High-hardness water composite scale and corrosion inhibitor and preparation method thereof

Abstract

The invention discloses a high-hardness water composite scale and corrosion inhibitor and a preparation method thereof, and belongs to the technical field of circulating cooling water treatment.The preparation method comprises the steps that firstly, branched polyethyleneimine amic acid is synthesized through a ring-opening amidation reaction of maleic anhydride and branched polyethyleneimine, then the branched polyethyleneimine amic acid serves as a macromolecular core and is subjected to amidation polycondensation with ethidene diamine, and the high-hardness water composite scale and corrosion inhibitor is obtained. A hyperbranched polyamide-amine scale inhibitor is obtained, polysuccinimide is subjected to ring opening under the alkaline condition and grafted with sodium alginate, a PASP / SA corrosion inhibitor is obtained, then the hyperbranched polyamide-amine scale inhibitor, the PASP / SA corrosion inhibitor and sodium bentonite are dispersed in a cyclohexane solution together, petroleum ether is dropwise added to trigger solvent phase separation, a compact coating film is formed, and the scale inhibitor is prepared. The high-hardness water composite scale and corrosion inhibitor is obtained; and under the conditions of high scale inhibition rate and high corrosion inhibition rate, long-acting stable protection in a high-hardness water environment is realized, and the operation and maintenance cost is remarkably reduced.

Description

Technical Field

[0001] This invention belongs to the field of circulating cooling water treatment technology, specifically relating to a high-hardness water composite scale and corrosion inhibitor and its preparation method. Background Technology

[0002] High-hardness water composite scale and corrosion inhibitors are a type of multifunctional water treatment agent designed for high-hardness water environments with a total hardness typically exceeding 250 mg / L (calculated as calcium carbonate) and rich in calcium, magnesium, and other easily scale-forming ions. They are formulated by scientifically compounding scale inhibitors, corrosion inhibitors, and additives.

[0003] The initial purpose of this preparation was to address the safety hazards caused by scale buildup in equipment due to high-hardness water in industrial circulating cooling water, boiler feedwater, and oilfield injection scenarios, which reduces heat transfer efficiency, clogs pipes, and corrodes equipment. It inhibits calcium and magnesium salt deposition through chelation and lattice distortion, and uses passivation and adsorption films to synergistically protect the metal surface, achieving scale inhibition and corrosion inhibition effects. Based on compounding technology, it is prepared through component screening, room temperature stirring and mixing, pH adjustment, stabilization treatment, and performance verification. Some can be spray-dried into solid products. However, existing technical solutions still have problems such as insufficient component compatibility and stability, need to improve synergistic efficiency, and environmental risks such as phosphorus / heavy metal content.

[0004] Chinese invention patent application CN111039422A discloses a composite scale and corrosion inhibitor suitable for high-hardness water and its application. The core component is first prepared by catalytic condensation reaction of sodium / potassium gluconate and aspartic acid, and then compounded with other raw materials to obtain the composite scale and corrosion inhibitor. This agent is specifically used to treat high-hardness and high-alkali circulating cooling water, achieving efficient scale and corrosion inhibition while keeping the total phosphorus content of the system below 1 mg / L.

[0005] However, since the components are added directly in a free state, they are easily consumed or deactivated by water flow, temperature changes and pH fluctuations, and cannot achieve the slow-release function. They need to be added continuously or frequently, which limits the actual application effect and increases the operating cost. Summary of the Invention

[0006] The purpose of this invention is to provide a high-hardness water composite scale and corrosion inhibitor and its preparation method. By combining microencapsulation with solvent phase separation, ethyl cellulose is used to form a dense coating film on the surface of composite particles composed of hyperbranched polyamide-amine scale inhibitor, PASP / SA corrosion inhibitor and bentonite carrier, constructing a "core-shell" slow-release system. This system can effectively control the slow and sustained release of internal active ingredients, enhance the agent's resistance to consumption in high-hardness water environments, significantly extend the protection cycle, and reduce operating costs. It is particularly suitable for circulating cooling water systems with high hardness, high alkalinity, high concentration ratio or intermittent operation.

