Preparation method of a water-based high-temperature release agent for hexagonal boron nitride

Abstract

The present invention relates to the field of high-temperature release agents, and discloses a preparation method of a water-based hexagonal boron nitride high-temperature release agent. The release agent comprises the following components in parts by weight: 25-40 parts of modified hexagonal boron nitride, 35-65 parts of softened water, 10-25 parts of binder, and 0.3-0.5 part of defoamer; the modified hexagonal boron nitride is prepared by carboxylating hydroxylated hexagonal boron nitride with γ-aminopropyltriethoxysilane and succinic anhydride, mixing it with a functionalized filler, and then carrying out a grafting reaction with amino-terminated sodium tripolyphosphate, wherein the functionalized filler is prepared by in-situ growing silica nanoparticles using graphitic carbon nitride as a carrier; the preparation method comprises the following steps: weighing each raw material according to parts by weight, ball-milling the modified hexagonal boron nitride, adding softened water and stirring for dispersion, after the dispersion is completed, grinding with a high-speed disperser to obtain a mixture, and then adding a binder and a defoamer to the mixture and continuing to stir to prepare the water-based hexagonal boron nitride high-temperature release agent.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-temperature mold release agents, and particularly relates to a preparation method of a water-based hexagonal boron nitride high-temperature mold release agent. Background Art

[0002] In the field of metal and non-metal forming and processing, the emergence of molds has accelerated the efficiency of material forming. However, the qualified rate of material forming mainly depends on the mold release agent. The mold release agent is a functional substance applied between the product and the mold, and its main function is to smoothly demold the product and ensure that the surface of the product is flat, smooth, and free of scratches and other marks. There are various types of mold release agents. Classified by solvent, they mainly include: water-based mold release agents, oil-based mold release agents, and powder mold release agents. In the field of high-temperature processing, the mold release agent needs to have the properties of not decomposing at high temperatures and high lubrication performance.

[0003] The prior art selects water-based hexagonal boron nitride as the mold release agent. The water-based hexagonal boron nitride mold release agent mainly relies on the poor wettability of molten metal to hexagonal boron nitride and the lamellar structure of hexagonal boron nitride. Hexagonal boron nitride has chemical inertness and a relatively high surface energy, and its dispersibility in the lubricating medium is poor and it is prone to agglomeration during the sliding process, reducing its lubrication performance. At the same time, due to the different electronegativities of boron atoms and nitrogen atoms, a strong polarity is generated between the lamellae of hexagonal boron nitride, which can inhibit the slip between layers, reducing the friction reduction and anti-wear performance of hexagonal boron nitride. In addition, due to the low viscosity of water, it is difficult to form an elastohydrodynamic lubricating film between the substrates, resulting in a large friction coefficient and affecting the flatness of the product. Summary of the Invention

[0004] To solve the deficiencies mentioned in the above background art, the purpose of the present invention is to provide a preparation method of a water-based hexagonal boron nitride high-temperature mold release agent. By adding modified hexagonal boron nitride, the mold release agent is given excellent lubricity and high-temperature adhesion, and the demolding effect is good.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A preparation method of a water-based hexagonal boron nitride high-temperature mold release agent, wherein the water-based hexagonal boron nitride high-temperature mold release agent comprises the following components in parts by weight: 25-40 parts of modified hexagonal boron nitride, 35-65 parts of softened water, 10-25 parts of binder, and 0.3-0.5 parts of defoamer;

[0007] The modified hexagonal boron nitride is prepared by carboxylating hydroxylated hexagonal boron nitride with γ-aminopropyltriethoxysilane and succinic anhydride, mixing it with a functionalized filler, and then carrying out a grafting reaction with aminotrimethyl phosphate, wherein the functionalized filler is prepared by in-situ growing silica nanoparticles using graphitic carbon nitride as a carrier;

[0008] The preparation method of the water-based hexagonal boron nitride high-temperature mold release agent comprises the following steps:

[0009] Weigh each raw material by weight. Ball-mill the modified hexagonal boron nitride in a ball mill tank to 3 - 5 μm, add softened water and stir for dispersion for 1.5 - 2 h. After the dispersion is completed, grind it with a high-speed disperser for 4 - 6 h to obtain a mixture with a fineness of 1 - 5 μm. Then, add a binder and an antifoaming agent to the mixture and continue stirring for 0.5 - 1 h to prepare the water-based hexagonal boron nitride high-temperature mold release agent.

