Solvent-free superfine high-thermal-conductivity insulating paint as well as preparation method and application thereof

Abstract

The invention discloses a solvent-free superfine high-thermal-conductivity insulating coating and a preparation method and application thereof, and the coating comprises 30-50% wt of a resin film-forming composition, 10-20% wt of an epoxy reactive diluent, 0.3-1.3% wt of a wetting leveling agent, 2-5% wt of a dispersant, 0.5-1% wt of an antifoaming agent, 16-20% wt of a curing agent, and 40-70% wt of an inorganic filler. Wherein the inorganic filler is prepared from 3 to 10 weight percent of diamond powder, 10 to 30 weight percent of spherical aluminum oxide powder, 15 to 25 weight percent of aluminum hydroxide powder and 5 to 15 weight percent of titanium dioxide. The coating obtained by adopting the formula disclosed by the invention is fine and smooth, has the characteristics of high heat conductivity and high insulation, reduces heat radiation, and also increases the heat conduction function of the coating, so that the requirements of the vehicle-mounted power battery are well met, and a solid foundation is laid for improving the safety of the vehicle-mounted power battery.

Description

Technical Field

[0001] This invention belongs to the field of insulating coating technology, specifically relating to a solvent-free ultrafine high thermal conductivity insulating coating, its preparation method, and its application. Background Technology

[0002] In recent decades, the environmental problems caused by the greenhouse effect have attracted great attention from the world. In order to reduce carbon emissions, new energy vehicles, based on their zero-emission and green environmental protection characteristics, have gradually replaced gasoline vehicles.

[0003] For new energy vehicles, in order to meet the requirement of longer driving range, the power batteries used in new energy electric vehicles often adopt a metal casing design. However, the inner and outer surfaces of the casing of lithium-ion batteries can easily come into contact with the cell or conductive materials of the external environment, causing leakage or short circuit. At the same time, the power battery has a high power when in use, and if used for a long time, it will cause a lot of heat to accumulate around it. Therefore, insulation and heat conduction treatment are necessary.

[0004] To achieve the above objectives, coating with insulating films and spraying with insulating powder coatings are currently the most common treatment methods. However, insulating films are bonded to the metal surface with adhesives, and over time, the adhesives lose their stickiness, causing the film to detach. Furthermore, the film is soft and offers no impact resistance. Powder coatings offer good insulation, but their curing temperature is too high, requiring 160-180℃, resulting in significant energy consumption.

[0005] Therefore, developing a new type of insulating powder coating remains one of the main topics that researchers are currently working on. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a solvent-free ultrafine high thermal conductivity insulating coating, which solves the problem that the performance and effect of existing insulating coatings of this kind are not good when used in lithium batteries of new energy vehicles.

[0007] The present invention also aims to provide a method for preparing a solvent-free, ultrafine, high thermal conductivity insulating coating.

[0008] To solve the above problems, the technical solution adopted by the present invention is: a solvent-free ultrafine high thermal conductivity insulating coating, characterized in that the coating comprises 30-50% wt resin film-forming composition, 10-20% epoxy reactive diluent, 0.3-1.3% wt wetting and leveling agent, 2-5% wt dispersant, 0.5-1% wt defoamer, 16-20% wt curing agent, and 40-70% wt inorganic filler; wherein the inorganic filler comprises 3-10% wt diamond powder, 10-30% wt spherical alumina powder, 15-25% wt aluminum hydroxide powder, and 5-15% wt titanium dioxide.

[0009] Preferably, the resin film-forming composition is selected from at least one of polyurethane resin, acrylic resin, and epoxy resin.

[0010] Preferably, the wetting and leveling agent is selected from one or more of BYK302, BYK378, BYK325, BYK331, UNIQFLOW375S, and Efka SL3239 and used in combination; the dispersant is selected from one or more of BYK110, BYK163, BYK168, EfkaFA4611, BYK9076, and BYK2009 and used in combination; and the defoamer is selected from one or more of Xinyue KSZ-108, Dow Corning ACP-1400, BYK-066N, and BYK-530A and used in combination.

[0011] Preferably, the curing agent is at least one of reactive polyamide resin curing agents, aliphatic amine curing agents, and cycloaliphatic amine curing agents.

[0012] Preferably, the diamond powder has a particle size of 300–500 nm; the spherical alumina powder has a particle size of 300–700 nm; the aluminum hydroxide powder has a particle size of 700–3000 nm; and the titanium dioxide has a particle size of 300–500 nm.

