High-thermal-conductivity environment-friendly modified polyurethane release agent and preparation method thereof

Abstract

The invention relates to the technical field of release agents, in particular to a high-thermal-conductivity environment-friendly modified polyurethane release agent and a preparation method thereof.The high-thermal-conductivity environment-friendly modified polyurethane release agent is prepared by taking epoxy modified quaternary ammonium salt waterborne polyurethane emulsion as a main component and matching with a ternary composite thermal conductive filler, an environment-friendly silane coupling agent, a VOC-free polyurethane thickener, a plant-based defoaming agent and an environment-friendly anti-migration agent. The balance is deionized water; all the components have a synergistic effect, high thermal conductivity, environment friendliness and excellent demolding performance and stability are considered, and the mold is suitable for molding of various high-end polyurethane products. The cleaning agent is environment-friendly and harmless, and traditional solvent type components are abandoned; an efficient heat-conducting network is constructed, and the product quality problem is avoided; film forming is uniform, demoulding is smooth and residue-free, and the service life of the mould is prolonged; the dispersion and stability are good, the temperature and acid and alkali resistance is realized, and the application range is wide.

Description

Technical Field

[0001] This invention relates to the field of mold release agent technology, specifically to a high thermal conductivity, environmentally friendly modified polyurethane mold release agent and its preparation method. Background Technology

[0002] Polyurethane materials are widely used in construction, automotive, electronics, and furniture industries due to their excellent mechanical properties, thermal insulation, and molding adaptability. Mold release agents, as key additives in the molding process of polyurethane products, directly affect the surface quality of the product, molding efficiency, and mold lifespan. Traditional polyurethane mold release agents are mainly divided into three categories: solvent-based, oil-based, and water-based. While solvent-based mold release agents offer excellent release effects, their high VOC emissions not only pollute the environment but also harm the health of operators, failing to comply with current environmental regulations and green production concepts. Oil-based mold release agents suffer from problems such as excessive residue, easy contamination of the product surface, and reduced adhesion of subsequent coatings, limiting their application in high-end products.

[0003] Waterborne polyurethane release agents have become the mainstream due to their environmental and safety advantages. However, existing waterborne products generally suffer from insufficient thermal conductivity. During the molding process of polyurethane products, the exothermic reaction is difficult to dissipate quickly, easily leading to uneven internal temperature and quality problems such as shrinkage cavities, deformation, and internal stress concentration. This is especially significant for the molding of large and complex structures. To improve thermal conductivity, existing technologies often use single thermally conductive fillers such as aluminum nitride and boron nitride for modification. However, single fillers suffer from poor dispersibility and insufficient compatibility with the polyurethane matrix, easily leading to agglomeration. This not only fails to effectively build a thermally conductive network but also disrupts the film-forming continuity of the release agent, resulting in increased release force and mold residue.

[0004] Meanwhile, existing water-based release agents suffer from limited functionality, failing to simultaneously achieve environmental friendliness, high thermal conductivity, excellent release performance, and long-term stability. Some modified products sacrifice smooth release to improve thermal conductivity, or due to poor compatibility between fillers and the matrix, the release agent may experience stratification or precipitation during storage, requiring repeated stirring during use and affecting construction efficiency. Furthermore, existing release agents lack sufficient anti-migration properties, and after long-term use, fillers are prone to precipitating from the film layer, reducing the number of times the release agent can be reused and potentially contaminating the product surface, increasing subsequent processing costs. Therefore, developing a modified polyurethane release agent that combines high thermal conductivity, environmental friendliness, excellent release performance, and stability is key to solving current industry pain points and is of great significance for promoting the development of the polyurethane products industry towards high efficiency, greenness, and high-end products. Summary of the Invention

[0005] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a high thermal conductivity, environmentally friendly modified polyurethane release agent and its preparation method.

[0006] (II) Technical Solution A high thermal conductivity and environmentally friendly modified polyurethane release agent, comprising the following components by mass percentage: 38-42% epoxy-modified quaternary ammonium salt hydrochloric polyurethane emulsion, 8-12% ternary composite thermally conductive filler, 1.8-2.2% environmentally friendly silane coupling agent, 1.2-1.8% VOC-free polyurethane thickener, 0.3-0.5% plant-based defoamer, 0.5-1% environmentally friendly anti-migration agent, and deionized water to make up to 100%.

[0007] Preferably, the epoxy-modified quaternary ammonium salt hydrochloric polyurethane emulsion is prepared by stepwise polymerization of isophorone diisocyanate, polybutylene adipate diol, N-methyldiethanolamine, and epichlorohydrin, with a solid content of 45-48%, an epoxy value of 0.05-0.08 eq / 100g, a number average molecular weight of 20,000-30,000, and a molecular weight distribution index of 1.2-1.5.

[0008] Preferably, the ternary composite thermally conductive filler is composed of nanocrystalline aluminum nitride, silane-modified boron nitride / graphene composite, and nano-silicon carbide in a mass ratio of 1:2:0.5. The nanocrystalline aluminum nitride has a particle size of 60-80 nm, the silane-modified boron nitride / graphene composite has a boron nitride to graphene mass ratio of 2:1 and is grafted with KH-570, and the nano-silicon carbide has a particle size of 30-50 nm. The KH-570 grafting rate of the silane-modified boron nitride / graphene composite is 8-12%, and the specific surface area is ≥50 m². 2 / g.

