Low oil absorption amount rust and corrosion preventing powder body and preparation method thereof

Abstract

The application provides a low oil absorption amount rust and corrosion preventing powder body and a preparation method thereof, and belongs to the technical field of pigments. Nano silicon dioxide is modified by a calcium salt and a silane coupling agent to obtain silicon dioxide pigment fine powder; calcium ion type silicon dioxide pigment is modified by hyperbranched polysiloxane to obtain modified calcium ion type silicon dioxide pigment; iron tripolyphosphate is modified by tannic acid to obtain modified iron tripolyphosphate, which is uniformly mixed with the silicon dioxide pigment fine powder and the modified calcium ion type silicon dioxide pigment to obtain the low oil absorption amount rust and corrosion preventing powder body. The powder body has good rust and corrosion preventing performance, the wettability, the compatibility and the dispersibility of the pigment in paint are improved, the mechanical properties of the composite pigment are improved, the oil absorption amount is greatly reduced, and the powder body has a good application prospect.

Description

Technical Field

[0001] This invention relates to the field of pigment technology, specifically to a low-oil-absorption anti-rust and anti-corrosion powder and its preparation method. Background Technology

[0002] Metal corrosion is a major challenge in modern industrial development. With technological advancements, various protective measures have been adopted to inhibit or prevent metal corrosion, thereby reducing economic losses. Among various anti-corrosion technologies, anti-corrosion coatings are one of the most widely used and effective protective methods for metal corrosion. Anti-corrosion coatings play a crucial role in metal corrosion protection in fields such as wind power generation, machinery and vehicles, and construction engineering. Currently, epoxy resin primers occupy a very important position in anti-corrosion coatings due to their good adhesion between epoxy resin and steel, low shrinkage rate, and excellent impermeability. The addition of rust-inhibiting pigments often extends the coating's lifespan, thereby improving the corrosion resistance of epoxy coatings. With rapid industrial development, industrial pollution has exacerbated environmental damage, and the requirements for rust-inhibiting pigments have shifted beyond just rust prevention effectiveness; environmental friendliness has also become an important standard.

[0003] While traditional rust-preventive pigments offer excellent corrosion protection, they also have various drawbacks. For example, red lead, one of the most traditional lead-based rust-preventive pigments, produces a denser coating when added to paint, effectively preventing moisture penetration. However, it is highly toxic, polluting the environment and posing health risks. Zinc chromium yellow, a typical chromate rust-preventive pigment, inhibits metal corrosion by reacting high-valence chromium on the metal surface to form a passivation layer of iron chromate. However, its use is restricted due to its carcinogenic risks to humans. With increasing emphasis on sustainable development and environmentally friendly practices, environmental protection and health have become major concerns, demanding new rust-preventive pigments that are environmentally friendly, cost-effective, and high-performance. Currently, the economic losses caused by metal corrosion are enormous annually. Many manufacturers have responded to market demand by developing a series of new environmentally friendly rust-preventive pigments that offer the same excellent rust-preventive performance as traditional pigments while avoiding the use of toxic compounds.

[0004] In addition, the oil absorption of anti-corrosion and anti-rust pigments in oil-based coatings and inks will affect their application performance. Excessive oil absorption makes it difficult for anti-corrosion and anti-rust pigments to disperse in the resin system, which will cause processing difficulties for PVC inks and coatings. Therefore, developing anti-corrosion and anti-rust pigments with low oil absorption can better meet the needs of downstream customers. Summary of the Invention

[0005] The purpose of this invention is to propose a low-oil-absorption rust-proof and corrosion-proof powder and its preparation method. It has good rust-proof and corrosion-proof properties, improves the wettability, compatibility and dispersibility of pigments in coatings, enhances the mechanical properties of composite pigments, and greatly reduces oil absorption, thus showing good application prospects.

[0006] The technical solution of this invention is implemented as follows:

[0007] This invention provides a method for preparing a low-oil-absorption rust-proof and corrosion-resistant powder. Nano-silica is modified with calcium salt and silane coupling agent to obtain fine silica pigment powder; calcium ion-type silica pigment is modified with hyperbranched polysiloxane to obtain modified calcium ion-type silica pigment; iron tripolyphosphate is modified with tannic acid to obtain modified iron tripolyphosphate, and these are mixed uniformly with the fine silica pigment powder and the modified calcium ion-type silica pigment to obtain the low-oil-absorption rust-proof and corrosion-resistant powder.

[0008] As a further improvement to the present invention, the following steps are included:

[0009] S1. Preparation of fine silica pigment powder: Nano silica, calcium salt, and silane coupling agent are added to water, heated and stirred to react, filtered, washed, ground, dried, and sieved to obtain fine silica pigment powder.

[0010] The silica pigment powder prepared by this invention is further modified with a silane coupling agent. The composite silane coupling agent synergistically improves the wettability and dispersibility of the pigment in the coating. The silane coupling agent KH550 has strong amino reactivity and better hydrolytic stability, which can improve the mechanical properties of the composite pigment and improve the compatibility between the pigment and the coating.

[0011] S2. Preparation of calcium ion silica pigment: Sodium silicate solution and sulfuric acid solution are mixed, stirred and reacted, aged, crushed and then water is added, the pH value is adjusted to 8.5-9, heated and stirred, kept at the temperature for aging, then the pH value is adjusted to 5.5-6, filtered, washed and dried, the solid is added to water, calcium salt is added, stirred and mixed, heated and aged, filtered, washed and dried to obtain calcium ion silica pigment.

