WO2022233032A1

WO2022233032A1 - Method for preparing composite pigment and filler for coating by using silica fume

Info

Publication number: WO2022233032A1
Application number: PCT/CN2021/092153
Authority: WO
Inventors: 尚志新; 马洪才; 王晨宁; 郭昊; 张梅; 任冬寅
Original assignee: 德州学院
Priority date: 2021-05-07
Filing date: 2021-05-07
Publication date: 2022-11-10
Also published as: CN115103882A

Abstract

Embodiments of the present invention provide a method for preparing a composite pigment and filler for a coating by using silica fume. The method comprises: grading and scattering silica fume to obtain silica fume fine powder; physically modifying and granulating the silica fume fine powder to obtain a silica fume-based composite pigment and filler; and chemically modifying and granulating the silica fume-based composite pigment and filler to obtain a silica fume-based modified composite pigment and filler.

Description

Method for preparing composite pigment and filler for coating by utilizing silica fume

technical field

The invention belongs to the field of green resource utilization of industrial solid waste, and in particular relates to a method for preparing composite pigments and fillers for coatings by using silica fume.

Background technique

Currently, carbon black is the most widely used colorant (pigment) in the coatings field and is often used to produce black or gray coatings. However, the composition, density, particle size, hydrophilicity and other physical and chemical properties of carbon black are quite different from commonly used inorganic fillers (such as calcium carbonate, barium sulfate, calcined kaolin, talc, wollastonite, etc.) Delamination leads to floating and blooming of the paint, which in turn affects the storage stability of the paint. Carbon black has a large specific surface area and high oil absorption value, and it is easy to absorb a large amount of solvents and additives, causing problems such as thickening, thickening and whitening of oil-based coatings after storage. At present, although titanium dioxide-based white composite pigments and fillers are prepared by physical coating or chemical coating, due to the difference in properties of carbon black and inorganic fillers, it is difficult to obtain the corresponding composite pigments and fillers, and there is no black composite pigment yet. related reports on fillers.

Silica fume, also known as micro _- silica fume, is a spherical particulate dust formed in the flue during the process of smelting metal silicon _- based ferrosilicon alloys. O ₃ , CaO, Fe ₂ O ₃ , MgO, K ₂ O, Na ₂ O, carbon residue, etc. Its bulk density is 100-250kg/m ³ , and its particle size is mostly concentrated between 0.5-10 μm, which belongs to micro-nano particles. For every 3 tons of metallic silicon or 5 tons of ferrosilicon produced, 1 ton of silica fume is produced. In 2020, the output of silica fume in China will reach 2 million tons. At present, silica fume is mostly used in concrete, cement, refractory materials, metallurgy and other fields with low product added value, but there is basically no market for silica fume with silica content lower than 85%. Although purification by calcination, acid method, wet method or flocculation method can improve the purity of silica fume, the purification process is complicated, energy consumption is high, and it is easy to cause environmental pollution.

Therefore, how to find a method for realizing the green and high-value utilization of silica fume, especially low-grade silica fume, has become an urgent problem to be solved in the silica fume industry.

SUMMARY OF THE INVENTION

In view of the problems existing in the comprehensive utilization of black pigments and silica fume in the above-mentioned existing coatings, the present invention provides a method for preparing composite pigments and fillers for coatings by utilizing silica fume.

According to one aspect of the present invention, there is provided a method for preparing composite pigments and fillers for coatings by utilizing silica fume, the method comprising:

The silica fume is classified and dispersed to obtain fine silica fume powder;

Physical modification and granulation of silica fume fine powder to obtain composite pigments and fillers based on silica fume;

The silica fume-based composite pigments and fillers are chemically modified and granulated to obtain the silica fume-based modified composite pigments and fillers.

It can be seen from the above that the production processes involved in the method of the present invention are all purely physical processes, and do not involve processes such as strong acid and alkali, high pressure, etc. The production process is safe, green, and environmentally friendly, without the discharge of three wastes, and is suitable for different types of silica fume. Sex is higher. The composite pigment and filler produced by the method of the invention has uniform dispersion, good affinity with resin and excellent coloring effect, and can be widely used in the fields of paint, water paint and powder coating. The technical solution of the present invention solves the problems in the coating industry, and at the same time, truly realizes the green and high value-added utilization of silica fume.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention, which are very important in the art. For those of ordinary skill, other drawings can also be obtained from these drawings without creative labor. in:

FIG. 1 is a flow chart of a method for preparing a composite pigment and filler for coatings by using silica fume according to an embodiment of the present invention.

