CN115044895B - Corrosion-resistant phosphating solution using enalapril maleate and preparation method and application thereof - Google Patents

Abstract

The invention discloses a corrosion-resistant phosphating solution using enalapril maleate, a preparation method and application thereof. In terms of mass fraction, the raw material formula of the corrosion-resistant phosphating solution using enalapril maleate consists of 0.1-1 part of organic phosphonic acid, 5-15 parts of zinc salt, 5-10 parts of nitrate, 0.1-0.2 part of horse Enalapril toate, 0.3-0.8 parts of surfactant, 80-100 parts of water; adjust the pH to 1-3. The present invention adds enalapril maleate, a drug for clinical treatment of hypertension, as an accelerator, and the active ingredients in it can be adsorbed on the metal surface to preferentially form phosphating nucleation sites. On the one hand, it can promote the phosphating film at a lower temperature. Rapid conversion, on the other hand, can enhance the corrosion resistance of the phosphating film. The accelerator is harmless to the human body and is green and environmentally friendly. Unlike traditional phosphating accelerators, no toxic and harmful substances will be produced during use; uniform and fine phosphating films with excellent corrosion resistance can be obtained by applying the phosphating solution of the invention.

Description

Corrosion-resistant phosphating solution utilizing enalapril maleate and its preparation method and application

technical field

The invention relates to a phosphating solution, in particular to a corrosion-resistant phosphating solution using enalapril maleate, a preparation method and application thereof, and belongs to the technical field of metal material surface treatment.

Background technique

Corrosion of metals causes serious damage to the global economy and the environment in industries as diverse as automotive, marine and pipeline. Phosphating is one of the surface treatment methods widely used to prevent metal corrosion. Phosphating includes chemical phosphating and electrolytic phosphating, that is, a chemical or electrochemical reaction occurs during the contact between the metal and the phosphating solution, and finally an inorganic film is deposited on the metal surface. The phosphating film has excellent hardness and insulation. As a surface coating, it can provide certain corrosion protection and lubrication for the metal substrate; as an intermediate coating, the presence of the phosphating film can improve the organic coating between the metal and the subsequent coating. the adhesion between them.

The traditional phosphating process often uses medium and high temperature phosphating, which consumes more energy. If the phosphating temperature is lowered, the effect of the phosphating film will be poor. It is necessary to prolong the phosphating time to ensure the phosphating quality, and the prolongation of the phosphating time will reduce the As a result, the traditional phosphating process often cannot balance energy saving and high efficiency under the premise of ensuring the effect of phosphating film. However, both increasing the phosphating temperature and prolonging the phosphating time are unfavorable for industrial applications.

The traditional phosphating accelerators are nitrite, chromate, fluoride, etc., which are easy to produce harmful substances during the phosphating process, which is not environmentally friendly. At the same time, the accelerator oxidizes Fe ²⁺ to Fe ³⁺ , resulting in the formation of A large amount of sediment increases the cost of three wastes treatment. The use of some new accelerators such as nanoparticles reduces the stability of the phosphating solution. The nanoparticles in the phosphating solution have a large surface energy and are easy to aggregate and settle, which is not conducive to continuous industrial operation. Therefore, it is very important to choose a new green accelerator to fundamentally avoid the use of harmful accelerators and to prepare energy-saving and efficient phosphating films with excellent corrosion resistance.

Chinese invention patent CN201710206943.3 discloses a green method for rapidly preparing phosphating film at low temperature. In terms of parts by mass, the method comprises 5-8 parts of dihydrogen phosphate, 6-9 parts of nitrate, 0.5-3 parts of phosphoric acid, 0.05-0.5 parts of graphene oxide, 0.1-1 part of stabilizer, and 6 parts of pH buffering agent. ～10 parts and 100～120 parts of water are put into the reaction kettle, the temperature is raised to 20～40℃, and the kettle is discharged after stirring for 20～60 minutes; The temperature of the chemical treatment is raised to 15-40°C, and the steel specimen is immersed in it, treated, and dried to obtain a phosphating film. This technology has low phosphating temperature, short phosphating time, and less sediment, but the accelerator used is graphene oxide nanoparticles, which are easy to aggregate and settle, resulting in poor stability of the phosphating solution. Dispersion treatment is required before the first use, which is not conducive to continuous use in industry.