[0007] The objective of this invention can be achieved through the following technical solutions: A method for preparing a high-hardness water composite scale and corrosion inhibitor comprises the following steps: Step 1: First, a branched polyethyleneimine ammonium acid with a segmented carboxyl group is synthesized by ring-opening amidation reaction of maleic anhydride and branched polyethyleneimine. Then, using this as a macromolecular core, it is subjected to amidation polycondensation with ethylenediamine to obtain a hyperbranched polyamide-amine scale inhibitor.

[0008] Step 2: Under alkaline conditions, polysuccinimide is ring-opened and grafted copolymerized with sodium alginate to obtain PASP / SA corrosion inhibitor.

[0009] Step 3: The hyperbranched polyamide-amine scale inhibitor, PASP / SA corrosion inhibitor, and sodium bentonite carrier are dispersed together in a cyclohexane solution containing ethyl cellulose, Span-80, and polydimethylsiloxane. The solvent phase separation is triggered by the dropwise addition of petroleum ether, which causes ethyl cellulose to precipitate and form a dense coating film on the surface of the composite particles, thereby obtaining a high hardness water composite scale and corrosion inhibitor with a microencapsulated slow-release structure.

[0010] The above PASP stands for polyaspartic acid, and SA stands for sodium alginate.

[0011] Furthermore, the specific preparation steps for branched polyvinyliminolic acid are as follows: Maleic anhydride and N,N-dimethylformamide were added to a three-necked flask and stirred until evenly dispersed. A 50 wt% polyethyleneimine DMF mixed solution was added dropwise through a constant pressure dropping funnel. After the addition was complete, the reaction was stirred for 12-14 hours. Most of the DMF solvent was removed by rotary evaporator. The obtained product was washed with anhydrous ethanol, precipitated, and dried under vacuum to obtain branched polyethyleneimine ammonium acid.

[0012] Furthermore, the ratio of maleic anhydride, N,N-dimethylformamide and polyethyleneimine DMF mixed solution is 4.9-8.2g: 50-80mL: 16-20g.

[0013] Furthermore, the specific preparation steps of the hyperbranched polyamide-amine scale inhibitor are as follows: Deionized water, branched polyvinylimino acid, and sodium hydroxide were added to a three-necked flask equipped with a thermometer and a reflux condenser. The mixture was stirred at room temperature until clear, then ethylenediamine was added, and the mixture was stirred and refluxed at 80-90°C for 6-8 hours to carry out the polymerization reaction. After the reaction was completed, the mixture was rotary evaporated at 60-70°C, freeze-dried to constant weight, ground, and passed through a 200-mesh sieve to obtain the hyperbranched polyamide-amine scale inhibitor.

[0014] Furthermore, the ratio of deionized water, branched polyvinylimino acid, sodium hydroxide, and ethylenediamine is 80-100mL: 5-8g: 0.48-0.62g: 0.36-0.48g.

[0015] Furthermore, the specific preparation steps for the PASP / SA corrosion inhibitor are as follows: Polysuccinimide was added to deionized water and stirred until a suspension was formed. Then, sodium alginate and sodium hydroxide solution were slowly added and reacted at 60-70℃ for 4-6 hours. The pH was adjusted to neutral with hydrochloric acid, the product was precipitated with ethanol, filtered, washed, and vacuum dried to constant weight to obtain PASP / SA corrosion inhibitor.

[0016] Furthermore, the ratio of polysuccinimide, deionized water, sodium alginate, and sodium hydroxide solution is 0.98-1.52g: 20-50mL: 0.5-0.8g: 6-8mL.

