, barite (800 mesh) and reactive anti-rust pigment are added in sequence and dispersed at 1000 rpm for 40 minutes until the fineness is ≤50μm. After filtration, the main agent is obtained.

[0063] (3) Preparation of solvent-free epoxy coating: The main agent obtained in step (2) and the modified cycloaliphatic amine curing agent obtained in step (1) are stirred evenly at a mass ratio of 7:1 to obtain the solvent-free epoxy coating of this embodiment.

[0064] Example 2

[0065] A solvent-free epoxy coating is prepared by means of a main agent and a curing agent, wherein the main agent comprises, by weight, the following components:

[0066]

[0067]

[0068] The curing agent is a modified alicyclic amine, and the mass ratio of the main agent to the curing agent is 6:1.

[0069] A method for preparing a solvent-free epoxy coating includes the following steps:

[0070] (1) Synthesis of modified alicyclic amine: First, 0.7 parts by weight of salicylic acid was dissolved in 1.3 parts by weight of propylene glycol methyl ether, and 40.5 parts by weight of methylcyclohexanediamine was added and stirred evenly to obtain an alicyclic amine solution; then, 3.4 parts by weight of hydrogenated epoxy resin and 4.1 parts by weight of glycidyl tert-carbonate were mixed evenly and slowly added dropwise to the prepared alicyclic amine solution, and the addition reaction was carried out at 40°C for 5 hours while stirring at 500 rpm. After cooling, the mixture was filtered to obtain the modified alicyclic amine curing agent.

[0071] (2) Preparation of the main agent: Hydrogenated epoxy resin and reactive diluent are added to the raw material components of the main agent in the reactor and dispersed evenly at a speed of 600 rpm. Thixotropic agent is added under the condition of dispersion at 300 rpm, and then dispersed and sheared at 1000 rpm for 15 minutes. Dispersant, defoamer, stabilizer, titanium dioxide, barite (800 mesh), sericite (1250 mesh) and reactive anti-rust pigment are added in sequence and dispersed at 1000 rpm for 40 minutes until the fineness is ≤50μm. After filtration, the main agent is obtained.

[0072] (3) Preparation of solvent-free epoxy coating: The main agent obtained in step (2) and the modified cycloaliphatic amine curing agent obtained in step (1) are stirred evenly at a mass ratio of 6:1 to obtain the solvent-free epoxy coating of this embodiment.

[0073] Example 3

[0074] A solvent-free epoxy coating is prepared by means of a main agent and a curing agent, wherein the main agent comprises, by weight, the following components:

[0075]

[0076] The curing agent is a modified alicyclic amine, and the mass ratio of the main agent to the curing agent is 7:1.

[0077] A method for preparing a solvent-free epoxy coating includes the following steps:

[0078] (1) Synthesis of modified alicyclic amine: First, 0.7 parts by weight of salicylic acid was dissolved in 1.3 parts by weight of propylene glycol methyl ether, and 40.5 parts by weight of 3,3'-dimethyl-4,4-diaminodicyclohexylmethane was added and stirred evenly to obtain an alicyclic amine solution; then 3.4 parts by weight of hydrogenated epoxy resin and 4.1 parts by weight of C 12 -C 13 After the alkyl glycidyl ethers are mixed evenly, they are slowly added dropwise to the prepared alicyclic amine solution, and the addition reaction is carried out at 40°C for 5 hours while stirring at 500 rpm. After cooling, the mixture is filtered to obtain the modified alicyclic amine curing agent.

[0079] (2) Preparation of the main agent: Hydrogenated epoxy resin and reactive diluent are added to the reactor according to the raw material components of the main agent and dispersed evenly at a speed of 600 rpm. Thixotropic agent is added under the condition of dispersion at 300 rpm, and then dispersed and sheared at 1000 rpm for 15 minutes. Dispersant, defoamer, stabilizer, titanium dioxide, silica powder (800 mesh) and reactive anti-rust pigment are added in sequence and dispersed at 1000 rpm for 40 minutes until the fineness is ≤50μm. After filtration, the main agent is obtained.

