Modified superfine ultrapure silica powder as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of silica powder preparation, and discloses modified superfine and ultrapure silica powder as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing quartz raw ore with an acid pickling solution, and carrying out acid leaching to obtain silica powder with impurities removed on the surface; mixing the silicon micro-powder with impurities removed on the surface with a chlorinating agent, and carrying out chloridizing roasting to obtain ultrapure silicon micro-powder; mixing and grinding the ultra-pure silica powder and water; mixing and grinding to obtain slurry, and drying to obtain superfine ultra-pure silica powder; and mixing the superfine ultra-pure silica powder with a silane coupling agent, and carrying out modification treatment to obtain the modified superfine ultra-pure silica powder. The modified superfine ultra-pure silica powder is added into the rubber product, so that the tensile strength, tear resistance and aging resistance of the rubber product can be improved, and the modified superfine ultra-pure silica powder has a reinforcing effect. The silica powder is filled in the latex after being treated by the coupling agent, the silica powder is easy to disperse, the vulcanization speed of the rubber material can be improved, and the physical property of the rubber product is enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of silicon micropowder preparation, and in particular to a modified ultrafine ultrapure silicon micropowder and a preparation method and application thereof. Background Art

[0002] Latex gloves are a type of gloves made from latex. Made from natural latex and other fine additives, latex gloves are specially surface treated and comfortable to wear. They are widely used in industrial and agricultural production, medical treatment, and daily life, and are essential hand protection products. Latex gloves are wear-resistant, puncture-resistant, resistant to acids, alkalis, grease, fuel, and a variety of solvents. They have a wide range of chemical resistance and good oil resistance.

[0003] Since latex gloves are thin products, many reinforcing agents cannot be added. In addition, medical latex gloves are restricted to antioxidants, so the products generally have shortcomings such as poor performance, short storage period, easy aging and stickiness. Research shows that the introduction of nano-silicon dioxide into polymer materials can significantly improve the above properties.

[0004] Silica powder is a white powdery inorganic mineral raw material made from natural microcrystalline quartz ore. It has the characteristics of high sphericity, nearly equiaxial particles, fine hand feel, good dispersion and leveling, and low oil absorption. Since there are many bubbles in the quartz sand ore, and the content of elements such as iron, aluminum, magnesium, and calcium is high, the impurity elements are mostly in the form of oxides, feldspar, kaolinite, mica, etc., forming inclusion impurities in the quartz sand, which are difficult to remove, resulting in insufficient purity of silica in silica powder. Excessive impurity content will lead to reduced performance of rubber products, such as tear resistance and abrasion resistance, which greatly reduces its role in rubber gloves. In order to ensure product quality, impurities need to be removed so that the silica content of silica powder reaches more than 99% before it can be added to rubber products as a functional filler. Summary of the invention

[0005] The purpose of the present invention is to provide a modified ultrafine ultrapure silicon micropowder and a preparation method and application thereof, so as to solve the problem that the high impurity content in the silicon micropowder leads to reduced performance of rubber products.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing modified ultrafine ultrapure silicon micropowder, comprising the following steps:

[0008] (1) mixing the quartz ore with the pickling solution and performing acid leaching to obtain silicon micropowder with surface impurities removed;

[0009] (2) mixing the surface-removed silicon micropowder with a chlorinating agent and performing chlorination roasting to obtain ultrapure silicon micropowder;

[0010] (3) mixing and grinding the ultrapure silicon powder with water; drying the slurry obtained by mixing and grinding to obtain ultrafine ultrapure silicon powder;

[0011] (4) The ultrafine ultrapure silicon powder is mixed with a silane coupling agent and subjected to modification treatment to obtain modified ultrafine ultrapure silicon powder.

[0012] Preferably, in the preparation method, in step (1), the pickling solution comprises a mixture of a chelating agent, an organic acid and an inorganic acid solution;

[0013] The chelating agent includes 2,2'-bipyridine and / or 1,10-phenanthroline;

[0014] The organic acid includes glycolic acid and / or citric acid;

[0015] The inorganic acid solution includes one or more of hydrochloric acid solution, sulfuric acid solution, and nitric acid solution;

[0016] The mass ratio of the chelating agent to the organic acid is 1-2:2-4;

[0017] The mass concentration of the chelating agent in the pickling solution is 3-6%;

[0018] The mass concentration of the inorganic acid solution is 15-20%.

[0019] Preferably, in the preparation method, in step (1), the acid leaching temperature is room temperature, and the acid leaching time is 10 to 30 minutes.

