A method for preparing highly dispersed aluminum zinc phosphate anti-rust pigment

Abstract

The present invention discloses a method for preparing a highly dispersed aluminum zinc phosphate anti-rust pigment. The method uses a four-temperature zone tubular furnace as a reactor, and comprises the following steps: (1) placing phosphoric acid in the first temperature zone of the tubular furnace to prepare a volatile substance A; (2) placing zinc oxide in the second temperature zone of the tubular furnace to prepare a volatile substance B; (3) placing aluminum oxide in the third temperature zone of the tubular furnace to prepare a volatile substance C; (4) placing a collector at the bottom of the fourth temperature zone; and (5) adjusting the pressure to allow the volatile substances A, B, and C to react with each other, allowing the reaction product to settle in the collector, and removing the collector to obtain the aluminum zinc phosphate product. The preparation method of the present invention can obtain a nanometer-scale highly dispersed aluminum phosphate product, which can be applied to coatings to obtain good dispersibility, improve the compatibility of water-based resins in the system, and further improve corrosion resistance.

Description

Technical Field

[0001] The invention relates to the technical field of rust-proof pigment production, and in particular to a method for preparing highly dispersed aluminum zinc phosphate rust-proof pigment. Background Art

[0002] Zinc aluminum phosphate is an inorganic compound containing phosphorus, aluminum and zinc. It is a new generation of green and environmentally friendly white anti-rust pigment. The product is non-toxic and pollution-free and can be used to replace traditional toxic heavy metal anti-rust pigments such as red lead and zinc chrome yellow. Moreover, with the increasing demand for environmentally friendly anti-rust pigments in the domestic and foreign markets, the market prospects of zinc aluminum phosphate products are broad.

[0003] Invention patent CN109534311A discloses a method for preparing aluminum zinc phosphate, which includes the following steps: step 1, through a material box, put a certain amount of zinc oxide and an appropriate amount of water into a reactor, and gently stir to obtain zinc oxide slurry. Step 2, put a certain amount of aluminum oxide and phosphoric acid into the reactor. Step 3, add zinc dihydrogen phosphate solution to the zinc oxide reactor in batches. Step 4, transfer the reacted liquid to a centrifuge through a pipeline to remove moisture and impurities. Step 5, dry the obtained water-containing solid through a dryer. Step 6, pass through a crushing device and a gas cyclone device to obtain qualified aluminum zinc phosphate. The beneficial effect of the preparation method of aluminum zinc phosphate of the present invention is that its preparation process flow is reasonably designed, the finished product of aluminum zinc phosphate is of high quality and high production efficiency, the loss of raw materials for the preparation of aluminum zinc phosphate is reduced, the economic benefit is improved, and labor costs are saved.

[0004] Invention patent BR8107979A discloses a method for preparing aluminum zinc phosphate hydrate or alkaline aluminum zinc phosphate hydrate. The aluminum zinc phosphate hydrate or alkaline aluminum zinc phosphate hydrate is prepared by reacting 1 mol of aluminum hydrogen phosphate with 2.4 to 4 mol of zinc oxide, and, if necessary, adding up to 0.4 mol of an alkali metal aluminate or an equivalent amount of an alkali metal hydroxide. A 50% by weight acidic aluminum hydrogen phosphate solution is preferably used for the reaction, which is carried out at an elevated temperature of 30-80°C. The aluminum zinc phosphate hydrate prepared by this method is a useful anti-corrosion pigment for paints.

[0005] Invention patent CN116285427A discloses a method for preparing an organically modified aluminum zinc phosphate anti-rust pigment, comprising the following steps: (1) pre-dispersing zinc oxide, then adding a dispersant and stirring; (2) controlling the molar ratio of phosphoric acid to aluminum hydroxide to conduct a neutralization reaction to prepare an aluminum dihydrogen phosphate solution; (3) sand-grinding the pre-dispersed zinc oxide, and dropwise adding the aluminum dihydrogen phosphate solution to the zinc oxide dispersion to react to prepare aluminum zinc phosphate; (4) adding an organic modifier to the aluminum zinc phosphate to react, and finally filtering, washing, and drying to obtain the organically modified aluminum zinc phosphate. The organically modified aluminum zinc phosphate pigment prepared by the present invention has better anti-flash rust performance in a water-based coating system, and also provides it with better inhibition performance and long-term anti-rust effect. At the same time, it can greatly reduce the addition of anti-flash rust agents harmful to the human body, such as sodium nitrite, and is a more environmentally friendly anti-rust pigment.

