Hardening composite filler as well as preparation method and application thereof

Abstract

The invention provides a hardening composite filler as well as a preparation method and application thereof, and belongs to the technical field of powder coating hardening. Through reasonable filler compounding and surface modification processes, abrasion of traditional high-hardness filler to equipment in the powder coating production process is effectively avoided. When the obtained hardening composite filler is applied to the high-hardness powder coating, the glossiness, the appearance and the replacement frequency of a screw rod of the high-hardness powder coating are obviously superior to those of a traditional hardening filler, the remarkable performance advantages are achieved, and the defects of the traditional high-hardness powder coating hardening mode are overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of powder coating hardening, and particularly relates to a hardening composite filler, a preparation method thereof, and an application thereof. Background Art

[0002] Powder coatings are solid powder synthetic resin coatings composed of solid resins, pigments, fillers, and additives. They have the characteristics of no solvent pollution, 100% film formation, and low energy consumption, and are widely used in fields such as building profiles, construction machinery, fire fighting equipment, and medium density fiberboards. In building metal profiles, if the hardness of the powder coating sprayed on the surface is insufficient, it is easy to cause scratches and bumps on the surface during the handling, assembly, and use of the profiles, seriously affecting the appearance of the product. Therefore, higher requirements are put forward for the hardness of the powder coating.

[0003] There are generally three main ways to harden powder coatings: 1. By selecting polyester resins with high hydroxyl values to increase the crosslinking density of the coating film; 2. By adding high-hardness fillers to increase the hardness of the paint film; 3. By adding wax powder to reduce the friction coefficient to improve the scratch resistance of the paint film. However, all three methods have certain limitations. Increasing the hardness of the paint film by increasing the crosslinking density will result in a significant decrease in the mechanical properties of the paint film as the crosslinking density increases. Therefore, generally only a hardness of about 3H can be obtained; adding high-hardness fillers can make the hardness of the paint film reach above 6H. However, due to the extremely high wear of high-hardness fillers on equipment during the production process, the replacement frequency of the screw is high, and due to equipment wear, the magnetic substances in the product are relatively high, which will also seriously affect the downstream use; while improving the hardness of the paint film by adding wax powder, if the addition amount and the adjustment or selection of the wax powder type are not appropriate, it is easy to cause fogging on the surface of the coating film, resulting in serious loss of gloss.

[0004] Therefore, on the premise of trying to avoid side effects, how to effectively improve the hardness of the coating film of powder coatings has become an urgent problem to be solved in the industry. Summary of the Invention

[0005] The purpose of the present invention is to provide a hardening composite filler, a preparation method thereof, and an application thereof, which are used to solve the technical problem that traditional high-hardness fillers wear equipment during the production process of powder coatings in the prior art.

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

[0007] The present invention provides a preparation method of a hardening composite filler, comprising the following steps:

[0008] Step 1), grinding and classifying natural quartz ore in sequence to obtain silica powder raw powder, and then mixing it with modifier 1 diluted with water and performing modification treatment to obtain modified silica powder;

[0009] Step 2): Grind and classify wollastonite concentrate successively to obtain wollastonite raw powder, then mix it with modifier 2 diluted with water and carry out modification treatment to obtain modified wollastonite powder;

[0010] Step 3): Grind and classify white talc successively to obtain talc powder raw powder, then mix it with modifier 3 diluted with water and carry out modification treatment to obtain modified talc powder;

[0011] Step 4): Mix modified silica powder, modified wollastonite powder and modified talc powder, add modifier 4 for secondary modification treatment, and then carry out cold mixing to obtain the hardening composite filler;

[0012] The modifier 1 is a silane coupling agent, the modifier 2 is a silane oligomer, the modifier 3 is a mixture of polyether and silane, and the modifier 4 is polytetrafluoroethylene modified polyethylene wax;

[0013] In step 4), the mass ratio of the modified silica powder, the modified wollastonite powder and the modified talc powder is 6-8:1-2:1.

[0014] Further, in step 1), the silica content in the natural quartz ore is ≥99%, and the grinding is carried out in a fully ceramic-lined ball mill with ceramic grinding media;

[0015] In step 2), the silica content in the wollastonite concentrate is ≥51%, and the grinding is carried out in a jet mill lined with ceramic;

[0016] In step 3), the silica content in the white talc is ≥60%, and the grinding is carried out in a jet mill lined with ceramic.

