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CN-121992385-A - Environment-friendly low-slag low-consumption phosphating solution and preparation method thereof

CN121992385ACN 121992385 ACN121992385 ACN 121992385ACN-121992385-A

Abstract

An environment-friendly low-slag low-consumption phosphating solution and a preparation method thereof belong to the technical field of metal surface rust-proof treatment solutions. The chemical composition of the chemical composition comprises, by mass, 8-13% of zinc oxide, 8-12% of nitric acid, 17-25% of phosphoric acid, 0.5-0.8% of citric acid, 0.3-0.5% of hydroxylamine sulfate, 0.3-0.5% of sulfamic acid and the balance of water. The preparation method comprises the steps of preparing zinc oxide suspension, preparing zinc salt solution and preparing finished phosphating solution. The method has the advantages of reducing the ineffective consumption of phosphate ions from the source, avoiding a large amount of sediment caused by nitric acid of a strong oxidant while ensuring the compactness and the rust resistance of the zinc phosphating film, inhibiting spontaneous precipitation of free zinc ions and phosphate ions, and well maintaining the ion balance of the system.

Inventors

  • JI WEICAI
  • JI XINCHUN

Assignees

  • 季卫才

Dates

Publication Date
20260508
Application Date
20260226

Claims (10)

  1. 1. The environment-friendly low-slag low-consumption phosphating solution is characterized by comprising, by mass, 8-13% of zinc oxide, 8-12% of nitric acid, 17-25% of phosphoric acid, 0.5-0.8% of citric acid, 0.3-0.5% of hydroxylamine sulfate, 0.3-0.5% of sulfamic acid and the balance of water.
  2. 2. The environment-friendly low-slag low-consumption phosphating solution according to claim 1, wherein the chemical composition comprises, by mass, 13% of zinc oxide, 8% of nitric acid, 20% of phosphoric acid, 0.6% of citric acid, 0.3% of hydroxylamine sulfate, 0.4% of sulfamic acid and the balance of water.
  3. 3. The environment-friendly low-slag low-consumption phosphating solution according to claim 1, wherein the chemical composition comprises, by mass, 11% of zinc oxide, 10% of nitric acid, 17% of phosphoric acid, 0.8% of citric acid, 0.4% of hydroxylamine sulfate, 0.5% of sulfamic acid and the balance of water.
  4. 4. The environment-friendly low-slag low-consumption phosphating solution according to claim 1, wherein the chemical composition comprises, by mass, 8% of zinc oxide, 12% of nitric acid, 25% of phosphoric acid, 0.5% of citric acid, 0.5% of hydroxylamine sulfate, 0.3% of sulfamic acid and the balance of water.
  5. 5. The environment-friendly low-slag low-consumption phosphating solution according to claim 1 is characterized in that the purity of zinc oxide is more than 98-99.7%, the mass percentage concentration of nitric acid is 65-68%, citric acid is white semitransparent crystal or powder with the main content of more than 99.5%, hydroxylamine sulfate is colorless or white crystal or crystalline powder with the main content of 99% of chemical purity, and sulfamic acid is industrial sulfamic acid with the purity of more than 99.5%.
  6. 6. A method for preparing the environment-friendly low-slag low-consumption phosphating solution as claimed in claim 1, which is characterized by comprising the following steps: s1, preparing zinc oxide suspension, namely adding 8-13% of zinc oxide in percentage by mass into a stirring container which contains water and is provided with a stirrer for stirring, and controlling the stirring temperature, the stirring time and the stirring speed to obtain the zinc oxide suspension; s2, preparing zinc salt solution, sequentially adding 8-12% of nitric acid and 17-25% of phosphoric acid according to the mass percentage ratio into the stirring container in the step S1, and continuing stirring until zinc oxide is completely dissolved, wherein the temperature of continuing stirring is medium temperature, and the time and the speed of continuing stirring are controlled to obtain zinc salt solution; S3, preparing a finished phosphating solution, sequentially adding 0.5-0.8% of citric acid, 0.3-0.5% of hydroxylamine sulfate and 0.3-0.5% of sulfamic acid according to the mass percentage ratio into the zinc salt solution in the step S2, stirring, and controlling the stirring temperature, the stirring time and the stirring rotating speed to obtain the environment-friendly low-slag low-consumption phosphating solution.
  7. 7. The method for preparing the environment-friendly low-slag low-consumption phosphating solution as claimed in claim 6, wherein the water in the step S1 is deionized water or reverse osmosis water, and the stirring temperature, the stirring time and the stirring speed are controlled to be normal temperature, the stirring time is controlled to be 20-30min and the stirring speed is controlled to be 80-100rpm.
  8. 8. The method for preparing an environmentally friendly low-slag low-consumption phosphating solution as claimed in claim 6, wherein the medium temperature in the step S2 is 60-80 ℃, the time and the rotating speed for continuously stirring are controlled to be 20-40min, and the speed for continuously stirring is controlled to be 85-110rpm.
  9. 9. The method for preparing an environmentally friendly low-slag low-consumption phosphating solution according to claim 6, wherein the temperature, time and speed of stirring are controlled to be normal temperature, 30-60min and 80-100rpm respectively.
  10. 10. The method for preparing an environmentally friendly low-slag low-consumption phosphating solution according to claim 6, wherein the pH value of the environmentally friendly low-slag low-consumption phosphating solution in the step S3 is less than 1.

