Cold core box binder and preparation method thereof

Abstract

The invention provides a cold core box binder and a preparation method thereof, the binder is a two-component binder system, a component I comprises alumina sol particle modified phenolic resin and an aromatic solvent, and a component II comprises polyisocyanate and an aromatic solvent; wherein the aluminum sol particle modified phenolic resin is obtained by adding composite aluminum sol particles into a reaction system of phenol and formaldehyde and carrying out catalytic reaction through a base catalyst. The invention provides a cold core box binder which is combined with a nanoparticle modification technology to develop a high-performance cold core box binder suitable for a high-temperature casting environment.

Description

Technical Field

[0001] The present invention relates to the technical field of casting binders, and particularly relates to a cold box binder and a preparation method thereof. Background Art

[0002] Phenolic resin is one of the commonly used binders in the cold box core-making process, and is usually used in combination with polyisocyanate (PAPI). With triethylamine as a catalyst, it rapidly hardens under the action of a gas generator to form a sand core with a certain strength. This method does not require heating and has the advantages of rapid reaction, short curing cycle, high sand core accuracy, and low cost. Cold box binders are key materials in the casting process, mainly used for the forming and curing of sand cores. Due to its rapid curing, high bonding strength, and environmental friendliness, phenolic resin has become an important component of cold box binders. However, with the increasing requirements for the performance of sand cores in the casting industry, the limitations of traditional phenolic resins in terms of high temperature resistance and mechanical strength have gradually emerged. For example, in a high-temperature casting environment, the resin is prone to thermal decomposition, resulting in a decrease in the strength of the sand core; at the same time, the brittleness of the resin also limits its application in sand cores with complex structures. In recent years, its performance under high-temperature conditions has been further improved through modification technologies (such as adding plasticizers and epoxy groups). The nano-particle modification technology provides new ideas for improving the performance of cold box binders. The introduction of nano-particles can not only improve the mechanical properties of the resin but also enhance its heat resistance. For example, the thermal decomposition temperature of a phenolic resin composite containing nano-SiO2 is significantly increased at high temperatures, and its thermal decay resistance is enhanced; the addition of rare earth elements (such as CeO2, Y2O3) further improves the heat resistance and toughness of the resin. The rare earth ions have a blocking effect on the phenolic hydroxyl groups in the resin, reducing the possibility of thermal degradation; in addition, the introduction of nano-Al2O3 and nano-TiO2 can significantly improve the high-temperature resistance and mechanical strength of the resin; while the addition of graphene can enhance the toughness and thermal conductivity of the resin. In addition, nano-particles can also improve the curing performance of the resin, enabling it to cure rapidly at room temperature, thereby reducing energy consumption and production costs. Summary of the Invention

[0003] Technical problems to be solved: The purpose of the present invention is to provide a cold box binder, combining nano-particle modification technology, to develop a high-performance cold box binder suitable for high-temperature casting environments.

