Extinction barium sulfate as well as preparation method and application thereof

Abstract

The invention provides extinction barium sulfate as well as a preparation method and application thereof, and belongs to the technical field of powder coatings. Natural high-grade barite concentrate with the barium sulfate content larger than 97% is adopted as a raw material, large-particle-size barium sulfate raw powder (D50 ranges from 10 micrometers to 12 micrometers, D97 ranges from 20 micrometers to 24 micrometers, and D100 ranges from 28 micrometers to 33 micrometers) with narrow particle size distribution is obtained through grinding of a short-barrel ball mill and a secondary grading technology, light calcium carbonate with the weight being 70 ml / 100 g, the whiteness larger than 98.5 and the crystal shape being in a golf ball shape is adopted as an auxiliary delustering agent, and the high-purity barium sulfate powder is obtained. The light scattering and diffuse reflection efficiency of the product is improved to improve the matting performance, meanwhile, the compatibility of light calcium carbonate and resin is improved through surface modification treatment, a matting barium sulfate product is obtained, and when the matting barium sulfate product is applied to a matting powder coating, the appearance and the matting performance of a coating film can be both considered (the glossiness is smaller than 30 degrees).

Description

Technical Field

[0001] This invention relates to the field of powder coating technology, and in particular to a matting barium sulfate, its preparation method, and its application. Background Technology

[0002] Powder coatings are solid powdered synthetic resin coatings composed of solid resin, pigments, fillers, and additives. They are characterized by solvent-free production, 100% film formation, and low energy consumption, and are widely used in building profiles, construction machinery, fire-fighting equipment, medium-density fiberboard, and other fields. Powder coatings are classified into high-gloss and matte powder coatings based on the gloss level of the coating film. Matte powder coatings are mainly used in home appliances, security doors, and aluminum ceilings.

[0003] Currently, the mainstream matting methods are mainly divided into physical matting and chemical matting. Physical matting mainly involves adding large-particle fillers to increase the surface roughness of the coating. However, the limit of physical matting is generally <30°. If the matting effect is achieved solely through physical matting, the appearance of the coating will be severely affected due to insufficient smoothness of the paint film. Chemical matting mainly uses a mixture of two resins with different acid values ​​to achieve chemical matting by varying the curing speeds of the resins. It can achieve a matting effect below 30°. However, the coating prepared by this method is discontinuous and incompatible in the microscopic state, resulting in poor mechanical properties. This is very unfavorable for the secondary processing and forming of aluminum profiles after pre-coating, and its use is greatly limited.

[0004] Therefore, in matte polyester powder coatings, a matting method that can balance the appearance and mechanical properties of the coating film has become an urgent need in the industry. Summary of the Invention

[0005] The purpose of this invention is to provide a barium sulfate for dulling light, its preparation method, and its application, in order to solve the above-mentioned technical problems.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing barium sulfate that has dulled fluorescence, comprising the following steps:

[0008] 1) The high-grade barite concentrate was crushed twice and then ground to obtain powder 1;

[0009] 2) Powder 1 was sequentially classified once and twice to obtain barium sulfate raw powder No. 1 and barium sulfate raw powder No. 2, respectively;

[0010] 3) Light calcium carbonate is subjected to primary and secondary surface modification in sequence to obtain modified light calcium carbonate;

[0011] 4) The No. 2 barium sulfate raw powder and the modified light calcium carbonate are mixed in the first and second mixing processes in sequence. The resulting mixture is the matting barium sulfate.

[0012] Furthermore, in step 1), the grinding medium is ceramic balls of different diameters, the filling rate of the medium is 50-60%, and a grinding aid is added during the grinding process. The amount of grinding aid added is 2-4‰ of the mass of powder 1.

[0013] Furthermore, the grinding aid is obtained by compounding ethanol and water in a mass ratio of 1:3 to 5.