[0012] Nano-silica, after being treated with calcium salts, yields ion-exchange nano-silica pigments, which exhibit similar anti-rust mechanisms to calcium ion-type silica pigments. When this pigment is applied to a metal surface, the surface is corroded by water, oxygen, and acids in the environment, forming a galvanic cell. Metal cations (Fe2+) are generated on the anode metal substrate. 3+ At the cathode, oxygen combines with electrons to react with water to generate hydroxide ions (OH-). - ) Silica reacts under alkaline conditions to form silicate ions (SiO3). 2- SiO3 2-Fe produced by anodic ionization 3+ The substances combine to form a sparingly soluble salt that adheres to the metal surface, forming a passivation film. This passivation film is chemically stable, preventing further electrochemical reactions on the metal surface and providing long-term protection against corrosion. It also enhances the pigment's corrosion resistance, thus protecting the inner metal layer. When other corrosive cations reach the surface of the mixed passivation layer, they undergo ion exchange reactions with the passivation layer material before corroding the inner metal, reducing the chance of corrosion. Furthermore, in the protection of the passivation layer, when corrosive cations attack the surface of the anti-rust pigment, Ca2+ reactions also occur. 2+ The exchange process simultaneously produces calcium-iron silicates, further enhancing the protective effect and improving the corrosion resistance of the passivation layer and the lifespan of the pigments.

[0013] S3. Preparation of hyperbranched polysiloxane: Mix silane coupling agent KH560 and glycerol, heat to react, and distill until the temperature of the distillate drops below 45°C, then stop distillation to obtain hyperbranched polysiloxane.

[0014] S4. Preparation of modified calcium ion silica pigment: Hyperbranched polysiloxane and calcium ion silica pigment are mixed, added to ethanol, heated and stirred to react, filtered, washed, ground, dried and sieved to obtain modified calcium ion silica pigment.

[0015] Hyperbranched polysiloxanes are prepared by reacting silane coupling agent KH560 with glycerol. Hyperbranched polymers have the characteristics of high branching degree, minimal chain-chain entanglement, a large number of active end groups, non-crystallization, low viscosity, and high chemical reactivity. On the one hand, they form a three-dimensional encapsulation on the pigment surface, reduce the amount of oil adsorbed by the pigment through steric hindrance, and improve its dispersibility in coatings. On the other hand, they can also improve the toughness of the resin.

[0016] S5. Preparation of ferric tripolyphosphate: Dissolve ferrous sulfate and hydrogen peroxide in water, adjust the pH value, let stand and age, filter, add phosphoric acid to the solid, heat to react, increase the temperature to react, cool to room temperature, filter, wash, and dry to obtain ferric tripolyphosphate.

[0017] S6. Preparation of modified ferric tripolyphosphate: Ferric tripolyphosphate was added to Tris-HCl solution, tannic acid was added, the mixture was heated and stirred to react, filtered, washed, ground, dried and sieved to obtain modified ferric tripolyphosphate.

[0018] Ferric tripolyphosphate is a white powder that is poorly soluble in water and has excellent rust-preventive properties, making it suitable as a rust-preventive pigment. This invention synthesizes ferric tripolyphosphate from ferrous sulfate and phosphoric acid via a high-temperature condensation reaction. This invention uses tannic acid to modify ferric tripolyphosphate. Tannic acid is a polyphenolic substance with good adhesion properties, containing a large number of -OH and -NH2 groups, which can be loaded onto the surface of inorganic materials through hydrogen bonding. Because it contains phenolic structures, it can bind with metal ions such as Fe. 3+ Coordination forms stable complexes, thus achieving good anti-corrosion and anti-rust effects. On the other hand, it can also improve the compatibility of inorganic pigments in coating systems. Thirdly, it can form a dense layer, blocking surface pores and reducing oil absorption.

[0019] S7. Preparation of low oil absorption rust and corrosion resistant powder: Fine powder of silica pigment, modified calcium ion silica pigment and modified iron tripolyphosphate are mixed evenly to obtain low oil absorption rust and corrosion resistant powder.

[0020] This invention uses pigments of different particle sizes (large, medium, and small) to prepare a low-oil-absorption rust-proof and corrosion-resistant powder. Through the particle size distribution structure, the material distribution around the pigment is improved, and small particles enter the gaps between large particles, which in turn reduces the gaps and greatly reduces the oil absorption. At the same time, the surface modification also reduces the agglomeration effect between pigments.

[0021] As a further improvement of the present invention, the mass ratio of nano-silica, calcium salt, and silane coupling agent in step S1 is 5-7:1-2:0.5-1, the silane coupling agent includes KH560 and KH550 with a mass ratio of 1:1-3, the heating and stirring reaction temperature is 60-90℃, the time is 60-90min, the sieve mesh size is 100 mesh, the average particle size of the nano-silica is 200-500nm, and the calcium salt is calcium chloride or calcium nitrate.

[0022] As a further improvement of the present invention, the volume ratio of sodium silicate solution to sulfuric acid solution in step S2 is 2-4:1, the concentration of SiO2 in the sodium silicate solution is 20-30wt%, the concentration of the sulfuric acid solution is 40-50wt%, the aging time is 2-4h, the heating temperature is 75-85℃, the calcium salt is calcium chloride or calcium nitrate, and the heating aging temperature is 90-95℃ for 3-5h.

[0023] As a further improvement of the present invention, the mass ratio of silane coupling agent KH560 and glycerol in step S3 is 10-12:8-10, and the heating reaction is as follows: in the first stage, the temperature is raised to 120-140°C and held for 30-60 minutes, and then the temperature is raised to 160°C to continue the reaction until distillation is carried out until the temperature of the distillate drops below 45°C.

