Modified matt silica powder, preparation method thereof and application of modified matt silica powder in matt paint

Abstract

The invention provides modified matt silica powder, a preparation method thereof and application of the modified matt silica powder in matt paint, and belongs to the technical field of fine chemical engineering. Natural crystal type quartz ore is taken as a raw material, superfine silica powder raw powder is obtained by grinding twice, and polyamide wax is adopted for surface modification of the raw powder, so that the diffuse reflection efficiency of the silica powder is improved; hydrophilic fumed silica is compounded, and gamma-methacryloxypropyltrimethoxysilane and catechol are used as modified binders, so that the fumed silica is adsorbed on the surface of the silica micropowder, thereby improving the porosity of the surface of the silica micropowder and improving the extinction effect. When the prepared modified extinction silica powder is independently applied to matte paint, compared with traditional silica powder, the gloss of a paint film can be effectively reduced, and the glossiness required by a product is achieved; compared with gas-phase method silicon dioxide, the silicon dioxide prepared by the preparation method has the rheological property and various mechanical properties of a paint film, and has relatively high universality.

Description

Technical Field

[0001] The present invention relates to the technical field of fine chemicals, and in particular to modified matte silicon micropowder, a preparation method thereof, and application thereof in matte paint. Background Art

[0002] Matte paint refers to a type of paint with a glossiness of less than 20 (at a 60° angle). Its visual effect is elegant and soft, and therefore it is widely used in schools, hospitals, hotels, and other places that require soft lighting, quietness, comfort, and elegance. At present, matte paint is mainly obtained through two methods: physical and chemical matting. Physical matting refers to the method of adding matting agents such as nano-fumed silica. Its disadvantages are obvious, resulting in large changes in the rheological properties of the paint, increased brittleness of the coating, easy breakage and shedding, and reduced resistance to rubbing, bending, and friction. Chemical matting mainly synthesizes specific polymer resins through chemical reactions, and utilizes the relationship between their structure and properties or the differences in properties within (between) components to achieve a matting effect on the paint film itself without adding a matting agent. However, the application field of the resin itself has certain limitations, so the versatility of matting is poor.

[0003] Silica micropowder is a micropowder made from natural quartz (SiO2) or fused quartz (amorphous SiO2 after natural quartz is melted at high temperature and cooled) through multiple processes such as crushing, ball milling (or vibration, air flow milling), flotation, pickling purification, and high-purity water treatment. It has significant advantages such as high hardness, low thermal expansion coefficient, excellent dielectric properties, high thermal conductivity, and good suspension performance. Therefore, it is widely used in the fields of coatings, rubber, adhesives, etc. At the same time, since the surface roughness of silica micropowder is higher than that of general non-metallic mineral materials, it also has a certain matting effect. However, conventional silica micropowder is not rough enough, so its diffuse reflection efficiency of light is low. Direct application of it in matte paint formula cannot achieve the required gloss requirement, and it is necessary to add a matting agent to assist in matting. Summary of the Invention

[0004] The purpose of the present invention is to provide a modified matte silica powder, a preparation method thereof and an application thereof in matte paint. The modified matte silica powder used alone in matte paint can meet the gloss requirements of the paint film while taking into account the rheological properties and various mechanical properties of the coating.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing modified matte silicon micropowder, comprising the following steps:

[0007] The crystalline quartz ore is crushed, and the obtained quartz particles are first ground to obtain coarse silicon micropowder;

[0008] The coarse silicon micropowder powder is mixed with a grinding aid, subjected to a second grinding, and then classified to obtain raw silicon micropowder powder;

[0009] The silicon micropowder raw powder is subjected to a first mixing process, then mixed with a first modifier, subjected to a first modification process, and then subjected to a first cold mixing process to obtain a first modified silicon micropowder;

[0010] After performing a second mixing of the first modified silicon micropowder and fumed silica, the resulting mixture is mixed with a second modifier and subjected to a second modification treatment to obtain a second modified silicon micropowder;

[0011] performing a second cold mixing on the second modified silica powder to obtain modified matte silica powder;

[0012] The first modifier is polyamide wax;

[0013] The second modifier is γ-methacryloxypropyltrimethoxysilane and catechol.

[0014] Preferably, the diameter of the quartz particles is 10 to 35 mm; the particle size D of the coarse silicon powder is 50 14~16μm, D 97 It is 69~74μm.

