Rapid heat conduction precoated sand and preparation process thereof

Abstract

The invention discloses quick heat-conducting precoated sand and a preparation process thereof, and relates to the technical field of precoated sand, the quick heat-conducting precoated sand comprises the following raw materials by weight: 100-105 parts of crude sand, 6-8 parts of a modified resin prepolymer, 2-4 parts of modified POE, 3.5-4.5 parts of a lubricant, and 3-5 parts of nano silicon nitride. The modified POE has a relatively strong high-temperature toughening effect on the modified resin prepolymer, can also form chemical crosslinking with the modified resin prepolymer, and has relatively strong compatibility with other raw materials in the precoated sand. The modified resin prepolymer is obtained by heating and ring-opening polymerization of a benzoxazine monomer obtained by reaction of 5-nitrosalicylaldehyde, 2, 4-bis (trifluoromethyl)-5-pyrimidinyl ethyl formate, paraformaldehyde, furfuryl amine and the like, the curing temperature of the modified resin prepolymer is reduced, the thermal stability is improved, and improvement of the high temperature resistance of the precoated sand is facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coated sand, in particular to a rapid heat-conducting coated sand and a preparation process thereof. BACKGROUND

[0002] The rapid heat-conducting coated sand is a special material used for temperature control in rapid packaging, which can ensure that electronic products, medicines, food and the like are in a suitable temperature environment during transportation. The heat-conducting coated sand is usually prepared by taking natural quartz sand as a base material, coating a resin film on the surface of the base material, and adding curing agents, lubricants, and toughening and reinforcing additives.

[0003] In the heat-conducting coated sand, the resin needs to have good mechanical properties and high-temperature resistance to ensure the stability and reliability of the coated sand in a high-temperature environment. However, the brittleness of polybenzoxazine resin is enhanced at high temperatures, which may cause cracking and breaking of the coated sand at high temperatures, thereby affecting the service performance and service life thereof. POE material can be used for toughening modification of polybenzoxazine resin, but the heat resistance of POE is insufficient, the high-temperature toughening effect of POE on polybenzoxazine resin is insufficient, and the compatibility of POE and polybenzoxazine resin needs to be improved. Polybenzoxazine resin can be obtained by thermal activation ring-opening polymerization of benzoxazine monomer, and the six-membered heterocyclic oxazine ring in the benzoxazine monomer has high stability, which causes the curing temperature of traditional polybenzoxazine resin to be as high as 250 DEG C. However, this temperature may cause evaporation of benzoxazine monomer or degradation of the resin. Although the use of a catalyst can reduce the curing temperature of polybenzoxazine resin, it will have a negative impact on high-temperature resistance, which limits the use of traditional polybenzoxazine resin in coated sand.

[0004] Therefore, a suitable modification method is needed to improve the heat resistance of POE material, enhance the compatibility of POE material and polybenzoxazine resin, reduce the curing temperature of polybenzoxazine resin while ensuring high-temperature resistance, and be applied in the preparation of coated sand to obtain rapid heat-conducting coated sand with excellent mechanical strength, high-temperature resistance and the like. SUMMARY

[0005] In order to solve the above technical problems, the present application provides a rapid heat-conducting coated sand and a preparation process thereof.

