Method for preparing active nano-kaolin powder

Abstract

Disclosed is a method for preparing active nano-kaolin powder, comprising: drying kaolin concentrate; mixing the dried kaolin concentrate with chemical additives, wherein the chemical additives comprise an intercalating agent and a surfactant, and are mixed in a mass ratio of kaolin concentrate : intercalating agent : surfactant = 100 : 5-60 : 1-10; milling the mixed kaolin and chemical additives in a ball mill for 5-10 min to achieve thorough and uniform mixing, then transferring to ultrasonic or microwave treatment to carry out an intercalation reaction for 1-3 hours; transferring the resulting intercalated slurry to a sand mill for ultrafine grinding for 10-60 min; washing the ultrafinely ground slurry and then performing surface modification; subjecting the modified material to centrifugal dewatering, drying, and deagglomeration; the powder obtained after deagglomeration is the active nano-kaolin powder product. By performing wet surface modification on nano-kaolin, the present invention can effectively reduce agglomeration of nano-particles during the drying process and improve the dispersibility of nano-kaolin.

Description

A method for preparing active nano-kaolin powder Technical Field

[0001] This invention relates to the field of kaolin preparation technology, specifically to a method for preparing active nano-kaolin powder. Background Technology

[0002] Kaolin products are widely used in paints, coatings, papermaking, rubber, plastics, cables, ceramics, enamel, refractory materials, textiles, cement, automobiles, chemicals, environmental protection, agriculture and other fields due to their high whiteness, good crystal form, large porosity, low density, good chemical stability and insulation, and strong hiding power.

[0003] my country produces a wide variety of kaolin products, but high-grade products account for less than 20%, mainly used in papermaking, high-grade paints, and the automotive industry, as well as partially replacing titanium dioxide. A large amount of high-grade kaolin still needs to be imported annually. Nano-kaolin is a two-dimensional nanoparticle material with a sheet thickness of less than 100 nm, a sheet thickness of 20–100 nm, a particle size of 300–500 nm, and a typical hexagonal flake microstructure. Unlike nano-spherical carbon black and silica, nano-kaolin, when used in rubber products, not only exhibits excellent reinforcing properties in conventional properties such as mechanical properties and durability, but also demonstrates unique advantages in enhancing specific properties such as flame retardancy and airtightness. Nano-kaolin possesses many characteristics such as fine particle size, high whiteness, large specific surface area, strong adsorption capacity, and stable chemical properties. It is widely used as a thickener in special paper coatings, paints and coatings, pigments, catalyst carriers, moisturizers in high-end cosmetics, and additives in high-grade inks. In rubber and plastics, it can replace silica and some carbon black as a reinforcing agent.

[0004] The main preparation processes for nano-kaolin include mechanical abrasion, graded sedimentation, and intercalation. Among these, intercalation is currently the most effective method for preparing nano-kaolin. Nano-kaolin particles are fine, have a large surface area, and high activity, making them prone to agglomeration during dehydration and drying.

[0005] Therefore, this invention provides a method for preparing active nano-kaolin powder, which uses an intercalation-ultrafine grinding-surface modification-centrifugal dehydration-drying-deagglomeration process to prepare active nano-kaolin powder. By performing wet surface modification on nano-kaolin, the agglomeration of nanoparticles during the drying process can be effectively reduced, and the dispersibility of nano-kaolin can be improved. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing active nano-kaolin powder. By performing wet surface modification on nano-kaolin, the agglomeration of nanoparticles during the drying process can be effectively reduced, and the dispersibility of nano-kaolin can be improved.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for preparing active nano-kaolin powder includes the following steps:

[0009] (1) Drying of raw materials: Drying the kaolin concentrate;

[0010] (2) The dried kaolin concentrate from step (1) is mixed with chemical additives, wherein the chemical additives include intercalating agents and surfactants, and are mixed in a mass ratio of kaolin concentrate: intercalating agent: surfactant = 100:5~60:1~10;

[0011] (3) The mixed kaolin and chemical additives are ground in a ball mill for 5-10 minutes to ensure thorough mixing, and then transferred to an ultrasonic or microwave incubator for intercalation reaction for 1-3 hours to obtain the intercalated slurry.

