阅读说明：本技术 一种防腐环保型磷化剂和该磷化剂的制备方法 (Anticorrosive environment-friendly phosphating agent and preparation method thereof ) 是由 段国发 胡国辉 刘腾 赵强 周晗 陈鹏 彭小明 蒲伟 向彬 张志强 于 2021-07-29 设计创作，主要内容包括：本发明公开了一种防腐环保型磷化剂和该磷化剂的制备方法,按每升体积计,该磷化剂各组分质量为：氧化锌140～150g、硝酸170g～190g、磷酸110g～130g、硝酸钙15g～30g、四硼酸钠1.5g～2g,稳定剂3g～4g、络合剂1g～1.7g、助剂2g～4g,其余为水。制备方法是：首先用部分水将氧化锌调成糊状,加入硝酸和磷酸于糊状物中,搅拌溶解,待温度降至45℃以下时,再依次加入硝酸钙、四硼酸钠,再依次加入所述稳定剂、络合剂、助剂,最后加入剩余的水。本发明的技术效果是：磷化剂使用过程中不再需要分析、调整,操作简便、适用；且能减少磷化沉渣,生成的磷化膜均匀、致密,其结晶为柱状,具有较高的耐蚀性。(The invention discloses an anticorrosive environment-friendly phosphating agent and a preparation method thereof, and the phosphating agent comprises the following components in parts by mass per liter: 140-150 g of zinc oxide, 170-190 g of nitric acid, 110-130 g of phosphoric acid, 15-30 g of calcium nitrate, 1.5-2 g of sodium tetraborate, 3-4 g of stabilizer, 1-1.7 g of complexing agent, 2-4 g of assistant and the balance of water. The preparation method comprises the following steps: firstly, mixing zinc oxide into paste by using part of water, adding nitric acid and phosphoric acid into the paste, stirring and dissolving, when the temperature is reduced to be below 45 ℃, sequentially adding calcium nitrate and sodium tetraborate, sequentially adding the stabilizer, the complexing agent and the auxiliary agent, and finally adding the rest water. The invention has the technical effects that: the phosphating agent does not need to be analyzed and adjusted in the using process, and is simple and convenient to operate and applicable; and the phosphorization sediment can be reduced, the generated phosphorization film is uniform and compact, the crystal of the phosphorization film is columnar, and the corrosion resistance is higher.)

1. An anticorrosive environment-friendly phosphating agent is characterized in that: the weight of each component is as follows according to the volume of each liter: 140-150 g of zinc oxide, 170-190 g of nitric acid, 110-130 g of phosphoric acid, 15-30 g of calcium nitrate, 1.5-2 g of sodium tetraborate, 3-4 g of stabilizer, 1-2 g of complexing agent, 2-4 g of assistant and the balance of water.

2. The corrosion-resistant environment-friendly phosphating agent as claimed in claim 1, which is characterized in that: the stabilizer is protocatechuic acid.

3. The corrosion-resistant environment-friendly phosphating agent as claimed in claim 1, which is characterized in that: the complexing agent is a mixture of citric acid and tartaric acid or a mixture of citrate and tartrate.

4. The corrosion-resistant environment-friendly phosphating agent as claimed in claim 1, which is characterized in that: the auxiliary agent is dimethyl urea and derivatives thereof.

5. The corrosion-resistant environment-friendly phosphating agent as claimed in claim 1, which is characterized in that the mass of each component is as follows by 1 liter: 140g of zinc oxide, 175g of nitric acid, 110g of phosphoric acid, 15g of calcium nitrate, 2g of sodium tetraborate, 4g of protocatechuic acid, 1g of citric acid, 2g of dimethyl urea and the balance of water.

6. The corrosion-resistant environment-friendly phosphating agent as claimed in claim 1, which is characterized in that the mass of each component is as follows by 1 liter: 150g of zinc oxide, 190g of nitric acid, 130g of phosphoric acid, 20g of calcium nitrate, 2g of sodium tetraborate, 4g of protocatechuic acid, 1.5g of tartaric acid, 4g of dimethyl urea and the balance of water.