[0006] The purpose of the present application can be achieved by the following technical solutions: A rapid heat-conducting coated sand, comprising the following raw materials by weight: 100-105 parts of raw sand, 6-8 parts of modified resin prepolymer, 2-4 parts of modified POE, 3.5-4.5 parts of lubricant, and 3-5 parts of nano silicon nitride. Further, the raw sand is obtained by mixing quartz sand and ceramsite sand at a mass ratio of 1-1.5:0.5-1, and the particle size of the quartz sand and the ceramsite sand is 50-70 mesh; the lubricant is obtained by mixing zinc stearate and calcium stearate at a mass ratio of 1:1.5-2; The preparation of the rapid heat-conducting precoated sand comprises the following steps: The raw sand is dried to obtain dried raw sand for standby; the modified resin prepolymer and the modified POE are mixed under heating and stirring, and then the nano silicon nitride is added and continuously stirred; the temperature is lowered to add the raw sand and half of the lubricant, and then the mixing is continuously carried out; the speed is reduced, and then the temperature is raised for solidification; the remaining lubricant is added and continuously mixed; cooling and sieving are carried out to obtain the rapid heat-conducting precoated sand; The preparation of the rapid heat-conducting precoated sand comprises the following specific steps: The raw sand is dried at 100-110℃ for 3-4h to obtain dried raw sand for standby; the modified resin prepolymer and the modified POE are mixed under stirring at a temperature of 90-100℃ and a speed of 1000-1200rpm for 0.5-1h; the nano silicon nitride is added and continuously stirred for 20-30min; the temperature is lowered to 60-80℃; the raw sand and half of the lubricant are added and continuously mixed for 25-35min; the speed is reduced to 500-600rpm; the temperature is raised to 155-165℃; stirring is carried out for 4-4.5h; the remaining lubricant is added and continuously mixed for 10-15min; cooling and sieving through a 90-110 mesh sieve are carried out to obtain the rapid heat-conducting precoated sand; The preparation of the modified POE comprises the following steps: Step A1, the vinyl siloxane and toluene are mixed and stirred, then the meta-chloro peroxo benzoic acid is added, and the temperature is raised for stirring to obtain product a1; the azaspirocyclic carboxylic acid, toluene and DMF are mixed and stirred in a protective gas atmosphere, then the temperature is raised, and the product a1 and 4-dimethylaminopyridine are added under stirring, then the temperature is raised again after stirring, and stirring is carried out to obtain product a2; Step A2, the vinylbenzoic acid and DMAC are mixed and stirred, then placed in an ice water bath, and the oxalyl chloride is added dropwise; after the dropwise addition is completed, the temperature is raised for stirring to obtain product a3; the product a2, potassium carbonate and pyridine are added in DMSO and stirred, then the solution of product a3 is added dropwise under ice water bath, and then the temperature is raised for stirring to obtain product a4; Step A3, the product a4, toluene and ethyl acetate are mixed and stirred, then the safety powder and sodium bicarbonate are added, the temperature is raised for refluxing and stirring to obtain product a5; the product a5, triphosgene, toluene and cyclohexane are mixed, protective gas is introduced, the temperature is raised for stirring, and refluxing and stirring are carried out to obtain product a6; Step A4, the POE and toluene are mixed and stirred, then the product a6, ethyl acetate and initiator are added, and continuous stirring is carried out, then the temperature is raised for refluxing and stirring to obtain the modified POE; The preparation of the modified POE comprises the following specific steps: Step A1, the vinyl siloxane, toluene were mixed and stirred for 20-25 min, and m-chloroperbenzoic acid was added. The temperature was raised to 70-80 °C, and the reaction was stirred for 8-8.5 h to obtain product a1. The azaspirocyclic carboxylic acid, toluene, DMF were mixed and stirred for 30-40 min in a protective gas atmosphere, and the temperature was raised to 55-65 °C. The product a1 and 4-dimethylaminopyridine were added with stirring, and the reaction was stirred for 6-6.5 h. The temperature was then raised to 100-105 °C, and the stirring was continued for 1.5-2 h to obtain product a2. Further, the amount ratio of the vinyl siloxane, toluene, m-chloroperbenzoic acid was 28-30 g: 115-125 mL: 25-27 g; the vinyl siloxane was 1,5-diethenylhexamethyltrisiloxane; the amount ratio of the azaspirocyclic carboxylic acid, toluene, DMF, product a1, 4-dimethylaminopyridine was 18-20 g: 75-85 mL: 40-50 mL: 31-33 g: 2.8-3.2 g; the azaspirocyclic carboxylic acid was 2-methyl-2-azaspiro[3.3]heptane-6-carboxylic acid; During the reaction of step A1, the carbon-carbon double bond of the vinyl siloxane was oxidized to an epoxy group to obtain product a1. The azaspirocyclic carboxylic acid reacted with the epoxy group of product a1 to open the ring and obtain product a2 containing a hydroxyl group. Step A2, the vinylbenzoic acid and DMAC were mixed and stirred for 15-20 min, and placed in an ice water bath. Oxalyl chloride was added dropwise. After the addition was completed, the temperature was raised to 55-65 °C, and the reaction was stirred for 1.5-2 h to obtain product a3. The product a2, potassium carbonate, and pyridine were added to DMSO and stirred for 30-40 min. The solution of product a3 was added dropwise under ice water bath, and then the temperature was raised to 50-55 °C. The reaction was stirred for 8.5-9 h to obtain product a4. Further, the amount ratio of the vinylbenzoic acid, DMAC, and oxalyl chloride was 23-25 g: 90-100 mL: 19-21 g; the vinylbenzoic acid was 3-nitro-4-vinylbenzoic acid; the amount ratio of the product a2, potassium carbonate, pyridine, DMSO, and the solution of product a3 was 35-37 g: 14.5-15.5 g: 0.2-0.4 g: 100-110 mL: 85-95 mL; the solution of product a3 was obtained by adding 26-28 g of product a3 to 55-65 mL of DMAC and stirring to mix; During the reaction of step A2, the vinylbenzoic acid reacted with oxalyl chloride to obtain product a3 containing an acyl chloride. The product a3 reacted with the hydroxyl group of product a2 to obtain an esterification product containing a nitro group, i.e. product a4. Step A3, the product a4, toluene, ethyl acetate are mixed and stirred for 15-25 min, then the safety powder, sodium bicarbonate are added, the temperature is raised to 70-80 DEG C, reflux stirring 6.5-7 h, the product a5 is obtained; the product a5, triphosgene, toluene, cyclohexane are mixed, the protective gas is introduced, the temperature is raised to 100-110 DEG C, reflux stirring 4.5-5 h, the product a6 is obtained; Further, the product a4, toluene, ethyl acetate, safety powder, sodium bicarbonate are used in the ratio of 54-56 g: 90-100 mL: 70-80 mL: 27-29 g: 0.9-1.1 g; the product a5, triphosgene, toluene, cyclohexane are used in the ratio of 51-53 g: 45-47 g: 110-120 mL: 90-100 mL; In the process of step A3 reaction, the nitro group of product a4 is selectively reduced to amino group, and the terminal carbon-carbon double bond is retained, to obtain product a5; the amino group in product a5 reacts with triphosgene to form chloroamide, and then the chlorohydrate is removed by heating to form isocyanate group, which is product a6; Step A4, POE, toluene are mixed and stirred for 40-50 min, then the product a6, ethyl acetate, initiator are added, continue to stir for 30-40 min, reflux stirring at 125-135 DEG C for 6.5-7 h, to obtain modified POE; Further, the POE, toluene, product a6, ethyl acetate, initiator are used in the ratio of 100-110 g: 210-220 mL: 10.5-11.5 g: 25-35 mL: 0.65-0.75 g; the initiator is a mixture of benzoyl peroxide and azobisisobutyronitrile in the mass ratio of 1.5-2: 1-1.5; the POE is ethylene-1-butene copolymer; In the process of step A4 reaction, the product a6 is grafted with POE to obtain modified POE containing siloxane segment, nitrogen heterospiro ring and isocyanate group; The preparation of the modified resin prepolymer comprises the following steps: Step B1, after salicylaldehyde, hydroxylamine-O-sulfonic acid, acetic acid are mixed and stirred, deionized water is added, heated and refluxed, and then treated to obtain product b1; in the protective gas atmosphere, product b1, toluene, acetonitrile are mixed and stirred, then sodium bisulfite and sodium carbonate are added after heating, and product b2 is obtained by stirring; Step B2, in the protective gas atmosphere, pyrimidine formate, DMF are mixed and stirred, then product b2, ammonium chloride are added after heating, the pH is adjusted after stirring reaction, to obtain product b3; Step B3: product b3, paraformaldehyde, 2-furfurylamine are mixed, heated and stirred, then continue to stir after heating, cool to room temperature, washed with ethyl acetate, to obtain modified resin prepolymer; The preparation of the modified resin prepolymer comprises the following specific steps: Step B1, salicylaldehyde, hydroxylamine-O-sulfonic acid, acetic acid are mixed and stirred for 10-15 min, deionized water is added, and reflux stirring is carried out at 50-60°C for 24-25 h, and the product b1 is obtained after post-treatment; in a protective gas atmosphere, the product b1, toluene, acetonitrile are mixed and stirred for 35-45 min, and the temperature is raised to 40-45°C, sodium bisulfite and sodium carbonate are added, and stirring reaction is carried out to obtain the product b2; Further, the amount ratio of salicylaldehyde, hydroxylamine-O-sulfonic acid, acetic acid, deionized water is 18-20 g:14-16 g:6.5-7 g:500-520 mL; salicylaldehyde is 5-nitrosalicylaldehyde; post-treatment is to add a 10-15% sodium bicarbonate solution to the reaction liquid obtained by heating reflux until no bubbles are generated, then extract with chloroform, rotary evaporate the obtained organic phase, and then wash with diethyl ether; the amount ratio of product b1, toluene, acetonitrile, sodium bisulfite, sodium carbonate is 21-23 g:60-70 mL:40-50 mL:16-18 g:1.5-2.5 g; In the process of step B1 reaction, the aldehyde group of salicylaldehyde reacts with hydroxylamine-O-sulfonic acid to convert the aldehyde group into a cyano group to obtain product b1; the nitro group of product b1 is selectively reduced to an amino group while the cyano group is retained to obtain product b2; Step B2, in a protective gas atmosphere, pyrimidine formate, DMF are mixed and stirred for 35-45 min, product b2, ammonium chloride are added at 80-85°C, and stirring reaction is carried out for 8-8.5 h, and the pH is adjusted to neutral to obtain product b3; Further, the amount ratio of pyrimidine formate, DMF, product b2, ammonium chloride is 33-35 g:110-120 mL:18-20 g:1-3 g; pyrimidine formate is 2,4-bistrifluoromethyl-5-pyrimidine formate; In the process of step B2 reaction, the amino group of product b2 reacts with the ester group of pyrimidine formate to obtain product b3 containing trifluoromethyl, pyrimidine, cyano, etc; Step B3: product b3, paraformaldehyde, 2-furfurylamine are mixed, the temperature is raised to 100-105°C, stirring reaction is carried out for 4.5-5 h, then the temperature is raised to 125-135°C, and stirring is continued for 1-1.5 h, and then cooled to room temperature, washed with ethyl acetate to obtain a modified resin prepolymer; Further, the amount ratio of product b3, paraformaldehyde, 2-furfurylamine is 53-55 g:6.5-7.5 g:11-13 g; In the process of step B3 reaction, product b3, paraformaldehyde and 2-furfurylamine react to obtain a benzoxazine resin prepolymer, i.e. a modified resin prepolymer; The application discloses quick heat-conducting coated sand and a preparation process thereof.

