Coating composition and use thereof

Abstract

The invention provides a coating composition which comprises the following components in parts by mass: 50-70 parts of liquid isoparaffin, 5-25 parts of MQ silicon resin, 5-20 parts of dimethyl silicone oil and 1-10 parts of fumed silica, the viscosity of the dimethyl silicone oil at 25 DEG C is 3000-100000 cst, and the mass ratio of the dimethyl silicone oil to the MQ silicon resin is 1: 3-3: 1. The number average molecular weight of the MQ silicon resin is 2800 to 6000. The invention also provides application of the coating composition. The coating composition provided by the invention has better hydrophobicity, corrosion resistance and insulativity after being cured to form a coating, and is beneficial to improving the water resistance and the insulating property, so that the foaming time under preset voltage can be prolonged or the foaming voltage can be improved within preset time.

Description

Technical Field

[0001] This invention relates to the technical field of coating materials, and more specifically to a coating composition and its application. Background Technology

[0002] Electronic devices consist of conductive and insulating components and are susceptible to adverse effects from various contaminants, requiring protective coatings. Common methods for protecting insulating components include conformal coatings and vacuum coatings. However, the water resistance and insulation properties of current protective coatings for electronic devices need improvement. One issue is that coatings are prone to blistering and failure when energized underwater, making them unsuitable for protecting conductive components. Furthermore, current protective coatings only achieve hydrophobic effects, providing protection in low-humidity environments. In high-humidity environments, such as when high air humidity causes condensation on the surface of electronic devices, or when the device needs to be operated underwater or accidentally dropped into water, current hydrophobic coatings may fail when energized. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the present invention aims to provide a coating composition that, after curing, forms a coating with good hydrophobicity, corrosion resistance and insulation, and is beneficial to improving water resistance and insulation performance.

[0004] To solve the above problems, the technical solution adopted by the present invention is as follows: A coating composition, by weight parts, comprises 50-70 parts of liquid isoparaffin, 5-25 parts of MQ silicone resin, 5-20 parts of dimethyl silicone oil, and 1-10 parts of fumed silica, wherein the dimethyl silicone oil has a viscosity of 3000-100000 cst at 25°C, the mass ratio of the dimethyl silicone oil to the MQ silicone resin is 1:3-3:1, and the number average molecular weight of the MQ silicone resin is 2800-6000.

[0005] In some possible implementations, the M / Q ratio of the MQ silicone resin is 0.6-0.9, and the viscosity of the dimethyl silicone oil at 25°C is 3000-10000 cst.

[0006] In some possible implementations, the mass ratio of the dimethyl silicone oil to the MQ silicone resin is 1:1 to 3:1, and the number average molecular weight of the MQ silicone resin is 2800-3200.

[0007] In some possible implementations, the mass ratio of the dimethyl silicone oil to the MQ silicone resin is 1:1, and the number-average molecular weight of the MQ silicone resin is 3000.

[0008] In some possible implementations, the M / Q ratio of the MQ silicone resin is 0.8, and the mass ratio of the dimethyl silicone oil to the MQ silicone resin is 2:1.

[0009] In some possible implementations, the mass ratio of the dimethyl silicone oil to the MQ silicone resin is 1:2, the number average molecular weight of the MQ silicone resin is 4000-6000, and the M / Q ratio of the MQ silicone resin is 0.6-0.7.

[0010] In some possible implementations, the total number of carbon atoms in the liquid isoalkane is 6-8.

[0011] In some possible embodiments, the coating composition further includes 0.05-0.5 parts of phosphor by weight.

[0012] In some possible implementations, the MQ silicone resin is selected from methyl MQ silicone resin.

[0013] The coating composition is applied to the surface of a workpiece, whereby the liquid isoalkane evaporates and forms a coating on the workpiece surface, the coating covering at least the conductive parts of the workpiece.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: In this application, the synergistic effect is achieved by combining MQ silicone resin, dimethyl silicone oil and fumed silica in a specific ratio, so that the coating formed by curing the composition has good hydrophobicity, corrosion resistance and insulation, and is conducive to improving water resistance and insulation performance, which is manifested in extending the foaming time in water at a predetermined voltage or being able to increase the voltage when foaming in water within a predetermined time.