Detailed ways

In order to make the above objects, features and advantages of the present invention more clearly understood, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

In the embodiment of the present invention, the main component of silica fume is silicon dioxide, which is calcined at high temperature during the formation process, and has the characteristics of stable physicochemical properties, high temperature resistance, acid and alkali corrosion resistance, and the like. In the production process, the silica in silica fume is mostly condensed into balls with carbon residue as the nucleus, thus forming a tight package for the carbon residue. Therefore, silica fume has the potential to produce composite pigments and fillers for coatings.

The method of the invention can prepare composite pigments and fillers (that is, the composite pigments and fillers have the functions of both pigments and fillers) through a suitable production process according to the characteristics of silica fume, which not only solves the problems in the coating industry, but also realizes the improvement of silica fume. Green high-value utilization.

Referring to FIG. 1, an embodiment of the present invention provides a method for preparing composite pigments and fillers for coatings by utilizing silica fume, the method includes three processes of dispersing processing, physical modification and chemical modification:

(1) Dispersing and classifying processing includes classifying and dispersing processes, and preferably may also include drying processes. The drying is to use drying equipment to dry the water content of the silica fume to less than 1%. The classification is to use classification equipment to classify and remove the coarse particles in the dispersed silica fume according to the fineness requirements. The dispersing is to deaggregate the agglomerated silica fume particles using a dispersing device.

(2) Physical modification treatment: Mix a certain amount of physical modifier with the graded silica fume under the action of a small amount of adhesion aid and mechanochemistry (preferably mixed uniformly and tightly combined). By granulating the physically modified ultrafine silica fume, composite pigments and fillers can be obtained, which can be used for water-based paints, paints or powder coatings. The granulation is to select suitable granulation equipment to granulate the silica fume, so as to achieve the purpose of increasing the bulk density and facilitating transportation.

(3) Chemical modification treatment: use modification equipment, select the appropriate modifier and dosage, chemically modify the physically modified silica fume under certain conditions, and use granulation equipment to treat the chemically modified silica fume. Silica fume is granulated to obtain modified composite pigments and fillers, which can be used in water-based paints, paints or powder coatings.

The purpose of conducting and classifying and dispersing the silica fume (including the drying process) is to reduce the moisture and fineness of the silica fume. The step of drying the silica fume raw material is performed by drying equipment to make the moisture content of the silica fume raw material less than 1%, and the drying equipment includes a fluidized bed dryer, a dispersing drying pulverizer, a rotary dryer and a drum drying Any one of the machines or any combination thereof, the temperature range of the drying step is 80-300°C, preferably 150°C. In addition, the dried silica fume is classified to remove large particles in the silica fume and control the particle size of the silica fume. The classification is completed by a multi-rotor or single-rotor centrifugal classifier; the particle size of the silica fume particles after the classification is between 800-12500 mesh, preferably 8000 mesh or 10000 mesh. Further, the classified silica fume is dispersed to achieve depolymerization and improve the dispersibility of the silica fume. The dispersing equipment includes any one of a honeycomb mill, a vortex mill, a bar-cutting dispersing machine, a three-roll modifier, a dispersing drying pulverizer, and an air-flow mill, or any combination thereof.

The silica fume is physically modified and granulated after the step of grading and dispersing, so as to obtain a composite pigment and filler with controllable color, excellent anticorrosion performance and stable coloration. The physical modification is completed in the cavity of the dispersing equipment, and the granulation is completed in the silica fume encryption tank under the action of compressed air. The particle size of the particles after granulation is greater than 0.1mm, and the bulk density is greater than 250kg. /m ³ . The physical modification is to feed the physical modifier, the adhesive auxiliary and the ultra-finely processed materials into the dispersing machine to be dispersed and evenly mixed; the physical modifier includes red red, strontium chrome yellow, zinc Chrome yellow, barium chrome yellow, calcium chrome yellow, phosphate, phosphomolybdate, aluminum dihydrogen tripolyphosphate, zinc molybdate, zinc borate, mica iron oxide, titanium dioxide, nano-zinc oxide, graphite, ultramarine blue, phthalocyanine A mixture of any one or more of blue, barium sulfate, iron red, iron black, barium sulfate, etc.; the mass fraction of the physical modifier is 0%-30% of the mass of the silica fume powder; The adhesion assistant is any one of sodium silicate, potassium silicate, bis-silane coupling agent, etc. or any combination thereof; the mass fraction of the adhesion assistant is 0% of the powder quality of silica fume. %-5%.