[0009] Preferably, the environmentally friendly anti-migration agent is polylactic acid-grafted polyethylene glycol copolymer with a number average molecular weight of 5000-8000, a glass transition temperature of 55-65℃, and a thermal decomposition temperature of ≥300℃.

[0010] Preferably, the thermal conductivity of nano-silicon carbide is 120-150 W / (m·K), and the resistivity is ≥10. 16 After surface modification with γ-aminopropyltriethoxysilane, the water contact angle is ≤30°, the oil absorption value is ≤20mL / 100g, and the dispersion stability is ≥96h.

[0011] Preferably, the VOC-free polyurethane thickener is a VOC-free nonionic associative polyurethane thickener; the plant-based defoamer is a polyether-modified tea saponin defoamer.

[0012] Preferably, the preparation method of the high thermal conductivity environmentally friendly modified polyurethane release agent includes the following steps: S1. Pretreatment of ternary composite thermally conductive filler: Nanocrystalline aluminum nitride, silane-modified boron nitride / graphene composite, and nano-silicon carbide are mixed in proportion and subjected to plasma treatment under an argon atmosphere for 10-15 min with a plasma power of 800-1000W. Then, deionized water is added to prepare a suspension with a mass fraction of 12-14%. The suspension is ultrasonically dispersed at a power of 350-450W for 25-35 min. An environmentally friendly silane coupling agent is added, and the mixture is stirred at 350-450r / min for 1.2-1.8 h at 62-68℃ to obtain a modified thermally conductive filler dispersion. S2. Preparation of epoxy-modified quaternary ammonium salt hydrochloric polyurethane emulsion: Polybutylene adipate diol was vacuum dehydrated at 100-110℃ for 2-3h, cooled to 60-65℃ and added isophorone diisocyanate, reacted at 75-80℃ for 2-2.5h, N-methyldiethanolamine was added and reacted for 1-1.5h, cooled to 40-45℃ and added epichlorohydrin, reacted at 50-55℃ for 1.5-2h, neutralized to pH 7.0-7.5 with triethanolamine and then emulsified with water to obtain the emulsion; S3. Composite modification: Add the emulsion obtained in step S2 to the reaction vessel, stir at 850-950 r / min for 35-40 min at 58-62℃, adjust the pH to 7.8-8.2, and dropwise add the dispersion from step S1 at a rate of 5-8 mL / min. After the addition is complete, raise the temperature to 70-80℃ and shear disperse at 1400-1600 r / min for 45-55 min. During this period, the particle size is detected by a laser particle size analyzer every 15 min to ensure that D90≤1.5μm. S4. Additives and Curing: Add VOC-free nonionic associative polyurethane thickener, polyether-modified tea saponin defoamer, and environmentally friendly anti-migration agent in sequence. Stir at 600-700 r / min for 18-22 min at 62-68℃, cool to 25-30℃, and cure for 20-22 h. During this period, stir at 250-300 r / min for 10 min every 6 h. Filter through 250-280 mesh filter cloth to obtain the release agent.

[0013] Preferably, in step S2, the molar ratio of isophorone diisocyanate to polybutylene adipate diol is 1.8:1-2.2:1, the amount of N-methyldiethanolamine added is 8-12% of the mass of polybutylene adipate diol, the amount of epichlorohydrin added is 5-8% of the total mass of the reaction system, and the stirring speed during emulsification is 1200-1500 r / min, and the emulsification time is 20-30 min.

[0014] Preferably, in step S3, a gradient heating strategy is adopted during high-speed shear dispersion, with the temperature increased by 5°C every 10 minutes to the target temperature. During the droplet addition process, the temperature fluctuation of the system is kept ≤±2°C by a constant temperature jacket. After the high-speed shear is completed, the system is kept at the temperature and stirred for 30 minutes at a stirring speed of 800 r / min.

[0015] Preferably, the curing environment in step S4 is a clean, dust-free space with humidity controlled at 40-60%. The filtered release agent must be tested by a laser particle size analyzer to ensure that the particle size distribution span is ≤1.2 and the thermal conductivity is tested by a thermal conductivity meter to ensure that it is ≥1.5 W / (m·K). Only after passing the tests can it be packaged. The packaging container is a light-proof polyethylene drum, sealed and stored at a temperature of 5-35℃.

[0016] (iii) Beneficial technical effects Compared with existing technologies, the beneficial effects of this invention are: 1. This invention uses epoxy-modified quaternary ammonium salt hydrochloric polyurethane emulsion as the matrix, combined with VOC-free additives and plant-based defoamers, completely eliminating traditional solvent-based components, reducing pollutant emissions from the source, complying with environmental regulations and green production requirements, while having excellent biocompatibility, posing no harm to the environment and operators, and its application scenarios are not subject to environmental restrictions.

