Anti-aging epoxy composite coating and preparation method thereof

Abstract

The invention relates to the field of coatings, and particularly discloses an anti-aging epoxy composite coating as well as a preparation method and application thereof. The invention relates to an anti-aging epoxy composite coating. The anti-aging epoxy composite coating is prepared from 0.8 mol to 1.2 mol of vinyl triethoxy silane, 0.8 mol to 1.2 mol of dimethyl diethoxy silane, 0.2 mol to 0.6 mol of phenyl triethoxy silane, 0.01 mol to 0.03 mol of dibutyltin dilaurate and 1.15 mol to 1.23 mol of a modified epoxy resin solution, wherein a polar functional group is introduced into the modified epoxy resin solution; the preparation method of the anti-aging epoxy composite coating comprises the step of carrying out copolymerization reaction on a modified epoxy resin solution grafted with acrylate and an organic silicon resin prepolymer to obtain the anti-aging epoxy composite coating. The epoxy composite coating provided by the invention has excellent anti-aging performance.

Description

Technical Field

[0001] The present application relates to the field of coatings, and more specifically, to an anti-aging epoxy composite coating and a preparation method thereof. Background Art

[0002] Epoxy resin is a polymer compound containing two or more epoxy groups. It can react with a curing agent to form a three-dimensional network structure with thermosetting properties. Cured epoxy resin has excellent mechanical, chemical and corrosion resistance, good thermal, adhesive and electrical properties, low shrinkage and stable dimensions after curing. Thanks to its excellent comprehensive performance, epoxy resin is widely used in coatings, adhesives, electronic product packaging, printed circuit boards, aviation, aerospace, military industry and other fields.

[0003] Epoxy resin is the base material of epoxy composite coating. However, epoxy composite coating has poor weather resistance during use, especially under ultraviolet rays, it will age and fail, which is manifested in surface yellowing, loss of gloss, cracks, etc., thus affecting its service life. In order to provide epoxy resin with anti-aging properties, epoxy resin monomers are usually copolymerized with monomers that can resist ultraviolet rays.

[0004] Although copolymerization modification of epoxy resin monomers with monomers that can resist ultraviolet rays can improve the aging resistance of epoxy composite coatings to a certain extent, during the copolymerization modification process, the polar functional groups on the epoxy resin monomers will participate in the reaction as reaction sites, and the resulting copolymers contain fewer polar functional groups. However, the reduction in the number of polar functional groups may affect the aging resistance of epoxy composite coatings. Summary of the invention

[0005] In order to improve the defect that the anti-aging performance of epoxy composite coatings is still insufficient, the present application provides an anti-aging epoxy composite coating and a preparation method thereof.

[0006] In the first aspect, the present application provides an anti-aging epoxy composite coating, which adopts the following technical solution:

[0007] An anti-aging epoxy composite coating and a preparation method thereof, comprising the following raw materials: comprising the following raw materials: 0.8-1.2 mol vinyl triethoxysilane, 0.8-1.2 mol dimethyl diethoxysilane, 0.2-0.6 mol monophenyl triethoxysilane, 0.01-0.03 mol dibutyltin dilaurate and 1.15-1.23 mol modified epoxy resin solution, wherein the modified epoxy resin solution is introduced with polar functional groups.

[0008] Since the vinyl group of vinyltriethoxysilane has good reactivity, the methyl group of dimethyldiethoxysilane has good heat resistance and hydrophobicity, and the phenyl group of monophenyltriethoxysilane has good UV resistance and chemical stability, they work together to form a cross-linked network structure with good weather resistance and environmental resistance.

[0009] However, when the monomers obtained from vinyl triethoxysilane, dimethyl diethoxy silane and monophenyl triethoxy silane as raw materials are copolymerized with epoxy resin monomers, the epoxy groups may participate in the ring-opening reaction and form new chemical bonds with the monomers obtained from vinyl triethoxy silane, dimethyl diethoxy silane and monophenyl triethoxy silane as raw materials, thereby consuming the original epoxy functional groups, thus resulting in a decrease in the number of polar functional groups. Since the modified epoxy resin solution used in the present application introduces polar functional groups, the polar functional groups that are reduced when the epoxy groups are copolymerized with the monomers obtained from vinyl triethoxy silane, dimethyl diethoxy silane and monophenyl triethoxy silane as raw materials can be compensated by the polar functional groups introduced by the modified epoxy resin solution, thereby not easily affecting the anti-aging properties of the epoxy composite coating.

