Phosphorus-free pre-film agent and method of pre-filming

Abstract

This invention relates to the field of pre-filming and discloses a phosphorus-free pre-filming agent and a pre-filming method. The pre-filming agent comprises the reaction product of a compound shown in Formula I and a compound shown in Formula II, hydrolyzed polymaleic anhydride, and at least one azole compound. The pre-filming agent provided by this invention forms a distinct blue-purple film on the surface of the object to be pre-filmed, and the color development time of copper sulfate titration is significantly higher than the performance of more than 10 seconds in the national standard HG / T3778-2005. Furthermore, the pre-filming agent has few components, is phosphorus-free and zinc-free, meeting the increasingly stringent pollutant emission requirements. It solves the problem of large-scale discharge and replenishment of industrial enterprises after pre-filming while ensuring that the total phosphorus in the discharged wastewater meets the emission standards. It is particularly suitable for the treatment of circulating cooling water with low hardness and low alkalinity.

Description

Phosphate-free pre-filming agent and pre-filming method Technical Field

[0001] This invention relates to the field of pre-filming, and more specifically to phosphorus-free pre-filming agents and pre-filming methods. Background Technology

[0002] Pre-filming agents are commonly used when starting up industrial circulating cooling water systems, either during initial commissioning or after maintenance and cleaning. Pre-filming, as a crucial step in industrial water treatment technology, is an important means of improving the corrosion resistance of circulating water equipment. Currently, commonly used pre-filming agents on the market are mostly composites of polyphosphates and zinc salts. Typically, the ratio of sodium hexametaphosphate to zinc sulfate heptahydrate is 4:1.6, the dosage is 400-800 mg / L, the pre-filming pH value is 5.5-6.5, and the pre-filming time is 12-48 hours. The aforementioned pre-filming agents are used in large quantities, have high phosphorus content, and easily form calcium phosphate scale. After pre-filming, a large amount of wastewater needs to be discharged, and the discharged phosphorus has a significant impact on the biological system of wastewater treatment. In recent years, there have been new requirements for the direct discharge standards of water pollutants. Among them, GB 31570-2015 "Emission Standard of Pollutants from Petroleum Refining Industry" and GB 31571-2015 "Requirements for Emission Standard of Pollutants from Petrochemical Industry" require that, from July 1, 2017, the total phosphorus in the external wastewater of enterprises should be ≤1.0 mg / L and the total zinc ≤2.0 mg / L. For special emission areas, the total phosphorus limit is 0.5 mg / L. These stricter requirements for phosphorus and zinc emissions limit the application of phosphorus-based pre-filming agents, making the development and application of phosphorus-free pre-filming agents imperative. Summary of the Invention

[0003] The purpose of this invention is to overcome the above-mentioned problems existing in the prior art and to provide a phosphorus-free pre-filming agent and a pre-filming method.

[0004] To achieve the above objectives, the first aspect of the present invention provides a phosphorus-free pre-filming agent, the pre-filming agent comprising the reaction product of the compound shown in Formula I and the compound shown in Formula II, hydrolyzed polymaleic anhydride, and at least one azole compound.

[0005]

[0006] Where R1 is sodium or potassium, and R2 is... R3, R4 and R5 are each independently selected from alkyl groups that are H or C1-C4.

[0007] A second aspect of the present invention provides a method for pre-filming, the method comprising: contacting the object to be pre-filmed with the aforementioned pre-filming agent in the presence of water.

[0008] Through the above technical solution, the pre-filming agent provided by the present invention forms a distinct blue-purple film on the surface of the object to be pre-filmed, and the color development time of copper sulfate titration is significantly higher than the performance of more than 10s in the national standard HG / T3778-2005. Furthermore, the pre-filming agent has few components, is free of phosphorus and zinc, meets the increasingly stringent pollutant emission requirements, and solves the problem of large-scale discharge and replenishment of industrial enterprises after pre-filming while ensuring that the total phosphorus in the discharged wastewater meets the emission standards. It is especially suitable for the treatment of circulating cooling water with low hardness and low alkalinity. Detailed Implementation

[0009] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0010] The first aspect of the present invention provides a phosphorus-free pre-filming agent, the pre-filming agent comprising a reaction product of a compound of formula I and a compound of formula II, hydrolyzed polymaleic anhydride, and at least one azole compound;

[0011]

[0012] Where R1 is sodium or potassium, and R2 is... R3, R4, and R5 are each independently selected from H or C1-C4 alkyl groups. R3, R4, and R5 are each preferably H or C1 alkyl groups.