[0010] Preferably, the binder is one or a combination of more of aluminum dihydrogen phosphate, aluminum sol, and aluminum sulfate.

[0011] Preferably, the antifoaming agent is an organosilicon antifoaming agent.

[0012] Preferably, the preparation method of the modified hexagonal boron nitride comprises the following steps:

[0013] (1) Take hexagonal boron nitride in a reactor, add sodium hydroxide solution and stir for 42 - 48 h, and then carry out centrifugation, washing, and drying to prepare hydroxylated hexagonal boron nitride;

[0014] (2) Take graphitic carbon nitride and ultrasonically disperse it in deionized water, then add anhydrous citric acid and continue ultrasonic treatment for 1.5 - 2 h to prepare protonated graphitic carbon nitride;

[0015] (3) Take sodium silicate in a reactor, add deionized water and mix, slowly add ethanol, then raise the temperature to 75 - 85 °C, add protonated graphitic carbon nitride, adjust the pH value of the system to 5 - 6 with concentrated sulfuric acid solution, then add ethanol, stop the reaction when the reaction temperature is maintained at 75 - 85 °C, age for 1 - 2 h, then centrifuge and discard the supernatant, and wash with deionized water and ethanol, and dry with a freeze dryer to prepare a functionalized filler;

[0016] (4) Take γ-aminopropyltriethoxysilane and succinic anhydride in N,N-dimethylformamide, place it at 75 - 90 °C and stir for 2 - 5 h to form a mixed solution. Take hydroxylated hexagonal boron nitride and the functionalized filler and ultrasonically disperse them in N,N-dimethylformamide, add deionized water and mix, then add it to the mixed solution and continue stirring for 4 - 6 h. After the reaction is completed, carry out centrifugation, washing, and drying to prepare a carboxylated composite material;

[0017] (5) Take sodium tripolyphosphate and γ-aminopropyltriethoxysilane and dissolve them in toluene solvent, place it at 65 - 75 °C and react for 5 - 6 h. After the reaction is completed, carry out centrifugation, washing, and drying to prepare amino-functionalized sodium tripolyphosphate;

[0018] (6) The carboxyl composite material is ultrasonically dispersed in deionized water to obtain a dispersion, and deionized water, 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide are mixed to obtain a mixed solution. The mixed solution is added to the dispersion and allowed to stand for 0.5 to 1 h. Aminated sodium tripolyphosphate is then added and stirred at 30 to 50 °C for 5 to 6 h. After the reaction is completed, the modified hexagonal boron nitride is prepared by centrifugation, washing and drying.

[0019] Preferably, in step (3), the mass ratio of sodium silicate to protonated graphite phase carbon nitride is 20:3-7.

[0020] Preferably, in step (4), the mass ratio of γ-aminopropyltriethoxysilane, succinic anhydride, hydroxylated hexagonal boron nitride and functionalized filler is 7-10:9-12:1-3:0.5-1.

[0021] Preferably, in step (5), the mass ratio of sodium tripolyphosphate to γ-aminopropyltriethoxysilane is 1:1.4-2.

[0022] Preferably, in step (6), the mass ratio of 1-ethyl-(3-dimethylaminopropyl)carbodiimide to N-hydroxysuccinimide is 7.5-8.5:1.

[0023] Beneficial effects of the present invention:

[0024] The present invention uses sodium hydroxide solution to perform hydroxylation on hexagonal boron nitride, and uses citric acid to protonate graphite phase carbon nitride to form a positive charge center, and then the precursor of silicon dioxide SiO 3 2- The silicon dioxide nanoparticles are adsorbed on the surface of graphite carbon nitride by electrostatic attraction, and then the silicon dioxide nanoparticles are in-situ grown on the surface of graphite carbon nitride to form a functionalized filler. The addition of the functionalized filler can give the release agent excellent high temperature resistance, chemical stability and lubricity, and has sufficient adsorption strength at high temperature, and can form a complete and uniform lubricating film during the deformation of the product. The present invention further uses γ-aminopropyltriethoxysilane and succinic anhydride to carboxylate the hydroxylated hexagonal boron nitride and the functionalized filler, and at the same time uses γ-aminopropyltriethoxysilane to amino-modify sodium tripolyphosphate and then performs an amidation reaction with the carboxylated composite material. The introduced sodium phosphate group has stronger water solubility. The sodium tripolyphosphate, hexagonal boron nitride and the functionalized filler are firmly bonded through chemical bonds, and can be dispersed more evenly in the matrix. The modified hexagonal boron nitride can reduce its surface polarity and inhibit its agglomeration in the matrix, thereby reducing its interlayer friction. DETAILED DESCRIPTION