[0017] Furthermore, the specific preparation steps of the high-hardness water composite scale and corrosion inhibitor are as follows: Ethyl cellulose powder and cyclohexane were added to a flask, along with Span-80 and polydimethylsiloxane. The mixture was heated to 75-85°C and stirred until completely dissolved. Then, hyperbranched polyamide-amine scale inhibitor, PASP / SA corrosion inhibitor, and sodium bentonite were added. The mixture was stirred for 30-40 minutes and allowed to cool naturally to room temperature. Petroleum ether was slowly added dropwise through a constant pressure funnel. The mixture was then filtered. The filter cake was washed 2-4 times with petroleum ether and 2-4 times with distilled water. The cake was then dried at room temperature to obtain a high-hardness water composite scale and corrosion inhibitor.

[0018] Furthermore, the ratio of ethyl cellulose powder, cyclohexane, Span-80, polydimethylsiloxane, hyperbranched polyamide-amine scale inhibitor, PASP / SA corrosion inhibitor, sodium bentonite, and petroleum ether is 2-3g: 70-100mL: 2-3g: 40-50mL: 1-2g: 1-2g: 2-3g: 70-100mL.

[0019] The beneficial effects of this invention are: 1. This invention utilizes an integrated "loading-coating-slow-release" structural design to prepare a green, long-lasting composite scale and corrosion inhibitor for high-hardness water. Firstly, in terms of active ingredient design, a phosphorus-free and zinc-free hyperbranched polyamide-amine scale inhibitor and a PASP / SA corrosion inhibitor are designed. The former is formed by ring-opening amidation modification of branched polyethyleneimine with maleic anhydride, followed by condensation crosslinking with ethylenediamine, resulting in a dense carboxyl group and hyperbranched structure. The latter is obtained by graft copolymerization of polyaspartic acid segments generated from the ring-opening of polysuccinimide with sodium alginate, possessing both adsorption and film-forming functions. The synergistic effect of these two agents eliminates the environmental risks of phosphorus and zinc emissions at the source. In terms of formulation, sodium-based bentonite is used as a loading carrier to immobilize the above active ingredients. Then, through solvent phase separation, ethyl cellulose is used to form a dense coating film on the surface of the composite particles, constructing a core-shell slow-release structure. By transforming the traditional "instantaneous addition" of reagents into "long-lasting sustained release," the frequency of addition and operating costs are significantly reduced, making it particularly suitable for intermittent operation and high concentration systems.

[0020] This solution integrates efficient scale and corrosion inhibition with controlled release characteristics into a single microcapsule formulation, simplifying on-site dosing and management processes, and providing a high-performance, environmentally friendly, and cost-effective solution for high-hardness, high-alkali circulating cooling water systems.

[0021] 2. The hyperbranched polyamide-amine scale inhibitor of this invention, with its unique three-dimensional hyperbranched structure and densely distributed terminal carboxyl and amine groups, achieves a "stereoscopic synergistic scale inhibition effect." Steric hindrance effectively inhibits scale crystal growth and aggregation, while the synergistic effect of multiple functional groups efficiently chelates various scale-forming ions such as calcium and magnesium, exhibiting broad-spectrum and highly efficient scale inhibition performance against different scale types such as calcium carbonate, calcium phosphate, and calcium sulfate. Simultaneously, this structure possesses good water solubility and chemical stability, enabling it to adapt to harsh environments with high water temperatures and pH fluctuations.

[0022] 3. The PASP / SA corrosion inhibitor in this invention is formed by graft copolymerization of polyaspartic acid and sodium alginate. Its unique molecular structure combines the strong chemical adsorption capacity of polyaspartic acid segments on metal surfaces with the physical film-forming properties of sodium alginate segments, forming a dual corrosion inhibition mechanism of "adsorption anchoring-barrier reinforcement". This constructs a denser, stronger and more complete protective film on the metal surface. The corrosion inhibitor also has good environmental adaptability, is resistant to water quality fluctuations and high temperatures, and is phosphorus-free, zinc-free and biodegradable. It can interact with hyperbranched polyamide-amine scale inhibitors through functional group interaction to produce a synergistic protective effect and is easily loaded and encapsulated by carriers. It is a key active component for achieving long-term slow release and comprehensive corrosion protection. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments in the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1: A method for preparing a high-hardness water composite scale and corrosion inhibitor, comprising the following steps: S1: Add 4.9 g of maleic anhydride and 50 mL of N,N-dimethylformamide to a three-necked flask, stir and disperse evenly. Add 16 g of 50 wt% polyethyleneimine DMF mixed solution dropwise through a constant pressure dropping funnel. After the addition is complete, continue stirring and react for 12 h. Remove most of the DMF solvent by rotary evaporator. Wash the obtained product with anhydrous ethanol to precipitate. Dry the precipitate under vacuum to obtain branched polyethyleneimine ammonium acid.