[0004] Technical solution: A cold box binder, the binder is a two-component binder system, component I includes phenolic resin modified with aluminum sol particles and aromatic hydrocarbon solvent, and component II includes polyisocyanate and aromatic hydrocarbon solvent; Among them, the phenolic resin modified with aluminum sol particles is obtained by adding composite aluminum sol particles to the reaction system of phenol and formaldehyde and catalyzing the reaction with an alkali catalyst. Preferably, the mass ratio of Component I to Component II is 10:5 to 30; and / or, the mass ratio of the aluminosilicate particle-modified phenolic resin to the aromatic hydrocarbon solvent is 10:1 to 4; and / or, the mass ratio of the polyisocyanate to the aromatic hydrocarbon solvent is 10:1 to 3. Preferably, the polyisocyanate is any one or more of toluene diisocyanate, diphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, or hexamethylene diisocyanate; and / or, the aromatic hydrocarbon solvent is any one or more of aromatic hydrocarbon S-100, aromatic hydrocarbon S-150, aromatic hydrocarbon S-180, or aromatic hydrocarbon S-200. Preferably, the method for preparing the aluminosilicate particle-modified phenolic resin comprises the following steps: S1. Mix and stir phenol, aqueous formaldehyde solution, and an alkali catalyst until dissolved uniformly to obtain a mixed solution system; S2. Heat the mixed solution system to 60 - 65°C, add aluminosilicate particles, stir uniformly and keep warm for 1 - 2 h, then heat to 80 - 85°C, keep warm for 1 - 2 h to obtain a brownish liquid, and perform vacuum distillation to obtain the aluminosilicate particle-modified phenolic resin. Preferably, the alkali catalyst is any one or more of Ca(OH)2, LiOH·H2O, NaOH, or KOH; and / or, the molar ratio of phenol, formaldehyde, and the alkali catalyst is 1:2 - 2.8:0.04 - 0.06, and the concentration of the aqueous formaldehyde solution is 37 wt%; and / or, the mass ratio of the mixed solution system to the aluminosilicate particles is 100:3 to 6. Preferably, the method for preparing the aluminosilicate particles comprises the following steps: S11. Dissolve aluminum chloride hexahydrate in water, stir until completely dissolved, then add aluminum powder, and heat under reflux at 80 - 90°C for 3 - 5 h to obtain an aluminosilicate sol; S12. Add PVP to ethanol with a concentration of 0.5 - 1 wt% CaCl2, stir to dissolve to obtain a PVP solution with a concentration of 5 - 10 wt%, then add microcapsules of a silane coupling agent, stir the reaction evenly, and then add it to the aluminosilicate sol, and stir and mix evenly to obtain a mixed aluminosilicate sol; S13. High-speed stir and disperse the mixed aluminosilicate sol into vegetable oil containing Tween 80 to form a sol microemulsion, filter and dry to obtain aluminosilicate particles. Preferably, the molar ratio of aluminum chloride hexahydrate to aluminum powder is 1:2 - 4.5; And / or, the volume ratio of the silane coupling agent microcapsules, PVP solution and aluminum sol is 3-5:30:50-60; And / or, the rotation speed of the high-speed stirring is 2000-5000 r / min. Preferably, the preparation method of the silane coupling agent microcapsules is as follows: S21. Dissolve sodium alginate and starch in water to obtain a sodium alginate-starch dispersion; S22. Add the core material silane coupling agent to the sodium alginate-starch dispersion, and disperse the mixture at a high speed at a rotation speed of 4000-6000 r / min to form an oil-in-water emulsion. Finally, spray-dry the emulsion to obtain silane coupling agent microcapsules. Preferably, the concentration of sodium alginate in the dispersion is 1-2 wt%; And / or, the concentration of starch in the dispersion is 1.5-2.5 wt%; And / or, the silane coupling agent is any one or more of silane coupling agent KH-550, silane coupling agent KH-560, silane coupling agent KH-570 or silane coupling agent A-187. Beneficial effects: The cold box binder of the present invention has the following advantages: 1. In the present invention, aluminum sol particles are used to improve phenolic resin. Aluminum sol is generated by aluminum chloride hexahydrate and aluminum in water. Aluminum sol particles are prepared by compounding aluminum sol and PVP. The aluminum sol particles contain AlO(OH)·nH2O (Al-O-OH·nH2O), which will react with the groups in the phenolic resin molecule, and the combination of nanoparticles and phenolic resin is realized in the form of chemical bonds, which will be beneficial to improving the thermal stability of phenolic resin; 2. In