Artificial snow and preparation method thereof

Abstract

The present invention provides artificial snow and a method for producing the same. The artificial snow has a multi-layer core-shell structure, comprising, from the inside out, a core, a magnetic layer, a coloring layer, and a protective layer. The core is a spherical hollow powder with a particle size of 50-250 μm, an open-pore structure on the surface, and a single large cavity inside. By using this spherical hollow powder with a single large cavity inside and an open-pore structure on the surface as the core, the present invention achieves artificial snow that is low in cost, lightweight, high in strength, has strong inter-layer bonding, and is highly safe to use. The artificial snow provided by the present invention will significantly promote ice and snow sports and have broad economic and social benefits.

Description

Technical Field

[0001] The present invention relates to the field of materials, and in particular to artificial snow and a preparation method thereof. Background Art

[0002] As a major part of winter sports, skiing has gradually become popular among the public. However, since natural snow only exists in winter and the length of the snow season varies from region to region, the widespread development of skiing has been greatly restricted.

[0003] Currently, two types of artificial snowmaking technologies are used: freezing water to form snow, and creating various organic or inorganic materials that resemble natural snow. The first method is expensive to produce and maintain, and, like natural snow, is subject to seasonal and regional restrictions. The artificial snow created by the second method only resembles natural snow in appearance, but lacks its properties and cannot be used in actual ski resorts.

[0004] Generally speaking, artificial snow that can meet practical application requirements needs to have the three major properties of natural snow: self-aggregation, damping dispersion, and lubricity. Studies have found that magnetized spherical strontium ferrite has good self-aggregation, damping dispersion, and lubricity, making it a potential good material for artificial snow. However, the density of strontium ferrite is relatively high, at 5g / cm 3 As mentioned above, during skiing, the kinetic energy generated by impact is high, causing damage to skiers due to collisions. Using pure strontium ferrite as the core material results in high material consumption and high ski resort construction costs. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention provides artificial snow and a method for preparing the same.

[0006] In a first aspect, the present invention provides artificial snow having a multi-core-shell structure, which comprises, from the inside to the outside, a core, a magnetic layer, a coloring layer, and a protective layer;

[0007] The core is a spherical hollow powder, the particle size of the spherical hollow powder is 50-250 μm, the surface has an open-pore structure, and the interior has a single large cavity.

[0008] Preferably, the spherical hollow powders with a particle size of 100-150 μm account for 55-70% of the spherical hollow powders.

[0009] The artificial snow of the present invention is based on a spherical hollow powder with a single large cavity inside and an open-pore structure on the surface. Compared to other powder materials, this spherical hollow powder is lighter and, compared to other lighter organic materials, has a higher bonding strength with the magnetic layer. In short, the artificial snow of the present invention, designed with this structure, maintains sufficient strength for skiing while simultaneously reducing its overall density. This reduces the kinetic energy generated by impacts, minimizes the chance of breakage from collisions, and reduces the potential risk of injury to skiers. Furthermore, the structural design of the artificial snow of the present invention reduces the use of relatively expensive strontium ferrite, thereby lowering the production cost of artificial snow.

[0010] In some specific embodiments of the present invention, the average diameter of the surface pores of the spherical hollow powder is 0.1-5 μm, and the surface open porosity is 20-40%.

[0011] In some specific embodiments of the present invention, the average shell thickness of the spherical hollow powder is 5-15 μm.

[0012] In some specific embodiments of the present invention, the bulk density of the spherical hollow powder is 0.35-0.5 g / cm 3 , the porosity is 60-70%.

[0013] In some specific embodiments of the present invention, the raw materials for the spherical hollow powder are composed of: 40-50% by mass of alumina, 20-30% by mass of fly ash, 10-30% by mass of tailings, 5-10% by mass of coal gangue, 5-10% by mass of silicon dioxide, and 3-8% by mass of borax. To improve the bonding strength and magnetizing properties of the hollow powder and ferrite, alumina and fly ash are selected as the primary raw materials, and a trace reaction occurs during the bonding to increase the chemical bonding strength and the magnetic content of iron, silicon, and aluminum. Tailings are used as a secondary main material. The tailings contain lanthanum, which undergoes a doping reaction at high temperatures to further increase the chemical bonding strength. Coal gangue and silicon dioxide are used as auxiliary materials to adjust the aluminum-silicon ratio. Borax is also added to adjust the sintering temperature and reduce energy consumption.