[0015] Preferably, the grinding aid is sodium polyacrylate and polyethylene glycol, the mass ratio of the sodium polyacrylate to the polyethylene glycol is 3-5:1; the molecular weight of the sodium polyacrylate is 1000-2000; the molecular weight of the polyethylene glycol is 3500-4000.

[0016] Preferably, the grinding aid is added by diluting with water; the mass ratio of water to grinding aid is 6-8:1; the mass of the grinding aid accounts for 6-8‰ of the mass of the coarse silicon powder.

[0017] Preferably, the conditions for the second grinding include: the grinding media are ceramic balls of different diameters, the grinding media filling rate is 55-65%, the diameters of the grinding media in the front chamber are 60 mm and 50 mm, and the ratio of the 60 mm diameter ceramic balls to the 50 mm diameter ceramic balls is 2-3:1, the diameters of the grinding media in the middle chamber are 50 mm and 40 mm, and the ratio of the 50 mm diameter ceramic balls to the 40 mm diameter ceramic balls is 1-2:1, and the diameters of the grinding media in the rear chamber are 30 mm, 20 mm, and 10 mm, and the ratio of the 30 mm diameter ceramic balls to the 20 mm diameter ceramic balls to the 10 mm diameter ceramic balls is 1:1-2:2-3;

[0018] The D of the silicon micropowder raw powder 50 2.0~2.2μm, D 97 5.8~6.0μm.

[0019] Preferably, the material temperature of the first mixture is 70-80°C, the mixing time is 10-20 min, the rotation speed is 400-500 r / min; the particle size D of the first modifier is 50 The particle size of the first modifier is 5.0 μm, the mass of the first modifier is 4 to 6‰ of the total mass of the silicon micropowder original powder; the time of the first modification treatment is 20 to 30 minutes; the time of the first cold mixing is 5 to 10 minutes, and the speed of the cold mixer is 200 to 300 r / min.

[0020] Preferably, the fumed silica is hydrophilic fumed silica, and the specific surface area of ​​the fumed silica is 400 m 2 / g, primary particle size <7nm; the mass of the fumed silica is 3-5% of the mass of the first modified silicon powder; the second mixing time is 10-20min, the high mixer speed is 600-800r / min, and the material temperature is 40-50℃.

[0021] Preferably, the mass ratio of γ-methacryloxypropyltrimethoxysilane to catechol is 3 to 4:1, and the mass of the second modifier is 2 to 3% of the total mass of the mixed material obtained by the second mixing; the material temperature of the second modification treatment is 90 to 100°C, the time is 20 to 30 minutes, and the high mixer speed is 600 to 800 r / min; the second cold mixing time is 5 to 10 minutes, and the cold mixer speed is 200 to 300 r / min.

[0022] The present invention provides modified matte silicon micropowder prepared by the preparation method described in the above technical solution.

[0023] The present invention provides the use of the modified matte silica powder described in the above technical solution in matte paint.

[0024] The invention provides a preparation method of modified matte silica micropowder. Natural crystalline quartz ore is used as a raw material, which has poor fluidity and is more conducive to forming a rough paint film surface when used in matte paint, thereby achieving a better material matting effect. Ultrafine silica micropowder raw powder is obtained by two grinding steps, and the raw powder is surface-modified by using polyamide wax to improve the diffuse reflection efficiency of the silica micropowder. Hydrophilic fumed silica is compounded, and the fumed silica has a large specific surface area and a high surface porosity, which can further improve the diffuse reflection performance of the silica micropowder surface. γ-methacryloxypropyltrimethoxysilane and catechol are used as modified binders, so that the fumed silica is adsorbed on the silica micropowder surface, thereby increasing the porosity of the silica micropowder surface and improving the matting effect. When the modified matte silica powder prepared by the present invention is used alone in matte paint, it can effectively reduce the gloss of the paint film compared to traditional silica powder, achieving the required gloss of the product. Compared with fumed silica, it can take into account the rheological properties and various mechanical properties of the paint film, while also having strong versatility. Therefore, when the modified matte silica powder of the present invention is used alone in matte paint, it can meet the required gloss of the paint film while taking into account the rheological properties and various mechanical properties of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The figure is a flow chart for preparing the modified matte silicon powder of the present invention. DETAILED DESCRIPTION

[0026] In the present invention, unless otherwise specified, the required raw materials or reagents are commercially available products well known to those skilled in the art.