[0007] The modified POE is obtained by grafting a product obtained by reacting 1,5-divinyl hexamethyltrisiloxane, 2-methyl-2-azaspiro[3.3]heptane-6-carboxylic acid, 3-nitro-4-vinylbenzoic acid and the like with POE. The combination of 1,5-divinyl hexamethyltrisiloxane and 2-methyl-2-azaspiro[3.3]heptane-6-carboxylic acid in the modified POE gives the modified POE strong heat resistance due to the strong thermal stability of siloxane and the strong rigidity of azaspiro ring, enhances the temperature adaptability of the modified POE in the coated sand, improves the high-temperature toughening effect of the modified POE on the modified resin prepolymer, and thus improves the thermal tensile strength and thermal bending strength of the quick heat-conducting coated sand. The use of 3-nitro-4-vinylbenzoic acid in the reaction of the modified POE helps to introduce isocyanate groups into the modified POE, helps to form chemical cross-linking between the modified POE and the modified resin prepolymer, and helps to enhance the compatibility of the modified POE with other raw materials in the coated sand, and thus improves the comprehensive performance of the coated sand.

[0008] The modified resin prepolymer is obtained by ring-opening polymerization of a benzoxazine monomer obtained by reacting 5-nitrosalicylaldehyde, 2,4-bistrifluoromethyl-5-ethyl pyrimidine carboxylate, paraformaldehyde and 2-furfurylamine. The combination of 5-nitrosalicylaldehyde and 2,4-bistrifluoromethyl-5-ethyl pyrimidine carboxylate makes the product as a phenol source contain trifluoromethyl, pyrimidine ring and cyano with strong electron-withdrawing ability, helps to produce a phenolic substance with stronger acidity, and thus produces stronger catalytic ring-opening effect in the molecule, reduces the curing temperature of the modified resin prepolymer, improves the thermal stability of the modified resin prepolymer, and helps to improve the high-temperature resistance of the coated sand. Moreover, the cyano is converted into a triazine ring in the curing process of the modified resin prepolymer, and cooperates with the pyrimidine ring to improve the flame retardance of the modified resin prepolymer. DETAILED DESCRIPTION

[0009] The technical solutions in the embodiments of the application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the application.