[0014] Furthermore, in step 2), the D50 of the No. 1 barium sulfate raw powder obtained after one classification is 8-11 μm, the D97 is 25-30 μm, and the D100 is 35-42 μm.

[0015] The No. 2 barium sulfate raw powder obtained after secondary classification has a D50 of 10-12 μm, a D97 of 20-24 μm, and a D100 of 28-33 μm.

[0016] Furthermore, in step 3), the surface modification is carried out in a high-speed mixer at a speed of 900-1100 r / min for a modification time of 10-20 min, and 1-3‰ of No. 1 modifier powder is added.

[0017] Secondary surface modification was carried out in a high-speed mixer at a speed of 1100-1300 r / min for 10-15 min, with 2-4‰ of No. 2 modifier added from powder 1.

[0018] Furthermore, in step 4), the rotation speed of the first mixing is 600-800 r / min, and the mixing time is 8-12 min;

[0019] The second mixing speed is 300-500 r / min, and the mixing time is 10-15 min.

[0020] Furthermore, the No. 1 modifier is obtained by compounding titanium ammonium lactate chelate and distearyloxyisopropoxyaluminate, with a compounding mass ratio of titanium ammonium lactate chelate: distearyloxyisopropoxyaluminate = 2~3:1;

[0021] The No. 2 modifier is obtained by compounding γ-mercaptopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane and ethanol in a mass ratio of 1-2:1:2-3.

[0022] Furthermore, the mass ratio of the No. 2 barium sulfate raw powder to the modified light calcium carbonate is 6-8:1.

[0023] The present invention also provides barium sulfate for dulling produced by the above preparation method.

[0024] The present invention also provides the application of the above-mentioned matting barium sulfate in powder coatings.

[0025] The beneficial effects of this invention are:

[0026] This invention uses high-grade natural barite concentrate with a barium sulfate content >97% as raw material. A narrow-particle-size barium sulfate raw powder (D50 10-12μm, D97 20-24μm, D100 28-33μm) is obtained through short-cylinder ball milling and secondary classification. Light calcium carbonate (70mL / 100g, whiteness >98.5, golf ball-shaped crystals) is used as an auxiliary matting agent to improve the product's light scattering and diffuse reflection efficiency, thereby enhancing its matting performance. Simultaneously, surface modification treatment improves the compatibility of the light calcium carbonate with the resin, resulting in a matting barium sulfate product. When applied to matting powder coatings, it can balance the appearance of the coating film with its matting performance (gloss <30°). Attached Figure Description

[0027] Figure 1 This is a process flow diagram of the preparation method of the present invention. Detailed Implementation

[0028] This invention provides a method for preparing barium sulfate that has dulled fluorescence, comprising the following steps:

[0029] 1) The high-grade barite concentrate was crushed twice and then ground to obtain powder 1;

[0030] 2) Powder 1 was sequentially classified once and twice to obtain barium sulfate raw powder No. 1 and barium sulfate raw powder No. 2, respectively;

[0031] 3) Light calcium carbonate is subjected to primary and secondary surface modification in sequence to obtain modified light calcium carbonate;

[0032] 4) The No. 2 barium sulfate raw powder and the modified light calcium carbonate are mixed in the first and second mixing processes in sequence. The resulting mixture is the matting barium sulfate.

[0033] In this invention, in step 1), the grinding is carried out in a short-cylinder single-compartment ball mill with a size of 1.22m*4.8m. This can effectively avoid over-grinding of the material by the ball mill, which would result in a smaller particle size and reduced grinding efficiency.

[0034] In this invention, in step 1), the grinding medium consists of ceramic balls of different diameters, with a filling rate of 50-60%. A grinding aid is added during the grinding process, with the amount added being 2-4‰ of the powder's mass. The mass ratio of the ceramic balls of different diameters is 50mm:30mm:10mm = 3-5:2-4:1-2, preferably 5:3:2. Because the material particle size is relatively coarse, the grinding medium is primarily composed of large balls, supplemented by small balls, to avoid excessive small-sized ceramic balls from causing ultra-fine grinding of the material.