[0027] like Figure 1 As shown, the present invention provides a method for preparing modified matte silicon powder, comprising the following steps:

[0028] The crystalline quartz ore is crushed, and the obtained quartz particles are first ground to obtain coarse silicon micropowder;

[0029] The coarse silicon micropowder powder is mixed with a grinding aid, subjected to a second grinding, and then classified to obtain raw silicon micropowder powder;

[0030] The silicon micropowder raw powder is subjected to a first mixing process, then mixed with a first modifier, subjected to a first modification process, and then subjected to a first cold mixing process to obtain a first modified silicon micropowder;

[0031] After performing a second mixing of the first modified silicon micropowder and fumed silica, the resulting mixture is mixed with a second modifier and subjected to a second modification treatment to obtain a second modified silicon micropowder;

[0032] performing a second cold mixing on the second modified silica powder to obtain modified matte silica powder;

[0033] The first modifier (corresponding to Figure 1 The 1# modifier is polyamide wax;

[0034] The second modifier (corresponding to Figure 1 The second modifier is γ-methacryloxypropyltrimethoxysilane and catechol.

[0035] The present invention crushes crystalline quartz ore, and performs a first grinding on the obtained quartz particles to obtain coarse silicon micropowder.

[0036] In the present invention, the crystalline quartz ore is preferably a natural crystalline quartz ore with a silicon dioxide content of ≥99%. Its particle morphology is angular, so its fluidity is worse than that of a spherical particle. When used in matte paint, it is more conducive to forming a rough paint film surface, thereby achieving a better material matting effect.

[0037] In the present invention, the crystalline quartz ore is preferably washed, dried, crushed by jaw crushing and crushed by hammer crushing in sequence to obtain quartz particles.

[0038] In the present invention, the diameter of the quartz particles is preferably 10 to 35 mm.

[0039] In the present invention, the quartz particles are preferably conveyed into a European grinding mill of model MTW145G via a spiral cutter for first grinding to obtain coarse silicon micropowder; the D of the coarse silicon micropowder is 50 14 to 16 μm, more preferably 15.37 to 15.82 μm, D 97 The present invention has no special limitation on the first grinding process, and the desired particle size of the coarse silicon micropowder can be obtained by methods well known in the art.

[0040] After obtaining the coarse silicon micropowder powder, the present invention mixes the coarse silicon micropowder powder with a grinding aid, performs a second grinding, and then classifies to obtain raw silicon micropowder powder.

[0041] In the present invention, the grinding aid is preferably sodium polyacrylate and polyethylene glycol, with the mass ratio of sodium polyacrylate to polyethylene glycol preferably being 3-5:1, more preferably 4:1. The molecular weight of the sodium polyacrylate is preferably 1000-2000, more preferably 1000-1200, 1200-1500, or 1600-1800. The molecular weight of the polyethylene glycol is preferably 3500-4000, more preferably 3500-3600, 3600-3800, or 3800-4000. The grinding aid of the present invention is used to improve the viscosity of the material and reduce the probability of ultrafine particle agglomeration, but is not intended to improve the fluidity and dispersibility of the product in downstream applications. Therefore, a low-molecular-weight dispersant is selected as the grinding aid to improve grinding efficiency.

[0042] The present invention preferably conveys the coarse silicon powder into a three-bin ball mill with a specification of 3.2m*13m via a spiral auger, and adds a grinding aid at the front end of the spiral auger conveying system for a second grinding.

[0043] The volume ratio of the front bin, middle bin and rear bin of the three-bin ball mill of the present invention is preferably 1:1:3. The front bin is mainly used for further coarse grinding, the middle bin plays a transition role, and the rear bin focuses on ultrafine grinding. Since the feed material is powder, the front bin accounts for a smaller proportion.

[0044] The present invention preferably adds the grinding aid by diluting with water; the mass ratio of the water to the grinding aid is preferably 6-8:1, more preferably 7:1; the mass of the grinding aid preferably accounts for 6-8‰ of the mass of the coarse silicon powder, more preferably 7‰.

[0045] In the present invention, the conditions for the second grinding preferably include: the grinding media are ceramic balls of different diameters, the grinding media filling rate is 55-65%, more preferably 60%, the diameters of the grinding media in the front chamber are 60 mm and 50 mm, and the number ratio of ceramic balls with a diameter of 60 mm to ceramic balls with a diameter of 50 mm is 2-3:1, more preferably 3:1, the diameters of the grinding media in the middle chamber are 50 mm and 40 mm, and the number ratio of ceramic balls with a diameter of 50 mm to ceramic balls with a diameter of 40 mm is 1-2:1, more preferably 2:1, the diameters of the grinding media in the rear chamber are 30 mm, 20 mm and 10 mm, and the number ratio of ceramic balls with a diameter of 30 mm, ceramic balls with a diameter of 20 mm and ceramic balls with a diameter of 10 mm is 1:1-2:2-3, more preferably 1:2:3.