[0010] Preferably, the modified epoxy resin solution contains acrylate, the modified epoxy resin solution is an acrylate-grafted epoxy resin solution, and the polar functional group is a hydroxyl functional group.

[0011] After the polar functional groups are introduced into the modified epoxy resin solution, its performance can be further improved, its adhesion to specific substrates can be enhanced, the compatibility of the resin with other resins can be improved, and the heat resistance and chemical resistance of the material can be improved.

[0012] Acrylates can improve the adhesion, weather resistance and UV resistance of the coating, while enhancing its mechanical strength and flexibility, making epoxy resin more suitable for outdoor and harsh environment applications. By grafting acrylates with epoxy resins, the polar functional groups introduced are hydroxyl functional groups, making the modified epoxy resin solution exhibit excellent performance in anti-aging, because it can effectively absorb ultraviolet rays and enhance the weather resistance of the material. At the same time, the presence of hydroxyl functional groups improves the antioxidant capacity of the modified epoxy resin solution, thereby significantly improving the stability and durability of the coating under long-term exposure to light, heat and environmental factors.

[0013] Preferably, the modified epoxy resin solution comprises the following raw materials: epoxy resin, benzoyl peroxide and xylene.

[0014] Since benzoyl peroxide acts as an initiator, it can trigger the grafting reaction of epoxy resin and acrylate, so that acrylate segments are introduced into the epoxy resin molecular chain, and then hydroxyl polar functional groups are introduced. Xylene acts as a solvent, which helps to dissolve the epoxy resin and other reactants, improve the uniformity of the reactants and the reaction efficiency. The introduction of acrylate segments can also absorb ultraviolet rays, reduce the degradation of the coating due to ultraviolet radiation, and improve the aging resistance.

[0015] Preferably, the epoxy resin is 0.2-0.3 mol, the benzoyl peroxide is 0.01-0.03 mol, and the xylene is 0.32-0.38 mol.

[0016] Since an appropriate amount of benzoyl peroxide can ensure that the epoxy resin is cured within an appropriate time, the curing rate is not easy to be too fast or too slow, and the production efficiency is improved. An appropriate amount of xylene helps to evenly mix the epoxy resin and benzoyl peroxide, so that the curing reaction is more uniform, and the risk of incomplete curing or local over-curing is reduced. Benzoyl peroxide as an initiator can effectively initiate the curing reaction of the epoxy resin, and xylene as a solvent can fully dissolve the reactants and provide a suitable reaction environment.

[0017] Preferably, the preparation method of the modified epoxy resin solution is as follows: 0.2-0.3 mol of epoxy resin is weighed and added into a four-necked flask, 0.06-0.1 mol of a xylene solution containing a mixed acrylate monomer is added, and then 0.01-0.03 mol of benzoyl peroxide is added, stirring is started to fully mix the materials, and the temperature is raised to 80° C. under the protection of nitrogen. After the reaction is kept warm for 30 minutes, 0.15-0.19 mol of a xylene solution of a mixed acrylate monomer is evenly added dropwise, and the addition is controlled to be completed within 1.5 hours. After the monomer addition is completed, the reaction is continued at 70-90° C. for 3 hours, and then cooled to room temperature, sealed and stored to obtain a modified epoxy resin solution.

[0018] Preferably, the acrylic ester mixed monomer includes two of hydroxypropyl acrylate, methyl methacrylate and glycidyl methacrylate.

