Water-based rust preventive for metal materials, and preparation method and application thereof

Abstract

The application discloses a water-based rust inhibitor suitable for metal materials and a preparation method and application thereof, and belongs to the technical field of metal material surface treatment. The water-based rust inhibitor comprises the following components in percentage by mass: triethanolamine-dodecanedioic acid salt 15-20%, sodium molybdate 0.5-0.8%, borax 1.5-3%, D-sodium gluconate 0.3-1%, pure water 77.2-81%, and the adding amount of polyether modified defoaming agent is such that the concentration of the water-based rust inhibitor reaches 0.05-0.1 g / L. The organic adsorption type rust prevention system (triethanolamine-dodecanedioic acid salt) is combined with the inorganic passivation type rust prevention system (sodium molybdate and borax), and D-sodium gluconate is introduced as a synergistic corrosion inhibitor, so that the defects of poor rust prevention performance of a single system, easy failure in high-hardness water or easy induction of pitting corrosion are effectively overcome, the rust prevention performance is improved, and meanwhile, the formula is green and environment-friendly and does not cause pollution.

Description

Technical Field

[0001] This invention belongs to the field of metal material surface treatment technology, specifically relating to a water-based rust inhibitor suitable for metal materials, its preparation method, and its application. Background Technology

[0002] Metal materials are highly susceptible to corrosion during processing, storage, and transportation, thus requiring the use of rust inhibitors for protection. Existing publicly available water-based rust prevention systems mainly fall into two technical categories: one is an adsorption-type rust prevention system based on long-chain dicarboxylic acid organic amine salts. This type of formulation offers advantages such as good water solubility and excellent film-forming lubrication, but generally suffers from poor salt spray performance and is prone to failure in high-hardness water environments, failing to meet the rust prevention requirements of long-cycle inter-process operations. The other is an inorganic passivation-type rust prevention system based on sodium molybdate and borax. This type of formulation offers advantages such as a dense passivation film and strong resistance to pitting corrosion, but suffers from slow film formation and a sharp drop in corrosion inhibition efficiency at low concentrations. When used alone, it easily forms localized pitting corrosion on the metal surface, affecting the subsequent processing accuracy of the workpiece. Furthermore, while traditional rust inhibitors containing nitrites and phosphorus bases offer good rust prevention, they cause serious environmental pollution.

[0003] Therefore, there is an urgent need to develop a new, efficient, and environmentally friendly water-based rust inhibitor. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a water-based rust inhibitor suitable for metal materials, its preparation method and application. It combines the advantages of organic adsorption type and inorganic passivation type rust inhibitor system, and has excellent rust prevention performance and is green and environmentally friendly.

[0005] To achieve the above objective, the present invention adopts the following technical solution: a water-based rust inhibitor suitable for metal materials, the water-based rust inhibitor comprising the following components: by mass percentage, 15%–20% triethanolamine-dodecanoate, 0.5%–0.8% sodium molybdate, 1.5%–3% borax, 0.3%–1% sodium D-gluconate, and the balance being pure water; wherein, based on the total volume of the water-based rust inhibitor, an additional polyether-modified defoamer with a concentration of 0.05–0.1 g / L is added.

[0006] Preferably, the water-based rust inhibitor of the present invention comprises the following components: by mass percentage, 15% triethanolamine-dodecanoate, 0.8% sodium molybdate, 2.2% borax, 1% sodium D-gluconate, and 81% pure water; wherein, based on the total volume of the water-based rust inhibitor, an additional polyether-modified defoamer with a concentration of 0.05 g / L is added.

[0007] Preferably, the water-based rust inhibitor of the present invention comprises the following components: 20% triethanolamine-dodecanoate, 0.5% sodium molybdate, 1.5% borax, 0.8% sodium D-gluconate, and 77.2% pure water; wherein, based on the total volume of the water-based rust inhibitor, a polyether-modified defoamer with a concentration of 0.07 g / L is additionally added.

[0008] Preferably, the water-based rust inhibitor of the present invention comprises the following components: 15% triethanolamine-dodecanoate, 0.7% sodium molybdate, 3% borax, 0.3% sodium D-gluconate, and 81% pure water; wherein, based on the total volume of the water-based rust inhibitor, a polyether-modified defoamer with a concentration of 0.1 g / L is additionally added.