Chinese invention patent application CN201610008581.2 discloses a method for preparing a phosphating film on the surface of low alloy steel. This method reduces the phosphating time by performing sandblasting activation pretreatment on the surface of the substrate, and has high efficiency. ℃, which belongs to medium and high temperature phosphating, which consumes more energy. At the same time, the phosphating solution contains formaldehyde and sodium fluoride, which is not environmentally friendly enough.

Chinese invention patent application CN201410120074.9 discloses a flameproof surface phosphating treatment process and the phosphating solution used. The phosphating solution can reduce the phosphating temperature to below 0 DEG C, and the prepared phosphating film has excellent corrosion resistance. However, in order to ensure the performance of the phosphating film, the phosphating time at 0°C is extended to 4 hours. The phosphating time is too long and the efficiency is too low, which is not conducive to large-scale industrial application. Moreover, nitric acid and sodium fluoride are used as accelerators in the formula, which is not environmentally friendly and increases the cost of three wastes treatment.

Chinese invention patent CN201210263671.8 discloses a low-temperature phosphating solution containing sodium hydroxymethylcellulose. The phosphating solution is stable, the phosphating operating temperature is 10-35°C, and the phosphating treatment time is 4-10 minutes, which is more energy-saving and efficient, but the phosphating solution is added with chromate which is harmful to the human body, which is not environmentally friendly. The thickness of the phosphating film per unit area is about 2g/m ² , and the quality of the phosphating film is poor.

Contents of the invention

In view of the above comparative analysis, this patent aims to solve the problems of high phosphating operation temperature, long phosphating time, and harmful phosphating accelerators, and provide a corrosion-resistant phosphating solution using enalapril maleate and its preparation method and application , Rapid phosphating under low temperature conditions, excellent corrosion resistance of phosphating film, less sediment.

The clinical medicine used in the present invention is enalapril maleate used for treating hypertension, and the active ingredient of the medicine is enalapril maleate, which has multiple oxygen atoms, nitrogen atoms, heterocyclic structures, Aromatic bonds and benzene rings, as electrophilic and nucleophilic active reaction sites, are preferentially quickly adsorbed on the surface of the substrate to form a large number of crystal nuclei. The existence of a large number of crystal nuclei can effectively refine the phosphate crystals and form finer crystals to block the corrosion medium. Intrusion to improve the corrosion resistance of the phosphating film.

The invention utilizes the property that enalapril maleate can be quickly and effectively adsorbed on metals, grinds the tablet into powder, sieves through 200-300 meshes, and puts it into the phosphating solution. The drug can be completely dissolved in the phosphating solution and remains stable for a long time without adding a large amount of stabilizer and long-term ultrasonic dispersion treatment.

The method of the invention explores the secondary utilization of clinical drugs in industry, provides ideas for the treatment of waste drugs, saves drug treatment costs and effectively improves the performance of the phosphating film, and the amount of sediment in the phosphating process is small. Compared with traditional phosphite accelerators, enalapril maleate as an accelerator is more environmentally friendly and saves the cost of waste treatment; compared with nanoparticle accelerators, the phosphating solution added with enalapril maleate is very Stable, avoiding the redispersion of nanoparticles before secondary use, which is conducive to continuous industrial production; enalapril maleate as a phosphating accelerator can reduce the phosphating operating temperature while ensuring the excellent corrosion resistance of the phosphating film , saving phosphating operation time, energy saving and higher efficiency.

The object of the invention is achieved through the following technical solutions:

The anti-corrosion phosphating solution using enalapril maleate, in terms of mass fraction, the composition of raw materials is 0.1-1 parts of organic phosphonic acid, 5-15 parts of zinc salt, 5-10 parts of nitrate, 0.1-0.2 parts Enalapril maleate, 0.3-0.8 parts of surfactant, 80-100 parts of water; adjust pH to 1-3.

In order to further realize the purpose of the present invention, preferably, the organic phosphonic acid is one of hydroxyethylidene diphosphonic acid, aminotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid one or more species.

Preferably, the zinc salt is one or more of zinc dihydrogen phosphate and its hydrate, zinc oxide, zinc nitrate and its hydrate.