[0012] (4) The intercalated slurry is transferred to a sand mill for ultra-fine grinding for 10-60 minutes to obtain an ultra-fine ground slurry.

[0013] (5) The ultra-fine ground slurry is washed and then surface modified;

[0014] (6) The modified material is centrifuged, dehydrated, dried, and depolymerized;

[0015] (7) The powder after depolymerization is the active nano kaolin powder product.

[0016] Preferably, in step (1), the kaolin concentrate has a particle size of D90 less than 2 micrometers.

[0017] Preferably, in step (2), the intercalating agent is selected from one or more of potassium acetate, dimethyl sulfoxide, dimethylamide, thiourea and urea, and the surfactant is selected from one or more of hexadecyltrimethylammonium bromide, sodium dodecyl sulfonate, Tween 80 and Tween 40.

[0018] Preferably, in step (3), the temperature of the ultrasonic or microwave intercalation reaction is 50-100°C; and the concentration of the slurry after intercalation is 30%-70%.

[0019] Preferably, in step (4), the grinding media in the sand mill is 0.5-1mm zirconium balls, and the media filling rate is 50%.

[0020] Preferably, in step (5), the surface modifier is selected from one or more of stearic acid, silane, titanate, aluminate, and silicone oil, the modification temperature is 80-120°C, and the modification time is 10-60 min.

[0021] Preferably, in step (7), the active nano-kaolin powder product has a sheet thickness of 20-90 nm and a particle size of 200-500 nm.

[0022] Due to the application of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0023] 1. This invention uses an intercalation-ultrafine grinding-surface modification-centrifugal dehydration-drying-deagglomeration process to prepare active nano-kaolin powder. By performing wet surface modification on nano-kaolin, the agglomeration of nanoparticles during the drying process can be effectively reduced, and the dispersibility of nano-kaolin can be improved.

[0024] 2. The active nano-kaolin powder product of this invention can be used in composite materials such as rubber and plastics to reinforce and improve the flame retardant properties, airtightness and insulation properties of the materials, and can partially replace silica and carbon black.

[0025] 3. The present invention performs surface modification on the slurry after ultrafine grinding and washing, which can avoid or reduce the agglomeration of nano-kaolin particles during the drying process of the slurry, and obtain nano-kaolin powder with finer and more uniform particle size. At the same time, the modified powder can be directly used in rubber and plastic composite materials to increase compatibility with the matrix. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1

[0028] This embodiment provides a method for preparing active nano-kaolin powder, including the following steps:

[0029] (1) Drying of raw materials: The kaolin concentrate is dried to a particle size of D90 less than 2 micrometers;

[0030] (2) The dried kaolin concentrate from step (1) is mixed with chemical additives, wherein the chemical additives include intercalating agents and surfactants, and are mixed in a mass ratio of kaolin concentrate: intercalating agent: surfactant = 100:30:4; the intercalating agent is dimethyl sulfoxide and the surfactant is hexadecyltrimethylammonium bromide.

[0031] (3) The mixed kaolin and chemical additives are ground in a ball mill for 10 minutes to ensure thorough mixing, and then transferred to an ultrasonic intercalation reaction for 2 hours to obtain an intercalated slurry. The temperature of the ultrasonic intercalation reaction is 80°C, and the concentration of the intercalated slurry is 50%.

[0032] (4) The slurry after intercalation is transferred to a sand mill for ultrafine grinding for 50 minutes to obtain an ultrafine ground slurry. The sand milling media in the sand mill is 0.5-1 mm zirconium balls with a media filling rate of 50%.

[0033] (5) The slurry after ultrafine grinding is washed and then surface modified. The surface modifier is stearic acid, the modification temperature is 100℃, and the modification time is 30min.

[0034] (6) The modified material is centrifuged, dehydrated, dried, and depolymerized;

[0035] (7) The powder after depolymerization is the active nano kaolin powder product; the active nano kaolin powder product has a sheet thickness of 50-90 nm and a particle size of 200-500 nm.

[0036] Example 2

[0037] This embodiment provides a method for preparing active nano-kaolin powder, including the following steps:

[0038] (1) Drying of raw materials: The kaolin concentrate is dried to a particle size of D90 less than 2 micrometers;

[0039] (2) The dried kaolin concentrate from step (1) is mixed with chemical additives, wherein the chemical additives include intercalating agents and surfactants, and are mixed in a mass ratio of kaolin concentrate: intercalating agent: surfactant = 100:40:4; the intercalating agent is dimethylamide and the surfactant is hexadecyltrimethylammonium bromide.