[0009] More preferably, the triethanolamine-dodecanoate of the present invention is prepared by neutralization reaction of triethanolamine and dodecanoic acid, wherein the amount of dodecanoic acid added is 30% to 50% of the mass of triethanolamine.

[0010] To achieve the other objective mentioned above, the present invention adopts the following technical solution: a method for preparing a water-based rust inhibitor suitable for metal materials, comprising the following steps: (1) Neutralization to form salt: Triethanolamine was heated, and then dodecanoic acid was added in batches. The mixture was stirred thoroughly and cooled to obtain triethanolamine-dodecanoic acid salt. (2) Compound preparation steps: Take the triethanolamine-dodecanoate obtained in step (1), add it to pure water and stir until it is evenly dissolved. Then add sodium molybdate, borax and D-gluconate in sequence and stir until they are evenly dissolved. Finally, add polyether modified defoamer and stir evenly to obtain the water-based rust inhibitor.

[0011] Preferably, in step 1) of the present invention, the heating temperature is 50-80°C, the stirring time is 2-3 hours, and the amount of dodecanoic acid added is 30%-50% of the mass of triethanolamine.

[0012] To achieve the above-mentioned objective, the present invention adopts the following technical solution: the application of a water-based rust inhibitor in the rust prevention treatment of metal materials, the specific application method being: immersing the metal part to be treated in the water-based rust inhibitor for 5 to 30 minutes and then air-drying it naturally, or uniformly applying the water-based rust inhibitor to the metal part to be treated and then air-drying it naturally.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) This invention creatively combines an organic adsorption-type rust-preventive system (triethanolamine-dodecanoate) with an inorganic passivation-type rust-preventive system (sodium molybdate, borax). The organic salts can rapidly form a hydrophobic adsorption film on the metal surface, providing immediate protection; while the inorganic salts can slowly form a dense passivation film, providing long-term protection. The synergistic effect of the two overcomes the shortcomings of single systems, such as poor salt spray performance or easy induction of pitting corrosion, and significantly improves the overall rust-preventive performance.

[0014] 2) This invention eliminates traditional toxic and harmful substances such as nitrites and phosphorus compounds. All components are environmentally friendly materials, which meet the requirements of modern industry for green manufacturing.

[0015] 3) This invention introduces sodium D-gluconate as a synergistic corrosion inhibitor, which can further stabilize the metal surface state; sodium D-gluconate can complex metal ions in hard water to avoid precipitation and affect rust prevention performance, thereby improving corrosion inhibition efficiency in high hard water.

[0016] 4) The addition of polyether modified defoamer ensures the stability of the product during production and use, and avoids foam from affecting the film quality. Detailed Implementation

[0017] The present invention will be further described below with reference to embodiments and comparative examples, but the scope of protection of the present invention is not limited thereto.

[0018] Example 1 A water-based rust inhibitor, the preparation method of which is as follows: (1) Neutralization to form salt: Take triethanolamine, heat it to 60°C, add 30% of the mass of triethanolamine dodecanoic acid in batches under stirring, keep warm and stir for 2 hours, cool and set aside to obtain triethanolamine-dodecanoic acid salt.

[0019] (2) Compounding: Take 15% of the triethanolamine-dodecanoate prepared above (the mass percentage of the total water-based rust inhibitor, the same below), add 81% pure water, and stir for 1 hour until it is evenly dissolved. Then add 0.8% sodium molybdate, 2.2% borax, and 1% D-gluconate in sequence, and stir for 2 hours until it is evenly dissolved. Finally, add polyether modified defoamer (the defoamer is BL-100 type defoamer purchased from Suzhou Beston Chemical Co., Ltd.) until the concentration reaches 0.05 g / L, and continue stirring for 1 hour to obtain the finished water-based rust inhibitor.

[0020] Instructions for use: Immerse the metal parts to be treated in the above water-based rust inhibitor, remove them after 10 minutes, and let them air dry naturally.

