Foam lost pattern material for cast aluminum parts and method of making same

Abstract

The application discloses a kind of foamed lost foam materials for cast aluminum parts and preparation method thereof, and relates to the technical field of foamed materials.The foamed lost foam material for cast aluminum parts prepared by the application is obtained by mixing and foaming modified polystyrene, modified carbon fiber and modified microcapsules.The modified polystyrene is obtained by grafting modified monomers to polystyrene and then grafting cyclosiloxane.The modified microcapsules are microcapsules containing foaming agent.The modified carbon fiber is carbon fiber loaded with catalyst.The foamed lost foam material for cast aluminum parts prepared by the application has good mechanical properties and thermal stability.

Description

Technical Field

[0001] The invention relates to the technical field of foam materials, in particular to a foam lost foam material for aluminum castings and a preparation method thereof. Background Art

[0002] Lost foam foam for aluminum castings is a core material in the lost foam casting process. Its function during the casting process is to form a foam pattern that is identical to the final casting shape. After being fixed in the sand mold and poured with liquid metal, the foam pattern vaporizes and disappears at high temperatures, forming a precision casting. Currently, this type of foam material primarily uses polystyrene (EPS) foam as its core raw material.

[0003] However, existing materials have significant drawbacks: First, EPS's insufficient heat resistance causes the foam to burn violently at high temperatures and produce large amounts of gas, potentially causing internal porosity, slag inclusions, or "backblast" in castings. Second, its mechanical properties are poor, with low compressive strength, making it susceptible to deformation under sand mold vibration or pressure, affecting the dimensional accuracy of castings. Furthermore, EPS combustion releases harmful gases such as styrene, as well as carbon particles, polluting the environment, and leaving residual coke that makes cleanup difficult. Therefore, the ideal foam material must possess both higher heat resistance and stronger mechanical properties to meet the precision and stability requirements of the casting process. Summary of the Invention

[0004] The purpose of the present invention is to provide a foam lost foam material for aluminum casting and a preparation method thereof, so as to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A method for preparing a foam lost foam material for aluminum castings, comprising the following steps:

[0007] (1) 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane, mercaptoethylamine, a photoinitiator, and tetrahydrofuran were mixed, irradiated under 500W ultraviolet light for 1-2 hours at a lamp distance of 10 cm, and then vacuum rotary evaporation was performed to obtain a modified monomer;

[0008] (2) Mix polystyrene, modified monomer, benzoyl peroxide, and xylene, heat to 120-130°C and react for 2-3 hours, then cool to 40-50°C, precipitate with acetone, filter, wash, and dry to obtain pre-modified polystyrene; mix pre-modified polystyrene, chloromethylheptamethylcyclotetrasiloxane, triethylamine, and toluene, react under nitrogen protection at 50-60°C for 6-8 hours, and wash and dry by vacuum rotary evaporation to obtain modified polystyrene;

[0009] (3) Pour the oil phase into the water phase at an oil-water ratio of 1:(4-6), homogenize at 1200 r / min for 10 min, then react at 300 r / min and 60-65°C for 7-9 h, cool to room temperature, filter, wash, and dry to obtain microcapsules;

[0010] (4) The carbon fiber was immersed in acetone for 48 hours, then taken out, washed and dried, and then immersed in 80°C, 98wt% concentrated nitric acid for oxidation for 4 hours, washed and dried to obtain oxidized carbon fiber. Under vacuum conditions, the oxidized carbon fiber and boron trifluoride ether were mixed in a mass ratio of 1:(5-6) for 50-60 minutes, filtered, washed and dried with anhydrous ethanol to obtain modified carbon fiber;

[0011] (5) Modified polystyrene, modified microcapsules, and modified carbon fibers are mixed and foamed in a mass ratio of 10:(0.1-0.2):(0.3-0.5) to obtain a foamed lost foam material for aluminum castings.

[0012] As an optimization, the molar ratio of 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane and mercaptoethylamine in step (1) is 1:(1.1-1.2); the mass ratio of mercaptoethylamine, photoinitiator and tetrahydrofuran is 1:(0.001-0.002):(20-30); and the photoinitiator is photoinitiator 2959.