Preferably, the nitrate is one or more of zinc nitrate, calcium nitrate, nickel nitrate and copper nitrate.

Preferably, the surfactant is one or more of alkylphenol and ethylene oxide condensate, alkylphenol polyoxyethylene ether.

Preferably, the pH adjustment is by adding ammonia water, sodium hydroxide or potassium hydroxide.

The preparation method of the corrosion-resistant phosphating solution using enalapril maleate: in terms of mass fraction, 0.1 to 1 parts of organic phosphonic acid, 5 to 15 parts of zinc salt, 5 to 10 parts of nitrate, 0.1 ~0.2 part of enalapril maleate, 0.3~0.8 part of surfactant, and 80~100 parts of water are mixed and stirred for 1~3 hours until the materials are dissolved, and the pH is adjusted at 1~3 to obtain a corrosion-resistant phosphating solution.

The application of the corrosion-resistant phosphating solution using enalapril maleate in the preparation of corrosion-resistant phosphating film: immerse the metal base material that has been polished and derusted, alkali-washed, and pickled In the phosphating solution, keep it for 8-15 minutes, take it out, rinse and dry it in the air, and obtain a corrosion-resistant phosphating film.

Preferably, the rust removal is to put the metal substrate into a container filled with fine sand, shake and shake for 15-25 minutes, then rinse and dry to remove surface rust;

The alkali washing is to put the rust-removed metal base material into the alkali washing solution, shake and wash at 45-55°C for 5-12 minutes, then rinse and dry;

The pickling is to put the alkali-washed metal base material into the pickling liquid and wash it at room temperature for 25-35 minutes, then rinse and dry it.

Preferably, the alkaline washing solution includes 10-20wt% NaOH and 2-8wt% Na ₂ CO ₃ , and the rest is water; the acid washing solution includes 8-12wt% HCl and 5-13wt% H ₂ SO ₄ , the rest is water; the metal substrate is one or more of Q235 steel, Q275 steel, 45# steel, and 65Mn steel.

The present invention mainly utilizes enalapril maleate as an accelerator. When the metal substrate is immersed in a phosphating bath, the active ingredient enalapril maleate in the formula relies on multiple oxygen atoms, nitrogen atoms, heterocyclic structures, Electrophilic and nucleophilic active reaction sites such as aromatic bonds and benzene rings are preferentially adsorbed on the metal substrate, quickly forming a large number of crystal nuclei, and controlling the size of phosphate crystals in disguise. At the same time, the metal substrate will dissolve ferrous ions in the acidic phosphating solution, and the ferrous ions will react with the free nitrate, zinc ions, and phosphate in the phosphating solution, and continue to grow on the formed nuclei. Gradually cover the entire substrate surface. Yet because this phosphating solution is acidic, the free acidity of phosphating solution is between 10～15, and total acidity is between 100～120, and acid ratio is between 6～12, and the present invention needs to control the maleic acid in formula. The dosage of napril is 0.1-0.2 parts. If enalapril maleate is excessive, the free acidity of the phosphating solution will increase, making the phosphating process violent, and a large amount of gas will be generated on the surface of the substrate to hinder the formation of phosphate crystals. growth, damage the quality of phosphate film.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. Enalapril maleate is originally a clinical drug for the treatment of hypertension, but the drug has a strict shelf life, and the expired drug also needs strict processing procedures. The present invention finds that using enalapril maleate As a phosphating accelerator, it can simply soak the metal substrate at 35-45°C for 8-15 minutes to obtain a phosphating film with excellent performance. For example, the corrosion rate of the phosphating film tested by the present invention changes from 1.099mpy before modification to 0.0246mpy, and the corrosion rate is reduced by two orders of magnitude, realizing low temperature and rapid phosphating, and taking into account environmental protection and high quality of the phosphating film production while saving energy.

