Sanding-free natural superfine barium sulfate powder as well as preparation method and application thereof

Abstract

The invention provides sanding-free natural superfine barium sulfate powder as well as a preparation method and application thereof, and belongs to the technical field of inorganic chemical filler preparation. The preparation method comprises the following steps: sequentially carrying out grinding, ball milling and two-time grading on barite particles to prepare barite raw powder; and carrying out surface modification treatment on the barite raw powder, and cooling to obtain the sanding-free natural superfine barium sulfate powder. Wherein a composite modifier is added during surface modification treatment, and the composite modifier is prepared by compounding a stearic acid emulsion and a tetrakis-neo-alkoxy bis (didecyl phosphorous acid acyloxy) titanate coupling agent. The composite modifier modifies the barite raw powder, not only reduces the oil absorption value of the superfine barium sulfate, but also reduces the surface energy of the product through the bonding effect, improves the dispersity of the product and the adhesive force with downstream resin, and can achieve the use fineness required by the product through high-speed dispersion when being applied to the water-based industrial paint. And the production efficiency is effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of inorganic chemical filler preparation, and in particular to a sand-free natural ultrafine barium sulfate powder and a preparation method and application thereof. Background Art

[0002] Water-based industrial paint mainly uses water as a diluent and does not require the addition of organic solvents as solvents. It is a new type of environmentally friendly anti-corrosion paint that is different from oil-based industrial paint. The application range of water-based industrial paint is extremely wide, and it can be seen everywhere in bridges, steel structures, ships, electromechanical, steel, etc. With the increasing attention paid to environmental protection, water-based industrial paint has been rapidly developed because of its energy-saving and environmental protection, and will not cause harm and pollution to the human body and the environment. It is the future development direction of the industrial coating industry and one of the alternative products of traditional oil-based industrial paint.

[0003] However, in the production process, oil-based industrial paints are generally ground and dispersed with resin, so the dispersion requirements for fillers are relatively low; while in the pulping process of water-based industrial paints, in order to reduce the wastewater discharge of car washes, and because the main film-forming material is emulsion, the high molecular chain segments of the emulsion dispersed by high-speed grinding are at risk of being interrupted, thereby affecting the performance of the product, it generally tends to be ground without resin, so the dispersion requirements for fillers are relatively high. Precipitated barium sulfate has become the most important mineral filler material in water-based industrial paints due to its significant advantages such as low oil absorption, high particle density, high whiteness, acid and alkali resistance, etc. However, since precipitated barium sulfate is prepared by chemical synthesis, there are many uncontrollable factors in the production process, so there are defects such as poor stability between batches and large surface energy of the product. In water-based industrial paints, it is usually impossible to achieve the required fineness of use through high-speed dispersion, and it needs to be dispersed to the required fineness after sand grinding. In addition, the quality of precipitated barium sulfate from different manufacturers is uneven, and the dispersion varies greatly, which greatly affects production efficiency and automated production.

[0004] The surface energy of natural barium sulfate is lower than that of precipitated barium sulfate, and because it is produced by a short process flow, the stability between product batches is better than that of precipitated barium sulfate, but the untreated raw powder has poor compatibility with resin, and the dispersibility cannot meet the use requirements of water-based industrial paint. In the prior art, generally, hydrophilic dispersants such as polycarboxylates and sulfonates are used, or lipophilic and hydrophobic dispersants of polyoxyethylene ethers are used to improve the dispersibility of the product, but no matter which one, there are respective disadvantages (hydrophilicity is too strong, water resistance is not good, lipophilicity is too strong, compatibility is not good), which is not suitable for use in the system. Therefore, a kind of natural ultra-fine barium sulfate powder without sand grinding and its preparation method are studied, and it is of great significance when it is applied to water-based industrial paint. Summary of the invention

[0005] The purpose of the present invention is to provide a natural ultrafine barium sulfate powder free of sand grinding and a preparation method and application thereof, so as to solve the problem in the prior art that natural barium sulfate and precipitated barium sulfate have poor compatibility with resin and cannot meet the requirements for dispersibility.