[0013] In this invention, to obtain better pre-filming effect, the weight ratio of the reaction product of the compound shown in Formula I and the compound shown in Formula II to the hydrolyzed polymaleic anhydride is preferably 1:0.4-5.4, and can be 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.4, or any two of the above values ​​within a range. The hydrolyzed polymaleic anhydride described in this invention may exist in solution form during actual use; the weight ratio of the hydrolyzed polymaleic anhydride in this application refers to the amount of solute.

[0014] In this invention, the preparation method of the reaction product may include: reacting the compound shown in Formula I with the compound shown in Formula II under acid catalysis, or directly mixing the compound shown in Formula I with the compound shown in Formula II in water to generate the product. The product after the reaction does not require the removal of any other components besides water and can be directly used as one of the components of the pre-filming agent of this application. The weight ratio of the reaction product of the compound shown in Formula I and the compound shown in Formula II in this application refers to the amount of solid content therein.

[0015] Preferably, the molar ratio of the residues of compound I to the residues of compound II in the reaction product of the compound shown in Formula I and the compound shown in Formula II is 1:0.15-6, and can be 1:0.15, 1:0.2, 1:0.4, 1:0.6, 1:0.8, 1:1, 1:1.5, 1:2, 1:0.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, or any two of the above values ​​within a range. The molar ratio of the compound shown in Formula I to the compound shown in Formula II can also be controlled to be 1:0.15-6 during the preparation process.

[0016] In this invention, the acid catalyst is preferably sulfuric acid and / or nitric acid. The molar ratio of the catalyst to the compound shown in Formula I, based on hydrogen ions, is 0.2-6:1, preferably 0.8-4:1.

[0017] Preferably, the reaction conditions include: the mixing is carried out at a temperature sufficient to evaporate the water, preferably the mixing is carried out under heating conditions of 100-180°C, and the mixing time is 2-10 hours.

[0018] In this invention, in order to obtain a better pre-filming effect, the weight ratio of the reaction product of the compound shown in Formula I and the compound shown in Formula II and at least one azole compound is preferably 1:0.02-0.4, and can be 1:0.02, 1:0.03, 1:0.04, 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, 1:0.1, 1:0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.25, 0.3, 0.35, 0.4 or any two of the above values ​​and values ​​within the range.

[0019] In this invention, in order to obtain better pre-filming effect, the at least one azole compound is preferably mercaptobenzothiazole and / or benzotriazole.

[0020] The inventors of this invention have discovered that the pre-filming effect is best when the molecular weight distribution of the reaction product of the compound shown in Formula I and the compound shown in Formula II is in the range of 300-700.

[0021] The inventors of this invention have discovered that the pre-filming effect is best when the relative molecular weight of the hydrolyzed polymaleic anhydride is 400-800; preferably, the limiting viscosity of the hydrolyzed polymaleic anhydride at 30°C is 0.06-0.1 dL / g.

[0022] According to a preferred embodiment of the present invention, the pre-filming agent is composed of the above-described components. Each component may be provided in the form of a solution or suspension, but its content or amount is calculated on a dry basis (solid content).

[0023] A second aspect of the present invention provides a method for pre-filming, the method comprising: contacting the object to be pre-filmed with the aforementioned pre-filming agent in the presence of water.

[0024] In this invention, to obtain a better pre-filming effect, the concentration of the reaction product of the compound shown in Formula I and the compound shown in Formula II in water is 60-150 mg / L, which can be any two values ​​within the range of 60 mg / L, 70 mg / L, 80 mg / L, 90 mg / L, 100 mg / L, 110 mg / L, 120 mg / L, 130 mg / L, 140 mg / L, 150 mg / L, or more. Preferably, the concentration of the hydrolyzed polymaleic anhydride is 45 mg / L-120 mg / L. The concentration can be any two values ​​of 45 mg / L, 50 mg / L, 60 mg / L, 70 mg / L, 80 mg / L, 90 mg / L, 100 mg / L, 110 mg / L, 120 mg / L or more, or values ​​within that range; more preferably, the concentration of at least one azole compound is 2-5 mg / L, which can be any two values ​​of 2 mg / L, 2.5 mg / L, 3 mg / L, 3.5 mg / L, 4 mg / L, 4.5 mg / L, 5 mg / L or more, or values ​​within that range.