2. The green accelerator enalapril maleate used in the present invention is clinically used to treat high blood pressure. It is harmless to the human body, and its ground powder can be completely dissolved in the phosphating solution to form a long-term stable The phosphating solution avoids the aggregation and deposition of nano-accelerators and requires re-dispersion before secondary use, which is conducive to continuous industrial work;

3, the promoting process of enalapril maleate of the present invention is mainly carried out by physical adsorption, there is no harmful gas produced in the traditional nitrite promoting process and the amount of sediment is small, reducing the cost of three wastes treatment; and the maleic acid of the present invention relies on Napril can preferentially react with the metal through the electrophilic and nucleophilic active sites, forming a large number of crystal nuclei on the metal surface, and the final phosphating film is more uniform under the scanning electron microscope than the phosphating film formed without adding the drug Fine, covering the base material more completely.

Description of drawings

Fig. 1 is a scanning electron microscope picture of the phosphating film prepared on the Q235 substrate before and after adding the clinical drug enalapril maleate as an accelerator in Example 3 at the same scale, and the magnification is 100 times.

Fig. 2 is a scanning electron microscope picture of the phosphating film prepared on the Q235 substrate before and after adding the clinical drug enalapril maleate as an accelerator in Example 3 at the same scale, with a magnification of 500 times.

Fig. 3 is a 3D profile diagram of the phosphating film prepared on the Q235 substrate before and after adding the clinical drug enalapril maleate as an accelerator in Example 3.

Figure 4 is a comparison of the roughness of the phosphating film prepared on the Q235 substrate before and after adding the clinical drug enalapril maleate as an accelerator in Example 3.

Fig. 5 is the polarization curve of the phosphating film prepared on the Q235 substrate soaked in 3.5wt% NaCl solution before and after adding the clinical drug enalapril maleate as an accelerator in Example 3.

Detailed ways

In order to better understand the present invention, the present invention will be further described below in conjunction with the accompanying drawings and examples, but the examples are not intended to limit the protection scope of the present invention.

In the embodiment of the present invention, a scanning electron microscope (SEM, SU-8200, Japan) was used to characterize the morphology change of the phosphating film before and after adding the clinical drug enalapril maleate as an accelerator.

In the embodiment of the present invention, a 3D profiler (Rtec, American) is used to measure the roughness of the phosphating film before and after adding the clinical drug enalapril maleate as an accelerator. The specific test method is to select five areas of the sample by moving the lens left and right, and move the lens up and down to reach the surface of the substrate and the highest point of the crystal to measure the thickness and uniformity of the film layer, and then calculate the roughness of the phosphating film.

The embodiment of the present invention uses the polarization curve obtained by CHI-660E electrochemical workstation to characterize the corrosion resistance of the phosphating film formed before and after adding the clinical drug enalapril maleate as an accelerator and soaked in 3.5wt% NaCl solution.

Example 1

First, the metal substrate 45# steel is polished, rusted, alkali washed, and pickled. The rust removal process is to put the metal base material into a container filled with fine sand, shake and shake for 20 minutes, then rinse and dry to remove surface rust; alkali cleaning is to put the rust-removed metal base material into an alkaline washing solution at 50°C After shaking and washing for 10 minutes, rinse and dry; the alkaline washing solution includes 15wt% NaOH and 5wt% Na ₂ CO ₃ , and the rest is water. Pickling is to put the metal base material after alkaline cleaning into the pickling solution for washing at room temperature for 30 minutes, then rinse and dry; the pickling solution includes 10wt% HCl and 10wt% H ₂ SO ₄ , and the rest is water.

In terms of parts by mass, the raw materials of the corrosion-resistant phosphating solution using enalapril maleate consist of: 5 parts of zinc dihydrogen phosphate dihydrate, 5 parts of zinc nitrate, 1 part of ethylenediamine tetramethylene phosphonic acid, Enalapril maleate 0.1 part, TX-9 0.3 part, water 80 parts. The pH was adjusted to 2.4 with ammonia water, and the measured free acidity was 10.5, the total acidity was 110, and the acid ratio was 10.48. Mix the above materials evenly. The 45# steel that has been activated by rust removal, alkali washing and pickling is immersed in a phosphating pool at 40°C for 10 minutes, rinsed with water and dried to obtain a phosphating specimen.

The phosphating film layer obtained in Example 1 is gray-black, with a smooth and fine surface, no substrate exposed when magnified 100 times, surface roughness of 4.35 μm, film thickness of 1.98 g/m ² , good corrosion resistance, phosphorus No corrosion occurs in the neutral salt spray test of the chemical film for 13 hours, and the annual corrosion rate calculated by the polarization curve is 0.1221mpy.