[0080] (3) Preparation of solvent-free epoxy coating: The main agent obtained in step (2) and the modified cycloaliphatic amine curing agent obtained in step (1) are stirred evenly at a mass ratio of 7:1 to obtain the solvent-free epoxy coating of this embodiment.

[0081] Comparative Example 1

[0082] A solvent-free epoxy coating is prepared by means of a main agent and a curing agent, wherein the main agent comprises, by weight, the following components:

[0083]

[0084] The curing agent is an alicyclic amine curing agent. EC 331, and the mass ratio of the main agent to the curing agent is 5:1.

[0085] A method for preparing a solvent-free epoxy coating includes the following steps:

[0086] (1) Preparation of curing agent: Add 98 parts by weight of alicyclic amine curing agent to the reaction vessel. EC 331 and 2 parts by weight of benzyl alcohol are mixed evenly to obtain a curing agent.

[0087] (2) Preparation of the main agent: Epoxy resin, reactive diluent and benzyl alcohol are added to the reactor according to the raw material components of the main agent. The mixture is dispersed evenly at 600 rpm. Thixotropic agent is added under the condition of dispersion at 300 rpm. Then, the mixture is dispersed and sheared for 15 minutes at 1000 rpm. Dispersant, defoamer, stabilizer, titanium dioxide, silica powder (800 mesh) and reactive anti-rust pigment are added in sequence. The mixture is dispersed at 1000 rpm for 60 minutes until the fineness is ≤60μm. After filtration, the main agent is obtained.

[0088] (3) Preparation of solvent-free epoxy coating: The main agent obtained in step (2) and the curing agent obtained in step (1) are stirred evenly at a mass ratio of 5:1 to obtain the solvent-free epoxy coating of this comparative example.

[0089] Comparative Example 2

[0090] A polyurethane coating is prepared by means of a main agent and a curing agent, wherein the main agent comprises, by weight, the following components:

[0091]

[0092] The curing agent is an HDI trimer curing agent, and the mass ratio of the main agent to the curing agent is 9:1.

[0093] A method for preparing a polyurethane coating includes the following steps:

[0094] (1) Preparation of curing agent: Add 14 parts by mass of trimethylbenzene and 1 part by mass of TI dehydrating agent to the reactor, stir evenly at 300 rpm, and add 85 parts by mass of HDI trimer curing agent to obtain curing agent.

[0095] (2) Preparation of the main agent: Hydroxy acrylic resin and xylene were added to the reactor according to the raw material components of the main agent and dispersed evenly at 600 rpm. Thixotropic agent was added under the condition of dispersion at 300 rpm, and then dispersed and sheared for 15 minutes at 1000 rpm. Dispersant, defoamer, titanium dioxide, heavy calcium carbonate powder (800 mesh) and active anti-rust pigment were added in sequence and dispersed at 1000 rpm for 40 minutes until the fineness was ≤50μm. Then light stabilizer and leveling agent were added and stirred evenly at 300 rpm. After filtration, the main agent was obtained.

[0096] (3) Preparation of polyurethane coating: The main agent obtained in step (2) and the curing agent obtained in step (1) are stirred evenly at a mass ratio of 9:1 to obtain the polyurethane coating of this comparative example.

[0097] Comparative Example 3

[0098] A two-component, room-temperature curing fluorocarbon coating is prepared by means of a main agent and a curing agent, wherein the main agent comprises, by weight, the following components:

[0099]

[0100]

[0101] The curing agent is an HDI trimer curing agent, and the mass ratio of the main agent to the curing agent is 6:1.

[0102] A method for preparing a solvent-free epoxy coating includes the following steps:

[0103] (1) Preparation of curing agent: Add 39 parts by mass of xylene and 1 part by mass of TI dehydrating agent to the reactor, stir evenly at 300 rpm, and add 60 parts by mass of HDI trimer curing agent to obtain curing agent.