[0014] In some embodiments of the present invention, the diameter of the core is 1-6 mm.

[0015] In some specific embodiments of the present invention, the magnetic layer is strontium ferrite or a mixture of strontium ferrite and the spherical hollow powder, and has a thickness of 3-5 mm.

[0016] In some specific embodiments of the present invention, the colored layer is a ceramic material or a glass glaze, and has a thickness of 0.1-2 mm.

[0017] The material used for the coloring layer is designed to give the artificial snow a color similar to natural snow, or a specific color. Typically, white inorganic ceramic powders are used, including one or more of titanium dioxide, feldspar, silica, talc, aluminum oxide, zinc oxide, zirconium oxide, and calcium carbonate.

[0018] It should be noted that, during the preparation and molding process of the magnetic layer and the coloring layer of the present invention, some auxiliary agents, such as a binder, may be added as needed.

[0019] In some embodiments of the present invention, the protective layer is made of a thermoplastic resin or a thermosetting resin and has a thickness of 0.1-1 mm. Specifically, the protective layer material may be one or more of polyurethane adhesive, nitrile adhesive, epoxy resin, phenolic adhesive, silicone rubber, and the like. The weight of the protective layer accounts for 3-7% of the weight of the artificial snow particles.

[0020] As previously mentioned, the artificial snow of this invention utilizes spherical hollow powder, resulting in a low density. This reduces the kinetic energy generated by impact during skiing, effectively reducing the chance of breakage from collision. Furthermore, the protective layer designed in this invention further prevents breakage from particle collision during skiing, reducing the potential risk of injury to skiers.

[0021] In some specific embodiments of the present invention, the saturation magnetization of the magnetic layer of the artificial snow at room temperature is greater than 55emu / g, and the coercive force is greater than 2400Oe.

[0022] The magnetic properties between artificial snow particles must meet the requirements of self-agglomeration, damping dispersion and lubricity, which can be adjusted by the proportion of strontium ferrite or the final magnetization intensity.

[0023] In a second aspect, the present invention also provides a method for preparing the above-mentioned artificial snow.

[0024] The preparation method provided by the present invention comprises:

[0025] The spherical hollow powder is mixed with the binder 1 and granulated to obtain a core;

[0026] Strontium ferrite or a mixture of strontium ferrite and spherical hollow powder and a binder 2 are added to a granulator to form a magnetic layer wrapped around the core;

[0027] Wrapping the magnetic layer with a colored layer to obtain a semi-finished product and sintering it; the sintering temperature is preferably 1150-1250°C;

[0028] After sintering, a protective layer is formed on the surface of the semi-finished product to obtain artificial snow.

[0029] The preparation method provided by the invention has a simple production process, can be produced on a large scale, and has a positive effect on the promotion of ice and snow sports.

[0030] The binder 1 is a water-soluble binder, which may be one or more of starch, polyvinyl alcohol, hydroxymethyl cellulose, and the like.

[0031] The adhesive 2 is one or more of epoxy resin, phenolic resin, urea-formaldehyde resin and the like.

[0032] In some embodiments of the present invention, the material for the coloring layer is prepared into a solution, which is then applied to the magnetic layer via high-pressure spraying to form a colored layer. After drying, a semi-finished product is obtained. In addition to the ceramic material or glass glaze, the coloring layer also requires the addition of an appropriate amount of binder 2, depending on the actual situation.

[0033] In some embodiments of the present invention, a protective layer is formed on the surface of the semi-finished product by high-pressure spraying.

[0034] In some embodiments of the present invention, the method for preparing the spherical hollow powder comprises:

[0035] S1: Prepare a slurry of powder raw materials and water, and grind the powder to a particle size of 0.5μm-2μm;

[0036] Furthermore, the mass fraction of the powder raw material in the slurry is about 15-55%.

[0037] Preferably, the grinding is carried out in a grinder for 24-48 hours, and the rotation speed of the grinder is 500-2000 rpm.