Example 2

First, the metal substrate Q275 steel is polished, rust-removed, alkali-washed, and pickled. The derusting process is to put the metal base material into a container filled with fine sand, shake and shake for 15 minutes, rinse and dry to remove the surface rust; alkaline cleaning is to put the derusted metal base material into the alkaline washing solution at 55°C After shaking and washing for 5 minutes, rinse and dry; the alkaline washing solution includes 10wt% NaOH and 8wt% Na ₂ CO ₃ , and the rest is water. Pickling is to put the metal base material after alkali washing into the pickling liquid for washing at room temperature for 35 minutes and then rinse and dry; the pickling liquid includes 12wt% HCl and 5wt% H ₂ SO ₄ , and the rest is water.

In terms of parts by mass, the raw materials of the anti-corrosion phosphating solution using enalapril maleate consist of: 8 parts of zinc oxide, 7 parts of calcium nitrate, 0.8 parts of aminotrimethylene phosphonic acid, 0.13 parts of enalapril maleate parts, O-300.5 parts, water 88 parts. The pH was adjusted to 2.4 with ammonia water, and the measured free acidity was 11.2, the total acidity was 110, and the acid ratio was 9.82. After the above materials are mixed evenly, put them into the phosphating tank and raise the temperature to 40°C for standby. Alkali washing liquid is made by immersing the Q275 steel activated by derusting alkali washing and pickling into the phosphating pool for 10 minutes, then rinsing with water and drying to obtain the phosphating treated specimen.

The phosphating film layer obtained in Example 2 is gray-black, the surface is smooth and dense, no substrate is exposed when magnified 100 times, the phosphate crystal grains are fine, the surface roughness is 3.76 μm, and the film thickness is 2.33 g/m ² . The corrosion resistance is good, the phosphating film has no corrosion in the neutral salt spray test for 20 hours, and the annual corrosion rate calculated by the polarization curve is 0.0606mpy.

Example 3

First, the metal substrate Q235 steel is polished, rusted, alkali washed, and pickled. The rust removal process is to put the metal base material into a container filled with fine sand, shake and shake for 25 minutes, then rinse and dry to remove surface rust; alkaline cleaning is to put the rust-removed metal base material into an alkaline washing solution at 45 °C After shaking and washing for 12 minutes, rinse and dry; the alkaline washing solution includes 20wt% NaOH and 2wt% Na ₂ CO ₃ , and the rest is water. Pickling is to put the metal base material after alkaline cleaning into the pickling liquid for washing at room temperature for 35 minutes and then rinse and dry; the pickling liquid includes 8wt% HCl and 13wt% H ₂ SO ₄ , and the rest is water.

In terms of parts by mass, the raw materials of the corrosion-resistant phosphating solution using enalapril maleate consist of: 10 parts of zinc nitrate, 9 parts of nickel nitrate, 0.6 parts of ethylenediamine tetramethylene phosphonic acid, and enalamic acid 0.16 parts of Puli, 0.6 parts of OP-4, 95 parts of water, adjust the pH to 2.4 with ammonia water, the measured free acidity is 12, the total acidity is 110, and the acid ratio is 9.17. After the above materials are mixed evenly, put them into the phosphating tank and raise the temperature to 40°C for standby. The Q235 steel that has been activated by rust removal, alkali washing and pickling is immersed in a phosphating bath for 10 minutes, rinsed with water and dried to obtain a phosphating specimen.

Fig. 1 is the scanning electron microscope pictures under the same scale before and after adding the clinical drug enalapril maleate as an accelerator in Example 3, and the magnification is 100 times. It can be seen from the figure that the blank group without enalapril maleate (a in Figure 1) has coarse grains, sparse arrangement, and a large area of exposed substrate. However, in the control group (b in Figure 1) with enalapril maleate added, the crystal grains of the phosphating film were small, closely arranged, and closely arranged on the surface of the substrate, indicating that the addition of enalapril maleate effectively refined Phosphate crystals make the grains finer.