[0017] 2. Through the synergistic effect of ternary composite thermally conductive fillers, a highly efficient and continuous thermally conductive network is constructed. Compared with products modified with single fillers, the thermal conductivity is greatly improved, which can quickly conduct the reaction heat generated during polyurethane molding, avoid quality problems such as shrinkage cavities and deformation caused by uneven temperature, and significantly improve the molding accuracy and pass rate of products.

[0018] 3. The epoxy-modified quaternary ammonium salt hydrochloric polyurethane emulsion has good compatibility with the composite thermally conductive filler, forms a uniform and dense film, and ensures a smooth demolding process with minimal mold residue. This not only guarantees the cleanliness of the product surface, eliminating the need for subsequent cleaning processes, but also reduces mold release agent consumption, significantly increases the number of repeated demolding cycles, and lowers production costs. At the same time, the film layer has moderate adhesion after formation, preventing it from sticking to the product or causing mold wear due to detachment, thus extending the mold's service life.

[0019] 4. Through plasma pretreatment and silane coupling agent modification, the dispersion uniformity of the composite thermally conductive filler in the aqueous system is significantly improved. In addition, the addition of environmentally friendly anti-migration agent effectively inhibits filler migration and precipitation, so that the release agent does not have stratification or precipitation during storage and has excellent stability at room temperature. Moreover, the release agent has good temperature resistance and acid and alkali resistance, adapts to the use requirements of different environments, has a wide range of applications, and can meet the molding requirements of high-end polyurethane products in multiple fields such as construction, automobiles, and electronics. Attached Figure Description

[0020] Figure 1This is a process flow diagram of a method for preparing a high thermal conductivity and environmentally friendly modified polyurethane release agent disclosed in this invention; Figure 2 This is a comparison chart of thermal conductivity, particle size distribution range, and D90 line between the examples and the comparative examples; Figure 3 This is a bar graph comparing the demolding force and the number of repeated demolding cycles in the examples and comparative examples; Figure 4 This is a radar comparison chart created by standardizing the dimensions of the performance comparison data of the examples and comparative examples. Detailed Implementation

[0021] according to Figures 1 to 4 The specific embodiments of the present invention are as follows: The following detailed description of the high thermal conductivity and environmentally friendly modified polyurethane release agent of the present invention and its preparation method, in conjunction with examples and comparative examples, is provided below; all raw materials used in the examples are commercially available qualified products.

[0022] Example 1 1. Raw material composition and parameters (by mass percentage) Epoxy-modified quaternary ammonium salt hydrochloric polyurethane emulsion: 40%. Prepared by stepwise polymerization of isophorone diisocyanate (99.5% purity), polybutylene adipate diol (2000 number-average molecular weight), N-methyldiethanolamine (99% purity), and epichlorohydrin (99% purity). Solid content: 46.5%, epoxy value: 0.065 eq / 100g, number-average molecular weight: 25000, molecular weight distribution index: 1.35.

[0023] Ternary composite thermally conductive filler: 10%. Compounded in a mass ratio of 1:2:0.5, including nanocrystalline aluminum nitride with a particle size of 70nm and a purity of 99.8%, and a silane-modified boron nitride / graphene composite with a boron nitride to graphene mass ratio of 2:1, grafted with KH-570 at a grafting rate of 10%, and a specific surface area of ​​55m². 2 / g, nano-silicon carbide particles with a diameter of 40nm, thermal conductivity of 135W / (m・K), resistivity of 1.2×10⁻⁶ 17 Ω・cm Surface modified with γ-aminopropyltriethoxysilane, water contact angle 25°, oil absorption value 18mL / 100g, dispersion stability 100h.

[0024] Environmentally friendly silane coupling agent: 2.0%. KH-550 with 98% purity and no VOC residue is selected.

[0025] VOC-free polyurethane thickener: 1.5%. This is a VOC-free nonionic associative polyurethane thickener.

[0026] Plant-based defoamer: 0.4%. This is a polyether-modified tea saponin defoamer with a solid content of 30%.

[0027] Environmentally friendly anti-migration agent: 0.8%. It is a polylactic acid-grafted polyethylene glycol copolymer with a number average molecular weight of 6500, a glass transition temperature of 60℃, and a thermal decomposition temperature of 320℃.

[0028] Deionized water: 35.3% to bring the total to 100%.

[0029] 2. Preparation method S1. Pretreatment of ternary composite thermally conductive filler Accurately weigh 2.0 kg of nanocrystalline aluminum nitride, 4.0 kg of silane-modified boron nitride / graphene composite, and 1.0 kg of nano-silicon carbide, mix thoroughly, and place in a plasma treatment device. High-purity argon gas (99.99% purity) is introduced to purge air. The plasma power is set to 900 W, and treatment is continued for 12 min. After treatment, the mixed filler is added to 43.0 kg of deionized water and stirred to prepare a suspension with a mass fraction of 12.5%. This suspension is then transferred to an ultrasonic disperser, with an ultrasonic power set to 400 W. During dispersion for 30 min, the mixture is stirred for 1 min every 5 min to prevent local agglomeration. The suspension is then transferred to a 50 L reactor, and 1.2 kg of environmentally friendly silane coupling agent KH-550 is added. The temperature is raised to 65 °C, and the stirring speed is adjusted to 400 r / min. The mixture is stirred at a constant temperature for 1.5 h, and samples are taken every 20 min to ensure no significant sedimentation. After the reaction, a uniform modified thermally conductive filler dispersion is obtained and sealed for later use.