[0013] As an optimization, the mass ratio of the polystyrene, modified monomer, benzoyl peroxide, and xylene in step (2) is 1:(0.3-0.4):(0.001-0.002):(20-30); the mass ratio of the pre-modified polystyrene, chloromethylheptamethylcyclotetrasiloxane, triethylamine, and toluene is 1:(0.3-0.4):(0.7-0.8):(20-30).

[0014] As an optimization, the aqueous phase in step (3) is obtained by mixing water, sodium chloride, sodium lauryl sulfate, sodium hydroxide, and magnesium nitrate hexahydrate in a mass ratio of 10:(2.0-2.5):(0.2-0.3):(0.1-0.12):(0.03-0.05); the oil phase is obtained by mixing acrylonitrile, methyl methacrylate, 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane, azobisisobutyronitrile, and isooctane in a mass ratio of 10:(3-4):(0.3-0.4):(0.1-0.2):(5-6).

[0015] As an optimization, the foaming process in step (5) is to pre-foam at 100°C for 2 minutes, place it in a mold after aging at room temperature for 12 hours, transfer the mold to a flat vulcanizer, foam it at 110°C for 20 minutes, and then cool it to room temperature to open the mold to obtain the foam lost foam material for cast aluminum parts.

[0016] The present invention also provides a foam lost foam material for aluminum castings prepared according to the method for preparing the foam lost foam material for aluminum castings.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The foam lost foam material for aluminum castings prepared by the present invention is obtained by mixing and foaming modified polystyrene, modified carbon fibers, modified microcapsules, and a foaming agent; the modified polystyrene is obtained by grafting a modified monomer onto polystyrene and then grafting a cyclosiloxane onto the modified monomer; the modified monomer is obtained by reacting 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane and mercaptoethylamine; the modified microcapsules are microcapsules containing a foaming agent; and the modified carbon fibers are carbon fibers loaded with a catalyst.

[0019] First, 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane and mercaptoethylamine react with thiol groups and double bonds to obtain a modified monomer with a vinyl group at one end and an amino group at the other. The monomer is then grafted onto the side chain of polystyrene under the initiation of benzoyl peroxide. The cyclosiloxane is then grafted onto the monomer through the reaction between the amino group and the chloromethyl group on chloromethylheptamethylcyclotetrasiloxane. Secondly, microcapsules encapsulating a foaming agent are prepared by polymerization and crosslinking using acrylonitrile and methyl methacrylate as monomers and 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane as a crosslinking agent. Catalyst-loaded carbon fibers are obtained by adsorbing boron trifluoride etherate on carbon fibers.

[0020] Finally, a foam lost-foam material for aluminum castings was obtained by mixed foaming of modified polystyrene, modified carbon fiber, and modified microcapsules; 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane is a monomer containing a spirocarbonate structure; after boron trifluoride ether is loaded on the surface of carbon fiber, it can gradually release boron trifluoride as the temperature rises during the foaming process, and at the same time trigger the ring-opening crosslinking of spirocarbonate and cyclosiloxane through cationic initiation, forming a gradient crosslinking network and enhancing the mechanical strength of the pore wall; the volume expansion caused by the release of ring tension during the ring opening of spirocarbonate can offset the shrinkage stress caused by traditional crosslinkers, maintain the foaming ratio and enhance the rigidity of the pore wall, while the flexible polysiloxane network generated by cross-linking of cyclosiloxane compensates for the brittleness of spirocarbonate, giving the material high resilience and heat resistance. The interpenetrating network formed by the two significantly improves the mechanical properties and thermal stability of the material through a rigid-flexible synergistic effect. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] The polystyrene used in the following examples and comparative examples is Longwang brand EPS, brand E-4S; the carbon fiber has a diameter of 150-200 nm and a length of 10-20 μm; it was purchased from Zhongke Leiming (Beijing) Technology Co., Ltd.; the photoinitiator is: photoinitiator 2959. Example 1

[0023] A method for preparing a foam lost foam material for aluminum castings, comprising the following steps:

[0024] (1) 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane, mercaptoethylamine, photoinitiator, and tetrahydrofuran were mixed and irradiated under 500W ultraviolet light for 2 hours at a lamp distance of 10 cm, and then vacuum rotary evaporation was performed to obtain a modified monomer; the molar ratio of 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane to mercaptoethylamine was 1:1.1; the mass ratio of mercaptoethylamine, photoinitiator, and tetrahydrofuran was 1:0.001:20;

