3D prints and uses high strength tectorial membrane sand
Technical Field
The invention relates to the field of precoated sand, in particular to high-strength precoated sand for 3D printing.
Background
The precoated sand is molding sand or core sand with a layer of solid resin film coated on the surface of sand before molding, and has two coating processes of a cold method and a hot method. The cold method is that the resin is dissolved by ethanol, urotropine is added in the sand mixing process to lead the resin and the urotropine to be coated on the surface of sand grains, and the ethanol is volatilized to obtain coated sand; the heat method is to preheat the sand to a certain temperature, add resin to melt the sand, stir the sand to coat the resin on the surface of the sand, add urotropine water solution and lubricant, cool, crush and screen to obtain the precoated sand. The 3D printing is a process of curing and molding the precoated sand layer by adopting gravity superposition and laser firing. Compared with the traditional precoated sand, the 3D printing precoated sand has high requirements on the flowing property, strength, pressure resistance and the like of the precoated sand, and the common precoated sand cannot meet the requirement of the existing 3D printing technology on the performance of a precoated sand material.
Disclosure of Invention
The invention aims to provide high-strength precoated sand for 3D printing, which has high strength, good fluidity and good bonding effect.
The invention adopts the following technical scheme:
the high-strength precoated sand for 3D printing is prepared from the following raw materials in parts by weight: 100-200 parts of crude sand, 5-10 parts of coupling agent, 2-5 parts of dispersing agent, 3-6 parts of catalyst, 2-4 parts of lubricant, 30-60 parts of resin, 20-30 parts of curing agent, 10-20 parts of high-temperature resistant agent, 8-12 parts of dispersing agent and 6-8 parts of reinforcing agent; wherein the raw sand is obtained by uniformly mixing quartz sand, chromite sand, magnesia sand and zircon sand according to the mass ratio of 6-8:4-6:5-7: 5-9;
the method for preparing the 3D printing high-strength precoated sand comprises the following steps:
(1) preparing raw sand: cleaning quartz sand, chromite sand, magnesia sand and zircon sand with clear water respectively, soaking in an acid solution after cleaning, taking out, drying in a dryer at the drying temperature of 100-200 ℃, firing in a high-temperature furnace, cooling to room temperature after firing, taking out, adding the materials into a ball mill respectively, grinding into particles with the particle size of 200-300 meshes, and mixing the quartz sand, the chromite sand, the magnesia sand and the zircon sand uniformly according to the mass ratio of 6-8:4-6:5-7:5-9 to obtain raw sand;
(2) modifying raw sand: adding 200 parts of the raw sand obtained in the step (1), 5-10 parts of coupling agent, 2-5 parts of dispersing agent, 3-6 parts of catalyst and 2-4 parts of lubricating agent into a mixer, stirring at high speed for 20-30min, adjusting the mixer to stir at low speed for 1-2h when the temperature of materials in the mixer reaches 120-180 ℃, then adding 30-60 parts of resin, and starting high-speed stirring for 1-5min after complete addition to obtain modified raw sand;
(3) preparing precoated sand: when the temperature of the modified raw sand in the mixer in the step (2) is reduced to 150 ℃ below 0 ℃, adding 20-30 parts of curing agent, 10-20 parts of high-temperature resistant agent, 8-12 parts of dispersing agent and 6-8 parts of reinforcing agent into the mixer, stirring at high speed for 10-20min, and taking out after the material is cooled;
(4) crushing and packaging: adding the material obtained in the step (3) into a crusher to be crushed into particles with the particle size of 200-300 meshes, cooling to room temperature, taking out and packaging to obtain high-strength precoated sand;
wherein the high-speed stirring speed of the mixer is 300-400rpm, and the low-speed stirring speed is 200-300 rpm.
Furthermore, the granularity of the coated sand is 200-300 meshes.
Furthermore, the granularity of the raw sand is 200-300 meshes.
Further, the resin is one or more of phenolic resin, urea resin, epoxy resin and polyester polyol.
Further, the precoated sand is used as molding sand for 3D printing rapid prototyping.
Further, the concentration of the acid solution in the step (1) is 1-10mol/L, and the soaking time is 2-5 h.
Further, the temperature of the high-temperature furnace in the step (1) is 900-.