[0015] The present invention will be further described in detail below with reference to specific embodiments. Detailed Implementation

[0016] The technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0018] The following describes some embodiments of the present invention in detail. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0019] One embodiment of this application provides a coating composition comprising, by weight parts, 50-70 parts of liquid isoparaffin, 5-25 parts of MQ silicone resin, 5-20 parts of dimethyl silicone oil, and 1-10 parts of fumed silica. The dimethyl silicone oil has a viscosity of 3000-10000 cst at 25°C. The mass ratio of dimethyl silicone oil to MQ silicone resin is 1:3-3:1, i.e., the mass ratio of dimethyl silicone oil to MQ silicone resin is one-third to three. The number average molecular weight of the MQ silicone resin is 2800-6000. The liquid isoparaffin is used as a solvent. Exemplarily, the MQ silicone resin is preferably methylMQ silicone resin.

[0020] In this application, the synergistic effect is achieved by combining MQ silicone resin, dimethyl silicone oil and fumed silica in a specific ratio, so that the coating formed by curing the composition has good hydrophobicity, corrosion resistance and insulation, and is conducive to improving water resistance and insulation performance, which is manifested in extending the foaming time in water at a predetermined voltage or being able to increase the voltage when foaming in water within a predetermined time.

[0021] Another embodiment of this application also provides the use of a coating composition. The coating composition is applied to the surface of a workpiece, and after the liquid isoalkane evaporates, a coating is formed on the workpiece surface. The coating at least covers the conductive components of the workpiece. For example, the workpiece may include an electronic device component, and for example, the electronic device component may include a circuit board. The coating composition provided in this application can be used to protect the insulating and conductive components of electronic devices, or it can be used only to protect the conductive components of electronic devices. Specifically, the components of the coating composition are mixed uniformly by physical mixing, and then the coating composition is applied to the surface of the workpiece and cured to form a coating. For example, physical mixing can be achieved by stirring. Specifically, dimethyl silicone oil, fumed silica, and MQ resin are added to a container and dispersed using a homogenizer at 3000 rpm for 15 minutes to obtain component A. A fluorescent agent is pre-dissolved in the liquid isoalkane to obtain component B. Finally, component B is added to component A (if there is no fluorescent agent, the liquid isoalkane can be directly added to component A), and dispersed using a homogenizer at 3000 rpm for 10 minutes to obtain the coating composition. The coating composition can be applied to IPC standard boards (circuit boards) via spraying or blade coating. Spraying parameters: atomization pressure 0.02~0.2MPa, spraying speed 150~300mm / s, spraying spacing 10mm, spraying height 6~10cm. Blasting is performed using a blade coating instrument with a thickness of 125µm. The wet film thickness is controlled at 120~130µm. After application, the composition is cured by natural solvent evaporation.

[0022] Preferably, the coating composition containing MQ silicone resin with a number average molecular weight of 3500 or higher can be applied to the workpiece surface by spraying. Preferably, the coating composition containing MQ silicone resin with a number average molecular weight of 3500 or lower can be applied to the workpiece surface by blade coating.

[0023] In some embodiments, the M / Q ratio of the MQ silicone resin is 0.6-0.9, and the viscosity of the dimethyl silicone oil at 25°C is 3000-10000 cst.

[0024] In some embodiments, the mass ratio of the dimethyl silicone oil to the MQ silicone resin is 1:1 to 3:1, and the number-average molecular weight of the MQ silicone resin is 2800-3200. Limiting the molecular weight and mass ratio helps to further improve the water-resistant insulation properties.

[0025] In some embodiments, the mass ratio of the dimethyl silicone oil to the MQ silicone resin is 1:1, and the number average molecular weight of the MQ silicone resin is 3000. Further optimization of the mass ratio and molecular weight selection helps to increase the energizing voltage when the coating foams underwater at a predetermined time, so that the coating does not foam after being energized at 130V for 5 minutes.

[0026] In some embodiments, the mass ratio of the dimethyl silicone oil to the MQ silicone resin is 1:2, the number average molecular weight of the MQ silicone resin is 4000-6000, and the M / Q ratio of the MQ silicone resin is 0.6-0.7. Similarly, further optimization of the selection of the mass ratio, molecular weight, and M / Q ratio is beneficial to increasing the energizing voltage when bubbling occurs underwater at a predetermined time, so that the coating does not bubble after being energized at 130V for 5 minutes.