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

[0007] The present invention provides a method for preparing natural ultrafine barium sulfate powder without sand grinding, comprising the following steps:

[0008] (1) grinding, ball milling, and twice classifying the barite particles in sequence to obtain barite raw powder;

[0009] (2) subjecting the raw barite powder to surface modification treatment and cooling to obtain natural ultrafine barium sulfate powder without sand grinding;

[0010] A composite modifier is added during the surface modification treatment; the composite modifier is prepared by compounding stearic acid emulsion and tetraneoalkoxy bis (didecyl phosphite acyloxy) titanate coupling agent.

[0011] Preferably, in the step (1), the particle size of the barite particles is 10 to 50 mm; and a composite ball milling aid is added during the ball milling, wherein the composite ball milling aid is compounded from an acrylic block copolymer dispersant and a non-ionic dispersant.

[0012] Preferably, the mass ratio of the acrylic block copolymer dispersant to the nonionic dispersant is 4:1-3.

[0013] Preferably, the addition amount of the composite ball milling aid is 4-8‰ based on the mass of the barite coarse powder obtained by grinding; the composite ball milling aid is diluted with water before being added, and the dilution ratio is 6-8:1.

[0014] Preferably, in the step (1), the two classifications include a primary classification and a secondary classification, which are performed in series using a 4-head classification wheel and a 6-head classification wheel, wherein the 4-head classification wheel is a straight-edge classification wheel with a classifier frequency of 36 to 38 Hz, and the 6-head classification wheel is a bevel-edge classification wheel with a classifier frequency of 64 to 66 Hz.

[0015] Preferably, the mass ratio of the stearic acid emulsion to the tetraneoalkoxybis(didecylphosphite)titanate coupling agent is 1:2-4.

[0016] Preferably, the addition amount of the composite modifier is 5-8‰ based on the mass of the barite raw powder; the composite modifier is diluted with water before being added, and the dilution ratio is 1:1-3.

[0017] Preferably, the surface modification treatment is carried out at a temperature of 100 to 110° C. for 10 to 20 minutes; and the cooling time is 20 to 30 minutes.

[0018] The present invention also provides natural superfine barium sulfate powder without sand grinding, which is prepared by the method for preparing the natural superfine barium sulfate powder without sand grinding.

[0019] The present invention also provides an application of the above-mentioned sand-free natural ultrafine barium sulfate powder in coatings.

[0020] Beneficial effects of the present invention:

[0021] The invention uses barite particles obtained by crushing barite concentrate as raw materials, and prepares sand-free natural ultrafine barium sulfate powder with narrow particle size distribution through grinding, ball milling and two classifications.

[0022] The present invention uses stearic acid emulsion and tetraneoalkoxybis(didecylphosphite acyloxy)titanate coupling agent as composite modifiers to perform surface modification on barite raw powder. The stearic acid emulsion mainly reduces the oil absorption value of ultrafine barium sulfate, and the titanate coupling agent mainly reduces the surface energy of the product through bonding, thereby improving the dispersibility of the product and the adhesion to the downstream resin.

[0023] The invention prepares natural ultrafine barium sulfate powder without sand grinding, and applies the powder to water-based industrial paint to achieve the fineness required by the product through high-speed dispersion, thereby effectively improving the production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a process flow chart for preparing natural ultrafine barium sulfate powder without sand grinding. DETAILED DESCRIPTION

[0025] The present invention provides a method for preparing natural ultrafine barium sulfate powder without sand grinding, comprising the following steps:

[0026] (1) grinding, ball milling, and twice classifying the barite particles in sequence to obtain barite raw powder;

[0027] (2) subjecting the raw barite powder to surface modification treatment and cooling to obtain natural ultrafine barium sulfate powder without sand grinding;

[0028] A composite modifier is added during the surface modification treatment; the composite modifier is prepared by compounding stearic acid emulsion and tetraneoalkoxy bis (didecyl phosphite acyloxy) titanate coupling agent.