[0024] As a further improvement of the present invention, the mass ratio of the hyperbranched polysiloxane and calcium ion silica pigment in step S4 is 2-3:10, and the heating and stirring reaction temperature is 50-60℃, and the time is 2-4h.

[0025] As a further improvement of the present invention, in step S5, the pH value is adjusted to 6-9, the mass ratio of ferrous sulfate, hydrogen peroxide and phosphoric acid is 1:3-5:1.1-1.3, the heating reaction temperature is 95-100℃ and the time is 0.5-1h, and the temperature of the temperature rise reaction is 300-350℃ and the time is 2-4h.

[0026] As a further improvement of the present invention, the pH value of the Tris-HCl solution in step S6 is 8.5-9.5, the mass ratio of ferric tripolyphosphate to tannic acid is 10:3-4, the temperature of the heating and stirring reaction is 45-55℃, and the time is 3-5h.

[0027] As a further improvement of the present invention, the mass ratio of the silica pigment powder, modified calcium ion silica pigment and modified iron tripolyphosphate in step S7 is 1-5:5-10:10-15.

[0028] This invention further protects a low-oil-absorption rust-preventive and corrosion-resistant powder prepared by the above-described preparation method.

[0029] The present invention has the following beneficial effects:

[0030] 1. This invention uses tannic acid to modify iron tripolyphosphate, which improves its compatibility in coatings and enhances the rust and corrosion resistance of coatings, while also reducing the oil absorption of pigments.

[0031] 2. The present invention uses nano-silica treated with calcium salt to improve its anti-corrosion and anti-rust properties. The surface is modified with a composite silane coupling agent to improve the wettability, compatibility and dispersibility of pigments in coatings and improve the mechanical properties of composite pigments.

[0032] 3. This invention uses hyperbranched polysiloxane-modified calcium ion silica pigments to reduce the amount of oil adsorbed by the pigments and improve their dispersibility in coatings. On the other hand, it can also improve the toughness of the resin.

[0033] 4. This invention adopts the principle of multi-level particle size distribution to improve the material distribution around the pigment. Small particles enter the gaps between large particles, which in turn reduces the gaps and greatly reduces the amount of oil absorbed. At the same time, the surface modification also reduces the agglomeration effect between pigments. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 The image shows the XRD pattern of ferric tripolyphosphate.

[0036] Figure 2 The images show a comparison of the corrosion of the test plates after the salt spray test of Examples 1-3 and Comparative Examples 1-4, and the zinc phosphate group. In the images, A represents Example 1, B represents Example 2, C represents Example 3, D represents Comparative Example 1, E represents Comparative Example 2, F represents Comparative Example 3, G represents Comparative Example 4, and H represents zinc phosphate. Detailed Implementation

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Example 1

[0039] This embodiment provides a method for preparing a low-oil-absorption rust-preventive and corrosion-resistant powder, including the following steps:

[0040] S1. Preparation of fine silica pigment powder: 5g of nano silica with an average particle size of 200-500nm, 1g of calcium chloride, and 0.5g of silane coupling agent were added to 30mL of water, heated to 60℃, stirred and reacted for 60min, filtered, washed, ground, dried, and passed through a 100-mesh sieve. Powder with a particle size below 100 mesh was collected to obtain fine silica pigment powder.

[0041] The silane coupling agent includes KH560 and KH550 in a mass ratio of 1:1.

[0042] S2. Preparation of calcium ion silica pigment: 20 mL of sodium silicate solution and 10 mL of sulfuric acid solution were mixed. The concentration of SiO2 in the sodium silicate solution was 20 wt%, and the concentration of the sulfuric acid solution was 40 wt%. The mixture was stirred for 15 min, aged for 2 h, crushed, and then 20 mL of water was added. The pH value was adjusted to 8.5-9, heated to 75 °C, stirred, and aged for 1 h. Then the pH value was adjusted to 5.5-6, filtered, washed, and dried. The solid was added to 20 mL of water, 1 g of calcium chloride was added, stirred and mixed, heated to 90 °C, aged for 3 h, filtered, washed, and dried to obtain calcium ion silica pigment.

[0043] S3. Preparation of hyperbranched polysiloxane: Mix 10g of silane coupling agent KH560 and 8g of glycerol, heat and distill, raise the temperature to 120℃, keep it at that temperature for 30min, continue to raise the temperature to 160℃ and continue the reaction until the temperature of the distillate drops below 45℃, then stop to obtain hyperbranched polysiloxane.

[0044] S4. Preparation of modified calcium ion silica pigment: 2g of hyperbranched polysiloxane and 10g of calcium ion silica pigment were mixed and added to 200mL of ethanol. The mixture was heated to 50℃ and stirred for 2h. After filtration, washing, grinding, drying, and passing through 40-mesh and 60-mesh sieves, the powder with a particle size between 40-mesh and 60-mesh was collected to obtain modified calcium ion silica pigment.

[0045] S5. Preparation of ferric tripolyphosphate: Dissolve 1g of ferrous sulfate and 3g of hydrogen peroxide in 20mL of water, adjust the pH to 6, let stand for 2h, filter, add 1.1g of phosphoric acid to the solid, heat to 95℃, keep the temperature for 0.5h, raise the temperature to 300℃, keep the temperature for 2h, cool to room temperature, filter, wash, and dry to obtain ferric tripolyphosphate. Figure 1 The XRD pattern of the prepared iron tripolyphosphate shows strong characteristic peaks at 22.92° and 25.89°.