[0013] Preferably, the diamond powder, spherical alumina powder, aluminum hydroxide powder, and titanium dioxide in the inorganic filler all need to undergo surface treatment, specifically any one of dry modification, wet modification, or gas-phase modification.

[0014] Preferably, the wet modification method specifically involves: taking an aqueous solution of KH570 containing 2-8% by mass of silane coupling agent, adjusting the pH value to 3-5 with oxalic acid, and maintaining it at room temperature for 30-60 minutes to allow the silane coupling agent to be fully hydrolyzed; heating each powder component in the inorganic filler to 30-70°C, and spraying it with the above-mentioned coupling agent aqueous solution, maintaining it for 2-6 hours after complete wetting, vacuum drying at 50-70°C for 20-30 hours, sieving and classifying, and waiting for use.

[0015] Preferably, the volume resistivity of the solvent-free ultrafine high thermal conductivity insulating coating is DC1000V, ≥1000MΩ; the leakage current is DC6500V, lasting 60S, and the leakage current is <1mA.

[0016] The second technical solution of the present invention is achieved as follows: a method for preparing a solvent-free ultrafine high thermal conductivity insulating coating, characterized in that the method specifically includes the following steps:

[0017] S1. Weigh out the following components according to the specified quantities: 30-50% wt epoxy film-forming composition, 10-20% epoxy reactive diluent, 0.3-1.3% wt wetting and leveling agent, 2-5% wt dispersant, 0.5-1% wt defoamer, and 40-70% wt inorganic filler; wherein the inorganic filler includes 3-10% wt diamond powder, 10-30% wt spherical alumina powder, 15-25% wt aluminum hydroxide powder, and 5-15% wt titanium dioxide.

[0018] S2. The weighed epoxy reactive diluent, wetting and leveling agent and dispersant are added to the epoxy film-forming composition in sequence while stirring to carry out slow dispersion treatment, so as to obtain an intermediate mixture after slow dispersion.

[0019] S3. Add the defoamer and inorganic filler to the dispersed intermediate mixture while stirring, and then perform medium-speed dispersion treatment to obtain the medium-speed dispersed intermediate mixture.

[0020] S4. Transfer the intermediate mixture after medium-speed dispersion to a sand mill, select zirconium beads of 0.3-0.4 mm, and grind until the fineness is less than 5 μm to obtain the coating precursor;

[0021] S5. Add the curing agent to the coating precursor while stirring, and stir to obtain a solvent-free ultrafine high thermal conductivity insulating coating.

[0022] Preferably, the stirring rate during the slow dispersion process in S2 is 400-500 rpm, and the stirring time is 2-5 min.

[0023] Preferably, the stirring rate during the medium-speed dispersion process in S3 is 800-1500 rpm, and the stirring time is 5-30 min.

[0024] Preferably, in step S5, the stirring rate is 500-600 rpm and the stirring time is 8-15 min.

[0025] The third technical solution of the present invention is achieved as follows: the application of the above-mentioned solvent-free ultrafine high thermal conductivity insulating coating on the battery compartment of lithium batteries for new energy vehicles.

[0026] Compared with existing technologies, the coating obtained by the formulation of this invention is fine and not only has high thermal conductivity and high insulation properties, but also reduces heat radiation and increases the thermal conductivity of the coating, thus well meeting the needs of vehicle power batteries and laying a solid foundation for improving the safety of vehicle power batteries. In addition, the preparation method of this invention is simple and the raw materials are simple and readily available, making it very suitable for mass production and promoting its widespread use. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0028] This invention provides a solvent-free, ultrafine, high thermal conductivity insulating coating, comprising 30-50% wt resin film-forming composition, 10-20% epoxy reactive diluent, 0.3-1.3% wt wetting and leveling agent, 2-5% wt dispersant, 0.5-1% wt defoamer, 16-20% wt curing agent, and 40-70% wt inorganic filler; wherein the inorganic filler comprises 3-10% wt diamond powder, 10-30% wt spherical alumina powder, 15-25% wt aluminum hydroxide powder, and 5-15% wt titanium dioxide.

[0029] Furthermore, the resin film-forming composition is selected from at least one of polyurethane resin, acrylic resin, and epoxy resin, but solvent-free epoxy resin is preferred considering properties such as metal adhesion and corrosion resistance.