[0025] In this invention, to obtain better pre-filming effect, the pH of the contact system is controlled to be 6.5-7.5. The contact conditions include: a temperature of 20-45℃, which can be any two of the following values: 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, or higher; and a contact time of 8-72 hours, which can be any two of the following values: 8h, 10h, 15h, 20h, 25h, 30h, 35h, 40h, 45h, 50h, 55h, 60h, 65h, 70h, 72h, or higher. Preferably, the pH is controlled by mixing with a pH adjuster. More preferably, the acidic adjuster is sulfuric acid and / or sulfamic acid. Even more preferably, the alkaline adjuster is sodium bicarbonate and / or sodium carbonate, which can adjust the pH without affecting the pre-filming effect.

[0026] In this invention, the pre-filming agent is more suitable for treating circulating cooling water with low hardness and low alkalinity. Preferably, the sum of the calcium hardness and total alkalinity of the water is less than 150 mg·L⁻¹. -1 The following can be 0 mg·L -1 10 mg·L -1 20 mg·L -1 30 mg·L -1 40 mg·L -1 50 mg·L -1 60 mg·L -1 70 mg·L -1 80 mg·L -1 90 mg·L -1 100 mg·L -1 110 mg·L -1 120 mg·L -1 130 mg·L -1 140 mg·L -1 150 mg·L -1 Or any two of the above values ​​within a range, preferably 20-130 mg·L. -1 More specifically, the chloride ion concentration in the water of the contact system is 10-50 mg / L. -1 The preferred pH is 6-8, and more preferably, the conductivity is 50-300 μs / cm.

[0027] Preferably, the surface of the material to be pre-coated is metal, such as copper, iron, zinc or aluminum.

[0028] In practical use, the water in this invention is generally industrial circulating cooling water. The pre-filming method of this invention can be used to add the pre-filming agent when starting up an industrial circulating cooling water system for the first time or after maintenance and cleaning.

[0029] The present invention also provides the application of the phosphorus-free pre-filming agent as described above in extending the color development time of copper sulfate titration.

[0030] The present invention will be described in detail below through examples. In the following preparation examples, the molecular weight of the reaction products was determined by mass spectrometry, and the scanning mode was FTMS-p ESI Full ms [100-1000].

[0031] In the following preparation example, the feed ratio of each monomer actually participating in the polymerization is determined by testing the content of unreacted monomers, and then the content of each structural unit in the polymer is determined. Since there is no monomer residue in the reaction product, the molar ratio of each monomer residue in the reaction product is equal to the molar ratio of the feed amount.

[0032] The hydrolytic polymaleic anhydride reagent was purchased from Shandong Taihe Technology Co., Ltd., and the standard for determining the solid content is GB / T10535-2014.

[0033] The water quality of the test water is shown in Table 1.

[0034] Table 1

[0035] Water quality, calcium hardness, total alkalinity, Cl - pH conductivity (water quality) 145 25 136.5 109 (water quality) 230 45 186.9 133 (water quality) 350 50 266.9 157 (water quality) 450 80 287.1 208 (water quality) 580 45 316.8 231 surface

[0036] Note: pH has no unit; conductivity is measured in μs / cm; all other units are measured in mg / L. Calcium hardness and total alkalinity are expressed as CaCO3, and the same applies below. The determination methods for each parameter are as follows: Calcium hardness: refer to standard GB / T 6910-2006; Total alkalinity: refer to standard GB / T15451-2006; Cl... - Reference standards: GB / T 15453-2008; pH value: GB / T 6920-1986; conductivity: GB / T 6908-2008. The water used in each test was diluted with or supplemented with the corresponding calcium hardness and alkalinity from surface water. Calcium hardness was supplemented with anhydrous CaCl2, calculated as CaCO3; alkalinity was supplemented with anhydrous sodium bicarbonate, calculated as CaCO3.

[0037] The methods for determining the solid content of the product obtained in the preparation examples include:

[0038] Weigh approximately 1g of the obtained product sample, accurate to 0.0002g, and place it in a pre-weighed flat weighing dish. Gently shake the dish to allow the sample to flow naturally, forming a uniform thin film on the bottom. Then place the dish in an electric drying oven and heat from room temperature to 120℃ for 4 hours. Weigh the dish every 0.5 hours until a constant weight is achieved. After constant weight, remove the dish, place it in a desiccator to cool to room temperature, and weigh it again.