[0046] The present invention adopts a European-style grinding mill and a three-bin ball mill in series grinding, utilizes the European-style grinding mill to obtain coarse silicon micropowder, improves the feed fineness of the ball mill, thereby improving the grinding efficiency of the ball mill, and more effectively performs ultrafine grinding on the silicon micropowder to obtain ultrafine silicon micropowder raw powder.

[0047] In the present invention, the D of the silicon micropowder raw powder is 50 2.0 to 2.2 μm, more preferably 2.04 to 2.19 μm, further preferably 2.12 μm, D 97 It is 5.8 to 6.0 μm, more preferably 5.84 to 5.94 μm.

[0048] In the present invention, the silicon micropowder after the second grinding is preferably classified and then detected by a BT-9300ST laser particle size analyzer to meet the above-mentioned silicon micropowder raw powder fineness requirements before entering the raw powder silo.

[0049] After obtaining the raw silicon micropowder, the present invention performs a first mixing on the raw silicon micropowder, mixes it with a first modifier, performs a first modification treatment, and then performs a first cold mixing to obtain a first modified silicon micropowder.

[0050] The present invention has no special limitation on the 1# high speed mixer, 2# high speed mixer, 3# high speed mixer, 1# cold mixer and 2# cold mixer described herein. Any high speed mixer well known in the art can be used. The numbers only represent that the materials are placed in different high speed mixers, and do not represent that the high speed mixers have differences.

[0051] In the present invention, the raw silicon micropowder is preferably conveyed into the 1# high-speed mixer via a spiral auger for high-speed stirring. The material temperature of the first mixture is preferably 70-80°C, more preferably 70-75°C, the mixing time is preferably 10-20 min, more preferably 10-15 min, and the high-speed mixer speed is 400-500 r / min, more preferably 450 r / min.

[0052] In the present invention, the first modifier is polyamide wax (melting point is 70°C); the particle size D of the first modifier is 50 The first modifier is preferably 5.0 μm, and the mass of the first modifier is preferably 4-6‰ of the total mass of the original silicon micropowder, more preferably 5‰. In the first modification, the polyamide wax molecules are smaller than the high molecular weight polymer, and coating the surface of the silicon micropowder helps to improve the diffuse reflection efficiency of the material, thereby improving the extinction performance.

[0053] In the present invention, the first modifier is preferably added to the 1# high speed mixer, the first modification treatment is performed under the first mixing conditions, and the resulting material is fed into the 1# cold mixer for the first cold mixing.

[0054] In the present invention, the time of the first modification treatment is preferably 20 to 30 minutes, more preferably 20 to 25 minutes; the time of the first cold mixing is preferably 5 to 10 minutes, more preferably 5 to 8 minutes, and the speed of the cold mixer is preferably 200 to 300 r / min, more preferably 250 r / min.

[0055] After obtaining the first modified silicon micropowder, the present invention performs a second mixing process on the first modified silicon micropowder and fumed silica, and then mixes the obtained mixture with a second modifier to perform a second modification process to obtain the second modified silicon micropowder.

[0056] In the present invention, the fumed silica is a hydrophilic fumed silica, and the specific surface area of ​​the fumed silica is preferably 400 m 2 / g, the primary particle size is preferably <7nm; the mass of the fumed silica is preferably 3-5% of the mass of the first modified silicon powder, more preferably 4%. The present invention has no particular limitation on the source of the fumed silica, and any commercially available product known in the art can be used.

[0057] In the present invention, the material in the 1# cold mixer is preferably transported through a pipeline into the 2# high-speed mixer, and fumed silica is added at the same time for a second mixing; the second mixing time is preferably 10 to 20 minutes, more preferably 15 minutes, the high-speed mixer speed is preferably 600 to 800 r / min, more preferably 700 r / min, and the material temperature is preferably 40 to 50°C, more preferably 45°C.