the present invention, aluminum sol particles are prepared by compounding PVP and aluminum sol. Under high temperature conditions, PVP will decompose, and aluminum sol will form a network structure in the sand core; at the same time, under high temperature conditions, AlO(OH)·nH2O will dehydrate to generate γ-Al2O3 at 300-400 °C, improving the high temperature stability of the sand core; 3. In the present invention, the silane coupling agent is added in the form of microcapsules. At room temperature, the silane coupling agent microcapsules do not play a role. Under high temperature conditions, the cortex of the microcapsules ruptures, and the silane coupling agent in the microcapsules flows out; the main component of the sand core is silica. The silane coupling agent condenses with the hydroxyl groups in AlO(OH)·nH2O to form Si-O-Al bonds, enhancing the interfacial bonding force. The silane coupling agent acts as a "bridge" to connect AlO(OH) and SiO2 to form a Si-O-Al-O-Si network, thereby improving the high temperature resistance of the sand core. Specific embodiments The present invention will be further described below in conjunction with embodiments. The following embodiments are explanations of the present invention, and the present invention is not limited to the following embodiments: Example 1 The preparation method of aluminosilicate sol particle modified phenolic resin comprises the following steps: S1. Mix phenol, 37 wt% aqueous formaldehyde solution, and the molar ratio of phenol, formaldehyde and NaOH is 1:2:0.04, and stir and dissolve evenly to obtain a mixed solution system; S2. Heat the mixed solution system to 60 °C, add aluminosilicate sol particles, and the mass ratio of the mixed solution system to aluminosilicate sol particles is 100:6. Stir evenly and keep warm for 2 h, then heat to 80 °C and keep warm for 1 h to obtain a brown liquid. Carry out vacuum distillation to obtain aluminosilicate sol particle modified phenolic resin; Among them, the preparation method of aluminosilicate sol particles comprises the following steps: S11. Dissolve aluminum chloride hexahydrate in water, stir until completely dissolved, then add aluminum powder, and the molar ratio of aluminum chloride hexahydrate to aluminum powder is 1:2. Heat and reflux at 90 °C for 3 h to obtain aluminosilicate sol; S12. Add PVP K30 to ethanol with a concentration of 0.5 wt% CaCl2, stir and dissolve to obtain a 10 wt% PVP solution, then add silane coupling agent microcapsules, stir and react evenly, and then add to aluminosilicate sol. The volume ratio of silane coupling agent microcapsules, PVP solution and aluminosilicate sol is 3:30:50, and stir and mix evenly to obtain a mixed aluminosilicate sol; S13. Disperse the mixed aluminosilicate sol into vegetable oil containing Tween 80 at a rotation speed of 2000 r / min to form a sol microemulsion, filter and dry to obtain aluminosilicate sol particles; Among them, the preparation method of silane coupling agent microcapsules is: S21. Dissolve sodium alginate and starch in water to obtain a sodium alginate-starch dispersion, wherein the concentration of sodium alginate in the dispersion is 2 wt%, and the concentration of starch in the dispersion is 1.5 wt%; S22. Add the core material silane coupling agent KH-550 to the sodium alginate-starch dispersion, disperse the mixture at a high speed of 6000 r / min to form an oil-in-water emulsion, and finally spray-dry the emulsion to obtain silane coupling agent microcapsules. Example 2 The preparation method of aluminosilicate sol particle modified phenolic resin comprises the following steps: S1. Mix phenol, 37 wt% aqueous formaldehyde solution, and the molar ratio of phenol, formaldehyde and NaOH is 1:2.8:0.06, and stir and dissolve evenly to obtain a mixed solution system; S2. Heat the mixed solution system to 65 °C, add aluminum sol particles, and the mass ratio of the mixed solution system to the aluminum sol particles is 100:3. After stirring evenly and keeping warm for 1 h, heat it to 85 °C and keep warm for 1 h to obtain a brownish liquid. Then perform vacuum distillation to obtain aluminum sol particle-modified phenolic resin; Among them, the preparation method of the aluminum sol particles includes the following steps: S11. Dissolve aluminum chloride hexahydrate in water, stir until completely dissolved, and then add aluminum powder. The molar ratio of aluminum chloride hexahydrate to aluminum powder is 1:4.5. Heat and reflux at 80 °C for 5 h to obtain aluminum sol; S12. Add PVP K30 to ethanol with a concentration of 1 wt% CaCl2, stir