A chemically resistant, easy-to-clean silicone-modified acrylic adhesive and its preparation method

Abstract

This application relates to the technical field of adhesives, and more specifically, to a chemically resistant, easy-to-clean silicone-modified acrylic adhesive and its preparation method. It comprises methacryloyloxyacrylate monomer, acryloyloxyacrylate monomer, unsaturated organosilane, branched hydroxyl polyester, nanofiller, initiator, and reactive diluent; the methacryloyloxyacrylate monomer is 2-methacryloyloxyethyl phthalate and / or mono-2-(methacryloyloxy)ethyl maleate; the acryloyloxyacryloyloxyacrylate monomer is one or more of 9,9-bis[4-(2-acryloyloxyethoxy)phenyl], ethoxylated bisphenol A diacrylate, and 2-phenoxyethyl acrylate. All of the above are solvent-free, environmentally friendly, and fluorine-free, and their interactions create a synergistic effect, further improving the chemical resistance and easy-to-clean properties of the cured silicone-modified acrylic adhesive.

Description

Technical Field

[0001] This application relates to the technical field of adhesives, and more specifically, to a chemically resistant, easy-to-clean silicone-modified acrylic adhesive and its preparation method. Background Art

[0002] With the advancement of technology, various electronic products are developing rapidly, especially in fields such as new energy vehicles and drones, where the requirements for materials are becoming increasingly stringent. These applications not only require high-performance electronic equipment but also reliable connection and fixing materials to ensure product safety and stability. For example, in new energy power battery packs, the fixing, sealing, and potting of individual battery cells are critical steps; in drones, the connection and fixing of components such as wings, tail fins, and fuselages are also essential. Furthermore, the fixing and sealing of electronic components such as circuit boards, sensors, and batteries also require highly efficient and stable adhesives to provide protection and prevent damage caused by vibration or impact.

[0003] To meet these requirements, existing technologies primarily employ silicone-modified acrylic adhesives. These adhesives combine the advantages of both silicone and acrylic, exhibiting excellent weather resistance, aging resistance, high bond strength, and good flexibility. This improves the stable fixation and sealing of various structures in new energy batteries and drones, thereby enhancing their structural stability.

[0004] However, when silicone-modified acrylic adhesives are used for sealing and structural connections of agricultural drones, agricultural drones are typically used for crop monitoring and pesticide application. In particular, during long-term use, pesticides and other chemicals can easily corrode the connection or sealing structures formed by the drones. Furthermore, the adhesive surface easily absorbs dirt, making cleaning difficult. Over time, this affects structural stability, which not only affects the product's appearance but may also reduce its lifespan and safety.

[0005] To address the aforementioned issues, current methods include introducing fluorinated reactive monomers. However, these monomers may generate fluoride pollution during production and use, posing a potential threat to the environment and ecosystems. Therefore, developing an environmentally friendly, chemically resistant, and easy-to-clean silicone-modified acrylic adhesive has become an urgent technical challenge. Summary of the Invention

[0006] In order to reduce pollution to the ecological environment and obtain a silicone-modified acrylic adhesive with better corrosion resistance and pollution resistance, especially against chemical substances such as pesticides, this application provides a chemically resistant and easy-to-clean silicone-modified acrylic adhesive and its preparation method.

[0007] In a first aspect, this application provides a chemically resistant, easy-to-clean silicone-modified acrylic adhesive, composed of the following raw materials by weight percentage:

[0008] Methacryloxyacrylate monomer: 38-60%;

[0009] Acryloyloxyacrylate monomer: 5-20%;

[0010] Unsaturated organosilanes: 9-22%;

[0011] Branched hydroxyl polyester: 0.1-2%;

[0012] Nanofiller: 1-5%;

[0013] Initiator: 1-3%;

[0014] The remainder is reactive diluent;

[0015] The methacryloyloxy acrylate monomer is 2-methacryloyloxyethyl phthalate and / or mono-2-(methacryloyloxy)ethyl maleate.

[0016] The acryloyloxyacrylate monomer is one or more of 9,9-bis[4-(2-acryloyloxyethoxy)phenyl], ethoxylated bisphenol A diacrylate, and 2-phenoxyethyl acrylate.