[0058] After the second mixing is completed, the present invention preferably conveys the material into the 3# high-speed mixer through a spiral auger with an electric heating function, and adds the second modifier in the form of solvent dilution at the front end of the conveying system. The temperature of the material in the spiral auger conveying system is 60-70°C, more preferably 65°C; the second modification treatment is carried out in the 3# high-speed mixer to obtain the second modified silicon micropowder.

[0059] In the present invention, the second modifier is γ-methacryloxypropyltrimethoxysilane and catechol; the mass ratio of γ-methacryloxypropyltrimethoxysilane to catechol is preferably 3-4:1, more preferably 4:1, and the mass of the second modifier is preferably 2-3% of the total mass of the mixed material obtained by the second mixing, more preferably 2.5%; the second modifier acts as a binder, and the polyhydroxy functional groups on the modifier are combined with the hydroxyl groups on the surfaces of the silicon micropowder and the fumed silica, so that the fumed silica is adsorbed on the surface of the silicon micropowder, thereby increasing the porosity of the silicon micropowder surface and improving the matting effect.

[0060] In the present invention, the dilution solvent used for the solvent dilution is preferably ethanol, and the mass ratio of the ethanol to the second modifier is preferably 2 to 3:1, more preferably 3:1.

[0061] In the present invention, the material temperature of the second modification treatment is preferably 90-100°C, more preferably 95°C, the time is preferably 20-30 min, more preferably 25 min, and the high mixer speed is preferably 600-800 r / min, more preferably 700 r / min.

[0062] After obtaining the second modified silicon micropowder, the present invention puts the second modified silicon micropowder into a 2# cold mixer for cold mixing and sieving to obtain modified matte silicon micropowder.

[0063] In the present invention, the second cold mixing time is preferably 5 to 10 minutes, more preferably 8 minutes, and the speed of the cold mixer is preferably 200 to 300 r / min, more preferably 250 r / min.

[0064] The present invention provides modified matte silicon micropowder prepared by the preparation method described in the above technical solution.

[0065] The present invention provides the use of the modified matte silica powder described in the above technical solution in matte paint. The present invention has no particular limitation on the method of the application, and the application can be carried out according to methods well known in the art.

[0066] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited by the specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The experimental methods described in the embodiments of the present invention are all conventional methods unless otherwise specified.

[0067] The following experimental methods and detection methods, unless otherwise specified, are conventional methods; the following reagents and raw materials, unless otherwise specified, are commercially available.

[0068] Example 1

[0069] Select natural crystalline quartz ore with a silicon dioxide content of ≥99%, and after cleaning, drying, crushing with jaw crusher and hammer crushing, obtain quartz particles with a diameter of 10-35mm, which are conveyed by spiral cutter into the European version mill model MTW145G for primary grinding to obtain D 50 15.82μm, D 97 The 73.29μm coarse silicon micropowder is conveyed by a spiral cutter into a three-compartment ball mill with a specification of 3.2m*13m (the volume ratio of the front compartment: middle compartment: rear compartment of the three-compartment ball mill is 1:1:3). The grinding medium filling rate is 55%, the number of grinding media in the front compartment is 60mm:50mm=2:1, the number of grinding media in the middle compartment is 50mm:40mm=1:1, and the number of grinding media in the rear compartment is 30mm:20mm:10m m=1:1:2, and grinding aid (sodium polyacrylate: polyethylene glycol mass ratio = 3:1, sodium polyacrylate molecular weight 1000~1200, polyethylene glycol molecular weight 3500~3600) accounting for 6‰ of the mass of the coarse silicon powder is added at the front end of the spiral auger conveying system by diluting with water (water: grinding aid = 6:1, mass ratio). The ground silicon powder is classified and enters the raw powder silo. The product is tested by BT-9300ST laser particle size analyzer. 50 2.19μm, D 97 The particle size is 5.94 μm, and the raw silicon micropowder is obtained;

[0070] The raw silicon micropowder is conveyed into the 1# high-speed mixer through a spiral cutter for high-speed stirring. The material temperature of the high-speed mixer is 70℃, the mixing is 10min, the high-speed mixer speed is 400r / min, and polyamide wax (melting point is 70℃, particle size D) accounting for 4‰ of the raw silicon micropowder mass is added. 505.0 μm), continue mixing for 20 minutes, then enter the 1# cold mixer for cold mixing for 5 minutes, the cold mixer speed is 200 r / min, and the first modified silicon powder is obtained;