[0025] By utilizing the anhydride group in maleic anhydride to undergo a ring-opening amidation reaction with a large number of primary amine groups on the branched polyethyleneimine molecular chain, in DMF solvent, the anhydride ring is opened by nucleophilic attack of the amine group to form an amide bond (-CONH-), and a carboxyl group (-COOH) is generated at each reaction site, finally yielding a branched polyethyleneimine ammonium acid with a branched structure, amide bond and multiple terminal carboxyl groups.

[0026] S2: Add 80 mL of deionized water, 5 g of branched polyvinylimine acid, and 0.48 g of sodium hydroxide to a three-necked flask equipped with a thermometer and a reflux condenser. Stir until clear at room temperature, add 0.36 g of ethylenediamine, and stir under reflux at 80 °C for 6 h of polymerization. After the reaction is complete, evaporate by rotary evaporation at 60 °C, freeze dry to constant weight, grind the product, and pass it through a 200-mesh sieve to obtain hyperbranched polyamide-amine scale inhibitor.

[0027] Using branched polyvinylimino acid with multiple terminal carboxyl groups as the macromolecular core, and ethylenediamine with bifunctional groups as the linker arm, the molecular structure is further extended and cross-linked through amidation polycondensation reaction between carboxyl groups and primary amine groups.

[0028] S3: Add 0.98g of polysuccinimide to 20mL of deionized water, stir until a suspension is formed, then slowly add 0.5g of sodium alginate and 6mL of sodium hydroxide solution, react at 60℃ for 4h, adjust the pH to neutral with hydrochloric acid, precipitate the product with ethanol, filter, wash the precipitated product three times with ethanol, and vacuum dry at 60℃ to constant weight to obtain PASP / SA corrosion inhibitor.

[0029] Under alkaline conditions, the polyaspartic acid active segments generated by the ring-opening of polysuccinimide undergo a dehydration condensation reaction with the hydroxyl groups on the sodium alginate molecular chain to form a PASP-SA graft copolymer linked by covalent bonds. Sodium hydroxide drives both the ring-opening of polysuccinimide and activates the hydroxyl groups of sodium alginate.

[0030] S4: Add 2g of ethyl cellulose powder and 70mL of cyclohexane to a flask, add 2g of Span-80 and 40mL of polydimethylsiloxane, heat to 75℃ and stir until completely dissolved, then add 1g of hyperbranched polyamide-amine scale inhibitor, 1g of PASP / SA corrosion inhibitor and 2g of sodium bentonite, continue stirring for 30min, cool naturally to room temperature, slowly add 70mL of petroleum ether dropwise through a constant pressure funnel, filter, wash the filter cake twice with petroleum ether and twice with distilled water, and dry at room temperature to obtain a high hardness water composite scale and corrosion inhibitor.

[0031] By using the solvent phase separation method, petroleum ether, a poor solvent, is added dropwise to the cyclohexane good solvent system of ethyl cellulose to reduce the system's solubility for ethyl cellulose, inducing its precipitation and deposition on the surface of dispersed supported composite scale and corrosion inhibitor particles, forming a dense ethyl cellulose coating film.