The high-strength precoated sand for 3D printing has the following beneficial effects:
(1) according to the high-strength precoated sand for 3D printing, the resin is added in the raw sand modification process and stirred and mixed at a high speed, and then the curing agent and the like are added to prepare the precoated sand, so that the resin and the raw sand are connected in a key connection mode in the stirring process, the conventional coating connection mode between the raw sand and the resin is changed, the bonding point strength of the raw sand and the resin is enhanced, the strength of the precoated sand is further greatly improved, the normal-temperature tensile strength of the precoated sand reaches 5-7.5MPa, and the bending strength of the precoated sand reaches 3-4MPa, compared with the commercially available common precoated sand, the strength is greatly improved, the quality of 3D printing molding sand is improved, the molding sand can well adapt to the requirements of various 3D printing products, and the application range of the molding sand is expanded.
(2) In the high-strength precoated sand for 3D printing, chromite sand, magnesia and zircon sand with good heat conduction and heat dissipation effects are used as part of raw sand, and a high-temperature resistant agent is added in the preparation process, so that the high-temperature resistance of the precoated sand is improved; meanwhile, the possibility that amine compounds decomposed by urotropine are decomposed into atomic nitrogen is reduced, and the surface glossiness of the precoated sand is improved.
(3) In the high-strength precoated sand for 3D printing, raw materials such as a dispersing agent, a lubricating agent and the like are added in the process of modifying raw sand, so that the flowability of the precoated sand is improved to 4.5-7.5cm/min, and is remarkably improved compared with the flowability of 1.2cm/min of common precoated sand sold in the market, the high-strength precoated sand is stable in property, tiny parts can be printed by using the precoated sand, and the high-strength precoated sand is good in product strength and high in precision.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to specific experimental data, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The high-strength precoated sand for 3D printing is prepared from the following raw materials in parts by weight: 100 parts of raw sand, 5 parts of diphenylmethane diisocyanate, 2 parts of oxidized polyethylene wax, 3 parts of sodium thiosulfate, 2 parts of stearic alcohol, 30 parts of phenolic resin, 20 parts of urotropine with the concentration of 10-60%, 10 parts of asbestos fiber, 8 parts of potassium chromate and 6 parts of methyl methacrylate resin; wherein the raw sand is obtained by uniformly mixing quartz sand, chromite sand, magnesia and zircon sand according to the mass ratio of 6:4:5: 5.
The preparation method of the precoated sand in the embodiment adopts the following steps:
(1) preparing raw sand: respectively cleaning quartz sand, chromite sand, magnesia sand and zircon sand with clear water, soaking the cleaned quartz sand, chromite sand, magnesia sand and zircon sand in 1mol/L acid solution for 5 hours, taking out the cleaned quartz sand, chromite sand, magnesia sand and zircon sand, drying the cleaned quartz sand in a dryer at the drying temperature of 100 ℃, then putting the dried quartz sand, chromite sand, magnesia sand and zircon sand into a high-temperature furnace for firing, cooling the quartz sand, chromite sand, magnesia sand and zircon sand to the room temperature after firing, taking out the quartz sand, chromite sand, magnesia sand and zircon sand after firing, respectively adding the quartz sand, chromite sand, magnesia sand and zircon sand into a ball mill, grinding the mixture into particles with the particle size of 200 plus 300 meshes, and;
(2) modifying raw sand: adding 100 parts of raw sand obtained in the step (1), 5 parts of diphenylmethane diisocyanate, 2 parts of oxidized polyethylene wax, 3 parts of sodium thiosulfate and 2 parts of stearic alcohol into a mixer, stirring at a high speed of 400rpm for 20min, adjusting the mixer to stir at a low speed for 2h when the temperature of materials in the mixer reaches 120 ℃, adding 30 parts of phenolic resin at a low stirring speed of 200rpm, and starting high-speed stirring for 5min after complete addition to obtain modified raw sand;
(3) preparing precoated sand: when the temperature of the modified raw sand in the mixer in the step (2) is reduced to 120 ℃, adding 20 parts of urotropine with the concentration of 10-60%, 10 parts of asbestos fiber, 8 parts of potassium chromate and 6 parts of methyl methacrylate resin into the mixer, stirring at a high speed for 20min, and taking out after the materials are cooled;
(4) crushing and packaging: and (4) adding the material obtained in the step (3) into a crusher to be crushed into particles with the particle size of 200-300 meshes, cooling to room temperature, taking out and packaging to obtain the high-strength precoated sand.