[0019] Since hydroxypropyl acrylate and methyl methacrylate can absorb ultraviolet rays, they can reduce direct exposure to and damage to the coating, thereby improving the durability of the coating in outdoor environments. Both hydroxypropyl acrylate and methyl methacrylate have low absorption, thereby reducing material aging caused by moisture. Since glycidyl methacrylate contains epoxy groups, it can react with other functional groups such as hydroxyl, carboxyl or amino groups to form a cross-linked structure. This cross-linking effect can reduce the porosity of the coating, thereby reducing the permeability of water molecules, thereby improving the water barrier properties of the coating.

[0020] Preferably, the acrylic ester mixed monomer specifically includes hydroxypropyl acrylate and methyl methacrylate.

[0021] Preferably, the hydroxypropyl acrylate is 0.03-0.07 mol, and the methyl methacrylate is 0.22-0.28 mol.

[0022] In a second aspect, the present application provides a method for preparing an anti-aging epoxy composite coating, which adopts the following technical solution:

[0023] A method for preparing an anti-aging epoxy composite coating comprises the following steps:

[0024] S1: Weigh vinyl triethoxysilane, dimethyl diethoxysilane, monophenyl triethoxysilane and a catalyst into a four-necked flask, start stirring and heating, heat to the set reaction temperature, add distilled water dropwise under stirring, control the stability of the reaction temperature, and after the deionized water is added dropwise, continue to maintain the temperature until the reaction time. After the synthesis reaction, start reduced pressure distillation to evaporate the small molecule water and alcohol produced during the reaction to obtain a silicone resin prepolymer;

[0025] S2: Add the modified epoxy resin solution and the silicone resin prepolymer into a four-necked flask, and add the catalyst dibutyltin dilaurate, heat it with a heating jacket, raise the temperature to a certain temperature while stirring, and then keep the temperature constant for a certain period of time, and stop the reaction.

[0026] 1. Since the vinyl group of vinyltriethoxysilane has good reactivity, the methyl group of dimethyldiethoxysilane has good heat resistance and hydrophobicity, and the phenyl group of monophenyltriethoxysilane has good UV resistance and chemical stability, they work together to form a cross-linked network structure with good weather resistance and environmental resistance.

[0027] However, when the monomers obtained from vinyl triethoxysilane, dimethyl diethoxy silane and monophenyl triethoxy silane as raw materials are copolymerized with epoxy resin monomers, the epoxy groups may participate in the ring-opening reaction and form new chemical bonds with the monomers obtained from vinyl triethoxy silane, dimethyl diethoxy silane and monophenyl triethoxy silane as raw materials, thereby consuming the original epoxy functional groups, thus resulting in a decrease in the number of polar functional groups. Since the modified epoxy resin solution used in the present application introduces polar functional groups, the polar functional groups that are reduced when the epoxy groups are copolymerized with the monomers obtained from vinyl triethoxy silane, dimethyl diethoxy silane and monophenyl triethoxy silane as raw materials can be compensated by the polar functional groups introduced by the modified epoxy resin solution, thereby not easily affecting the anti-aging properties of the epoxy composite coating.

[0028] 2. Although the introduction of polar functional groups into the modified epoxy resin solution can further improve its performance, enhance its adhesion to specific substrates, improve the compatibility of the resin with other resins, and improve the heat resistance and chemical resistance of the material.

[0029] Acrylates can improve the adhesion, weather resistance and UV resistance of the coating, while enhancing its mechanical strength and flexibility, making epoxy resin more suitable for outdoor and harsh environment applications. By grafting acrylates with epoxy resins, the polar functional groups introduced are hydroxyl functional groups, making the modified epoxy resin solution exhibit excellent anti-aging performance because it can effectively absorb ultraviolet rays and enhance the weather resistance of the material. At the same time, the presence of hydroxyl functional groups improves the antioxidant capacity of the modified epoxy resin solution, thereby significantly improving the stability and durability of the coating under long-term exposure to light, heat and environmental factors.

[0030] 3. Since benzoyl peroxide acts as an initiator, it can trigger the grafting reaction of epoxy resin and acrylate, so that acrylate segments are introduced into the epoxy resin molecular chain, and then hydroxyl polar functional groups are introduced. Xylene acts as a solvent, which helps to dissolve the epoxy resin and other reactants, improve the uniformity of the reactants and the reaction efficiency. The introduction of acrylate segments can also absorb ultraviolet rays, reduce the degradation of the coating due to ultraviolet radiation, and improve the aging resistance. DETAILED DESCRIPTION

[0031] The present application is further described in detail below in conjunction with Examples 1-9 and Comparative Example 1.