[0020] Preferably, in the preparation method, in step (2), the chlorinating agent includes one or more of hydrogen chloride, chlorine, and ammonium chloride;

[0021] The mass ratio of the chlorinating agent to the surface-decontaminated silicon micropowder is 0.05-0.1:1.

[0022] Preferably, in the preparation method, in step (2), the temperature of the chlorination roasting is 600 to 900° C., and the time of the chlorination roasting is 45 to 90 minutes.

[0023] Preferably, in the preparation method, in step (3), the rotation speed of the mixed grinding is 3000-3500 r / min, the time of the mixed grinding is 120-240 min, the mass ratio of the balls in the mixed grinding is 2.2-2.5:1, the grinding balls in the mixed grinding include a mixture of balls with diameters of 1.2-1.4 mm, 1.6-1.8 mm, 2.0-2.2 mm and 2.4-2.6 mm, and the mass ratio of the grinding balls with diameters of 1.2-1.4 mm, the grinding balls with diameters of 1.6-1.8 mm, the grinding balls with diameters of 2.0-2.2 mm and the grinding balls with diameters of 2.4-2.6 mm is 0.5-1:1-2:0.5-1:3-4;

[0024] The mass concentration of the slurry obtained by mixing the ultrapure silicon powder with water is 75-80%.

[0025] Preferably, in the preparation method, in step (4), the silane coupling agent includes one or more of silane coupling agent 4721, KH-550, and KH-171;

[0026] The mass of the silane coupling agent is 0.6-1% of the mass of the ultrafine ultrapure silicon powder.

[0027] Preferably, in the preparation method, in step (4), the temperature of the modification treatment is 75 to 100° C., and the time of the modification treatment is 20 to 40 minutes.

[0028] The invention also provides a modified ultrafine ultrapure silicon powder.

[0029] The invention also provides an application of modified ultrafine ultrapure silicon powder in the preparation of rubber products.

[0030] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0031] The modified ultrafine ultrapure silicon micropowder obtained by the present invention is added to rubber products to improve the tensile strength, tear resistance and aging resistance of the rubber products and has a reinforcing effect. The silicon micropowder is filled in latex after being treated with a coupling agent. The silicon micropowder is easy to disperse and can increase the vulcanization speed of the rubber compound and enhance the physical properties of the rubber products. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments or the prior art are briefly introduced below.

[0033] Figure 1 Schematic diagram of the preparation process of modified ultrafine ultrapure silicon powder. DETAILED DESCRIPTION

[0034] The present invention provides a method for preparing modified ultrafine ultrapure silicon micropowder, comprising the following steps:

[0035] (1) mixing the quartz ore with the pickling solution and performing acid leaching to obtain silicon micropowder with surface impurities removed;

[0036] (2) mixing the surface-removed silicon micropowder with a chlorinating agent and performing chlorination roasting to obtain ultrapure silicon micropowder;

[0037] (3) mixing and grinding the ultrapure silicon powder with water; drying the slurry obtained by mixing and grinding to obtain ultrafine ultrapure silicon powder;

[0038] (4) The ultrafine ultrapure silicon powder is mixed with a silane coupling agent and subjected to modification treatment to obtain modified ultrafine ultrapure silicon powder.

[0039] In the present invention, in step (1), the quartz ore further comprises: crushing and grinding in sequence before acid leaching.

[0040] In the present invention, the conditions for the crushing and the grinding are not limited, and the schemes well known to those skilled in the art can be adopted. Specifically in the embodiment of the present invention, the average particle size of the crushed quartz ore is preferably 20 mm; the particle size of the ground quartz ore is preferably 80 mesh.

[0041] In the present invention, in step (1), the pickling solution preferably comprises a mixture of a chelating agent, an organic acid and an inorganic acid solution.

[0042] In the present invention, the chelating agent preferably includes 2,2'-bipyridine and / or 1,10-phenanthroline, and more preferably 2,2'-bipyridine. The chelating agent is used to capture and remove specific metal impurities and to monitor the pickling process as a redox indicator.

[0043] In the present invention, the organic acid preferably includes glycolic acid and / or citric acid, and more preferably glycolic acid. The organic acid helps dissolve and remove impurities on the surface of the silicon micropowder through its acidity and complexation, and at the same time adjusts the pH value of the solution to maintain the stability of the pickling process.

[0044] In the present invention, the inorganic acid solution preferably includes one or more of hydrochloric acid solution, sulfuric acid solution, and nitric acid solution, and further preferably includes hydrochloric acid solution, sulfuric acid solution, or nitric acid solution, and more preferably is hydrochloric acid solution.

[0045] In the present invention, the mass ratio of the chelating agent to the organic acid is preferably 1-2:2-4, more preferably 1-1.5:2-3, and even more preferably 1:2.