[0017] By adopting the above technical solution, through the compounding of methacryloyloxyacrylate monomers and acryloyloxyacrylate monomers in a specific ratio, the adhesive exhibits excellent corrosion resistance and anti-fouling properties, especially against pesticides and other chemicals, as well as good cleanliness.

[0018] Branched hydroxyl polyesters exhibit excellent adhesion and cohesion, while also improving surface wettability, reducing stain adhesion, and increasing ease of cleaning. The synergistic effect of branched hydroxyl polyesters and acrylate monomers allows the branched hydroxyl polyester to impart good chemical resistance to the material, while methacryloxyacrylate monomers and acryloyloxyacrylate monomers enhance its chemical stability and adhesion. Therefore, the combination of these three components further improves the resistance of silicone-modified acrylic adhesives to pesticides and other chemicals after curing. Furthermore, the unsaturated organosilanes react further with methacryloxyacrylate monomers, acryloyloxyacrylate monomers, and branched hydroxyl polyesters to introduce siloxanes, further enhancing chemical corrosion resistance and stain resistance.

[0019] Nanofillers can fill the tiny pores on the surface of materials, improving the smoothness and flatness of the surface. At the same time, the hydrophobicity of unsaturated organosilanes can reduce the affinity between the material surface and water, and the synergistic effect of nanofillers and unsaturated organosilanes increases the difficulty of stain adhesion.

[0020] By adding an active diluent, the viscosity of the silicone-modified acrylic adhesive can be reduced, making it easier to pot and coat. Simultaneously, the diluent promotes uniform mixing between components, improves the homogeneity of the raw material system, and achieves better overall performance after the silicone-modified acrylic adhesive has fully cured. Furthermore, this application uses solvent-free adhesives and the formulation does not contain fluorine or other substances, thus providing greater environmental protection.

[0021] In summary, the components of this application, including methacryloyloxyacrylate monomer, acryloyloxyacrylate monomer, unsaturated organosilane, branched hydroxyl polyester, nanofiller, initiator, and reactive diluent, work together to enhance the cleaning and chemical corrosion resistance of the organosilicon-modified acrylic adhesive after it is used for structural connection or sealing of UAVs, especially its corrosion resistance and anti-pollution properties against chemicals such as pesticides.

[0022] Preferably, the acryloyloxyacrylate monomer is composed of 9,9-bis[4-(2-acryloyloxyethoxy)phenyl], ethoxylated bisphenol A diacrylate, and 2-phenoxyethyl acrylate in a weight ratio of 1:(1.5-3):(2-5).

[0023] By employing the above technical solution, the acryloyloxyacrylate monomer is compounded from 9,9-bis[4-(2-acryloyloxyethoxy)phenyl], ethoxylated bisphenol A diacrylate, and 2-phenoxyethyl acrylate in a specific weight ratio, resulting in adhesives with excellent chemical resistance and anti-fouling properties. The components in this combination work synergistically to improve the overall performance of the adhesive, particularly in its resistance to pesticides and other chemicals and its ability to reduce stain adhesion.

[0024] Preferably, the methacryloyloxy acrylate monomer is composed of 2-methacryloyloxyethyl phthalate and mono-2-(methacryloyloxy)ethyl maleate in a weight ratio of 1:(0.5-1.5).

[0025] By adopting the above technical solution, the methacryloyloxyacrylate monomer is composed of 2-methacryloyloxyethyl phthalate and / or mono-2-(methacryloyloxy)ethyl maleate in a weight ratio of 1:(0.5-1.5), which can effectively improve the chemical corrosion resistance and antifouling properties of the adhesive. This specific ratio of compounding makes the interaction between the two monomers more synergistic, thereby further improving the overall performance of the adhesive while ensuring good adhesion, especially in terms of pesticide corrosion resistance and antifouling properties.

[0026] Preferably, the unsaturated organosilane is methacrylate-terminated dimethyl polysiloxane and / or acrylate-cage-shaped polysilsesquioxane.