to dissolve to obtain a 5 wt% PVP solution, then add silane coupling agent microcapsules, stir and react evenly, and then add it to the aluminum sol. The volume ratio of the silane coupling agent microcapsules, PVP solution and aluminum sol is 5:30:60. Stir and mix evenly to obtain a mixed aluminum sol; S13. Disperse the mixed aluminum sol in vegetable oil containing Tween 80 at a rotation speed of 5000 r / min to form a sol microemulsion, filter and dry to obtain aluminum sol particles; Among them, the preparation method of the silane coupling agent microcapsules is as follows: S21. Dissolve sodium alginate and starch in water to obtain a sodium alginate-starch dispersion. Among them, the concentration of sodium alginate in the dispersion is 1 wt%, and the concentration of starch in the dispersion is 2.5 wt%; S22. Add the core material silane coupling agent KH-550 to the sodium alginate-starch dispersion, disperse the mixed solution at a high speed of 4000 r / min to form an oil-in-water emulsion, and finally spray-dry the emulsion to obtain silane coupling agent microcapsules. Example 3 The preparation method of the aluminum sol particle-modified phenolic resin includes the following steps: S1. Mix phenol, 37 wt% aqueous formaldehyde solution, and the molar ratio of phenol, formaldehyde and NaOH is 1:2.2:0.05, and mix and stir until dissolved evenly to obtain a mixed solution system; S2. Heat the mixed solution system to 60 °C, add aluminum sol particles, and the mass ratio of the mixed solution system to the aluminum sol particles is 100:4. After stirring evenly and keeping warm for 1.5 h, heat it to 80 °C and keep warm for 1.5 h to obtain a brownish liquid. Then perform vacuum distillation to obtain aluminum sol particle-modified phenolic resin; Among them, the preparation method of the aluminum sol particles includes the following steps: S11. Dissolve aluminum chloride hexahydrate in water, stir until completely dissolved, and then add aluminum powder. The molar ratio of aluminum chloride hexahydrate to aluminum powder is 1:3. Heat and reflux at 85 °C for 3 h to obtain aluminum sol; S12. Add PVP K30 to ethanol with a concentration of 0.6 wt% CaCl₂, stir to dissolve, obtain a PVP solution with a concentration of 6 wt%, then add the silane coupling agent microcapsules, stir to react evenly, and then add it to the aluminum sol. The volume ratio of the silane coupling agent microcapsules, PVP solution and aluminum sol is 4:30:55, and stir and mix evenly to obtain a mixed aluminum sol; S13. Disperse the mixed aluminum sol into vegetable oil containing Tween 80 at a rotation speed of 3000 r / min to form a sol microemulsion, filter and dry to obtain aluminum sol particles; Among them, the preparation method of the silane coupling agent microcapsules is as follows: S21. Dissolve sodium alginate and starch in water to obtain a sodium alginate-starch dispersion. Among them, the concentration of sodium alginate in the dispersion is 1.4 wt%, and the concentration of starch in the dispersion is 1.8 wt%; S22. Add the core material silane coupling agent KH-550 to the sodium alginate-starch dispersion, disperse the mixture at a high speed of 4500 r / min to form an oil-in-water emulsion, and finally spray-dry the emulsion to obtain the silane coupling agent microcapsules. Example 4 The preparation method of the aluminum sol particle-modified phenolic resin includes the following steps: S1. Mix phenol, 37 wt% aqueous formaldehyde solution, and the molar ratio of phenol, formaldehyde and NaOH is 1:2.5:0.05, stir and dissolve evenly to obtain a mixed solution system; S2. Heat the mixed solution system to 60 °C, add aluminum sol particles, the mass ratio of the mixed solution system to the aluminum sol particles is 100:5, stir evenly and keep warm for 1.5 h, then heat to 80 °C and keep warm for 2 h to obtain a brown liquid, and carry out vacuum distillation to obtain the aluminum sol particle-modified phenolic resin; Among them, the preparation method of the aluminum sol particles includes the following steps: S11. Dissolve aluminum chloride hexahydrate in water, stir until completely dissolved, then add aluminum powder, the molar ratio of aluminum chloride hexahydrate to aluminum powder is 1:3, heat and reflux at 85 °C for 4 h to obtain aluminum sol; S12. Add PVP K30 to ethanol with a concentration of 0.8 wt% CaCl₂, stir to dissolve, obtain a PVP solution with a concentration of 8 wt%, then add the silane coupling agent microcapsules, stir to react evenly, and then add it to the aluminum sol. The volume ratio of the silane coupling agent