A kind of water-based acrylic waterproof coating and preparation method thereof

Abstract

The present invention relates to the field of coating technology, and in particular to a water-based acrylic waterproof coating and a preparation method thereof. The water-based acrylic waterproof coating is prepared from the following raw materials in parts by weight: 15-20 parts of water-based silicone oil acrylic emulsion, 50-65 parts of pure acrylic emulsion, 20-30 parts of filler, 5-9 parts of amino resin, 5-10 parts of film-forming aid, 3-5 parts of thickener, 0.3-1 parts of defoamer and 15-20 parts of deionized water. Among them, the water-based silicone oil acrylic emulsion is obtained by emulsion polymerization of silicone oil monomer, methyl methacrylate, methyl acrylate, hydroxyethyl methacrylate and styrene. The water-based acrylic waterproof coating provided by the present invention has excellent mechanical properties and waterproof properties, and most importantly, has high adhesion, high bonding strength, is not easy to bubble and crack, and is particularly suitable for outdoor environments.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, and in particular to a water-based acrylic waterproof coating and a preparation method thereof. Background Art

[0002] Acrylic resin paint is a high-performance polymer paint with good film-forming properties, adhesion and aging resistance. However, since acrylic resin molecules contain ester groups, the coating formed by them has a certain water permeability. Especially when exposed to sunlight, wind, rain, and acidic substances, the ester groups are prone to hydrolysis, which reduces the performance of the coating. Therefore, the water resistance of acrylic resin is poor, which affects its further application in the coating field.

[0003] Silicone polymer is a semi-organic high molecular material. Its main chain is composed of silicon atoms and oxygen atoms, and has good hydrophobicity. The silicone polymer is chemically grafted to the acrylate molecule to obtain a grafted monomer, and then copolymerized with other acrylate monomers to introduce silicone into the polymer resin chain. The hydrophobic properties of the silicone polymer can be effectively combined with the acrylic resin, which not only retains its original excellent film-forming properties, mechanical strength, aging resistance, etc., but also greatly increases its elasticity, weather resistance, heat resistance, gloss retention, pigment powder resistance, stain resistance and low-temperature flexibility, making it a waterproof coating with excellent comprehensive performance.

[0004] The existing patent technology document CN202210779719.4 discloses a highly water-resistant water-based waterproof coating with flame retardancy and a preparation method thereof. The raw material composition of the highly water-resistant water-based waterproof coating includes: acrylic emulsion, filler, water, and flame retardant modifier; the flame retardant modifier is hydroxy silicone oil. The invention uses hydroxy silicone oil with a large number of active groups as a flame retardant modifier for water-based waterproof coatings, which can effectively improve the stability and safety of some existing waterproof coatings in high humidity and water environments, and maintain efficient waterproofing. However, a high content of hydroxy silicone oil not only increases the cost of the coating, but also due to the softness of the silicon chain, it will reduce the adhesion of the coating, reduce the bonding strength, and make it easy to bubble and crack. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a water-based acrylic waterproof coating and a preparation method thereof to solve the problem of poor water resistance of acrylic resin.

[0006] Based on the above purpose, the present invention provides a water-based acrylic waterproof coating, which is prepared from the following raw materials in parts by weight: 15-20 parts of water-based silicone oil acrylic emulsion, 50-65 parts of pure acrylic emulsion, 20-30 parts of filler, 5-9 parts of amino resin, 5-10 parts of film-forming aid, 3-5 parts of thickener, 0.3-1 part of defoamer and 15-20 parts of deionized water.

[0007] Further, the preparation method of the water-based silicone oil acrylic emulsion is as follows:

[0008] S1: Mix hydroxyethyl acrylate, maleic anhydride and triethylamine, heat to 100-110°C and stir for 30-50 minutes, then add biphenyl anhydride and continue to react for 1-2 hours, finally add single-ended hydroxypropyl silicone oil and react until the acid value of the system is stable to obtain silicone oil monomer;

[0009] S2: mixing silicone oil monomer, methyl methacrylate, methyl acrylate, hydroxyethyl methacrylate, styrene, emulsifier and deionized water to obtain a pre-emulsion;

[0010] S3: Heat the pre-emulsion to 80-85°C, add potassium persulfate, and react for 3-4 hours to obtain a water-based silicone oil acrylic emulsion.

[0011] Furthermore, the molecular weight of the single-ended hydroxypropyl silicone oil in step S1 is 500;

[0012] Furthermore, in step S1, the weight ratio of hydroxyethyl acrylate, maleic anhydride, triethylamine, biphenyl anhydride and single-ended hydroxypropyl silicone oil is 1.2-2.4:0.2-0.5:0.03-0.05:1.8-3.2:4-8.