[0038] The grinding rate and time of the slurry affect the particle size of the powder in the slurry. The smaller the particle size, the smaller the charge resistance, and the easier it is to aggregate on the foam surface, affecting the wall thickness of the final spherical hollow powder. High-speed ball milling can greatly increase the surface energy of inorganic powder particles in the process of becoming smaller, thereby affecting the rheological properties of the slurry.

[0039] S2: adding a binder and / or a surfactant to the slurry in step S1 and stirring to form a foam slurry;

[0040] Furthermore, since the amount of binder added and the grinding process jointly affect the rheological properties of the slurry, the mass fraction of the binder added is 0.1-4%.

[0041] Furthermore, since the amount of surfactant added, the stirring time and the stirring rate affect the diameter of the foam, the mass fraction of the surfactant added is 0.1-1.5%; the stirring time is 20-60 minutes, and the stirring rate is 800-1500 rpm.

[0042] Furthermore, the foam diameter in the foam slurry is 0.01-0.2 mm.

[0043] S3: subjecting the foam slurry in step S2 to an aging reaction in a closed reactor;

[0044] Furthermore, the temperature of the closed reactor is 5-45°C.

[0045] Preferably, the aging reaction time is 2-24 hours.

[0046] Preferably, the aging reaction is carried out under stirring; more preferably, the stirring rate is 100-200 rpm.

[0047] By controlling the above reaction conditions, the merging and growth of small bubbles and large bubbles can be achieved, thereby achieving the generation of large internal cavities. This process, combined with the rheological properties of the slurry in steps S1 and S2, determines whether there are pores and the number of pores in the final spherical hollow powder with thick walls.

[0048] S4: atomizing and molding the product obtained in step S3 in a molding tower to obtain a spherical hollow powder body;

[0049] Furthermore, the forming tower is provided with an atomizing disk, and the rotation speed of the atomizing disk is 8000-15000 rpm. The rotation speed of the atomizing disk is combined with the rheological properties of the slurry in steps S1 and S2 to jointly affect the particle size of the final powder.

[0050] Furthermore, the inlet temperature of the forming tower is 300-450° C., and the outlet temperature of the forming tower is not less than 120° C. The inlet and outlet temperatures of the forming tower affect the moisture content and drying efficiency of the spherical hollow powder body.

[0051] Furthermore, by controlling the inlet and outlet temperatures of the forming tower, the particle size of the spherical hollow powder body is controlled to be 1-200 μm, and the moisture content is controlled to be 0.1-0.5%.

[0052] S5: sintering the spherical hollow powder body obtained in step S4, and obtaining the spherical hollow powder body after cooling.

[0053] Preferably, the sintering is carried out in a muffle furnace. More preferably, the spherical hollow powder body is placed in a sagger and then placed in the muffle furnace for sintering.

[0054] Furthermore, the sintering temperature is 900-1600° C., and the sintering holding time is 0.5-2 h.

[0055] The present invention provides artificial snow and a method for producing it. By using a spherical hollow powder with a single large cavity inside and an open-pore structure on the surface as a core, the resulting artificial snow is low-cost, lightweight, high-strength, with strong inter-layer bonding and high safety. The artificial snow provided by the present invention will significantly promote ice and snow sports and have broad economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 A schematic diagram of the structure of artificial snow provided by an embodiment of the present invention;

[0057] Figure 2 This is a scanning electron microscope image of the spherical hollow powder used in the examples of the present invention. DETAILED DESCRIPTION

[0058] Explanation of terms:

[0059] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variations thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0060] The conjunction "consisting of" excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed, excluding materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim, rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0061] When amount, concentration or other value or parameter are represented with range, preferred range or the range that a series of upper preferred value and lower preferred value limit are expressed, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value and any range lower limit or preferred value, and no matter whether this scope is disclosed separately.For example, when disclosing scope " 1-5 ", described scope should be interpreted as including scope " 1-4 ", " 1-3 ", " 1-2 ", " 1-2 and 4-5 ", " 1-3 and 5 " etc.When numerical range is described in this article, unless otherwise stated, otherwise this scope is intended to include its end value and all integers and fractions within this range.

[0062] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0063] Unless otherwise specified, the technical means used in the examples of the present invention are conventional means well known to those skilled in the art. Unless otherwise specified, the materials and reagents used in the examples of the present invention can be obtained through regular commercial channels.