[0010] Embodiment 1 A modified POE, the preparation of which comprises the following steps: Step A1, 1, 5-divinyl hexamethyl trisiloxane, toluene were mixed and stirred for 20 min, m-chloroperbenzoic acid was added, the temperature was raised to 70℃, and the reaction was stirred for 8 h to obtain product a1; 2-methyl-2-azaspiro[3.3]heptane-6-carboxylic acid, toluene, DMF were mixed and stirred for 30 min under nitrogen atmosphere, the temperature was raised to 55℃, product a1, 4-dimethylaminopyridine were added with stirring, the reaction was stirred for 6 h, and then the temperature was raised to 100℃, and the reaction was stirred for 1.5 h to obtain product a2; the amount ratio of 1, 5-divinyl hexamethyl trisiloxane, toluene, m-chloroperbenzoic acid was 28 g: 115 mL: 25 g; the amount ratio of 2-methyl-2-azaspiro[3.3]heptane-6-carboxylic acid, toluene, DMF, product a1, 4-dimethylaminopyridine was 18 g: 75 mL: 40 mL: 31 g: 2.8 g; Step A2, 3-nitro-4-vinylbenzoic acid, DMAC were mixed and stirred for 15 min, and placed in an ice water bath, oxalyl chloride was added dropwise, after the addition was completed, the temperature was raised to 55℃, and the reaction was stirred for 1.5 h to obtain product a3; product a2, potassium carbonate, pyridine were added to DMSO and stirred for 30 min, a solution of product a3 was added dropwise under ice water bath, and then the temperature was raised to 50℃, and the reaction was stirred for 8.5 h to obtain product a4; the amount ratio of 3-nitro-4-vinylbenzoic acid, DMAC, oxalyl chloride was 23 g: 90 mL: 19 g; the amount ratio of product a2, potassium carbonate, pyridine, DMSO, a solution of product a3 was 35 g: 14.5 g: 0.2 g: 100 mL: 85 mL; the solution of product a3 was obtained by mixing and stirring 26 g of product a3 in 55 mL of DMAC; Step A3, product a4, toluene, ethyl acetate were mixed and stirred for 15 min, safety powder, sodium bicarbonate were added, the temperature was raised to 70℃, and the reaction was stirred for 6.5 h to obtain product a5; product a5, triphosgene, toluene, cyclohexane were mixed, nitrogen was introduced, the temperature was raised to 100℃, and the reaction was stirred for 4.5 h to obtain product a6; the amount ratio of product a4, toluene, ethyl acetate, safety powder, sodium bicarbonate was 54 g: 90 mL: 70 mL: 27 g: 0.9 g; the amount ratio of product a5, triphosgene, toluene, cyclohexane was 51 g: 45 g: 110 mL: 90 mL; Step A4, POE, toluene were mixed and stirred for 40 min, product a6, ethyl acetate, initiator were added, and the stirring was continued for 30 min, and then the reaction was stirred for 6.5 h at 125℃ under reflux to obtain modified POE; the amount ratio of POE, toluene, product a6, ethyl acetate, initiator was 100 g: 210 mL: 10.5 g: 25 mL: 0.65 g; the initiator was obtained by mixing benzoyl peroxide and azobisisobutyronitrile in a mass ratio of 1.5: 1; POE was ethylene-1-butene copolymer (supplier: Jiangsu Loujiang New Material Co., Ltd.).

[0011] Example 2 A modified POE, the preparation comprising the following steps: Step A1, 1,5-divinyl hexamethyl trisiloxane, toluene were mixed and stirred for 23 min, m-chloroperbenzoic acid was added, the temperature was raised to 75°C, and stirring was carried out for 8.3 h to obtain product a1; 2-methyl-2-azaspiro[3.3]heptane-6-carboxylic acid, toluene, DMF were mixed and stirred for 35 min under nitrogen atmosphere, the temperature was raised to 60°C, product a1, 4-dimethylaminopyridine were added under stirring, stirring was carried out for 6.3 h, and then the temperature was raised to 103°C, and stirring was carried out for 1.8 h to obtain product a2; the amount ratio of 1,5-divinyl hexamethyl trisiloxane, toluene, m-chloroperbenzoic acid was 29 g: 120 mL: 26 g; the amount ratio of 2-methyl-2-azaspiro[3.3]heptane-6-carboxylic acid, toluene, DMF, product a1, 4-dimethylaminopyridine was 19 g: 80 mL: 45 mL: 32 g: 3.0 g; Step A2, 3-nitro-4-vinylbenzoic acid, DMAC were mixed and stirred for 18 min, and placed in an ice water bath, oxalyl chloride was added dropwise, after the dropwise addition was completed, the temperature was raised to 60°C, and stirring was carried out for 1.8 h to obtain product a3; product a2, potassium carbonate, pyridine were added into DMSO and stirred for 35 min, a solution of product a3 was added dropwise under ice water bath, and then the temperature was raised to 53°C, and stirring was carried out for 8.8 h to obtain product a4; the amount ratio of 3-nitro-4-vinylbenzoic acid, DMAC, oxalyl chloride was 24 g: 95 mL: 20 g; the amount ratio of product a2, potassium carbonate, pyridine, DMSO, a solution of product a3 was 36 g: 15.0 g: 0.3 g: 105 mL: 90 mL; the solution of product a3 was obtained by stirring and mixing 27 g of product a3 into 60 mL of DMAC; Step A3, product a4, toluene, ethyl acetate were mixed and stirred for 20 min, safety powder, sodium bicarbonate were added, the temperature was raised to 75°C, and reflux stirring was carried out for 6.8 h to obtain product a5; product a5, triphosgene, toluene, cyclohexane were mixed, nitrogen was introduced, and stirring was carried out while the temperature was raised to 105°C, and reflux stirring was carried out for 4.8 h to obtain product a6; the amount ratio of product a4, toluene, ethyl acetate, safety powder, sodium bicarbonate was 55 g: 95 mL: 75 mL: 28 g: 1.0 g; the amount ratio of product a5, triphosgene, toluene, cyclohexane was 52 g: 46 g: 115 mL: 95 mL; Step A4, POE, toluene were mixed and stirred for 45 min, then product a6, ethyl acetate, initiator were added, and stirring was continued for 35 min, then the mixture was stirred at 130 °C for 6.8 h, to obtain the modified POE; the amount ratio of POE, toluene, product a6, ethyl acetate, initiator was 105 g: 215 mL: 11.0 g: 30 mL: 0.70 g; the initiator was a mixture of benzoyl peroxide and azobisisobutyronitrile with a mass ratio of 1.8: 1.3; the POE was ethylene-1-butene copolymer (supplier: Jiangsu Loujiang New Material Co., Ltd.).