[0030] Furthermore, the wetting and leveling agent is selected from one or more of BYK302, BYK378, BYK325, BYK331, UNIQFLOW375S, and Efka SL3239, used in combination; the dispersant is selected from one or more of BYK110, BYK163, BYK168, EfkaFA4611, BYK9076, and BYK2009, used in combination; the defoamer is selected from one or more of Shin-Etsu KSZ-108, Dow Corning ACP-1400, BYK-066N, and BYK-530A, used in combination. It should be noted that there are no special requirements for the wetting and leveling agent and the dispersant; they are suitable for solvent-free coatings and only need to meet the requirements of the coating.

[0031] Furthermore, considering environmental protection and energy conservation factors, the curing agent is preferably a reactive polyamide resin curing agent.

[0032] Further, the diamond powder has a particle size of 300–500 nm; the spherical alumina powder has a particle size of 300–700 nm; the aluminum hydroxide powder has a particle size of 700–3000 nm; and the titanium dioxide has a particle size of 300–500 nm. The diamond powder, spherical alumina powder, aluminum hydroxide powder, and titanium dioxide in the inorganic filler all require surface treatment. The specific treatment method is any one of dry modification, wet modification, or gas-phase modification. The wet modification method specifically involves: taking a KH570 aqueous solution containing 2–8% (by mass) of silane coupling agent, adjusting the pH to 3–5 with oxalic acid, and maintaining the solution at room temperature for 30–60 minutes to allow the silane coupling agent to fully hydrolyze; heating each powder component in the inorganic filler to 30–70°C, and spraying it with the above-mentioned coupling agent aqueous solution; maintaining the solution for 2–6 hours after complete wetting; vacuum drying at 50–70°C for 20–30 hours; sieving and grading; and then waiting for use.

[0033] Furthermore, the volume resistivity of this solvent-free ultrafine high thermal conductivity insulating coating is ≥1000MΩ at DC1000V; the leakage current is <1mA at DC6500V for 60S.

[0034] This invention also provides a method for preparing the above-mentioned solvent-free ultrafine high thermal conductivity insulating coating, which specifically includes the following steps:

[0035] S1. Weigh out the following components according to the specified quantities: 30-50% wt epoxy film-forming composition, 10-20% epoxy reactive diluent, 0.3-1.3% wt wetting and leveling agent, 2-5% wt dispersant, 0.5-1% wt defoamer, and 40-70% wt inorganic filler; wherein the inorganic filler includes 3-10% wt diamond powder, 10-30% wt spherical alumina powder, 15-25% wt aluminum hydroxide powder, and 5-15% wt titanium dioxide.

[0036] S2. The weighed epoxy reactive diluent, wetting and leveling agent and dispersant are added to the epoxy film-forming composition in sequence while stirring to carry out slow dispersion treatment, so as to obtain an intermediate mixture after slow dispersion.

[0037] S3. Add the defoamer and inorganic filler to the dispersed intermediate mixture while stirring, and then perform medium-speed dispersion treatment to obtain the medium-speed dispersed intermediate mixture.

[0038] S4. Transfer the intermediate mixture after medium-speed dispersion to a sand mill, select zirconium beads of 0.3-0.4 mm, and grind until the fineness is less than 5 μm to obtain the coating precursor;

[0039] S5. Add the curing agent to the coating precursor while stirring, and stir to obtain a solvent-free ultrafine high thermal conductivity insulating coating.

[0040] Furthermore, in S2, the stirring rate during slow dispersion is 400-500 rpm and the stirring time is 2-5 min; in S3, the stirring rate during medium-speed dispersion is 800-1500 rpm and the stirring time is 5-30 min; in S5, the stirring rate is 500-600 rpm and the stirring time is 8-15 min.

[0041] This invention also provides the application of the above-mentioned solvent-free ultrafine high thermal conductivity insulating coating in new energy vehicle lithium batteries.

[0042] The following are specific embodiments.

[0043] It should be noted that the following is a list of raw materials used in the following embodiments:

[0044] The epoxy resin used is Hansen 862 (epoxy equivalent 165-173 g / equivalent), the epoxy reactive diluent used is Shanghe Technology's S-7400, the reactive polyamide resin used is Shanghe Technology's TSG-7095AN, the wetting and leveling agent used is BYK325, the dispersant used is BYK168, the defoamer used is BYK-066N, the diamond used is 300nm-500nm grade diamond powder from Henan Yuxing Micro-Drilling, the spherical alumina used is Ya'an Baitu's NSM-1S, the aluminum hydroxide used is Zhonglv's H-WF-01-SP 8000 mesh aluminum hydroxide, and the titanium dioxide used is Nanjing Tianxing's R30.