[0025] (2) Polystyrene, modified monomer, benzoyl peroxide, and xylene were mixed in a mass ratio of 1:0.3:0.001:20, heated to 130°C for reaction for 3 hours, cooled to 50°C, precipitated with acetone, filtered, washed, and dried to obtain pre-modified polystyrene; pre-modified polystyrene, chloromethylheptamethylcyclotetrasiloxane, triethylamine, and toluene were mixed in a mass ratio of 1:0.3:0.7:20, reacted at 60°C under nitrogen protection for 8 hours, and washed and dried by reduced pressure rotary evaporation to obtain modified polystyrene;

[0026] (3) The oil phase was poured into the aqueous phase at an oil-water ratio of 1:4, homogenized at 1200 r / min for 10 min, then reacted at 300 r / min and 65°C for 9 h, cooled to room temperature, filtered, washed, and dried to obtain microcapsules; the aqueous phase was obtained by mixing water, sodium chloride, sodium lauryl sulfate, sodium hydroxide, and magnesium nitrate hexahydrate in a mass ratio of 10:2.0:0.2:0.1:0.03; the oil phase was obtained by mixing acrylonitrile, methyl methacrylate, 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane, azobisisobutyronitrile, and isooctane in a mass ratio of 10:3:0.3:0.1:5;

[0027] (4) The carbon fiber was immersed in acetone for 48 hours, then taken out, washed and dried, and then immersed in 80°C, 98wt% concentrated nitric acid for oxidation for 4 hours, washed and dried to obtain oxidized carbon fiber. Under vacuum conditions, the oxidized carbon fiber and boron trifluoride ether were mixed in a mass ratio of 1:5 for 60 minutes, filtered, washed and dried with anhydrous ethanol to obtain modified carbon fiber;

[0028] (5) Modified polystyrene, modified microcapsules, and modified carbon fibers were mixed and foamed in a mass ratio of 10:0.1:0.3 to obtain a foamed lost foam material for aluminum castings. The foaming process was as follows: pre-foaming at 100°C for 2 minutes, aging at room temperature for 12 hours, and then placing the mixture in a mold. The mold was transferred to a flat vulcanizer and foamed at 110°C for 20 minutes. The mixture was then cooled to room temperature before opening the mold. Example 2

[0029] A method for preparing a foam lost foam material for aluminum castings, comprising the following steps:

[0030] (1) 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane, mercaptoethylamine, photoinitiator, and tetrahydrofuran were mixed and irradiated under 500W ultraviolet light for 1.5 hours at a lamp distance of 10 cm, and then vacuum rotary evaporation was performed to obtain a modified monomer; the molar ratio of 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane to mercaptoethylamine was 1:1.15; the mass ratio of mercaptoethylamine, photoinitiator, and tetrahydrofuran was 1:0.001:25;

[0031] (2) Polystyrene, modified monomer, benzoyl peroxide, and xylene were mixed in a mass ratio of 1:0.35:0.001:25, heated to 125°C for reaction for 2.5 hours, cooled to 45°C, precipitated with acetone, filtered, washed, and dried to obtain pre-modified polystyrene; pre-modified polystyrene, chloromethylheptamethylcyclotetrasiloxane, triethylamine, and toluene were mixed in a mass ratio of 1:0.35:0.75:25, reacted at 55°C under nitrogen protection for 8 hours, and washed and dried by vacuum rotary evaporation to obtain modified polystyrene;

[0032] (3) The oil phase was poured into the aqueous phase at an oil-water ratio of 1:5, homogenized at 1200 r / min for 10 min, then reacted at 300 r / min and 53°C for 8 h, cooled to room temperature, filtered, washed, and dried to obtain microcapsules; the aqueous phase was obtained by mixing water, sodium chloride, sodium lauryl sulfate, sodium hydroxide, and magnesium nitrate hexahydrate in a mass ratio of 10:2.3:0.25:0.11:0.04; the oil phase was obtained by mixing acrylonitrile, methyl methacrylate, 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane, azobisisobutyronitrile, and isooctane in a mass ratio of 10:3.5:0.35:0.15:5.5;

[0033] (4) The carbon fiber was immersed in acetone for 48 hours, washed and dried, and then immersed in 80°C, 98wt% concentrated nitric acid for oxidation for 4 hours, washed and dried to obtain oxidized carbon fiber. Under vacuum conditions, the oxidized carbon fiber and boron trifluoride ether were mixed at a mass ratio of 1:5.5 for 55 minutes, filtered, washed and dried with anhydrous ethanol to obtain modified carbon fiber;