[0012] Example 3 A modified POE, the preparation comprising the following steps: Step A1, 1,5-divinylhexamethyltrisiloxane, toluene were mixed and stirred for 25 min, then m-chloroperoxybenzoic acid was added, and the temperature was raised to 80 °C, and stirring was continued for 8.5 h, to obtain product a1; 2-methyl-2-azaspiro[3.3]heptane-6-carboxylic acid, toluene, DMF were mixed and stirred for 40 min under nitrogen atmosphere, then the temperature was raised to 65 °C, and product a1, 4-dimethylaminopyridine were added with stirring, and stirring was continued for 6.5 h, then the temperature was raised to 105 °C, and stirring was continued for 2 h, to obtain product a2; the amount ratio of 1,5-divinylhexamethyltrisiloxane, toluene, m-chloroperoxybenzoic acid was 30 g: 125 mL: 27 g; the amount ratio of 2-methyl-2-azaspiro[3.3]heptane-6-carboxylic acid, toluene, DMF, product a1, 4-dimethylaminopyridine was 20 g: 85 mL: 50 mL: 33 g: 3.2 g; Step A2, 3-nitro-4-vinylbenzoic acid, DMAC were mixed and stirred for 20 min, then oxalyl chloride was added dropwise under ice water bath, then the temperature was raised to 65 °C, and stirring was continued for 2 h, to obtain product a3; product a2, potassium carbonate, pyridine were added into DMSO and stirred for 40 min, then the solution of product a3 was added dropwise under ice water bath, then the temperature was raised to 55 °C, and stirring was continued for 9 h, to obtain product a4; the amount ratio of 3-nitro-4-vinylbenzoic acid, DMAC, oxalyl chloride was 25 g: 100 mL: 21 g; the amount ratio of product a2, potassium carbonate, pyridine, DMSO, the solution of product a3 was 37 g: 15.5 g: 0.4 g: 110 mL: 95 mL; the solution of product a3 was obtained by adding 28 g of product a3 into 65 mL of DMAC and stirring; Step A3, product a4, toluene, ethyl acetate were mixed and stirred for 25 min, then safety powder, sodium bicarbonate were added, and the temperature was raised to 80°C, and reflux stirring was carried out for 7 h to obtain product a5; product a5, triphosgene, toluene, cyclohexane were mixed, nitrogen was introduced, and stirring was carried out while the temperature was raised to 110°C, and reflux stirring was carried out for 5 h to obtain product a6; the amount ratio of product a4, toluene, ethyl acetate, safety powder, sodium bicarbonate was 56 g: 100 mL: 80 mL: 29 g: 1.1 g; the amount ratio of product a5, triphosgene, toluene, cyclohexane was 53 g: 47 g: 120 mL: 100 mL; Step A4, POE, toluene were mixed and stirred for 50 min, then product a6, ethyl acetate, initiator were added, and stirring was continued for 40 min, and reflux stirring was carried out at 135°C for 7 h to obtain modified POE; the amount ratio of POE, toluene, product a6, ethyl acetate, initiator was 110 g: 220 mL: 11.5 g: 35 mL: 0.75 g; the initiator was obtained by mixing benzoyl peroxide and azobisisobutyronitrile in a mass ratio of 2:1.5; POE was ethylene-1-butene copolymer (supplier: Jiangsu Loujiang New Material Co., Ltd.).

[0013] Example 4 A modified resin prepolymer, the preparation comprising the following steps: Step B1, 5-nitrosalicylaldehyde, hydroxylamine-O-sulfonic acid, acetic acid were mixed and stirred for 10 min, then deionized water was added, and reflux stirring was carried out at 50°C for 24 h, and post-treatment was carried out to obtain product b1; product b1, toluene, acetonitrile were mixed and stirred for 35 min in a nitrogen atmosphere, then sodium bisulfite and sodium carbonate were added while stirring to obtain product b2; the amount ratio of 5-nitrosalicylaldehyde, hydroxylamine-O-sulfonic acid, acetic acid, deionized water was 18 g: 14 g: 6.5 g: 500 mL; post-treatment was carried out by adding a 10% sodium bicarbonate solution to the obtained reaction liquid under heating reflux until no bubbles were generated, then chloroform was used for extraction, and the obtained organic phase was rotary evaporated and washed with diethyl ether; the amount ratio of product b1, toluene, acetonitrile, sodium bisulfite, sodium carbonate was 21 g: 60 mL: 40 mL: 16 g: 1.5 g; Step B2, in a nitrogen atmosphere, 2,4-ditrifluoromethyl-5-pyrimidine formate, DMF were mixed and stirred for 35 min, then product b2, ammonium chloride were added while stirring at 80°C, and stirring reaction was carried out for 8 h, and the pH was adjusted to neutral to obtain product b3; the amount ratio of 2,4-ditrifluoromethyl-5-pyrimidine formate, DMF, product b2, ammonium chloride was 33 g: 110 mL: 18 g: 1 g; Step B3: product b3, paraformaldehyde, 2-furfurylamine were mixed, heated to 100°C, stirred for 4.5h, then heated to 125°C, continued to stir for 1h, cooled to room temperature, washed with ethyl acetate to obtain the modified resin prepolymer; the amount ratio of product b3, paraformaldehyde, 2-furfurylamine was 53g:6.5g:11g.