[0064] In the following examples, magnetization is a physical quantity that describes the strength of a macroscopic magnetic body. Coercivity is a physical quantity that measures a magnet's resistance to demagnetization and represents the coercive force required for the magnetization M in a material to return to zero. Both magnetization and coercivity can be measured using a vibrating sample magnetometer (VSM), which was produced by Quantum Design in this example.

[0065] Example 1

[0066] This embodiment provides an artificial snow with a multiple core-shell structure, such as Figure 1 As shown, from the inside to the outside, they are the core, magnetic layer, coloring layer and protective layer;

[0067] The core has a diameter of 5.5 mm and is made of spherical hollow powder. The particle size of the spherical hollow powder is 200-250 μm, the surface has an open-pore structure, the average diameter of the surface pores is 4.6 μm, the surface open porosity is 40%, and there is a single large cavity inside. The average shell thickness of the spherical hollow powder is 5-7 μm, and the bulk density of the spherical hollow powder is 0.38 g / cm 3 , the porosity is 70%.

[0068] The raw material composition of the spherical hollow powder is: 40% by mass of aluminum oxide, 20% by mass of fly ash, 15% by mass of tailings, 10% by mass of coal gangue, 8% by mass of silicon dioxide and 7% by mass of borax.

[0069] The magnetic layer is a mixture of strontium ferrite and spherical hollow powder in a mass ratio of 7:3, and has a thickness of 3 mm.

[0070] The coloring layer is white ceramic glaze with a thickness of 0.4mm.

[0071] The protective layer is transparent rubber resin with a thickness of 1mm.

[0072] This embodiment also provides a method for preparing the artificial snow, and the specific steps are as follows:

[0073] Spherical hollow powder is added to a mixing and granulating machine and sprayed with a 5% aqueous solution of PVA. After granulation, a core layer with a thickness of 5.5 mm is obtained. Strontium ferrite and spherical hollow powder are mixed in a mixer at a mass ratio of 7:3 and set aside. The mixture and epoxy resin are added to the mixing and granulating machine in small portions according to the proportions. A 3 mm thick magnetic layer is formed around the core layer. Excess powder is removed by vibrating and sieving. A solution of white ceramic glaze is prepared and high-pressure sprayed to form a 0.4 mm thick colored layer around the magnetic layer. After drying, the semi-finished spheres are sintered at 1200°C. After sintering, a transparent rubber resin protective layer is applied by high-pressure spraying. After drying and solidification, the artificial snow is obtained.

[0074] The preparation steps of spherical hollow powder are as follows:

[0075] S1: The powder raw material and water are mixed into a slurry at a ratio of 1:1. The slurry is ground in a grinder at a speed of 800 rpm for 24 hours until the powder particle size is between 1.2 μm and 1.5 μm.

[0076] S2: Add 3% by mass of CMC and 1% by mass of animal protein to the ground slurry, and stir at high speed for 60 minutes at a stirring rate of 800 rpm to form a foam slurry with a foam diameter of 0.05 mm.

[0077] S3: The foam slurry was transferred to a closed reactor and subjected to aging reaction at 5° C. for 15 h. The reaction was carried out under stirring at a stirring rate of 180 rpm.

[0078] S4: The product obtained in step S3 is transported into a forming tower using a diaphragm pump to form a foam slurry. The inlet temperature of the forming tower is 300°C, and the outlet temperature of the forming tower is 150°C. The forming tower is provided with an atomizing disk, and the rotation speed of the atomizing disk is 12000 rpm to obtain a spherical hollow powder body.

[0079] S5: The spherical hollow powder body obtained in step S4 is placed in a sagger and sintered in a muffle furnace at a sintering temperature of 1200°C for 2 hours, and then cooled to room temperature to obtain the spherical hollow powder body. Figure 2 shown.

[0080] After testing, the density of the artificial snow obtained in this embodiment is 3.1g / cm 3The artificial snow was manufactured using a magnetic coating and sprayed with a coloring layer. The surface showed no visible pores or peeling, and the coloring layer remained intact after sintering. The tested compressive strength was 273 MPa, indicating high strength. The material also fractured rather than detached between layers, demonstrating strong interlayer bonding.

[0081] Example 2

[0082] This embodiment provides an artificial snow having a multi-core-shell structure, which comprises a core, a magnetic layer, a coloring layer, and a protective layer from the inside to the outside.