[0046] In the present invention, the mass concentration of the chelating agent in the pickling solution is preferably 3-6%, more preferably 3.5-5%, and even more preferably 4%.

[0047] In the present invention, the mass concentration of the inorganic acid solution is preferably 15 to 20%, more preferably 16 to 19%, and even more preferably 18%.

[0048] In the present invention, in step (1), the acid leaching temperature is preferably room temperature; the acid leaching time is preferably 10 to 30 minutes, more preferably 15 to 25 minutes, and more preferably 20 minutes.

[0049] In the present invention, the ratio of the mass of the quartz ore to the volume of the pickling solution during the acid leaching in step (1) is not limited, as long as the quartz ore can be completely immersed in the pickling solution.

[0050] In the present invention, in step (1), after the acid leaching, the process preferably further comprises: filtering and washing in sequence.

[0051] In the present invention, the washing method is preferably: washing with a weak alkaline aqueous solution and water in sequence.

[0052] In the present invention, in step (1), the acid leaching has the function of removing impurities on the surface of silicon micropowder.

[0053] In the present invention, in step (2), the chlorinating agent preferably includes one or more of hydrogen chloride, chlorine gas, and ammonium chloride, and further preferably includes hydrogen chloride, chlorine gas or ammonium chloride, and more preferably is hydrogen chloride.

[0054] In the present invention, in step (2), the mass ratio of the chlorinating agent to the surface-decontaminated silicon micropowder is preferably 0.05 to 0.1:1, more preferably 0.08 to 0.1:1, and more preferably 0.08:1.

[0055] In the present invention, in step (2), the temperature of the chlorination roasting is preferably 600-900°C, more preferably 650-750°C, and more preferably 700°C; the time of the chlorination roasting is preferably 45-90 min, more preferably 55-65 min, and more preferably 60 min.

[0056] In the present invention, in step (2), the tail gas discharged during the chlorination roasting is preferably passed into a chemical absorption device for recovery, and a sodium hydroxide solution is selected according to the type of chlorinating agent for neutralization to ensure environmentally friendly production.

[0057] In the present invention, in step (2), the role of the chlorination roasting is: under certain conditions, with the help of the chlorinating agent, some metal components in the silicon powder are converted into gas phase or solid phase chlorides to separate the metal elements from other components. Since most of the metals, metal compounds and other compounds can react with chemically active chlorine to generate metal chlorides. Compared with the corresponding metal compounds, most of the various metal chlorides have the properties of low melting point, high volatility, and easy solubility in water at room temperature, and are easy to separate and remove.

[0058] In the present invention, in step (3), the mass concentration of the slurry obtained by mixing the ultrapure silicon powder with water is preferably 75-80%, more preferably 78-80%, and more preferably 80%.

[0059] In the present invention, in step (3), the rotation speed of the mixed grinding is preferably 3000-3500 r / min, more preferably 3100-3400 r / min, and more preferably 3200 r / min; the time of the mixed grinding is preferably 120-240 min, more preferably 150-210 min, and more preferably 180 min; the ball-to-material mass ratio of the mixed grinding is preferably 2.2-2.5:1, more preferably 2.3-2.5:1, and more preferably 2.4:1; the material of the grinding balls of the mixed grinding is preferably The grinding balls are zirconia balls; the grinding balls preferably include a mixture of balls with diameters of 1.2-1.4 mm, 1.6-1.8 mm, 2.0-2.2 mm and 2.4-2.6 mm; the mass ratio of grinding balls with diameters of 1.2-1.4 mm, grinding balls with diameters of 1.6-1.8 mm, grinding balls with diameters of 2.0-2.2 mm and grinding balls with diameters of 2.4-2.6 mm is preferably 0.5-1:1-2:0.5-1:3-4, further preferably 0.8-1:1.5-2:0.8-1:3.5-4, and more preferably 1:2:1:4.

[0060] In the present invention, in step (3), the particle size D of the slurry after mixed grinding is 50 It is preferably 1.6 to 2.2 μm, more preferably 1.6 to 1.8 μm, and even more preferably 1.6 μm; and the content of the particle size of the slurry after mixed grinding = 2 μm is preferably ≥ 85%.

[0061] In the present invention, in step (3), the drying temperature is preferably 550-750°C, more preferably 600-650°C, and more preferably 600°C.

[0062] In the present invention, in step (4), the silane coupling agent preferably includes one or more of silane coupling agent 4721, KH-550, and KH-171, and further preferably includes silane coupling agent 4721, KH-550 or KH-171, and more preferably is silane coupling agent 4721.