Example 2
The high-strength precoated sand for 3D printing is prepared from the following raw materials in parts by weight: 200 parts of raw sand, 10 parts of toluene diisocyanate, 5 parts of hydroxystearic acid, 6 parts of potassium thiosulfate, 4 parts of stearic acid amide, 60 parts of urea-formaldehyde resin, 30 parts of urotropin with the concentration of 10-60%, 20 parts of glass fiber, 12 parts of manganese dioxide and 8 parts of vinyl acetate resin; wherein the raw sand is obtained by uniformly mixing quartz sand, chromite sand, magnesia and zircon sand according to the mass ratio of 8:6:7: 9.
The preparation method of the precoated sand in the embodiment adopts the following steps:
(1) preparing raw sand: respectively cleaning quartz sand, chromite sand, magnesia sand and zircon sand with clear water, soaking the cleaned quartz sand, chromite sand, magnesia sand and zircon sand in an acid solution with the concentration of 10mol/L for 2 hours, taking out the cleaned quartz sand, chromite sand, magnesia sand and zircon sand, drying the cleaned quartz sand in a dryer at the drying temperature of 200 ℃, then putting the dried quartz sand, chromite sand, magnesia sand and zircon sand into a high-temperature furnace for firing, cooling the quartz sand, chromite sand, magnesia sand and zircon sand to room temperature after firing, taking out the quartz sand, chromite sand, magnesia sand and zircon sand, respectively adding the above materials into a ball mill, grinding the mixture into particles with the particle size of 200 meshes and 300 meshes, and finally uniformly mixing the quartz sand;
(2) modifying raw sand: adding 200 parts of the raw sand obtained in the step (1), 10 parts of toluene diisocyanate, 5 parts of hydroxy stearic acid, 6 parts of potassium thiosulfate and 4 parts of stearic acid amide into a mixer, stirring at a high speed of 300rpm for 30min, adjusting the mixer to stir at a low speed for 1h when the temperature of materials in the mixer reaches 180 ℃, adding 60 parts of urea-formaldehyde resin at a low stirring speed of 300rpm, and starting high-speed stirring for 1min after complete addition to obtain modified raw sand;
(3) preparing precoated sand: when the temperature of the modified raw sand in the mixer in the step (2) is reduced to 150 ℃, adding 30 parts of urotropine with the concentration of 10-60%, 20 parts of glass fiber, 12 parts of manganese dioxide and 8 parts of vinyl acetate resin into the mixer, stirring at high speed for 10min, and taking out after the materials are cooled;
(4) crushing and packaging: and (4) adding the material obtained in the step (3) into a crusher to be crushed into particles with the particle size of 200-300 meshes, cooling to room temperature, taking out and packaging to obtain the high-strength precoated sand.
Example 3
The high-strength precoated sand for 3D printing is prepared from the following raw materials in parts by weight: 150 parts of raw sand, 7 parts of isophorone, 4 parts of butyl stearate, 5 parts of potassium permanganate, 3 parts of stearic acid, 40 parts of epoxy resin, 25 parts of urotropine with the concentration of 10-60%, 15 parts of graphene, 10 parts of potassium dichromate and 7 parts of ethyl methacrylate resin; wherein the raw sand is prepared by uniformly mixing quartz sand, chromite sand, magnesia and zircon sand according to the mass ratio of 7:5:6: 7.