7. The corrosion-resistant environment-friendly phosphating agent as claimed in claim 1, which is characterized in that the mass of each component is as follows by 1 liter: 140g of zinc oxide, 180g of nitric acid, 120 g of phosphoric acid, 30g of calcium nitrate, 2g of sodium tetraborate, 4g of protocatechuic acid, 1.2 g of a mixture of citric acid and tartaric acid, 3g of dimethyl urea and the balance of water.

8. The corrosion-resistant environment-friendly phosphating agent as claimed in claim 1, which is characterized in that the mass of each component is as follows by 1 liter: 145g of zinc oxide, 170g of nitric acid, 125g of phosphoric acid, 25g of calcium nitrate, 1.5g of sodium tetraborate, 3g of protocatechuic acid, 1.7g of a mixture of citrate and tartrate, 4g of dimethyl urea and the balance of water.

9. A method for preparing the corrosion-resistant environment-friendly phosphating agent as claimed in any one of claims 1 to 8, which is characterized by comprising the following steps: firstly, mixing zinc oxide into paste by using part of water, adding nitric acid and phosphoric acid into the paste, stirring and dissolving, when the temperature is reduced to below 45 ℃, sequentially adding calcium nitrate and sodium tetraborate, then sequentially adding the stabilizing agent, the complexing agent and the auxiliary agent, adding the next specified amount of material after adding one raw material and stirring to dissolve, and finally adding the rest water and stirring to obtain the phosphating agent.

Technical Field

The invention belongs to the technical field of surface treatment, and particularly relates to a phosphating agent pretreated before painting and a preparation method of the phosphating agent.

Background

The metal matrix needs to be subjected to conversion film treatment on the surface in the aspects of coating, rust prevention, wear resistance, lubrication and the like, so that the metal surface characteristics are changed, the process requirements are met, the phosphating film has a certain thickness and microscopic gaps, the rust prevention, wear resistance and lubrication effects can be obtained through post-treatment, and the adhesive force of a paint film on the metal surface can be effectively increased due to the increase of the specific surface area of the surface of the metal matrix, so that the corrosion resistance of the metal is improved, and the service life of a product is prolonged.

At present, the surface of a metal workpiece is mostly chemically treated by a phosphating agent, so that a phosphate conversion film with a certain thickness, namely a phosphating film, is formed on the surface of the metal workpiece. But the phosphating agent in the market needs to control the acid ratio, the total acidity and the free acidity, and the accelerator needs to be added for frequent adjustment and analysis in the using process, so that a large amount of sediments can be generated in the process, irregular groove inversion is used for cleaning precipitates, the use is unstable and inconvenient, and the labor intensity is high.

Disclosure of Invention

Aiming at the problems of the existing phosphating agent, the invention aims to provide an anticorrosive environment-friendly phosphating agent which does not need to be analyzed and adjusted in the using process, can be normally produced and used by being prepared by water according to requirements and being heated to a specified temperature, and is simple and convenient to operate and applicable; and can reduce the phosphorization sediment. The invention also provides a preparation method of the phosphating agent.

In order to solve the technical problems, the invention provides an anticorrosive environment-friendly phosphating agent which comprises the following components in parts by mass per liter: 140-150 g of zinc oxide, 170-190 g of nitric acid, 110-130 g of phosphoric acid, 15-30 g of calcium nitrate, 1.5-2 g of sodium tetraborate, 3-4 g of stabilizer, 1-2 g of complexing agent, 2-4 g of assistant and the balance of water.

The stabilizer is protocatechuic acid. The stabilizer can stabilize acidity, and is favorable for stably controlling the acid ratio of the phosphating agent.

The complexing agent is a mixture of citric acid and tartaric acid or a mixture of citrate and tartrate. The complexing agent has the advantages of refining phosphorized crystal grains, improving the corrosion resistance of a phosphorized film and greatly reducing the generation of sediments.

The auxiliary agent is dimethyl urea or a derivative thereof. The assistant is adsorbed on the metal surface to diffuse the phosphorized crystal nucleus to four sides, which is favorable for forming columnar crystal.