Fig. 2 is a scanning electron microscope picture on the same scale before and after adding the clinical drug enalapril maleate as an accelerator in Example 3, with a magnification of 500 times. From the figure, it can be seen more clearly that the blank group without adding enalapril maleate (a in Fig. 2) is compared with the control group (b in Fig. 2) adding enalapril maleate, the crystal grains are more Coarse, so adding enalapril maleate as an accelerator can promote the refinement of phosphate crystals.

Fig. 3 is a 3D contour diagram before and after adding the clinical drug enalapril maleate as an accelerator in Example 3. It can be seen more clearly from the figure that the surface of the phosphating film of the blank group without enalapril maleate (a in Fig. 3) is covered with peaks of different heights, and the distribution of the peaks is uneven. After adding enalapril maleate (b in Figure 3), the peak heights began to decrease and were at a relatively uniform level, indicating that the phosphating film was very smooth and dense, and the finer the grains, the tighter the distribution, which can effectively prevent the The erosion of corrosive media improves the corrosion resistance.

Fig. 4 is a roughness comparison before and after adding the clinical drug enalapril maleate as an accelerator in Example 3. It can be clearly seen from the figure that the surface roughness of the phosphating film surface of the blank group without adding enalapril maleate (a in Fig. 4) is much greater than that of adding enalapril maleate (b in Fig. 4 ). The data show that the roughness of the phosphating film of the blank group (a in Fig. 4) added with enalapril maleate was 9.21 μm, and the roughness of the phosphated film prepared by adding enalapril maleate (b in Fig. 4) was 9.21 μm. The degree is 2.82 μm. Therefore, the introduction of enalapril maleate inhibited the vertical growth of phosphate crystals, reduced the surface roughness of the phosphating film, and made the growth height more uniform.

Fig. 5 is the polarization curve of the phosphating film formed on the surface of Q235 soaked in 3.5wt% NaCl solution before and after adding the clinical drug enalapril maleate as an accelerator in Example 3. It can be seen from the figure that the corrosion resistance after the addition is significantly better than that before the addition. After calculation, the annual corrosion rate of the phosphating film changed from 1.099mpy before modification to 0.0246mpy, and the corrosion rate decreased by two orders of magnitude. It shows that adding enalapril maleate as an accelerator can enhance the corrosion resistance.

The phosphating film layer obtained in Example 3 is gray-black, the surface is smooth and dense, no substrate is exposed when magnified 100 times, the phosphate grains are fine, the surface roughness is 2.82 μm, and the film thickness is 4.02 g/m ² . The corrosion resistance is good, the phosphating film has no corrosion in the neutral salt spray test for 27 hours, and the annual corrosion rate calculated by the polarization curve is 0.0246mpy.

Example 4

First, the metal substrate 65Mn steel is polished to remove rust, alkali and pickling. The rust removal process is to put the metal base material into a container filled with fine sand, shake and shake for 20 minutes, then rinse and dry to remove surface rust; alkaline cleaning is to put the rust-removed metal base material into an alkaline washing solution at 50 ° C After shaking and washing for 10 minutes, rinse and dry; the alkaline washing solution includes 18wt% NaOH and 5wt% Na ₂ CO ₃ , and the rest is water. Pickling is to put the metal base material after alkaline cleaning into the pickling liquid for washing at room temperature for 30 minutes and then rinse and dry; the pickling liquid includes 11wt% HCl and 9wt% H ₂ SO ₄ , and the rest is water.

In terms of parts by mass, the raw materials of the corrosion-resistant phosphating solution using enalapril maleate consist of: 10 parts of zinc nitrate hexahydrate, 10 parts of copper nitrate, 0.1 part of diethylenetriaminepentamethylenephosphonic acid, maleic acid Enalapril acid 0.2 parts, OP-90.8 parts, water 100 parts. The pH was adjusted to 2.4 with ammonia water, and the measured free acidity was 13.3, the total acidity was 110, and the acid ratio was 8.27. After the above materials are mixed evenly, put them into the phosphating tank and raise the temperature to 40°C for standby. Immerse the activated 65Mn in the phosphating pool for 10 minutes after descaling, alkali washing and pickling, rinse with water and dry to obtain the phosphating specimen.