[0035] In this invention, the grinding aid is obtained by compounding ethanol and water at a mass ratio of 1:3 to 5, preferably 1:4. The addition of water mainly improves the viscosity of the material and increases the friction when the grinding media contacts the material, while ethanol mainly increases the volatility of the grinding aid.

[0036] In this invention, in step 2), the D50 of the No. 1 barium sulfate raw powder obtained after one classification is 8-11 μm, the D97 is 25-30 μm, and the D100 is 35-42 μm.

[0037] The No. 2 barium sulfate raw powder obtained after secondary classification has a D50 of 10-12 μm, a D97 of 20-24 μm, and a D100 of 28-33 μm.

[0038] In this invention, the light calcium carbonate has an oil absorption value greater than 70 mL / 100 g, a whiteness greater than 98.5, and a crystal morphology in the shape of a golf ball. The high whiteness of the product results in higher light scattering efficiency, which helps to improve the matting effect. At the same time, the golf ball-shaped crystal morphology and high surface roughness result in higher diffuse light reflection efficiency, which can further improve the matting efficiency. The high oil absorption will reduce the flowability of the product and increase the surface roughness of the coating film, which will also help to improve the matting performance of the product.

[0039] In this invention, in step 3), the surface modification is carried out in a high-speed mixer at a speed of 900-1100 r / min, preferably 1000 r / min; the modification time is 10-20 min, preferably 15 min; and 1-3‰ of No. 1 modifier is added by weight of powder 1, preferably 2‰.

[0040] Secondary surface modification is carried out in a high-speed mixer at a speed of 1100–1300 r / min, preferably 1200–1300 r / min; the modification time is 10–15 min, preferably 12–14 min; 2–4‰ of the mass of powder 1 of No. 2 modifier is added, preferably 3‰. The capacity of the high-speed mixer used for surface modification is 500L; the capacity of the high-speed mixer used for mixing is 800L. A smaller space is more conducive to improving the contact between the material and the modifier during surface modification, thus improving the surface modification effect, while a larger space is more conducive to the thorough mixing of the materials during powder compounding.

[0041] In this invention, in step 4), the rotation speed of the first mixing is 600-800 r / min, preferably 700 r / min; the mixing time is 8-12 min, preferably 10 min.

[0042] The second mixing speed is 300-500 r / min, preferably 400 r / min; the mixing time is 10-15 min, preferably 12 min.

[0043] In this invention, the No. 1 modifier is obtained by compounding titanium ammonium lactate chelate and distearyloxyisopropoxyaluminate, with a compounding mass ratio of titanium ammonium lactate chelate: distearyloxyisopropoxyaluminate = 2 to 3: 1, preferably 2.5: 1;

[0044] The No. 2 modifier is obtained by compounding γ-mercaptopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane and ethanol, with a compounding mass ratio of 1-2:1:2-3, preferably 1.5:1:2.5.

[0045] In this invention, the mass ratio of the No. 2 barium sulfate raw powder to the modified light calcium carbonate is 6-8:1, preferably 7:1. Light calcium carbonate is used as an auxiliary matting agent; excessive addition will severely affect the leveling properties of the coating film, while insufficient addition will result in poor matting effect.

[0046] The present invention also provides barium sulfate for dulling produced by the above preparation method.

[0047] The present invention also provides the application of the above-mentioned matting barium sulfate in powder coatings.