[0017] Further, in step 1), the modifier 1 includes N-2-aminoethyl-3-aminopropylmethyldiethoxysilane and 3-divinyltriaminopropylmethyldimethoxysilane, and the mass ratio of N-2-aminoethyl-3-aminopropylmethyldiethoxysilane to 3-divinyltriaminopropylmethyldimethoxysilane is 1-3:1;

[0018] The mass ratio of the modifier 1 to water is 1:5-7;

[0019] The addition amount of the modifier 1 is 1-3‰ of the mass of the silica powder raw powder;

[0020] The modification treatment is carried out under stirring, the stirring speed is 800-1000 r / min, the modification treatment temperature is 90-100 °C, and the modification treatment time is 20-30 min;

[0021] The particle size of the silica powder raw powder is 11.5-12 μm.

[0022] Further, in step 2), the modifier 2 includes a vinyl silane hydrolysis oligomer and a 3-aminopropyltrialkoxysilane hydrolysis oligomer, and the mass ratio of the vinyl silane hydrolysis oligomer to the 3-aminopropyltrialkoxysilane hydrolysis oligomer is 1:2 to 4;

[0023] The mass ratio of the modifier 2 to water is 1:3 to 5;

[0024] The addition amount of the modifier 2 is 4 to 6‰ of the mass of the wollastonite original powder;

[0025] The modification treatment is carried out under stirring, the stirring speed is 800 to 1000 r / min, the modification treatment temperature is 100 to 110 °C, and the modification treatment time is 20 to 30 min;

[0026] The particle size of the wollastonite original powder is 9.0 to 10.0 μm.

[0027] Further, in step 3), the modifier 3 includes a polyether-modified silicone leveling agent and 3-acetoxypropyltrimethoxysilane, and the mass ratio of the polyether-modified silicone leveling agent to 3-acetoxypropyltrimethoxysilane is 1:1 to 2;

[0028] The mass ratio of the modifier 3 to water is 1:5 to 6;

[0029] The addition amount of the modifier 3 is 2 to 4‰ of the mass of the talc original powder;

[0030] The modification treatment is carried out under stirring, the stirring speed is 800 to 1000 r / min, the modification treatment temperature is 110 to 120 °C, and the modification treatment time is 20 to 30 min;

[0031] The particle size of the talc original powder is 7.0 to 8.0 μm.

[0032] Further, in step 4), the number average molecular weight of the modifier 4 is 2000 to 4000;

[0033] The addition method of the modifier 4 is spray addition after melting.

[0034] Further, in step 4), the secondary modification treatment is carried out under stirring, the stirring speed is 800 to 1000 r / min, the secondary modification treatment temperature is 110 to 120 °C, and the secondary modification treatment time is 20 to 30 min;

[0035] The addition amount of the modifier 4 is 3 to 5‰ of the sum of the masses of the modified silica powder, the modified wollastonite powder and the modified talc powder.

[0036] Further, in step 4), the cold mixing is carried out in a cold mixer, the rotation speed of the cold mixing is 200-400 r / min, and the time of the cold mixing is 5-10 min.

[0037] The present invention provides a hardening composite filler prepared by the above preparation method.

[0038] The present invention also provides an application of the above hardening composite filler in the preparation of powder coatings.

[0039] Advantages of the present invention:

[0040] The present invention uses three kinds of powders, namely silica powder, wollastonite and talc powder, for compounding, and prepares a hardening composite filler through a reasonable filler compounding ratio and surface modification treatment. When it is applied in powder coatings, it can significantly improve the hardness of the paint film, reduce the wear of the equipment, and at the same time avoid the defects of fogging and loss of gloss of the paint film easily caused by traditional use of wax powder for hardening, and solves the problems existing in the development of current high-hardness powder coating products;

[0041] The present invention uses talc powder with a SiO2 content ≥ 60% and an aspect ratio > 60:1 as an auxiliary lubricant to compound with the other two kinds of powders. When applied in powder coatings, it improves the extrusion performance during the production process, reduces the wear of the screw, improves the smoothness of the paint film, reduces the friction coefficient, and further improves the scratch resistance of the paint film;

[0042] In the hardening composite filler of the present invention, the acicular wollastonite with a high aspect ratio is more conducive to filling in the gaps between granular silica powder particles, improving the compactness of particle packing, thereby improving the compactness of the paint film, making the flatness of the paint film higher, and indirectly improving the scratch resistance. Description of the drawings