[0032] raw material

[0033] Vinyltriethoxysilane CAS: 78-08-0; Dimethyldiethoxysilane CAS: 78-62-6; Monophenyltriethoxysilane CAS: 780-69-8; Dibutyltin dilaurate CAS: 77-58-7, Epoxy resin CAS: 61788-97-4; Xylene CAS: 1330-20-7; Hydroxypropyl acrylate CAS: 2918-23-2, Methyl methacrylate CAS: 80-62-6.

[0034] Example

[0035] Example 1

[0036] An anti-aging epoxy composite coating comprises the following raw materials: 1 mol of vinyl triethoxysilane, 1 mol of dimethyl diethoxysilane, 0.4 mol of monophenyl triethoxysilane, 0.02 mol of dibutyltin dilaurate and 1.19 mol of modified epoxy resin solution.

[0037] Specifically, the preparation method of the anti-aging epoxy composite coating comprises the following steps:

[0038] S1: Weigh 1 mol of vinyl triethoxysilane, 1 mol of dimethyl diethoxysilane, 0.4 mol of monophenyl triethoxysilane and 0.02 mol of catalyst dibutyltin dilaurate into a four-necked flask, start stirring and heating, heat to 90°C, add distilled water dropwise under stirring, control the stability of the reaction temperature, after the deionized water is added dropwise, react at a constant temperature for 4 hours, after the synthesis reaction, start reduced pressure distillation, evaporate the small molecular water and alcohol produced during the reaction, and obtain a silicone resin prepolymer;

[0039] S2: Weigh 0.25 mol of epoxy resin and add it into a four-necked flask, add 0.08 mol of xylene solution containing mixed acrylate monomers, wherein the xylene solution containing mixed acrylate monomers includes 0.05 mol of hydroxypropyl acrylate, 0.25 mol of methyl methacrylate and 0.35 mol of xylene, then add 0.02 mol of benzoyl peroxide, start stirring to mix the materials thoroughly, heat and raise the temperature to 80°C under the protection of nitrogen, keep the temperature for reaction for 30 minutes, then start to evenly add 0.17 mol of xylene solution of mixed acrylate monomers, and control the addition within 1.5 hours. After the monomers are added, continue to keep the temperature at 80°C for 3 hours, then cool to room temperature, seal and store, to obtain a modified epoxy resin solution.

[0040] S3: Add 1.19 mol of modified epoxy resin solution and 1 mol of silicone resin prepolymer into a four-necked flask, and add 0.02 mol of catalyst dibutyltin dilaurate, heat with a heating jacket, raise the temperature to 80° C. while stirring, then react at a constant temperature for 3 hours and stop the reaction.

[0041] Example 2-3

[0042] The difference from Example 1 is that the added amounts of the components of the anti-aging epoxy composite coating are different, as shown in Table 1.

[0043] Table 1 Addition amount of each component of the anti-aging epoxy composite coating in Examples 1-3 (mol)

[0044] Example 1 Example 2 Example 3 Vinyltriethoxysilane 1 0.8 1.2 Dimethyldiethoxysilane 1 1.2 0.8 Monophenyltriethoxysilane 0.4 0.6 0.2 Dibutyltin dilaurate 0.02 0.01 0.03 Modified epoxy resin solution 1.19 1.15 1.23

[0045] Example 4

[0046] The difference from Example 1 is that methyl methacrylate is replaced by glycidyl methacrylate.

[0047] Example 5

[0048] The difference from Example 1 is that the acrylate mixed monomer only includes hydroxypropyl acrylate.

[0049] Embodiment 6-7

[0050] The difference from Example 1 is that the added amounts of the components in the acrylic ester mixed monomer are different, as shown in Table 2.