[0083] The core has a diameter of 2 mm and is made of spherical hollow powder. The particle size of the spherical hollow powder is 50-150 μm, the surface has an open-pore structure, the average diameter of the surface pores is 0.2 μm, the surface open porosity is 20%, and there is a single large cavity inside. The average shell thickness of the spherical hollow powder is 12-15 μm, and the bulk density of the spherical hollow powder is 0.5 g / cm 3 , the porosity is 60%.

[0084] The raw material composition of the spherical hollow powder is: 50% by mass of aluminum oxide, 20% by mass of fly ash, 10% by mass of tailings, 10% by mass of coal gangue, 5% by mass of silicon dioxide and 5% by mass of borax.

[0085] The magnetic layer is a mixture of strontium ferrite and spherical hollow powder in a mass ratio of 7:3, and has a thickness of 4.5 mm.

[0086] The coloring layer is white ceramic glaze with a thickness of 0.3mm.

[0087] The protective layer is transparent rubber resin with a thickness of 0.1mm.

[0088] This embodiment also provides a method for preparing the artificial snow, and the specific steps are as follows:

[0089] Spherical hollow powder is added to a mixing and granulating machine and sprayed with a 5% aqueous solution of PVA. After granulation, a core layer with a thickness of 2mm is obtained. Strontium ferrite and spherical hollow powder are mixed in a mixer at a mass ratio of 7:3 and set aside. The mixture and epoxy resin are added to the mixing and granulating machine in small portions according to the proportions. A 4.5mm thick magnetic layer is formed around the core layer. Excess powder is removed by vibrating and sieving. A solution of white ceramic glaze is prepared and high-pressure sprayed to form a 0.3mm thick colored layer around the magnetic layer. After drying, the semi-finished spheres are sintered at 1150°C. After sintering, a transparent rubber resin protective layer is applied by high-pressure spraying. After drying and solidification, the artificial snow is obtained.

[0090] The preparation steps of spherical hollow powder are as follows:

[0091] S1: The powder raw material and water are mixed into a slurry at a ratio of 1:1. The slurry is ground in a grinder at a speed of 800 rpm for 24 hours until the powder particle size is between 0.5-0.9 μm.

[0092] S2: Add 3% by mass of CMC and 1% by mass of animal protein to the ground slurry, and stir at high speed for 60 minutes at a stirring rate of 1400 rpm to form a foam slurry with a foam diameter of 0.02 mm.

[0093] S3: The foam slurry was transferred to a closed reactor and subjected to aging reaction at 5° C. for 20 h. The reaction was carried out under stirring at a stirring rate of 200 rpm.

[0094] S4: The product obtained in step S3 is transported into a forming tower using a diaphragm pump to form a foam slurry. The inlet temperature of the forming tower is 300°C, and the outlet temperature of the forming tower is 150°C. The forming tower is provided with an atomizing disk, and the rotation speed of the atomizing disk is 12000 rpm to obtain a spherical hollow powder body.

[0095] S5: The spherical hollow powder body obtained in step S4 is placed into a sagger and placed in a muffle furnace for sintering at a sintering temperature of 1200° C. for 2 hours, and then cooled to room temperature to obtain the spherical hollow powder.

[0096] After testing, the density of the artificial snow obtained in this embodiment is 3.7g / cm 3 , compressive strength is 376MPa, magnetization intensity>75emu / g, and coercive force>3300Oe.

[0097] Example 3

[0098] This embodiment provides an artificial snow with a multiple core-shell structure, such as Figure 1 As shown, from the inside to the outside, they are the core, magnetic layer, coloring layer and protective layer;

[0099] The core has a diameter of 3.5 mm and is made of spherical hollow powder. The particle size of the spherical hollow powder is 100-200 μm, the surface has an open-pore structure, the average diameter of the surface pores is 2 μm, the surface open porosity is 30%, and there is a single large cavity inside. The average shell thickness of the spherical hollow powder is 9-11 μm, and the bulk density of the spherical hollow powder is 0.43 g / cm 3 , the porosity is 65%.

[0100] The raw material composition of the spherical hollow powder is: 40% by mass of aluminum oxide, 20% by mass of fly ash, 15% by mass of tailings, 10% by mass of coal gangue, 8% by mass of silicon dioxide and 7% by mass of borax.