[0043] Figure 1 It is a process flow chart for the preparation of the hardening composite filler of the present invention. Detailed implementation manners

[0044] The present invention provides a method for preparing a hardening composite filler, comprising the following steps:

[0045] Step 1), grinding and classifying natural quartz ore in sequence to obtain silica powder raw powder, and then mixing it with modifier 1 diluted with water and carrying out modification treatment to obtain modified silica powder;

[0046] Step 2), grinding and classifying wollastonite concentrate in sequence to obtain wollastonite powder raw powder, and then mixing it with modifier 2 diluted with water and carrying out modification treatment to obtain modified wollastonite powder;

[0047] Step 3): Grind and classify talc in sequence to obtain raw talc powder, then mix it with modifier 3 diluted with water and carry out modification treatment to obtain modified talc powder;

[0048] Step 4): Mix modified silica powder, modified wollastonite powder and modified talc powder, add modifier 4 for secondary modification treatment, and then carry out cold mixing to obtain the hardening composite filler;

[0049] The modifier 1 is a silane coupling agent, the modifier 2 is a silane oligomer, the modifier 3 is a mixture of polyether and silane, and the modifier 4 is a polytetrafluoroethylene modified polyethylene wax;

[0050] In step 4), the mass ratio of the modified silica powder, modified wollastonite powder and modified talc powder is 6-8:1-2:1.

[0051] In the present invention, the mass ratio of the modified silica powder, modified wollastonite powder and modified talc powder is 6-8:1-2:1, preferably 7:1.5:1. Among them, since the silica powder has the highest hardness (Mohs hardness is 7), it is the main hardening body. The acicular wollastonite is used as a filler to fill between the silica powder particles to improve the flatness of the paint film and indirectly improve the scratch resistance. The talc powder is used as an auxiliary lubricant to improve the fluidity, reduce the damage to the screw during the production process, and at the same time reduce the friction coefficient of the coating to improve the scratch resistance.

[0052] In the present invention, in step 1), the silica content in the natural quartz ore is preferably ≥99%, and the grinding is carried out in a fully ceramic-lined ball mill, and the grinding medium is ceramic.

[0053] In the present invention, the ball mill is a fully ceramic-lined ball mill, the grinding medium is a compound of ceramic balls with different proportions, and the classification wheel is a ceramic classification wheel, which can effectively avoid the defect of high magnetic substance content caused by equipment wear.

[0054] In the present invention, a 1.83*7.2m ball mill is used to carry out ultrafine grinding of natural quartz ore, and silica powder raw powder with D50 of 4.5-5.0μm and D97 of 11.5-12μm is obtained through air classification.

[0055] In the present invention, in step 2), the silica content in the wollastonite concentrate is preferably ≥51%, and the grinding is carried out in a jet mill lined with ceramic.

[0056] In the present invention, a jet mill is used to carry out ultrafine grinding and classification of wollastonite concentrate to obtain wollastonite raw powder with D50 of 2.0-2.5μm and D97 of 7.0-8.0μm.

[0057] In the present invention, the SiO2 content of the wollastonite concentrate is ≥51%, and the aspect ratio is greater than 12:1. The acicular wollastonite with a high aspect ratio is more conducive to filling the gaps between granular silica powder particles, improving the compactness of particle packing, thereby enhancing the compactness of the paint film, making the flatness of the paint film higher, and indirectly improving the scratch resistance performance.

[0058] In the present invention, in step 3), the silica content in the white talc is preferably ≥60%, and the grinding is carried out in a jet mill lined with ceramic.

[0059] In the present invention, the white talc is ultrafinely ground and classified by a jet mill to obtain a raw talc powder with D50 of 2.0 - 2.5 μm and D97 of 7.0 - 8.0 μm.

[0060] In the present invention, the white talc is a white talc ore with SiO2 content ≥60%. The produced talc powder has an aspect ratio of thickness to diameter >60:1. The high-purity talc powder is soft and slippery, has a layered structure, and the interlayer force is weak, so relative sliding is likely to occur between layers, and it has certain lubricating properties. Among the three composite powders, talc powder is used as an auxiliary lubricant, which can improve the extrusion performance during the production process. At the same time, due to its low Mohs hardness (Mohs hardness is 1), the damage to the screw is extremely low. When applied to the final product, the presence of talc powder can also reduce the friction coefficient and further improve the scratch resistance performance of the paint film.