The preparation method of the phosphating agent comprises the steps of firstly mixing zinc oxide into paste by using part of water, adding nitric acid and phosphoric acid into the paste, stirring and dissolving, then sequentially adding calcium nitrate and sodium tetraborate when the temperature is reduced to be below 45 ℃, then sequentially adding the stabilizing agent, the complexing agent and the auxiliary agent, adding a specified amount of material after adding one raw material and stirring to dissolve, and finally adding the rest water and stirring to obtain the phosphating agent.

The invention has the technical effects that:

because the phosphating agent has the stabilizer, the acid ratio and the acidity do not need to be analyzed and controlled in the using process when the phosphating agent is used in the phosphating part of a workpiece, so that the phosphating sediments are greatly reduced, and the adverse effect of the phosphating sediments on the environment is reduced; heavy metals such as nickel, copper and the like are not used, so that the method is safe and environment-friendly; and because the phosphating agent of the invention has the auxiliary agent, the generated phosphating film is uniform and compact, and the crystal of the phosphating film is columnar and has higher corrosion resistance.

Drawings

The drawings of the invention are illustrated as follows:

FIG. 1 is a graph comparing the effect of low temperature phosphatizing agents on the surface of a workpiece in accordance with an embodiment of the present invention;

(A) example 1 phosphorus effect diagram;

(B) example 2 phosphorus effect diagram;

(C) example 3 phosphorus effect diagram;

(D) example 4 phosphorus effect diagram;

(E) and the phosphorization effect diagram of the existing low-temperature phosphorization agent.

Detailed Description

The invention is further illustrated by the following examples and figures:

example 1

The weight of each component is as follows according to 1 liter volume: 140g of zinc oxide, 175g of nitric acid, 110g of phosphoric acid, 15g of calcium nitrate, 2g of sodium tetraborate, 4g of a stabilizer (protocatechuic acid), 1g of a complexing agent (citric acid), 2g of an auxiliary agent (dimethyl urea), and the balance of water.

Firstly, mixing zinc oxide into paste by using part of water, adding nitric acid and phosphoric acid into the paste, stirring and dissolving, when the temperature is reduced to below 45 ℃, sequentially adding calcium nitrate and sodium tetraborate, then sequentially adding the stabilizing agent, the complexing agent and the auxiliary agent, adding a next specified amount of material after adding one raw material and stirring to dissolve, finally adding the rest water, continuously stirring for 1h, and filtering to obtain the phosphating agent.

Example 2

The weight of each component is as follows according to 1 liter volume: 150g of zinc oxide, 190g of nitric acid, 130g of phosphoric acid, 20g of calcium nitrate, 2g of sodium tetraborate, 4g of stabilizer (protocatechuic acid), 1.5g of complexing agent (tartaric acid), 4g of auxiliary agent (dimethyl urea) and the balance of water.

Firstly, mixing zinc oxide into paste by using part of water, adding nitric acid and phosphoric acid into the paste, stirring and dissolving, when the temperature is reduced to below 45 ℃, sequentially adding calcium nitrate and sodium tetraborate, then sequentially adding the stabilizing agent, the complexing agent and the auxiliary agent, adding a next specified amount of material after adding one raw material and stirring to dissolve, finally adding the rest water, continuously stirring for 1h, and filtering to obtain the phosphating agent.

Example 3

The weight of each component is as follows according to 1 liter volume: 140g of zinc oxide, 180g of nitric acid, 120 g of phosphoric acid, 30g of calcium nitrate, 2g of sodium tetraborate, 4g of a stabilizer (protocatechuic acid), 1.2 g of a complexing agent (a mixture of citric acid and tartaric acid), 3g of an auxiliary agent (dimethyl urea) and the balance of water.

Firstly, mixing zinc oxide into paste by using part of water, adding nitric acid and phosphoric acid into the paste, stirring and dissolving, when the temperature is reduced to below 45 ℃, sequentially adding calcium nitrate and sodium tetraborate, then sequentially adding the stabilizing agent, the complexing agent and the auxiliary agent, adding a next specified amount of material after adding one raw material and stirring to dissolve, finally adding the rest water, continuously stirring for 1h, and filtering to obtain the phosphating agent.