[0027] In some embodiments, the liquid isoalkane has a total carbon number of 6-8, that is, the liquid isoalkane can be selected from isohexane, isoheptane, and isooctane. For example, isohexane can be selected from at least one of 2-methylpentane and 3-methylpentane. For example, isoheptane can be selected from at least one of 2-methylhexane and 3-methylhexane, and for example, isooctane can be selected from 2,2,4-trimethylpentane. Selecting liquid isoalkane with a total carbon number of 6-8 is to improve ease of application.

[0028] In some embodiments, the MQ silicone resin is selected from methyl MQ silicone resin.

[0029] In some embodiments, the coating composition further includes 0.05-0.5 parts by weight of phosphor, which is used for fluorescence and has little effect on the mechanical properties, protective properties, and water resistance and insulation properties of the coating. Therefore, the phosphor component can be added as needed according to the luminescence requirements.

[0030] Example 1 A coating composition, by weight, comprises 70 parts of liquid isoparaffin (2-methylpentane, CAS No. 107-83-5, Aladdin), 18 parts of MQ silicone resin (methylMQ silicone resin, model 5204P, Hubei Longsheng Sihai New Materials Co., Ltd.), 6 parts of dimethyl silicone oil, 5.5 parts of fumed silica (model R812s, purchased by Evonik Degussa), and 0.5 parts of phosphor (2,5-bis(5-tert-butyl-2-benzoxazolyl)thiophene, model OBCO, manufactured by BASF), the dimethyl silicone oil (CAS No. 9006-65-9, model SH-201-5000, manufactured or purchased by Hubei Longsheng Sihai New Materials Co., Ltd.) having a viscosity of 5000 cst at 25°C, the mass ratio of dimethyl silicone oil to MQ silicone resin being 1:3, and the number average molecular weight of MQ silicone resin being 2800-3200. The M / Q ratio of MQ silicone resin is 0.8.

[0031] The mixing of the composition includes: adding dimethyl silicone oil, fumed silica, and MQ resin into a container and dispersing them using a homogenizer at 3000 rpm for 15 min to obtain component A. Separately, pre-dissolving the fluorescent agent in liquid isoalkane to obtain component B. Finally, adding component B to component A and dispersing it using a homogenizer at 3000 rpm for 10 min yields the final product.

[0032] The coating composition was applied to the workpiece using a blade coating instrument with a thickness of 125 μm. The wet film thickness was controlled between 120 and 130 μm. The coating was cured by natural solvent evaporation.

[0033] Examples 2-5 The difference from Example 1 is that the mass ratio of dimethyl silicone oil to MQ silicone resin is different, as shown in Table 1. The underwater bubbling of the coatings in Examples 1 to 5 is also summarized in Table 1.

[0034] Table 1 is a statistical table of underwater bubbling of the coatings in Examples 1 to 5.

[0035] Example 6 The difference from Example 1 lies in the use of a different MQ silicone resin. In this example, the MQ silicone resin is model 5031P (methyl MQ silicone resin, manufactured or purchased from Hubei Longsheng Sihai New Materials Co., Ltd.). The number average molecular weight of the MQ silicone resin is 3000. The M / Q ratio of the MQ silicone resin is 0.6-0.9.

[0036] Examples 7-10 The difference from Example 6 is that the mass ratio of dimethyl silicone oil to MQ silicone resin is different, as shown in Table 2. The underwater bubbling of the coatings in Examples 6 to 10 is also summarized in Table 2.

[0037] Table 2 is a statistical table of underwater bubbling of the coatings in Examples 7 to 10.

[0038] Analysis of the data in Tables 1 and 2 reveals that when using low molecular weight (2800-3200) MQ silicone resin, setting the mass ratio of dimethyl silicone oil to MQ silicone resin to 1:1-3:1 results in better water resistance and insulation performance. Further optimization of the mass ratio of dimethyl silicone oil to MQ silicone resin (1:1 or 2:1), the molecular weight of MQ silicone resin, and the M / Q ratio of MQ silicone resin (0.8) are beneficial for maximizing the water resistance and insulation performance of the coating.

[0039] Example 11 The difference from Example 1 lies in the use of a different MQ silicone resin. In this example, the MQ silicone resin is model XJY-8205-03 (methyl MQ silicone resin, manufactured by Jiangxi Xinjiayi New Material Co., Ltd.). The number average molecular weight of the MQ silicone resin is 4000-6000. The M / Q ratio of the MQ silicone resin is 0.6-0.7. The mass fraction of the MQ silicone resin is 12 parts, and the mass ratio of dimethyl silicone oil to MQ silicone resin is 1:2. The coating composition is applied to the surface of the workpiece by spraying. The spraying parameters are: atomization pressure 0.02~0.2MPa, spraying speed 150~300mm / s, spraying spacing 10mm, and spraying height 6~10cm.