[0032] Example 2: A method for preparing a high-hardness water composite scale and corrosion inhibitor, comprising the following steps: S1: Add 6.5g of maleic anhydride and 65mL of N,N-dimethylformamide to a three-necked flask, stir and disperse evenly, and add 18g of 50wt% polyethyleneimine DMF mixed solution dropwise through a constant pressure dropping funnel. After the addition is complete, continue stirring and reacting for 13h. Remove most of the DMF solvent by rotary evaporator, wash the obtained product with anhydrous ethanol, precipitate, and dry under vacuum to obtain branched polyethyleneimine ammonium acid.

[0033] S2: Add 90 mL of deionized water, 6.5 g of branched polyvinylimine acid, and 0.55 g of sodium hydroxide to a three-necked flask equipped with a thermometer and a reflux condenser. Stir until clear at room temperature, add 0.42 g of ethylenediamine, and stir under reflux at 85 °C for 7 h of polymerization. After the reaction is complete, evaporate by rotary evaporation at 65 °C, freeze dry to constant weight, grind, and pass through a 200-mesh sieve to obtain hyperbranched polyamide-amine scale inhibitor.

[0034] S3: Add 1.25g of polysuccinimide to 35mL of deionized water, stir until a suspension is formed, then slowly add 0.65g of sodium alginate and 7mL of sodium hydroxide solution, react at 65℃ for 5h, adjust the pH to neutral with hydrochloric acid, precipitate the product with ethanol, filter, wash 3 times with ethanol, and vacuum dry at 65℃ to constant weight to obtain PASP / SA corrosion inhibitor.

[0035] S4: Add 2.5g of ethyl cellulose powder and 85mL of cyclohexane to a flask, add 2.5g of Span-80 and 45mL of polydimethylsiloxane, heat to 80℃ and stir until completely dissolved, then add 1.5g of hyperbranched polyamide-amine scale inhibitor, 1.5g of PASP / SA corrosion inhibitor and 2.5g of sodium bentonite, continue stirring for 35min, cool naturally to room temperature, slowly add 85mL of petroleum ether dropwise through a constant pressure funnel, filter, wash the filter cake three times with petroleum ether and three times with distilled water, and air dry at room temperature to obtain a high hardness water composite scale and corrosion inhibitor.

[0036] Example 3: A method for preparing a high-hardness water composite scale and corrosion inhibitor, comprising the following steps: S1: Add 8.2g of maleic anhydride and 80mL of N,N-dimethylformamide to a three-necked flask, stir and disperse evenly, and add 20g of 50wt% polyethyleneimine DMF mixed solution dropwise through a constant pressure dropping funnel. After the addition is complete, continue stirring and reacting for 14h. Remove most of the DMF solvent by rotary evaporator, wash the obtained product with anhydrous ethanol, precipitate, and dry under vacuum to obtain branched polyethyleneimine ammonium acid.

[0037] S2: Add 100 mL of deionized water, 8 g of branched polyvinylimine acid, and 0.62 g of sodium hydroxide to a three-necked flask equipped with a thermometer and a reflux condenser. Stir until clear at room temperature, add 0.48 g of ethylenediamine, stir and reflux at 90 °C for 8 h of polymerization. After the reaction is complete, evaporate by rotary evaporation at 70 °C, freeze dry to constant weight, grind, and pass through a 200 mesh sieve to obtain hyperbranched polyamide-amine scale inhibitor.

[0038] S3: Add 1.52g of polysuccinimide to 50mL of deionized water, stir until a suspension is formed, then slowly add 0.8g of sodium alginate and 8mL of sodium hydroxide solution, react at 70℃ for 6h, adjust the pH to neutral with hydrochloric acid, precipitate the product with ethanol, filter, wash 3 times with ethanol, and vacuum dry at 70℃ to constant weight to obtain PASP / SA corrosion inhibitor.