[0101] The magnetic layer is a mixture of strontium ferrite and spherical hollow powder in a mass ratio of 7:3, and has a thickness of 4 mm.

[0102] The coloring layer is white ceramic glaze with a thickness of 0.4mm.

[0103] The protective layer is transparent rubber resin with a thickness of 0.5mm.

[0104] This embodiment also provides a method for preparing the artificial snow, and the specific steps are as follows:

[0105] Spherical hollow powder is added to a mixing and granulating machine and sprayed with a 5% aqueous solution of PVA. After granulation, a core layer with a thickness of 3.5mm is obtained. Strontium ferrite powder and spherical hollow powder are mixed in a mixer at a mass ratio of 7:3 and set aside. The mixture and epoxy resin are added to the mixing and granulating machine in small portions according to the proportions. A 4mm thick magnetic layer is formed around the core layer. Excess powder is removed by vibrating and sieving. A solution of white ceramic glaze is prepared and high-pressure sprayed to form a 0.4mm thick colored layer around the magnetic layer. After drying, the semi-finished spheres are sintered at 1200°C. After sintering, a transparent rubber resin protective layer is applied by high-pressure spraying. After drying and solidification, the artificial snow is obtained.

[0106] The preparation steps of spherical hollow powder are as follows:

[0107] S1: The powder raw material and water are mixed into a slurry at a ratio of 1:1. The slurry is ground in a grinder at a speed of 800 rpm for 24 hours until the powder particle size is between 0.7 μm and 1.2 μm.

[0108] S2: Add 3% by mass of CMC and 1% by mass of animal protein to the ground slurry, and stir at high speed for 60 minutes at a stirring rate of 1200 rpm to form a foam slurry with a foam diameter of 0.03 mm.

[0109] S3: The foam slurry was transferred to a closed reactor and subjected to aging reaction at 5° C. for 13 h. The reaction was carried out under stirring at a stirring rate of 150 rpm.

[0110] S4: The product obtained in step S3 is transported into a forming tower using a diaphragm pump to form a foam slurry. The inlet temperature of the forming tower is 300°C, and the outlet temperature of the forming tower is 150°C. The forming tower is provided with an atomizing disk, and the rotation speed of the atomizing disk is 12000 rpm to obtain a spherical hollow powder body.

[0111] S5: The spherical hollow powder body obtained in step S4 is placed into a sagger and placed in a muffle furnace for sintering at a sintering temperature of 1200° C. for 2 hours, and then cooled to room temperature to obtain the spherical hollow powder.

[0112] After testing, the density of the artificial snow obtained in this embodiment is 3.4g / cm 3 , compressive strength is 307MPa, magnetization intensity>65emu / g, and coercive force>3200Oe.

[0113] Comparative Example 1

[0114] This comparative example provides artificial snow, which comprises, from the inside out, a magnetic core layer, a coloring layer, and a protective layer. The magnetic layer is made of strontium ferrite and has a thickness (diameter) of 9 mm; the coloring layer is made of white ceramic glaze and has a thickness of 0.4 mm; and the protective layer is made of transparent rubber resin and has a thickness of 1 mm.

[0115] Strontium ferrite powder is added to a mixing and granulating machine and sprayed with a 5% PVA aqueous solution. After granulation, a magnetic core layer with a thickness of 9mm is obtained. A white ceramic glaze is prepared into a solution and sprayed with high pressure to form a 0.4mm thick colored layer around the magnetic layer. After drying, the semi-finished ball is sintered at 1150°C. After sintering, the surface of the ball is sprayed with high pressure to form a transparent rubber resin protective layer. After drying and solidification, the artificial snow is obtained.

[0116] After testing, the density of the artificial snow obtained in this comparative example is 5.1g / cm 3 , compressive strength is 352MPa, magnetization intensity>63emu / g, and coercive force>3180Oe.

[0117] Comparative Example 2

[0118] This comparative example provides an artificial snow having a multiple core-shell structure, which comprises a core, a magnetic layer, a coloring layer and a protective layer from the inside to the outside;

[0119] The core has a diameter of 5.5 mm and is made of EPS foam balls. The diameter of the EPS foam balls is 5.5 mm and the bulk density is 0.04 g / cm 3 The magnetic layer is strontium ferrite, 3mm thick. The coloring layer is white ceramic glaze, 0.4mm thick. The protective layer is transparent rubber resin, 1mm thick.