[0063] In the present invention, in step (4), the mass of the silane coupling agent is preferably 0.6-1% of the mass of the ultrafine ultrapure silicon powder, more preferably 0.8-1%, and even more preferably 1%.

[0064] In the present invention, in step (4), the temperature of the modification treatment is preferably 75-100°C, more preferably 80-90°C, and more preferably 80°C; the time of the modification treatment is preferably 20-40 min, more preferably 25-35 min, and more preferably 30 min.

[0065] The invention also provides a modified ultrafine ultrapure silicon powder.

[0066] The invention also provides an application of modified ultrafine ultrapure silicon powder in the preparation of rubber products.

[0067] In the present invention, the raw material composition of the rubber product is not limited, and any solution well known to those skilled in the art may be used.

[0068] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0069] Example 1

[0070] This embodiment provides a method for preparing modified ultrafine ultrapure silicon powder. The schematic diagram of the preparation process is as follows: Figure 1 As shown, the following steps are included:

[0071] (1) crushing the quartz ore twice by coarse crushing and medium crushing to obtain an ore with an average particle size of 20 mm; putting the ore into a vibration mill, grinding the ore by sliding and rolling the grinding medium in the mill cavity under the vibration of the mill, and obtaining an ore product with a mesh size of 80; soaking the ore product in a pickling solution (hydrochloric acid solution with a concentration of 18wt%) at room temperature, wherein the mass fraction of 2,2'-bipyridine in the pickling solution is 4%, the mass fraction of hydroxyacetic acid is 8%, and the mass ratio of 2,2'-bipyridine to hydroxyacetic acid is 1:2; after soaking for 20 minutes, filtering out the solid, and then washing with a sodium carbonate aqueous solution and clean water to obtain a silicon micropowder with impurities removed from the surface;

[0072] (2) The surface-decontaminated silicon micropowder is fully mixed with hydrogen chloride, the mass ratio of hydrogen chloride to surface-decontaminated silicon micropowder is 0.05:1, the mixed materials are sent to a chlorination furnace, the temperature is controlled for selective chlorination, the temperature is maintained at 700°C, the roasting time is 60 minutes, and ultra-pure silicon micropowder is obtained; the tail gas discharged from the chlorination furnace can be recycled by a chemical absorption device to ensure environmentally friendly production;

[0073] (3) Ultrapure silicon powder was put into a water mill at once, and an appropriate amount of water was added to adjust the slurry concentration to 75%. Zirconia beads of different diameters were placed in the water mill as grinding media (1.2-1.4 mm: 1.6-1.8 mm: 2.0-2.2 mm: 2.4-2.6 mm = 1:2:1:4). The speed was set to 3200 r / min, the ball-to-material mass ratio was set to 2.4:1, and the grinding was performed for 180 min. The D 50 =1.6μm, 2μm content reaches more than 85wt% after the slurry is poured out; the slurry is dehydrated, put into a hollow shaft stirring dryer, and dried at 600°C to obtain ultrafine ultrapure silicon powder;

[0074] (4) Add 0.6% by mass fraction of silane coupling agent 4721 (manufacturer: Evonik Specialty Chemicals (Shanghai) Co., Ltd.) to the ultrafine ultrapure silicon powder, and perform modification treatment at 80° C. for 30 min to obtain modified ultrafine ultrapure silicon powder; the modified product is dried and packaged.

[0075] Example 2

[0076] This embodiment provides a method for preparing modified ultrafine ultrapure silicon powder, comprising the following steps:

[0077] (1) crushing the quartz ore twice by coarse crushing and medium crushing to obtain an ore with an average particle size of 20 mm; putting the ore into a vibration mill, grinding the ore by sliding and rolling the grinding medium in the mill cavity under the vibration of the mill, and obtaining an ore product with a mesh size of 80; soaking the ore product in a pickling solution (hydrochloric acid solution with a concentration of 18wt%) at room temperature, wherein the mass fraction of 2,2'-bipyridine in the pickling solution is 4%, the mass fraction of hydroxyacetic acid is 8%, and the mass ratio of 2,2'-bipyridine to hydroxyacetic acid is 1:2; after soaking for 20 minutes, filtering out the solid, and then washing with a sodium carbonate aqueous solution and clean water to obtain a silicon micropowder with impurities removed from the surface;

[0078] (2) The surface-decontaminated silicon micropowder is fully mixed with hydrogen chloride, the mass ratio of hydrogen chloride to surface-decontaminated silicon micropowder is 0.08:1, the mixed materials are sent to a chlorination furnace, the temperature is controlled for selective chlorination, the temperature is maintained at 700°C, the roasting time is 60 minutes, and ultra-pure silicon micropowder is obtained; the tail gas discharged from the chlorination furnace can be passed into a chemical absorption device for recovery to ensure environmentally friendly production;