The preparation method of the precoated sand in the embodiment adopts the following steps:
(1) preparing raw sand: respectively cleaning quartz sand, chromite sand, magnesia sand and zircon sand with clear water, soaking the cleaned quartz sand, chromite sand, magnesia sand and zircon sand in an acid solution with the concentration of 5mol/L for 4 hours, taking out the cleaned quartz sand, chromite sand, magnesia sand and zircon sand, drying the cleaned quartz sand in a dryer at the drying temperature of 120 ℃, putting the dried quartz sand, chromite sand, magnesia sand and zircon sand into a high-temperature furnace, firing the quartz sand, chromite sand, magnesia sand and zircon sand at the firing time of 12 hours at the high-temperature furnace temperature of 1200 ℃, cooling the quartz sand to room temperature after firing, taking out the quartz sand, chromite sand, magnesia sand and zircon sand, respectively adding the quartz sand, chromite sand, magnesia sand and zircon sand into;
(2) modifying raw sand: adding 150 parts of the raw sand obtained in the step (1), 7 parts of isophorone, 4 parts of butyl stearate, 5 parts of potassium permanganate and 3 parts of stearic acid into a mixer, stirring at a high speed of 360rpm for 25min, adjusting the mixer to stir at a low speed for 1.5h when the temperature of materials in the mixer reaches 160 ℃, adding 40 parts of epoxy resin at a low stirring speed of 250rpm, and starting high-speed stirring for 4min after complete addition to obtain modified raw sand;
(3) preparing precoated sand: when the temperature of the modified raw sand in the mixer in the step (2) is reduced to 140 ℃, adding 25 parts of urotropine with the concentration of 10-60%, 15 parts of graphene, 10 parts of potassium dichromate and 7 parts of ethyl methacrylate resin into the mixer, stirring at a high speed for 16min, and taking out after the materials are cooled;
(4) crushing and packaging: and (4) adding the material obtained in the step (3) into a crusher to be crushed into particles with the particle size of 200-300 meshes, cooling to room temperature, taking out and packaging to obtain the high-strength precoated sand.
Example 4
The high-strength precoated sand for 3D printing is prepared from the following raw materials in parts by weight: 120 parts of raw sand, 5 parts of hexamethylene diisocyanate, 3 parts of stearyl alcohol, 3 parts of sodium hypochlorite, 2 parts of butyl stearate, 35 parts of polyester polyol, 20 parts of urotropine with the concentration of 10-60%, 10 parts of glass fiber, 8 parts of potassium perchlorate and 8 parts of ethyl hexyl acrylate; wherein the raw sand is obtained by uniformly mixing quartz sand, chromite sand, magnesia and zircon sand according to the mass ratio of 7:6:7: 8.
The preparation method of the precoated sand in the embodiment adopts the following steps:
(1) preparing raw sand: respectively cleaning quartz sand, chromite sand, magnesia sand and zircon sand with clear water, soaking the cleaned quartz sand, chromite sand, magnesia sand and zircon sand in an acid solution with the concentration of 7mol/L for 2 hours, taking out the cleaned quartz sand, chromite sand, magnesia sand and zircon sand, drying the cleaned quartz sand in a dryer at the drying temperature of 180 ℃, then putting the dried quartz sand, chromite sand, magnesia sand and zircon sand into a high-temperature furnace for firing, cooling the quartz sand, chromite sand, magnesia sand and zircon sand to the room temperature after firing, taking out the quartz sand, chromite sand, magnesia sand and zircon sand, respectively adding the above materials into a ball mill, grinding the mixture into particles with the particle size of 200 meshes and 300 meshes, and finally uniformly mixing the quartz sand;
(2) modifying raw sand: adding 120 parts of raw sand obtained in the step (1), 5 parts of hexamethylene diisocyanate, 3 parts of stearyl alcohol, 3 parts of sodium hypochlorite and 2 parts of butyl stearate into a mixer, stirring at a high speed of 320rpm for 28min, adjusting the mixer to stir at a low speed for 2h when the temperature of materials in the mixer reaches 120 ℃, adding 35 parts of polyester polyol at a low stirring speed of 200rpm, and starting high-speed stirring for 2min after complete addition to obtain modified raw sand;
(3) preparing precoated sand: when the temperature of the modified raw sand in the mixer in the step (2) is reduced to 120 ℃, adding 20 parts of urotropine with the concentration of 10-60%, 10 parts of glass fiber, 8 parts of potassium perchlorate and 8 parts of ethyl hexyl acrylate into the mixer, stirring at high speed for 20min, and taking out after the materials are cooled;
(4) crushing and packaging: and (4) adding the material obtained in the step (3) into a crusher to be crushed into particles with the particle size of 200-300 meshes, cooling to room temperature, taking out and packaging to obtain the high-strength precoated sand.
Comparative example 1
The high-strength precoated sand for 3D printing is prepared from the following raw materials in parts by weight: 100 parts of quartz sand, 30 parts of phenolic resin, 20 parts of urotropine with the concentration of 10-60%, 8 parts of potassium chromate and 6 parts of methyl methacrylate resin.