[0061] In the present invention, the jet mills are all jet mills lined with ceramic, which can reduce the magnetic substance content of the product to the greatest extent, and at the same time can maintain the acicular structure of wollastonite and the flaky structure of talc powder to the greatest extent.

[0062] In the present invention, the raw silica powder, raw wollastonite powder and raw talc powder are respectively fed into high-speed mixers 1, 2 and 3 by a spiral auger conveying system for modification.

[0063] In the present invention, modifier 1, modifier 2 and modifier 3 are all added in the form of water dilution at the front end of the spiral auger conveying system.

[0064] In the present invention, the modified silica powder, modified wollastonite powder and modified talc powder are respectively transported through pipelines and fed into bins 1, 2 and 3 for standby.

[0065] In the present invention, in step 1), the modifier 1 is preferably N-2-aminoethyl-3-aminopropylmethyldiethoxysilane and 3-diethylenetriaminepropylmethyldimethoxysilane; the mass ratio of N-2-aminoethyl-3-aminopropylmethyldiethoxysilane to 3-diethylenetriaminepropylmethyldimethoxysilane is 1 - 3:1, preferably 2:1;

[0066] The mass ratio of the modifier 1 to water is 1:5 - 7, preferably 1:6;

[0067] The addition amount of the modifier 1 is 1 - 3‰ of the mass of the original silica powder, preferably 2‰;

[0068] The modification treatment is carried out under stirring, the stirring speed is 800 - 1000 r / min, preferably 850 - 950 r / min, and further preferably 900 r / min; the temperature of the modification treatment is 90 - 100 °C, preferably 95 °C; the time of the modification treatment is 20 - 30 min, preferably 22 - 28 min, and further preferably 25 min;

[0069] The particle size of the original silica powder is preferably 11.5 - 12 μm.

[0070] In the present invention, in step 2), the modifier 2 is preferably a vinylsilane hydrolysis oligomer and a 3-aminopropyltrialkoxysilane hydrolysis oligomer; the mass ratio of the vinylsilane hydrolysis oligomer to the 3-aminopropyltrialkoxysilane hydrolysis oligomer is 1:2 - 4, preferably 1:3;

[0071] The mass ratio of the modifier 2 to water is 1:3 - 5, preferably 1:4;

[0072] The addition amount of the modifier 2 is 4 - 6‰ of the mass of the original wollastonite powder, preferably 5‰;

[0073] The modification treatment is carried out under stirring, the stirring speed is 800 - 1000 r / min, preferably 850 - 950 r / min, and further preferably 900 r / min; the temperature of the modification treatment is 100 - 110 °C, preferably 105 °C, and the time of the modification treatment is 20 - 30 min, preferably 22 - 28 min, and further preferably 25 min;

[0074] The particle size of the original wollastonite powder is 9.0 - 10.0 μm, preferably 9.5 μm.

[0075] In the present invention, in step 3), the modifier 3 is preferably a polyether-modified silicone leveling agent and 3-acetoxypropyltrimethoxysilane, and the mass ratio of the polyether-modified silicone leveling agent to 3-acetoxypropyltrimethoxysilane is 1:1 - 2, preferably 1:1;

[0076] The mass ratio of the modifier 3 to water is 1:5 - 6, preferably 1:5.5;

[0077] The addition amount of the modifier 3 is 2 - 4‰ of the mass of the original talc powder, preferably 3‰;

[0078] The modification treatment is carried out under stirring, the stirring speed is 800 - 1000 r / min, preferably 850 - 950 r / min, and more preferably 900 r / min; the temperature of the modification treatment is 110 - 120 °C, preferably 105 °C; the time of the modification treatment is 20 - 30 min, preferably 22 - 28 min, and more preferably 25 min;

[0079] The particle size of the original talc powder is 7.0 - 8.0 μm, preferably 7.5 μm.

[0080] In the present invention, in step 4), the number-average molecular weight of the modifier 4 is 2000 - 4000, preferably 2500 - 3500;

[0081] The addition method of the modifier 4 is spray addition after melting.

[0082] In the present invention, the modifier 4 is polytetrafluoroethylene-modified polyethylene wax. As the main lubricating and hardening aid, its dropping melting point is 110 °C and D50 is 5 μm.

[0083] In the present invention, in step 4), the modified silica powder, modified wollastonite powder and modified talc powder are transported into a horizontal mixer through pipelines, and the mixing time is 10 - 15 min, preferably 13 min, and then subsequent secondary modification treatment is carried out after obtaining the composite powder.