[0104] (2) Preparation of the main agent: In the reaction vessel, solvent-based FEVE fluorocarbon resin and xylene are added according to the raw material components of the main agent and dispersed evenly at a speed of 600 rpm. Thixotropic agent and polyamide wax powder are added under the condition of dispersion at 300 rpm, and then dispersed and sheared at 1000 rpm for 15 minutes. Dispersant, defoamer, titanium dioxide and silica powder (1500 mesh) are added in sequence and dispersed at 1000 rpm for 50 minutes until the fineness is ≤50μm. Then, light stabilizer and leveling agent are added and stirred evenly at 300 rpm. After filtration, the main agent is obtained.

[0105] (3) Preparation of two-component room temperature curing fluorocarbon coating: The main agent obtained in step (2) and the curing agent obtained in step (1) are stirred evenly at a mass ratio of 6:1 to obtain the two-component room temperature curing fluorocarbon coating of this comparative example.

[0106] Comparative Example 4

[0107] A one-component alkyd coating, wherein the raw material components, by weight, include:

[0108]

[0109] A method for preparing a one-component alkyd coating includes the following steps:

[0110] In a reaction vessel, long-oil alkyd resin and xylene were added according to the raw material components of the main agent and dispersed evenly at 600 rpm. Thixotropic agent was added under dispersion conditions of 300 rpm, and then dispersed and sheared at 1000 rpm for 15 minutes. Dispersant, titanium dioxide, heavy calcium carbonate powder (800 mesh), and active anti-rust pigment were added in sequence and dispersed at 1000 rpm for 50 minutes until the fineness was ≤50μm. Then, drier was added and stirred evenly at 300 rpm. After filtration, the single-component alkyd coating of this comparative example was obtained.

[0111] Comparative Example 5

[0112] A solvent-free epoxy coating is prepared by means of a main agent and a curing agent, wherein the main agent comprises, by weight, the following components:

[0113]

[0114] The curing agent is ANCAMINE 1618 modified alicyclic amine curing agent, and the mass ratio of the main agent to the curing agent is 3.5:1.

[0115] A method for preparing a solvent-free epoxy coating includes the following steps:

[0116] (1) Preparation of the main agent: Hydrogenated bisphenol A type epoxy resin and reactive diluent were added to the reactor according to the raw material components of the main agent and dispersed evenly at a speed of 600 rpm. Polyamide wax was added under the condition of dispersion at 300 rpm and then dispersed and sheared at 1000 rpm for 15 minutes. Dispersant, defoamer, titanium dioxide, silica powder (800 mesh) and barium sulfate (800 mesh) were added in sequence and dispersed at 1000 rpm for 40 minutes until the fineness was ≤50μm. After filtration, the main agent was obtained.

[0117] (2) Preparation of solvent-free epoxy coating: The main agent obtained in step (1) is mixed with ANCAMINE 1618 modified cycloaliphatic amine curing agent at a mass ratio of 3.5:1 to obtain the solvent-free epoxy coating of this comparative example.

[0118] Performance testing

[0119] The coatings prepared in Examples 1-3 and Comparative Examples 1-5 were sprayed in one coat onto pretreated carbon steel plates (surface cleanliness Sa2.5 grade, surface roughness 40-70μm). After curing at 23±2℃ for 14 days, the performance of the coating film was tested, as shown in Tables 1 and 2.

[0120] Table 1: Performance Test Results of Solvent-Free Epoxy Coatings in Examples 1-3

[0121]

[0122]

[0123] Table 2: Performance test results of the coatings in Comparative Examples 1-5

[0124]

[0125]

[0126] As shown in Tables 1 and 2, the coatings of Examples 1-3 have a non-volatile content of ≥98%, a volatile organic compound content of ≤50g / L, and a solid content similar to that of the coating of Comparative Example 1; while the coatings of Comparative Examples 2-4 have low solid content, high VOC emissions, and low film thickness in one coat.