microcapsules, PVP solution and aluminum sol is 5:30:55, and stir and mix evenly to obtain a mixed aluminum sol; S13. Disperse the mixed aluminum sol into vegetable oil containing Tween 80 at a rotation speed of 4000 r / min to form a sol microemulsion, filter and dry to obtain aluminum sol particles; Among them, the preparation method of the silane coupling agent microcapsules is as follows: S21. Dissolve sodium alginate and starch in water to obtain a sodium alginate-starch dispersion liquid, wherein the concentration of sodium alginate in the dispersion liquid is 1.5 wt%, and the concentration of starch in the dispersion liquid is 2.2 wt%; S22. Add the core material silane coupling agent KH-550 to the sodium alginate-starch dispersion liquid, and disperse the mixture at a high speed of 5500 r / min to form an oil-in-water emulsion. Finally, spray-dry the emulsion to obtain the silane coupling agent microcapsules. Example 5 A cold box binder, the binder is a two-component binder system. Component I includes the aluminum sol particle-modified phenolic resin prepared in Example 1 and aromatic hydrocarbon S-150, and Component II includes 1,6-hexamethylene diisocyanate and aromatic hydrocarbon S-150; Among them, the mass ratio of Component I to Component II is 10:12; the mass ratio of the aluminum sol particle-modified phenolic resin to aromatic hydrocarbon S-150 is 10:3; the mass ratio of 1,6-hexamethylene diisocyanate to aromatic hydrocarbon S-150 is 10:1. Example 6 A cold box binder, the binder is a two-component binder system. Component I includes the aluminum sol particle-modified phenolic resin prepared in Example 2 and aromatic hydrocarbon S-150, and Component II includes 1,6-hexamethylene diisocyanate and aromatic hydrocarbon S-150; Among them, the mass ratio of Component I to Component II is 10:15; the mass ratio of the aluminum sol particle-modified phenolic resin to aromatic hydrocarbon S-150 is 10:2; the mass ratio of 1,6-hexamethylene diisocyanate to aromatic hydrocarbon S-150 is 10:2. Example 7 A cold box binder, the binder is a two-component binder system. Component I includes the aluminum sol particle-modified phenolic resin prepared in Example 3 and aromatic hydrocarbon S-150, and Component II includes 1,6-hexamethylene diisocyanate and aromatic hydrocarbon S-150; Among them, the mass ratio of Component I to Component II is 10:8; the mass ratio of the aluminum sol particle-modified phenolic resin to aromatic hydrocarbon S-150 is 10:2; the mass ratio of 1,6-hexamethylene diisocyanate to aromatic hydrocarbon S-150 is 10:2. Example 8 A cold box binder, the binder is a two-component binder system. Component I includes the aluminum sol particle-modified phenolic resin prepared in Example 4 and aromatic hydrocarbon S-150, and Component II includes 1,6-hexamethylene diisocyanate and aromatic hydrocarbon S-150; Among them, the mass ratio of Component I to Component II is 10:9; the mass ratio of the aluminum sol particle modified phenolic resin to aromatic hydrocarbon S-150 is 10:3; the mass ratio of 1,6-hexamethylene diisocyanate to aromatic hydrocarbon S-150 is 10:2. Comparative Example 1 A cold box binder, the binder is a two-component binder system, Component I includes phenolic resin and aromatic hydrocarbon S-150, and Component II includes 1,6-hexamethylene diisocyanate and aromatic hydrocarbon S-150; Among them, the mass ratio of Component I to Component II is 10:9; the mass ratio of the phenolic resin to aromatic hydrocarbon S-150 is 10:3; the mass ratio of 1,6-hexamethylene diisocyanate to aromatic hydrocarbon S-150 is 10:2. Comparative Example 2 A cold box binder, the binder is a two-component binder system, Component I includes alumina modified phenolic resin and aromatic hydrocarbon S-150, and Component II includes 1,6-hexamethylene diisocyanate and aromatic hydrocarbon S-150; Among them, the mass ratio of Component I to Component II is 10:9; the mass ratio of the alumina modified phenolic resin to aromatic hydrocarbon S-150 is 10:3; the mass ratio of 1,6-hexamethylene diisocyanate to aromatic hydrocarbon S-150 is 10:2; The preparation method of the alumina modified phenolic resin includes the following steps: S1. Mix phenol, 37 wt% formaldehyde aqueous solution, and the molar ratio of phenol, formaldehyde and NaOH is 1:2.5:0.05, and stir and dissolve evenly to obtain a mixed solution system; S2. Heat the mixed solution system to 60°C, add micro-nano alumina, and the mass ratio of the mixed solution system to micro-nano alumina is 100:5. Stir evenly and keep warm for 1.5 h, then heat to 80°C and keep warm