[0027] By employing the above-mentioned technical solutions, the addition of methacrylate-terminated dimethyl polysiloxane and / or acrylic-cage-type polysilsesquioxane significantly improves the chemical resistance and anti-fouling properties of the adhesive. The siloxane structure in these unsaturated organosilane molecules endows the adhesive with excellent hydrophobicity and surface smoothness, reducing the adhesion of contaminants and making the adhesive surface easier to clean. Simultaneously, these siloxane compounds also enhance the cohesive strength and mechanical properties of the adhesive, enabling it to maintain good bond strength and stability even in harsh environments.

[0028] Preferably, the unsaturated organosilane is composed of methacrylate-terminated dimethyl polysiloxane and acrylate-cage-shaped polysilsesquioxane in a weight ratio of (2-3):1.

[0029] By employing the above technical solution, a specific ratio of methacrylate-terminated dimethyl polysiloxane and acrylic-cage-shaped polysilsesquioxane significantly improves the chemical resistance and anti-fouling properties of the adhesive. Specifically, methacrylate-terminated dimethyl polysiloxane enhances the adhesive's water resistance and weather resistance, while acrylic-cage-shaped polysilsesquioxane improves the adhesive's mechanical properties and surface characteristics. Their synergistic effect allows the adhesive to maintain excellent stability and reliability even in complex environments.

[0030] Preferably, the nanofiller is PI powder and / or silicone powder.

[0031] In terms of ease of cleaning, PI powder and silicone powder have low surface energy and lubricity, making their adhesives smooth and less prone to contamination.

[0032] In terms of chemical corrosion resistance, both PI powder and silicone powder possess anti-corrosion properties. When used as nanofillers in adhesives, they can form a protective layer, effectively preventing the penetration of corrosive substances. Therefore, the addition of these nanofillers allows the adhesive to maintain good bonding performance while also possessing better chemical corrosion resistance and easy-to-clean properties. This improves the corrosion resistance of the adhesive, especially in harsh environments such as those containing pesticides, chemicals, and dust. Therefore, using the nanofillers of this application, in conjunction with other raw materials of this application, can achieve superior overall performance.

[0033] Preferably, the nanofiller is composed of PI and silicone powder in a weight ratio of (1-3):1.

[0034] By adopting the above technical solution, the nanofiller is composed of PI and silicone powder in a weight ratio of 1:(1-3), which further improves the mechanical strength and pesticide corrosion resistance of the adhesive, improves the surface smoothness of the adhesive, makes it easier to clean, and reduces corrosion and other phenomena that affect the stability of the structure after being used in agricultural drones.

[0035] PI powder is a polyimide powder, preferably from Evonik Industries, Germany. UHT.

[0036] Preferably, the initiator is composed of a photoinitiator and a thermal initiator.

[0037] By employing the above technical solutions, the combined use of photoinitiators and thermal initiators can significantly improve the curing speed and efficiency of adhesives, while ensuring the applicability and stability of adhesives under different environmental conditions. Photoinitiators can rapidly initiate polymerization reactions under light irradiation, making them suitable for applications requiring rapid curing; thermal initiators, on the other hand, can continue to function at high temperatures, ensuring effective curing of the adhesive under complex conditions and improving overall performance and reliability.

[0038] Preferably, the active diluent is epoxidized soybean oil.

[0039] By employing the above technical solution, epoxidized soybean oil, as an active diluent, can effectively reduce the viscosity of the system, improve processing performance, and simultaneously increase the curing speed and mechanical properties of the adhesive. These characteristics result in better application convenience and higher bond strength for this adhesive in practical applications.

[0040] Secondly, this application provides a method for preparing a chemically resistant, easy-to-clean silicone-modified acrylic adhesive, comprising the following steps:

[0041] According to the weight percentage, weigh out methacryloyloxyacrylate monomer, acryloyloxyacrylate monomer, unsaturated organosilane, branched hydroxyl polyester, nanofiller, initiator and reactive diluent, mix them evenly to obtain organosilicon modified acrylic adhesive.

[0042] By employing the above technical solution, this preparation method ensures that the components are accurately mixed in a specific ratio, thereby obtaining an organosilicon-modified acrylic adhesive with excellent chemical corrosion resistance and easy cleaning properties. When used in agricultural drones, it can reduce pesticide corrosion, and the adhesive surface that is not easily formed is less likely to be contaminated or adsorbed by pesticides, dust, etc., thus improving the durability and ease of cleaning of agricultural drones.