[0021] Example 2 A water-based rust inhibitor, the preparation method of which is as follows: (1) Neutralization to form salt: Take triethanolamine, heat it to 50°C, add 40% of the mass of triethanolamine dodecanoic acid in batches under stirring, keep warm and stir for 3 hours, cool and set aside to obtain triethanolamine-dodecanoic acid salt.

[0022] (2) Compounding: Take 20% of the triethanolamine-dodecanoate prepared above, add 77.2% pure water, and stir for 1 hour until it is evenly dissolved. Then add 0.5% sodium molybdate, 1.5% borax, and 0.8% sodium D-gluconate in sequence, and stir for 2 hours until it is evenly dissolved. Finally, add polyether modified defoamer until the concentration reaches 0.07 g / L, and continue stirring for 1 hour to obtain the water-based rust inhibitor product.

[0023] Instructions for use: Immerse the metal parts to be treated in the above water-based rust inhibitor, remove them after 5 minutes, and let them air dry naturally.

[0024] Example 3 A water-based rust inhibitor, the preparation method of which is as follows: (1) Neutralization to form salt: Take triethanolamine, heat it to 80°C, add 50% of the mass of triethanolamine dodecanoic acid in batches under stirring, keep warm and stir for 3 hours, cool and set aside to obtain triethanolamine-dodecanoic acid salt.

[0025] (2) Compounding: Take 15% of the triethanolamine-dodecanoate prepared above, add 81% pure water, and stir for 1 hour until it is evenly dissolved. Then add 0.7% sodium molybdate, 3% borax, and 0.3% sodium D-gluconate in sequence, and stir for 3 hours until it is evenly dissolved. Finally, add polyether modified defoamer until the concentration reaches 0.1 g / L, and continue stirring for 1 hour to obtain the water-based rust inhibitor product.

[0026] Instructions for use: Immerse the metal parts to be treated in the above water-based rust inhibitor, remove them after 30 minutes, and let them air dry naturally.

[0027] Example 4 A water-based rust inhibitor, the preparation method of which is as follows: (1) Neutralization to form salt: Take triethanolamine, heat it to 60°C, add 30% of the mass of triethanolamine dodecanoic acid in batches under stirring, keep warm and stir for 2 hours, cool and set aside to obtain triethanolamine-dodecanoic acid salt.

[0028] (2) Compounding: Take 15% of the triethanolamine-dodecanoate prepared above, add 81% of 1000ppm hard water, and stir for 1 hour until dissolved evenly. Then add 0.8% sodium molybdate, 2.2% borax, and 1% D-gluconate in sequence, and stir for 2 hours until dissolved evenly. Finally, add polyether modified defoamer until the concentration reaches 0.05g / L, and continue stirring for 1 hour to obtain the water-based rust inhibitor product.

[0029] Instructions for use: Immerse the metal parts to be treated in the above water-based rust inhibitor, remove them after 20 minutes, and let them air dry naturally.

[0030] Example 5 The difference from Example 1 is that, in this case, the water-based rust inhibitor is evenly applied to the metal part to be treated and allowed to air dry naturally. The remaining steps and component contents are the same as in Example 1.

[0031] Comparative Example 1 The difference from Example 3 is that the amount of dodecanoic acid added in the neutralization and salt formation step is 80% of the mass of triethanolamine. The remaining steps and component contents are the same as in Example 3.

[0032] Comparative Example 2 The difference from Example 2 is that the amount of sodium molybdate and borax added in the compounding step is 3% each. The remaining steps and component contents are the same as in Example 2.

[0033] Comparative Example 3 The difference from Example 2 is that sodium molybdate is not added in the compounding step. The remaining steps and component contents are the same as in Example 2.

[0034] Comparative Example 4 A rust inhibitor that does not contain triethanolamine-dodecanoate. Its composition is: 1% sodium molybdate, 4% borax, 0.8% sodium D-gluconate, with the balance being pure water, and finally a polyether-modified defoamer is added to a concentration of 0.02 g / L.

[0035] Comparative Example 5 The difference from Example 4 is that sodium D-gluconate is not added in the compounding step. The remaining steps and component contents are the same as in Example 4, and a small amount of white flocculent precipitate is produced after preparation.