for 2 h to obtain a brown liquid, and perform vacuum distillation to obtain micro-nano alumina modified phenolic resin. Comparative Example 3 A cold box binder, the binder is a two-component binder system, Component I includes aluminum sol particle modified phenolic resin and aromatic hydrocarbon S-150, and Component II includes 1,6-hexamethylene diisocyanate and aromatic hydrocarbon S-150; Among them, the mass ratio of Component I to Component II is 10:9; the mass ratio of the aluminum sol particle modified phenolic resin to aromatic hydrocarbon S-150 is 10:3; the mass ratio of 1,6-hexamethylene diisocyanate to aromatic hydrocarbon S-150 is 10:2; The preparation method of the aluminum sol particle modified phenolic resin includes the following steps: S1. Mix phenol, 37 wt% aqueous formaldehyde solution, and with a molar ratio of phenol, formaldehyde, and NaOH of 1:2.5:0.05, and stir to dissolve evenly to obtain a mixed solution system; S2. Heat the mixed solution system to 60 °C, add aluminum sol particles with a mass ratio of the mixed solution system to aluminum sol particles of 100:5, stir evenly and keep warm for 1.5 h, then heat to 80 °C and keep warm for 2 h to obtain a brown liquid, and perform vacuum distillation to obtain aluminum sol particle modified phenolic resin; Among them, the preparation method of aluminum sol particles includes the following steps: S11. Dissolve aluminum chloride hexahydrate in water, stir until completely dissolved, then add aluminum powder with a molar ratio of aluminum chloride hexahydrate to aluminum powder of 1:3, heat and reflux at 85 °C for 4 h to obtain aluminum sol; S12. Add PVP K30 to ethanol with a concentration of 0.8 wt% CaCl2, stir to dissolve to obtain an 8 wt% PVP solution, add the PVP solution to the aluminum sol with a volume ratio of the PVP solution to the aluminum sol of 30:55, and stir and mix evenly to obtain a mixed aluminum sol; S13. Disperse the mixed aluminum sol into vegetable oil containing Tween 80 at a rotation speed of 4000 r / min to form a sol microemulsion, filter and dry to obtain aluminum sol particles. Comparative Example 4 A cold box binder, the binder is a two-component binder system, Component I includes aluminum sol particle modified phenolic resin, silane coupling agent KH-550 and aromatic hydrocarbon S-150, and Component II includes 1,6-hexamethylene diisocyanate and aromatic hydrocarbon S-150; Among them, the mass ratio of Component I to Component II is 10:9; the mass ratio of the aluminum sol particle modified phenolic resin, silane coupling agent KH-550 and aromatic hydrocarbon S-150 is 10:0.05:3; the mass ratio of 1,6-hexamethylene diisocyanate to aromatic hydrocarbon S-150 is 10:2; The preparation method of aluminum sol particle modified phenolic resin includes the following steps: S1. Mix phenol, 37 wt% aqueous formaldehyde solution, and with a molar ratio of phenol, formaldehyde, and NaOH of 1:2.5:0.05, and stir to dissolve evenly to obtain a mixed solution system; S2. Heat the mixed solution system to 60 °C, add aluminum sol particles with a mass ratio of the mixed solution system to aluminum sol particles of 100:5, stir evenly and keep warm for 1.5 h, then heat to 80 °C and keep warm for 2 h to obtain a brown liquid, and perform vacuum distillation to obtain aluminum sol particle modified phenolic resin; Among them, the preparation method of aluminum sol particles includes the following steps: S11. Dissolve aluminum chloride hexahydrate in water, stir until completely dissolved, then add aluminum powder. The molar ratio of aluminum chloride hexahydrate to aluminum powder is 1:3. Heat under reflux at 85 °C for 4 h to obtain an aluminum sol. S12. Add PVP K30 to ethanol with a concentration of 0.8 wt% CaCl2, stir to dissolve to obtain a PVP solution with a concentration of 8 wt%. Add the PVP solution to the aluminum sol. The volume ratio of the PVP solution to the aluminum sol is 30:55. Stir and mix evenly to obtain a mixed aluminum sol. S13. Disperse the mixed aluminum sol into vegetable oil containing Tween 80 at a rotation speed of 4000 r / min to form a sol microemulsion. Filter and dry to obtain aluminum sol particles. Comparative Example 5 A cold box binder, the binder is a two-component binder system. Component I includes the aluminum sol particle-modified phenolic resin prepared in Example 4 and aromatic hydrocarbon S-150. Component II includes 1,6-hexamethylene diisocyanate and aromatic hydrocarbon S-150; Among them, the mass ratio of Component I to Component II is 10:9; the mass ratio of the aluminum sol particle-modified phenolic