[0029] The present invention preferably washes, dries, and jaw-crushes or hammer-crushes the barite ore with a barium sulfate content of ≥95% to obtain barite particles with a particle size of 10 to 50 mm.

[0030] In the present invention, in the step (1), the particle size of the barite particles is 10 to 50 mm; a composite ball milling aid is added during the ball milling, wherein the composite ball milling aid is compounded from an acrylic block copolymer dispersant and a non-ionic dispersant.

[0031] In the present invention, the grinding is carried out in a ring roller mill to obtain coarse barite powder.

[0032] In the present invention, the mass ratio of the acrylic block copolymer dispersant to the nonionic dispersant is 4:1-3, preferably 4:1, 4:2, 4:3.

[0033] The present invention adopts acrylic acid block copolymer type dispersant and nonionic dispersant as ball milling aids, which can improve the water resistance of the product.

[0034] In the present invention, based on the mass of the barite coarse powder obtained by grinding, the addition amount of the composite ball milling aid is 4-8‰, preferably 4‰, 6‰, and 8‰; the composite ball milling aid is diluted with water before adding, and the dilution ratio is 6-8:1, preferably 6:1, 7:1, and 8:1.

[0035] In the present invention, the filling rate of the ball milling medium during ball milling is 50-60%, preferably 50%, 55%, 60%; the ball milling medium is a compound of ceramic balls of different sizes, and the compounding ratio of 30mm ceramic balls: 20mm ceramic balls: 10mm ceramic balls is 1:2-3:3-5, preferably 1:2:3, 1:3:4, 1:3:5. The present invention preferably uses a single-bin ball mill with full ceramic lining. Since the feed material is relatively fine, the ball mill mainly performs ultrafine grinding without a coarse grinding stage. Therefore, the entire ball milling area is ultrafine grinding, and the ball milling media are all compounded with small-sized ceramic balls, and there is no need for compartment separation.

[0036] In the present invention, in the step (1), the two classifications include a primary classification and a secondary classification, which are carried out in series using a 4-head classification wheel and a 6-head classification wheel, wherein the 4-head classification wheel is a straight-edge classification wheel with a classifier frequency of 36 to 38 Hz, and the 6-head classification wheel is a bevel-edge classification wheel with a classifier frequency of 64 to 66 Hz.

[0037] In the present invention, the mass ratio of the stearic acid emulsion to the tetraneoalkoxybis(didecylphosphite)titanate coupling agent is 1:2-4, preferably 1:2, 1:3, 1:4.

[0038] In the present invention, based on the mass of the barite raw powder, the addition amount of the composite modifier is 5-8‰, preferably 5‰, 7‰, 8‰; the composite modifier is diluted with water before addition, and the dilution ratio is 1:1-3, preferably 1:1, 1:2, 1:3.

[0039] In the present invention, the temperature of the surface modification treatment is 100-110°C, preferably 100°C, 105°C, 110°C, and the time is 10-20min, preferably 10min, 15min, 20min; the cooling time is 20-30min, preferably 20min, 25min, 30min.

[0040] In the present invention, the cooling is carried out in a powder flow heat exchanger, which is a vertical heat exchanger. The temperature is gradually reduced from top to bottom, and the high-temperature area at the front end plays a certain degree of heat treatment role, so that the surface modifier is further wetted and coated on the surface of the material, further improving the surface modification effect. The material is discharged by its own gravity, and the material can be cooled and conveyed without additional mechanical stirring, reducing the risk of the modifier being detached from the material surface under the action of shear force when a traditional high-mixer adopts a cold mixing process during cooling after modification.

[0041] The present invention also provides natural superfine barium sulfate powder without sand grinding, which is prepared by the method for preparing the natural superfine barium sulfate powder without sand grinding.

[0042] The present invention also provides an application of the above-mentioned sand-free natural ultrafine barium sulfate powder in coatings.