[0079] (3) Ultrapure silicon powder was put into a water mill at once, and an appropriate amount of water was added to adjust the slurry concentration to 75%. Zirconia beads of different diameters were placed in the water mill as grinding media (1.2-1.4 mm: 1.6-1.8 mm: 2.0-2.2 mm: 2.4-2.6 mm = 1:2:1:4). The speed was set to 3200 r / min, the ball-to-material mass ratio was set to 2.4:1, and the grinding was performed for 180 min. The D 50 =1.6μm, 2μm content reaches more than 85wt% after the slurry is poured out; the slurry is dehydrated, put into a hollow shaft stirring dryer, and dried at 600°C to obtain ultrafine ultrapure silicon powder;

[0080] (4) Add 0.6% by mass fraction of silane coupling agent 4721 (manufacturer: Evonik Specialty Chemicals (Shanghai) Co., Ltd.) to the ultrafine ultrapure silicon powder, and perform modification treatment at 80° C. for 30 min to obtain modified ultrafine ultrapure silicon powder; the modified product is dried and packaged.

[0081] Example 3

[0082] This embodiment provides a method for preparing modified ultrafine ultrapure silicon powder, comprising the following steps:

[0083] (1) crushing the quartz ore twice by coarse crushing and medium crushing to obtain an ore with an average particle size of 20 mm; putting the ore into a vibration mill, grinding the ore by sliding and rolling the grinding medium in the mill cavity under the vibration of the mill, and obtaining an ore product with a mesh size of 80; soaking the ore product in a pickling solution (hydrochloric acid solution with a concentration of 18wt%) at room temperature, wherein the mass fraction of 2,2'-bipyridine in the pickling solution is 4%, the mass fraction of hydroxyacetic acid is 8%, and the mass ratio of 2,2'-bipyridine to hydroxyacetic acid is 1:2; after soaking for 20 minutes, filtering out the solid, and then washing with a sodium carbonate aqueous solution and clean water to obtain a silicon micropowder with impurities removed from the surface;

[0084] (2) The surface-decontaminated silicon micropowder is fully mixed with hydrogen chloride, the mass ratio of hydrogen chloride to surface-decontaminated silicon micropowder is 0.1:1, the mixed materials are sent to a chlorination furnace, the temperature is controlled for selective chlorination, the temperature is maintained at 700°C, the roasting time is 60 minutes, and ultra-pure silicon micropowder is obtained; the tail gas discharged from the chlorination furnace can be passed into a chemical absorption device for recovery to ensure environmentally friendly production;

[0085] (3) Ultrapure silicon powder was put into a water mill at once, and an appropriate amount of water was added to adjust the slurry concentration to 75%. Zirconia beads of different diameters were placed in the water mill as grinding media (1.2-1.4 mm: 1.6-1.8 mm: 2.0-2.2 mm: 2.4-2.6 mm = 1:2:1:4). The speed was set to 3200 r / min, the ball-to-material mass ratio was set to 2.4:1, and the grinding was performed for 180 min. The D 50 =1.6μm, 2μm content reaches more than 85wt% after the slurry is poured out; the slurry is dehydrated, put into a hollow shaft stirring dryer, and dried at 600°C to obtain ultrafine ultrapure silicon powder;

[0086] (4) Add 0.6% by mass fraction of silane coupling agent 4721 (manufacturer: Evonik Specialty Chemicals (Shanghai) Co., Ltd.) to the ultrafine ultrapure silicon powder, and perform modification treatment at 80° C. for 30 min to obtain modified ultrafine ultrapure silicon powder; the modified product is dried and packaged.

[0087] Example 4

[0088] This embodiment provides a method for preparing modified ultrafine ultrapure silicon powder, comprising the following steps:

[0089] (1) crushing the quartz ore twice by coarse crushing and medium crushing to obtain an ore with an average particle size of 20 mm; putting the ore into a vibration mill, grinding the ore by sliding and rolling the grinding medium in the mill cavity under the vibration of the mill, and obtaining an ore product with a mesh size of 80; soaking the ore product in a pickling solution (hydrochloric acid solution with a concentration of 18wt%) at room temperature, wherein the mass fraction of 2,2'-bipyridine in the pickling solution is 4%, the mass fraction of hydroxyacetic acid is 8%, and the mass ratio of 2,2'-bipyridine to hydroxyacetic acid is 1:2; after soaking for 20 minutes, filtering out the solid, and then washing with a sodium carbonate aqueous solution and clean water to obtain a silicon micropowder with impurities removed from the surface;