[0030] S2. Preparation of epoxy-modified quaternary ammonium salt-based polyurethane emulsion Weigh 50.0 kg of polybutylene adipate diol and place it in a 100 L vacuum drying reactor. Set the temperature to 105℃ and the vacuum degree to -0.095 MPa, and dehydrate under vacuum for 2.5 h until the moisture content is ≤0.1%. Then, cool the reactor to 62℃. Slowly add 34.8 kg of isophorone diisocyanate to the reactor at a molar ratio of 2.0:1. Raise the temperature to 78℃ and react at this temperature for 2.2 h. After the -NCO group content is reduced to approximately 3.2% (the theoretical value) by infrared spectroscopy, add 5.0 kg of N-methyldiethanolamine (10% of the mass of polybutylene adipate diol) and continue the reaction for another 1.2 h. After the reaction was complete, the temperature was lowered to 42℃, and 7.6 kg of epichlorohydrin was slowly added dropwise, accounting for 6.5% of the total mass of the reaction system. The addition rate was controlled at 3 mL / min. After the addition was complete, the temperature was raised to 52℃ and the reaction was maintained at this temperature for 1.8 h. Subsequently, triethanolamine was added for neutralization, and the pH of the system was adjusted to 7.2. Then, 85.0 kg of deionized water was added, and the stirring speed was set to 1300 r / min. Emulsification was carried out for 25 min to obtain an epoxy-modified quaternary ammonium salt aqueous polyurethane emulsion with a solid content of 46.5%, which was then set aside for later use.

[0031] S3. Composite Modification 240.0 kg of the emulsion obtained in step S2 was added to a 200 L reactor, heated to 60 °C, and stirred at 900 r / min for 38 min. The pH of the system was adjusted to 8.0 with a 5% (w / w) triethanolamine solution. 37.2 kg of the modified thermally conductive filler dispersion prepared in step S1 was added dropwise at a rate of 6 mL / min using a metering pump. During the addition, the temperature fluctuation of the system was controlled to ≤±1 °C using a constant temperature jacket to prevent uneven local reaction. After the addition was completed, a gradient temperature program was started: initial temperature 60 °C, increasing by 5 °C every 10 min, reaching 70 °C after 20 min, and then holding for 10 min to reach the target temperature of 75 °C. The high-speed shearing equipment was turned on and the rotation speed was set to 1500 r / min. During the 50-minute high-speed shearing dispersion, the particle size distribution was checked every 15 minutes using a laser particle size analyzer. The first measurement showed D90 = 1.4 μm, the second D90 = 1.2 μm, and the third D90 = 1.1 μm, all meeting the requirement of D90 ≤ 1.5 μm. After the high-speed shearing was completed, the stirring speed was adjusted to 800 r / min, and the mixture was kept at the same temperature and stirred for 30 minutes to ensure that the thermally conductive filler and the emulsion were fully combined.

[0032] S4. Additives and Curing Add 0.9 kg of VOC-free nonionic associative polyurethane thickener, 0.24 kg of polyether-modified tea saponin defoamer, and 0.48 kg of polylactic acid-grafted polyethylene glycol copolymer anti-migration agent sequentially to the reactor. Maintain the system temperature at 65°C and set the stirring speed to 650 r / min, stirring at this constant temperature for 20 min to ensure uniform dispersion of the additives. After stirring, cool the system to 28°C using a cooling system and transfer it to a clean, dust-free curing workshop with humidity controlled at 50% and air cleanliness Class 1000. During the 21-hour curing period, start the stirring device every 6 hours, setting the speed to 280 r / min and stirring for 10 min to prevent stratification. After curing, filter the material through a 260-mesh filter cloth to remove a small amount of mechanical impurities, obtaining the finished release agent. Testing of the finished product showed that the particle size distribution span = 1.0 and the thermal conductivity = 1.8 W / (m·K) both meet the standards defined in the claims. Pack the finished product into a 20L light-proof polyethylene drum, seal it, and store it in a cool, ventilated place at 25℃.

[0033] Example 2 1. Raw material composition and parameters (by mass percentage) Epoxy-modified quaternary ammonium salt hydrochloric polyurethane emulsion: 38%. Prepared by stepwise polymerization of isophorone diisocyanate (99.5% purity), polybutylene adipate diol (number average molecular weight 1800), N-methyldiethanolamine (99% purity), and epichlorohydrin (99% purity). Solid content: 45%, epoxy value: 0.055 eq / 100g, number average molecular weight: 22000, molecular weight distribution index: 1.25.

