Metal rust-proof packaging

Vapor phase inhibitors can quickly evaporate at room temperature and fill the Packaging space, adsorbed on the metal surface, and play a role in preventing corrosion of metal corrosion. With the advantages of saving resources, reducing labor, opening and using, and beautifying packaging, it is widely used in military, machinery, aviation, shipbuilding, instrumentation, automobiles, measuring instruments, precision instruments, and medical devices. As an effective chemical component of vapour-phase rust-proof paper, nitrite-based corrosion inhibitors have been widely used at home and abroad due to their long-term effective rust-preventing ability and excellent salt spray resistance to steel products. However, nitroso and secondary amines are easy to synthesize nitrosamines in the human body, forming a strong carcinogen, and its toxicity has attracted people's attention.
Research and development of high-efficiency, low-toxicity, multifunctional gas-phase corrosion inhibitors are the development direction of gas phase corrosion inhibition. The green corrosion inhibitor can be obtained by extracting and separating the corrosion inhibitor components from natural plants and animals and performing chemical modification. Phytic acid is present in oils and cereal seeds. Rice bran or wheat bran is used as raw material, soaked in dilute acid, filtered, neutralized and precipitated with lime and sodium hydroxide, then acidified and exchanged with ion exchange resin, and concentrated under reduced pressure. A light yellow syrupy liquid obtained by decolorization and filtration. Phytic acid is extremely low in toxicity and is a rare metal chelating agent. The use of passivating agents as plating additives, metal corrosion inhibitors in water-soluble media, additives for corrosion protection coatings, galvanizing and tin plating materials has been reported. However, studies on phytic acid as a vapor phase corrosion inhibitor have not been reported yet. The gas phase corrosion inhibition performance of phytic acid was studied using dicyclohexylamine nitrite as a reference.
First, phytic acid as a gas phase corrosion inhibitor Various performance experiments 1. Gas phase rapid screening test said that 1g of phytic acid 4 were dissolved in 10ml of water, 3 of which were adjusted with ammonia to pH 7, 9, 11 and the other 1 Keep its pH value at 1.15, and coat them separately on a 150mm x 360mm neutral paper, and air dry naturally.
2. Corrosion loss test According to the coating amount of 10, 15, 20, 25, 30, 35, 40 g/m2, anti-rust paper for testing was prepared and tested according to the method and procedure specified in Appendix B of qB1319-91. After the end of the test, the corrosion product on the sample surface was cleaned, washed with acetone, weighed after drying, and the relationship between the coating amount and the corrosion rate was plotted, and the corrosion rate was calculated.
3. Confined space volatilization reduction test Weigh 1 g of phytic acid and dicyclohexylamine nitrite and dissolve them completely in 20 ml of water. Two sheets of 200mm x 200mm neutral paper are taken, dried in an oven at 50°C for 15 minutes, cooled in a desiccator, and weighed. 20ml of phytic acid solution and nitrite diamine solution are applied. On dry paper, after drying, drying in an oven at 50°C for 15 minutes, cooling in a desiccator, weighing its quality, and then placing them in an oven for continuous drying 72H, cooling in a desiccator, then weighing Its quality, calculate the weightlessness rate.
4. Test of gas phase corrosion inhibition performance A3 steel was used to make 25mm×50mm×3mm gas phase fast screening samples and 50mm×50mm×3mm hot and humid samples, polished with sandpaper, washed with acetone, and weighed after drying for 12H. . Using tin plate and galvanized steel plate made of 25mm × 50mm gas phase fast screening samples and 50mm × 50mm damp heat samples, dipping with acetone, dried 12H and weighed for later use. The dinitrohexylamine nitrite rust preventive paper for testing was prepared at a coating weight of 20 g/m2, and the specification was 150 mm x 120 mm. Vapour phase rapid screening test: roll 150mm x 120mm VCI paper into a cylinder, and put it in a cleaned and dried test tube to attach a wall tube, cover it with a rubber stopper, and place it in an oven at 50±2°C for 2H. After removal, the test piece was quickly hung and placed in an oven at 50±2° C. for a constant temperature of 2H. At the same time, a blank control experiment was performed.

