Solvent-free epoxy coating

Abstract

The invention relates to the field of coatings, in particular to a solvent-free epoxy coating. The solvent-free epoxy coating comprises a component A and a component B, wherein the component A comprises bisphenol A type epoxy resin, a reactive diluent, a flatting agent, a defoaming agent and an anti-settling agent; and the component B comprises a curing agent oxalic acid modified isophorone diamine and a Mannich base modified diethylenetriamine. After the curing agent provided by the invention is used, the surface drying time and the hard drying time are obviously improved, and the coating can be completely cured more quickly, so that the coating can be subjected to subsequent processing treatment or put into use in advance, and the whole production process is accelerated.

Description

Technical Field

[0001] The invention relates to the field of coatings, in particular to solvent-free epoxy coatings. Background Art

[0002] In the current field of coating technology, for some curing agents, the curing process is relatively slow. Under standard environmental conditions, it often takes several hours or even longer to achieve a basic degree of drying, which greatly prolongs the coating construction cycle, increases time and labor costs, reduces production efficiency, and cannot meet the requirements of modern industrial rapid production. For example, the waiting time for multi-layer coating is prolonged, and in some industrial production lines with strict requirements on production efficiency, it has become a bottleneck factor restricting the increase in production capacity.

[0003] What is more serious is that the coating formed by the existing paint curing agent has very poor firmness and is very easy to fall off. After the coating is applied to the surface of the coated substrate, when it is subjected to conventional environmental stress, such as periodic temperature changes and humidity fluctuations, after a short period of several weeks, it was found through microscopic observation and adhesion testing equipment that the adhesion between the coating and the substrate decreased significantly, and large-scale peeling occurred. In some outdoor facility application scenarios, such as decorative coatings on building exterior walls and traffic signs, the shedding of the coating not only seriously affects its aesthetics, but also makes the coated objects lose their due protective function and accelerates the corrosion and damage of the substrate. This not only shortens the service life of the coating, but also increases the cost of maintenance and re-coating.

[0004] In terms of hardness and wear resistance, the hardness of the cured coating is insufficient. When tested, the hardness value does not meet the standard. It is difficult to resist slight friction and scratches in daily use, and is prone to scratches and wear, causing the decorative and protective properties of the coating to decline rapidly. It is unable to provide long-lasting and reliable protection for the coated objects, greatly limiting its application in fields with high requirements for wear resistance.

[0005] In summary, the performance of existing coating curing agents is not superior and it is difficult to meet the growing and diversified needs of various industries. There is an urgent need for a new type of high-performance coating curing agent to overcome these problems, thereby promoting the further development and application expansion of coating technology. Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a solvent-free epoxy coating, which solves the technical problem that it takes several hours or even longer to reach a basic drying degree under standard environmental conditions.

[0008] (II) Technical solution

[0009] In a first aspect, the present invention provides a solvent-free epoxy coating, which comprises a component A and a component B, wherein the component A comprises a bisphenol A type epoxy resin, a reactive diluent, a leveling agent, a defoaming agent and an anti-settling agent;

[0010] Component B includes curing agents oxalic acid-modified isophorone diamine and Mannich base-modified diethylene triamine.

[0011] Optionally, component A includes the following raw materials in parts by weight: 40-50 parts of bisphenol A epoxy resin, 5-10 parts of reactive diluent, 0.1-0.5 parts of leveling agent, 0.1-0.5 parts of defoaming agent, and 0.2-0.5 parts of anti-settling agent;

[0012] The second component comprises the following raw materials in parts by weight: 60-70 parts by weight of curing agent oxalic acid-modified isophorone diamine and Mannich base-modified diethylene triamine.

[0013] Optionally, component A includes the following raw materials in parts by weight: 42-48 parts of bisphenol A epoxy resin, 7-9 parts of active diluent, 0.2-0.4 parts of leveling agent, 0.2-0.4 parts of defoaming agent, and 0.3-0.5 parts of anti-settling agent;

[0014] The second component comprises the following raw materials in parts by weight: curing agent oxalic acid modified isophorone diamine and Mannich base modified diethylene triamine, with a total weight of 62-70 parts.