The preparation method of the precoated sand in the comparative example adopts the following steps:
(1) preparing raw sand: cleaning quartz sand with clean water, soaking the cleaned quartz sand in 1mol/L acid solution for 5 hours, taking out the quartz sand, putting the quartz sand into a dryer for drying, wherein the drying temperature is 100 ℃, the drying is carried out, then putting the quartz sand into a high-temperature furnace for burning, the temperature of the high-temperature furnace is 900 ℃, the burning time is 20 hours, cooling the quartz sand to room temperature after burning, taking out the quartz sand, adding the quartz sand into a ball mill, and grinding the quartz sand into particles with the particle size of 200-mesh and 300-mesh;
(2) preparing precoated sand: when raw sand is added into a mixer to be stirred, the stirring speed is 200rpm, the temperature is kept at 120 ℃, 20 parts of urotropine with the concentration of 10-60 percent, 8 parts of potassium chromate and 6 parts of methyl methacrylate resin are added into the mixer to be stirred at high speed for 20min, the high-speed stirring speed is 320rpm, and the materials are taken out after being cooled;
(3) crushing and packaging: and (3) adding the material obtained in the step (2) into a crusher to be crushed into particles with the particle size of 200-300 meshes, cooling to room temperature, taking out and packaging to obtain the precoated sand.
Comparative example 2
The high-strength precoated sand for 3D printing is prepared from the following raw materials in parts by weight: 100 parts of quartz sand, 30 parts of phenolic resin, 20 parts of urotropine with the concentration of 10-60%, 8 parts of manganese dioxide and 6 parts of vinyl acetate resin.
The preparation method of the precoated sand in the comparative example adopts the following steps:
(1) preparing raw sand: cleaning quartz sand with clean water, soaking the cleaned quartz sand in 1mol/L acid solution for 5 hours, taking out the quartz sand, putting the quartz sand into a dryer for drying, wherein the drying temperature is 100 ℃, the drying is carried out, then putting the quartz sand into a high-temperature furnace for burning, the temperature of the high-temperature furnace is 900 ℃, the burning time is 20 hours, cooling the quartz sand to room temperature after burning, taking out the quartz sand, adding the quartz sand into a ball mill, and grinding the quartz sand into particles with the particle size of 200-mesh and 300-mesh;
(2) preparing precoated sand: adding raw sand into a mixer, stirring at a stirring speed of 250rpm, keeping the temperature at 120 ℃, adding 20 parts of urotropine with the concentration of 10-60%, 8 parts of manganese dioxide and 6 parts of vinyl acetate resin into the mixer, stirring at a high speed of 360rpm for 20min, and taking out after the materials are cooled;
(3) crushing and packaging: and (3) adding the material obtained in the step (2) into a crusher to be crushed into particles with the particle size of 200-300 meshes, cooling to room temperature, taking out and packaging to obtain the precoated sand.
The precoated sand obtained in examples 1 to 4 and comparative examples 1 to 2 were subjected to a performance test in which the precoated sand obtained in each of the examples and comparative examples was prepared into a cast and subjected to a strength test, and the test results are shown in table 1.
TABLE 1 precoated sand test results
As can be seen from Table 1, the casting film prepared from the high-strength precoated sand for 3D printing prepared in the embodiments 1 to 4 of the invention has the normal-temperature tensile strength of 5 to 7.5MPa, the bending strength of 3 to 4MPa, and the flowability of the precoated sand of 4.5 to 7.5 cm/min; the casting film prepared by the precoated sand prepared in the comparative examples 1-2 has the normal-temperature tensile strength of 3.5-3.8MPa, the bending strength of 2-2.4MPa and the flowability of the precoated sand of 1-1.2 cm/min. Compared with a casting film member made of precoated sand in a comparative example, the normal-temperature tensile strength, the bending strength and the fluidity of the high-strength precoated sand for 3D printing are greatly improved, which shows that raw sand is added with a binder, a lubricant and other raw materials in the modification process, so that the resin and the raw sand are connected in a key connection mode, the binding power is stronger, and the precoated sand made by the method has better strength and good fluidity. When printing the molding sand with this tectorial membrane sand as 3D, improved the quality that 3D printed the molding sand, the product intensity of printing is good, the precision is high, also makes the various 3D of adaptation that the molding sand can be fine print the needs of product, has enlarged the application scope of molding sand.
The present invention has been further described with reference to specific embodiments, but it should be understood that the detailed description should not be construed as limiting the spirit and scope of the present invention, and various modifications made to the above-described embodiments by those of ordinary skill in the art after reading this specification are within the scope of the present invention.