[0045] Example 1

[0046] The solvent-free ultrafine high thermal conductivity insulating coating provided in Example 1 of this invention comprises the following components in parts by weight:

[0047] 33 parts of solvent-free epoxy resin (epoxy equivalent 165-173 g / eq), 5 parts of epoxy reactive diluent, 0.5 parts of wetting and leveling agent, 3.5 parts of dispersant, 0.5 parts of defoamer, 5 parts of diamond, 10 parts of spherical alumina, 18 parts of aluminum hydroxide, 6 parts of titanium dioxide, and 18.5 parts of reactive polyamide resin (amine equivalent 95).

[0048] The surface of the inorganic filler powders (diamond with a particle size of 400 nm, spherical alumina with a particle size of 500 nm, aluminum hydroxide with a particle size of 1800 nm, and titanium dioxide with a particle size of 400 nm) was treated by the following method:

[0049] Take a 5% aqueous solution of silane coupling agent KH570, adjust the pH value to 3-5 with oxalic acid, and keep it at room temperature for 30-60 minutes to allow the silane coupling agent to be fully hydrolyzed, thus obtaining an aqueous solution of coupling agent;

[0050] The powder (diamond, spherical alumina, aluminum hydroxide, titanium dioxide) is heated to 50°C. The above coupling agent aqueous solution is sprayed onto the heated powder. After the heated powder is completely wetted, it is kept for 4 hours, and then dried under vacuum at 60°C for 24 hours. It is then sieved and classified, ready for use.

[0051] The solvent-free ultrafine high thermal conductivity insulating coating provided in Example 1 of this invention is obtained by the following method:

[0052] 1) Weigh 33 parts of solvent-free epoxy resin (epoxy equivalent 165-173 g / eq) and stir at a speed of 400-500 rpm.

[0053] 2) Weigh 5 parts of epoxy diluent and add it to the above solvent-free epoxy resin while stirring to obtain the first intermediate mixture; and the stirring speed is 400-500 rpm and the stirring time is 5 min;

[0054] 3) Weigh 0.5 parts of wetting and leveling agent and add it to the first intermediate mixture obtained above while stirring to obtain the second intermediate mixture; the stirring speed is 400-500 rpm and the stirring time is 2 min;

[0055] 4) Weigh 3.5 parts of dispersant and add it to the second intermediate mixture above while stirring to obtain the third intermediate mixture. The stirring speed is 400-500 rpm and the stirring time is 2 min.

[0056] 5) Weigh 0.5 parts of defoamer and add it to the third intermediate mixture above while stirring to obtain the fourth intermediate mixture. The stirring speed is 800-1000 rpm and the stirring time is 5 min.

[0057] 6) Weigh 5 parts of diamond and add them to the fourth intermediate mixture above while stirring to obtain the fifth intermediate mixture. The stirring speed is 800-1000 rpm and the stirring time is 5 min.

[0058] 7) Weigh 10 parts of spherical alumina and add them to the fifth intermediate mixture above while stirring to obtain the sixth intermediate mixture. The stirring speed is 800-1000 rpm and the stirring time is 5 min.

[0059] 8) Weigh 6 parts of spherical titanium dioxide and add it to the sixth intermediate mixture above while stirring to obtain the seventh intermediate mixture. The stirring speed is 300-1500 rpm and the stirring time is 30 min.

[0060] 9) Transfer the above seventh intermediate mixture to a sand mill, select 0.3-0.4 mm abrasive beads, grind until the fineness is less than 5 μm, and obtain the ground mixture for later use;

[0061] 10) Add reactive polyamide resin curing agent to the above-ground mixture while stirring to carry out the curing reaction, and obtain solvent-free ultrafine high thermal conductivity insulating coating. The stirring speed is 500-600 rpm and the stirring time is 10 min.

[0062] Example 2:

[0063] The solvent-free ultrafine high thermal conductivity insulating coating provided in Example 2 of this invention comprises the following components in parts by weight:

[0064] 33 parts solvent-free epoxy resin (epoxy equivalent 165-173 g / eq), 5 parts epoxy reactive diluent, 0.5 parts wetting and leveling agent, 3.5 parts dispersant, 0.5 parts defoamer, 8 parts diamond, 20 parts spherical alumina, 20 parts aluminum hydroxide, 6 parts titanium dioxide, and 18.5 parts reactive polyamide resin (amine equivalent 95).

[0065] In this Example 2, the surface treatment method for the inorganic filler powder (diamond with a particle size of 400 nm, spherical alumina with a particle size of 500 nm, aluminum hydroxide with a particle size of 1800 nm, and titanium dioxide with a particle size of 400 nm) is the same as that in Example 1. The difference is that the weight proportions of diamond, spherical alumina, aluminum hydroxide, and titanium dioxide in the inorganic filler powder are different from those in Example 1.