[0034] (5) Modified polystyrene, modified microcapsules, and modified carbon fibers were mixed and foamed in a mass ratio of 10:0.15:0.4 to obtain a foamed lost foam material for aluminum castings. The foaming process was as follows: pre-foaming at 100°C for 2 minutes, curing at room temperature for 12 hours, placing the mixture in a mold, transferring the mold to a flat vulcanizer, foaming at 110°C for 20 minutes, and then cooling the mixture to room temperature before opening the mold. Example 3

[0035] A method for preparing a foam lost foam material for aluminum castings, comprising the following steps:

[0036] (1) 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane, mercaptoethylamine, photoinitiator, and tetrahydrofuran were mixed and irradiated under 500W ultraviolet light for 1 hour at a lamp distance of 10 cm, and then the modified monomer was obtained by rotary evaporation under reduced pressure; the molar ratio of 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane to mercaptoethylamine was 1:1.2; the mass ratio of mercaptoethylamine, photoinitiator, and tetrahydrofuran was 1:0.002:30;

[0037] (2) Polystyrene, modified monomer, benzoyl peroxide, and xylene were mixed in a mass ratio of 1:0.4:0.002:30, heated to 120°C for reaction for 2 hours, cooled to 40°C, precipitated with acetone, filtered, washed, and dried to obtain pre-modified polystyrene; pre-modified polystyrene, chloromethylheptamethylcyclotetrasiloxane, triethylamine, and toluene were mixed in a mass ratio of 1:0.4:0.8:30, reacted at 50°C under nitrogen protection for 6 hours, and washed and dried by reduced pressure rotary evaporation to obtain modified polystyrene;

[0038] (3) The oil phase was poured into the aqueous phase at an oil-water ratio of 1:6, homogenized at 1200 r / min for 10 min, then reacted at 300 r / min and 60°C for 7 h, cooled to room temperature, filtered, washed, and dried to obtain microcapsules; the aqueous phase was obtained by mixing water, sodium chloride, sodium lauryl sulfate, sodium hydroxide, and magnesium nitrate hexahydrate in a mass ratio of 10:2.5:0.3:0.12:0.05; the oil phase was obtained by mixing acrylonitrile, methyl methacrylate, 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane, azobisisobutyronitrile, and isooctane in a mass ratio of 10:4:0.4:0.2:6;

[0039] (4) The carbon fiber was immersed in acetone for 48 hours, then taken out, washed and dried, and then immersed in 80°C, 98wt% concentrated nitric acid for oxidation for 4 hours, washed and dried to obtain oxidized carbon fiber. Under vacuum conditions, the oxidized carbon fiber and boron trifluoride ether were mixed in a mass ratio of 1:6 for 50 minutes, filtered, washed and dried with anhydrous ethanol to obtain modified carbon fiber;

[0040] (5) Modified polystyrene, modified microcapsules, and modified carbon fibers were mixed and foamed in a mass ratio of 10:0.2:0.5 to obtain a foamed lost foam material for aluminum castings. The foaming process was as follows: pre-foaming at 100°C for 2 minutes, curing at room temperature for 12 hours, and then placing the mixture in a mold. The mold was transferred to a flat vulcanizer and foamed at 110°C for 20 minutes. The mixture was then cooled to room temperature before opening the mold. Example 4

[0041] A method for preparing a foam lost foam material for aluminum castings, comprising the following steps:

[0042] (1) 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane, mercaptoethylamine, a photoinitiator, and tetrahydrofuran were mixed, irradiated under 500W ultraviolet light for 1-2 hours at a lamp distance of 10 cm, and then subjected to vacuum rotary evaporation to obtain a modified monomer; the molar ratio of 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane to mercaptoethylamine was 1:1.1; the mass ratio of mercaptoethylamine, photoinitiator, and tetrahydrofuran was 1:0.002:27;

[0043] (2) Polystyrene, modified monomer, benzoyl peroxide, and xylene were mixed in a mass ratio of 1:0.3:0.001:30, heated to 130°C for reaction for 2 hours, cooled to 47°C, precipitated with acetone, filtered, washed, and dried to obtain pre-modified polystyrene; pre-modified polystyrene, chloromethylheptamethylcyclotetrasiloxane, triethylamine, and toluene were mixed in a mass ratio of 1:0.3:0.8:23, reacted at 52°C under nitrogen protection for 6 hours, and washed and dried by reduced pressure rotary evaporation to obtain modified polystyrene;