[0034] Ternary composite thermally conductive filler: 8%. Compounded in a mass ratio of 1:2:0.5, including nanocrystalline aluminum nitride with a particle size of 60nm and a purity of 99.8%, and a silane-modified boron nitride / graphene composite with a boron nitride to graphene mass ratio of 2:1, grafted with KH-570 at a grafting rate of 8% and a specific surface area of ​​50m². 2 / g, nano-silicon carbide particles 30nm in size, thermal conductivity 120W / (m・K), resistivity 1.0×10⁻⁶ 16 The Ω·cm dispersion with γ-aminopropyltriethoxysilane surface modification has a water contact angle of 28°, an oil absorption value of 19 mL / 100 g, and a dispersion stability of 96 h.

[0035] Environmentally friendly silane coupling agent: 1.8%. KH-550 with a purity of 98% was selected.

[0036] VOC-free polyurethane thickener: 1.2%. This is a VOC-free nonionic associative polyurethane thickener.

[0037] Plant-based defoamer: 0.3%. This is a polyether-modified tea saponin defoamer with a solid content of 30%.

[0038] Environmentally friendly anti-migration agent: 0.5%. It is a polylactic acid-grafted polyethylene glycol copolymer with a number average molecular weight of 5000, a glass transition temperature of 55℃, and a thermal decomposition temperature of 300℃.

[0039] Deionized water: 50.2% to bring the total to 100%.

[0040] 2. Preparation method S1. Pretreatment of ternary composite thermally conductive filler Weigh 1.6 kg of nanocrystalline aluminum nitride, 3.2 kg of silane-modified boron nitride / graphene composite, and 0.8 kg of nano-silicon carbide, mix thoroughly, and place in a plasma treatment device. Under an argon atmosphere, set the power to 800 W and treat for 10 min. After treatment, add 42.1 kg of deionized water and stir to prepare a 12% (w / w) suspension. Transfer the suspension to an ultrasonic disperser and disperse at 350 W for 25 min. Transfer the suspension to a 50 L reactor, add 1.26 kg of environmentally friendly silane coupling agent, heat to 62 °C, stir at 350 r / min, and react at a constant temperature for 1.2 h to obtain a modified thermally conductive filler dispersion for later use.

[0041] S2. Preparation of epoxy-modified quaternary ammonium salt-based polyurethane emulsion Weigh 45.0 kg of polybutylene adipate diol and place it in a 100 L vacuum reactor. Dehydrate under vacuum at 100℃ and -0.09 MPa for 2 hours, then cool to 60℃. Add 29.5 kg of isophorone diisocyanate (molar ratio of isophorone diisocyanate to polybutylene adipate diol: 1.8:1). Heat to 75℃ and react for 2 hours. After confirming the -NCO group content meets the standard, add 3.6 kg of N-methyldiethanolamine (8% of the mass of polybutylene adipate diol) and react for 1 hour. Cool to 40℃ and add 5.1 kg of epichlorohydrin (5% of the total mass of the reaction system). Heat to 50℃ and react for 1.5 hours. Neutralize to pH 7.0 with triethanolamine, add 78.0 kg of deionized water, and emulsify at 1200 rpm for 20 minutes to obtain an emulsion with a solid content of 45%. Set aside for later use.

[0042] S3. Composite Modification 266.7 kg of emulsion was added to a 200 L reactor, heated to 58 °C, and stirred at 850 rpm for 35 min. The pH was adjusted to 7.8, and 47.7 kg of modified thermally conductive filler dispersion was added dropwise at a rate of 5 mL / min. After the addition was complete, a gradient temperature increase was initiated: 58 °C for 10 min, then increased to 63 °C for 20 min, then increased to 68 °C for 30 min, and finally increased to the target temperature of 73 °C. A high-speed shearing speed of 1400 rpm was set. During the 45 min dispersion period, the D90 values ​​were measured to be 1.3 μm, 1.2 μm, and 1.1 μm, respectively. After shearing, the mixture was stirred at 800 rpm for 30 min.

[0043] S4. Additives and Curing Add 0.84 kg of VOC-free nonionic associative polyurethane thickener, 0.21 kg of polyether-modified tea saponin defoamer, and 0.35 kg of polylactic acid-grafted polyethylene glycol copolymer anti-migration agent sequentially. Stir at 62℃ and 600 rpm for 18 min. Cool to 25℃ and transfer to a curing workshop with 40% humidity. During curing for 20 hours, stir at 250 rpm for 10 min every 6 hours. After filtration through a 250-mesh filter cloth, the particle size distribution span is measured to be 1.1 and the thermal conductivity is 1.5 W / (m·K). If qualified, seal in a light-proof polyethylene drum and store at 5℃.

[0044] Example 3 1. Raw material composition and parameters (by mass percentage) Epoxy-modified quaternary ammonium salt hydrochloric polyurethane emulsion: 42%. Prepared by stepwise polymerization of isophorone diisocyanate (99.5% purity), polybutylene adipate diol (2200 number-average molecular weight), N-methyldiethanolamine (99% purity), and epichlorohydrin (99% purity). Solid content: 48%, epoxy value: 0.075 eq / 100g, number-average molecular weight: 28000, molecular weight distribution index: 1.45.