[0066] Furthermore, the preparation method of the coating in this Example 2 is the same as that in Example 1.

[0067] Example 3

[0068] The solvent-free ultrafine high thermal conductivity insulating coating provided in Example 3 of this invention comprises the following components in parts by weight:

[0069] 33 parts solvent-free epoxy resin (epoxy equivalent 165-173 g / eq), 5 parts epoxy reactive diluent, 0.5 parts wetting and leveling agent, 3.5 parts dispersant, 0.5 parts defoamer, 10 parts diamond, 30 parts spherical alumina, 25 parts aluminum hydroxide, 15 parts titanium dioxide, and 18.5 parts reactive polyamide resin (amine equivalent 95).

[0070] In this Example 3, the surface treatment method for the inorganic filler powder (diamond with a particle size of 400 nm, spherical alumina with a particle size of 500 nm, aluminum hydroxide with a particle size of 1800 nm, and titanium dioxide with a particle size of 400 nm) is the same as that in Example 1. The difference is that the weight proportions of diamond, spherical alumina, aluminum hydroxide, and titanium dioxide in the inorganic filler powder are different from those in Example 1.

[0071] Furthermore, the preparation method of the coating in Example 3 is the same as that in Example 1.

[0072] Example 4

[0073] The solvent-free ultrafine high thermal conductivity insulating coating provided in Example 4 of this invention comprises the following components in parts by weight:

[0074] 33 parts solvent-free epoxy resin (epoxy equivalent 165-173 g / eq), 5 parts epoxy reactive diluent, 0.5 parts wetting and leveling agent, 3.5 parts dispersant, 0.5 parts defoamer, 5 parts diamond, 10 parts spherical alumina, 18 parts aluminum hydroxide, 6 parts titanium dioxide, and 18.5 parts fatty amine curing agent (amine equivalent 95).

[0075] In this Example 4, the surface treatment method and weight proportions of the inorganic filler powder (diamond, spherical alumina, aluminum hydroxide, and titanium dioxide) are the same as in Example 1. The difference is that the particle sizes of the diamond, spherical alumina, aluminum hydroxide, and titanium dioxide in the inorganic filler powder are different from those in Example 1. Specifically, the particle size of the diamond is 300 nm, the particle size of the spherical alumina powder is 300 nm, the particle size of the aluminum hydroxide powder is 700 nm, and the particle size of the titanium dioxide is 300 nm.

[0076] Example 5

[0077] The solvent-free ultrafine high thermal conductivity insulating coating provided in Example 5 of this invention comprises the following components in parts by weight:

[0078] 33 parts solvent-free epoxy resin (epoxy equivalent 165-173 g / eq), 5 parts epoxy reactive diluent, 0.5 parts wetting and leveling agent, 3.5 parts dispersant, 0.5 parts defoamer, 5 parts diamond, 10 parts spherical alumina, 18 parts aluminum hydroxide, 6 parts titanium dioxide, and 18.5 parts fatty amine curing agent (amine equivalent 95).

[0079] In this Example 5, the surface treatment method and weight proportions of the inorganic filler powder (diamond, spherical alumina, aluminum hydroxide, and titanium dioxide) are the same as in Example 1. The difference is that the particle sizes of the inorganic filler powder, including diamond, spherical alumina, aluminum hydroxide, and titanium dioxide, are different from those in Example 1. Specifically, the particle size of diamond is 500 nm, the particle size of spherical alumina powder is 500 nm, the particle size of aluminum hydroxide powder is 3000 nm, and the particle size of titanium dioxide is 500 nm.

[0080] Example 6

[0081] The solvent-free ultrafine high thermal conductivity insulating coating provided in Example 6 of this invention comprises the following components in parts by weight:

[0082] 33 parts of solvent-free epoxy resin (epoxy equivalent 165-173 g / eq), 5 parts of epoxy reactive diluent, 0.5 parts of wetting and leveling agent, 3.5 parts of dispersant, 0.5 parts of defoamer, 5 parts of diamond, 10 parts of spherical alumina, 18 parts of aluminum hydroxide, 6 parts of titanium dioxide, and 18.5 parts of reactive polyamide resin (amine equivalent 95).