[0044] (3) The oil phase was poured into the water phase at an oil-water ratio of 1:4, homogenized at 1200 r / min for 10 min, then reacted at 300 r / min and 63°C for 8 h, cooled to room temperature, filtered, washed, and dried to obtain microcapsules; the water phase was obtained by mixing water, sodium chloride, sodium lauryl sulfate, sodium hydroxide, and magnesium nitrate hexahydrate in a mass ratio of 10:2.2:0.27:0.11:0.04; the oil phase was obtained by mixing acrylonitrile, methyl methacrylate, 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane, azobisisobutyronitrile, and isooctane in a mass ratio of 10:3.2:0.3:0.1:5.7;

[0045] (4) the carbon fiber is immersed in acetone for 48 h, taken out, washed and dried, then immersed in 98 wt% concentrated nitric acid at 80℃ for 4 h, washed and dried to obtain an oxidized carbon fiber, the oxidized carbon fiber and boron trifluoride ether are mixed at a mass ratio of 1:5.7 under vacuum for 53 min, filtered, washed with anhydrous ethanol and dried to obtain a modified carbon fiber;

[0046] (5) the modified polystyrene, the modified microcapsule and the modified carbon fiber are mixed at a mass ratio of 10:0.15:0.33 to obtain a foam lost pattern material for casting aluminum parts; the foaming process is pre-foaming at 100℃ for 2 min, curing at room temperature for 12 h, then placed in a mold, the mold is transferred to a flat vulcanizing machine, foaming at 110℃ for 20 min, then cooled to room temperature, and the mold is opened to obtain the foam lost pattern material for casting aluminum parts. Example Five

[0047] A preparation method of a foam lost pattern material for casting aluminum parts, comprising the following preparation steps:

[0048] (1) 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane, mercaptoethylamine, a photoinitiator and tetrahydrofuran are mixed, and irradiated under 500W ultraviolet light for 1-2 h with a lamp distance of 10 cm to obtain a modified monomer; the molar ratio of 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane to mercaptoethylamine is 1:1.2; the mass ratio of the mercaptoethylamine, the photoinitiator and the tetrahydrofuran is 1:0.002:20;

[0049] (2) polystyrene, the modified monomer, benzoyl peroxide and dimethylbenzene are mixed at a mass ratio of 1:0.4:0.002:20, heated to 127℃ and reacted for 3 h, then cooled to 40℃, precipitated with acetone, filtered, washed and dried to obtain a pre-modified polystyrene; the pre-modified polystyrene, chloromethyl heptamethylcyclotetrasiloxane, triethylamine and toluene are mixed at a mass ratio of 1:0.4:0.7:20, reacted at 56℃ under nitrogen protection for 8 h, and then filtered, washed and dried under reduced pressure to obtain the modified polystyrene;

[0050] (3) the oil phase is poured into the water phase at an oil-water ratio of 1:5.6, homogenized at 1200 r / min for 10 min, then reacted at 63℃ under 300 r / min for 9 h, cooled to room temperature, filtered, washed and dried to obtain the microcapsule; the water phase is obtained by mixing water, sodium chloride, sodium dodecyl sulfate, sodium hydroxide and magnesium nitrate hexahydrate at a mass ratio of 10:2.5:0.3:0.1:0.03; the oil phase is obtained by mixing acrylonitrile, methyl methacrylate, 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane, azobis isobutyronitrile and isooctane at a mass ratio of 10:4:0.3:0.2:5;

[0051] (4) The carbon fiber was immersed in acetone for 48 hours, washed and dried, and then immersed in 80°C, 98wt% concentrated nitric acid for oxidation for 4 hours, washed and dried to obtain oxidized carbon fiber. Under vacuum conditions, the oxidized carbon fiber and boron trifluoride ether were mixed at a mass ratio of 1:5.7 for 53 minutes, filtered, washed and dried with anhydrous ethanol to obtain modified carbon fiber;

[0052] (5) Modified polystyrene, modified microcapsules, and modified carbon fibers were mixed and foamed in a mass ratio of 10:0.2:0.5 to obtain a foamed lost foam material for aluminum castings. The foaming process was as follows: pre-foaming at 100°C for 2 minutes, curing at room temperature for 12 hours, placing the mixture in a mold, transferring the mold to a flat vulcanizer, foaming at 110°C for 20 minutes, and then cooling to room temperature before opening the mold to obtain a foamed lost foam material for aluminum castings.