[0045] Ternary composite thermally conductive filler: 12%. Compounded in a mass ratio of 1:2:0.5, including nanocrystalline aluminum nitride with a particle size of 80nm and a purity of 99.8%, and a silane-modified boron nitride / graphene composite with a boron nitride to graphene mass ratio of 2:1, grafted with KH-570 at a grafting rate of 12%, and a specific surface area of ​​60m². 2 / g, nano-silicon carbide particles with a diameter of 50nm, thermal conductivity of 150W / (m・K), resistivity of 1.5×10⁻⁶ 17 The Ω·cm surface-modified with γ-aminopropyltriethoxysilane has a water contact angle of 22°, an oil absorption value of 16 mL / 100 g, and a dispersion stability of 105 h.

[0046] Environmentally friendly silane coupling agent: 2.2%. KH-550 with a purity of 98% was selected.

[0047] VOC-free polyurethane thickener: 1.8%. This is a VOC-free nonionic associative polyurethane thickener.

[0048] Plant-based defoamer: 0.5%. This is a polyether-modified tea saponin defoamer with a solid content of 30%.

[0049] Environmentally friendly anti-migration agent: 1.0%. It is a polylactic acid-grafted polyethylene glycol copolymer with a number average molecular weight of 8000, a glass transition temperature of 65℃, and a thermal decomposition temperature of 330℃.

[0050] Deionized water: 39.5% to bring the total to 100%.

[0051] 2. Preparation method S1. Pretreatment of ternary composite thermally conductive filler Weigh 2.4 kg of nanocrystalline aluminum nitride, 4.8 kg of silane-modified boron nitride / graphene composite, and 1.2 kg of nano-silicon carbide, mix them, and place them in a plasma device. Under an argon atmosphere, process at 1000 W for 15 min. Add 51.6 kg of deionized water to prepare a 14% (w / w) suspension, and ultrasonically disperse at 450 W for 35 min. Transfer to a reactor, add 1.54 kg of environmentally friendly silane coupling agent, and stir at 68℃ and 450 rpm for 1.8 h to obtain a modified thermally conductive filler dispersion for later use.

[0052] S2. Preparation of epoxy-modified quaternary ammonium salt-based polyurethane emulsion Weigh 55.0 kg of polybutylene adipate diol and dehydrate it under vacuum at 110℃ and -0.098 MPa for 3 h, then cool it to 65℃. Add 40.2 kg of isophorone diisocyanate (molar ratio of isophorone diisocyanate to polybutylene adipate diol: 2.2:1) and react at 80℃ for 2.5 h. Add 6.6 kg of N-methyldiethanolamine (12% of the mass of polybutylene adipate diol) and react for 1.5 h. Cool to 45℃ and add 9.2 kg of epichlorohydrin (8% of the total mass of the reaction system) dropwise, reacting at 55℃ for 2 h. Neutralize to pH 7.5, add 92.0 kg of deionized water, emulsify at 1500 rpm for 30 min, and check the solid content; it should be 48%. Set aside for later use.

[0053] S3. Composite Modification 294.0 kg of emulsion was added to a 300 L reactor and stirred at 62 °C and 950 rpm for 40 min. The pH was adjusted to 8.2, and 60.0 kg of modified thermally conductive filler dispersion was added dropwise at 8 mL / min. After the addition was complete, the temperature was gradually increased: 62 °C for 10 min, then to 67 °C for 20 min, then to 72 °C for 30 min, then to 77 °C for 40 min, and finally to the target temperature of 80 °C. High-speed shearing was performed at 1600 rpm, and the D90 was measured to be ≤1.0 μm during the 55 min dispersion period. After shearing, the mixture was stirred at 800 rpm for 30 min.

[0054] S4. Additives and Curing Add 1.26 kg of VOC-free nonionic associative polyurethane thickener, 0.35 kg of polyether-modified tea saponin defoamer, and 0.7 kg of polylactic acid-grafted polyethylene glycol copolymer anti-migration agent. Stir at 68°C and 700 rpm for 22 min. Cool to 30°C and mature for 22 h at 60% humidity, stirring at 300 rpm for 10 min every 6 h. Filter through a 280-mesh filter cloth. After passing the tests (particle size distribution span = 0.9, thermal conductivity = 2.1 W / (m·K), seal and store in a ventilated place at 35°C.

[0055] Comparative Example 1. Raw material composition and parameters (by mass percentage) Ordinary waterborne polyurethane emulsion: 40%. Untreated with epoxy modification and quaternization, solid content 45%, number average molecular weight 18000, molecular weight distribution index 1.8.

[0056] Single thermally conductive filler: 10%. Only nanocrystalline aluminum nitride with a particle size of 70nm is selected, without plasma treatment or silane coupling agent modification.

[0057] Common silane coupling agent: 2.0%. KH-560, a non-environmentally friendly type containing trace amounts of VOCs, was selected.

[0058] Conventional polyurethane thickener: 1.5%. Anionic polyurethane thickener containing VOCs.

[0059] Mineral oil defoamer: 0.4%. Mineral oil defoamer containing VOCs.

[0060] No environmentally friendly anti-migration agents.