[0014] Example 5 A modified resin prepolymer, the preparation comprising the following steps: Step B1: 5-nitrosalicylaldehyde, hydroxylamine-O-sulfonic acid, acetic acid were mixed and stirred for 13min, deionized water was added, refluxed and stirred at 55°C for 24.5h, and then treated to obtain product b1; product b1, toluene, acetonitrile were mixed and stirred for 40min, heated to 43°C, sodium bisulfite and sodium carbonate were added, and stirred to obtain product b2; the amount ratio of 5-nitrosalicylaldehyde, hydroxylamine-O-sulfonic acid, acetic acid, deionized water was 19g:15g:6.8g:510mL; the post-treatment was to add a 13% sodium bicarbonate solution to the obtained reaction liquid under heating reflux until no bubbles were generated, then extracted with chloroform, and the obtained organic phase was rotary evaporated and washed with diethyl ether; the amount ratio of product b1, toluene, acetonitrile, sodium bisulfite, sodium carbonate was 22g:65mL:45mL:17g:2.0g; Step B2: under a nitrogen atmosphere, 2,4-bistrifluoromethyl-5-pyrimidine carboxylic acid ethyl ester, DMF were mixed and stirred for 40min, product b2, ammonium chloride were added at 83°C, stirred for 8.3h, and the pH was adjusted to neutral to obtain product b3; the amount ratio of 2,4-bistrifluoromethyl-5-pyrimidine carboxylic acid ethyl ester, DMF, product b2, ammonium chloride was 34g:115mL:19g:2g; Step B3: product b3, paraformaldehyde, 2-furfurylamine were mixed, heated to 100°C, stirred for 4.5h, then heated to 125°C, continued to stir for 1h, cooled to room temperature, washed with ethyl acetate to obtain the modified resin prepolymer; the amount ratio of product b3, paraformaldehyde, 2-furfurylamine was 53g:6.5g:11g.

[0015] Example 6 A modified resin prepolymer, the preparation comprising the following steps: Step B1, 5-nitrosalicylaldehyde, hydroxylamine-O-sulfonic acid, acetic acid were mixed and stirred for 15 min, deionized water was added, and stirred at 60°C under reflux for 25 h, and the product b1 was obtained by post-treatment; product b1, toluene, acetonitrile were mixed and stirred for 45 min, and heated to 45°C, sodium bisulfite and sodium carbonate were added, and stirred to obtain product b2; the amount ratio of 5-nitrosalicylaldehyde, hydroxylamine-O-sulfonic acid, acetic acid, deionized water was 20 g:16 g:7 g:520 mL; the post-treatment was that a 15% sodium bicarbonate solution was added to the obtained reaction liquid under heating reflux until no bubbles were generated, and then chloroform was extracted, and the obtained organic phase was rotary evaporated, and then washed with ether; the amount ratio of product b1, toluene, acetonitrile, sodium bisulfite, sodium carbonate was 23 g:70 mL:50 mL:18 g:2.5 g; Step B2, 2,4-bistrifluoromethyl-5-pyrimidine carboxylic acid ethyl ester, DMF were mixed and stirred for 45 min, product b2, ammonium chloride were added at 85°C, and stirred for 8.5 h, and the pH was adjusted to neutral to obtain product b3; the amount ratio of 2,4-bistrifluoromethyl-5-pyrimidine carboxylic acid ethyl ester, DMF, product b2, ammonium chloride was 35 g:120 mL:20 g:3 g; Step B3: product b3, paraformaldehyde, 2-furfurylamine were mixed, heated to 105°C, and stirred for 5 h, then heated to 135°C, and continued to stir for 1.5 h, cooled to room temperature, washed with ethyl acetate, and a modified resin prepolymer was obtained; the amount ratio of product b3, paraformaldehyde, 2-furfurylamine was 55 g:7.5 g:13 g.

[0016] Example 7 A rapid heat-conducting coated sand, comprising the following raw materials by weight: 100 parts of raw sand, 6 parts of modified resin prepolymer, 2 parts of modified POE, 3.5 parts of lubricant, and 3 parts of nano silicon nitride; the raw sand is obtained by mixing quartz sand and ceramsite sand at a mass ratio of 1:0.5, and the particle size of the quartz sand and the ceramsite sand is 50 mesh; the lubricant is obtained by mixing zinc stearate and calcium stearate at a mass ratio of 1:1.5; The preparation of the rapid heat-conducting coated sand comprises the following steps: The raw sand was dried at 100°C for 3 h to obtain dried raw sand for standby use; the modified resin prepolymer obtained in Example 4 and the modified POE obtained in Example 1 were mixed and stirred at a temperature of 90°C and a rotation speed of 1000 rpm for 0.5 h, nano silicon nitride was added, and stirring was continued for 20 min, the temperature was lowered to 60°C, the raw sand and half of the lubricant were added, and mixing was continued for 25 min, the rotation speed was reduced to 500 rpm, the temperature was raised to 155°C, and stirring was continued for 4 h, the remaining lubricant was added, and mixing was continued for 10 min, and then the mixture was cooled and sieved through a 90-mesh sieve to obtain the rapid heat-conducting coated sand.