[0043] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0044] The detailed information of the reagents used in the examples of the present invention are as follows:

[0045] The manufacturer of acrylic block copolymer dispersant is BASF, and the brand name is Ultra PX 4575;

[0046] The manufacturer of the nonionic dispersant is BASF, and the brand name is UltraPX 4522;

[0047] The manufacturer of stearic acid emulsion is Luoyang Yefang New Material Technology Co., Ltd.;

[0048] The manufacturer of tetraneoalkoxybis(didecylphosphite)titanate coupling agent is Nanjing Nengde New Materials Technology Co., Ltd., and the brand name is TCA-K55.

[0049] Example 1

[0050] Select barite concentrate with barium sulfate content ≥95%, wash, dry and crush in two stages to obtain barite particles with a diameter of 10-50 mm, convey them into a YFM-318 roller mill through a spiral auger for grinding, and obtain coarse barite powder with D50=5.18μm and D97=10.51μm, convey them into a fully ceramic lined single-bin ball mill with a specification of 2.2m*8.0m through a spiral auger. The composite ball milling aid is added in a dilution manner, and the dilution ratio is 6:1 (water: composite ball milling aid). The addition amount of the composite ball milling aid (acrylic block copolymer dispersant: non-ionic dispersant = 4:1) accounts for 4‰ of the mass of the barite coarse powder. The ball milling medium filling rate in the ball mill is 50%, and the composite ratio of the ceramic ball milling medium is 30mm: 20mm: 10mm = 1:2:3. After ball milling, two classifications are performed, using 4-head classification wheels and 6-head classification wheels in series, of which 4 The classifying wheel is a straight-edge classifying wheel, the frequency of the primary classifier is 36Hz, the 6-head classifying wheel is a bevel-edge classifying wheel, and the frequency of the secondary classifier is 64Hz. After cyclone collection, the barite raw powder enters the raw powder silo. After testing, D50 is 1.05μm, D97 is 2.90μm, and the content of ≤2μm is 76.12%. The barite raw powder material is transported into the high-speed mixer through the conveying system for surface modification. The composite modifier is added by water dilution at the front end of the conveying system. The dilution ratio is The ratio of composite modifier to water is 1:1, wherein the addition amount of composite modifier (stearic acid emulsion: tetraneoalkoxybis(didecylphosphite) titanate coupling agent = 1:2) accounts for 5‰ of the mass of barite raw powder, the material temperature is 100°C, the modification time is 10min, and the modified high-temperature material is transported through a pipeline into a powder flow heat exchanger for cooling. The cooling time is 20min. The cooled material enters the finished product silo through the conveying system, and is screened, tested, and packaged.

[0051] Example 2

[0052] Select barite concentrate with barium sulfate content ≥95%, wash, dry and crush in two stages to obtain barite particles with a diameter of 10-50 mm, convey them into a YFM-318 roller mill through a spiral auger for grinding, and obtain coarse barite powder with D50=5.22μm and D97=10.83μm, convey them into a fully ceramic lined single-bin ball mill with a specification of 2.2m*8.0m through a spiral auger. The composite ball milling aid is added in a dilution manner, the dilution ratio is 7:1 (water: composite ball milling aid), the addition amount of the composite ball milling aid (acrylic block copolymer dispersant: non-ionic dispersant = 2:1) accounts for 6‰ of the mass of the barite coarse powder, the ball milling medium filling rate in the ball mill is 55%, and the composite ratio of the ceramic ball milling medium is 30mm:20mm:10mm=1:3:4. After ball milling, two classifications are performed, using 4-head classification wheels and 6-head classification wheels in series, of which 4 The classifying wheel is a straight-edge classifying wheel, the frequency of the primary classifier is 37Hz, the 6-head classifying wheel is a beveled-edge classifying wheel, and the frequency of the secondary classifier is 66Hz. After cyclone collection, the barite raw powder enters the raw powder silo. After testing, D50 is 1.01μm, D97 is 2.62μm, and the content of ≤2μm is 79.36%. The barite raw powder material is transported into the high-speed mixer through the conveying system for surface modification. The composite modifier is added by water dilution at the front end of the conveying system. The dilution ratio is The ratio of composite modifier to water is 1:2 (composite modifier: water), wherein the addition amount of composite modifier (stearic acid emulsion: tetraneoalkoxybis(didecylphosphite) titanate coupling agent = 1:3) accounts for 7‰ of the mass of barite raw powder, the material temperature is 105°C, the modification time is 15min, and the modified high-temperature material is transported through a pipeline into a powder flow heat exchanger for cooling. The cooling time is 25min. The cooled material enters the finished product silo through the conveying system, and is screened, tested, and packaged.