[0083] In this Example 6, the surface treatment method and weight proportions of the inorganic filler powder (diamond, spherical alumina, aluminum hydroxide, and titanium dioxide) are the same as in Example 1. The difference is that the particle sizes of the diamond, spherical alumina, aluminum hydroxide, and titanium dioxide in the inorganic filler powder are different from those in Example 1. Specifically, the particle size of the diamond is 300 nm, the particle size of the spherical alumina powder is 700 nm, the particle size of the aluminum hydroxide powder is 700 nm, and the particle size of the titanium dioxide is 500 nm.

[0084] Example 7

[0085] The solvent-free ultrafine high thermal conductivity insulating coating provided in Example 7 of this invention comprises the following components in parts by weight:

[0086] 33 parts of solvent-free epoxy resin (epoxy equivalent 165-173 g / eq), 5 parts of epoxy reactive diluent, 0.5 parts of wetting and leveling agent, 3.5 parts of dispersant, 0.5 parts of defoamer, 5 parts of diamond, 10 parts of spherical alumina, 18 parts of aluminum hydroxide, 6 parts of titanium dioxide, and 18.5 parts of reactive polyamide resin (amine equivalent 95).

[0087] In this Example 7, the surface treatment method and weight proportions of the inorganic filler powder (diamond, spherical alumina, aluminum hydroxide, and titanium dioxide) are the same as in Example 1. The difference is that the particle sizes of the diamond, spherical alumina, aluminum hydroxide, and titanium dioxide in the inorganic filler powder are different from those in Example 1. Specifically, the particle size of diamond is 500 nm, the particle size of spherical alumina powder is 300 nm, the particle size of aluminum hydroxide powder is 3000 nm, and the particle size of titanium dioxide is 300 nm.

[0088] Table 1 shows the weight parts of each component in the solvent-free ultrafine high thermal conductivity insulating coatings obtained in Examples 1-3 of this paper.

[0089]

[0090]

[0091] The following is a comparative example.

[0092] Comparative Example 1:

[0093] In this Comparative Example 1, except that the resin film-forming composition used is an aqueous epoxy resin, everything else is the same as in Example 1;

[0094] The following components are included: 33 parts of Hansen waterborne epoxy resin 6562A, 5 parts of epoxy reactive diluent, 0.5 parts of wetting and leveling agent, 3.5 parts of dispersant, 0.5 parts of defoamer, 5 parts of diamond, 10 parts of spherical alumina, 18 parts of aluminum hydroxide, 6 parts of titanium dioxide, and 23 parts of Hansen modified polyamide curing agent 6870-W-53.

[0095] Furthermore, the surface treatment method for inorganic filler powders (diamond, spherical alumina, aluminum hydroxide, titanium dioxide) in Comparative Example 1 is the same as that in Example 1; the preparation method for the coating in Comparative Example 1 is also the same as that in Example 1.

[0096] Comparative Example 2

[0097] In this embodiment, except that the inorganic filler powder was not surface-treated, everything else is the same as in Example 1.

[0098] 33 parts solvent-free epoxy resin (epoxy equivalent 165-173 g / eq), 5 parts epoxy reactive diluent, 0.5 parts wetting and leveling agent, 3.5 parts dispersant, 0.5 parts defoamer, 5 parts diamond, 10 parts spherical alumina, 18 parts aluminum hydroxide, 6 parts titanium dioxide, and 18.5 parts reactive polyamide resin (amine equivalent 95).

[0099] Furthermore, the preparation method of the coating in Comparative Example 1 is the same as that in Example 1.

[0100] Comparative Example 3

[0101] In this embodiment, except for the different weight proportions of the inorganic filler powder, everything else is the same as in Example 1.

[0102] 33 parts solvent-free epoxy resin (epoxy equivalent 165-173 g / eq), 5 parts epoxy reactive diluent, 0.5 parts wetting and leveling agent, 3.5 parts dispersant, 0.5 parts defoamer, 1 part diamond, 5 parts spherical alumina, 10 parts aluminum hydroxide, 2 parts titanium dioxide, and 18.5 parts reactive polyamide resin (amine equivalent 95).

[0103] Furthermore, the surface treatment method for inorganic filler powders (diamond, spherical alumina, aluminum hydroxide, titanium dioxide) in Comparative Example 1 is the same as that in Example 1; the preparation method for the coating in Comparative Example 1 is also the same as that in Example 1.

[0104] The following are examples of performance testing.