[0006] The existing technology prepares aluminum zinc phosphate in an aqueous solution. After the synthesis stage, if you want to obtain a highly dispersed ultrafine powder product, you need to consume energy to carry out drying, crushing, grinding and other processes to obtain a product with a finer particle size. The process is complicated, the synthesis rate is low, and the production efficiency is low. Summary of the Invention

[0007] In response to the above technical problems, the present invention provides a new process for preparing highly dispersed aluminum zinc phosphate, obtaining a nano-scale highly dispersed aluminum phosphate product, which is applied to coatings to obtain good dispersibility, improve the solubility of water-based resins in the system, and further improve the corrosion resistance.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for preparing highly dispersed aluminum zinc phosphate anti-rust pigment, using a four-temperature zone tubular furnace as a reactor, comprises the following steps:

[0010] (1) placing phosphoric acid in the first temperature zone of a tube furnace to prepare volatile substance A;

[0011] (2) placing zinc oxide in the second temperature zone of a tube furnace to prepare volatile substance B;

[0012] (3) placing alumina in the third temperature zone of a tube furnace to prepare volatile substance C;

[0013] (4) placing a collector at the bottom of the fourth temperature zone;

[0014] (5) Adjusting the pressure to allow volatile substances A, B, and C to react with each other, and allowing the reaction products to settle in a collector. The collector is then removed to obtain an aluminum zinc phosphate product.

[0015] Preferably, in step (1), the temperature of the first temperature zone is controlled to be 170-190°C.

[0016] Preferably, in step (2), the temperature of the second temperature zone is controlled to be 2000-2200°C.

[0017] Preferably, in step (3), the temperature of the third temperature zone is controlled to be 3000-3200°C.

[0018] Preferably, in step (4), the temperature of the fourth temperature zone is controlled to be 100-120°C.

[0019] Preferably, in step (4), the surface of the collector is covered with nano-scale crystal seeds.

[0020] Preferably, the nano-scale seed crystals are nano zinc oxide.

[0021] Preferably, in step (5), the pressure is adjusted to 0.1013 MPa.

[0022] Preferably, in step (5), the reaction time is 20 to 40 minutes.

[0023] Preferably, in step (5), after the reaction is completed, the pressure in the tube is kept constant, and the collector is removed after the temperature drops to room temperature.

[0024] Preferably, the molar ratio of the phosphoric acid, zinc oxide and aluminum oxide is 3:3:1.

[0025] The beneficial effects of the present invention compared with the prior art are as follows:

[0026] 1. The present invention obtains a nano-sized, uniform aluminum zinc phosphate powder product through direct reaction, omitting the steps of filtering, drying, grinding, etc., greatly streamlining the process and saving costs.

[0027] 2. The aluminum zinc phosphate powder product prepared by the present invention is a monodisperse phase and can have high dispersibility in the coating without further modification or addition of additives, thereby reducing the coating manufacturing cost.

[0028] 3. The present invention is a gas-solid phase reaction, the preparation process is simple, the reaction process can be accurately controlled, the product synthesis rate is high, and the production efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the dispersibility of the aluminum zinc phosphate anti-rust pigment prepared in Example 1 of the present invention when applied to a water-based coating (without adding a dispersant) using a scraper fineness meter;

[0030] Figure 2 This is a schematic diagram of the dispersibility of the aluminum zinc phosphate anti-rust pigment prepared in Example 2 of the present invention when applied to a water-based coating (without adding a dispersant) and tested using a scraper fineness meter;

[0031] Figure 3 This is a schematic diagram of the dispersibility of the aluminum zinc phosphate anti-rust pigment prepared in Example 3 of the present invention when applied to a water-based coating (without adding a dispersant) and tested using a scraper fineness meter;

[0032] Figure 4 This is a schematic diagram of the dispersibility of the aluminum zinc phosphate anti-rust pigment prepared in Comparative Example 1 of the present invention when applied to a water-based coating (without adding a dispersant) and tested using a scraper fineness meter;

[0033] Figure 5 This is a schematic diagram of the dispersibility effect of the aluminum zinc phosphate anti-rust pigment prepared in Comparative Example 1 of the present invention when applied to a water-based paint (with a dispersant added) and tested using a scraper fineness meter. DETAILED DESCRIPTION

[0034] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0035] Example 1

[0036] A method for preparing highly dispersed aluminum zinc phosphate anti-rust pigment, using a four-temperature zone tubular furnace as a reactor, comprises the following steps:

[0037] (1) placing 3 mol of phosphoric acid in the first temperature zone of a tube furnace, controlling the temperature of the first temperature zone to 180° C., and preparing volatile substance A;

[0038] (2) placing 3 mol of zinc oxide in the second temperature zone of a tube furnace and controlling the temperature of the second temperature zone to 2000° C. to prepare volatile substance B;

[0039] (3) placing 1 mol of alumina in the third temperature zone of a tube furnace, controlling the temperature of the third temperature zone to 3100° C., and preparing volatile substance C;

[0040] (4) placing a collector with a surface covered with nano-sized seed zinc oxide at the bottom of the fourth temperature zone, and controlling the temperature of the fourth temperature zone to be 110°C;

[0041] (5) Air, a carrier gas, is introduced and the pressure is adjusted to 0.1013 MPa to allow volatile substances A, B, and C to react. The reaction time is 30 min, and the reaction product is allowed to settle in a collector. After the reaction is completed, the pressure in the tube is maintained constant. The collector is removed after the temperature drops to room temperature to obtain the aluminum zinc phosphate product. The powder particle size is 10 to 20 nm.

[0042] Example 2

[0043] A method for preparing highly dispersed aluminum zinc phosphate anti-rust pigment, using a four-temperature zone tubular furnace as a reactor, comprises the following steps:

[0044] (1) 3 mol of phosphoric acid was placed in the first temperature zone of a tube furnace, and the temperature of the first temperature zone was controlled at 180° C. to prepare volatile substance A;

[0045] (2) placing 3 mol of zinc oxide in the second temperature zone of a tube furnace and controlling the temperature of the second temperature zone to 2100° C. to prepare volatile substance B;

[0046] (3) placing 1 mol of alumina in the third temperature zone of a tube furnace, controlling the temperature of the third temperature zone to 3100° C., and preparing volatile substance C;

[0047] (4) placing a collector covered with nano-sized crystal seeds at the bottom of the fourth temperature zone, and controlling the temperature of the fourth temperature zone to be 120°C;

[0048] (5) Air, a carrier gas, is introduced and the pressure is adjusted to 0.1013 MPa to allow volatile substances A, B, and C to react. The reaction time is 40 min, and the reaction product is allowed to settle in a collector. After the reaction is completed, the pressure in the tube is maintained constant. The collector is removed after the temperature drops to room temperature to obtain the aluminum zinc phosphate product. The powder particle size is 15-20 nm.

[0049] Example 3

[0050] A method for preparing highly dispersed aluminum zinc phosphate anti-rust pigment, using a four-temperature zone tubular furnace as a reactor, comprises the following steps:

[0051] (1) 3 mol of phosphoric acid was placed in the first temperature zone of a tube furnace, and the temperature of the first temperature zone was controlled at 190° C. to prepare volatile substance A;

[0052] (2) placing 3 mol of zinc oxide in the second temperature zone of a tube furnace and controlling the temperature of the second temperature zone to 2000° C. to prepare volatile substance B;

[0053] (3) placing 1 mol of alumina in the third temperature zone of a tube furnace, controlling the temperature of the third temperature zone to 3200° C., and preparing volatile substance C;

[0054] (4) placing a collector covered with nano-sized crystal seeds at the bottom of the fourth temperature zone, and controlling the temperature of the fourth temperature zone to be 100°C;

[0055] (5) Air, a carrier gas, is introduced and the pressure is adjusted to 0.05 MPa to allow volatile substances A, B, and C to react. The reaction time is 20 min, and the reaction product is allowed to settle in a collector. After the reaction is completed, the pressure in the tube is maintained constant. The collector is removed after the temperature drops to room temperature to obtain the aluminum zinc phosphate product. The powder particle size is 10 to 25 nm.

[0056] Comparative Example 1

[0057] The traditional solution method for preparing aluminum zinc phosphate comprises the following steps: (1) pre-dispersing zinc oxide; (2) controlling the molar ratio of phosphoric acid to aluminum hydroxide to carry out a neutralization reaction to prepare an aluminum dihydrogen phosphate solution; (3) adding the aluminum dihydrogen phosphate solution dropwise to the zinc oxide dispersion to react and prepare aluminum zinc phosphate; (4) filtering, washing, drying, and grinding to obtain a powder of the traditional solution method aluminum zinc phosphate product, with a particle size generally ranging from 3 to 10 μm.