[0051] Table 2 Addition amount of each component in the acrylic ester mixed monomer in Example 1 and Examples 6-7 (mol)

[0052]

[0053]

[0054] Embodiment 8-9

[0055] The difference from Example 1 is that the added amounts of the components in the modified epoxy resin solution are different, as shown in Table 3.

[0056] Table 3 Addition amount of each component in the modified epoxy resin solution in Example 1 and Examples 8-9 (mol)

[0057] Example 1 Example 8 Example 9 Epoxy resin 0.25 0.2 0.3 Benzoyl peroxide 0.02 0.01 0.03 Xylene 0.35 0.38 0.32

[0058] Comparative Example

[0059] Comparative Example 1

[0060] The difference from Example 1 is that the modified epoxy resin solution is replaced with the same amount of epoxy resin added.

[0061] Performance testing

[0062] Detection Methods

[0063] 1. Anti-ultraviolet performance test

[0064] Three samples were taken out from Examples 1-9 and Comparative Example 1, respectively, and Q235 carbon steel was selected as the substrate with a size of 80mm×50mm×1mm. After being polished with 360, 800, and 1200 mesh SiC sandpaper, they were cleaned with alcohol and acetone in turn, and placed in an oven and baked at 80°C for 3 hours. The baked Q235 carbon steel was immersed in the above samples respectively, and pulled out at a speed of 20cm / min after 2 minutes. This was repeated twice and dried at 80°C for 3 hours to obtain a composite coating with a thickness of (50±2)μm. The coating sample was then placed in a UV aging test box, and the light temperature was set to 60°C, the time was set to 12 hours, and the total time was set to 28 days (672 hours).

[0065] The test data are shown in Table 4.

[0066] Table 4 Anti-ultraviolet performance test table of Examples 1-9 and Comparative Example 1

[0067]

[0068] Combining Example 1 and Comparative Example 1 and Table 4, it can be seen that, relative to Example 1, although there is no change in the coating surface of Comparative Example 1 and Example 1 at 24h-168h, the coating surface of Comparative Example 1 begins to change from 336h, and the coating surface begins to change after 504h, until the coating surface completely changes color after 672h, while there is no change in the coating surface of Example 1 from 24h to 672h. This shows that, relative to the addition of conventional epoxy resin, the addition of modified epoxy resin solution can effectively improve the UV resistance of the epoxy composite coating, thereby improving the aging resistance of the epoxy composite coating.

[0069] The reason is that when conventional epoxy resins are copolymerized with monomers that can resist ultraviolet rays, the epoxy groups may participate in the ring-opening reaction and form new chemical bonds with the monomers that can resist ultraviolet rays, thereby consuming the original epoxy functional groups. As a result, the number of polar functional groups is reduced. The modified epoxy resin solution introduces hydroxyl functional groups through the acrylate mixed monomer, thereby increasing the number of polar functional groups.

[0070] Referring to Examples 1-3 and in combination with Table 4, it can be seen that, relative to Example 1, there is no obvious change in Example 2 and Example 3 at 672h, so the anti-ultraviolet performance is reduced, which shows that the addition amount of each component also affects the anti-ultraviolet performance of the epoxy composite coating.

[0071] Referring to Example 1 and Example 4 and combining with Table 4, it can be seen that, relative to Example 1, Example 4 has no obvious change at 504h, and the coating surface begins to change color at 672h, which shows that replacing methyl methacrylate in the acrylate mixed monomer will also affect the UV resistance of the epoxy composite coating to a certain extent.

[0072] Referring to Example 1 and Example 5 and combining with Table 4, it can be seen that, relative to Example 1, the coating surface of Example 5 began to show no obvious change at 336h, until the coating surface began to change color at 504h, and the coating surface showed obvious color change at 672h, which shows that the acrylate mixed monomer containing only hydroxypropyl acrylate will also affect the UV resistance of the epoxy composite coating.

[0073] Referring to Example 1 and Examples 6-7 and in combination with Table 4, it can be seen that, relative to Example 1, there is no significant change in Example 6 and Example 7 at 672 hours, which indicates that the addition amount of each component in the acrylate mixed monomer also affects the UV resistance of the epoxy composite coating.