[0040] Example 12 The difference from Example 11 is that the mass fraction of MQ silicone resin is 6 parts, and the mass ratio of dimethyl silicone oil to MQ silicone resin is 1:1.

[0041] Example 13 The difference from Example 11 is that the mass fraction of MQ silicone resin is 25 parts, and the mass fraction of dimethyl silicone oil is 9 parts. The mass ratio of dimethyl silicone oil to MQ silicone resin is 9:25.

[0042] The underwater bubbling of the coatings in Examples 11 to 13 is summarized in Table 3.

[0043] Table 3 is a statistical table of underwater bubbling of the coatings in Examples 11 to 13.

[0044] Example 14 The difference from Example 11 is that the viscosity of the dimethyl silicone oil at 25°C is 10000 cst (SH-201-10000, Hubei Longsheng Sihai New Material Co., Ltd.).

[0045] Example 15 The difference from Example 11 is that the dimethyl silicone oil has a viscosity of 20,000 cst at 25°C (brand name SH-201-20000, Hubei Longsheng Sihai New Material Co., Ltd.). Example 16 The difference from Example 11 is that the dimethyl silicone oil has a viscosity of 100,000 cst at 25°C (brand name SH-201-100000, Hubei Longsheng Sihai New Material Co., Ltd.). Example 17 The difference from Example 11 is that the dimethyl silicone oil has a viscosity of 3000 cst at 25°C (brand name QL-200DM3000, Huangshan Qiangli Chemical Co., Ltd.).

[0046] Comparative Example 1 The difference from Example 11 is that the viscosity of the dimethyl silicone oil at 25°C is 1000 cst (brand name QL-200DM1000, Huangshan Qiangli Chemical Co., Ltd.).

[0047] The underwater bubbling of the coatings in Examples 11, 14 to 17, and Comparative Example 1 is summarized in Table 4.

[0048] Table 4 is a statistical table of underwater bubbling of the coatings in Examples 11, 14 to 17, and Comparative Example 1.

[0049] Based on Table 4 and the composition information of Examples 11, 14 to 17, and Comparative Example 1, it can be seen that when the viscosity of dimethyl silicone oil is 3000-100000 cst, the coating composition can form a coating that will not bubble for at least 2 minutes under a 20V voltage. When the viscosity of dimethyl silicone oil is 3000-10000 cst, the water resistance and insulation performance are better. When the viscosity of dimethyl silicone oil is below 3000 cst, the coating will bubble within 20 seconds under a 20V voltage. Furthermore, when the viscosity of dimethyl silicone oil continues to increase above 10000 cst, the water resistance and insulation performance remain stable, and it is not conducive to further increasing the voltage at which bubbling occurs. Therefore, the preferred viscosity of dimethyl silicone oil is 3000-10000 cst.

[0050] Example 18 The difference from Example 11 is that the liquid isoalkane used is 3-methylhexane (CAS No. 589-34-4, brand name: Anaiji).

[0051] Example 19 The difference from Example 11 is that the liquid isoalkane used is 2,2,4-trimethylpentane (CAS No. 540-84-1, Aladdin). The underwater bubbling of the coatings in Examples 11, 18 and 19 is summarized in Table 5.

[0052] Table 5 is a statistical table of underwater bubbling of the coatings in Examples 11, 18, and 19 under electrical conduction.

[0053] Example 20 The difference from Example 11 is that the mass fraction of fumed silica is 10 parts and the mass fraction of liquid isoalkanes is 50 parts.

[0054] Example 21 The difference from Example 11 is that the mass fraction of fumed silica is 1 part and the mass fraction of liquid isoalkanes is 50 parts.

[0055] Example 22 The difference from Example 4 is that the mass fraction of fumed silica is 1 part and the mass fraction of liquid isoparaffin is 50 parts.

[0056] Example 23 The difference from Example 4 is that the mass fraction of fumed silica is 10 parts and the mass fraction of liquid isoparaffin is 50 parts.

[0057] The underwater bubbling of the coatings in Examples 4, 11, and 20-23 is summarized in Table 6.

[0058] Table 6 is a statistical table of underwater bubbling of the coatings in Examples 4, 11, and 20-23 under electrical conduction.