[0105] To verify the performance of the solvent-free ultrafine high thermal conductivity insulating coating obtained in the embodiments of the present invention, the following experiments and performance tests were conducted on the solvent-free ultrafine high thermal conductivity insulating coating obtained in Example 1:

[0106] 1. The cured battery compartment workpiece is cured at a temperature of 80 °C for 2 hours;

[0107] It should be noted that after spraying the coating on the battery compartment workpiece, the dry film thickness formed needs to be controlled between 100 - 130 μm. If the film thickness is less than 100 μm, it is difficult to ensure the withstand voltage performance of the paint film for long-term use. If the film thickness is greater than 130 μm, it will cause great waste of the coating and have an adverse effect of increasing the vehicle body weight; the dry film thickness used in the following tests is 120 μm.

[0108] There is no special restriction on the spraying process, and electrostatic spray guns, air spraying, airless spraying, etc. can be used.

[0109] 2. Product performance testing

[0110] 1) Adhesion test

[0111] The test is carried out according to the method specified in GB / T 9826. 100 / 100 means that 10 * 10 grids are drawn on the coating, and after testing, none of the 100 grids have coating peeling off.

[0112] 2) Insulation resistance test:

[0113] The test is carried out according to the provisions of GB / T18384.3 - 2020, using Fluke F1535 for testing, with the requirements of DC1000V and insulation resistance ≥ 500MΩ.

[0114] 3) Withstand voltage performance test:

[0115] The test is carried out according to the provisions of GB / T18384.3 - 2020, using Merak RK2670A for testing, with the requirements of DC5000V, lasting for 60S, and leakage current < ၁ mA။

[0116] 4) Salt spray test:

[0117] The dry paint film is immersed in 5% neutral salt water for 500 hours. If there are no blisters or paint peeling on the surface of the dry paint film, it is qualified.

[0118] 5) High and low temperature shock test:

[0119] It is placed at low temperature of -40 °C for 3 hours, at high temperature of 85 °C for 3 hours, and the intermediate conversion time is 8 minutes. This is one test cycle, and 200 cycles are tested. It is required that there is no crack on the surface of the sample.

[0120] 6) High temperature and high humidity storage test:

[0121] It is aged in a constant temperature and humidity test chamber at a temperature of 85 ± 2 °C and a relative humidity of 85 ± 2% for 1,000 hours. It is required that there is no crack on the surface of the sample.

[0122] 7) Thermal conductivity test: Taiwan Ruiling LW-9389 was used to test the standard test method of thermal conductivity of thermally conductive insulating materials according to ASTM D5470-2017.

[0123] Furthermore, the methods used for performance testing of the coatings obtained in Examples 2, 3, Comparative Examples 1, 2, and 3 of this invention are the same as those used for performance testing of the coating obtained in Example 1 of this invention. Table 2 shows the performance test results of each coating obtained in Examples 1-3 and Comparative Examples 1-3.

[0124]

[0125]

[0126] Based on the data in Table 2 above, and combining the performance of the coatings obtained in Examples 1-3, the performance of the coatings obtained in Comparative Example 1, Comparative Example 2, and Comparative Example 3 respectively can be analyzed to conclude that:

[0127] Because waterborne epoxy resin was used in Comparative Example 1, and waterborne epoxy resin contains a lot of ionic groups, a breakdown problem occurred during the withstand voltage test, which has a great impact on high insulation performance.

[0128] Because the surface of the inorganic filler powder was not treated in Comparative Example 2, it was difficult for diamond, spherical alumina, aluminum hydroxide and titanium dioxide to be evenly dispersed in the system, which could easily lead to some parts lacking inorganic powder, resulting in uneven insulation performance.

[0129] Because the content of insulating powder in Comparative Example 3 is lower than that in Examples 1-3, the obtained coating cannot meet the insulation and thermal conductivity requirements of the embodiments of the present invention.

[0130] In summary, only the coating obtained using the formula of this invention is fine, possessing not only high thermal conductivity and high insulation properties, but also reduced heat radiation and increased thermal conductivity, thus well meeting the needs of vehicle power batteries and laying a solid foundation for improving the safety of vehicle power batteries. In addition, the preparation method of this invention is simple, and the raw materials are readily available, making it very suitable for mass production and worthy of widespread promotion and use.

[0131] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A solvent-free, ultrafine, high thermal conductivity insulating coating, characterized in that, The coating comprises 30–50 wt of resin film-forming composition, 10–20 wt of epoxy reactive diluent, 0.3–1.3 wt of wetting and leveling agent, 2–5 wt of dispersant, 0.5–1 wt of defoamer, 16–20 wt of curing agent, and 40–70 wt of inorganic filler; wherein the inorganic filler comprises 3–10 wt of diamond powder, 10–30 wt of spherical alumina powder, 15–25 wt of aluminum hydroxide powder, and 5–15 wt of titanium dioxide.