[0013] Furthermore, in step S2, the weight ratio of silicone oil monomer, methyl methacrylate, methyl acrylate, hydroxyethyl methacrylate, styrene, emulsifier and deionized water is 1-2:5-8:2-4:3-4:1-2:0.1-0.5:30-40.

[0014] Preferably, the emulsifier in step S2 is a mixture of polyoxyethylene octylphenol ether and sodium dodecyl sulfate.

[0015] Furthermore, the amount of potassium persulfate added in step S3 is 0.5-1% of the weight of the pre-emulsion.

[0016] Preferably, the pure acrylic emulsion has a solid content of 30-50% and a pH of 2-4.

[0017] Preferably, the filler is one of mica powder, talcum powder and heavy calcium carbonate powder.

[0018] Preferably, the amino resin is water-based melamine formaldehyde resin.

[0019] Preferably, the film-forming aid is one of propylene glycol butyl ether and dipropylene glycol butyl ether or a mixture of the two.

[0020] Preferably, the thickener is one of a polyurethane thickener and an acrylic thickener.

[0021] Preferably, the defoaming agent is a silicone defoaming agent.

[0022] Furthermore, the present invention also provides a method for preparing the above-mentioned water-based acrylic waterproof coating, comprising the following steps:

[0023] (1) mixing the water-based silicone oil acrylic emulsion and the pure acrylic emulsion to obtain a mixed emulsion;

[0024] (2) Add filler, amino resin, film-forming aid, thickener, defoamer and deionized water into the mixed emulsion, stir evenly, and obtain a water-based acrylic waterproof coating.

[0025] Beneficial effects of the present invention:

[0026] The present invention uses maleic anhydride and biphenyl anhydride as "bridges" to connect hydroxyethyl acrylate and single-end hydroxypropyl silicone oil, prepares silicone oil containing multiple double bonds at one end and a silicone oil monomer mixture containing double bonds and biphenyl at one end, copolymerizes the silicone oil with traditional acrylate monomers to form a water-based silicone oil acrylic emulsion, and further prepares a water-based acrylic waterproof coating. Through the coordinated regulation of maleic anhydride and biphenyl anhydride, the problem that organic silicon causes the coating to have reduced adhesion, reduced bonding strength, and easy bubbling and cracking is effectively solved, and the coating has a higher waterproof ability. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0028] In a specific embodiment of the present invention, the single-ended hydroxypropyl silicone oil was purchased from Shandong Yonglida New Material Technology Co., Ltd. with a molecular weight of 500; the pure acrylic emulsion was purchased from Hubei Xinrunde Chemical Co., Ltd. with a solid content of 40% and a pH of 3.2; the model of the amino resin is CYMEL385.

[0029] Embodiment 1:

[0030] (1) 1.2 g of hydroxyethyl acrylate, 0.2 g of maleic anhydride and 0.03 g of triethylamine were mixed, heated to 100° C. and stirred for 50 min, then 1.8 g of biphenyl anhydride was added and the reaction was continued for 1 h, and finally 4 g of single-end hydroxypropyl silicone oil was added and reacted until the acid value of the system was stable to obtain silicone oil monomer;

[0031] (2) 1 g of silicone oil monomer, 5 g of methyl methacrylate, 2 g of methyl acrylate, 3 g of hydroxyethyl methacrylate, 1 g of styrene, 0.03 g of polyoxyethylene octylphenol ether, 0.07 g of sodium lauryl sulfate and 30 g of deionized water were mixed to obtain a pre-emulsion;

[0032] (3) heating the pre-emulsion to 80° C., adding 0.12 g of potassium persulfate, and reacting for 3 h to obtain a water-based silicone oil acrylic emulsion;

[0033] (4) mixing 15 g of the aqueous silicone oil acrylic emulsion and 50 g of the pure acrylic emulsion to obtain a mixed emulsion;

[0034] (5) 20 g of mica powder, 5 g of amino resin, 5 g of propylene glycol butyl ether, 3 g of thickener BYK-425, 0.3 g of defoamer BYK-a525 and 15 g of deionized water were added to the mixed emulsion and stirred evenly to obtain a water-based acrylic waterproof coating.