[0046] S6. Preparation of modified ferric tripolyphosphate: 1g of ferric tripolyphosphate was added to 50mL of Tris-HCl solution (pH 8.5), 0.3g of tannic acid was added, the mixture was heated to 45℃, stirred and reacted for 3h, filtered, washed and ground, dried, and passed through 60-mesh and 100-mesh sieves. Powder with a particle size between 60-mesh and 100-mesh was collected to obtain modified ferric tripolyphosphate.

[0047] S7. Preparation of low oil absorption rust and corrosion resistant powder: Mix 1g of silica pigment fine powder, 5g of modified calcium ion silica pigment and 10g of modified tripolyphosphate evenly to obtain low oil absorption rust and corrosion resistant powder.

[0048] Example 2

[0049] This embodiment provides a method for preparing a low-oil-absorption rust-preventive and corrosion-resistant powder, including the following steps:

[0050] S1. Preparation of fine silica pigment powder: 7g of nano silica with an average particle size of 200-500nm, 2g of calcium nitrate, and 1g of silane coupling agent were added to 30mL of water, heated to 90℃, stirred and reacted for 90min, filtered, washed, ground, dried, and passed through a 100-mesh sieve. Powder with a particle size below 100mesh was collected to obtain fine silica pigment powder.

[0051] The silane coupling agent includes KH560 and KH550 in a mass ratio of 1:3.

[0052] S2. Preparation of calcium ion silica pigment: 40 mL of sodium silicate solution and 10 mL of sulfuric acid solution were mixed. The concentration of SiO2 in the sodium silicate solution was 30 wt%, and the concentration of the sulfuric acid solution was 50 wt%. The mixture was stirred for 15 min, aged for 4 h, crushed, and then 20 mL of water was added to adjust the pH to 8.5-9. The mixture was heated to 85 °C, stirred, and aged for 1 h. Then the pH was adjusted to 5.5-6, filtered, washed, and dried. The solid was added to 20 mL of water, and 1.5 g of calcium nitrate was added. The mixture was stirred and mixed, heated to 95 °C, and aged for 5 h. The mixture was filtered, washed, and dried to obtain calcium ion silica pigment.

[0053] S3. Preparation of hyperbranched polysiloxane: Mix 12g of silane coupling agent KH560 and 10g of glycerol, heat and distill, raise the temperature to 140℃, keep it at the temperature for 60min, continue to raise the temperature to 160℃ and continue the reaction until the temperature of the distillate drops below 45℃, then stop to obtain hyperbranched polysiloxane.

[0054] S4. Preparation of modified calcium ion silica pigment: 3g of hyperbranched polysiloxane and 10g of calcium ion silica pigment were mixed and added to 200mL of ethanol. The mixture was heated to 60℃ and stirred for 4h. After filtration, washing, grinding, drying, and passing through 40-mesh and 60-mesh sieves, the powder with a particle size between 40-mesh and 60-mesh was collected to obtain modified calcium ion silica pigment.

[0055] S5. Preparation of ferric tripolyphosphate: Dissolve 1g of ferrous sulfate and 5g of hydrogen peroxide in 20mL of water, adjust the pH to 9, let stand for 2h, filter, add 1.3g of phosphoric acid to the solid, heat to 100℃, keep the temperature for 1h, raise the temperature to 350℃, keep the temperature for 4h, cool to room temperature, filter, wash, and dry to obtain ferric tripolyphosphate.

[0056] S6. Preparation of modified ferric tripolyphosphate: 1g of ferric tripolyphosphate was added to 50mL of Tris-HCl solution (pH 9.5), 0.4g of tannic acid was added, the mixture was heated to 55℃, stirred and reacted for 5h, filtered, washed and ground, dried, and passed through 60-mesh and 100-mesh sieves. Powder with a particle size between 60-mesh and 100-mesh was collected to obtain modified ferric tripolyphosphate.

[0057] S7. Preparation of low oil absorption rust and corrosion prevention powder: Mix 5g of silica pigment fine powder, 10g of modified calcium ion silica pigment and 15g of modified iron tripolyphosphate evenly to obtain low oil absorption rust and corrosion prevention powder.

[0058] Example 3

[0059] This embodiment provides a method for preparing a low-oil-absorption rust-preventive and corrosion-resistant powder, including the following steps:

[0060] S1. Preparation of fine silica pigment powder: 6g of nano silica with an average particle size of 200-500nm, 1.5g of calcium nitrate, and 0.7g of silane coupling agent were added to 30mL of water, heated to 75℃, stirred and reacted for 75min, filtered, washed, ground, dried, and passed through a 100-mesh sieve. Powder with a particle size below 100 mesh was collected to obtain fine silica pigment powder.

[0061] The silane coupling agent includes KH560 and KH550 in a mass ratio of 1:2.

[0062] S2. Preparation of calcium ion silica pigment: 30 mL of sodium silicate solution and 10 mL of sulfuric acid solution were mixed. The concentration of SiO2 in the sodium silicate solution was 24.5 wt%, and the concentration of the sulfuric acid solution was 45 wt%. The mixture was stirred for 15 min, aged for 3 h, crushed, and then 20 mL of water was added to adjust the pH to 8.5-9. The mixture was heated to 80 °C, stirred, and aged for 1 h. Then the pH was adjusted to 5.5-6, filtered, washed, and dried. The solid was added to 20 mL of water, and 1.2 g of calcium nitrate was added. The mixture was stirred and mixed, heated to 92 °C, and aged for 4 h. The mixture was filtered, washed, and dried to obtain calcium ion silica pigment.