After the physical modification step, the silica fume is chemically modified and granulated to obtain modified composite pigments and fillers. The step of chemical modification is performed by modification equipment. The modification equipment includes any one or any combination of a three-roll modifier, a high-speed mixer and a tower modifier, and the modifier used in the surface modification is a silane coupling agent, an aluminate Any one of coupling agent, titanate coupling agent, rare earth coupling agent, fatty acid and its salt, polyalcohols, higher alcohols, ammonium polyacrylate, or any combination thereof; the amount of the modifier It is 0.01-25% (eg 10% or 15%) of the mass of the silica fume powder; the temperature range of the surface modification is 50-300°C (eg 200°C).

Additionally, the coating is a powder coating, a water-based coating or a paint.

Several specific examples are provided below to describe in detail each step of the method of the present invention. Obviously, the technical solution of the present invention is not limited to the limitations of the examples provided below.

Example 1

The raw material of silica fume from a factory in Kangbashi, Inner Mongolia, has a water content of 0.5% and its main chemical composition is shown in Table 1. In this embodiment, the adopted processing technology includes four steps of classification, dispersing, physical modification and chemical modification. The specific preparation process parameters are as follows: firstly, the silica fume is classified with a single-rotor centrifugal classifier at a speed of 1900 rpm, and then the classified material and strontium chrome yellow with a mass fraction of 1% are fed into the honeycomb mill to complete the dispersing and After physical modification, the composite pigment and filler A1 was obtained after granulation; finally, a high-speed mixer was used for some materials after ultra-fine processing, and the silane coupling agent (KH560) with a mass fraction of 2% was used as the modifier, and the temperature was continuously maintained at 120 ° C. After stirring for 15min, the modified composite pigment and filler A2 was obtained, and its particle size distribution was shown in Table 2.

Table 1 Chemical composition of materials

Table 2 Particle size distribution of different fillers

Example 2

The main chemical composition of silica fume from a factory in Taiyuan, Shanxi Province is 1.5% and its main chemical composition is shown in Table 3. In this embodiment, the adopted processing techniques are drying, classification, dispersing, physical modification and chemical modification. The specific preparation process parameters are as follows: first, the silica fume is dried to a moisture content of 0.5% with a fluidized bed dryer, the inlet temperature of the dryer is 210°C, and the outlet temperature is 90°C. The silica fume is then classified by a single-rotor centrifugal classifier at a speed of 1900 rpm, and then the classified material, 0.7% strontium chrome yellow and 0.5% iron phosphate are fed into the cutting rod beating Dispersing machine, complete dispersing and physical modification, and obtain composite pigment and filler B1 after granulation; DL411), directly sprayed into the three-roll modifier through the atomizing nozzle, chemically modified at 87 ° C, and granulated to obtain the modified composite pigment and filler B2, whose particle size distribution is shown in Table 4.

Table 3 Chemical composition of materials

Table 4 Particle size distribution of different fillers

Example 3

Using the modified composite pigments and fillers A2 and B2 prepared in Example 1 and Example 2, a comparison experiment was carried out in gray anti-corrosion paint with a commonly used pigment and filler system (carbon black + titanium dioxide + calcium carbonate, control example). The formula and performance comparison are shown in Table 5:

Table 5 Gray anti-corrosion paint formulation, paint preparation process and performance comparison

Example 4

Using the composite pigments and fillers A1 and B1 prepared in Example 1 and Example 2, a comparison experiment was carried out with the commonly used pigment and filler systems (carbon black + titanium dioxide + calcium carbonate, control example) in the gray anti-corrosion water-based paint. Coating formulations and performance comparisons are shown in Table 6:

Table 6 Gray anti-corrosion water-based paint formulation, paint preparation process and performance comparison