[0071] The material in the cold mixer is transported to the 2# high speed mixer through the pipeline, and fumed silica (specific surface area of ​​400m2) accounting for 3% of the mass of the first modified silicon powder is added. 2 / g, primary particle size <7 nm), high-speed mixing for 10 minutes, high-speed mixer speed of 600 r / min, material temperature of 40 ° C, the mixed material is conveyed into the 3# high-speed mixer through a spiral cutter with an electric heating function (temperature of 60 ° C), and the second modifier (γ-methacryloxypropyltrimethoxysilane: catechol mass ratio = 3: 1) accounting for 2% of the mixed material is added at the front end of the conveying system by solvent dilution (ethanol: second modifier mass ratio = 2: 1). The material is mixed at high speed in the 3# high-speed mixer for 20 minutes, the high-speed mixer speed is 600 r / min, and the material temperature is 90 ° C. After the mixing is completed, the material enters the 2# cold mixer for cooling treatment, the cold mixing time is 5 minutes, the cold mixer speed is 200 r / min, and the modified matte silica powder is sieved.

[0072] Example 2

[0073] Select natural crystalline quartz ore with a silicon dioxide content of ≥99%, and after cleaning, drying, crushing with jaw crusher and hammer crushing, obtain quartz particles with a diameter of 10-35mm, which are conveyed by spiral cutter into the European version mill model MTW145G for primary grinding to obtain D 50 15.37 μm, D 97 The 69.04μm coarse silicon micropowder is conveyed by a spiral cutter into a three-compartment ball mill with a specification of 3.2m*13m (the volume ratio of the front compartment: middle compartment: rear compartment of the three-compartment ball mill is 1:1:3). The grinding medium filling rate is 60%, the quantity ratio of the grinding media in the front compartment is 60mm:50mm=3:1, the quantity ratio of the grinding media in the middle compartment is 50mm:40mm=2:1, and the quantity ratio of the grinding media in the rear compartment is 30mm:20mm:10m m=1:2:3, and at the front end of the spiral cutter conveying system, a grinding aid (sodium polyacrylate: polyethylene glycol mass ratio = 4:1, sodium polyacrylate molecular weight 1200~1500, polyethylene glycol molecular weight 3600~3800) accounting for 7‰ of the mass of the coarse silicon powder is added by diluting with water (water: grinding aid mass ratio = 7:1). The ground silicon powder is classified and enters the raw powder silo. The product is tested by BT-9300ST laser particle size analyzer. 50 2.12μm, D 97 The particle size was 5.92 μm, and the raw silicon micropowder was obtained;

[0074] The raw silicon micropowder is conveyed into the 1# high-speed mixer through a spiral cutter for high-speed stirring. The material temperature of the high-speed mixer is 75℃, the mixing is 10min, the high-speed mixer speed is 450r / min, and polyamide wax (melting point is 70℃, particle size D) accounting for 5‰ of the raw silicon micropowder mass is added. 50 5.0 μm), continue mixing for 20 minutes, then enter the 1# cold mixer for cold mixing for 5 minutes, the cold mixer speed is 250 r / min, and the first modified silicon powder is obtained;

[0075] The material in the cold mixer is transported to the 2# high speed mixer through the pipeline, and fumed silica (specific surface area of ​​400m2) accounting for 4% of the mass of the first modified silicon powder is added. 2 / g, primary particle size <7 nm), high-speed mixing for 15 minutes, high-speed mixer speed of 700 r / min, material temperature of 45 ° C, the mixed material is conveyed into the 3# high-speed mixer through a spiral cutter with an electric heating function (temperature of 65 ° C), and the second modifier (γ-methacryloxypropyltrimethoxysilane: catechol mass ratio = 4:1) accounting for 2.5% of the total mass of the mixed material is added at the front end of the conveying system by solvent dilution (ethanol: second modifier mass ratio = 3:1). The material is mixed at high speed in the 3# high-speed mixer for 25 minutes, the high-speed mixer speed is 700 r / min, and the material temperature is 95 ° C. After the mixing is completed, the material enters the 2# cold mixer for cooling treatment, the cold mixing time is 8 minutes, the cold mixer speed is 250 r / min, and the modified matte silica powder is sieved.