[0084] In the present invention, in step 4), the secondary modification treatment is carried out under stirring, the stirring speed is 800 - 1000 r / min, preferably 850 - 950 r / min, and more preferably 900 r / min; the temperature of the secondary modification treatment is 110 - 120 °C, preferably 105 °C; the time of the secondary modification treatment is 20 - 30 min, preferably 22 - 28 min, and more preferably 25 min;

[0085] The addition amount of the modifier 4 is 3 - 5‰ of the sum of the masses of the modified silica powder, modified wollastonite powder and modified talc powder, preferably 4‰.

[0086] In the present invention, in step 4), the cold mixing is carried out in a cold mixer, the cold mixing speed is 200 - 400 r / min, preferably 300 r / min; the cold mixing time is 5 - 10 min, preferably 7 min.

[0087] The present invention provides a hardening composite filler prepared by the above preparation method.

[0088] The present invention also provides an application of the above hardening composite filler in the preparation of powder coatings.

[0089] The technical solution provided by the present invention will be described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0090] Example 1

[0091] The natural quartz ore with a silica content > 99% is ground in a ball mill and then subjected to air classification to obtain a raw silicon micropowder with D50 of 4.72 μm and D97 of 11.86 μm. It enters the high-speed mixer 1 through a spiral auger conveying system for modification treatment. At the front end of the spiral auger conveying system, modifier 1 (the mass ratio of N-2-aminoethyl-3-aminopropylmethyldiethoxysilane and 3-divinyltriaminopropylmethyldimethoxysilane is 1:1) accounting for 1‰ of the dry powder mass is added in the form of water dilution (the dilution ratio is the mass ratio of modifier 1 to water is 1:5). Then, the material temperature is maintained at 95°C, and the modification treatment is carried out for 20 min under the condition of a rotation speed of 800 r / min to obtain the modified silicon micropowder, which is transported into the storage bin 1 through a pipeline for standby;

[0092] The wollastonite concentrate with a silica content > 51% is subjected to ultrafine grinding and classification by a jet mill to obtain a raw wollastonite powder with D50 of 3.68 μm and D97 of 9.72 μm. Then, it enters the high-speed mixer 2 through a spiral auger conveying system for modification treatment. At the front end of the spiral auger conveying system, modifier 2 (the mass ratio of vinylsilane hydrolysis oligomer and 3-aminopropyltrialkoxysilane hydrolysis oligomer is 1:2) accounting for 5‰ of the dry powder mass is added in the form of water dilution (the dilution ratio is the mass ratio of modifier 2 to water is 1:3). Then, the material temperature is maintained at 100°C, and the modification treatment is carried out for 20 min under the condition of a rotation speed of 600 r / min to obtain the modified wollastonite powder, which is transported into the storage bin 2 through a pipeline for standby;

[0093] The white talc with a silica content > 60% is subjected to ultrafine grinding and classification by a jet mill to obtain a raw talc powder with D50 of 2.34 μm and D97 of 7.65 μm. Then, it enters the high-speed mixer 3 through a spiral auger conveying system for modification treatment. At the front end of the spiral auger conveying system, modifier 3 (the mass ratio of polyether-modified organosilicon leveling agent and 3-acetoxypropyltrimethoxysilane is 1:1) accounting for 3‰ of the dry powder mass is added in the form of water dilution (the dilution ratio is the mass ratio of modifier 3 to water is 1:5). The material temperature is maintained at 110°C, and the modification treatment is carried out for 20 min under the condition of a rotation speed of 800 r / min. After the modification is completed, the modified talc powder is transported into the storage bin 3 through a pipeline for standby;

[0094] The modified silica powder, modified wollastonite powder and modified talc powder are fed into a horizontal mixer in a mass ratio of 6:1:1 and mixed for 10 min. The obtained composite powder is conveyed into a high-speed mixer 4 by a spiral auger for secondary modification treatment. Polytetrafluoroethylene-modified polyethylene wax accounting for 3‰ of the dry powder mass is added at the front end of the spiral auger conveying system. The material temperature is maintained at 110°C, and the modification treatment is carried out for 20 min under the condition of a rotation speed of 800 r / min. Then, the composite powder is sent into a cold mixer for cold mixing. The rotation speed of the cold mixer is 200 r / min, and the cold mixing time is 5 min. The material after cold mixing is sent into the finished product bin through pneumatic conveying, sieved, tested, and then packaged.