[0015] Optionally, component A includes the following raw materials in parts by weight: 45 parts of bisphenol A epoxy resin, 8 parts of reactive diluent, 0.3 parts of leveling agent, 0.3 parts of defoaming agent, and 0.5 parts of anti-settling agent;

[0016] Component B includes the following raw materials in parts by weight: 70 parts by weight of oxalic acid-modified isophorone diamine and Mannich base-modified diethylenetriamine curing agent.

[0017] Optionally, the curing agent includes 30-35 parts of oxalic acid modified isophorone diamine and 30-35 parts of Mannich base modified diethylene triamine.

[0018] Optionally, the bisphenol A epoxy resin is one or both of bisphenol A epoxy resin 128 and E51;

[0019] The active diluent is one or both of 1,4-butanediol diglycidyl ether and neopentyl glycol diglycidyl ether;

[0020] The defoamer is one or both of defoamer A530 and defoamer 088;

[0021] The leveling agent is one or more of leveling agent BYK-320, leveling agent BYK-333 and leveling agent EFKA 3772;

[0022] The anti-settling agent is organic bentonite BS-1C.

[0023] Optionally, isophorone diamine and solvent xylene are added to a container, stirred, then oxalic acid is added, and then a catalyst toluenesulfonic acid is added; the reaction system is slowly heated to 100-180°C, stirred at the reaction temperature, and reacted for 4-12 hours; samples are taken at regular intervals, and the changes in acid value or amine value are determined by acid-base titration. When the changes in acid value and amine value are not obvious, the reaction is completed; the solvent in the reaction system is removed by reduced pressure distillation, and finally dried at 40-60°C for 12-24 hours to obtain an oxalic acid-modified isophorone diamine product.

[0024] Optionally, benzaldehyde, diethylenetriamine and phenol are used as raw materials, hydrochloric acid is used as a catalyst, and the reaction is carried out in an ethanol solution, the reaction temperature is 50°C-100°C, and the reaction time is 2h-8h; after the reaction is completed, the solvent is removed by reduced pressure distillation to obtain a crude product. The crude product can be dissolved in hot ethanol, filtered while hot to remove insoluble impurities, and then cooled for crystallization, filtered, and dried to obtain a Mannich base modified diethylenetriamine product.

[0025] (III) Beneficial effects

[0026] After using the curing agent of the present invention, the coating that may take several hours to dry on the surface may be able to reach the dry state in tens of minutes, which greatly improves the construction efficiency and reduces the waiting time. It is particularly suitable for large-scale coating projects or production scenarios that require rapid turnover.

[0027] The actual drying time is also significantly improved, allowing the coating to fully cure faster, so that subsequent processing or use can be carried out in advance, speeding up the entire production process;

[0028] The curing agent of the present invention can ensure that the coating can be firmly attached to various substrates, and can effectively prevent the coating from peeling and bubbling under adverse conditions such as high temperature, humidity, and vibration, thereby reducing the rework and maintenance costs caused by coating shedding;

[0029] In building exterior wall paint, good adhesion can make the paint remain stable for a long time under the influence of natural environmental factors such as wind, sun, and rain, and it is not easy to fall off, avoiding the potential threat to pedestrian safety caused by coating shedding and reducing the frequency and cost of building maintenance. DETAILED DESCRIPTION

[0030] In order to better explain the present invention and facilitate understanding, the present invention is described in detail through specific implementation methods.

[0031] The present invention provides a solvent-free epoxy coating, which comprises a component A and a component B, wherein the component A comprises a bisphenol A type epoxy resin, an active diluent, a leveling agent, a defoaming agent and an anti-settling agent;

[0032] Component B includes curing agents oxalic acid-modified isophorone diamine and Mannich base-modified diethylene triamine.

[0033] Mannich base modified amines can cure bisphenol A epoxy resins quickly at lower temperatures. This is because the active groups in the Mannich base (such as secondary amine groups) can react quickly with epoxy groups. In some winter construction or occasions where high curing speed is required, the use of Mannich base modified amine epoxy curing agents can effectively shorten the curing time. Because different groups (such as phenolic or ketone groups) are introduced into the molecular structure of Mannich base modified amines, compared with traditional amine curing agents, it can give the cured epoxy resin better flexibility. This allows the cured product to better resist external impact and reduce the possibility of cracking.