[0048] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0049] Example 1

[0050] Using high-grade natural barite concentrate with a barium sulfate content >97% as raw material, the material is crushed twice and then conveyed via a screw conveyor into a single-compartment short-cylinder ball mill (1.22m*4.8m) for grinding. The media filling rate is 50%, and the ratio of different ceramic balls is 50mm:30mm:10mm = 5:4:1. A grinding aid (ethanol:water = 1:5) at 2‰ of the dry powder mass is added at the front end of the screw conveyor system. After grinding, the material is classified once by a #1 classifier, collected in a bag filter, and fed into a #1 hopper. The product is then inspected by a laser particle size analyzer. Barium sulfate raw powder #1, with a D50 of 10.76 μm, D97 of 29.83 μm, and D100 of 41.26 μm, was conveyed by pneumatic conveyor to classifier #2 for secondary classification. After bag collection, it was fed into silo #2. The product, measured by a laser particle size analyzer, showed a D50 of 11.87 μm, D97 of 23.62 μm, and D100 of 32.42 μm. Light calcium carbonate (oil absorption of 72 mL / 100 g and whiteness of 98.8) was conveyed by screw conveyor to high-speed mixer #1 for surface modification treatment. The high-speed mixer operates at 900 r / min for 10 min. Modifier #1 (titanium lactate chelate: distearate isopropoxy aluminate = 2:1) at 1‰ of the dry powder mass is added to the front end of the screw conveyor system. The material in high-speed mixer #1 is then conveyed via screw conveyor into high-speed mixer #2 for secondary surface modification. The high-speed mixer operates at 1100 r / min for 10 min. Modifier #2 (γ-mercaptopropyltrimethoxy) at 2‰ of the dry powder mass is added at the front end of the screw conveyor system by dilution with water (modifier #2: water = 1:2). Silane: N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane:ethanol = 1:1:2), barium sulfate raw powder #2 and modified light calcium carbonate are transported separately through pipelines to high-speed mixer #3 for high-speed mixing at a ratio of barium sulfate:modified light calcium carbonate = 8:1. The high-speed mixer rotates at 600 r / min for 8 min. After mixing, the material is transported through pipelines to a horizontal mixer for secondary mixing at a stirring paddle speed of 300 r / min for 10 min. After mixing, the material is transported through pipelines to the finished product silo, sieved, tested, and packaged.

[0051] Example 2

[0052] Using high-grade natural barite concentrate with a barium sulfate content >97% as raw material, the material is crushed twice and then conveyed by a screw conveyor into a single-compartment short-cylinder ball mill (1.22m*4.8m) for grinding. The media filling rate is 55%, and the ratio of different ceramic balls is 50mm:30mm:10mm = 4:3:2. A grinding aid (ethanol:water = 1:4) at 3‰ of the dry powder mass is added at the front end of the screw conveyor system. After grinding, the material is classified once by a No. 1 classifier, collected in a bag filter, and fed into the No. 1 hopper. The product is then inspected by a laser particle size analyzer. Barium sulfate raw powder #1 with a measured D50 of 9.65 μm, D97 of 27.56 μm, and D100 of 39.89 μm was conveyed by pneumatic conveyor to classifier #2 for secondary classification. After bag collection, it was fed into silo #2. The product, barium sulfate raw powder #2 with a measured D50 of 11.04 μm, D97 of 22.91 μm, and D100 of 31.01 μm, was then measured by laser particle size analyzer. Light calcium carbonate (oil absorption of 72 mL / 100 g, whiteness of 98.8) was conveyed by screw conveyor to high-temperature mixer #1 for surface modification treatment. The mixer speed is 1000 r / min, and the modification time is 15 min. Modifier #1 (titanium lactate ammonium salt chelate: distearate isopropoxy aluminate = 3:1) at 2‰ of the dry powder mass ratio is added to the front end of the screw conveyor system. The material in high-speed mixer #1 is then conveyed through the screw conveyor into high-speed mixer #2 for secondary surface modification. The high-speed mixer speed is 1200 r / min, and the modification time is 13 min. Modifier #2 (γ-mercaptopropyltrimethoxysilane) at 3‰ of the dry powder mass ratio is added at the front end of the screw conveyor system by dilution with water (modifier #2: water = 1:3). Alkane: N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane:ethanol = 2:1:2), barium sulfate raw powder #2 and modified light calcium carbonate are transported separately through pipelines to high-speed mixer #3 at a ratio of barium sulfate:modified light calcium carbonate = 7:1 for high-speed mixing. The high-speed mixer rotates at 700 r / min and the mixing time is 10 min. After mixing, the material is transported through pipelines to a horizontal mixer for secondary mixing. The stirring paddle rotates at 400 r / min and the mixing time is 13 min. After mixing, the material is transported through pipelines to the finished product silo, sieved, tested, and packaged.