[0039] S4: Add 3g of ethyl cellulose powder and 100mL of cyclohexane to a flask, add 3g of Span-80 and 50mL of polydimethylsiloxane, heat to 85℃ and stir until completely dissolved, then add 2g of hyperbranched polyamide-amine scale inhibitor, 2g of PASP / SA corrosion inhibitor and 3g of sodium bentonite, continue stirring for 40min, cool naturally to room temperature, slowly add 100mL of petroleum ether through a constant pressure funnel, filter, wash the filter cake 4 times with petroleum ether and 4 times with distilled water, and dry at room temperature to obtain a high hardness water composite scale and corrosion inhibitor.

[0040] In Implementations 1-3, the polysuccinimide was selected from Wuhan Shuer Biotechnology Co., Ltd., CAS No. 5608-40-6, model number shuer6322; the polydimethylsiloxane was selected from Jinan Sigang Chemical Co., Ltd.; the sodium bentonite was selected from Lingshou County Dongfeng Mineral Processing Plant, with a particle size of 800 mesh μm; the petroleum ether was selected from Jinan Zekuan Chemical Co., Ltd., CAS No. 60-90; and the remaining raw materials were all commercially available products.

[0041] Comparative Example 1: The difference from Example 1 is that steps S1, S2 and S3 are omitted, and commercially available polyacrylic acid is used instead of hyperbranched polyamide-amine scale inhibitor and commercially available polyaspartic acid is used instead of PASP / SA corrosion inhibitor. The remaining steps remain unchanged to prepare a high-hardness water composite scale and corrosion inhibitor.

[0042] Comparative Example 2: The difference from Example 1 is that step S4 is omitted. The hyperbranched polyamide-amine scale inhibitor synthesized in step S2, the PASP / SA corrosion inhibitor synthesized in step S3, and sodium bentonite are simply mixed in a dry physical powder. The remaining steps remain unchanged to prepare a high-hardness water composite scale and corrosion inhibitor.

[0043] Comparative Example 3: The difference from Example 1 is that the solvent phase separation method in S4 is replaced by the conventional spray drying method. The active ingredient is dispersed in a solution of ethyl cellulose and granulated and coated by spray drying equipment. The remaining steps remain unchanged to prepare a high hardness water composite scale and corrosion inhibitor.

[0044] A comparative test was conducted on the scale inhibition and corrosion inhibition effects of the high-hardness water composite scale inhibitors and corrosion inhibitors prepared in Examples 1-3 and Comparative Examples 1-3: Scale inhibition test: All tests used water samples with a calcium ion concentration of 1220.5 mg / L, pH of 6.1, and turbidity of 31 NTU. The reagent concentration was uniformly 30 mg / L. The system was concentrated three times by constant temperature static evaporation at 80℃. After the test, the samples were filtered, dried, and the mass of the sediment was weighed. The formula is: Scale inhibition rate = (mass of sediment in blank group - mass of sediment in experimental group) / mass of sediment in blank group × 100%; the higher the scale inhibition rate, the better the scale inhibition effect.

[0045] Corrosion inhibition test: The rotating plate method was used, and the test was conducted continuously for 216 hours at 50℃ and 75 rpm. After the test, the corrosion products were removed by standard acid washing, and the weight loss of the plate was measured. The formula is: Corrosion rate = (mass of the plate before the test - mass of the plate after the test) / (surface area of ​​the plate × test time) × conversion factor; Corrosion inhibition rate = (corrosion rate of the blank group - corrosion rate of the experimental group) / corrosion rate of the blank group × 100%; The higher the corrosion inhibition rate, the better the corrosion inhibition effect.

[0046] The results are shown in Table 1: Table 1 Performance Test Results of Composite Scale and Corrosion Inhibitor for High Hardness Water

[0047] As shown in Table 1, the high-hardness water composite scale and corrosion inhibitors prepared in Examples 1-3 of this invention have significantly better performance than those in Comparative Examples 1-3. By using branched polyethyleneimine as a skeleton, performing ring-opening amidation modification with maleic anhydride, and then performing polycondensation crosslinking with ethylenediamine, a hyperbranched polyamide-amine scale inhibitor was synthesized, laying the molecular foundation for the efficient dispersion of calcium, magnesium, and other ions. Then, by ring-opening polysuccinimide and grafting it with sodium alginate, a PASP / SA corrosion inhibitor with carboxyl adsorption and film-forming properties was prepared, enhancing the interfacial protection ability on the metal surface. Finally, a microcapsule structure with controllable release was constructed, achieving long-term stable protection in high-hardness water environments with high scale inhibition rate and high corrosion inhibition rate, significantly reducing operation and maintenance costs.