[0043] In summary, this application has the following beneficial effects:

[0044] 1. By using a specific ratio of methacryloyloxyacrylate monomer and acryloyloxyacrylate monomer, the chemical corrosion resistance and anti-pollution ability of the adhesive are significantly improved, effectively solving the problem that adhesives in the prior art are easily corroded by pesticides and other chemicals and adsorb dirt.

[0045] 2. The introduction of branched hydroxyl polyester enhances the adhesive's adhesion and cohesion, enabling it to form a strong bonding layer on various material surfaces. It also improves surface wettability, reduces stain adhesion, and enhances cleaning convenience.

[0046] 3. The addition of unsaturated organosilanes further enhances the adhesive's weather resistance and aging resistance, enabling it to maintain good performance even in harsh environments, thus extending the product's service life and safety. Detailed Implementation

[0047] The present application will be further described in detail below with reference to the embodiments.

[0048] Some of the raw materials:

[0049] Branched hydroxyl polyester Covestro 670;

[0050] Methacrylate mono-terminated dimethyl polysiloxane CAS No. 146632-07-7;

[0051] The PI powder and silicone powder used in this application are obtained by grinding, and their particle size is 100-500nm; the silicone powder brand and model is Yinyuan SR-402.

[0052] Epoxidized soybean oil.

[0053] Example

[0054] Example 1

[0055] The preparation of a chemically resistant, easy-to-clean silicone-modified acrylic adhesive includes the following steps:

[0056] Weigh out 38% methacryloyloxy acrylate monomer, 20% acryloyloxy acrylate monomer, 22% unsaturated organosilane, 0.1% branched hydroxyl polyester, 1% nanofiller, 3% initiator, and 15.9% reactive diluent by weight percentage and place them in a stirring device. Stir at 40 r / min for 10 min to ensure thorough mixing and obtain the organosilicon modified acrylic adhesive.

[0057] The methacryloyloxyacrylate monomer is 2-methacryloyloxyethyl phthalate; the acryloyloxyacrylate monomer is 2-phenoxyethyl acrylate; the unsaturated organosilane is methacrylate-terminated dimethyl polysiloxane; the nanofiller is PI powder; and the initiator is composed of photoinitiator 1301 and thermal initiator BPO in a weight ratio of 1:3. The reactive diluent is epoxidized soybean oil.

[0058] Example 2-3

[0059] The difference between Examples 2-3 and Example 1 is that the amount of raw materials used is different, as shown in Table 1.

[0060] Table 1. Raw material usage (%) for Examples 1-3

[0061]

[0062] Example 4

[0063] The difference between Example 4 and Example 1 is that the methacryloyloxy acrylate monomer is maleic acid mono-2-(methacryloyloxy)ethyl ester.

[0064] Example 5

[0065] The difference between Example 5 and Example 2 is that the methacryloyloxy acrylate monomer is composed of mono-2-(methacryloyloxy)ethyl maleate and 2-methacryloyloxyethyl phthalate in a weight ratio of 1:1.5.

[0066] Example 6

[0067] The difference between Example 6 and Example 2 is that the methacryloyloxy acrylate monomer is composed of mono-2-(methacryloyloxy)ethyl maleate and 2-methacryloyloxyethyl phthalate in a weight ratio of 1:0.5.

[0068] Example 7

[0069] The difference between Example 7 and Example 2 is that the acryloyloxyacrylate monomer is 9,9-bis[4-(2-acryloyloxyethoxy)phenyl].

[0070] Example 8

[0071] The difference between Example 8 and Example 2 is that the acryloyloxyacrylate monomer is ethoxylated bisphenol A diacrylate.

[0072] Example 9

[0073] The difference between Example 9 and Example 2 is that the acryloyloxyacrylate monomer is composed of 9,9-bis[4-(2-acryloyloxyethoxy)phenyl], ethoxylated bisphenol A diacrylate, and 2-phenoxyethyl acrylate in a weight ratio of 1:1:2.

[0074] Example 10

[0075] The difference between Example 10 and Example 5 is that the acryloyloxyacrylate monomer is composed of 9,9-bis[4-(2-acryloyloxyethoxy)phenyl], ethoxylated bisphenol A diacrylate, and 2-phenoxyethyl acrylate in a weight ratio of 1:1:2.