[0034] The introduction of carboxylic acid groups can improve the compatibility of curing agents with bisphenol A epoxy resins. Bisphenol A epoxy resins themselves contain groups such as epoxy and hydroxyl groups. The carboxylic acid groups in carboxylic acid-modified amine curing agents can interact with these groups in bisphenol A epoxy resins, making the two mixed more evenly, thereby improving the curing effect. Bisphenol A epoxy resins cured with carboxylic acid-modified amine curing agents have excellent chemical corrosion resistance. Carboxylic acid groups can participate in the curing reaction to form more stable chemical bonds, enhancing the resistance of the cured product to chemicals such as acids and alkalis.

[0035] The active groups of the two curing agents can complement each other and fully react with the epoxy groups in bisphenol A epoxy resin. The secondary amine groups in Mannich base modified amines and the amine groups and carboxylic acid groups in carboxylic acid modified amines can react with epoxy groups, thereby improving the degree of curing of epoxy resins and making the cured products have better physical and chemical properties. When Mannich base modified amine curing agents and carboxylic acid modified amine curing agents are used in combination, the curing speed can be adjusted. Mannich base modified amine epoxy curing agents provide fast curing characteristics, while carboxylic acid modified amine curing agents can slightly moderate the curing speed to a certain extent, avoiding problems such as internal stress caused by over-rapid curing. In the curing process of some bisphenol A epoxy resin products, the combination of the two can make the curing process smoother and reduce deformation and cracking of the products.

[0036] Mannich base modified amine curing agent gives the cured product flexibility, and carboxylic acid modified amine curing agent can increase the hardness and strength of the cured product to a certain extent. The combination of the two can achieve a good balance of toughness and hardness in the cured product. The carboxylic acid group in the carboxylic acid modified amine curing agent can form some weather-resistant chemical bonds during the curing reaction, and the flexibility of the Mannich base modified amine curing agent also helps to reduce the damage of the cured product caused by environmental factors such as temperature changes, so that the cured product can be better used in outdoor environments.

[0037] The bisphenol A epoxy resin is one or more of bisphenol A epoxy resin 128 and E51 produced by Taiwan Nan Ya;

[0038] The active diluent is one or both of 1,4-butanediol diglycidyl ether and neopentyl glycol diglycidyl ether of Wuxi Xinyehao Chemical; the active diluent has the effect of reducing the viscosity of the system and increasing toughness, which can improve the construction efficiency and coating toughness of the solvent-free epoxy coating;

[0039] The defoamer is one or both of A530 and 088 of BYK Company;

[0040] The leveling agent is one or more of BYK-320, BYK-333 of BYK Company and EFKA 3772 of EFKA Company;

[0041] The anti-settling agent is BS-1C organic bentonite from Zhejiang Fenghong Company.

[0042] Example 1

[0043] The present embodiment provides a solvent-free epoxy coating, comprising two components, component A and component B, wherein component A comprises the following raw materials in parts by weight: 45 parts of bisphenol A epoxy resin 128, 8 parts of 1,4-butanediol diglycidyl ether, 0.3 parts of leveling agent BYK-320, 0.3 parts of defoaming agent A530, and 0.5 parts of BS-1C organic bentonite;

[0044] Component B includes the following raw materials in parts by weight: 32 parts of curing agent oxalic acid-modified isophorone diamine and 35 parts of Mannich base-modified diethylene triamine.

[0045] That is, component A includes the following components in percentage by mass (accounting for component A): bisphenol A epoxy resin 12882.9%, 1,4-butanediol diglycidyl ether 15%, leveling agent BYK-320 0.6%, defoamer A530 0.6%, BS-1C organic bentonite 0.9%;

[0046] Component B includes the following components in percentage by weight (accounting for component B): 48% of curing agent oxalic acid-modified isophorone diamine and 52% of Mannich base-modified diethylene triamine.