Description

Environment-friendly low-slag low-consumption phosphating solution and preparation method thereof Technical Field The invention belongs to the technical field of metal surface rust-proof treatment liquid, and particularly relates to an environment-friendly low-slag low-consumption phosphating solution and a preparation method thereof. Background Among the metal surface treatment processes, the phosphating process is widely used in links such as metal coating pretreatment, wire drawing pretreatment, cold drawing of steel pipes, finish rolling, and rust prevention of finished steel pipes, and the phosphating treatment is performed before the coating in order to improve the adhesion of a coating film and the corrosion resistance of a base material. Depending on the environment of use, the phosphating solutions are classified into normal temperature type (30-45 ℃), low temperature type (such as CN100443632A, the disclosure of "a low temperature zinc phosphating solution" < 30-38 ℃), medium temperature type (50-70 ℃) and high temperature type (80-90 ℃). The energy consumption of normal-temperature and low-temperature phosphating is low, but the phosphating time is long, the efficiency is low, and the industrial scale-up production requirement is difficult to meet. To promote the phosphating reaction, it is generally necessary to add sodium nitrite in a high concentration as an accelerator, but this causes a problem of large amounts of sediment and the like. The high-temperature phosphating time is shorter, which is favorable for meeting the requirement of industrial production, but has high energy consumption, and the problem of more sediment is also existed, which is not suitable for the energy-saving, saving and environment-friendly economic spirit advocated by the whole society at present. The mechanism of action of the sodium nitrite as an accelerator in the normal-temperature and medium-temperature zinc phosphating solutions is that ferrous ions (Fe 2+) generated during phosphating are oxidized into ferric ions (Fe 3+) by sodium nitrite, so that a large amount of water-insoluble ferric phosphate (FePO 4) sediments are formed in the phosphating solution, and the tank solution is white liquid (which is called white phosphating in the industry). In particular, sodium nitrite has been limited by the european union REACH (chemical registration, assessment, licensing and restriction) regulations, and the "hazardous chemicals catalogue" in our country also lists it as an acute poison and a carcinogen, with high operational risk, stringent regulatory requirements, and increased solid waste disposal costs due to its environmental impact. The low-slag-free phosphating solution, in particular, the slag-free phosphating solution is quite well influenced by industry, such as CN115725964A recommends a low-temperature low-slag phosphating solution and a preparation method thereof, and the patent needs to additionally add sodium dodecyl sulfate as a corrosion inhibitor, so that the composition is high, the system is complex and comprises expensive special chemicals, and nickel acetate, organic peroxide such as benzoyl peroxide and the like, diethylene glycol and the like are used, so that the raw material cost is high and the sediment is still more. In addition, as CN103695881A provides a normal temperature slag-free rapid phosphating solution and a preparation method thereof, sodium metanitrobenzenesulfonate serving as an accelerator in the formula belongs to nitrobenzene derivatives, is toxic and difficult to degrade, EDTA sewage serving as a chromium mixture in the formula is difficult to treat, heavy metal re-dissolution pollution of water is caused, zinc nitrate in the formula accounts for 20-25%, so that a large amount of zinc ions are introduced, environmental load is increased, sodium metanitrobenzenesulfonate in the formula serves as an oxidizing accelerator to oxidize Fe 2+ into Fe 3+, so that a large amount of ferric phosphate sediment is generated, EDTA can strongly complex and inhibit the sediment, but once supersaturation and/or pH change are carried out, the sediment problem can be recurred, the price of the zinc nitrate is far higher than that of zinc oxide and nitric acid alone, and excessive complexing of the EDTA affects nucleation, so that a film layer (phosphating film layer) is too thin or coarse in crystallization. With the remarkable enhancement of environmental protection consciousness, saving type and energy saving type economic consciousness of the whole society, the method has become a technical problem for developing and using phosphating solution manufacturers to pay attention to and expect to be effectively solved in the early days, such as how to effectively eliminate residual zinc oxide, reduce or inhibit sediment, assist in reducing consumption, facilitate production control and the like. CN100443632A (a low-temperature zinc-based phosphating solution) is environment-friendly due to the us