resin to aromatic hydrocarbon S-150 is 10:3; the mass ratio of 1,6-hexamethylene diisocyanate to aromatic hydrocarbon S-150 is 10:2; The preparation method of the aluminum sol particle-modified phenolic resin includes the following steps: S1. Mix phenol, 37 wt% aqueous formaldehyde solution, and the molar ratio of phenol, formaldehyde, and NaOH is 1:2.5:0.05. Stir and dissolve evenly to obtain a mixed solution system; S2. Heat the mixed solution system to 60 °C, add aluminum sol particles. The mass ratio of the mixed solution system to the aluminum sol particles is 100:5. Stir evenly and keep warm for 1.5 h, then heat to 80 °C and keep warm for 2 h to obtain a brown liquid. Carry out vacuum distillation to obtain the aluminum sol particle-modified phenolic resin; Among them, the preparation method of the aluminum sol particles includes the following steps: S11. Dissolve aluminum chloride hexahydrate in water, stir until completely dissolved, then add aluminum powder. The molar ratio of aluminum chloride hexahydrate to aluminum powder is 1:3. Heat under reflux at 85 °C for 4 h to obtain an aluminum sol. S12. Add silane coupling agent microcapsules to the aluminum sol. The volume ratio of the silane coupling agent microcapsules to the aluminum sol is 5:80. Stir and mix evenly to obtain a mixed aluminum sol; S13. Disperse the mixed aluminum sol into vegetable oil containing Tween 80 at a rotation speed of 4000 r / min to form a sol microemulsion. Filter and dry to obtain aluminum sol particles; Among them, the preparation method of the silane coupling agent microcapsules is: S21. Dissolve sodium alginate and starch in water to obtain a sodium alginate - starch dispersion. Among them, the concentration of sodium alginate in the dispersion is 1.5 wt%, and the concentration of starch in the dispersion is 2.2 wt%. S22. Add the core material silane coupling agent KH - 550 to the sodium alginate - starch dispersion, and disperse the mixture at a high speed of 5500 r / min to form an oil - in - water emulsion. Finally, spray - dry the emulsion to obtain microcapsules. S23. Place the microcapsules in an ethanol solution containing aluminum ions and react to obtain silane coupling agent microcapsules. Performance test: First, weigh a certain amount of standard sand, add it to a muller, start the muller to stir, then add the binder in proportion, mix for 2 min, inject it into a metal core box through a core shooter, and pass in triethylamine for hardening to complete the preparation. First, add sand and Component I and mix for 90 seconds; then add Component II and mix for 90 seconds. Then, make the resin sand mixture into cylindrical specimens with a diameter of 12 mm and a height of 20 mm through an MLA1 - 2 core - making machine. The specimen size refers to JB / T 13037 - 2017 "Test Method for High - Temperature Properties of Coated Sand", and detect the tensile strength at 30 seconds and 24 hours respectively. After standing for 24 hours, refer to JB / T 13037 - 2017 "Test Method for High - Temperature Properties of Coated Sand" to detect the high - temperature heat - resistant time and high - temperature expansion rate at 1000℃. Detect the samples prepared in the examples and comparative examples respectively according to the above detection methods. The tensile strength and high - temperature performance results obtained are shown in Table 1 and Table 2. Table 1 shows the tensile strength of the samples at 30 seconds and 24 hours Table 2 shows the high - temperature heat - resistant time and high - temperature expansion rate of the samples at 1000℃ High-temperature heat resistance time at 1000℃ / s High-temperature expansion rate at 1000℃ / % Example 5 51 0.95 Example 6 55 0.92 Example 7 53 0.98 Example 8 52 0.93 Comparative Example 1 26 1.12 Comparative Example 2 30 0.89 Comparative Example 3 32 0.98 Comparative Example 4 28 1.02 Comparative Example 5 35 0.88 It can be seen from Table 1 and Table 2 that the initial strength and the final strength after 24 hours in the examples and comparative examples are not very different. However, under the high - temperature condition of 1000℃, the high - temperature resistance performance of the samples in the examples is significantly better than that of the samples in the comparative examples. Obviously, the above - mentioned examples are only illustrations clearly made, and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or alterations can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or alterations derived therefrom still fall within the protection scope of this invention.