Remove the test tube and inject 15 ml of distilled water, and place it in an oven at 50±2°C to start the test. Work 8 hours a day, and then stop running 16H, 24H is a cycle. After 7 cycles, the test was completed. Damp heat test: The test piece is wrapped in anti-rust paper, hung in the hot and humid box, at a temperature of 49±1°C and a relative humidity of more than 95%, working 8 hours per day and then stopping for 16H, 24H is a cycle. The test ended after 7 weeks.
Second, the experimental results 1. Gas phase rapid screening test By adding ammonia in phytic acid solution after different pH value of gas phase rapid screening test to determine the optimal pH value of phytic acid as a vapor phase inhibitor. After 1 g of phytic acid is dissolved in 10 ml of water, the pH value is 1.15, and the acidity is strong. When ammonia is added, the color of the solution changes from light yellow to dark brown, accompanied by an exothermic phenomenon. This indicates that a chemical reaction occurred and a phytate ammonia salt was generated. Phytic acid was used as a vapor phase rust-inhibiting paper corrosion inhibitor. In the natural state, pitting occurred within 24H. When the pH was adjusted to 7 with ammonia water, pitting occurred within 96 hours. When the pH value is 9, there is a good gas phase corrosion inhibition performance during the test period. Therefore, when phytic acid is used as a vapor phase corrosion inhibitor, the pH value of ammonia is adjusted to about 9 to exert its good gas phase corrosion inhibition performance. This shows that the vaporized phytinic acid after ammoniating has a high corrosion resistance.
2. Corrosion weight loss test The purpose of the corrosion weight loss test is to study the relationship between the coating weight and the weight loss rate. According to the test result (gas phase fast screening test), the pH of the phytic acid solution was adjusted to approximately 9 with ammonia and the corrosion weight loss test was performed. It is concluded that phytic acid is a dangerous type of vapor phase rust-proof wrapper corrosion inhibitor. When the coating amount is less than 15g/m2 or more than 30g/m2, a little corrosion will occur within 24H, and the vapor phase corrosion inhibition effect is relatively poor. The rate is larger. Therefore, when phytic acid is used as a vapor phase anti-rust paper inhibitor, the coating amount should be controlled within the range of 15 to 30 g/m2.
3. Confined space volatilization reduction test Confined space volatilization reduction test results are shown in Table 1 (see the magazine for details). In the volatilization reduction test of confined space, the weight loss rate of phytic acid was greater than that of dicyclohexyl nitrate. This indicates that the phytic acid is saturated in the confined space and the pressure of dicyclohexyl nitrate is large. Therefore, when phytic acid is used as a corrosion inhibitor for vapor phase rust-proof paper, it can quickly volatilize and fill the packaging space and adsorb onto the metal surface, thereby acting as a corrosion inhibitor.
4. Inhibition performance test The purpose of the corrosion weight loss test is to study the relationship between the amount of coating and the weight loss rate. According to the test result (gas phase fast screening test), the pH of the phytic acid solution was adjusted to approximately 9 with ammonia and the corrosion weight loss test was performed. The gas phase fast screening test results show that, when the coating amount is 20 g/m2, the gas phase corrosion resistance of phytic acid to A3 steel is higher than that of dicyclohexyl nitrate. At the same time, phytic acid also has good gas phase corrosion inhibition performance on tin-plated materials and galvanized materials.
Damp heat test results are shown in Table 2. From this test result, it can be confirmed that phytate has good moisture-heat resistance when used as a rust-proof wrapper corrosion inhibitor, and can be used in a high-temperature and high-humidity environment.
3. Conclusions 1. When phytic acid is used as a vapor phase corrosion inhibitor, the pH must be adjusted to about 9 with ammonia, so as to better perform its vapor phase inhibitor performance.
2. Vapor Inhibition Performance of Phytic Acid Dicyclohexylamine nitrate is highly corrosion-inhibiting and is an efficient vapor phase inhibitor. At the same time, phytic acid also has good gas phase corrosion inhibition performance for non-ferrous metals such as tin-plated steel plates and galvanized steel plates, and belongs to a multifunctional gas phase corrosion inhibitor.
3. In the high temperature and high humidity environment, the non-toxic phytic acid has good vapor corrosion inhibition performance for ferrous metals, tin-plated steel sheets, and galvanized steel sheets.
4. Phytic acid is an ideal alternative to nitrite corrosion inhibitors.