[0035] Embodiment 2:

[0036] (1) 1.8 g of hydroxyethyl acrylate, 0.35 g of maleic anhydride and 0.04 g of triethylamine were mixed, heated to 100° C. and stirred for 40 min, then 2.5 g of biphenyl anhydride was added and the reaction was continued for 1.5 h, and finally 6 g of single-end hydroxypropyl silicone oil was added and the reaction was continued until the acid value of the system was stable to obtain silicone oil monomer;

[0037] (2) 1.5 g of silicone oil monomer, 7 g of methyl methacrylate, 3 g of methyl acrylate, 3.5 g of hydroxyethyl methacrylate, 1.5 g of styrene, 0.1 g of polyoxyethylene octylphenol ether, 0.2 g of sodium lauryl sulfate and 40 g of deionized water were mixed to obtain a pre-emulsion;

[0038] (3) heating the pre-emulsion to 85° C., adding 0.35 g of potassium persulfate, and reacting for 3 h to obtain a water-based silicone oil acrylic emulsion;

[0039] (4) 18 g of the aqueous silicone oil acrylic emulsion and 60 g of the pure acrylic emulsion were mixed to obtain a mixed emulsion;

[0040] (5) 27 g of mica powder, 7.5 g of amino resin, 8 g of propylene glycol butyl ether, 4.5 g of thickener BYK-425, 0.7 g of defoamer BYK-a525 and 18 g of deionized water were added to the mixed emulsion and stirred evenly to obtain a water-based acrylic waterproof coating.

[0041] Embodiment 3:

[0042] (1) 2.4 g of hydroxyethyl acrylate, 0.5 g of maleic anhydride and 0.05 g of triethylamine were mixed, heated to 110° C. and stirred for 30 min, then 3.2 g of biphenyl anhydride was added and the reaction was continued for 2 h, and finally 8 g of single-end hydroxypropyl silicone oil was added and reacted until the acid value of the system was stable to obtain silicone oil monomer;

[0043] (2) 2 g of silicone oil monomer, 8 g of methyl methacrylate, 4 g of methyl acrylate, 4 g of hydroxyethyl methacrylate, 2 g of styrene, 0.2 g of polyoxyethylene octylphenol ether, 0.3 g of sodium lauryl sulfate and 40 g of deionized water were mixed to obtain a pre-emulsion;

[0044] (3) heating the pre-emulsion to 85° C., adding 0.6 g of potassium persulfate, and reacting for 3 h to obtain a water-based silicone oil acrylic emulsion;

[0045] (4) 20 g of the aqueous silicone oil acrylic emulsion and 65 g of the pure acrylic emulsion were mixed to obtain a mixed emulsion;

[0046] (5) 30 g of talc, 9 g of amino resin, 10 g of propylene glycol butyl ether, 5 g of thickener BYK-425, 1 g of defoamer BYK-a525 and 20 g of deionized water were added to the mixed emulsion and stirred evenly to obtain a water-based acrylic waterproof coating.

[0047] Comparative Example 1:

[0048] 1.8 g of hydroxyethyl acrylate, 0.35 g of maleic anhydride and 0.04 g of triethylamine were mixed, heated to 100°C and stirred for 40 min, then 2.5 g of maleic anhydride was added and the reaction was continued for 1.5 h, and finally 6 g of single-end hydroxypropyl silicone oil was added and the reaction was continued until the acid value of the system was stable to obtain silicone oil monomer;

[0049] The remaining steps are the same as those in Example 2 and will not be described in detail here.

[0050] Comparative Example 2:

[0051] 1.8 g of hydroxyethyl acrylate, 0.35 g of biphenyl anhydride and 0.04 g of triethylamine were mixed, heated to 100°C and stirred for 40 min, then 2.5 g of biphenyl anhydride was added and the reaction was continued for 1.5 h, and finally 6 g of single-end hydroxypropyl silicone oil was added and the reaction was continued until the acid value of the system was stable to obtain silicone oil monomer;

[0052] The remaining steps are the same as those in Example 2 and will not be described in detail here.

[0053] Comparative Example 3:

[0054] 1.5 g of single-end hydroxypropyl silicone oil, 7 g of methyl methacrylate, 3 g of methyl acrylate, 3.5 g of hydroxyethyl methacrylate, 1.5 g of styrene, 0.1 g of polyoxyethylene octylphenol ether, 0.2 g of sodium lauryl sulfate and 40 g of deionized water were mixed to obtain a pre-emulsion;

[0055] The remaining steps are the same as those in Example 2 and will not be described in detail here.

[0056] Performance Test:

[0057] Preparation of cured film: The coatings obtained in the examples and comparative examples were evenly scraped onto the surface of the polished tinplate sheet and cured at 180° C. for 10 min to obtain the corresponding coatings.

[0058] Mechanical properties: The cured film was subjected to a tensile test using an electronic universal testing machine at a tensile rate of 10 mm / min. Five measurements were performed for each group to ensure the accuracy of the data, and the average values ​​were calculated to obtain the tensile strength and elongation at break of the cured film. The results are shown in Table 1.

[0059] Adhesion test: The cured film was tested using a fully automatic pull-off adhesion tester with a measuring range of 0.7-20 MPa. The results are shown in Table 1.

[0060] Water contact angle test: The water contact angle of the cured film surface was measured by the sessile drop method. The results are shown in Table 1.