[0120] This comparative example also provides a method for preparing the artificial snow, and the specific steps are as follows:

[0121] A 5.5mm EPS foam ball is sprayed with a 5% PVA aqueous solution. Strontium ferrite powder is then sprinkled on the surface to coat the ball. The coated ball is then placed in a mixing and granulating machine. Strontium ferrite powder and epoxy resin are then added to the machine in small, proportional increments to form a 3mm thick magnetic layer. A 0.4mm thick colored layer is then formed over the magnetic layer. After drying, the semi-finished ball is sintered at 1150°C. After sintering, a 1mm thick transparent rubber resin protective layer is formed on the surface of the ball using high-pressure spraying. After drying and curing, the artificial snow is obtained.

[0122] After testing, the density of the artificial snow obtained in this comparative example is 1.9g / cm 3 , compressive strength is 127MPa, magnetization intensity>48emu / g, coercive force>2100Oe. The density of this artificial snow is only 1.9g / cm 3 However, the strength is greatly reduced, and the magnetization intensity and coercive force are also reduced, which cannot meet the requirements for safe use as artificial snow.

[0123] Comparative Example 3

[0124] This comparative example provides artificial snow having a multiple core-shell structure, which comprises, from the inside to the outside, a core, a magnetic layer, a coloring layer, and a protective layer. The core has a diameter of 5.5 mm and is made of spherical hollow powder. The spherical hollow powder has a particle size of 300 μm, an open-pore structure on the surface, an average diameter of the surface pores of 4.2 μm, and a surface open porosity of 50%. The interior has a porous interconnected structure with a porosity of 80% and a bulk density of 0.36 g / cm. 3 .

[0125] The raw material composition of the spherical hollow powder is: 40% by mass of aluminum oxide, 20% by mass of fly ash, 15% by mass of tailings, 10% by mass of coal gangue, 8% by mass of silicon dioxide and 7% by mass of borax.

[0126] The magnetic layer is a mixture of strontium ferrite and spherical hollow powder in a mass ratio of 7:3, and has a thickness of 3 mm.

[0127] The coloring layer is white ceramic glaze with a thickness of 0.4mm.

[0128] The protective layer is transparent rubber resin with a thickness of 1mm.

[0129] This comparative example also provides a method for preparing the artificial snow, and the specific steps are as follows:

[0130] Spherical hollow powder is added to a mixing and granulating machine and sprayed with a 5% aqueous solution of PVA. After granulation, a core layer with a thickness of 5.5 mm is obtained. Strontium ferrite and spherical hollow powder are mixed in a mixer at a mass ratio of 7:3 and set aside. The mixture and epoxy resin are added to the mixing and granulating machine in small portions according to the proportions. A 3 mm thick magnetic layer is formed around the core layer. Excess powder is removed by vibrating and sieving. A solution of white ceramic glaze is prepared and high-pressure sprayed to form a 0.4 mm thick colored layer around the magnetic layer. After drying, the semi-finished spheres are sintered at 1200°C. After sintering, a transparent rubber resin protective layer is applied by high-pressure spraying. After drying and solidification, the artificial snow is obtained.

[0131] The preparation steps of spherical hollow powder are as follows:

[0132] S1: The powder raw material and water are prepared into a slurry in a mass ratio of 1:1. The slurry is ground in a grinder at a speed of 800 rpm for 24 hours until the powder particle size is between 3μm and 10μm.

[0133] S2: The ground slurry in step S1 is divided into two parts, slurry A and slurry B, according to a mass ratio of 1:10. 3% CMC by mass and 1.5% SAS by mass are added to the slurry A, and the mixture is stirred at high speed for 20 minutes at a stirring rate of 1000 rpm to form a foam slurry C with a foam diameter of 0.05-0.3 mm; 1.5% CMC by mass and 0.1% SDS by mass are added to the slurry B, and the mixture is stirred at high speed for 60 minutes at a stirring rate of 1500 rpm to form a foam slurry D with a foam diameter of 5-50 μm.