[0059] Example 24 The difference from Example 1 is that the mass fraction of the phosphor is 0.05 parts.

[0060] Example 25 The difference from Example 1 is that the mass fraction of the phosphor is 0 parts, and when the composition is mixed, the liquid isoparaffin is directly added to component A.

[0061] The underwater bubbling of the coatings in Examples 1, 25, and 26 is summarized in Table 7.

[0062] Table 7 is a statistical table of underwater bubbling of the coatings in Examples 1, 25, and 26 under electrical conduction.

[0063] Comparative Example 2 The difference from Example 13 is that the mass fraction of MQ silicone resin is 27 parts, the mass fraction of dimethyl silicone oil is 5 parts, and the mass ratio of dimethyl silicone oil to MQ silicone resin is 5:27.

[0064] Comparative Example 3 The difference from Example 13 is that the mass fraction of MQ silicone resin is 5 parts, the mass fraction of dimethyl silicone oil is 21 parts, and the mass ratio of dimethyl silicone oil to MQ silicone resin is 21:5.

[0065] The underwater bubbling conditions of the coatings in Examples 13 and Comparative Examples 2-3 are summarized in Table 8. Table 8 is a statistical table of underwater bubbling of the coatings in Examples 13 and Comparative Examples 2-3.

[0066] The coatings formed after curing in the above embodiments and comparative examples were also subjected to water droplet angle tests, neutral salt spray resistance tests, 50wt% ethylene glycol solution resistance tests, and electrical performance tests. The test data for these embodiments and comparative examples are not significantly different, and therefore will not be repeated. ° -109 ° Therefore, the coatings exhibit good hydrophobicity. No abnormalities were observed in neutral salt spray tests and tests against 50wt% ethylene glycol solution, and the dielectric strength of the coatings is >40kV / mm. All of the above coatings possess good hydrophobicity, corrosion resistance, and insulation properties.

[0067] The specific procedures or national standards followed for each test item are shown in the table below.

[0068]

[0069] In the above tests, except for the ethylene glycol solution resistance test which is conducted by forming the coating on the surface of the aluminum plate, all the other tests are conducted by covering the surface of the circuit board with the coating.

[0070] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A coating composition characterized in that, The coating composition comprises 50-70 parts by mass of liquid isoparaffin, 5-25 parts by mass of MQ silicone resin, 5-20 parts by mass of dimethyl silicone oil with 25 DEG C viscosity of 3000-100000 cst, and 1-10 parts by mass of fumed silica, the mass ratio of the dimethyl silicone oil to the MQ silicone resin is 1:3-3:1, and the number average molecular weight of the MQ silicone resin is 2800-6000.

2. The coating composition of claim 1, wherein, The M / Q ratio of the MQ silicone resin is 0.6-0.9, and the 25 DEG C viscosity of the dimethyl silicone oil is 3000-10000 cst.

3. The coating composition of claim 2, wherein, The mass ratio of the dimethyl silicone oil to the MQ silicone resin is 1:1-3:1, and the number average molecular weight of the MQ silicone resin is 2800-3200.

4. The coating composition of claim 3, wherein, The mass ratio of the dimethyl silicone oil to the MQ silicone resin is 1:1, and the number average molecular weight of the MQ silicone resin is 3000.

5. The coating composition of claim 3, wherein The M / Q ratio of the MQ silicone resin is 0.8, and the mass ratio of the dimethyl silicone oil to the MQ silicone resin is 2:

1.

6. The coating composition of claim 2, wherein The mass ratio of the dimethyl silicone oil to the MQ silicone resin is 1:2, the number average molecular weight of the MQ silicone resin is 4000-6000, and the M / Q ratio of the MQ silicone resin is 0.6-0.

7.

7. The coating composition according to claim 1, wherein The total carbon number of the liquid isoparaffin is 6-8.

8. The coating composition according to claim 1, wherein The coating composition further comprises 0.05-0.5 parts by mass of fluorescent powder.

9. The coating composition according to any one of claims 1 to 8, wherein The MQ silicone resin is selected from methyl MQ silicone resin.

10. Use of a coating composition according to any one of claims 1 to 9, characterized in that The liquid isoparaffin is applied to the surface of the workpiece, and a coating is formed on the surface of the workpiece after the liquid isoparaffin is volatilized, the coating covering at least the conductive part of the workpiece.

Images