[0090] (2) The surface-decontaminated silicon micropowder is fully mixed with hydrogen chloride, the mass ratio of hydrogen chloride to surface-decontaminated silicon micropowder is 0.08:1, the mixed materials are sent to a chlorination furnace, the temperature is controlled for selective chlorination, the temperature is maintained at 700°C, the roasting time is 60 minutes, and ultra-pure silicon micropowder is obtained; the tail gas discharged from the chlorination furnace can be passed into a chemical absorption device for recovery to ensure environmentally friendly production;

[0091] (3) Ultrapure silicon powder was put into a water mill at once, and an appropriate amount of water was added to adjust the slurry concentration to 75%. Zirconia beads of different diameters were placed in the water mill as grinding media (1.2-1.4 mm: 1.6-1.8 mm: 2.0-2.2 mm: 2.4-2.6 mm = 1:2:1:4). The speed was set to 3200 r / min, the ball-to-material mass ratio was set to 2.4:1, and the grinding was performed for 180 min. The D 50 =1.6μm, 2μm content reaches more than 85wt% after the slurry is poured out; the slurry is dehydrated, put into a hollow shaft stirring dryer, and dried at 600°C to obtain ultrafine ultrapure silicon powder;

[0092] (4) Add 0.8% by mass fraction of silane coupling agent 4721 (manufacturer: Evonik Specialty Chemicals (Shanghai) Co., Ltd.) to the ultrafine ultrapure silicon powder, and perform modification treatment at 80° C. for 30 min to obtain modified ultrafine ultrapure silicon powder; the modified product is dried and packaged.

[0093] Example 5

[0094] This embodiment provides a method for preparing modified ultrafine ultrapure silicon powder, comprising the following steps:

[0095] (1) crushing the quartz ore twice by coarse crushing and medium crushing to obtain an ore with an average particle size of 20 mm; putting the ore into a vibration mill, grinding the ore by sliding and rolling the grinding medium in the mill cavity under the vibration of the mill, and obtaining an ore product with a mesh size of 80; soaking the ore product in a pickling solution (hydrochloric acid solution with a concentration of 18wt%) at room temperature, wherein the mass fraction of 2,2'-bipyridine in the pickling solution is 4%, the mass fraction of hydroxyacetic acid is 8%, and the mass ratio of 2,2'-bipyridine to hydroxyacetic acid is 1:2; after soaking for 20 minutes, filtering out the solid, and then washing with a sodium carbonate aqueous solution and clean water to obtain a silicon micropowder with impurities removed from the surface;

[0096] (2) The surface-decontaminated silicon micropowder is fully mixed with hydrogen chloride, the mass ratio of hydrogen chloride to surface-decontaminated silicon micropowder is 0.08:1, the mixed materials are sent to a chlorination furnace, the temperature is controlled for selective chlorination, the temperature is maintained at 700°C, the roasting time is 60 minutes, and ultra-pure silicon micropowder is obtained; the tail gas discharged from the chlorination furnace can be passed into a chemical absorption device for recovery to ensure environmentally friendly production;

[0097] (3) Ultrapure silicon powder was put into a water mill at once, and an appropriate amount of water was added to adjust the slurry concentration to 75%. Zirconia beads of different diameters were placed in the water mill as grinding media (1.2-1.4 mm: 1.6-1.8 mm: 2.0-2.2 mm: 2.4-2.6 mm = 1:2:1:4). The speed was set to 3200 r / min, the ball-to-material mass ratio was set to 2.4:1, and the grinding was performed for 180 min. The D 50 =1.6μm, 2μm content reaches more than 85wt% after the slurry is poured out; the slurry is dehydrated, put into a hollow shaft stirring dryer, and dried at 600°C to obtain ultrafine ultrapure silicon powder;

[0098] (4) Add 1% by mass of silane coupling agent 4721 (manufacturer: Evonik Specialty Chemicals (Shanghai) Co., Ltd.) to the ultrafine ultrapure silicon powder, and perform modification treatment at 80° C. for 30 min to obtain modified ultrafine ultrapure silicon powder; the modified product is dried and packaged.