[0095] Example 2

[0096] The natural quartz ore with a silica content > 99% is ground in a ball mill and air-classified to obtain the original silica powder with D50 of 4.72 μm and D97 of 11.86 μm. It enters a high-speed mixer 1 through a spiral auger conveying system for modification treatment. Modifier 1 (the mass ratio of N-2-aminoethyl-3-aminopropylmethyldiethoxysilane to 3-divinyltriaminopropylmethyldimethoxysilane is 2:1) accounting for 2‰ of the dry powder mass is added at the front end of the spiral auger conveying system in a water dilution manner (the dilution ratio of modifier 1 to water is 1:6). Then, the material temperature is maintained at 95°C, and the modification treatment is carried out for 25 min under the condition of a rotation speed of 900 r / min to obtain the modified silica powder, which is conveyed into bin 1 through a pipeline for standby;

[0097] The wollastonite concentrate with a silica content > 51% is ultrafinely ground and classified by a jet mill to obtain the original wollastonite powder with D50 of 3.68 μm and D97 of 9.72 μm. Then, it enters a high-speed mixer 2 through a spiral auger conveying system for modification treatment. Modifier 2 (the mass ratio of vinylsilane hydrolysis oligomer to 3-aminopropyltrialkoxysilane hydrolysis oligomer is 1:3) accounting for 5‰ of the dry powder mass is added at the front end of the spiral auger conveying system in a water dilution manner (the dilution ratio of modifier 2 to water is 1:4). Then, the material temperature is maintained at 105°C, and the modification treatment is carried out for 25 min under the condition of a rotation speed of 700 r / min to obtain the modified wollastonite powder, which is conveyed into bin 2 through a pipeline for standby;

[0098] The white talc with a silica content > 60% is ultrafinely ground and classified by a jet mill to obtain the original talc powder with D50 of 2.34 μm and D97 of 7.65 μm. Then it is fed into a high-speed mixer 3 through a spiral auger conveying system for modification treatment. At the front end of the spiral auger conveying system, modifier 3 (the mass ratio of polyether-modified silicone leveling agent and 3-acetoxypropyltrimethoxysilane is 1:2) accounting for 3‰ of the dry powder mass is added in the form of water dilution (the dilution ratio is the mass ratio of modifier 3 to water is 1:5). Keep the material temperature at 115°C and carry out the modification treatment for 25 minutes under the condition of a rotation speed of 900 r / min. After the modification is completed, the modified talc powder is transported through a pipeline and stored in a bin 3 for standby;

[0099] The modified silica powder, modified wollastonite powder and modified talc powder are fed into a horizontal mixer in a mass ratio of 7:2:1 and mixed for 13 minutes. The obtained composite powder is fed into a high-speed mixer 4 through a spiral auger conveying system for secondary modification treatment. At the front end of the spiral auger conveying system, polytetrafluoroethylene-modified polyethylene wax accounting for 4‰ of the dry powder mass is added. Keep the material temperature at 115°C and carry out the modification treatment for 25 minutes under the condition of a rotation speed of 900 r / min. Then the composite powder is sent into a cold mixer for cold mixing. The rotation speed of the cold mixer is 300 r / min and the cold mixing time is 8 minutes. After the cold mixing is completed, the material is pneumatically conveyed into the finished product bin, sieved, detected and packaged.

[0100] Example 3

[0101] The natural quartz ore with a silica content > 99% is ground in a ball mill and classified by air flow to obtain the original silica powder with D50 of 4.72 μm and D97 of 11.86 μm. It is fed into a high-speed mixer 1 through a spiral auger conveying system for modification treatment. At the front end of the spiral auger conveying system, modifier 1 (the mass ratio of N-2-aminoethyl-3-aminopropylmethyldiethoxysilane and 3-diethylenetriaminepropylmethyldimethoxysilane is 3:1) accounting for 3‰ of the dry powder mass is added in the form of water dilution (the dilution ratio is the mass ratio of modifier 1 to water is 1:7). Then keep the material temperature at 100°C and carry out the modification treatment for 30 minutes under the condition of a rotation speed of 1000 r / min to obtain the modified silica powder, which is transported through a pipeline and stored in a bin 1 for standby;