[0040] (3) The mixed kaolin and chemical additives are ground in a ball mill for 10 minutes to ensure thorough mixing, and then transferred to an ultrasonic intercalation reaction for 3 hours to obtain an intercalated slurry. The temperature of the ultrasonic intercalation reaction is 80°C, and the concentration of the intercalated slurry is 50%.

[0041] (4) The slurry after intercalation is transferred to a sand mill for ultrafine grinding for 50 minutes to obtain an ultrafine ground slurry. The sand milling media in the sand mill is 0.5-1 mm zirconium balls with a media filling rate of 50%.

[0042] (5) The slurry after ultrafine grinding is washed and then surface modified. The surface modifier is silane, the modification temperature is 100℃, and the modification time is 30min.

[0043] (6) The modified material is centrifuged, dehydrated, dried, and depolymerized;

[0044] (7) The powder after depolymerization is the active nano kaolin powder product; the active nano kaolin powder product has a sheet thickness of 20-90 nm and a particle size of 200-500 nm.

[0045] Example 3

[0046] This embodiment provides a method for preparing active nano-kaolin powder, including the following steps:

[0047] (1) Drying of raw materials: The kaolin concentrate is dried to a particle size of D90 less than 2 micrometers;

[0048] (2) The dried kaolin concentrate from step (1) is mixed with chemical additives, wherein the chemical additives include intercalating agents and surfactants, and are mixed in a mass ratio of kaolin concentrate: intercalating agent: surfactant = 100:55:4; the intercalating agent is urea and the surfactant is sodium dodecyl sulfonate.

[0049] (3) The mixed kaolin and chemical additives are ground in a ball mill for 20 minutes to ensure thorough mixing, and then transferred to an ultrasonic intercalation reaction for 3 hours to obtain an intercalated slurry. The temperature of the ultrasonic intercalation reaction is 60°C, and the concentration of the intercalated slurry is 50%.

[0050] (4) The slurry after intercalation is transferred to a sand mill for ultrafine grinding for 60 minutes to obtain an ultrafine ground slurry. The sand milling media in the sand mill is 0.5-1 mm zirconium balls with a media filling rate of 50%.

[0051] (5) The slurry after ultrafine grinding is washed and then surface modified. The surface modifier is titanate, the modification temperature is 95℃, and the modification time is 25min.

[0052] (6) The modified material is centrifuged, dehydrated, dried, and depolymerized;

[0053] (7) The powder after depolymerization is the active nano kaolin powder product; the active nano kaolin powder product has a sheet thickness of 20-70 nm and a particle size of 300-500 nm.

[0054] Example 4

[0055] This embodiment provides a method for preparing active nano-kaolin powder, including the following steps:

[0056] (1) Drying of raw materials: The kaolin concentrate is dried to a particle size of D90 less than 2 micrometers;

[0057] (2) The dried kaolin concentrate from step (1) is mixed with chemical additives, wherein the chemical additives include intercalating agents and surfactants, and are mixed in a mass ratio of kaolin concentrate: intercalating agent: surfactant = 100:50:6; the intercalating agent is dimethyl sulfoxide and the surfactant is hexadecyltrimethylammonium bromide.

[0058] (3) The mixed kaolin and chemical additives are ground in a ball mill for 10 minutes to ensure thorough mixing, and then transferred to an ultrasonic intercalation reaction for 3 hours to obtain an intercalated slurry. The temperature of the ultrasonic intercalation reaction is 80°C, and the concentration of the intercalated slurry is 50%.

[0059] (4) The slurry after intercalation is transferred to a sand mill for ultrafine grinding for 60 minutes to obtain an ultrafine ground slurry. The sand milling media in the sand mill is 0.5-1 mm zirconium balls with a media filling rate of 50%.

[0060] (5) The slurry after ultrafine grinding is washed and then surface modified. The surface modifier is stearic acid, the modification temperature is 100℃, and the modification time is 25min.