[0063] S3. Preparation of hyperbranched polysiloxane: Mix 11g of silane coupling agent KH560 and 9g of glycerol, heat and distill, raise the temperature to 130℃, keep it at the temperature for 45min, continue to raise the temperature to 160℃ and continue the reaction until the temperature of the distillate drops below 45℃, then stop to obtain hyperbranched polysiloxane.

[0064] S4. Preparation of modified calcium ion silica pigment: 2.5g of hyperbranched polysiloxane and 10g of calcium ion silica pigment were mixed and added to 200mL of ethanol. The mixture was heated to 55℃ and stirred for 3h. After filtration, washing, grinding, drying, and passing through 40-mesh and 60-mesh sieves, the powder with a particle size between 40-mesh and 60-mesh was collected to obtain modified calcium ion silica pigment.

[0065] S5. Preparation of ferric tripolyphosphate: Dissolve 1g of ferrous sulfate and 4g of hydrogen peroxide in 20mL of water, adjust the pH to 7.5, let stand for 2 hours, filter, add 1.2g of phosphoric acid to the solid, heat to 98℃, keep the temperature for 1 hour, raise the temperature to 320℃, keep the temperature for 3 hours, cool to room temperature, filter, wash, and dry to obtain ferric tripolyphosphate.

[0066] S6. Preparation of modified ferric tripolyphosphate: 1g of ferric tripolyphosphate was added to 50mL of Tris-HCl solution (pH 9), 0.35g of tannic acid was added, the mixture was heated to 50℃, stirred and reacted for 4h, filtered, washed and ground, dried, and passed through 60-mesh and 100-mesh sieves. Powder with a particle size between 60-mesh and 100-mesh was collected to obtain modified ferric tripolyphosphate.

[0067] S7. Preparation of low oil absorption rust and corrosion resistant powder: Mix 3g of fine silica pigment powder, 7g of modified calcium ion silica pigment and 12g of modified iron tripolyphosphate evenly to obtain low oil absorption rust and corrosion resistant powder.

[0068] Comparative Example 1

[0069] The difference from Example 3 is that no silane coupling agent was added in step S1.

[0070] Includes the following steps:

[0071] S1. Preparation of fine silica pigment powder: 6g of nano silica with an average particle size of 200-500nm and 1.5g of calcium nitrate were added to 30mL of water, heated to 75℃, stirred and reacted for 75min, filtered, washed, ground, dried, passed through a 100-mesh sieve, and the powder with a particle size of less than 100 mesh was collected to obtain fine silica pigment powder.

[0072] S2. Preparation of calcium ion silica pigment: 30 mL of sodium silicate solution and 10 mL of sulfuric acid solution were mixed. The concentration of SiO2 in the sodium silicate solution was 24.5 wt%, and the concentration of the sulfuric acid solution was 45 wt%. The mixture was stirred for 15 min, aged for 3 h, crushed, and then 20 mL of water was added to adjust the pH to 8.5-9. The mixture was heated to 80 °C, stirred, and aged for 1 h. Then the pH was adjusted to 5.5-6, filtered, washed, and dried. The solid was added to 20 mL of water, and 1.2 g of calcium nitrate was added. The mixture was stirred and mixed, heated to 92 °C, and aged for 4 h. The mixture was filtered, washed, and dried to obtain calcium ion silica pigment.

[0073] S3. Preparation of hyperbranched polysiloxane: Mix 11g of silane coupling agent KH560 and 9g of glycerol, heat and distill, raise the temperature to 130℃, keep it at the temperature for 45min, continue to raise the temperature to 160℃ and continue the reaction until the temperature of the distillate drops below 45℃, then stop to obtain hyperbranched polysiloxane.

[0074] S4. Preparation of modified calcium ion silica pigment: 2.5g of hyperbranched polysiloxane and 10g of calcium ion silica pigment were mixed and added to 200mL of ethanol. The mixture was heated to 55℃ and stirred for 3h. After filtration, washing, grinding, drying, and passing through 40-mesh and 60-mesh sieves, the powder with a particle size between 40-mesh and 60-mesh was collected to obtain modified calcium ion silica pigment.

[0075] S5. Preparation of ferric tripolyphosphate: Dissolve 1g of ferrous sulfate and 4g of hydrogen peroxide in 20mL of water, adjust the pH to 7.5, let stand for 2 hours, filter, add 1.2g of phosphoric acid to the solid, heat to 98℃, keep the temperature for 1 hour, raise the temperature to 320℃, keep the temperature for 3 hours, cool to room temperature, filter, wash, and dry to obtain ferric tripolyphosphate.

[0076] S6. Preparation of modified ferric tripolyphosphate: 1g of ferric tripolyphosphate was added to 50mL of Tris-HCl solution (pH 9), 0.35g of tannic acid was added, the mixture was heated to 50℃, stirred and reacted for 4h, filtered, washed and ground, dried, and passed through 60-mesh and 100-mesh sieves. Powder with a particle size between 60-mesh and 100-mesh was collected to obtain modified ferric tripolyphosphate.

[0077] S7. Preparation of low oil absorption rust and corrosion resistant powder: Mix 3g of fine silica pigment powder, 7g of modified calcium ion silica pigment and 12g of modified iron tripolyphosphate evenly to obtain low oil absorption rust and corrosion resistant powder.

[0078] Comparative Example 2

[0079] The difference from Example 3 is that steps S3 and S4 in Example 3 were not performed.

[0080] Includes the following steps:

[0081] S1. Preparation of fine silica pigment powder: 6g of nano silica with an average particle size of 200-500nm, 1.5g of calcium nitrate, and 0.7g of silane coupling agent were added to 30mL of water, heated to 75℃, stirred and reacted for 75min, filtered, washed, ground, dried, and passed through a 100-mesh sieve. Powder with a particle size below 100 mesh was collected to obtain fine silica pigment powder.