[0076] Example 11

[0077] The difference between Example 11 and Example 2 is that the unsaturated organosilane is an acrylic-cage-shaped polysilsesquioxane.

[0078] Example 12

[0079] The difference between Example 12 and Example 2 is that the unsaturated organosilane is composed of methacrylate-terminated dimethyl polysiloxane and acrylate-cage-shaped polysilsesquioxane in a weight ratio of 2:1.

[0080] Example 13

[0081] The difference between Example 13 and Example 10 is that the unsaturated organosilane is composed of methacrylate-terminated dimethyl polysiloxane and acrylate-cage-shaped polysilsesquioxane in a weight ratio of 2:1.

[0082] Example 14

[0083] The difference between Example 14 and Example 2 is that the nanofiller is PI powder.

[0084] Example 15

[0085] The difference between Example 15 and Example 2 is that the nanofiller is silicone powder.

[0086] Example 16

[0087] The difference between Example 16 and Example 2 is that the nanofiller is composed of PI powder and silicone powder in a weight ratio of 2:1.

[0088] Example 17

[0089] The difference between Example 17 and Example 13 is that the nanofiller is composed of PI powder and silicone powder in a weight ratio of 3:1.

[0090] Comparative Example

[0091] Comparative Example 1

[0092] The difference between Comparative Example 1 and Example 2 is that the methacryloyloxyacrylate monomer was replaced with an equal amount of acryloyloxyacrylate monomer.

[0093] Comparative Example 2

[0094] The difference between Comparative Example 2 and Example 2 is that the acryloyloxyacrylate monomer is replaced with an equal amount of methacryloyloxyacrylate monomer.

[0095] Comparative Example 3

[0096] The difference between Comparative Example 3 and Example 2 is that the branched hydroxyl polyester is replaced with an equal amount of unsaturated organosilanes.

[0097] Comparative Example 4

[0098] The difference between Comparative Example 4 and Example 2 is that the acrylate monomer B is replaced with acrylamide.

[0099] Comparative Example 5

[0100] The difference between Comparative Example 5 and Example 2 is that the unsaturated organosilane is replaced with silane coupling agent 550.

[0101] Comparative Example 6

[0102] The difference between Comparative Example 6 and Example 2 is that the amount of methacryloyloxyacrylate monomer used is swapped with the amount of acryloyloxyacrylate monomer used.

[0103] Performance testing

[0104] 1) The silicone-modified acrylic adhesives obtained in Examples 1-17 and Comparative Examples 1-6 were applied to the surface of an aluminum alloy plate, cured at 60°C for 10 min, then UV-cured for 1 min, and left for 24 h to form a coating with a thickness of 1 mm on the surface, thus obtaining the test sample.

[0105] 2) The silicone-modified acrylic adhesives obtained in Examples 1-17 and Comparative Examples 1-6 were used to bond carbon fiber sheets and aluminum alloy sheets. The adhesives were cured at 60°C for 10 min, then UV-cured for 1 min, and left for 24 h to obtain shear strength test specimens for the following test standards. The surfaces of the carbon fiber sheets and aluminum alloy sheets were flat.

[0106] Test Method / Experimental Method: Spray Test: The test sample in step 1) and the test template in step 2) were placed in the spray test device at a 45° angle. Pesticide was sprayed onto the test template and test sample through the spray device. The spray conditions of the spray test device were as follows: spray orifice diameter of 10 mm, completely covering the entire test template and test sample; pesticide flow rate of 100 L / min; spray pressure of 220 kPa; and a UV lamp (320 nm wavelength) illuminating the entire sample. The internal temperature of the UV lamp was maintained at 35°C for 7 consecutive days. After the test, the sprayed test template and test sample were removed and rinsed with clean water. The rinsing process was completely covered, with a water flow rate of 200 L / min, a spray pressure of 250 kPa, and a rinsing time of 5 min. The samples were then dried in an oven at 50°C for 2 h to obtain the sprayed test template and test sample.

[0107] The pesticide is composed of glyphosate, acetochlor, water, and nano-silica in a weight ratio of 1:1:10:0.1.