[0053] Comparative Example 1:

[0054] The preparation method of the foamed lost foam material for aluminum castings in Comparative Example 1 differs from that in Example 2 in that the polystyrene is not modified. Specifically, steps (1) to (3) are not included. Step (5) is modified as follows: polystyrene, modified microcapsules, and modified carbon fibers are uniformly mixed in a mass ratio of 10:0.15:0.4, and then added to a single-screw extruder for chemical foaming to obtain the foamed lost foam material for aluminum castings; the temperatures of the three sections of the single-screw extruder are 145, 200, and 200°C, respectively, and the screw speed is 20 r / min. The remaining steps are the same as in Example 2.

[0055] Comparative Example 2:

[0056] The preparation method of the foamed lost foam material for aluminum castings in Comparative Example 2 differs from that in Example 2 in that the carbon fibers are not modified. Specifically, step (4) is omitted. Step (5) is modified as follows: modified polystyrene, modified microcapsules, and carbon fibers are uniformly mixed in a mass ratio of 10:0.15:0.4, and then added to a single-screw extruder for chemical foaming to obtain the foamed lost foam material for aluminum castings; the temperatures of the three sections of the single-screw extruder are 145, 200, and 200°C, respectively, and the screw speed is 20 r / min. The remaining steps are the same as in Example 2.

[0057] Test Example 1:

[0058] Mechanical properties test:

[0059] Test Method: The aluminum castings produced in the Examples and Comparative Examples were prepared using lost foam foam material into 20 mm × 20 mm × 20 mm foam blocks. Compression strength testing was conducted in accordance with GB / T 8813-2008, "Determination of Compression Properties of Rigid Foam Plastics," at a test rate of 5 mm / min. The results are shown in Table 1.

[0060] Table 1

[0061]

[0062] From the comparison of the experimental data of Examples 1-3 and Comparative Examples 1-2 in Table 1, it can be found that the material prepared by the present application has good mechanical properties.

[0063] Comparative Example 1 does not modify polystyrene, and Comparative Example 2 does not modify carbon fiber. The mechanical properties of Examples 1-3 are better than those of Comparative Examples 1 and 2, indicating that the foamed lost pattern material for cast aluminum parts is obtained by mixing and foaming modified polystyrene, modified carbon fiber and modified microcapsules; 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane is a monomer containing a spiro orthocarbonate structure; after boron trifluoride ether is loaded on the surface of carbon fiber, boron trifluoride is gradually released as the temperature rises during foaming, and at the same time, the ring-opening crosslinking of spiro orthocarbonate and cyclosiloxane is triggered by cationic initiation, forming a gradient crosslinking network, enhancing the mechanical strength of the cell wall; the volume expansion caused by the release of ring tension during the ring-opening of spiro orthocarbonate can offset the shrinkage stress caused by traditional crosslinking agents, maintain the foaming ratio and enhance the rigidity of the cell wall, while the flexible polysiloxane network generated by the crosslinking of cyclosiloxane compensates for the brittleness of spiro orthocarbonate, and the interpenetrating network formed by the two significantly improves the mechanical properties of the material through the rigid-flexible synergistic effect.

[0064] Test Example 2:

[0065] Test of heat resistance:

[0066] Test method: Using a differential scanning calorimeter, under a nitrogen atmosphere, the glass transition temperature of the foamed lost pattern prepared by the examples and comparative examples was tested at a speed of 20℃ / min from room temperature to 200℃. The results are shown in Table 2.

[0067] Table 2

[0068]

[0069] From the comparison of the experimental data of Examples 1-3 and Comparative Examples 1-2 in Table 2, it can be found that the foamed lost pattern prepared by the present application has good heat resistance.