[0082] The silane coupling agent includes KH560 and KH550 in a mass ratio of 1:2.

[0083] S2. Preparation of calcium ion silica pigment: 30 mL of sodium silicate solution and 10 mL of sulfuric acid solution were mixed. The concentration of SiO2 in the sodium silicate solution was 24.5 wt%, and the concentration of the sulfuric acid solution was 45 wt%. The mixture was stirred for 15 min, aged for 3 h, crushed, and then 20 mL of water was added to adjust the pH to 8.5-9. The mixture was heated to 80 °C, stirred, and aged for 1 h. Then the pH was adjusted to 5.5-6, filtered, washed, and dried. The solid was added to 20 mL of water, and 1.2 g of calcium nitrate was added. The mixture was stirred and mixed, heated to 92 °C, and aged for 4 h. The mixture was filtered, washed, and dried to obtain calcium ion silica pigment.

[0084] S3. Preparation of ferric tripolyphosphate: Dissolve 1g of ferrous sulfate and 4g of hydrogen peroxide in 20mL of water, adjust the pH to 7.5, let stand for 2 hours, filter, add 1.2g of phosphoric acid to the solid, heat to 98℃, keep the temperature for 1 hour, raise the temperature to 320℃, keep the temperature for 3 hours, cool to room temperature, filter, wash, and dry to obtain ferric tripolyphosphate.

[0085] S4. Preparation of modified ferric tripolyphosphate: Add 1g of ferric tripolyphosphate to 50mL of Tris-HCl solution (pH 9), add 0.35g of tannic acid, heat to 50℃, stir and react for 4h, filter, wash and grind, dry, pass through 60 mesh and 100 mesh sieves, collect powder with particle size between 60 mesh and 100 mesh to obtain modified ferric tripolyphosphate.

[0086] S5. Preparation of low oil absorption rust and corrosion prevention powder: Mix 3g of silica pigment fine powder, 7g of calcium ion silica pigment and 12g of modified iron tripolyphosphate evenly to obtain low oil absorption rust and corrosion prevention powder.

[0087] Comparative Example 3

[0088] The difference from Example 3 is that step S6 in Example 3 was not performed.

[0089] Includes the following steps:

[0090] S1. Preparation of fine silica pigment powder: 6g of nano silica with an average particle size of 200-500nm, 1.5g of calcium nitrate, and 0.7g of silane coupling agent were added to 30mL of water, heated to 75℃, stirred and reacted for 75min, filtered, washed, ground, dried, and passed through a 100-mesh sieve. Powder with a particle size below 100 mesh was collected to obtain fine silica pigment powder.

[0091] The silane coupling agent includes KH560 and KH550 in a mass ratio of 1:2.

[0092] S2. Preparation of calcium ion silica pigment: 30 mL of sodium silicate solution and 10 mL of sulfuric acid solution were mixed. The concentration of SiO2 in the sodium silicate solution was 24.5 wt%, and the concentration of the sulfuric acid solution was 45 wt%. The mixture was stirred for 15 min, aged for 3 h, crushed, and then 20 mL of water was added to adjust the pH to 8.5-9. The mixture was heated to 80 °C, stirred, and aged for 1 h. Then the pH was adjusted to 5.5-6, filtered, washed, and dried. The solid was added to 20 mL of water, and 1.2 g of calcium nitrate was added. The mixture was stirred and mixed, heated to 92 °C, and aged for 4 h. The mixture was filtered, washed, and dried to obtain calcium ion silica pigment.

[0093] S3. Preparation of hyperbranched polysiloxane: Mix 11g of silane coupling agent KH560 and 9g of glycerol, heat and distill, raise the temperature to 130℃, keep it at the temperature for 45min, continue to raise the temperature to 160℃ and continue the reaction until the temperature of the distillate drops below 45℃, then stop to obtain hyperbranched polysiloxane.

[0094] S4. Preparation of modified calcium ion silica pigment: 2.5g of hyperbranched polysiloxane and 10g of calcium ion silica pigment were mixed and added to 200mL of ethanol. The mixture was heated to 55℃ and stirred for 3h. After filtration, washing, grinding, drying, and passing through 40-mesh and 60-mesh sieves, the powder with a particle size between 40-mesh and 60-mesh was collected to obtain modified calcium ion silica pigment.

[0095] S5. Preparation of ferric tripolyphosphate: Dissolve 1g of ferrous sulfate and 4g of hydrogen peroxide in 20mL of water, adjust the pH to 7.5, let stand for 2 hours, filter, add 1.2g of phosphoric acid to the solid, heat to 98℃, keep the temperature for 1 hour, raise the temperature to 320℃, keep the temperature for 3 hours, cool to room temperature, filter, wash, and dry to obtain ferric tripolyphosphate.

[0096] S6. Preparation of low oil absorption rust and corrosion prevention powder: Mix 3g of fine silica pigment powder, 7g of modified calcium ion silica pigment and 12g of ferric tripolyphosphate evenly to obtain low oil absorption rust and corrosion prevention powder.

[0097] Comparative Example 4

[0098] The difference from Example 3 is that no sieving was performed in steps S1, S4 and S6.

[0099] Includes the following steps:

[0100] S1. Preparation of silica pigment fine powder: 6g of nano silica with an average particle size of 200-500nm, 1.5g of calcium nitrate and 0.7g of silane coupling agent were added to 30mL of water, heated to 75℃, stirred and reacted for 75min, filtered, washed, ground and dried to obtain silica pigment fine powder.