[0127] Meanwhile, the coatings of Examples 1-3, Comparative Examples 1, and Comparative Examples 5 all exhibited adhesion greater than 10 MPa, significantly superior to the coatings of Comparative Examples 2-4. However, the coatings of Examples 1-3 demonstrated a neutral salt spray resistance of 2500 hours, far exceeding that of Comparative Examples 1-5. This is primarily because the film-forming molecules of the coatings of Examples 1-3 lack aromatic rings and aromatic ether bonds, making them less susceptible to UV degradation and exhibiting better weather resistance. Furthermore, the xenon lamp accelerated aging resistance of the coatings of Examples 1-3 was consistent with that of the fluorocarbon coatings, reaching 3000 hours, with discoloration, gloss loss, and chalking all below grade 1, while the epoxy coating of Comparative Example 1 showed severe discoloration, gloss loss, and chalking problems within 100 hours.

[0128] For those skilled in the art, several simple deductions or substitutions can be made without departing from the inventive concept, without requiring creative effort. Therefore, any simple improvements made to this invention by those skilled in the art based on the disclosure of this invention should be within the scope of protection of this invention. The above embodiments are preferred embodiments of this invention, and all processes similar to this invention and equivalent changes should fall within the scope of protection of this invention.

Claims

1. A solvent-free epoxy coating, characterized in that, Includes main agent and curing agent, The raw material components of the main agent, by weight, include: 35-45 parts of hydrogenated epoxy resin; 4-7 parts reactive diluent; Dispersant 0.3-0.5 parts; Defoamer 0.2-0.4 parts; Thixotropic agent 0.3-2 parts; Stabilizer 0.8-1.5 parts; 20-30 parts titanium dioxide; 10-20 parts of filler; 10-20 parts of active rust-preventive pigment; The hydrogenated epoxy resin is ADEKA RESIN EP-4080E; The active diluent is selected from at least one of 1,4-butanediol diglycidyl ether, C12-C13 alkyl glycidyl ether, and C12-C14 alkyl glycidyl ether. The active rust-preventive pigment is selected from at least one of zinc phosphate, zinc phosphomolybdate, and aluminum tripolyphosphate; The curing agent is a modified alicyclic amine, which is an adduct of an alicyclic diamine and an epoxy. The preparation process of the modified alicyclic amine includes the following steps: first, salicylic acid is dissolved in an organic solvent, an alicyclic diamine is added, and the mixture is obtained to obtain an alicyclic amine solution; then, the alicyclic amine solution is mixed with the hydrogenated epoxy resin and the aliphatic glycidyl ether ester, and an addition reaction is carried out at 38-45°C for 3-6 hours to obtain the modified alicyclic amine. The alicyclic diamine is 3,3'-dimethyl-4,4-diaminodicyclohexylmethane or methylcyclohexanediamine, and the aliphatic glycidyl ether ester is C12-C13 alkyl glycidyl ether or tertiary glycidyl carbonate ester. The mass ratio of the alicyclic diamine, hydrogenated epoxy resin and aliphatic glycidyl ether ester is 13:(0.5-1.5):(1-2).

2. The solvent-free epoxy coating according to claim 1, characterized in that, The mass ratio of the main agent to the curing agent is (4-7):

1.

3. The solvent-free epoxy coating according to claim 1, characterized in that, The raw material components of the main agent also include at least one of the following: reactive diluent, dispersant, defoamer, thixotropic agent, stabilizer, titanium dioxide, filler, and reactive anti-rust pigment.

4. A method for preparing a solvent-free epoxy coating as described in any one of claims 1 to 3, characterized in that, Includes the following steps: (1) After diluting the hydrogenated epoxy resin, add other raw materials for preparing the main agent and disperse them to obtain the main agent; (2) The main agent obtained in step (1) is mixed with the modified cycloaliphatic amine to obtain the solvent-free epoxy coating.

5. The application of the solvent-free epoxy coating according to any one of claims 1 to 3 on the surface of a metal substrate.

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