[0039] The formula for calculating solid content is: Solid content = [(m2-m1) / m] × 100%

[0040] m2: Weight of the dried sample and weighing dish, in g;

[0041] m1: Net weight of the weighing dish, in g;

[0042] m: Mass of the sample taken, in grams.

[0043] Preparation Example 1

[0044] Preparation of the reaction product of compound I (R1 is sodium) and compound II (R3, R4 and R5 are all H): 32.7 g (0.15 mol) of compound I (R1 is sodium), 14.9 g (0.1 mol) of compound II (R3, R4 and R5 are all H) and 100 mL of water were added to a four-necked flask equipped with a stirrer, distillation apparatus and thermometer. Stirring was started to allow the compound I (R1 is sodium) and compound II (R3, R4 and R5 are all H) to fully dissolve and mix. Subsequently, 5g of concentrated sulfuric acid (containing 0.05mol of H2SO4) was added at 20℃, and the mixture was heated to 130℃ in an oil bath (dimethyl silicone oil) for 6 hours. 40g of water was distilled off, and the remaining liquid was cooled to obtain the reaction product of the compound shown in Formula I (R1 is sodium) and the compound shown in Formula II (R3, R4, and R5 are all H), which is product S1. Liquid chromatography was used to determine that no residual monomers (Formula I and Formula II) were found. Its solid content was 40% by weight, and its molecular weight distribution was in the range of 327-683.

[0045] Preparation Example 2

[0046] Preparation of the reaction product of compound I (R1 is sodium) and compound II (R3, R4 and R5 are all H): 32.7 g (0.15 mol) of compound I (R1 is sodium), 134.1 g (0.9 mol) of compound II (R3, R4 and R5 are all H) and 100 mL of water were added to a four-necked flask equipped with a stirrer, distillation apparatus and thermometer. Stirring was started to allow the compound I (R1 is sodium) and compound II (R3, R4 and R5 are all H) to be fully dissolved and mixed. Subsequently, 45g of concentrated sulfuric acid (containing 0.45mol of H2SO4) was added at 20℃, and the mixture was heated to 130℃ in an oil bath (dimethyl silicone oil) for 6 hours. 50g of water was distilled off, and the remaining liquid was cooled to obtain the reaction product of the compound shown in Formula I (R1 is sodium) and the compound shown in Formula II (R3, R4, and R5 are all H). This product is S2. Liquid chromatography was used to determine that no residual monomers (Formula I and Formula II) were found. Its solid content was 59.6% by weight, and its molecular weight was 327.

[0047] Preparation Example 3

[0048] Preparation of the reaction product of compound I (R1 is potassium) and compound II (R3, R4 and R5 are all H): 23.4 g (0.1 mol) of compound I (R1 is potassium), 2.3 g (0.015 mol) of compound II (R3, R4 and R5 are all H) and 100 mL of water were added to a four-necked flask equipped with a stirrer, distillation apparatus and thermometer. Stirring was started to allow the compound I (R1 is potassium) and compound II (R3, R4 and R5 are all H) to be fully dissolved and mixed. Subsequently, 3.15 g of concentrated nitric acid (containing 0.034 mol of HNO3) was added at 20 °C, and the mixture was heated to 110 °C in an oil bath (dimethyl silicone oil) for 2 h. 25 g of water was distilled off, and the remaining liquid was cooled to obtain the reaction product of the compound shown in Formula I (R1 is potassium) and the compound shown in Formula II (R3, R4, and R5 are all H). This product is S3. Liquid chromatography was used to determine that no residual monomers (Formula I and Formula II) were found. Its solid content was 22.8% by weight, and its molecular weight distribution was in the range of 327-683.

[0049] Preparation Example 4

[0050] Preparation of the reaction product of compound I (R1 is potassium) and compound II (R3, R4, and R5 are all CH3): 35.1 g (0.15 mol) of compound I (R1 is potassium), 19.3 g (0.1 mol) of compound II (R3, R4, and R5 are all CH3), and 100 mL of water were added to a four-necked flask equipped with a stirrer, distillation apparatus, and thermometer. Stirring was started to ensure complete dissolution and mixing of the two compounds. 9.3 g of concentrated nitric acid (containing 0.1 mol of HNO3) was added at 20 °C. The heating bath (heating medium being dimethyl silicone oil) containing the aforementioned flask was heated to 180°C and reacted for 6 hours. 55g of water was distilled off. The remaining liquid was cooled to obtain the reaction product of the compound shown in Formula I (R1 being potassium) and the compound shown in Formula II (R3, R4, and R5 being CH3). This product was S4. Liquid chromatography analysis showed no residual monomers (Formula I and Formula II). Its solid content was 44.2% by weight, and its molecular weight ranged from 365 to 700.