[0061] Deionized water: 46.1% to bring the total to 100%.

[0062] 2. Preparation method S1. Thermally conductive filler treatment 10.0 kg of nanocrystalline aluminum nitride was directly added to 85.0 kg of deionized water and ultrasonically dispersed at 300 W for 20 min. Then, 2.0 kg of ordinary silane coupling agent KH-560 was added and stirred at 60 °C for 1 h without plasma treatment, resulting in a dispersion with poor stability.

[0063] S2. Preparation of ordinary waterborne polyurethane emulsions Weigh 50.0 kg of polybutylene adipate diol, dehydrate under vacuum at 105 °C for 2.5 h, cool to 62 °C, add 34.8 kg of isophorone diisocyanate, react at 78 °C for 2.2 h. Without adding N-methyldiethanolamine and epichlorohydrin, neutralize directly with triethanolamine to pH 7.2, add 85.0 kg of deionized water for emulsification, and obtain a common waterborne polyurethane emulsion.

[0064] S3. Composite Modification 40.0 kg of ordinary emulsion was added to a 100 L reactor and stirred at 55 °C and 800 r / min for 30 min. 97.0 kg of thermally conductive filler dispersion was added directly without controlling the dripping rate. The temperature was raised to 75 °C and stirred at 800 r / min for 60 min without high-speed shearing or gradient heating. Particle size distribution was not detected.

[0065] S4. Additives and Curing Add 1.5 kg of VOC-containing thickener and 0.4 kg of mineral oil defoamer, stir at 60°C for 15 min, cool to 25°C without controlling ambient humidity (natural humidity approximately 75%), and mature for 12 h. Then filter directly through a 200-mesh filter cloth without testing particle size distribution and thermal conductivity, and directly package and store.

[0066] The basic performance and environmental performance of the examples and comparative examples are compared in the table below: Table 1 Testing items Example 1 Example 2 Example 3 Comparative Example Thermal conductivity [W / (m・K)] 1.8 1.5 2.1 0.7 <![CDATA[VOC content [mg / m 3 > Not detected Not detected Not detected 92 Particle size distribution span 1.0 1.1 0.9 2.5 D90[μm] 1.1 1.2 1.0 3.8 Storage stability (3 months at room temperature) No stratified sedimentation No stratified sedimentation No stratified sedimentation Layering, sedimentation Dispersion stability [h] 102 98 108 45 Water contact angle [°] 26 28 23 48 The application performance and durability of the examples and comparative examples are compared in the table below: Table 2 Testing items Example 1 Example 2 Example 3 Comparative Example Demolding force [N] 8.5 9.3 7.6 26.8 Number of demolding repetitions [times] 52 46 63 12 Mold residue No residue No residue No residue Adhesion residue Packing material precipitation rate (72h) 0.3% 0.5% 0.2% 9.1% Maximum temperature resistance [°C] 185 175 195 125 Acid and alkali stability (pH 4-10) No abnormal milk breakdown No abnormal milk breakdown No abnormal milk breakdown Demulsification, layering The two comparison tables clearly show that the embodiments of the present invention are superior to the comparative examples in terms of basic performance, environmental friendliness, application adaptability, and durability. The embodiments have high thermal conductivity, no VOC emissions, uniform particle size distribution, and stable storage. They also demold smoothly without residue, can be reused many times, and are resistant to temperature, acid, and alkali. In contrast, the comparative examples, due to the use of a single filler, non-environmentally friendly additives, and simplified processes, suffer from poor thermal conductivity, excessive VOCs, insufficient stability, and poor demolding effect. This fully demonstrates the advanced nature and practicality of the technical solution of the present invention.

[0067] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high thermal conductivity, environmentally friendly modified polyurethane release agent, characterized in that, By weight percentage, it includes the following components: 38-42% epoxy-modified quaternary ammonium salt hydrochloric polyurethane emulsion, 8-12% ternary composite thermally conductive filler, 1.8-2.2% environmentally friendly silane coupling agent, 1.2-1.8% VOC-free polyurethane thickener, 0.3-0.5% plant-based defoamer, 0.5-1% environmentally friendly anti-migration agent, and deionized water to make up to 100%.

2. The high thermal conductivity environmentally friendly modified polyurethane release agent according to claim 1, characterized in that, The epoxy-modified quaternary ammonium salt hydrochloric polyurethane emulsion is prepared by stepwise polymerization of isophorone diisocyanate, polybutylene adipate diol, N-methyldiethanolamine, and epichlorohydrin. It has a solid content of 45-48%, an epoxy value of 0.05-0.08 eq / 100g, a number average molecular weight of 20,000-30,000, and a molecular weight distribution index of 1.2-1.

5.

3. The high thermal conductivity environmentally friendly modified polyurethane release agent according to claim 1, characterized in that, The ternary composite thermally conductive filler is composed of nanocrystalline aluminum nitride, silane-modified boron nitride / graphene composite, and nano-silicon carbide in a mass ratio of 1:2:0.