[0076] Example 3

[0077] Select natural crystalline quartz ore with a silicon dioxide content of ≥99%, and after cleaning, drying, crushing with jaw crusher and hammer crushing, obtain quartz particles with a diameter of 10-35mm, which are conveyed by spiral cutter into the European version mill model MTW145G for primary grinding to obtain D 50 15.21μm, D 97The 69.24μm coarse silicon micropowder is conveyed by a spiral cutter into a three-compartment ball mill with a specification of 3.2m*13m (the volume ratio of the front compartment: middle compartment: rear compartment of the three-compartment ball mill is 1:1:3). The grinding medium filling rate is 65%, the quantity ratio of the grinding media in the front compartment is 60mm:50mm=3:1, the quantity ratio of the grinding media in the middle compartment is 50mm:40mm=2:1, and the quantity ratio of the grinding media in the rear compartment is 30mm:20mm:10mm =1:2:3, at the front end of the spiral cutter conveying system, a grinding aid (sodium polyacrylate: polyethylene glycol mass ratio = 5:1, sodium polyacrylate molecular weight 1600-1800, polyethylene glycol molecular weight 3800-4000) accounting for 8‰ of the mass of the coarse silicon powder is added by diluting with water (water: grinding aid mass ratio = 8:1). The ground silicon powder is classified and enters the final raw powder silo. The product is tested by BT-9300ST laser particle size analyzer. 50 2.04μm, D 97 The particle size is 5.84 μm, and the raw silicon micropowder is obtained;

[0078] The raw silicon micropowder is conveyed into the 1# high-speed mixer through a spiral cutter for high-speed stirring. The material temperature of the high-speed mixer is 80℃, the mixing is 10min, the high-speed mixer speed is 500r / min, and polyamide wax (melting point is 70℃, particle size D) accounting for 6‰ of the raw silicon micropowder mass is added. 50 5.0 μm), continue mixing for 20 minutes, then enter the 1# cold mixer for cold mixing for 5 minutes, the cold mixer speed is 300 r / min, and the first modified silicon powder is obtained;

[0079] The material in the cold mixer is transported to the 2# high speed mixer through the pipeline, and fumed silica (specific surface area of ​​400m2) accounting for 5% of the mass of the first modified silicon powder is added. 2 / g, primary particle size <7 nm), high-speed mixing for 20 minutes, high-speed mixer speed of 800 r / min, material temperature of 50 ° C, the mixed material is conveyed into the 3# high-speed mixer through a spiral cutter with an electric heating function (temperature of 70 ° C), and the second modifier (γ-methacryloxypropyltrimethoxysilane: catechol mass ratio = 4:1) accounting for 3% of the mixed material is added at the front end of the conveying system by solvent dilution (ethanol: second modifier mass ratio = 3:1). The material is mixed at high speed for 25 minutes in the 3# high-speed mixer, the high-speed mixer speed is 800 r / min, and the material temperature is 100 ° C. After the mixing is completed, the material enters the 2# cold mixer for cooling treatment, the cold mixing time is 10 minutes, the cold mixer speed is 300 r / min, and the modified matte silica powder is sieved.

[0080] Comparative Example 1

[0081] Conventional silicon micropowder (GS-8000 produced by Jiangxi Guangyuan Chemical Co., Ltd.) was used as comparative example 1.

[0082] Test Example 1

[0083] The modified matte silicon powder prepared in Examples 1 to 3 and the conventional silicon powder product in Comparative Example 1 were tested for relevant indicators according to SJ / T 10675-2002. The results are shown in Table 1.

[0084] Table 1 Detection indexes of silicon micropowder

[0085]

[0086]

[0087] As shown in Table 1, the modified matte silica powder prepared in Examples 1-3 of the present invention has a significantly better specific surface area than conventional silica powder. Furthermore, after undergoing special surface treatment, the product has lower oil absorption than conventional silica powder. This effectively balances matte and leveling properties when used in downstream matte paints. Furthermore, compared to fumed silica, the modified matte silica powder prepared in Examples 1-3 of the present invention can balance the rheological properties and various mechanical properties of the paint film, demonstrating greater versatility.

[0088] Test Example 2

[0089] The modified matte silica powder prepared in Examples 1 to 3 was applied to matte paint (formula see Table 2), and compared with the conventional silica powder in Comparative Example 1. The test was carried out according to GB / T 23999-2009 standard. The test results are shown in Table 3.