[0017] Example 8 A rapid heat-conducting coated sand, comprising the following raw materials by weight: 103 parts of raw sand, 7 parts of modified resin prepolymer, 3 parts of modified POE, 4.0 parts of lubricant, and 4 parts of nano silicon nitride; the raw sand is obtained by mixing quartz sand and ceramsite sand in a mass ratio of 1.3:0.8, and the particle size of the quartz sand and the ceramsite sand is 60 mesh; the lubricant is obtained by mixing zinc stearate and calcium stearate in a mass ratio of 1:1.8; The preparation of the rapid heat-conducting coated sand comprises the following steps: The raw sand is dried at 105°C for 3.5h to obtain dried raw sand for standby; the modified resin prepolymer obtained in Example 5 and the modified POE obtained in Example 2 are mixed by stirring at a temperature of 95°C and a rotation speed of 1100 rpm for 0.8h, then the nano silicon nitride is added and stirring is continued for 25 min, the temperature is lowered to 70°C, the raw sand and half of the lubricant are added, and mixing is continued for 30 min, the rotation speed is lowered to 550 rpm, the temperature is raised to 160°C, and stirring is continued for 4.3h, then the remaining lubricant is added and mixing is continued for 13 min, and then cooling and sieving through a 100 mesh sieve are performed to obtain the rapid heat-conducting coated sand.

[0018] Example 9 A rapid heat-conducting coated sand, comprising the following raw materials by weight: 105 parts of raw sand, 8 parts of modified resin prepolymer, 4 parts of modified POE, 4.5 parts of lubricant, and 5 parts of nano silicon nitride; the raw sand is obtained by mixing quartz sand and ceramsite sand in a mass ratio of 1.5:1, and the particle size of the quartz sand and the ceramsite sand is 70 mesh; the lubricant is obtained by mixing zinc stearate and calcium stearate in a mass ratio of 1:2; The preparation of the rapid heat-conducting coated sand comprises the following steps: The raw sand is dried at 110°C for 4h to obtain dried raw sand for standby; the modified resin prepolymer obtained in Example 6 and the modified POE obtained in Example 3 are mixed by stirring at a temperature of 100°C and a rotation speed of 1200 rpm for 1h, then the nano silicon nitride is added and stirring is continued for 30 min, the temperature is lowered to 80°C, the raw sand and half of the lubricant are added, and mixing is continued for 35 min, the rotation speed is lowered to 600 rpm, the temperature is raised to 165°C, and stirring is continued for 4.5h, then the remaining lubricant is added and mixing is continued for 15 min, and then cooling and sieving through a 110 mesh sieve are performed to obtain the rapid heat-conducting coated sand.

[0019] Comparative Example 1 Comparing with Example 9, the 2-methyl-2-azaspiro[3.3]heptane-6-carboxylic acid in the preparation process of the modified POE is replaced by 3-succinimidyl propionic acid, and the rest is exactly the same as Example 9 to prepare the rapid heat-conducting coated sand.

[0020] Comparative Example 2 Comparing with Example 9, the 1,5-divinylhexamethyltrisiloxane in the preparation process of modified POE was replaced by ethylene glycol divinyl ether, and the rest was exactly the same as Example 9, to prepare the fast heat-conducting coated sand.

[0021] Comparative Example 3 Comparing with Example 9, the product a6 grafted with POE in the preparation process of modified POE was replaced by product a5, and the rest was exactly the same as Example 9, to prepare the fast heat-conducting coated sand.

[0022] Comparative Example 4 Comparing with Example 9, the 2,4-bistrifluoromethyl-5-ethyl pyrimidine formate in the preparation process of modified resin prepolymer was replaced by 2-cyanopyrimidine-5-carboxylic acid methyl ester, and the rest was exactly the same as Example 9, to prepare the fast heat-conducting coated sand.

[0023] Example 5 Comparing with Example 9, the 2,4-bistrifluoromethyl-5-ethyl pyrimidine formate in the preparation process of modified resin prepolymer was replaced by 4-(trifluoromethyl) benzoic acid methyl ester, and the rest was exactly the same as Example 9, to prepare the fast heat-conducting coated sand.

[0024] The fast heat-conducting coated sand prepared by the present application was further tested for effects, and the test results are as follows.

[0025] Hot tensile strength and hot bending strength: the obtained fast heat-conducting coated sand was tested according to JB / T 8583-2008; High temperature resistance time: the obtained fast heat-conducting coated sand was tested according to T / CFA 010604.1; The results are recorded in Table 1. Table 1: Test results

[0026] According to the data in Table 1, the rapid heat-conducting coated sand of the application has strong mechanical strength and high temperature resistance. It can be seen from the comparison between Example 9 and Comparative Example 1 that the 2-methyl-2-azaspiro[3.3]heptane-6-carboxylic acid in the preparation process of the modified POE is replaced by 3-succinimidyl propionic acid, the heat resistance of the modified POE decreases, the high-temperature toughening effect of the modified resin prepolymer decreases, the hot tensile strength and hot bending strength of the coated sand decrease, and the high temperature resistance time of the coated sand decreases. It can be seen from the comparison between Example 9 and Comparative Example 2 that the 1,5-divinylhexamethyltrisiloxane in the preparation process of the modified POE is replaced by ethylene glycol divinyl ether, the heat resistance of the modified POE decreases, the high-temperature toughening effect of the modified resin prepolymer decreases, the hot tensile strength and hot bending strength of the coated sand decrease, and the high temperature resistance time of the coated sand decreases. It can be seen from the comparison between Example 9 and Comparative Example 3 that the product a6 grafted with POE in the preparation process of the modified POE is replaced by product a5, the compatibility of the modified POE with the modified resin prepolymer and the like decreases, resulting in the decrease of the hot tensile strength, hot bending strength and high temperature resistance time of the coated sand. It can be seen from the comparison between Example 9 and Comparative Example 4 that the 2,4-bistrifluoromethyl-5-ethyl pyrimidine carboxylic acid in the preparation process of the modified resin prepolymer is replaced by 2-cyanopyrimidine-5-carboxylic acid methyl ester, the catalytic ring-opening effect decreases, the high temperature resistance of the modified resin prepolymer decreases, and the hot tensile strength, room temperature tensile strength, hot bending strength and high temperature resistance time of the coated sand decrease more. It can be seen from the comparison between Example 9 and Comparative Example 5 that the 2,4-bistrifluoromethyl-5-ethyl pyrimidine carboxylic acid in the preparation process of the modified resin prepolymer is replaced by 4-(trifluoromethyl)benzoic acid methyl ester, the catalytic ring-opening effect decreases, the high temperature resistance of the modified resin prepolymer decreases, and the hot tensile strength, room temperature tensile strength, hot bending strength and high temperature resistance time of the coated sand decrease more.