[0061] (6) The modified material is centrifuged, dehydrated, dried, and depolymerized;

[0062] (7) The powder after depolymerization is the active nano kaolin powder product; the active nano kaolin powder product has a sheet thickness of 20-70 nm and a particle size of 200-500 nm.

[0063] Comparative Example 1

[0064] This comparative example was conducted based on Example 1 above. The difference from Example 1 is that the slurry after ultrafine grinding was not surface modified after washing. The remaining steps are the same as in Example 1. The resulting active nano-kaolin powder product has a sheet thickness of 70-100 nm and a particle size of 500-1000 nm.

[0065] Comparative Example 2

[0066] This comparative example is based on Example 1 above. The difference from Example 1 is that only a surfactant was added and no intercalating agent was added when the kaolin concentrate was mixed with the chemical additives. The remaining steps are the same as in Example 1. The resulting active nano kaolin powder product has a sheet thickness of 100-200 nm and a particle size of 500-1000 nm.

[0067] As can be seen from Example 1, Comparative Example 1, and Comparative Example 2, the active nano-kaolin powder product prepared according to the preparation method of the present invention has better thickness and particle size.

[0068] In summary, this invention employs an intercalation-ultrafine grinding-surface modification-centrifugal dehydration-drying-deagglomeration process to prepare active nano-kaolin powder. By performing wet surface modification on the nano-kaolin, the agglomeration of nanoparticles during drying is effectively reduced, improving the dispersibility of the nano-kaolin. The active nano-kaolin powder product of this invention can be used in composite materials such as rubber and plastics to reinforce and improve the flame retardant, airtight, and insulating properties of the materials, and can partially replace silica and carbon black. The surface modification of the slurry after ultrafine grinding and washing avoids or reduces the agglomeration of nano-kaolin particles during slurry drying, resulting in finer and more uniform nano-kaolin powder. Simultaneously, the modified powder can be directly used in rubber and plastic composite materials, increasing compatibility with the matrix.

[0069] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing activated nano-kaolin powder, characterized in that, Includes the following steps: (1) Drying of raw materials: Drying the kaolin concentrate; (2) The dried kaolin concentrate from step (1) is mixed with chemical additives, wherein the chemical additives include intercalating agents and surfactants, and are mixed in a mass ratio of kaolin concentrate: intercalating agent: surfactant = 100:5~60:1~10; (3) The mixed kaolin and chemical additives are ground in a ball mill for 5-10 minutes to ensure thorough mixing, and then transferred to an ultrasonic or microwave incubator for intercalation reaction for 1-3 hours to obtain the intercalated slurry. (4) The intercalated slurry is transferred to a sand mill for ultra-fine grinding for 10-60 minutes to obtain an ultra-fine ground slurry; (5) The ultra-fine ground slurry is washed and then surface modified; (6) The modified material is centrifuged, dehydrated, dried, and depolymerized; (7) The powder after depolymerization is the active nano kaolin powder product.

2. The method for preparing active nano-kaolin powder as described in claim 1, characterized in that, In step (1), the particle size of the kaolin concentrate is D90, which is less than 2 micrometers.

3. The method for preparing activated nano-kaolin powder as described in claim 1, characterized in that, In step (2), the intercalating agent is selected from one or more of potassium acetate, dimethyl sulfoxide, dimethylamide, thiourea and urea, and the surfactant is selected from one or more of hexadecyltrimethylammonium bromide, sodium dodecyl sulfonate, Tween 80 and Tween 40.

4. The method for preparing activated nano-kaolin powder as described in claim 1, characterized in that, In step (3), the temperature of the ultrasonic or microwave intercalation reaction is 50-100°C; the concentration of the slurry after intercalation is 30%-70%.

5. The method for preparing active nano-kaolin powder as described in claim 1, characterized in that, In step (4), the grinding media in the sand mill are 0.5-1mm zirconium balls, and the media filling rate is 50%.

6. The method for preparing active nano-kaolin powder as described in claim 1, characterized in that, In step (5), the surface modifier is selected from one or more of stearic acid, silane, titanate, aluminate and silicone oil, the modification temperature is 80-120℃ and the modification time is 10-60min.

7. The method for preparing active nano-kaolin powder as described in claim 1, characterized in that, In step (7), the thickness of the active nano-kaolin powder product is 20-90 nm and the particle size is 200-500 nm.