[0102] The wollastonite concentrate with silica content > 51% is ultrafinely ground and classified by a jet mill to obtain the original wollastonite powder with D50 of 3.68 μm and D97 of 9.72 μm. Then it is fed into the high-speed mixer 2 through a spiral auger conveying system for modification treatment. At the front end of the spiral auger conveying system, modifier 2 (vinyl silane hydrolysis oligomer and 3-aminopropyltrialkoxysilane hydrolysis oligomer with a mass ratio of 1:4) accounting for 6‰ of the dry powder mass is added in a water dilution manner (the dilution ratio is the mass ratio of modifier 2 to water of 1:5). After that, the material temperature is maintained at 110°C, and the modification treatment is carried out for 30 min under the condition of a rotation speed of 800 r / min to obtain the modified wollastonite powder, which is then transported through a pipeline into the storage bin 2 for standby;

[0103] The white talc with silica content > 60% is ultrafinely ground and classified by a jet mill to obtain the original talc powder with D50 of 2.34 μm and D97 of 7.65 μm. Then it is fed into the high-speed mixer 3 through a spiral auger conveying system for modification treatment. At the front end of the spiral auger conveying system, modifier 3 (polyether-modified organosilicon leveling agent and 3-acetoxypropyltrimethoxysilane with a mass ratio of 1:2) accounting for 4‰ of the dry powder mass is added in a water dilution manner (the dilution ratio is the mass ratio of modifier 3 to water of 1:6). The material temperature is maintained at 115°C, and the modification treatment is carried out for 30 min under the condition of a rotation speed of 1000 r / min. After the modification is completed, the modified talc powder is transported through a pipeline into the storage bin 3 for standby;

[0104] The modified silica powder, modified wollastonite powder and modified talc powder are transported into a horizontal mixer according to the mass ratio of 8:2:1 and mixed for 15 min. The obtained composite powder is then fed into the high-speed mixer 4 through a spiral auger for secondary modification treatment. At the front end of the spiral auger conveying system, polytetrafluoroethylene-modified polyethylene wax accounting for 5‰ of the dry powder mass is added. The material temperature is maintained at 120°C, and the modification treatment is carried out for 30 min under the condition of a rotation speed of 1000 r / min. Then the composite powder is sent into a cold mixer for cold mixing. The rotation speed of the cold mixer is 400 r / min, and the cold mixing time is 10 min. After the cold mixing is completed, the material is pneumatically conveyed into the finished product storage bin, screened, tested, and then packaged.

[0105] The hardening composite filler products obtained in Examples 1 to 3 are respectively tested for relevant indicators according to GB / T 23774-2009, GBT 5211.15-2014, GB / T 6284-2006 and GB / T 19077-2016. The relevant indicators are shown in Table 1:

[0106] Table 1 Detection indicators and results of the composite filler products obtained in Examples 1 to 3

[0107] Detection Index Example 1 Example 2 Example 3 Whiteness / ° 94.3 94.4 94.5 Oil Absorption / mL / 100g 32 31 30 Moisture / % 0.17 0.16 0.16 D50 / μm 4.63 4.65 4.64 D97 / μm 11.52 11.53 11.55

[0108] The hardening composite powders obtained in Examples 1 to 3 and traditional hardening fillers were respectively applied to high-hardness powder coatings and tested according to relevant standards. By mass parts, the formulation of the high-hardness powder coating is shown in Table 2.

[0109] Table 2 Formulation of High-Hardness Powder Coating

[0110]

[0111] Table 3 Test Results of High-Hardness Powder Coatings Obtained in Application Examples 1 to 4

[0112]

[0113]

[0114] As can be seen from the above examples, the present invention provides a hardening composite filler and its preparation method and application. As can be seen from Table 3, compared with traditional hardening fillers, when the hardness is the same at 8H, the gloss, appearance and screw replacement frequency of the high-hardness powder coatings prepared in Examples 1 to 3 are significantly better than those of traditional hardening fillers, having significant performance advantages.

[0115] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a hardening composite filler, characterized in that, It includes the following steps: Step 1): Grind and classify natural quartz ore successively to obtain raw silica powder, then mix it with modifier 1 diluted with water and carry out modification treatment to obtain modified silica powder; Step 2): Grind and classify wollastonite concentrate successively to obtain raw wollastonite powder, then mix it with modifier 2 diluted with water and carry out modification treatment to obtain modified wollastonite powder; Step 3): Grind and classify white talc successively to obtain raw talc powder, then mix it with modifier 3 diluted with water and carry out modification treatment to obtain modified talc powder; Step 4): Mix the modified silica powder, modified wollastonite powder and modified talc powder, add modifier 4 for secondary modification treatment, and then carry out cold mixing to obtain the hardening composite filler; The modifier 1 is a silane coupling agent, the modifier 2 is a silane oligomer, the modifier 3 is a mixture of polyether and silane, and the modifier 4 is a polytetrafluoroethylene-modified polyethylene wax; In step 4), the mass ratio of the modified silica powder, modified wollastonite powder and modified talc powder is 6-8:1-2:

1.