The phosphating film layer obtained in Example 4 is gray-black, the surface is smooth and dense, no substrate is exposed when magnified 100 times, the surface roughness is 4.21 μm, the film thickness is 2.16g/m ² , and the corrosion resistance is good. No corrosion occurs in the neutral salt spray test of the chemical film for 15 hours, and the annual corrosion rate calculated by the polarization curve is 0.0832mpy.

Comparative example 1-4

Using Example 3 of the present invention and the phosphating process involved in the patent application numbers CN201710206943.3, CN201610008581.2, CN201410120074.9 and CN201210263671.8 to carry out phosphating temperature, phosphating time, whether it is green and environmentally friendly, and the phosphating solution is stable Performance, phosphating film quality and other aspects were compared, and the comparison results are shown in Table 1.

The comparative example selected in Table 1 is the embodiment whose phosphating condition is the closest to Example 3 of the present invention and the phosphating effect is the best among the patent application numbers CN201710206943.3, CN201610008581.2, CN201410120074.9 and CN201210263671.8, such as Chinese invention patent application 201710206943.3 selects Example 3 as a comparison, Chinese invention patent application 201610008581.2 selects Example 1 as a comparison, and CN201410120074.9 and CN201210263671.8 both have only one embodiment.

Both Comparative Example 1 and Example 3 of the present invention belong to low-temperature phosphating, and the phosphating time is 10 minutes, which is energy-saving and high-efficiency. However, the phosphating accelerator used in Comparative Example 1 is graphene oxide nanoparticles, which has poor dispersion and is easy to agglomerate. The deposition of nanoparticles in the phosphating process will cause poor stability of the phosphating solution, and redispersion is required before the secondary phosphating begins. It is suitable for industrial continuous operation, and the present invention uses enalapril maleate as an accelerator, which can be dissolved in phosphating solution to make it stable. In addition, the film thickness of the phosphating film prepared in Comparative Example 1 was 3.0g/m ² , and the neutral salt spray test was 20h. The film thickness of the phosphating film prepared in Example 3 of the present invention was 4.02g/m ² , and the neutral salt spray test was 27h. , Excellent corrosion resistance.

The phosphating film prepared in Comparative Example 2 has excellent corrosion resistance, but it belongs to medium temperature phosphating, which consumes more energy than Example 3 of the present invention. And the accelerant and reductant used in Comparative Example 2 are sodium fluoride and formaldehyde respectively, compared with the accelerant used in Example 3 of the present invention, enalapril maleate, a drug for clinical hypertension, is not environmentally friendly enough.

Both Comparative Example 3 and Example 3 of the present invention belong to low-temperature phosphating, but in order to ensure the excellent corrosion resistance of the phosphating film in Comparative Example 3, the phosphating time must be extended to 120 minutes, which is far higher than the 10 minutes of Example 3 of the present invention. Minutes of phosphating time, the efficiency is too low, not suitable for industrial applications. In addition, in Comparative Example 3, nitric acid and sodium fluoride were used as accelerators, and the phosphating process produced harmful substances, which did not meet the requirements of green production.

Both Comparative Example 4 and Example 3 of the present invention belong to rapid phosphating under low temperature conditions, but the use of chromic acid as an accelerator in Comparative Example 4 will cause great harm to the human body and the environment, and does not meet the requirements of green production. And the thickness of the phosphating film prepared in Comparative Example 4 is between 1.9 and 2.2 g/m ² , which is slightly worse than that of Example 3 of the present invention.

Table 1

In summary, the present invention utilizes the clinical drug enalapril maleate as a phosphorylation accelerator for the first time, and the drug dissolves and exists stably in the phosphorylation solution, and the efficient phosphorylation process under low temperature conditions relies on heteroatoms Physical adsorption with heterocyclic rings on the metal substrate to form a large number of crystal nuclei, which is realized by regulating the size of phosphate grains in disguised form. No harmful substances are produced during the phosphating process, and the amount of sediment is small and the formed phosphating film is corrosion-resistant. Excellent performance. The addition of a small amount of this drug accelerator can realize rapid phosphating at low temperature to form a phosphating film with excellent corrosion resistance. The application of enalapril maleate in the present invention realizes environmental protection, low temperature and rapid phosphating. Under the premise of high quality, it can well meet the requirements of environmental protection, energy saving and high-efficiency production of phosphating film production, and there is a lot of application space, which also provides ideas for the reuse of clinical waste drugs.