[0074] Referring to Example 1 and Examples 8-9 and in combination with Table 4, it can be seen that, relative to Example 1, there is no significant change in Example 8 and Example 9 at 672 hours, which indicates that the addition amount of each component in the modified epoxy resin solution also affects the UV resistance of the epoxy composite coating.

[0075] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed. However, as long as it is within the scope of the claims of the present application, it shall be protected by the patent law.

Claims

1. An anti-aging epoxy composite coating, characterized in that: The invention comprises the following raw materials: 0.8-1.2 mol of vinyl triethoxysilane, 0.8-1.2 mol of dimethyl diethoxysilane, 0.2-0.6 mol of monophenyl triethoxysilane, 0.01-0.03 mol of dibutyltin dilaurate and 1.15-1.23 mol of modified epoxy resin solution, wherein polar functional groups are introduced into the modified epoxy resin solution.

2. The anti-aging epoxy composite coating according to claim 1, characterized in that: The modified epoxy resin solution contains acrylate, the modified epoxy resin solution is an acrylate-grafted epoxy resin solution, and the polar functional group is a hydroxyl functional group.

3. The anti-aging epoxy composite coating according to claim 2, characterized in that: The modified epoxy resin solution comprises the following raw materials: epoxy resin, benzoyl peroxide and xylene.

4. The anti-aging epoxy composite coating according to claim 3, characterized in that: The epoxy resin is 0.2-0.3 mol, the benzoyl peroxide is 0.01-0.03 mol, and the xylene is 0.32-0.38 mol.

5. The anti-aging epoxy composite coating according to claim 4, characterized in that: The preparation method of the modified epoxy resin solution comprises the following steps: weighing 0.2-0.3 mol of epoxy resin and adding it into a four-necked flask, adding 0.06-0.1 mol of a xylene solution containing a mixed acrylate monomer, and then adding 0.01-0.03 mol of benzoyl peroxide, stirring to fully mix the materials, heating to 80° C. under the protection of nitrogen, and keeping the temperature for reaction for 30 minutes, then uniformly dropping 0.15-0.19 mol of a xylene solution containing a mixed acrylate monomer, and controlling the addition to be completed within 1.5 hours. After the monomers are added, continuing to keep the temperature for reaction at 70-90° C. for 3 hours, cooling to room temperature, and sealing for storage to obtain the modified epoxy resin solution.

6. The anti-aging epoxy composite coating according to claim 5, characterized in that: The acrylic acid ester mixed monomer includes two of hydroxypropyl acrylate, methyl methacrylate and glycidyl methacrylate.

7. The anti-aging epoxy composite coating according to claim 6, characterized in that: The acrylic acid ester mixed monomer specifically includes hydroxypropyl acrylate and methyl methacrylate.

8. The anti-aging epoxy composite coating according to claim 7, characterized in that: The hydroxypropyl acrylate is 0.03-0.07 mol, and the methyl methacrylate is 0.22-0.28 mol.

9. The method for preparing an anti-aging epoxy composite coating according to any one of claims 1 to 8, characterized in that The following steps are involved: S1: Weigh 0.8-1.2 mol of vinyl triethoxysilane, 0.8-1.2 mol of dimethyl diethoxysilane, 0.2-0.6 mol of monophenyl triethoxysilane and 0.01-0.03 mol of catalyst dibutyltin dilaurate into a four-necked flask, start stirring and heating, heat to the set reaction temperature, add distilled water dropwise under stirring, control the stability of the reaction temperature, and after the deionized water is added dropwise, continue to maintain the temperature until the reaction time, after the synthesis reaction, start reduced pressure distillation, evaporate the small molecule water and alcohol produced during the reaction, and obtain the silicone resin prepolymer; S2: Add the modified epoxy resin solution and the silicone resin prepolymer into a four-necked flask, and add 0.01-0.03 mol of the catalyst dibutyltin dilaurate, heat with a heating jacket, raise the temperature to a certain temperature while stirring, and then react at a constant temperature for a certain period of time, and stop the reaction.

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