[0051] Preparation Example 5

[0052] Preparation of the reaction product of compound I (R1 is sodium) and compound II (R3, R4, and R5 are all CH3): 32.7 g (0.15 mol) of compound I (R1 is sodium), 19.3 g (0.1 mol) of compound II (R3, R4, and R5 are all CH3), and 100 mL of water were added to a four-necked flask equipped with a stirrer, distillation apparatus, and thermometer. Stirring was started to ensure complete dissolution and mixing of the two compounds. 9.3 g of concentrated nitric acid (containing 0.1 mol of HNO3) was added at 20 °C. The heating bath (heating medium being dimethyl silicone oil) containing the aforementioned flask was heated to 180°C and reacted for 6 hours. 50g of water was distilled off, and the remaining liquid was cooled to obtain the reaction product of compound I (R1 being sodium) and compound II (R3, R4, and R5 being CH3). This product is S5. Liquid chromatography analysis showed no residual monomers (Formula I and II), and its solid content was 44.5% by weight, with a molecular weight distribution in the range of 365-700.

[0053] Preparation Example 6

[0054] Preparation of the reaction product of potassium citrate and the compound shown in Formula II (R3, R4 and R5 are all H): 46.0 g (0.15 mol) of potassium citrate, 14.9 g (0.1 mol) of the compound shown in Formula II (R3, R4 and R5 are all H) and 100 mL of water were added to a four-necked flask equipped with a stirrer, distillation apparatus and thermometer. Stirring was started to allow the potassium citrate and the compound shown in Formula II (R3, R4 and R5 are all H) to be fully dissolved and mixed. Subsequently, 5g of concentrated sulfuric acid (containing 0.05mol of H2SO4) was added at 20℃, and the mixture was heated to 130℃ in an oil bath (dimethyl silicone oil) for 6 hours. 40g of water was distilled off, and the remaining liquid was cooled to obtain the reaction product of sodium citrate and the compound shown in Formula II (R3, R4, and R5 are all H), which is product S6. Liquid chromatography was used to determine that no residual monomers (potassium citrate and Formula II) were found. Its solid content was 42% by weight, and its molecular weight distribution was in the range of 343-692.

[0055] Preparation Example 7

[0056] Preparation of the reaction product of compound I (R1 is sodium) and ethanolamine: 32.7 g (0.15 mol) of compound I (R1 is sodium), 6.1 g (0.1 mol) of ethanolamine, and 100 mL of water were added to a four-necked flask equipped with a stirrer, distillation apparatus, and thermometer. Stirring was started to ensure complete dissolution and mixing of the compound I (R1 is sodium) and ethanolamine. Then, 5 g (containing 0.05 mol of H2SO4) of concentrated sulfuric acid was added at 20 °C. The mixture was heated to 130 °C in an oil bath (dimethyl silicone oil) and reacted for 6 h. 40 g of water was distilled off. The remaining liquid was cooled to obtain the reaction product of compound I (R1 is sodium) and ethanolamine, product S7. Liquid chromatography analysis showed no residual monomers (formula I and ethanolamine), and its solid content was 37% by weight, with a molecular weight distribution in the range of 338-663.

[0057] Example 1

[0058] Weigh 46.7g of S1 product with a solid content of 40% by weight (prepared according to Preparation Example 1), 16.7g of hydrolyzed polymaleic anhydride reagent (limiting viscosity of 0.08dl / g at 30℃, weight-average molecular weight of 695g / mol, and hydrolyzed polymaleic anhydride content of 55% by weight), and 1.3g of benzotriazole. Add 35.3g of water and shake well to obtain the required 100g of reagent.