It should be noted that the present invention is not limited by the above-mentioned embodiments. On the premise of not departing from the spirit and scope of the present invention, the present invention also has various changes and improvements, and these changes and improvements all fall into the claimed invention. Within the scope of protection; the scope of protection required by the present invention is defined by the claims.

Claims (10)

1. The corrosion-resistant phosphating solution utilizing enalapril maleate is characterized in that, in parts by mass, the raw material formula consists of 0.1 to 1 part of organic phosphonic acid, 5 to 15 parts of zinc salt, 5 to 10 parts of Nitrate, 0.1-0.2 parts of enalapril maleate, 0.3-0.8 parts of surfactant, 80-100 parts of water; adjust the pH to 1-3. 2. the corrosion-resistant phosphating solution utilizing enalapril maleate according to claim 1, is characterized in that, described organic phosphonic acid is hydroxyethylidene diphosphonic acid, aminotrimethylene phosphonic acid, ethylene diphosphonic acid One or more of amine tetramethylene phosphonic acid and diethylene triamine penta methylene phosphonic acid. 3. the corrosion-resistant phosphating solution utilizing enalapril maleate according to claim 1, is characterized in that, described zinc salt is zinc dihydrogen phosphate and hydrate thereof, zinc oxide, zinc nitrate and its One or more of hydrates. 4. the anti-corrosion phosphating solution utilizing enalapril maleate according to claim 1, is characterized in that, described nitrate is the one in zinc nitrate, calcium nitrate, nickel nitrate, copper nitrate or Various. 5. the corrosion-resistant phosphating solution utilizing enalapril maleate according to claim 1, is characterized in that, described tensio-active agent is alkylphenol and ethylene oxide condensate, alkylphenol polymer One or more of oxyethylene ethers. 6. The corrosion-resistant phosphating solution utilizing enalapril maleate according to claim 1, characterized in that, the pH adjustment is by adding ammonia, sodium hydroxide or potassium hydroxide. 7. The preparation method of the corrosion-resistant phosphating solution utilizing enalapril maleate described in any one of claims 1-6, is characterized in that: in mass fraction, 0.1～1 part of organic phosphonic acid, 5-15 parts of zinc salt, 5-10 parts of nitrate, 0.1-0.2 part of enalapril maleate, 0.3-0.8 part of surfactant, 80-100 parts of water, mix and stir for 1-3 hours until the material is dissolved, and adjust the pH In 1-3, a corrosion-resistant phosphating solution is obtained. 8. The application of the anti-corrosion phosphating solution utilizing enalapril maleate described in any one of claims 1-6 in the preparation of anti-corrosion phosphating film is characterized in that: the rust removal, alkali cleaning 1. Immerse the pickled metal substrate in the phosphating solution heated to 35-45°C, keep it for 8-15 minutes, take it out, rinse and dry it, and obtain a corrosion-resistant phosphating film. 9. the application of the anti-corrosion phosphating solution utilizing enalapril maleate according to claim 8 in the preparation of anti-corrosion phosphating film is characterized in that: described derusting is that metal substrate is dropped into and filled with Shake and shake in a container of fine sand for 15-25 minutes, then rinse and dry to remove surface rust; The alkali washing is to put the rust-removed metal base material into the alkali washing solution, shake and wash at 45-55°C for 5-12 minutes, then rinse and dry; The pickling is to put the alkali-washed metal base material into the pickling liquid and wash it at room temperature for 25-35 minutes, then rinse and dry it. 10. The application of the anti-corrosion phosphating solution utilizing enalapril maleate according to claim 9 in the preparation of anti-corrosion phosphating film, characterized in that: the alkaline washing solution includes 10-20wt% NaOH and 2-8wt% Na ₂ CO ₃ , the rest is water; the pickling solution includes 8-12wt% HCl and 5-13wt% H ₂ SO ₄ , the rest is water; the metal substrate is Q235 steel , Q275 steel, 45# steel, 65Mn steel in one or more.