[0090] Table 2 Matte paint formula (parts)

[0091]

[0092]

[0093] Table 3 Matt paint properties using different silica powders

[0094]

[0095] As can be seen from Table 3, when the modified matte silica powder products prepared in Examples 1 to 3 of the present invention are used in matte paint, the gloss of the paint film is significantly lower than that of conventional silica powder products, and no additional auxiliary matting agent is required. The standard of matte paint (gloss <20%) is fully met, and the adhesion of the product is better than that of conventional silica powder products, reaching level 0, and the rheological properties are good. In addition, the hardness, water resistance and alcohol resistance of the paint film also meet the product performance requirements.

[0096] 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 principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing modified matte silicon powder, characterized in that: The following steps are involved: The crystalline quartz ore is crushed, and the obtained quartz particles are first ground to obtain coarse silicon micropowder; The coarse silicon micropowder powder is mixed with a grinding aid, subjected to a second grinding, and then classified to obtain raw silicon micropowder powder; The silicon micropowder raw powder is subjected to a first mixing process, then mixed with a first modifier, subjected to a first modification process, and then subjected to a first cold mixing process to obtain a first modified silicon micropowder; After performing a second mixing of the first modified silicon micropowder and fumed silica, the resulting mixture is mixed with a second modifier and subjected to a second modification treatment to obtain a second modified silicon micropowder; performing a second cold mixing on the second modified silica powder to obtain modified matte silica powder; The first modifier is polyamide wax; The second modifier is γ-methacryloxypropyltrimethoxysilane and catechol.

2. The preparation method according to claim 1, characterized in that The diameter of the quartz particles is 10 to 35 mm; the particle size D of the coarse silicon powder is 50 14~16μm, D 97 It is 69~74μm.

3. The preparation method according to claim 1, characterized in that The grinding aids are sodium polyacrylate and polyethylene glycol, the mass ratio of the sodium polyacrylate to the polyethylene glycol is 3-5:1; the molecular weight of the sodium polyacrylate is 1000-2000; the molecular weight of the polyethylene glycol is 3500-4000.

4. The preparation method according to claim 3, characterized in that The grinding aid is added by diluting with water; the mass ratio of the water to the grinding aid is 6 to 8:1; the mass of the grinding aid accounts for 6 to 8‰ of the mass of the coarse silicon micropowder.

5. The preparation method according to claim 4, characterized in that The conditions for the second grinding include: the grinding media are ceramic balls of different diameters, the grinding media filling rate is 55-65%, the diameters of the grinding media in the front chamber are 60 mm and 50 mm, and the ratio of the 60 mm diameter ceramic balls to the 50 mm diameter ceramic balls is 2-3:1, the diameters of the grinding media in the middle chamber are 50 mm and 40 mm, and the ratio of the 50 mm diameter ceramic balls to the 40 mm diameter ceramic balls is 1-2:1, and the diameters of the grinding media in the rear chamber are 30 mm, 20 mm, and 10 mm, and the ratio of the 30 mm diameter ceramic balls to the 20 mm diameter ceramic balls to the 10 mm diameter ceramic balls is 1:1-2:2-3; The D of the silicon micropowder raw powder 50 2.0~2.2μm, D 97 5.8~6.0μm.

6. The preparation method according to claim 1, characterized in that The material temperature of the first mixing material is 70-80°C, the mixing time is 10-20min, and the rotation speed is 400-500r / min; the particle size D of the first modifier is 50 The particle size of the first modifier is 5.0 μm, the mass of the first modifier is 4 to 6‰ of the total mass of the silicon micropowder original powder; the time of the first modification treatment is 20 to 30 minutes; the time of the first cold mixing is 5 to 10 minutes, and the speed of the cold mixer is 200 to 300 r / min.

7. The preparation method according to claim 1, characterized in that The fumed silica is hydrophilic fumed silica, and the specific surface area of ​​the fumed silica is 400 m 2 / g, primary particle size <7nm; the mass of the fumed silica is 3-5% of the mass of the first modified silicon powder; the second mixing time is 10-20min, the high mixer speed is 600-800r / min, and the material temperature is 40-50℃.

8. The preparation method according to claim 1, characterized in that The mass ratio of γ-methacryloxypropyltrimethoxysilane to catechol is 3 to 4:1, and the mass of the second modifier is 2 to 3% of the total mass of the mixed material obtained by the second mixing; the material temperature of the second modification treatment is 90 to 100°C, the time is 20 to 30 minutes, and the high mixer speed is 600 to 800 r / min; the second cold mixing time is 5 to 10 minutes, and the cold mixer speed is 200 to 300 r / min.

9. Modified matte silica powder prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the modified matte silica powder according to claim 9 in matte paint.

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