[0053] Example 3

[0054] Using high-grade natural barite concentrate with a barium sulfate content >97% as raw material, the material is crushed twice and then conveyed via a screw conveyor into a single-compartment short-cylinder ball mill (1.22m*4.8m) for grinding. The media filling rate is 60%, and the ratio of different ceramic balls is 50mm:30mm:10mm = 3:4:2. A grinding aid (ethanol:water = 1:3) at 4‰ of the dry powder mass is added at the front end of the screw conveyor system. After grinding, the material is classified once by a #1 classifier, collected in a bag filter, and fed into a #1 hopper. The product is then inspected by a laser particle size analyzer. Barium sulfate raw powder #1 with a measured D50 of 8.52 μm, D97 of 25.82 μm, and D100 of 36.02 μm was conveyed by pneumatic conveyor to classifier #2 for secondary classification. After bag collection, it was fed into silo #2. The product, barium sulfate raw powder #2 with a measured D50 of 10.52 μm, D97 of 20.43 μm, and D100 of 29.01 μm, was then measured by laser particle size analyzer. Light calcium carbonate (oil absorption of 72 mL / 100 g, whiteness of 98.8) was conveyed by screw conveyor to high-temperature mixer #1 for surface modification treatment. The mixer speed is 1100 r / min, and the modification time is 20 min. Modifier #1 (titanium lactate ammonium salt chelate: distearate isopropoxy aluminate = 3:1) at 3‰ of the dry powder mass ratio is added to the front end of the screw conveyor system. The material in high-speed mixer #1 is then conveyed through the screw conveyor into high-speed mixer #2 for secondary surface modification. The high-speed mixer speed is 1300 r / min, and the modification time is 15 min. Modifier #2 (γ-mercaptopropyltrimethoxysilane) at 4‰ of the dry powder mass ratio is added at the front end of the screw conveyor system by dilution with water (modifier #2: water = 1:3). Alkane: N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane:ethanol = 2:1:3), barium sulfate raw powder #2 and modified light calcium carbonate are transported separately through pipelines to high-speed mixer #3 for high-speed mixing at a ratio of barium sulfate:modified light calcium carbonate = 6:1. The high-speed mixer rotates at 800 r / min and the mixing time is 12 min. After mixing, the material is transported through pipelines to a horizontal mixer for secondary mixing at a stirring paddle speed of 500 r / min and a mixing time of 15 min. After mixing, the material is transported through pipelines to the finished product silo, sieved, tested, and packaged.

[0055] Example 4

[0056] In this embodiment, the matting barium sulfate products prepared in Examples 1-3 were tested according to relevant indicators in accordance with GB / T37041-2018, and compared with traditional matting barium sulfate. The relevant indicators are shown in Table 1 below:

[0057] Table 1 Performance Indicators of the Examples

[0058]

[0059]

[0060] Example 5

[0061] This embodiment applies the matting barium sulfate prepared in Examples 1-3 to epoxy polyester matting powder coatings, compares it with conventional matting barium sulfate, and tests it according to relevant standards.