[0059] The reagent was added to the test water to achieve a concentration of 300 mg / L, and then added to a 2 L beaker to obtain the cleaning pre-filming agent. A rotary pre-filming test was conducted at 25℃ for 24 hours. The test water was water quality 1 (Table 1), with pH controlled at 7.2 ± 0.2, and sodium bicarbonate as the pH adjuster. The phosphorus-free pre-filming agent was tested according to the national standard HG / T3778-2005 "Technical Rules for Chemical Cleaning and Pre-filming Treatment of Cooling Water Systems". The pre-filming material was carbon steel, grade 20#. Three new pre-filming plates were treated according to HG / T3523-2008 requirements, hung on the pre-filming rack of the rotary pre-filming apparatus, and then placed in a 2 L beaker containing the cleaning pre-filming agent. The rotation speed was 75 r / min. The film color and state test results are shown in Table 2.

[0060] Example 2

[0061] Weigh 23.3g of S2 product with a solid content of 59.6% by weight (prepared according to Preparation Example 2), 33.3g of hydrolyzed polymaleic anhydride reagent (limiting viscosity of 0.075dl / g at 30℃, weight-average molecular weight of 631g / mol, and hydrolyzed polymaleic anhydride content of 55% by weight), and 1g of benzotriazole. Add 42.0g of water and shake well to obtain 100g of the required reagent.

[0062] The reagent was added to the test water to achieve a concentration of 300 mg / L, and then added to a 2 L beaker to obtain the cleaning pre-filming agent. A rotary pre-filming test was conducted at 25℃ for 24 hours. The test water was water quality 2 from Table 1, with pH controlled at 6.8±0.2, and sodium bicarbonate was used as the pH adjuster. The phosphorus-free pre-filming agent was tested according to the national standard HG / T3778-2005 "Technical Rules for Chemical Cleaning and Pre-filming Treatment of Cooling Water Systems". The pre-filming material was carbon steel, grade 20#. Three new pre-filming plates were treated according to HG / T3523-2008 requirements, hung on the pre-filming rack of the rotary pre-filming apparatus, and then placed in a 2 L beaker containing the cleaning pre-filming agent. The rotation speed was 75 r / min. The film color and state test results are shown in Table 2.

[0063] Example 3

[0064] Weigh 30.0g of S3 product with a solid content of 22.8% by weight (prepared according to Preparation Example 3), 38.3g of hydrolyzed polymaleic anhydride reagent (limiting viscosity of 0.065dl / g at 30℃, weight-average molecular weight of 563g / mol, and hydrolyzed polymaleic anhydride content of 55% by weight), and 0.7g of benzotriazole. Add 31.0g of water and shake well to obtain the required 100g of reagent.

[0065] The reagent was added to the test water to achieve a concentration of 300 mg / L, and then added to a 2 L beaker to obtain the cleaning pre-filming agent. A rotary pre-filming test was conducted at 25℃ for 24 hours. The test water was water quality 3 (Table 1), with pH controlled at 7.0 ± 0.2. The pH adjuster was aminosulfonic acid. The phosphorus-free pre-filming agent was tested according to the national standard HG / T3778-2005 "Technical Rules for Chemical Cleaning and Pre-filming Treatment of Cooling Water Systems". The pre-filming material was carbon steel, grade 20#. Three new pre-filming plates were treated according to HG / T3523-2008 requirements and hung on the pre-filming rack of the rotary pre-filming apparatus. These plates were then placed in a 2 L beaker containing the cleaning pre-filming agent, and the rotation speed was 75 r / min. The film color and state test results are shown in Table 2.

[0066] Example 4

[0067] Weigh 20.0g of S4 product with a solid content of 44.2% by weight (prepared according to Preparation Example 4), 26.7g of hydrolyzed polymaleic anhydride reagent (limiting viscosity of 0.085dl / g at 30℃, weight-average molecular weight of 725g / mol, and hydrolyzed polymaleic anhydride content of 55% by weight), and 0.7g of benzotriazole. Add 51.7g of water and shake well to obtain the required 100g of reagent.

[0068] The reagent was added to the test water to achieve a concentration of 300 mg / L, and then added to a 2 L beaker to obtain the cleaning pre-filming agent. A rotary pre-filming test was conducted at a temperature of 25℃ for 24 hours. The test water was water quality 4 from Table 1, with the pH controlled at 6.7±0.2. The pH adjuster was aminosulfonic acid. The phosphorus-free pre-filming agent was tested according to the national standard HG / T3778-2005 "Technical Rules for Chemical Cleaning and Pre-filming Treatment of Cooling Water Systems". The pre-filming material of the pre-filming agent was carbon steel, grade 20#. Three new pre-filming agents were taken, treated according to the requirements of HG / T3523-2008, and hung on the pre-filming rack of the rotary pre-filming apparatus. Then, the pre-filming agent was placed in a 2 L beaker containing the cleaning pre-filming agent, and the rotation speed was 75 r / min. The test results of film color and state are shown in Table 2.