[0099] Comparative Example 1

[0100] This comparative example provides a method for preparing modified ultrafine silicon powder, comprising the following steps:

[0101] (1) crushing the quartz ore twice by coarse crushing and medium crushing to obtain an ore with an average particle size of 20 mm; putting the ore into a vibration mill, grinding the ore by sliding and rolling the grinding medium in the mill cavity under the vibration of the mill, and obtaining an ore product with a mesh size of 80; soaking the ore product in a pickling solution (hydrochloric acid solution with a concentration of 18wt%) at room temperature, wherein the mass fraction of 2,2'-bipyridine in the pickling solution is 4%, the mass fraction of hydroxyacetic acid is 8%, and the mass ratio of 2,2'-bipyridine to hydroxyacetic acid is 1:2; after soaking for 20 minutes, filtering out the solid, and then washing with a sodium carbonate aqueous solution and clean water to obtain a silicon micropowder with impurities removed from the surface;

[0102] (2) The surface-removed silicon micropowder was put into a water mill at once, and an appropriate amount of water was added to adjust the slurry concentration to 75%. Zirconia beads of different diameters were placed in the water mill as grinding media (1.2-1.4 mm: 1.6-1.8 mm: 2.0-2.2 mm: 2.4-2.6 mm = 1:2:1:4). The speed was set to 3200 r / min, the ball-to-material mass ratio was set to 2.4:1, and the grinding was performed for 180 min. The D 50 =1.6μm, 2μm content reaches more than 85wt% and then the slurry is poured out; the slurry is dehydrated and put into a hollow shaft stirring dryer and dried at 600°C to obtain ultrafine silicon powder;

[0103] (3) Add 1% by mass fraction of silane coupling agent 4721 (manufacturer: Evonik Specialty Chemicals (Shanghai) Co., Ltd.) to the ultrafine silicon powder, and perform modification treatment at 80° C. for 30 minutes to obtain modified ultrafine silicon powder; the modified product is dried and packaged.

[0104] Comparative Example 2

[0105] This comparative example provides a method for preparing ultrafine ultrapure silicon powder, comprising the following steps:

[0106] (1) crushing the quartz ore twice by coarse crushing and medium crushing to obtain an ore with an average particle size of 20 mm; putting the ore into a vibration mill, grinding the ore by sliding and rolling the grinding medium in the mill cavity under the vibration of the mill, and obtaining an ore product with a mesh size of 80; soaking the ore product in a pickling solution (hydrochloric acid solution with a concentration of 18wt%) at room temperature, wherein the mass fraction of 2,2'-bipyridine in the pickling solution is 4%, the mass fraction of hydroxyacetic acid is 8%, and the mass ratio of 2,2'-bipyridine to hydroxyacetic acid is 1:2; after soaking for 20 minutes, filtering out the solid, and then washing with a sodium carbonate aqueous solution and clean water to obtain a silicon micropowder with impurities removed from the surface;

[0107] (2) The surface-decontaminated silicon micropowder is fully mixed with hydrogen chloride, the mass ratio of hydrogen chloride to surface-decontaminated silicon micropowder is 0.08:1, the mixed materials are sent to a chlorination furnace, the temperature is controlled for selective chlorination, the temperature is maintained at 700°C, the roasting time is 60 minutes, and ultra-pure silicon micropowder is obtained; the tail gas discharged from the chlorination furnace can be passed into a chemical absorption device for recovery to ensure environmentally friendly production;

[0108] (3) Ultrapure silicon powder was put into a water mill at once, and an appropriate amount of water was added to adjust the slurry concentration to 75%. Zirconia beads of different diameters were placed in the water mill as grinding media (1.2-1.4 mm: 1.6-1.8 mm: 2.0-2.2 mm: 2.4-2.6 mm = 1:2:1:4). The speed was set to 3200 r / min, the ball-to-material mass ratio was set to 2.4:1, and the grinding was performed for 180 min. The D 50 =1.6μm, 2μm content reaches more than 85wt% when the slurry is poured out; the slurry is dehydrated, put into a hollow shaft stirring dryer, and dried at 600°C to obtain ultrafine ultrapure silicon powder; the product is dried and packaged.

[0109] The products obtained in Examples 1 to 5 and Comparative Examples 1 to 2 and the quartz ore were tested, and the results are shown in Table 1.

[0110] Table 1. Test data of the products obtained in Examples 1 to 5 and Comparative Examples 1 to 2 and the quartz ore

[0111]

[0112]

[0113] Table 1 shows the test data results of the powders obtained in each example. It can be seen that the purity of the silicon micropowder calcined with the addition of a chlorinating agent is significantly improved, and the best ratio of the amount of the chlorinating agent to the mass of the powder is 0.08:1; at the same time, the activation degree is the highest when the amount of the silane coupling agent 4721 is 1wt%, indicating that the activation effect is best at this time.