[0070] Comparative Example 1 does not modify the polystyrene, and the heat resistance of Examples 1 to 3 is better than that of Comparative Example 1, indicating that the foam lost foam material for aluminum castings is obtained by mixed foaming of modified polystyrene, modified carbon fiber, and modified microcapsules; 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane is a monomer containing a spiro orthocarbonate structure; after boron trifluoride ether is loaded on the surface of the carbon fiber, boron trifluoride can be gradually released as the temperature increases during the foaming process, and at the same time, the ring-opening crosslinking of the spiro orthocarbonate and cyclosiloxane is triggered by cationic initiation, and the flexible polysiloxane network generated by cross-linking of the cyclosiloxane gives the material high resilience and heat resistance.

[0071] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be encompassed therein. Any reference in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A method for preparing a foam lost foam material for aluminum castings, characterized in that: The method comprises the following preparation steps: (1) 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane, mercaptoethylamine, a photoinitiator, and tetrahydrofuran were mixed, irradiated under 500W ultraviolet light for 1-2 hours at a lamp distance of 10 cm, and then vacuum rotary evaporation was performed to obtain a modified monomer; (2) Mix polystyrene, modified monomer, benzoyl peroxide and xylene, heat to 120-130°C and react for 2-3 hours, then cool to 40-50°C, precipitate with acetone, filter, wash and dry to obtain pre-modified polystyrene; Pre-modified polystyrene, chloromethylheptamethylcyclotetrasiloxane, triethylamine and toluene are mixed, reacted at 50-60°C under nitrogen protection for 6-8 hours, and then washed and dried by vacuum rotary evaporation to obtain modified polystyrene; (3) Pour the oil phase into the water phase at an oil-water ratio of 1:(4-6), homogenize at 1200 r / min for 10 min, then react at 300 r / min and 60-65°C for 7-9 h, cool to room temperature, filter, wash, and dry to obtain microcapsules; (4) The carbon fiber was immersed in acetone for 48 hours, then taken out, washed and dried, and then immersed in 80°C, 98wt% concentrated nitric acid for oxidation for 4 hours, washed and dried to obtain oxidized carbon fiber. Under vacuum conditions, the oxidized carbon fiber and boron trifluoride ether were mixed in a mass ratio of 1:(5-6) for 50-60 minutes, filtered, washed and dried with anhydrous ethanol to obtain modified carbon fiber; (5) Modified polystyrene, modified microcapsules, and modified carbon fibers are mixed and foamed in a mass ratio of 10:(0.1-0.2):(0.3-0.5) to obtain a foamed lost foam material for aluminum castings.

2. The method for preparing a foamed lost foam material for aluminum casting according to claim 1, wherein: In step (1), the molar ratio of 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane to mercaptoethylamine is 1:(1.1-1.2); the mass ratio of mercaptoethylamine, photoinitiator, and tetrahydrofuran is 1:(0.001-0.002):(20-30); and the photoinitiator is photoinitiator 2959.

3. The method for preparing a foam lost foam material for aluminum casting according to claim 1, characterized in that: In step (2), the mass ratio of the polystyrene, modified monomer, benzoyl peroxide, and xylene is 1:(0.3-0.4):(0.001-0.002):(20-30); the mass ratio of the pre-modified polystyrene, chloromethylheptamethylcyclotetrasiloxane, triethylamine, and toluene is 1:(0.3-0.4):(0.7-0.8):(20-30).

4. The method for preparing a foamed lost foam material for aluminum casting according to claim 1, wherein: The aqueous phase in step (3) is obtained by mixing water, sodium chloride, sodium lauryl sulfate, sodium hydroxide, and magnesium nitrate hexahydrate in a mass ratio of 10:(2.0-2.5):(0.2-0.3):(0.1-0.12):(0.03-0.05); the oil phase is obtained by mixing acrylonitrile, methyl methacrylate, 3,9-divinyl-1,5,7,11-tetraoxa[5.5]undecane, azobisisobutyronitrile, and isooctane in a mass ratio of 10:(3-4):(0.3-0.4):(0.1-0.2):(5-6).

5. The method for preparing a foamed lost foam material for aluminum casting according to claim 1, characterized in that: The foaming process in step (5) is to pre-foam at 100°C for 2 minutes, place it in a mold after aging at room temperature for 12 hours, transfer the mold to a flat vulcanizer, foam it at 110°C for 20 minutes, and then cool it to room temperature before opening the mold to obtain the foam lost foam material for aluminum castings.

6. A foam lost foam material for aluminum castings prepared according to the method for preparing a foam lost foam material for aluminum castings according to any one of claims 1 to 5.

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