[0134] S3: The foam slurry C and the foam slurry D are mixed and stirred uniformly, with a stirring time of 40 minutes and a stirring rate of 800 rpm.

[0135] S4: The product obtained in step S3 is transported into a forming tower using a diaphragm pump to form a foam slurry. The inlet temperature of the forming tower is 370°C, and the outlet temperature of the forming tower is 90°C. The forming tower is provided with an atomizing disk, and the rotation speed of the atomizing disk is 8000 rpm to obtain a spherical hollow powder body.

[0136] S5: The spherical hollow powder body obtained in step S4 is placed into a sagger and placed in a muffle furnace for sintering at a sintering temperature of 1100° C. for 2 hours, and then cooled to room temperature to obtain the spherical hollow powder.

[0137] After testing, the density of the artificial snow obtained in this comparative example is 3.0g / cm 3The compressive strength is 157 MPa, the magnetization is >51 emu / g, and the coercivity is >2200 Oe. Although the density of this artificial snow has been reduced, its strength has also been significantly reduced, and its magnetization and coercivity have also been reduced, making it unsafe for use as artificial snow.

[0138] It can be seen from the above results that the artificial snow prepared by the present invention has the advantages of low cost, light weight, high strength, strong bonding between layers, and high safety in use. It is suitable for large-scale production and is beneficial to promoting the development of ice and snow sports.

[0139] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An artificial snow, characterized in that: It has a multiple core-shell structure, which consists of a core, a magnetic layer, a coloring layer and a protective layer from the inside to the outside. The core is a spherical hollow powder with a particle size of 50-250 μm, an open-pore structure on the surface, and a single large cavity inside. The average diameter of the pores on the surface of the spherical hollow powder is 0.1-5 μm, and the surface porosity is 20-40%; The bulk density of the spherical hollow powder is 0.35-0.5 g / cm 3 , porosity is 60-70%; The raw material composition of the spherical hollow powder is: 40-50% by mass of aluminum oxide, 20-30% by mass of fly ash, 10-30% by mass of tailings, 5-10% by mass of coal gangue, 5-10% by mass of silicon dioxide and 3-8% by mass of borax, and the sum of the mass fractions of the above raw material compositions is 100%.

2. The artificial snow according to claim 1, characterized in that The average shell thickness of the spherical hollow powder is 5-15 μm.

3. The artificial snow according to claim 2, characterized in that The core has a diameter size of 1-6 mm.

4. The artificial snow according to claim 3, characterized in that The magnetic layer is strontium ferrite or a mixture of strontium ferrite and the spherical hollow powder, and has a thickness of 3-5 mm.

5. The artificial snow according to claim 4, characterized in that The coloring layer is made of ceramic material or glass glaze and has a thickness of 0.1-2 mm; And / or, the protective layer is made of thermoplastic resin or thermosetting resin and has a thickness of 0.1-1 mm.

6. The artificial snow according to any one of claims 1 to 5, characterized in that: The magnetic layer of the artificial snow has a saturation magnetization intensity of >55emu / g and a coercive force of >2400 Oe at room temperature.

7. The method for making artificial snow according to any one of claims 1 to 6, characterized in that: include: The spherical hollow powder is mixed with the binder 1 and granulated to obtain a core; Strontium ferrite or a mixture of strontium ferrite and spherical hollow powder and a binder 2 are added to a granulator to form a magnetic layer wrapped around the core; Wrapping the magnetic layer with a colored layer to obtain a semi-finished product for sintering; After sintering, a protective layer is formed on the surface of the semi-finished product to obtain artificial snow.

8. The method for making artificial snow according to claim 7, characterized in that: The sintering temperature is 1150-1250°C.

9. The method for making artificial snow according to claim 8, characterized in that: The preparation method of the spherical hollow powder comprises: S1: Prepare a slurry of powder raw materials and water, and grind the powder to a particle size of 0.5μm-2μm; S2: adding a binder and / or a surfactant to the slurry in step S1 and stirring to form a foam slurry; S3: subjecting the foam slurry in step S2 to an aging reaction in a closed reactor; S4: atomizing and molding the product obtained in step S3 in a molding tower to obtain a spherical hollow powder body; S5: sintering the spherical hollow powder body obtained in step S4, and obtaining the spherical hollow powder body after cooling.

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