2. The solvent-free ultrafine high thermal conductivity insulating coating according to claim 1, characterized in that, The diamond powder has a particle size of 300–500 nm; the spherical alumina powder has a particle size of 300–700 nm; the aluminum hydroxide powder has a particle size of 700–3000 nm; and the titanium dioxide has a particle size of 300–500 nm.

3. A solvent-free ultrafine high thermal conductivity insulating coating according to claim 1 or 2, characterized in that, The resin film-forming composition is selected from at least one of polyurethane resin, acrylic resin, and epoxy resin; the curing agent is at least one of reactive polyamide resin curing agent, aliphatic amine curing agent, and cycloaliphatic amine curing agent; the wetting and leveling agent is selected from one or more of BYK302, BYK378, BYK325, BYK331, UNIQFLOW375S, and Efka SL3239 used in combination; the dispersant is selected from one or more of BYK110, BYK163, BYK168, EfkaFA4611, BYK9076, and BYK2009 used in combination; the defoamer is selected from one or more of Shin-Etsu KSZ-108, Dow Corning ACP-1400, BYK-066N, and BYK-530A used in combination.

4. The solvent-free ultrafine high thermal conductivity insulating coating according to claim 3, characterized in that, The diamond powder, spherical alumina powder, aluminum hydroxide powder, and titanium dioxide in the inorganic filler have all undergone surface treatment. The specific treatment method is any one of dry modification, wet modification, or gas-phase modification. The wet modification method is as follows: take an aqueous solution of KH570 with a mass fraction of 2-8% silane coupling agent, adjust the pH value to 3-5 with oxalic acid, and keep it at room temperature for 30-60 minutes to allow the silane coupling agent to be fully hydrolyzed; heat each powder component in the inorganic filler to 30-70°C, and spray the above-mentioned coupling agent aqueous solution. After complete wetting, keep it for 2-6 hours, vacuum dry at 50-70°C for 20-30 hours, sieve and classify, and wait for use.

5. The solvent-free ultrafine high thermal conductivity insulating coating according to claim 4, characterized in that, The volume resistivity of this solvent-free, ultrafine, high thermal conductivity insulating coating is ≥1000MΩ; the leakage current is <1mA.

6. A method for preparing a solvent-free ultrafine high thermal conductivity insulating coating according to any one of claims 1-5, characterized in that, The method specifically includes the following steps: S1. Weigh out the following components according to the specified quantities: 30-50% wt epoxy film-forming composition, 10-20% epoxy reactive diluent, 0.3-1.3% wt wetting and leveling agent, 2-5% wt dispersant, 0.5-1% wt defoamer, and 40-70% wt inorganic filler; wherein the inorganic filler includes 3-10% wt diamond powder, 10-30% wt spherical alumina powder, 15-25% wt aluminum hydroxide powder, and 5-15% wt titanium dioxide. S2. The weighed epoxy reactive diluent, wetting and leveling agent and dispersant are added to the epoxy film-forming composition in sequence while stirring to carry out slow dispersion treatment, so as to obtain an intermediate mixture after slow dispersion. S3. Add the defoamer and inorganic filler to the dispersed intermediate mixture while stirring, and then perform medium-speed dispersion treatment to obtain the medium-speed dispersed intermediate mixture. S4. Transfer the intermediate mixture after medium-speed dispersion to a sand mill, select zirconium beads of 0.3-0.4 mm, and grind until the fineness is less than 5 μm to obtain the coating precursor; S5. Add the curing agent to the coating precursor while stirring, and stir to obtain a solvent-free ultrafine high thermal conductivity insulating coating.

7. The method for preparing the solvent-free ultrafine high thermal conductivity insulating coating according to claim 6, characterized in that, The stirring rate during the slow dispersion process in S2 is 400-500 rpm, and the stirring time is 2-5 min.

8. The method for preparing the solvent-free ultrafine high thermal conductivity insulating coating according to claim 6, characterized in that, The stirring rate during the medium-speed dispersion process in S3 is 800–1500 rpm, and the stirring time is 5–30 min.

9. The method for preparing the solvent-free ultrafine high thermal conductivity insulating coating according to claim 6, characterized in that, In step S5, the stirring rate is 500-600 rpm and the stirring time is 8-15 min.

10. The application of the solvent-free ultrafine high thermal conductivity insulating coating according to any one of claims 1-5 in the battery compartment of a lithium battery for a new energy vehicle.

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