[0062] Table 2 Formulations of Epoxy Polyester Matte Powder Coatings

[0063] Components 1# 2# 3# 4# Polyester resin 297 297 297 297 Epoxy Resin E-12 273 273 273 273 K7237 30 30 30 30 Example 1 170 \ \ \ Example 2 \ 170 \ \ Example 3 \ \ 170 \ Barium sulfate that has been dulled \ \ \ 170 Titanium Dioxide R-219 220 220 220 220 GLP988 10 10 10 10 701B 5 5 5 5 HA501 5 5 5 5 total 1010 1010 1010 1010

[0064] The test results are shown in Table 3 below:

[0065] Table 3 Performance test results

[0066]

[0067]

[0068] As can be seen from the above embodiments, the present invention provides a matting barium sulfate, its preparation method, and its application. As shown in the table above, when the matting barium sulfate products produced using the technology of the present invention (Examples 1, 2, and 3) are applied to epoxy polyester matting powder coatings, the original coating film has low gloss and better leveling properties than ordinary matting barium sulfate. After boiling in water, the impact resistance and adhesion of the coating film are not affected. However, the impact strength and adhesion of the formulation with added ordinary barium sulfate decrease significantly, indicating that the porosity of the coating film is high, affecting its mechanical properties.

[0069] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing matting barium sulfate, characterized in that, Includes the following steps: 1) The high-grade barite concentrate was crushed twice and then ground to obtain powder 1; 2) Powder 1 was sequentially classified once and twice to obtain barium sulfate raw powder No. 1 and barium sulfate raw powder No. 2, respectively; 3) Light calcium carbonate is subjected to primary and secondary surface modification in sequence to obtain modified light calcium carbonate; 4) The No. 2 barium sulfate raw powder and the modified light calcium carbonate are mixed in the first and second mixing processes in sequence. The resulting mixture is the matting barium sulfate.

2. The method for preparing matting barium sulfate according to claim 1, characterized in that, In step 1), the grinding medium consists of ceramic balls of different diameters, with a filling rate of 50-60%. Grinding aids are added during the grinding process, with the amount of grinding aids being 2-4‰ of the mass of powder 1.

3. The method for preparing matting barium sulfate according to claim 2, characterized in that, The grinding aid is prepared by mixing ethanol and water in a mass ratio of 1:3 to 5.

4. The method for preparing matting barium sulfate according to claim 1, characterized in that, In step 2), the D50 of the No. 1 barium sulfate raw powder obtained after one classification is 8-11 μm, the D97 is 25-30 μm, and the D100 is 35-42 μm. The No. 2 barium sulfate raw powder obtained after secondary classification has a D50 of 10-12 μm, a D97 of 20-24 μm, and a D100 of 28-33 μm.

5. The method for preparing extinct barium sulfate according to claim 1, 2, or 4, characterized in that, In step 3), the surface modification is carried out in a high-speed mixer at a speed of 900-1100 r / min for 10-20 min, and 1-3‰ of No. 1 modifier powder is added. Secondary surface modification was carried out in a high-speed mixer at a speed of 1100-1300 r / min for 10-15 min, with 2-4‰ of No. 2 modifier added from powder 1.

6. The method for preparing matting barium sulfate according to claim 5, characterized in that, In step 4), the rotation speed of the first mixing is 600-800 r / min, and the mixing time is 8-12 min; The second mixing speed is 300-500 r / min, and the mixing time is 10-15 min.

7. The method for preparing matting barium sulfate according to claim 5, characterized in that, The No. 1 modifier is obtained by compounding titanium ammonium lactate chelate and distearyloxyisopropoxyaluminate, with a compounding mass ratio of titanium ammonium lactate chelate: distearyloxyisopropoxyaluminate = 2~3:1; The No. 2 modifier is obtained by compounding γ-mercaptopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane and ethanol in a mass ratio of 1-2:1:2-3.

8. The method for preparing matting barium sulfate according to claim 6 or 7, characterized in that, The mass ratio of the No. 2 barium sulfate raw powder to the modified light calcium carbonate is 6-8:

1.

9. The dulling barium sulfate prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the matting barium sulfate according to claim 9 in powder coatings.

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