[0053] Example 3

[0054] Select barite concentrate with barium sulfate content ≥95%, wash, dry and crush in two stages to obtain barite particles with a diameter of 10-50 mm, convey them into a YFM-318 roller mill through a spiral auger for grinding, and obtain barite coarse powder with D50=5.18μm and D97=10.23μm, convey them into a single-bin ball mill with full ceramic lining and specifications of 2.2m*8.0m through a spiral auger conveying system. Grinding aids were added by dilution with water, the dilution ratio was 8:1 (water: composite ball milling aid), the addition amount of composite ball milling aid (acrylic block copolymer dispersant: non-ionic dispersant = 4:3) accounted for 8‰ of the mass of barite coarse powder, the ball milling medium filling rate in the ball mill was 60%, the composite ratio of ceramic ball ball milling medium was 30mm: 20mm: 10mm = 1:3:5, and two classifications were performed after ball milling, using 4-head classifying wheels and 6-head classifying wheels in series, of which 4 The classifying wheel is a straight-edge classifying wheel, the frequency of the primary classifier is 38Hz, the 6-head classifying wheel is a beveled-edge classifying wheel, and the frequency of the secondary classifier is 67Hz. After cyclone collection, the barite raw powder enters the raw powder silo. After testing, D50 is 0.94μm, D97 is 2.54μm, and the content of ≤2μm is 82.99%. The barite raw powder material is transported into the high-speed mixer through the conveying system for surface modification. The composite modifier is added by water dilution at the front end of the conveying system. The dilution ratio is For example, the ratio of composite modifier to water is 1:3 (composite modifier: water), wherein the addition amount of composite modifier (stearic acid emulsion: tetraneoalkoxybis(didecylphosphite) titanate coupling agent = 1:4) accounts for 8‰ of the mass of barite raw powder, the material temperature is 110°C, the modification time is 20min, and the modified high-temperature material is transported through a pipeline into a powder flow heat exchanger for cooling. The cooling time is 30min. The cooled material enters the finished product silo through the conveying system, and is screened, tested, and packaged.

[0055] Performance testing:

[0056] The sand-free natural ultrafine barium sulfate powder, conventional ultrafine barium sulfate powder and conventional precipitated barium sulfate powder products prepared in Examples 1 to 3 were tested for relevant indicators according to GB / T 2899-2008, wherein the manufacturer of the conventional ultrafine barium sulfate powder is Jiangxi Guangyuan Chemical Co., Ltd., with a brand name of GY-6000; the manufacturer of the conventional precipitated barium sulfate powder is Shaanxi Fuhua Chemical Co., Ltd., and the test results are shown in Table 1:

[0057] Table 1 Performance test results

[0058]

[0059]

[0060] Application Examples

[0061] The sand-free natural ultrafine barium sulfate powder, conventional ultrafine barium sulfate powder and conventional precipitated barium sulfate powder products prepared in Examples 1 to 3 were respectively applied to water-based industrial paints, wherein the manufacturer of the water-based epoxy ester resin is Changzhou Guangshu Chemical Technology Co., Ltd., with a brand of GS-5000B; the manufacturer of the water-based drier is Guangdong Sandingjia New Material Technology Co., Ltd., with a brand of SDJ9903; the manufacturer of the thickener 299 is Hemingsdeqian, and the specific formula of the water-based industrial paint is shown in Table 2;

[0062] Table 2 Water-based industrial paint formula

[0063]

[0064]

[0065] The above-mentioned water-based industrial paint was subjected to performance testing. The testing standards and test results are shown in Table 3.