Example 5

Using the modified composite pigments and fillers A2 and B2 prepared in Example 1 and Example 2, a comparison experiment was carried out with the commonly used pigment and filler systems (carbon black + titanium dioxide + calcium carbonate, control example) in gray powder coatings. The formula and performance comparison are shown in Table 7:

Table 7 Powder coating formulation, coating preparation process and performance comparison

Through comparative analysis, it can be seen that the composite pigment and filler prepared by the method of the present invention can play the dual role of pigment and filler, and can significantly improve the affinity and dispersibility with organic resins. Compared with the commonly used pigment and filler systems, the method of the present invention can not only reduce the production cost of the coating, but also can significantly improve the storage, corrosion resistance, weather resistance and other properties of the coating. The method of the invention has significant environmental protection significance and economic benefits, and has broad market prospects.

Although some embodiments of the present general inventive concept have been shown and described, those of ordinary skill in the art will understand that The scope is defined by the claims and their equivalents.

Claims

A method for preparing composite pigments and fillers for coatings by utilizing silica fume, the method comprising:

The silica fume is classified and dispersed to obtain fine silica fume powder;

Physical modification and granulation of silica fume fine powder to obtain composite pigments and fillers based on silica fume;

The silica fume-based composite pigments and fillers are chemically modified and granulated to obtain the silica fume-based modified composite pigments and fillers.
The method of claim 1, wherein,

Before the grading and dispersing treatment, the method further includes drying the silica fume, and the drying treatment includes drying the water content of the silica fume to less than 1% by using a drying device.
The method according to claim 1 or 2, wherein,

The classification and disintegration treatment includes classifying the particles in the silica fume by using classification equipment to obtain silica fume particles with a particle size of 800-12500 mesh, and deaggregating the agglomerated silica fume particles using the disintegrating device.
The method according to any one of claims 3, wherein,

The classification equipment includes a multi-rotor or single-rotor centrifugal classifier, which includes any one of a honeycomb mill, a vortex mill, a bar-cutting machine, a three-roller modifier, a powder-drying pulverizer, and an air-flow mill. species or any combination of them
The method of any one of claims 1-4, wherein,

The physical modification and granulation treatment include mixing a physical modifier and a binding aid with the silica fume particles left after the classification treatment, and then subjecting the physically modified silica fume particles to a granulation treatment to obtain a composite pigment. filler.
The method of claim 5, wherein,

The physical modification step is carried out in the cavity of the disintegrating device.
The method of claim 5, wherein,

The granulation treatment step is performed in a silica fume densification tank under the action of compressed air, the particle size of the granulated particles is greater than 0.1 mm, and the bulk density is greater than 250 kg/m 3 .
The method according to any one of claims 5-7, wherein,

The physical modifiers include red red, strontium chrome yellow, zinc chrome yellow, barium chrome yellow, calcium chrome yellow, phosphate, phosphomolybdate, aluminum dihydrogen tripolyphosphate, zinc molybdate, zinc borate, mica oxide. A mixture of any one or more of iron, titanium dioxide, nano-zinc oxide, graphite, ultramarine blue, phthalocyanine blue, barium sulfate, iron red, iron black, and barium sulfate; the mass fraction of the physical modifier is 0%-30% of the powder mass of silica fume.
The method of claim 8, wherein,

The adhesion assistant includes any one of sodium silicate, potassium silicate, bissilane coupling agent or any combination thereof; the mass fraction of the adhesion assistant is 0% of the mass of the silica fume powder- 5%.
The method of any one of claims 1-9, wherein,

The step of chemical modification is performed by modification equipment.
The method of claim 10, wherein,

The modification equipment includes any one or any combination of a three-roll modifier, a high-speed mixer and a tower modifier, and the modifier used in the surface modification is a silane coupling agent, an aluminate Any one of coupling agents, titanate coupling agents, rare earth coupling agents, fatty acids and their salts, polyalcohols, higher alcohols, and ammonium polyacrylate, or any combination thereof.
The method of claim 11, wherein,

The dosage of the modifier is 0.01-25% of the mass of the silica fume powder.
The method of claim 11, wherein,

The temperature range for the surface modification is 50-300°C.
The method of any one of claims 1-13, wherein,

The coating is powder coating, water-based coating or paint.