[0027] The above is only an example and description of the concept of the application, and those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace, as long as they do not deviate from the concept of the application or exceed the scope defined by the claims.

Claims

1. A fast thermal conductive coated sand, characterized by: The raw materials include the following parts by weight: 100-105 parts of raw sand, 6-8 parts of modified resin prepolymer, 2-4 parts of modified POE, 3.5-4.5 parts of lubricant, and 3-5 parts of nano silicon nitride; The modified POE is prepared by the following steps: Step A1: vinyl siloxane and toluene are mixed and stirred, and then m-chloroperbenzoic acid is added, and the temperature is raised with stirring to obtain product a1; azaspirocarboxylic acid, toluene, and DMF are mixed and stirred under a protective gas atmosphere, and the temperature is raised again. Product a1 and 4-dimethylaminopyridine are added while stirring, and the temperature is raised again, and the mixture is stirred to obtain product a2; Step A2: vinylbenzoic acid and DMAC were mixed and stirred, and then placed in an ice-water bath. Oxalyl chloride was added dropwise. After the addition was complete, the temperature was increased with stirring to obtain product a3. Product a2, potassium carbonate, and pyridine were added to DMSO and stirred. The solution of product a3 was then added dropwise in an ice-water bath, and then the temperature was increased with stirring to obtain product a4. Step A3: After mixing product a4, toluene, and ethyl acetate, add hydrosulfite and sodium bicarbonate, heat and reflux with stirring to obtain product a5; mix product a5, triphosgene, toluene, and cyclohexane, introduce protective gas, stir, heat, reflux and stir to obtain product a6; Step A4: After mixing POE and toluene, add product a6, ethyl acetate, and initiator, continue stirring, and then heat and reflux with stirring to obtain modified POE.

2. The fast heat-conducting coated sand according to claim 1, characterized in that: The raw sand is obtained by mixing quartz sand and ceramsite sand in a mass ratio of 1-1.5:0.5-1, and the particle size of the quartz sand and ceramsite sand is 50-70 mesh; the lubricant is obtained by mixing zinc stearate and calcium stearate in a mass ratio of 1:1.5-2.

3. The fast heat-conducting coated sand according to claim 1, characterized in that: In step A1, the vinylsiloxane is 1,5-divinylhexamethyltrisiloxane; and the azaspirocarboxylic acid is 2-methyl-2-azaspiro[3.3]heptane-6-carboxylic acid.

4. The fast heat-conducting coated sand according to claim 1, characterized in that: In step A2, the vinylbenzoic acid is 3-nitro-4-vinylbenzoic acid.

5. The fast heat-conducting coated sand according to claim 1, characterized in that: In step A2, the solution of product a3 is prepared by adding 26-28 g of product a3 to 55-65 mL of DMAC and stirring.

6. The fast heat-conducting coated sand according to claim 1, characterized in that: The preparation of the modified resin prepolymer comprises the following steps: Step B1: salicylaldehyde, hydroxylamine-O-sulfonic acid, and acetic acid are mixed and stirred, deionized water is added, and the mixture is heated under reflux with stirring, and post-treated to obtain product b1; in a protective gas atmosphere, product b1, toluene, and acetonitrile are mixed and stirred, and the temperature is increased, sodium bisulfite and sodium carbonate are added, and the mixture is stirred to obtain product b2; Step B2: In a protective gas atmosphere, pyrimidine carboxylate and DMF were mixed and stirred, and then the product b2 and ammonium chloride were added at elevated temperature. After stirring for reaction, the pH was adjusted to obtain product b3; Step B3: Mix product b3, paraformaldehyde, and 2-furfurylamine, heat and stir to react, then heat again and continue stirring, cool to room temperature, and wash with ethyl acetate to obtain a modified resin prepolymer.

7. The fast heat-conducting coated sand according to claim 6, characterized in that: In step B1, salicylaldehyde is 5-nitrosalicylicylaldehyde.

8. The fast heat-conducting coated sand according to claim 6, characterized in that: In step B2, the pyrimidine carboxylate is ethyl 2,4-ditrifluoromethyl-5-pyrimidine carboxylate; and after the reaction, the pH is adjusted to neutral.

9. A method for preparing the fast thermal conductive coated sand according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: drying raw sand to obtain dry raw sand for standby use; heating and stirring the modified resin prepolymer and modified POE, adding nano silicon nitride, continuing to stir, cooling, adding raw sand and half of the lubricant, continuing to mix, reducing the speed and then heating to solidify, adding the remaining lubricant, continuing to mix, cooling, and sieving to obtain fast thermal conductive coated sand.

10. The method for preparing fast thermal conductive coated sand according to claim 9, characterized in that: The temperature for heating and curing is 155-165℃.

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