[0025] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0026] Embodiment 1 A preparation method of modified hexagonal boron nitride includes the following steps:

[0027] (1) Take 2.5 g of hexagonal boron nitride in a reactor, add a sodium hydroxide solution with a mass concentration of 40%, stir for 48 h, and after centrifugation, washing, and drying, hydroxylated hexagonal boron nitride is prepared;

[0028] (2) Take 5 g of graphitic carbon nitride and ultrasonically disperse it in 100 mL of deionized water, then add 35.7 g of anhydrous citric acid and continue ultrasonic treatment for 2 h to prepare protonated graphitic carbon nitride;

[0029] (3) Take 40 g of sodium silicate in a reactor, add 120 mL of deionized water and mix, slowly add 10 mL of ethanol, then heat up to 80 °C, add 10.5 g of protonated graphitic carbon nitride, adjust the pH value of the system to 6 with a concentrated sulfuric acid solution, then add 80 mL of ethanol, stop the reaction when the reaction temperature is maintained at 80 °C, age for 2 h, then centrifuge to discard the supernatant, wash with deionized water and ethanol, and dry with a freeze dryer to prepare a functionalized filler;

[0030] (4) Take 7.3 g of γ-aminopropyltriethoxysilane and 9.5 g of succinic anhydride in 100 mL of N,N-dimethylformamide, place it at 85 °C and stir for 4 h to form a mixed solution. Take 2.6 g of hydroxylated hexagonal boron nitride and 0.7 g of functionalized filler, ultrasonically disperse them in 100 mL of N,N-dimethylformamide, add 10 mL of deionized water and mix, then add it to the mixed solution and continue stirring for 5 h. After the reaction is completed, centrifuge, wash, and dry to prepare a carboxylated composite material;

[0031] (5) Take 4 g of sodium tripolyphosphate and 6.4 g of γ-aminopropyltriethoxysilane and dissolve them in 50 mL of toluene solvent, place it at 70 °C and react for 6 h. After the reaction is completed, centrifuge, wash, and dry to prepare amino-functionalized sodium tripolyphosphate;

[0032] (6) Take 1.5 g of the carboxylated composite material and ultrasonically disperse it in 150 mL of deionized water to obtain a dispersion. Take 60 mL of deionized water, 4 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide, and 0.5 g of N-hydroxysuccinimide, mix them evenly to obtain a mixed solution. Add the mixed solution to the dispersion, let it stand for 0.5 h, then add 6.5 g of aminated sodium tripolyphosphate, place it at 45 °C and stir for 6 h. After the reaction is completed, centrifuge, wash, and dry to prepare the modified hexagonal boron nitride.

[0033] Example 2 A water-based high-temperature mold release agent for hexagonal boron nitride comprises the following components in parts by weight: 27 parts of the modified hexagonal boron nitride prepared in Example 1, 35 parts of softened water, 12 parts of binder aluminum dihydrogen phosphate, and 0.3 part of Defoamer 6800.

[0034] The preparation method of the above water-based high-temperature mold release agent for hexagonal boron nitride comprises the following steps:

[0035] Weigh each raw material according to the parts by weight. Ball-mill the modified hexagonal boron nitride in a ball mill tank to 3 - 5 μm, add softened water and stir for 2 h. After the dispersion is completed, grind it with a high-speed disperser for 5 h to obtain a mixture with a fineness of 1 - 5 μm. Then add the binder and defoamer to the mixture and continue to stir for 1 h to prepare the water-based high-temperature mold release agent for hexagonal boron nitride.

[0036] Example 3 A water-based high-temperature mold release agent for hexagonal boron nitride comprises the following components in parts by weight: 35 parts of the modified hexagonal boron nitride prepared in Example 1, 52 parts of softened water, 17 parts of binder aluminum dihydrogen phosphate, and 0.4 part of Defoamer 6800.

[0037] The preparation method of the above water-based high-temperature mold release agent for hexagonal boron nitride is the same as that of Example 2.

[0038] Example 4 A water-based high-temperature mold release agent for hexagonal boron nitride comprises the following components in parts by weight: 40 parts of the modified hexagonal boron nitride prepared in Example 1, 63 parts of softened water, 24 parts of binder aluminum dihydrogen phosphate, and 0.5 part of Defoamer 6800.