[0101] The silane coupling agent includes KH560 and KH550 in a mass ratio of 1:2.

[0102] S2. Preparation of calcium ion silica pigment: 30 mL of sodium silicate solution and 10 mL of sulfuric acid solution were mixed. The concentration of SiO2 in the sodium silicate solution was 24.5 wt%, and the concentration of the sulfuric acid solution was 45 wt%. The mixture was stirred for 15 min, aged for 3 h, crushed, and then 20 mL of water was added to adjust the pH to 8.5-9. The mixture was heated to 80 °C, stirred, and aged for 1 h. Then the pH was adjusted to 5.5-6, filtered, washed, and dried. The solid was added to 20 mL of water, and 1.2 g of calcium nitrate was added. The mixture was stirred and mixed, heated to 92 °C, and aged for 4 h. The mixture was filtered, washed, and dried to obtain calcium ion silica pigment.

[0103] S3. Preparation of hyperbranched polysiloxane: Mix 11g of silane coupling agent KH560 and 9g of glycerol, heat and distill, raise the temperature to 130℃, keep it at the temperature for 45min, continue to raise the temperature to 160℃ and continue the reaction until the temperature of the distillate drops below 45℃, then stop to obtain hyperbranched polysiloxane.

[0104] S4. Preparation of modified calcium ion silica pigment: 2.5g of hyperbranched polysiloxane and 10g of calcium ion silica pigment were mixed and added to 200mL of ethanol. The mixture was heated to 55℃ and stirred for 3h. The mixture was then filtered, washed, ground, and dried to obtain the modified calcium ion silica pigment.

[0105] S5. Preparation of ferric tripolyphosphate: Dissolve 1g of ferrous sulfate and 4g of hydrogen peroxide in 20mL of water, adjust the pH to 7.5, let stand for 2 hours, filter, add 1.2g of phosphoric acid to the solid, heat to 98℃, keep the temperature for 1 hour, raise the temperature to 320℃, keep the temperature for 3 hours, cool to room temperature, filter, wash, and dry to obtain ferric tripolyphosphate.

[0106] S6. Preparation of modified ferric tripolyphosphate: 1g of ferric tripolyphosphate was added to 50mL of Tris-HCl solution (pH 9), 0.35g of tannic acid was added, the mixture was heated to 50℃, stirred for 4h, filtered, washed, ground and dried to obtain modified ferric tripolyphosphate.

[0107] S7. Preparation of low oil absorption rust and corrosion resistant powder: Mix 3g of fine silica pigment powder, 7g of modified calcium ion silica pigment and 12g of modified iron tripolyphosphate evenly to obtain low oil absorption rust and corrosion resistant powder.

[0108] Test Example 1

[0109] The oil absorption of the low oil absorption rust-proof and corrosion-resistant powders prepared in Examples 1-3 and Comparative Examples 1-4, as well as commercially available calcium ion silica pigments, was determined according to GB 5211.15-2014 "Determination of Oil Absorption of Pigments". The results are shown in Table 1.

[0110] Table 1

[0111]

[0112] As can be seen from the table above, the low oil absorption rust and corrosion prevention powders prepared in Examples 1-3 of the present invention have low oil absorption.

[0113] Test Example 2

[0114] The low oil absorption rust-preventing and anti-corrosion powders obtained in Examples 1-3 and Comparative Examples 1-4 were used as rust-preventing pigments (with zinc phosphate as a comparison) to prepare epoxy resin coatings with epoxy resin 601, dispersant AT204, anti-settling agent 3300S, xylene, filler, and cashew shell epoxy curing agent, and their performance was tested.

[0115] The basic formulation of component A of epoxy resin coating is shown in Table 2 below.

[0116] Table 2. Parts by weight

[0117]

[0118] Preparation method: Mix all components evenly, filter, and obtain epoxy resin coating component A.

[0119] Component B of epoxy resin coating: Cashew shell epoxy curing agent.

[0120] Coating preparation method: The epoxy resin coating component A and epoxy resin coating component B are mixed evenly at a volume ratio of 7:1 to obtain the epoxy coating product. After curing for 10 minutes, the product is filtered, and 15 wt% organic solvent-based epoxy thinner is added to adjust the spraying viscosity. The coating is then sprayed onto the board. After spraying, the test board is leveled for about 15 minutes and then placed in a constant temperature room (temperature 25℃, relative humidity 50%) for curing for 7 days before testing.

[0121] The adhesion of the paint film was tested according to GB / T9286-2021 "Cross-cut test for paints and varnishes".

[0122] The flexibility of the paint film was tested according to GB / T6742-2007 "Paints and Varnishes - Bending Test (Cylindrical Shaft)".

[0123] The impact resistance of coatings is tested using a paint film impact tester according to GB / T1732-2020 "Test Method for Impact Resistance of Paint Films".

[0124] The resistance to liquid media is tested according to Method A of GB9274-1988 "Determination of Resistance of Paints and Varnishes to Liquid Media". The acid resistance is tested with 10% H2SO4 solution, the alkali resistance with 10% NaOH solution, and the salt resistance with 5% NaCl solution. The test ends when the paint film shows blistering, rusting, or severe discoloration. Slight discoloration is allowed.

[0125] According to GB / T1771-2007 "Determination of resistance to neutral salt spray of paints and varnishes", the salt spray resistance of the coating is tested, and the end time is when the unidirectional erosion at the scratched part of the paint film is >2.0mm, and the unscratched part shows blistering, rusting, peeling or cracking.

[0126] The results are shown in Table 3.