[0061] Table 1 Performance test results

[0062]

[0063]

[0064] Data Analysis:

[0065] It can be seen from Examples 1-3 that the water-based acrylic waterproof coating prepared by the present invention has excellent mechanical properties after film formation, and its tensile strength can reach 2.34 MPa, and has excellent waterproof performance. Most importantly, it has high adhesion and bonding strength, is not easy to bubble and crack, and is particularly suitable for outdoor environments.

[0066] It can be seen from Example 2 and Comparative Examples 1-2 that maleic anhydride and biphenyl anhydride synergistically promote the adhesion of the coating. This is mainly because the olefin groups on the maleic anhydride increase the crosslinking density, while the biphenyl groups on the biphenyl anhydride have the function of releasing internal stress by intramolecular rotation. The matching use of the two synergistically improves the bonding strength between the coating and the substrate, reduces the tiny gap between the coating and the substrate after film formation, and thus improves the adhesion.

[0067] It can be seen from Example 2 and Comparative Example 3 that, compared with directly adding single-end hydroxypropyl silicone oil to acrylic emulsion, the aqueous silicone oil acrylic emulsion prepared using the silicone oil monomer prepared by the present invention can effectively improve the mechanical properties and adhesion of the coating after film formation, while maintaining a high water resistance, which is mainly due to the higher cross-linking density, effective internal stress release and the hydrophobicity of the silicone pendant on the acrylic chain.

[0068] The specific performance of Example 2 is compared with the indicators of the exposed acrylic waterproof coating as shown in Table 2.

[0069] Table 2 Performance comparison

[0070]

[0071]

[0072] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

Claims

1. A water-based acrylic waterproof coating, characterized in that: The method is prepared from the following raw materials in parts by weight: 15-20 parts of water-based silicone oil acrylic emulsion, 50-65 parts of pure acrylic emulsion, 20-30 parts of filler, 5-9 parts of amino resin, 5-10 parts of film-forming aid, 3-5 parts of thickener, 0.3-1 part of defoamer and 15-20 parts of deionized water; The preparation method of the aqueous silicone oil acrylic emulsion is as follows: S1: Mix hydroxyethyl acrylate, maleic anhydride and triethylamine, heat to 100-110°C and stir for 30-50 minutes, then add biphenyl anhydride and continue to react for 1-2 hours, finally add single-ended hydroxypropyl silicone oil and react until the acid value of the system is stable to obtain silicone oil monomer; S2: mixing silicone oil monomer, methyl methacrylate, methyl acrylate, hydroxyethyl methacrylate, styrene, an emulsifier and deionized water to obtain a pre-emulsion; S3: heating the pre-emulsion to 80-85°C, adding potassium persulfate, and reacting for 3-4 hours to obtain a water-based silicone oil acrylic emulsion; The molecular weight of the single-ended hydroxypropyl silicone oil in step S1 is 500; In step S1, the weight ratio of hydroxyethyl acrylate, maleic anhydride, triethylamine, biphenyl anhydride and single-ended hydroxypropyl silicone oil is 1.2-2.4:0.2-0.5:0.03-0.05:1.8-3.2:4-8; In the step S2, the weight ratio of silicone oil monomer, methyl methacrylate, methyl acrylate, hydroxyethyl methacrylate, styrene, emulsifier and deionized water is 1-2:5-8:2-4:3-4:1-2:0.1-0.5:30-40; The amount of potassium persulfate added in step S3 is 0.5-1% of the weight of the pre-emulsion.

2. The water-based acrylic waterproof coating according to claim 1, characterized in that: The pure acrylic emulsion has a solid content of 30-50% and a pH of 2-4.

3. The water-based acrylic waterproof coating according to claim 1, characterized in that: The filler is one of mica powder, talcum powder and heavy calcium carbonate powder.

4. The water-based acrylic waterproof coating according to claim 1, characterized in that: The amino resin is water-based melamine formaldehyde resin.

5. The water-based acrylic waterproof coating according to claim 1, characterized in that: The film-forming aid is one of propylene glycol butyl ether and dipropylene glycol butyl ether or a mixture of the two.

6. The water-based acrylic waterproof coating according to claim 1, characterized in that: The thickener is one of a polyurethane thickener and an acrylic thickener.

7. The water-based acrylic waterproof coating according to claim 1, characterized in that: The defoaming agent is a silicone defoaming agent.

8. The water-based acrylic waterproof coating according to claim 1, characterized in that: The emulsifier in step S2 is a mixture of polyoxyethylene octylphenol ether and sodium lauryl sulfate.

9. A method for preparing a water-based acrylic waterproof coating according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) mixing water-based silicone oil acrylic emulsion and pure acrylic emulsion to obtain a mixed emulsion; (2) Add filler, amino resin, film-forming aid, thickener, defoamer and deionized water into the mixed emulsion, stir evenly, and obtain a water-based acrylic waterproof coating.

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