[0039] The preparation method of the above water-based high-temperature mold release agent for hexagonal boron nitride is the same as that of Example 2.

[0040] Comparative Example 1 A preparation method of modified hexagonal boron nitride comprises the following steps:

[0041] (1) Take 2.5 g of hexagonal boron nitride in a reactor, add a sodium hydroxide solution with a mass concentration of 40% and stir for 48 h. After centrifugation, washing, and drying, prepare hydroxylated hexagonal boron nitride;

[0042] (2) 7.3 g of γ-aminopropyltriethoxysilane and 9.5 g of succinic anhydride were dissolved in 100 mL of N, N-dimethylformamide and stirred at 85 °C for 4 h to form a mixed solution. 2.6 g of hydroxylated hexagonal boron nitride and 0.7 g of nano-silicon dioxide were ultrasonically dispersed in 100 mL of N, N-dimethylformamide, 10 mL of deionized water was added and mixed, and then added to the mixed solution and stirred for 5 h. After the reaction was completed, the mixture was centrifuged, washed and dried to prepare a carboxylated composite material.

[0043] (3) 4 g of sodium tripolyphosphate and 6.4 g of γ-aminopropyltriethoxysilane were dissolved in 50 mL of toluene solvent and reacted at 70° C. for 6 h. After the reaction was completed, the mixture was centrifuged, washed, and dried to prepare aminated sodium tripolyphosphate;

[0044] (4) 1.5 g of the carboxylated composite material was ultrasonically dispersed in 150 mL of deionized water to obtain a dispersion, 60 mL of deionized water, 4 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 0.5 g of N-hydroxysuccinimide were mixed evenly to obtain a mixed solution, the mixed solution was added to the dispersion, allowed to stand for 0.5 h, and then 6.5 g of amino sodium tripolyphosphate was added. The mixture was stirred and reacted at 45 °C for 6 h. After the reaction was completed, the mixture was centrifuged, washed and dried to obtain modified hexagonal boron nitride.

[0045] Comparative Example 2 A water-based hexagonal boron nitride high-temperature release agent comprises the following components in parts by weight: 40 parts of modified hexagonal boron nitride prepared in Comparative Example 1, 63 parts of softened water, 24 parts of binder aluminum dihydrogen phosphate, and 0.5 parts of Deqian defoamer 6800.

[0046] The preparation method of the above-mentioned water-based hexagonal boron nitride high-temperature release agent is the same as that of Example 2.

[0047] Comparative Example 3 A water-based hexagonal boron nitride high-temperature release agent comprises the following components in parts by weight: 30 parts of hexagonal boron nitride, 7 parts of nano-silicon dioxide, 3 parts of graphite phase carbon nitride, 2 parts of sodium tripolyphosphate, 63 parts of softened water, 24 parts of binder aluminum dihydrogen phosphate, and 0.5 parts of Deqian defoamer 6800.

[0048] The preparation method of the above-mentioned water-based hexagonal boron nitride high-temperature release agent is the same as that of Example 2.

[0049] Performance Testing

[0050] The release agents prepared in Examples 2-4 and Comparative Examples 2-3 were tested for performance:

[0051] (1) High-temperature adhesion performance test: Using Q-235 as a test piece, the release agents prepared in Examples 2-4 and Comparative Examples 2-3 were tested for adhesion performance at different temperatures. The data results are shown in Table 1.

[0052] (2)Lubricating performance detection: Using SUS-304 as a test piece, the mold release agents prepared in Examples 2-4 and Comparative Examples 2-3 were measured for friction coefficient, and the data results are shown in Table 1.

[0053] Table 1 Test results of sample performance.

[0054]

[0055] It can be seen from the data in Table 1 that the mold release agents prepared in Examples 2-4 of the present invention have sufficient adsorption strength at high temperature, low friction coefficient, and good lubricating and demolding properties. In Comparative Example 2, the functionalized filler was replaced with nano-silica in equal amount, and the measured adhesion amount at high temperature was significantly lower than that in Examples 2-4, and the friction coefficient was slightly lower than that in Examples 2-4, indicating that the addition of graphitic carbon nitride can improve the high-temperature adhesion and lubricity of the mold release agent. In Comparative Example 3, hexagonal boron nitride, nano-silica and graphitic carbon nitride were simply mixed, and the measured friction coefficient was higher than that in Examples 2-4, and the high-temperature adhesion amount was slightly lower than that in Examples 2-4. The reason is that its water solubility and dispersibility in the matrix are poor, resulting in a decrease in its performance.