[0108] Test 1: Tensile shear strength. The test specimens before and after spraying were obtained according to the method specified in GB / T 7124-2008. The corresponding experimental data were recorded after the test. The shear strength residual was equal to the shear strength of the test specimen after spraying divided by the shear strength of the test specimen before spraying, and then multiplied by 100%.

[0109] Test 2: The contact angle was tested according to GB / T 30693-2014. The test samples were tested before and after spraying. Water droplets were dropped on the coating and the relevant experimental structure was recorded. The rate of change of the water droplet angle was equal to 1 - (the contact angle of the test sample before spraying minus the contact angle of the test sample after spraying, and then divided by the contact angle of the test sample before spraying) * 100%.

[0110] The specific experimental data are shown in Table 2.

[0111] Table 2. Experimental data of Examples 1-17 and Comparative Examples 1-6

[0112]

[0113] Combining Example 1 and Comparative Examples 1-6 with Table 2, it can be seen that the shear strength and shear strength residual of Comparative Examples 1-6 are greater than those of Example 1, indicating that the adhesive on the test sample of Example 1 has better corrosion resistance and adhesion stability. Furthermore, the water droplet angle change rate of Comparative Examples 1-6 is greater than that of Example 1, indicating that the adhesive layer on the test sample is less prone to staining or adsorption, further demonstrating that the silicone-modified acrylic adhesive of Example 1 has better easy-to-clean properties after curing. This further demonstrates that the raw material composition and dosage of this application can work synergistically to further improve the pesticide corrosion resistance and easy-to-clean properties of the cured silicone-modified acrylic adhesive, thereby improving the service life and safety of the drone.

[0114] Compared with Example 2, Examples 5, 9, 12, and 16 show that the shear strength and residual shear strength of Examples 5, 9, and 12 are greater than those of Example 2. Furthermore, the droplet angle change rate of Examples 5, 9, 12, and 16 is smaller than that of Example 2. This indicates that the present application achieves a synergistic effect by combining mono-2-(methacryloyloxy)ethyl maleate and 2-methacryloyloxyethyl phthalate; or by combining 9,9-bis[4-(2-acryloyloxyethoxy)phenyl], ethoxylated bisphenol A diacrylate, and 2-phenoxyethyl acrylate; or by combining methacrylate mono-terminated dimethyl polysiloxane and acrylate-cage-shaped polysilsesquioxane; or by combining PI powder and silicone powder, all of which further improve pesticide corrosion resistance and easy cleaning.

[0115] This is merely an explanation of the present application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A chemically resistant, easy-to-clean silicone-modified acrylic adhesive, characterized in that, It consists of the following raw materials by weight percentage: Methacryloxyacrylate monomer: 38-60% Acryloyloxyacrylate monomer: 5-20% Unsaturated organosilanes: 9-22% Branched hydroxyl polyester: 0.1-2% Nanofiller: 1-5% Initiator: 1-3% The remainder is reactive diluent; The acryloyloxyacrylate monomer is ethoxylated bisphenol A diacrylate and / or 2-phenoxyethyl acrylate; The methacryloyloxy acrylate monomer is composed of 2-methacryloyloxyethyl phthalate and mono-2-(methacryloyloxy)ethyl maleate in a weight ratio of 1:(0.5-1.5). The unsaturated organosilane is composed of methacrylate-terminated dimethyl polysiloxane and acrylate-cage-shaped polysilsesquioxane in a weight ratio of (2-3):1; The nanofiller is composed of PI powder and silicone powder in a weight ratio of (2-3):

1.

2. The chemically resistant, easy-to-clean silicone-modified acrylic adhesive according to claim 1, characterized in that: The initiator consists of a photoinitiator and a thermal initiator.

3. The chemically resistant, easy-to-clean silicone-modified acrylic adhesive according to claim 1, characterized in that: The active diluent is epoxidized soybean oil.

4. A method for preparing the chemically resistant, easy-to-clean silicone-modified acrylic adhesive according to claim 1, characterized in that, The following steps are involved: According to the weight percentage, weigh out methacryloyloxyacrylate monomer, acryloyloxyacrylate monomer, unsaturated organosilane, branched hydroxyl polyester, nanofiller, initiator and reactive diluent, mix them evenly to obtain organosilicon modified acrylic adhesive.

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