Example 4

The weight of each component is as follows according to 1 liter volume: 145g of zinc oxide, 170g of nitric acid, 125g of phosphoric acid, 25g of calcium nitrate, 1.5g of sodium tetraborate, 3g of a stabilizer (protocatechuic acid), 1.7g of a complexing agent (a mixture of citrate and tartrate), 4g of an auxiliary agent (dimethyl urea) and the balance of water.

Firstly, mixing zinc oxide into paste by using part of water, adding nitric acid and phosphoric acid into the paste, stirring and dissolving, when the temperature is reduced to below 45 ℃, sequentially adding calcium nitrate and sodium tetraborate, then sequentially adding the stabilizing agent, the complexing agent and the auxiliary agent, adding a next specified amount of material after adding one raw material and stirring to dissolve, finally adding the rest water, continuously stirring for 1h, and filtering to obtain the phosphating agent.

Comparative testing of Performance test

1. Appearance of phosphating film

The phosphating agents of examples 1 to 4 and commercial low-temperature phosphating agents were diluted 5 times with water as they were, the surfaces of metal workpieces were treated according to the standard GB/T6807-2001, the quality of the phosphating films was examined, and the color, uniformity, crystal morphology, corrosion resistance and the like of the phosphating films were tested.

The phosphorization process parameters are as follows: the phosphating workpiece is made of Q235, the phosphating temperature is 35-45 ℃, and the phosphating time is 10-15 min. The phosphating effect of the workpiece surface is shown in figure 1.

As seen from fig. 1: after the stabilizer and the assistant are used, the phosphating film on the workpiece is uniform and compact and is columnar crystal, so that the adhesion of a paint film is facilitated, and the corrosion resistance of the paint film is greatly improved.

2. Stability of phosphating agent

The phosphating agents of examples 1 to 4 and commercially available low-temperature phosphating agents were placed in closed containers, and after 24 hours at 40 ℃, the solutions were observed for changes in appearance, delamination, clarity and transparency.

3. Corrosion resistance

The phosphating agents of examples 1 to 4 and commercially available low-temperature phosphating agents were diluted 5 times with water as they were, respectively subjected to phosphating treatment, and subjected to sealing treatment with the same type of sealing agent. The brine solution with the concentration of 3.5 percent is at the temperature of 20-25 ℃.

Remarking: and testing a saline-resistant phosphating sample, and sealing by using an LD-2711 aqueous sealant after phosphating.

The results of the performance comparison test are shown in table 1:

TABLE 1 test results

Technical project	Appearance of phosphating film	Stability of phosphating agent	Salt water resistance
				Example 1	Middle gray, uniform and dense, columnar crystal	Clear, transparent, without delamination and turbidity	No rust spot for 3h and slight rust for 4h
Example 2	Middle gray, uniform and dense, columnar crystal	Clear, transparent, without delamination and turbidity	No rust spot for 4h and slight rust for 5h
				Example 3	Middle gray, uniform and dense, columnar crystal	Clear, transparent, without delamination and turbidity	5h no rust spot
Example 4	Middle gray, uniform and dense, columnar crystal	Clear, transparent, without delamination and turbidity	No rust spot for 4h and slight rust for 5h
				Commercial phosphating agent	Light gray, uniform and dense, flaky crystal	Turbidity, no demixing and little precipitation	Slight rust in 2h

As seen from table 1: the phosphating agent prepared by the invention can greatly reduce the precipitation of phosphating slag in the use process, does not contain heavy metal ions such as nickel, copper and the like, and reduces the pollution to the environment. The components of the phosphating agent prepared by the invention are single components, can be used after being diluted by water, does not need to analyze and adjust the acid ratio and the acidity, does not generate the phenomena of layering, turbidity and the like after being stored for a long time, and ensures the effectiveness and the quality stability of the phosphating agent.

The phosphating agent is used for pretreatment before cathodic electrophoretic painting of workpieces, has stable and reliable quality, does not need to adjust acid ratio, total acidity and free acidity in the production and application process, only needs to be added according to a specified proportion and heated to meet the process requirement, directly performs phosphating according to specified time to obtain a high-quality pretreated phosphating film, and the phosphating film is naturally stored indoors for 3 months without rusting; the phosphatized product is directly subjected to cathodic electrophoretic painting, and the paint film adhesion is 0 grade.