[0047] Preparation method of curing agent oxalic acid modified isophorone diamine:

[0048] Isophorone diamine and solvent xylene are added into a container, stirred, and then oxalic acid is slowly added, the molar ratio of isophorone diamine to oxalic acid is 1:1.2, and then a catalyst toluenesulfonic acid is added with a mass percentage of 3% of the total mass; the reaction system is slowly heated to 150°C, stirred at the reaction temperature, and reacted for 8 hours; samples are taken at regular intervals, and the changes in acid value or amine value are determined by acid-base titration. When the changes in acid value and amine value are not obvious, the reaction is completed; the solvent in the reaction system is removed by reduced pressure distillation, cooling crystallization and filtration are used for separation, and finally drying is performed at 50°C for 18 hours to obtain an oxalic acid-modified isophorone diamine product.

[0049] Preparation method of curing agent Mannich base modified diethylenetriamine:

[0050] Benzaldehyde, diethylenetriamine and phenol are used as raw materials, hydrochloric acid is used as a catalyst, benzaldehyde reacts with diethylenetriamine to generate an imine intermediate, and the intermediate reacts with phenol, the molar ratio of benzaldehyde, diethylenetriamine and phenol is 1.5:1:1, and the reaction is carried out in an ethanol solution, the reaction temperature is 80°C, and the reaction time is 6 hours; after the reaction is completed, the solvent is removed by reduced pressure distillation to obtain a crude product. The crude product can be dissolved in hot ethanol, filtered while hot to remove insoluble impurities, and then cooled for crystallization, filtered, and dried to obtain a Mannich base modified diethylenetriamine product.

[0051] Example 2

[0052] The present embodiment provides a solvent-free epoxy coating, comprising two components, component A and component B, wherein component A comprises the following raw materials in parts by weight: 40 parts of bisphenol A epoxy resin E51, 5 parts of neopentyl glycol diglycidyl ether, 0.1 parts of leveling agent BYK-333, 0.1 parts of defoaming agent 088, and 0.2 parts of BS-1C organic bentonite;

[0053] Component B includes the following raw materials in parts by weight: 30 parts of curing agent oxalic acid-modified isophorone diamine and 30 parts of Mannich base-modified diethylene triamine.

[0054] That is, component A includes the following components in percentage by mass (accounting for component A): 8.1% of bisphenol A epoxy resin E518, 11.1% of neopentyl glycol diglycidyl ether, 0.2% of leveling agent BYK-333, 0.2% of defoaming agent 088, and 0.4% of BS-1C organic bentonite;

[0055] Component B includes the following components in percentage by mass (accounting for component B): 50% of curing agent oxalic acid-modified isophorone diamine and 50% of Mannich base-modified diethylene triamine.

[0056] The preparation method of curing agent oxalic acid modified isophorone diamine and Mannich base modified diethylene triamine is the same as that of Example 1

[0057] Example 3

[0058] The present embodiment provides a solvent-free epoxy coating, comprising two components, component A and component B, wherein component A comprises the following raw materials in parts by weight: 50 parts of bisphenol A epoxy resin 128, 10 parts of 1,4-butanediol diglycidyl ether, 0.5 parts of leveling agent EFKA 3772, 0.5 parts of defoaming agent A530, and 0.5 parts of BS-1C organic bentonite;

[0059] Component B includes the following raw materials in parts by weight: 31 parts of curing agent oxalic acid-modified isophorone diamine and 35 parts of Mannich base-modified diethylene triamine.

[0060] That is, component A includes the following components in percentage by mass (accounting for component A): bisphenol A type epoxy resin 12881.3%, 1,4-butanediol diglycidyl ether 16.3%, leveling agent EFKA 37720.8%, defoaming agent A530 0.8%, BS-1C organic bentonite 0.8%;

[0061] Component B includes the following components in percentage by weight (accounting for component B): 47% of curing agent oxalic acid-modified isophorone diamine and 53% of Mannich base-modified diethylene triamine.

[0062] The preparation method of curing agent oxalic acid modified isophorone diamine and Mannich base modified diethylene triamine is the same as that of Example 1

[0063] Example 4

[0064] The present embodiment provides a solvent-free epoxy coating, comprising two components A and B, wherein the component A comprises the following raw materials in parts by weight: 42 parts of bisphenol A epoxy resin E51, 7 parts of neopentyl glycol diglycidyl ether, 0.2 parts of leveling agent BYK-333, 0.2 parts of defoaming agent A530, and 0.3 parts of BS-1C organic bentonite;

[0065] Component B includes the following raw materials in parts by weight: 32 parts of curing agent oxalic acid-modified isophorone diamine and 33 parts of Mannich base-modified diethylene triamine.