Claims

1. A cold box binder, characterized in that: The binder is a two-component binder system. Component I includes aluminosilicate particle-modified phenolic resin and aromatic hydrocarbon solvent, and Component II includes polyisocyanate and aromatic hydrocarbon solvent; Among them, the aluminosilicate particle-modified phenolic resin is obtained by adding composite aluminosilicate particles to the reaction system of phenol and formaldehyde and catalyzing the reaction with an alkali catalyst.

2. The cold box binder according to claim 1, characterized in that: The mass ratio of Component I to Component II is 10:5 to 30; And / or, the mass ratio of the aluminosilicate particle-modified phenolic resin to the aromatic hydrocarbon solvent is 10:1 to 4; And / or, the mass ratio of the polyisocyanate to the aromatic hydrocarbon solvent is 10:1 to 3.

3. The cold box binder according to claim 1, characterized in that: The polyisocyanate is any one or more of toluene diisocyanate, diphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate or hexamethylene diisocyanate; And / or, the aromatic hydrocarbon solvent is any one or more of aromatic hydrocarbon S-100, aromatic hydrocarbon S-150, aromatic hydrocarbon S-180 or aromatic hydrocarbon S-200.

4. The cold box binder according to claim 1, characterized in that, The preparation method of the aluminosilicate particle-modified phenolic resin includes the following steps: S1. Mix and stir phenol, aqueous formaldehyde solution and alkali catalyst until dissolved uniformly to obtain a mixed solution system; S2. Heat the mixed solution system to 60-65°C, add aluminosilicate particles, stir evenly and keep warm for 1-2 h, then heat to 80-85°C and keep warm for 1-2 h to obtain a brown liquid, and carry out vacuum distillation to obtain aluminosilicate particle-modified phenolic resin.

5. The cold box binder according to claim 4, characterized in that: The alkali catalyst is any one or more of Ca(OH)2, LiOH·H2O, NaOH or KOH; And / or, the molar ratio of phenol, formaldehyde and alkali catalyst is 1:2-2.8:0.04-0.06, and the concentration of the aqueous formaldehyde solution is 37 wt%; And / or, the mass ratio of the mixed solution system to the aluminosilicate particles is 100:3 to 6.

6. The cold box binder according to claim 4, characterized in that: The preparation method of the aluminosilicate particles includes the following steps: S11. Dissolve aluminum chloride hexahydrate in water, stir until completely dissolved, then add aluminum powder, and heat and reflux at 80-90°C for 3-5 h to obtain aluminosilicate sol; S12. Add PVP to ethanol with a concentration of 0.5-1 wt% CaCl2, stir to dissolve to obtain a PVP solution with a concentration of 5-10 wt%, then add silane coupling agent microcapsules, stir and react evenly, and then add to the aluminosilicate sol and stir and mix evenly to obtain a mixed aluminosilicate sol; S13. Disperse the mixed aluminosilicate sol by high-speed stirring into vegetable oil containing Tween 80 to form a sol microemulsion, filter and dry to obtain aluminosilicate particles.

7. The cold box binder according to claim 6, characterized in that: The molar ratio of aluminum chloride hexahydrate to aluminum powder is 1:2-4.5; And / or, the volume ratio of the silane coupling agent microcapsules, PVP solution and aluminosilicate sol is 3-5:30:50-60; And / or, the rotation speed of the high-speed stirring is 2000-5000 r / min.

8. The cold box binder according to claim 6, characterized in that: The preparation method of the silane coupling agent microcapsules is: S21. Dissolve sodium alginate and starch in water to obtain a sodium alginate-starch dispersion; S22. Add the core material silane coupling agent to the sodium alginate-starch dispersion liquid, disperse the mixture at a high speed of 4000-6000 r / min to form an oil-in-water emulsion, and finally spray-dry the emulsion to obtain silane coupling agent microcapsules.

9. The cold box binder according to claim 8, wherein: The concentration of the sodium alginate in the dispersion liquid is 1-2 wt%; and / or, the concentration of the starch in the dispersion liquid is 1.5-2.5 wt%; and / or, the silane coupling agent is any one or more of silane coupling agent KH-550, silane coupling agent KH-560, silane coupling agent KH-570 or silane coupling agent A-187.

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