[0069] Example 5

[0070] Weigh 40g of S5 product with a solid content of 44.5% by weight (prepared according to Preparation Example 5), 30.0g of hydrolyzed polymaleic anhydride reagent (limiting viscosity of 0.095dl / g at 30℃, weight-average molecular weight of 772g / mol, and hydrolyzed polymaleic anhydride content of 55% by weight), and 1.0g of benzotriazole. Add 29.0g of water and shake well to obtain the required 100g of reagent.

[0071] The reagent was added to the test water to achieve a concentration of 300 mg / L, and then added to a 2 L beaker to obtain the cleaning pre-filming agent. A rotary pre-filming test was conducted at 25℃ for 24 hours. The test water was water quality 5 (Table 1), with pH controlled at 7.3 ± 0.2. The pH adjuster was aminosulfonic acid. The phosphorus-free pre-filming agent was tested according to the national standard HG / T3778-2005 "Technical Rules for Chemical Cleaning and Pre-filming Treatment of Cooling Water Systems". The pre-filming material was carbon steel, grade 20#. Three new pre-filming plates were treated according to HG / T3523-2008 requirements, hung on the pre-filming rack of the rotary pre-filming apparatus, and then placed in a 2 L beaker containing the cleaning pre-filming agent. The rotation speed was 75 r / min. The film color and state test results are shown in Table 2.

[0072] Example 6

[0073] The method was the same as in Example 1, except that the amount of hydrolyzed polymaleic anhydride was 8.4 g and the amount of water was 43.6 g. The experimental results are shown in Table 2.

[0074] Example 7

[0075] The method was the same as in Example 1, except that the amount of benzotriazole was 9.3 g and the amount of water was 27.3 g. The experimental results are shown in Table 2.

[0076] Comparative Example 1

[0077] The method was followed as in Example 1, except that product S1 was not added, and the amount of hydrolyzed polymaleic anhydride was 60g, benzotriazole was 4.7g, and water was 35.3g. The test results are shown in Table 2.

[0078] Comparative Example 2

[0079] The method was followed as in Example 1, except that hydrolyzed polymaleic anhydride was not added. The amount of product S1 was 70g, benzotriazole was 1.9g, and water was 28.1g. The test results are shown in Table 2.

[0080] Comparative Example 3

[0081] Following the method of Example 1, except that benzotriazole was not added, the S1 product was 50.2 g, the hydrolyzed polymaleic anhydride was 17.9 g, and the water was 31.9 g. The test results are shown in Table 2.

[0082] Comparative Example 4

[0083] The method was followed in Example 1, except that the hydrolyzed polymaleic anhydride was replaced with maleic acid-acrylic acid copolymer (weight-average molecular weight 616 g / mol, Shandong Taihe Technology Co., Ltd.). The experimental results are shown in Table 2.

[0084] Comparative Example 5

[0085] The method was the same as in Example 1, except that benzotriazole was replaced with hexamethylenetetramine. The test results are shown in Table 2.

[0086] Comparative Example 6

[0087] The method of Example 1 was followed, except that product S1 was replaced with product S6 from Preparation Example 6. The test results are shown in Table 2.

[0088] Comparative Example 7

[0089] The method is the same as in Example 1, except that product S1 is replaced with product S7 from Preparation Example 7.

[0090] Test case

[0091] (1) After the pre-filming is completed, take out the test pieces, and dry one of them with a hair dryer. According to the requirements of HG / T3778-2005 "Technical Rules for Chemical Cleaning and Pre-filming Treatment of Cooling Water System", the time difference of the membrane's reaction with copper sulfate solution droplets should be ≥10 seconds. The color development time of saturated copper sulfate is shown in Table 2.

[0092] (2) After the other two test pieces are taken out, record the weight of the test pieces before and after the pre-filming, and calculate the average corrosion rate. The corrosion rate is shown in Table 2.