[0066] Table 3 Water-based industrial paint performance test results

[0067]

[0068] As can be seen from Table 3, the sand-free natural ultrafine barium sulfate powder prepared by the present invention is applied to water-based industrial paint, and its dispersibility is significantly better than that of conventional ultrafine barium sulfate powder and conventional precipitated barium sulfate powder, and its glossiness is comparable to that of conventional ultrafine barium sulfate powder and conventional precipitated barium sulfate powder, and its water resistance and storage stability are significantly better than those of conventional ultrafine barium sulfate powder and conventional precipitated barium sulfate powder. The sand-free natural ultrafine barium sulfate powder prepared by the present invention is applied to water-based industrial paint without sand grinding, which can significantly shorten the dispersion time and effectively improve production efficiency.

[0069] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing natural ultrafine barium sulfate powder without sand grinding, characterized in that: The steps include: (1) grinding, ball milling, and twice classifying the barite particles in sequence to obtain barite raw powder; (2) subjecting the raw barite powder to surface modification treatment and cooling to obtain natural ultrafine barium sulfate powder without sand grinding; A composite modifier is added during the surface modification treatment; the composite modifier is prepared by compounding stearic acid emulsion and tetraneoalkoxy bis (didecyl phosphite acyloxy) titanate coupling agent.

2. The method for preparing natural ultrafine barium sulfate powder without sand grinding according to claim 1, characterized in that: In the step (1), the particle size of the barite particles is 10 to 50 mm; and a composite ball milling aid is added during the ball milling, wherein the composite ball milling aid is compounded from an acrylic block copolymer dispersant and a non-ionic dispersant.

3. The method for preparing natural ultrafine barium sulfate powder without sand grinding according to claim 2, characterized in that: The mass ratio of the acrylic block copolymer dispersant to the nonionic dispersant is 4:1-3.

4. The method for preparing natural ultrafine barium sulfate powder without sand grinding according to claim 2 or 3, characterized in that: The addition amount of the composite ball milling aid is 4-8‰ based on the mass of the barite coarse powder obtained by grinding; the composite ball milling aid is diluted with water before being added, and the dilution ratio is 6-8:

1.

5. The method for preparing natural ultrafine barium sulfate powder without sand grinding according to claim 4, characterized in that: In the step (1), the two classifications include a primary classification and a secondary classification, which are performed in series using a 4-head classification wheel and a 6-head classification wheel, wherein the 4-head classification wheel is a straight-edge classification wheel with a classifier frequency of 36 to 38 Hz, and the 6-head classification wheel is a bevel-edge classification wheel with a classifier frequency of 64 to 66 Hz.

6. The method for preparing natural ultrafine barium sulfate powder without sand grinding according to claim 2, 3 or 5, characterized in that: The mass ratio of the stearic acid emulsion to the tetraneoalkoxybis(didecylphosphite acyloxy)titanate coupling agent is 1:2-4.

7. The method for preparing natural ultrafine barium sulfate powder without sand grinding according to claim 6, characterized in that: The addition amount of the composite modifier is 5-8‰ based on the mass of the barite raw powder; the composite modifier is diluted with water before being added, and the dilution ratio is 1:1-3.

8. The method for preparing natural ultrafine barium sulfate powder without sand grinding according to claim 5 or 7, characterized in that: The surface modification treatment is carried out at a temperature of 100 to 110° C. for 10 to 20 minutes; and the cooling time is 20 to 30 minutes.

9. The natural superfine barium sulfate powder without sand grinding obtained by the method for preparing the natural superfine barium sulfate powder without sand grinding according to any one of claims 1 to 8.

10. Use of the sand-free natural ultrafine barium sulfate powder according to claim 9 in coatings.

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