2. The preparation method of a hardening composite filler according to claim 1, characterized in that, In step 1), the silica content in the natural quartz ore is ≥99%, the grinding is carried out in a fully ceramic-lined ball mill, and the grinding medium is ceramic; In step 2), the silica content in the wollastonite concentrate is ≥51%, and the grinding is carried out in a jet mill lined with ceramic; In step 3), the silica content in the white talc is ≥60%, and the grinding is carried out in a jet mill lined with ceramic.

3. The preparation method of a hardening composite filler according to claim 1 or 2, characterized in that, In step 1), the modifier 1 includes N-2-aminoethyl-3-aminopropylmethyldiethoxysilane and 3-diethylenetriaminepropylmethyldimethoxysilane, and the mass ratio of N-2-aminoethyl-3-aminopropylmethyldiethoxysilane to 3-diethylenetriaminepropylmethyldimethoxysilane is 1-3:1; The mass ratio of the modifier 1 to water is 1:5-7; The addition amount of the modifier 1 is 1-3‰ of the mass of the raw silica powder; The modification treatment is carried out under stirring, the stirring speed is 800-1000 r / min, the temperature of the modification treatment is 90-100 °C, and the time of the modification treatment is 20-30 min; The particle size of the raw silica powder is 11.5-12 μm.

4. The preparation method of a hardening composite filler according to claim 3, characterized in that, In step 2), the modifier 2 includes vinylsilane hydrolysis oligomer and 3-aminopropyltrialkoxysilane hydrolysis oligomer, and the mass ratio of vinylsilane hydrolysis oligomer to 3-aminopropyltrialkoxysilane hydrolysis oligomer is 1:2-4; The mass ratio of the modifier 2 to water is 1:3-5; The addition amount of the modifier 2 is 4-6‰ of the mass of the raw wollastonite powder; The modification treatment is carried out under stirring, the stirring speed is 800-1000 r / min, the temperature of the modification treatment is 100-110 °C, and the time of the modification treatment is 20-30 min; The particle size of the raw wollastonite powder is 9.0-10.0 μm.

5. The preparation method of a hardening composite filler according to claim 1 or 2 or 4, characterized in that, In step 3), the modifier 3 includes a polyether-modified silicone leveling agent and 3-acetoxypropyltrimethoxysilane, and the mass ratio of the polyether-modified silicone leveling agent to 3-acetoxypropyltrimethoxysilane is 1:1-2; The mass ratio of the modifier 3 to water is 1:5 - 6; The addition amount of the modifier 3 is 2 - 4‰ of the mass of the original talc powder; The modification treatment is carried out under stirring, the stirring speed is 800 - 1000 r / min, the temperature of the modification treatment is 110 - 120 °C, and the time of the modification treatment is 20 - 30 min; The particle size of the original talc powder is 7.0 - 8.0 μm.

6. The preparation method of a hardening composite filler according to claim 5, characterized in that, In step 4), the number-average molecular weight of the modifier 4 is 2000 - 4000; The addition method of the modifier 4 is spray addition after melting.

7. The preparation method of a hardening composite filler according to claim 6, characterized in that In step 4), the secondary modification treatment is carried out under stirring, the stirring speed is 800 - 1000 r / min, the temperature of the secondary modification treatment is 110 - 120 °C, and the time of the secondary modification treatment is 20 - 30 min; The addition amount of the modifier 4 is 3 - 5‰ of the sum of the masses of the modified silica powder, the modified wollastonite powder and the modified talc powder.

8. The preparation method of a hardening composite filler according to claim 1 or 6 or 7, characterized in that, In step 4), the cold mixing is carried out in a cold mixer, the rotation speed of the cold mixing is 200 - 400 r / min, and the time of the cold mixing is 5 - 10 min.

9. The hardening composite filler prepared by the preparation method according to any one of claims 1 - 8.

10. The application of the hardening composite filler according to claim 9 in the preparation of powder coatings.

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