[0066] That is, component A includes the following components in percentage by mass (accounting for component A): bisphenol A epoxy resin E518 4.4%, neopentyl glycol diglycidyl ether 14.0%, leveling agent BYK-333 0.4%, defoaming agent A530 0.4%, BS-1C organic bentonite 0.8%;

[0067] Component B includes the following components in percentage by mass (accounting for component B): 49% of curing agent oxalic acid-modified isophorone diamine and 51% of Mannich base-modified diethylene triamine.

[0068] The preparation method of curing agent oxalic acid modified isophorone diamine and Mannich base modified diethylene triamine is the same as that of Example 1

[0069] Example 5

[0070] The present embodiment provides a solvent-free epoxy coating, comprising two components, component A and component B, wherein component A comprises the following raw materials in parts by weight: 48 parts of bisphenol A epoxy resin E51, 9 parts of 1,4-butanediol diglycidyl ether, 0.4 parts of leveling agent BYK-320, 0.4 parts of defoaming agent 088, and 0.5 parts of BS-1C organic bentonite;

[0071] Component B includes the following raw materials in parts by weight: 35 parts of curing agent oxalic acid-modified isophorone diamine and 31 parts of Mannich base-modified diethylene triamine.

[0072] That is, component A includes the following components in percentage by mass (accounting for component A): 2.3% of bisphenol A epoxy resin E518, 15.4% of 1,4-butanediol diglycidyl ether, 0.7% of leveling agent BYK-320, 0.7% of defoaming agent 088, and 0.9% of BS-1C organic bentonite;

[0073] Component B includes the following components in percentage by mass (accounting for component B): 53% of curing agent oxalic acid-modified isophorone diamine and 47% of Mannich base-modified diethylene triamine.

[0074] The preparation method of curing agent oxalic acid modified isophorone diamine and Mannich base modified diethylene triamine is the same as that of Example 1

[0075] Comparative Example 1

[0076] Component B is a curing agent, oxalic acid-modified isophorone diamine.

[0077] The rest is the same as in Example 1

[0078] Comparative Example 2

[0079] Component B is Mannich base modified diethylenetriamine.

[0080] The rest is the same as in Example 1

[0081] Comparative Example 3

[0082] Component B includes the following components in percentage by mass (accounting for component B): 25% of curing agent oxalic acid-modified isophorone diamine and 75% of Mannich base-modified diethylene triamine.

[0083] The rest is the same as in Example 1

[0084] Comparative Example 4

[0085] Component B includes the following components in percentage by mass (accounting for component B): 80% of curing agent oxalic acid-modified isophorone diamine and 20% of Mannich base-modified diethylene triamine.

[0086] The rest is the same as in Example 1

[0087] The coating of the present invention was subjected to performance testing after being completely cured. The main performance index testing methods are shown in Table 1. The test results of Examples 1-5 of the present invention and Comparative Examples 1-4 are shown in Table 2.

[0088] Table 1 Main performance indicators and detection methods used in the present invention

[0089]

[0090] Table 2 Test results of Examples 1-5 of the present invention and Comparative Examples 1-4

[0091]

[0092]

[0093] In the test, “intact” is judged as “no blistering, no peeling, no rust and no cracking of the coating”.

[0094] In summary, due to the introduction of different groups (such as phenolic or ketone groups) into the molecular structure of Mannich base modified amine, it can give the cured epoxy resin better flexibility than traditional amine curing agents. This enables the cured product to better resist external impact and reduce the possibility of cracking. The carboxylic acid group can participate in the curing reaction to form a more stable chemical bond, enhancing the resistance of the cured product to chemicals such as acids and alkalis.