[0127] Table 3

[0128]

[0129] As shown in the table above, the coatings prepared by blending the low oil absorption rust-proof and corrosion-resistant powders obtained in Examples 1-3 of this invention exhibit good overall performance. The corrosion conditions of the test plates after salt spray testing of Examples 1-3 and Comparative Examples 1-4, and the zinc phosphate group are as follows: Figure 2 As shown, A is Example 1, B is Example 2, C is Example 3, D is Comparative Example 1, E is Comparative Example 2, F is Comparative Example 3, G is Comparative Example 4, and H is Zinc Phosphate.

[0130] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a low-oil-absorption rust-preventive and corrosion-resistant powder, characterized in that, Nano-silica was modified with calcium salt and silane coupling agent to obtain fine silica pigment powder; calcium ion silica pigment was modified with hyperbranched polysiloxane to obtain modified calcium ion silica pigment; iron tripolyphosphate was modified with tannic acid to obtain modified iron tripolyphosphate, and these were mixed evenly with fine silica pigment powder and modified calcium ion silica pigment to obtain a low oil absorption rust and corrosion resistant powder.

2. The preparation method according to claim 1, characterized in that, Includes the following steps: S1. Preparation of fine silica pigment powder: Nano silica, calcium salt, and silane coupling agent are added to water, heated and stirred to react, filtered, washed, ground, dried, and sieved to obtain fine silica pigment powder; S2. Preparation of calcium ion silica pigment: Sodium silicate solution and sulfuric acid solution are mixed, stirred and reacted, aged, crushed and then water is added, the pH value is adjusted to 8.5-9, heated and stirred, kept at the temperature for aging, then the pH value is adjusted to 5.5-6, filtered, washed and dried, the solid is added to water, calcium salt is added, stirred and mixed, heated and aged, filtered, washed and dried to obtain calcium ion silica pigment; S3. Preparation of hyperbranched polysiloxane: Mix silane coupling agent KH560 and glycerol, heat to react, and distill until the temperature of the distillate drops below 45°C, then stop distillation to obtain hyperbranched polysiloxane; S4. Preparation of modified calcium ion silica pigment: Hyperbranched polysiloxane and calcium ion silica pigment are mixed, added to ethanol, heated and stirred to react, filtered, washed, ground, dried and sieved to obtain modified calcium ion silica pigment; S5. Preparation of ferric tripolyphosphate: Dissolve ferrous sulfate and hydrogen peroxide in water, adjust the pH value, let stand and age, filter, add phosphoric acid to the solid, heat to react, increase the temperature to react, cool to room temperature, filter, wash, and dry to obtain ferric tripolyphosphate. S6. Preparation of modified ferric tripolyphosphate: Ferric tripolyphosphate was added to Tris-HCl solution, tannic acid was added, the mixture was heated and stirred to react, filtered, washed, ground, dried and sieved to obtain modified ferric tripolyphosphate; S7. Preparation of low oil absorption rust and corrosion resistant powder: Fine powder of silica pigment, modified calcium ion silica pigment and modified iron tripolyphosphate are mixed evenly to obtain low oil absorption rust and corrosion resistant powder.

3. The preparation method according to claim 2, characterized in that, In step S1, the mass ratio of nano-silica, calcium salt, and silane coupling agent is 5-7:1-2:0.5-1. The silane coupling agent includes KH560 and KH550, with a mass ratio of 1:1-3. The heating and stirring reaction temperature is 60-90℃, and the time is 60-90 min. The sieve mesh size is 100 mesh. The average particle size of the nano-silica is 200-500 nm. The calcium salt is calcium chloride or calcium nitrate.

4. The preparation method according to claim 2, characterized in that, In step S2, the volume ratio of sodium silicate solution to sulfuric acid solution is 2-4:1, the concentration of SiO2 in the sodium silicate solution is 20-30 wt%, the concentration of sulfuric acid solution is 40-50 wt%, the aging time is 2-4 hours, the heating temperature is 75-85°C, the calcium salt is calcium chloride or calcium nitrate, and the heating aging temperature is 90-95°C for 3-5 hours.

5. The preparation method according to claim 2, characterized in that, In step S3, the mass ratio of silane coupling agent KH560 to glycerol is 10-12:8-10. The heating reaction is as follows: in the first stage, the temperature is raised to 120-140℃ and held for 30-60 minutes, then the temperature is raised to 160℃ and the reaction continues until distillation is carried out until the temperature of the distillate drops below 45℃.

6. The preparation method according to claim 2, characterized in that, In step S4, the mass ratio of the hyperbranched polysiloxane to the calcium ion silica pigment is 2-3:10, and the heating and stirring reaction temperature is 50-60℃ for 2-4 hours.

7. The preparation method according to claim 2, characterized in that, In step S5, the pH value is adjusted to 6-9, the mass ratio of ferrous sulfate, hydrogen peroxide, and phosphoric acid is 1:3-5:1.1-1.3, the heating reaction temperature is 95-100℃ and the time is 0.5-1h, and the temperature of the temperature rise reaction is 300-350℃ and the time is 2-4h.

8. The preparation method according to claim 2, characterized in that, In step S6, the pH value of the Tris-HCl solution is 8.5-9.5, the mass ratio of ferric tripolyphosphate to tannic acid is 10:3-4, the temperature of the heating and stirring reaction is 45-55℃, and the time is 3-5h.

9. The preparation method according to claim 2, characterized in that, The mass ratio of the silica pigment powder, modified calcium ion silica pigment, and modified iron tripolyphosphate in step S7 is 1-5:5-10:10-15.

10. A low-oil-absorption rust-preventive and corrosion-resistant powder prepared by the preparation method according to any one of claims 1-9.

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