[0093] The formula for calculating the average corrosion rate is:

[0094] F = (C × △W) / (A × T × ρ)

[0095] C: Calculation constant, in mm / a units, C = 8.76 × 10⁻⁶ 7 ;

[0096] △W: Corrosion weight loss (g) of the specimen;

[0097] A: Specimen area (cm²) 2 );

[0098] T: Corrosion test time (h);

[0099] ρ: Density of the specimen material (kg / m³) 3 ).

[0100] Table 2

[0101] Number | Saturated Copper Sulfate Color Development Time / s | Film Color and State | Corrosion Rate / (mm / a) | Example 1 | 43.0 | Continuous Uniform Blue-Purple Film | 0.015 | Example 2 | 40.8 | Continuous Uniform Blue Film | 0.018 | Example 3 | 28.3 | Blue Film | 0.030 | Example 4 | 35.8 | Blue-Purple Film | 0.023 | Example 5 | 45.3 | Continuous Uniform Blue-Purple Film | 0.015 | Example 6 | 8.8 | No Obvious Film | 0.069 | Example 7 | 5.6 | Discontinuous Pale Blue Film | 0.056 | Comparative Example 1 | 4.5 | No Obvious Film | 0.102 | Comparative Example 2 | 3.7 | No Obvious Film | 0.079 | Comparative Example 3 | 7.9 | No Obvious Film | 0.065 | Comparative Example 4 | 5.3 | No Obvious Film | 0.047 | Comparative Example 5 | 3.9 | No Obvious Film | 0.081 | Comparative Example 6 | 6.6 | No Obvious Film | 0.055 | Comparative Example 7 | 8.7 | No Obvious Film | 0.106 surface

[0102] The results show that, using the embodiments of the present invention, the time difference between the pre-film formed by the pre-filming agent and the reaction of copper sulfate solution droplets is greater than the minimum of 10 seconds specified in HG / T3778-2005 "Technical Rules for Chemical Cleaning and Pre-filming Treatment of Cooling Water Systems". The effect is significantly better than the requirements of HG / 3778-2005, with a lower corrosion rate and better pre-filming effect.

[0103] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A phosphorus-free pre-filming agent, characterized in that, The phosphorus-free pre-filming agent contains: the reaction product of the compound shown in Formula I and the compound shown in Formula II, hydrolyzed polymaleic anhydride, and at least one azole compound; Equation I; Formula II; where R1 is sodium or potassium, and R2 is... R3, R4, and R5 are each independently selected from alkyl groups that are H or C1-C4; wherein, the molar ratio of the residues of compound I to the residues of compound II in the reaction product of the compound shown in Formula I and the compound shown in Formula II is 1:0.15-6; the molecular weight distribution of the reaction product of the compound shown in Formula I and the compound shown in Formula II is in the range of 300-700; wherein, the weight ratio of the reaction product of the compound shown in Formula I and the compound shown in Formula II, hydrolyzed polymaleic anhydride, and at least one azole compound is 1:0.8-5.4:0.03-0.

2.

2. The phosphorus-free pre-filming agent according to claim 1, wherein, The at least one azole compound is mercaptobenzothiazole and / or benzotriazole.

3. The phosphorus-free pre-filming agent according to claim 1 or 2, wherein, The hydrolyzed polymaleic anhydride has a weight-average molecular weight of 400-800 g / mol; and / or, the hydrolyzed polymaleic anhydride has a limiting viscosity of 0.06-0.1 dL / g at 30°C.

4. A pre-filming method, characterized in that, The method comprises: contacting the material to be pre-coated with the phosphorus-free pre-coating agent according to any one of claims 1-3 in the presence of water.

5. The method according to claim 4, wherein, The pH of the contact system is controlled to be 6.5-7.5; And / or, the contact conditions include: a temperature of 20-45°C and a time of 8-72 hours; And / or, the concentration of the reaction product of the compound shown in Formula I and the compound shown in Formula II in water is 60-150 mg / L.

6. The method according to claim 4 or 5, wherein, The sum of the calcium hardness and total alkalinity of the water is less than 150 mg·L⁻¹. -1 The following applies: and / or, the surface of the material to be pre-coated is metal.

7. The method according to claim 5, wherein, The pH of the contact system is controlled by mixing it with a pH adjuster, which is either an acidic or alkaline pH adjuster.

8. The method according to claim 7, wherein, The acidity regulator is sulfuric acid and / or aminosulfonic acid; and / or, the alkalinity regulator is sodium bicarbonate and / or sodium carbonate.

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