[0056] In the description of this specification, the description with reference to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0057] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art of this industry should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A method for preparing a water-based hexagonal boron nitride high-temperature release agent, characterized in that: The water-based hexagonal boron nitride high-temperature release agent comprises the following components in parts by weight: 25-40 parts of modified hexagonal boron nitride, 35-65 parts of softened water, 10-25 parts of a binder, and 0.3-0.5 parts of a defoamer; The preparation method of the modified hexagonal boron nitride comprises the following steps: (1) Put hexagonal boron nitride in a reactor, add sodium hydroxide solution and stir for 42-48 hours, centrifuge, wash and dry to prepare hydroxylated hexagonal boron nitride; (2) ultrasonically dispersing graphite phase carbon nitride in deionized water, then adding anhydrous citric acid and continuing ultrasonication for 1.5 to 2 hours to prepare protonated graphite phase carbon nitride; (3) Sodium silicate was placed in a reactor, deionized water was added and mixed, ethanol was slowly added and the temperature was raised to 75-85°C, protonated graphite carbon nitride was added, the pH value of the system was adjusted to 5-6 with concentrated sulfuric acid solution, and ethanol was added. The reaction was stopped when the reaction temperature was maintained at 75-85°C, and the supernatant was discarded after aging for 1-2 hours, and the mixture was washed with deionized water and ethanol, and dried in a freeze dryer to prepare a functionalized filler; (4) γ-aminopropyltriethoxysilane and succinic anhydride are placed in N,N-dimethylformamide and stirred at 75-90°C for 2-5 hours to form a mixed solution, hydroxylated hexagonal boron nitride and functionalized filler are ultrasonically dispersed in N,N-dimethylformamide, deionized water is added and mixed, and then added to the mixed solution and stirred for 4-6 hours. After the reaction is completed, the mixture is centrifuged, washed, and dried to prepare a carboxylated composite material; (5) dissolving sodium tripolyphosphate and γ-aminopropyltriethoxysilane in toluene solvent, reacting at 65-75° C. for 5-6 hours, and after the reaction is completed, centrifuging, washing, and drying to prepare aminated sodium tripolyphosphate; (6) Ultrasonic dispersion of the carboxylated composite material in deionized water to obtain a dispersion, deionized water, 1-ethyl-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide were mixed to obtain a mixed solution, the mixed solution was added to the dispersion, and the mixture was allowed to stand for 0.5 to 1 hour, and then the aminated sodium tripolyphosphate was added, and the mixture was stirred at 30 to 50° C. for 5 to 6 hours. After the reaction was completed, the mixture was centrifuged, washed, and dried to obtain modified hexagonal boron nitride; In step (3), the mass ratio of sodium silicate to protonated graphite phase carbon nitride is 20:3-7; In the step (4), the mass ratio of γ-aminopropyltriethoxysilane, succinic anhydride, hydroxylated hexagonal boron nitride and functionalized filler is 7-10:9-12:1-3:0.5-1; In the step (5), the mass ratio of sodium tripolyphosphate to γ-aminopropyltriethoxysilane is 1:1.4-2; In step (6), the mass ratio of 1-ethyl-(3-dimethylaminopropyl)carbodiimide to N-hydroxysuccinimide is 7.5-8.5:1; The preparation method of the water-based hexagonal boron nitride high-temperature release agent comprises the following steps: Weigh each raw material by weight, ball-mill the modified hexagonal boron nitride to 3-5 μm in a ball mill, add softened water and stir and disperse for 1.5-2 h. After dispersion, grind it in a high-speed disperser for 4-6 h to obtain a mixture with a fineness of 1-5 μm, then add a binder and a defoamer to the mixture and continue stirring for 0.5-1 h to prepare a water-based hexagonal boron nitride high-temperature release agent.

2. The method for preparing the water-based hexagonal boron nitride high-temperature release agent according to claim 1, characterized in that: The binder is one or more combinations of aluminum dihydrogen phosphate, aluminum sol, and aluminum sulfate.

3. The method for preparing the water-based hexagonal boron nitride high-temperature release agent according to claim 1, characterized in that: The defoamer is an organosilicon defoamer.

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