[0114] Application Examples

[0115] The silicon powder products of the above-mentioned embodiments 1 to 5 and comparative examples 1 to 2 were respectively added with 1.2% dispersant 5040, and water was added to form a 15wt% dispersion, and then subjected to ultrasonic treatment for 30min and then aged for 12h and centrifuged to obtain silicon powder slurries; according to the following formula: 100 parts of latex (Jinxing latex 60.5), 0.8 parts of sulfur, 1.0 parts of zinc oxide, 0.5 parts of ultra-fast rubber vulcanization accelerator zinc diethyl dithiocarbamate (Zhongshan Dixin Chemical Co., Ltd.), 0.4 parts of vulcanization accelerator PX (Guangzhou Dongxin Chemical Co., Ltd.), 0.7 parts of potassium hydroxide, 4 parts of silicon powder slurry, respectively prepared into latex gloves. The performance of latex gloves with different silicon powders was tested, and the blank experiment was a formula without silicon powder. The tensile strength, 300% tensile strength, and elongation at break were tested according to the standard of GB / T 528-2009, and the results are shown in Table 2.

[0116] Table 2. Test data of application examples

[0117]

[0118]

[0119] As can be seen from Table 2, after adding high-purity ultrafine silicon powder, the stress that ultrafine particles can withstand is greater than that of the base rubber, which ensures the system's ability to resist deformation and improves the tensile strength of the material. Ultrafine particles can be oriented together with rubber molecular chains, which improves the overall deformation resistance of the material and the elongation at break of the product. After the powder is modified, the interface between the polar powder and the non-polar rubber hydrocarbon is improved, the dispersibility and physical cross-linking effect are improved, making the application effect of silicon powder products in latex gloves better.

[0120] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing modified ultrafine ultrapure silicon powder, characterized in that: The following steps are involved: (1) mixing the quartz ore with the pickling solution and performing acid leaching to obtain silicon micropowder with surface impurities removed; (2) mixing the surface-removed silicon micropowder with a chlorinating agent and performing chlorination roasting to obtain ultrapure silicon micropowder; (3) mixing and grinding the ultrapure silicon powder with water; drying the slurry obtained by mixing and grinding to obtain ultrafine ultrapure silicon powder; (4) The ultrafine ultrapure silicon powder is mixed with a silane coupling agent and subjected to modification treatment to obtain modified ultrafine ultrapure silicon powder.

2. The preparation method according to claim 1, characterized in that: In step (1), the pickling solution comprises a mixture of a chelating agent, an organic acid and an inorganic acid solution; The chelating agent includes 2,2'-bipyridine and / or 1,10-phenanthroline; The organic acid includes glycolic acid and / or citric acid; The inorganic acid solution includes one or more of hydrochloric acid solution, sulfuric acid solution, and nitric acid solution; The mass ratio of the chelating agent to the organic acid is 1-2:2-4; The mass concentration of the chelating agent in the pickling solution is 3-6%; The mass concentration of the inorganic acid solution is 15-20%.

3. The preparation method according to claim 1 or 2, characterized in that: In step (1), the acid leaching temperature is room temperature, and the acid leaching time is 10 to 30 minutes.

4. The preparation method according to claim 1, characterized in that: In step (2), the chlorinating agent includes one or more of hydrogen chloride, chlorine, and ammonium chloride; The mass ratio of the chlorinating agent to the surface-decontaminated silicon micropowder is 0.05-0.1:

1.

5. The preparation method according to claim 1 or 5, characterized in that: In step (2), the temperature of the chlorination roasting is 600-900° C., and the time of the chlorination roasting is 45-90 minutes.

6. The preparation method according to claim 1, characterized in that: In step (3), the rotation speed of the mixed grinding is 3000-3500 r / min, the time of the mixed grinding is 120-240 min, the mass ratio of the balls and materials in the mixed grinding is 2.2-2.5:1, the grinding balls in the mixed grinding include a mixture of grinding balls with diameters of 1.2-1.4 mm, 1.6-1.8 mm, 2.0-2.2 mm and 2.4-2.6 mm, and the mass ratio of grinding balls with diameters of 1.2-1.4 mm, grinding balls with diameters of 1.6-1.8 mm, grinding balls with diameters of 2.0-2.2 mm and grinding balls with diameters of 2.4-2.6 mm is 0.5-1:1-2:0.5-1:3-4; The mass concentration of the slurry obtained by mixing the ultrapure silicon powder with water is 75-80%.

7. The preparation method according to claim 1, characterized in that: In step (4), the silane coupling agent includes one or more of silane coupling agent 4721, KH-550, and KH-171; The mass of the silane coupling agent is 0.6-1% of the mass of the ultrafine ultrapure silicon powder.

8. The preparation method according to claim 1 or 7, characterized in that: In step (4), the temperature of the modification treatment is 75 to 100° C., and the time of the modification treatment is 20 to 40 minutes.

9. A modified ultrafine ultrapure silicon powder obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the modified ultrafine ultrapure silicon powder according to claim 9 in the preparation of rubber products.

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