[0036] Performance testing: The standard metal test pieces were treated with the rust inhibitors prepared in the above examples and comparative examples, respectively. After natural air drying, they were subjected to a 72-hour neutral salt spray test at 35±2℃ according to GB / T 10125-2021. Parallel experiments were also conducted using the standard metal test pieces. After 72 hours, the test pieces were cleaned and dried, and the corrosion inhibition rate was calculated based on the change in mass. The results are shown in Table 1 below: Table 1

[0037] As shown in the table above, Examples 1-5 of the present invention all exhibit excellent rust-preventive performance, with corrosion inhibition rates all exceeding 92%. In contrast, the rust-preventive performance of Comparative Examples 1 (inappropriate organic salt ratio), 2 (inappropriate inorganic salt ratio), 3 (lacking sodium molybdate), 4 (lacking organic salt), and 5 (lacking synergistic corrosion inhibitor) all showed a significant decrease. This demonstrates the necessity and superiority of the synergistic effect of the components in the present invention.

Claims

1. A water-based rust inhibitor suitable for metallic materials, characterized in that: The water-based rust inhibitor comprises the following components by mass percentage: 15%–20% triethanolamine-dodecanoate, 0.5%–0.8% sodium molybdate, 1.5%–3% borax, 0.3%–1% sodium D-gluconate, and the balance being pure water; wherein, based on the total volume of the water-based rust inhibitor, an additional polyether-modified defoamer with a concentration of 0.05–0.1 g / L is added.

2. The water-based rust inhibitor according to claim 1, characterized in that: The water-based rust inhibitor comprises the following components by mass percentage: 15% triethanolamine-dodecanoate, 0.8% sodium molybdate, 2.2% borax, 1% sodium D-gluconate, and 81% pure water; wherein, based on the total volume of the water-based rust inhibitor, an additional 0.05 g / L polyether-modified defoamer is added.

3. The water-based rust inhibitor according to claim 1, characterized in that: The water-based rust inhibitor comprises the following components: 20% triethanolamine-dodecanoate, 0.5% sodium molybdate, 1.5% borax, 0.8% sodium D-gluconate, and 77.2% pure water; wherein, based on the total volume of the water-based rust inhibitor, an additional 0.07 g / L polyether-modified defoamer is added.

4. The water-based rust inhibitor according to claim 1, characterized in that: The water-based rust inhibitor comprises the following components: 15% triethanolamine-dodecanoate, 0.7% sodium molybdate, 3% borax, 0.3% sodium D-gluconate, and 81% pure water; wherein, based on the total volume of the water-based rust inhibitor, an additional 0.1 g / L polyether-modified defoamer is added.

5. The water-based rust inhibitor according to any one of claims 1-4, characterized in that: The triethanolamine-dodecanoate is prepared by neutralization reaction of triethanolamine and dodecanoic acid, wherein the amount of dodecanoic acid added is 30% to 50% of the mass of triethanolamine.

6. A method for preparing the water-based rust inhibitor as described in any one of claims 1-4, characterized in that: The preparation steps are as follows: 1) Neutralization to salt formation step: Triethanolamine was heated, and then dodecanoic acid was added in batches. The mixture was stirred thoroughly and cooled to obtain triethanolamine-dodecanoic acid salt. 2) Compound preparation steps: Take the triethanolamine-dodecanoate obtained in step 1), add it to pure water and stir until it is evenly dissolved. Then add sodium molybdate, borax and sodium D-gluconate in sequence and stir until they are evenly dissolved. Finally, add polyether modified defoamer and stir evenly to obtain the water-based rust inhibitor.

7. The preparation method according to claim 6, characterized in that: In step 1), the heating temperature is 50-80°C, the stirring time is 2-3 hours, and the amount of dodecanoic acid added is 30%-50% of the mass of triethanolamine.

8. An application of the water-based rust inhibitor as described in any one of claims 1-4 in the rust prevention treatment of metal materials, wherein the specific application method is as follows: immersing the metal part to be treated in the water-based rust inhibitor for 5-30 minutes and then air-drying it naturally, or uniformly applying the water-based rust inhibitor to the metal part to be treated and then air-drying it naturally.

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