5. The nanocrystalline aluminum nitride has a particle size of 60-80 nm. The silane-modified boron nitride / graphene composite has a boron nitride to graphene mass ratio of 2:1 and is grafted with KH-570. The nano-silicon carbide has a particle size of 30-50 nm. The KH-570 grafting rate of the silane-modified boron nitride / graphene composite is 8-12%, and the specific surface area is ≥50 m². 2 / g.

4. The high thermal conductivity environmentally friendly modified polyurethane release agent according to claim 1, characterized in that, The environmentally friendly anti-migration agent is a polylactic acid-grafted polyethylene glycol copolymer with a number average molecular weight of 5000-8000, a glass transition temperature of 55-65℃, and a thermal decomposition temperature of ≥300℃.

5. The high thermal conductivity environmentally friendly modified polyurethane release agent according to claim 3, characterized in that, Nano-silicon carbide has a thermal conductivity of 120-150 W / (m·K) and a resistivity ≥10⁻⁶. 16 After surface modification with γ-aminopropyltriethoxysilane, the water contact angle is ≤30°, the oil absorption value is ≤20mL / 100g, and the dispersion stability is ≥96h.

6. The high thermal conductivity environmentally friendly modified polyurethane release agent according to claim 1, characterized in that, The VOC-free polyurethane thickener is a VOC-free nonionic associative polyurethane thickener; the plant-based defoamer is a polyether-modified tea saponin defoamer.

7. A method for preparing a high thermal conductivity, environmentally friendly modified polyurethane release agent as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Pretreatment of ternary composite thermally conductive filler: Nanocrystalline aluminum nitride, silane-modified boron nitride / graphene composite, and nano-silicon carbide are mixed in proportion and subjected to plasma treatment under an argon atmosphere for 10-15 min with a plasma power of 800-1000W. Then, deionized water is added to prepare a suspension with a mass fraction of 12-14%. The suspension is ultrasonically dispersed at a power of 350-450W for 25-35 min. An environmentally friendly silane coupling agent is added, and the mixture is stirred at 350-450r / min for 1.2-1.8 h at 62-68℃ to obtain a modified thermally conductive filler dispersion. S2. Preparation of epoxy-modified quaternary ammonium salt hydrochloric polyurethane emulsion: Polybutylene adipate diol was vacuum dehydrated at 100-110℃ for 2-3h, cooled to 60-65℃ and added isophorone diisocyanate, reacted at 75-80℃ for 2-2.5h, N-methyldiethanolamine was added and reacted for 1-1.5h, cooled to 40-45℃ and added epichlorohydrin, reacted at 50-55℃ for 1.5-2h, neutralized to pH 7.0-7.5 with triethanolamine and then emulsified with water to obtain the emulsion; S3. Composite modification: Add the emulsion obtained in step S2 to the reaction vessel, stir at 850-950 r / min for 35-40 min at 58-62℃, adjust the pH to 7.8-8.2, and dropwise add the dispersion from step S1 at a rate of 5-8 mL / min. After the addition is complete, raise the temperature to 70-80℃ and shear disperse at 1400-1600 r / min for 45-55 min. During this period, the particle size is detected by a laser particle size analyzer every 15 min to ensure that D90≤1.5μm. S4. Additives and Curing: Add VOC-free nonionic associative polyurethane thickener, polyether-modified tea saponin defoamer, and environmentally friendly anti-migration agent in sequence. Stir at 600-700 r / min for 18-22 min at 62-68℃, cool to 25-30℃, and cure for 20-22 h. During this period, stir at 250-300 r / min for 10 min every 6 h. Filter through 250-280 mesh filter cloth to obtain the release agent.

8. The preparation method of the high thermal conductivity environmentally friendly modified polyurethane release agent according to claim 7, characterized in that, In step S2, the molar ratio of isophorone diisocyanate to polybutylene adipate diol is 1.8:1-2.2:1, the amount of N-methyldiethanolamine added is 8-12% of the mass of polybutylene adipate diol, the amount of epichlorohydrin added is 5-8% of the total mass of the reaction system, the stirring speed during emulsification is 1200-1500 r / min, and the emulsification time is 20-30 min.

9. The preparation method of the high thermal conductivity environmentally friendly modified polyurethane release agent according to claim 7, characterized in that, In step S3, a gradient heating strategy is adopted during high-speed shear dispersion. The temperature is increased by 5°C every 10 minutes to the target temperature. During the droplet addition, the temperature fluctuation of the system is kept ≤±2°C by a constant temperature jacket. After the high-speed shear is completed, the system is kept at the temperature and stirred for 30 minutes at a stirring speed of 800 r / min.

10. The preparation method of the high thermal conductivity environmentally friendly modified polyurethane release agent according to claim 7, characterized in that, In step S4, the curing environment is a clean, dust-free space with humidity controlled at 40-60%. The filtered release agent must be tested by a laser particle size analyzer to ensure that the particle size distribution span is ≤1.2 and the thermal conductivity is tested by a thermal conductivity meter to ensure that the thermal conductivity is ≥1.5 W / (m·K). Only after passing the tests can it be packaged. The packaging container is a light-proof polyethylene drum, sealed and stored at a temperature of 5-35℃.

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