[0095] Different ratios can lead to very different properties of the cured product. For example, if the proportion of Mannich base modified amine epoxy curing agent is too high, the cured product may be too soft, while if the proportion of carboxylic acid modified amine curing agent is too high, the curing speed may be too slow. It can be seen that Mannich base modified amine epoxy curing agent provides fast curing characteristics, while carboxylic acid modified amine curing agent can slightly moderate the curing speed to a certain extent, avoiding problems such as internal stress caused by too fast curing.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A solvent-free epoxy coating, characterized in that: The coating comprises component A and component B. Component A includes bisphenol A epoxy resin, active diluent, leveling agent, defoaming agent and anti-settling agent; Component B includes curing agents oxalic acid-modified isophorone diamine and Mannich base-modified diethylene triamine.

2. The solvent-free epoxy coating according to claim 1, characterized in that: Component A includes the following raw materials in parts by weight: 40-50 parts of bisphenol A epoxy resin, 5-10 parts of active diluent, 0.1-0.5 parts of leveling agent, 0.1-0.5 parts of defoaming agent, and 0.2-0.5 parts of anti-settling agent; The second component comprises the following raw materials in parts by weight: 60-70 parts by weight of curing agent oxalic acid-modified isophorone diamine and Mannich base-modified diethylene triamine.

3. The solvent-free epoxy coating according to claim 2, characterized in that: Component A includes the following raw materials in parts by weight: 42-48 parts of bisphenol A epoxy resin, 7-9 parts of active diluent, 0.2-0.4 parts of leveling agent, 0.2-0.4 parts of defoaming agent, and 0.3-0.5 parts of anti-settling agent; The second component comprises the following raw materials in parts by weight: curing agent oxalic acid modified isophorone diamine and Mannich base modified diethylene triamine, with a total weight of 62-70 parts.

4. The solvent-free epoxy coating according to claim 3, characterized in that: Component A includes the following raw materials in parts by weight: 45 parts of bisphenol A epoxy resin, 8 parts of reactive diluent, 0.3 parts of leveling agent, 0.3 parts of defoaming agent, and 0.5 parts of anti-settling agent; Component B includes the following raw materials in parts by weight: 70 parts by weight of oxalic acid-modified isophorone diamine and Mannich base-modified diethylenetriamine curing agent.

5. The solvent-free epoxy coating according to claim 2, characterized in that: The curing agent includes 30-35 parts of oxalic acid-modified isophorone diamine and 30-35 parts of Mannich base-modified diethylene triamine.

6. The solvent-free epoxy coating according to claim 1, characterized in that: The bisphenol A epoxy resin is one or both of bisphenol A epoxy resin 128 and E51; The active diluent is one or both of 1,4-butanediol diglycidyl ether and neopentyl glycol diglycidyl ether; The defoamer is one or both of defoamer A530 and defoamer 088; The leveling agent is one or more of leveling agent BYK-320, leveling agent BYK-333 and leveling agent EFKA 3772; The anti-settling agent is organic bentonite BS-1C.

7. The solvent-free epoxy coating according to claim 1, characterized in that: The preparation method of the oxalic acid-modified isophorone diamine is as follows: Isophorone diamine and solvent xylene are added into a container, stirred, then oxalic acid is added, and then toluene sulfonic acid is added as a catalyst; the reaction system is slowly heated to 100-180°C, stirred at the reaction temperature, and reacted for 4-12 hours; samples are taken at regular intervals, and the changes in the acid value or amine value are determined by acid-base titration. When the changes in the acid value and the amine value are not obvious, the reaction is completed; the solvent in the reaction system is removed by reduced pressure distillation, and finally dried at 40-60°C for 12-24 hours to obtain an oxalic acid-modified isophorone diamine product.

8. The solvent-free epoxy coating according to claim 1, characterized in that: The preparation method of the Mannich base modified diethylenetriamine is: The method comprises taking benzaldehyde, diethylenetriamine and phenol as raw materials, using hydrochloric acid as a catalyst, carrying out the reaction in an ethanol solution, the reaction temperature being 50-100°C, and the reaction time being 2-8 hours; after the reaction is completed, removing the solvent by reduced pressure distillation to obtain a crude product; the crude product can be dissolved in ethanol, filtered to remove insoluble impurities, and then cooled for crystallization, filtered, and dried to obtain a Mannich base-modified diethylenetriamine product.

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