[0058] Comparative experiment

[0059] The aluminum zinc phosphate prepared in Examples 1-3 and Comparative Example 1 was applied to a water-based acrylic resin, resulting in water-based acrylic coatings labeled ①-④, respectively. The aluminum zinc phosphate prepared in Comparative Example 1 was applied to a water-based acrylic resin and a dispersant was added, resulting in a water-based acrylic coating labeled ⑤. The dispersibility and compatibility of the aluminum zinc phosphate in the coatings were compared by observing the particle size remaining on a scraper fineness meter.

[0060] The raw material ratios of each group are shown in Table 1:

[0061] Table 1

[0062]

[0063]

[0064] The results are shown in Table 2 below.

[0065] Table 2

[0066] Group Powder particle size Dispersibility ① 10~20nm Good dispersibility and good paint suspension ② 15~30nm Good dispersibility and good paint suspension ③ 10~25nm Good dispersibility and good paint suspension ④ 3~10μm The powder is difficult to wet, agglomerates, has coarse particles, and is difficult to disperse ⑤ 3~10μm Dispersibility has improved, slightly worse than ①~③

[0067] As can be seen from Table 2, compared with ④ to ⑤, the aluminum zinc phosphate prepared by the present invention has higher dispersibility, uniform particle dispersion, and good suspension. After adding a dispersant on the basis of ④, the dispersion performance of ⑤ is improved, but it is still slightly worse than ① to ③ aluminum zinc phosphate prepared by Examples 1 to 3 of the present invention.

[0068] Depend on Figures 1 to 5 It can be seen that the aluminum zinc phosphate prepared by the present invention is used in water-based coatings: (1) Figures 1 to 3 In the water-based paint, the powder is evenly dispersed in the water-based acrylic resin and has good suspension properties; Figure 4 In the present invention, the aluminum zinc phosphate prepared by the traditional solution method is difficult to disperse in the water-based propionic resin, and the whole system is agglomerated, sticky, and produces coarse particles; (2) When the aluminum zinc phosphate prepared by the traditional solution method is used in the water-based propionic resin, the addition of a dispersant can visibly improve the agglomeration, stickiness, and coarse particle phenomena of the system, that is, the dispersion performance of the system is improved, but it is still relatively poor compared with the aluminum zinc phosphate prepared by the present invention, indicating that the aluminum zinc phosphate prepared by the present invention has high dispersion performance.

[0069] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing highly dispersed aluminum zinc phosphate anti-rust pigment, characterized in that: A four-temperature zone tubular furnace is used as a reactor, comprising the following steps: (1) placing phosphoric acid in the first temperature zone of a tube furnace to prepare volatile substance A; (2) placing zinc oxide in the second temperature zone of a tube furnace to prepare volatile substance B; (3) placing alumina in the third temperature zone of a tube furnace to prepare volatile substance C; (4) placing a collector at the bottom of the fourth temperature zone; (5) Adjusting the pressure to allow volatile substances A, B, and C to react with each other, and allowing the reaction products to settle in a collector. The collector is then removed to obtain an aluminum zinc phosphate product.

2. The method for preparing a highly dispersed aluminum zinc phosphate antirust pigment according to claim 1, wherein: In step (1), the temperature of the first temperature zone is controlled to be 170-190°C.

3. The method for preparing a highly dispersed aluminum zinc phosphate antirust pigment according to claim 2, wherein: In step (2), the temperature of the second temperature zone is controlled to be 2000-2200°C.

4. The method for preparing a highly dispersed aluminum zinc phosphate antirust pigment according to claim 1, wherein: In step (3), the temperature of the third temperature zone is controlled to be 3000-3200°C.

5. The method for preparing a highly dispersed aluminum zinc phosphate antirust pigment according to claim 4, wherein: In step (4), the temperature of the fourth temperature zone is controlled to be 100-120°C.

6. The method for preparing a highly dispersed aluminum zinc phosphate antirust pigment according to claim 1, wherein: In step (4), the surface of the collector is covered with nano-scale crystal seeds.

7. The method for preparing a highly dispersed aluminum zinc phosphate antirust pigment according to claim 6, wherein: The nano-scale seed crystal is nano zinc oxide.

8. The method for preparing a highly dispersed aluminum zinc phosphate antirust pigment according to claim 1, wherein: In step (5), the pressure is adjusted to 0.1013-0.5 MPa.

9. The method for preparing a highly dispersed aluminum zinc phosphate antirust pigment according to claim 1, wherein: In step (5), the reaction time is 20 to 40 minutes.

10. The method for preparing highly dispersed aluminum zinc phosphate antirust pigment according to claim 1, characterized in that: In step (5), after the reaction is completed, the pressure in the tube is kept constant, and the collector is removed after the temperature drops to room temperature.

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