[0048] The scale inhibition rates in Comparative Example 1 were significantly reduced, possibly because commercially available polyacrylic acid and polyaspartic acid have ordinary branched structures. The carboxyl group density, spatial configuration, and molecular weight distribution on their molecular chains are significantly less than those of the hyperbranched polyamide-amine and PASP / SA graft copolymer synthesized in this invention. The functional polymer synthesized in this invention has a higher degree of branching, denser terminal carboxyl groups, and stereochelation and steric hindrance effects brought about by grafting sodium alginate chains, resulting in stronger lattice distortion and dispersion stabilization capabilities against various calcium scales.

[0049] The significantly increased corrosion rate and markedly decreased corrosion inhibition rate in Comparative Example 2 may be due to the lack of an ethyl cellulose slow-release coating. The uncoated hyperbranched polyamide-amine scale inhibitor and PASP / SA corrosion inhibitor dissolved directly and rapidly in the water after addition. Although they could form a certain degree of protection in the initial stage, they could not withstand long-term water flow, temperature fluctuations, and ion exchange consumption. Their effective concentration decayed rapidly, making it difficult to maintain a durable and complete protective film on the metal surface. This led to a sharp decline in corrosion inhibition performance and increased corrosion in the later stages.

[0050] In Comparative Example 3, the scale inhibition rate, corrosion rate, and corrosion inhibition rate all decreased. This may be because spray drying, as a conventional coating process, may cause the coating layer to form too quickly due to its instantaneous high-temperature drying characteristics. The density and uniformity of the coating layer are not as good as the film formed by the gradual precipitation under mild conditions in the solvent phase separation method. There may be more micropores or defects, resulting in the initial burst release of active ingredients. High temperature may also have a slight impact on the structure or functional groups of some heat-sensitive active components.

[0051] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A method for preparing a high-hardness water composite scale and corrosion inhibitor, characterized in that, Prepared by the following steps: Step 1: First, through the ring-opening amidation reaction of maleic anhydride and branched polyethyleneimine, a branched polyethyleneimine ammonium acid with a segmented carboxyl group is synthesized as a macromolecular core, which is then subjected to amidation polycondensation with ethylenediamine to obtain a hyperbranched polyamide-amine scale inhibitor. Step 2: Under alkaline conditions, polysuccinimide is ring-opened and grafted copolymerized with sodium alginate to obtain PASP / SA corrosion inhibitor. Step 3: The hyperbranched polyamide-amine scale inhibitor, PASP / SA corrosion inhibitor, and sodium bentonite carrier are dispersed together in a cyclohexane solution containing ethyl cellulose, Span-80, and polydimethylsiloxane. The solvent phase separation is triggered by the dropwise addition of petroleum ether, which causes ethyl cellulose to precipitate and form a dense coating film on the surface of the composite particles, thereby obtaining a high-hardness water composite scale and corrosion inhibitor with a microencapsulated slow-release structure.

2. The preparation method of a high-hardness water composite scale and corrosion inhibitor according to claim 1, characterized in that, The specific preparation steps for the branched polyvinyliminocyanate are as follows: Maleic anhydride and N,N-dimethylformamide were added to a three-necked flask and stirred until evenly dispersed. A 50 wt% polyethyleneimine DMF mixed solution was added dropwise through a constant pressure dropping funnel. After the addition was complete, the reaction was stirred for 12-14 hours. Most of the DMF solvent was removed by rotary evaporator. The obtained product was washed with anhydrous ethanol, precipitated, and dried under vacuum to obtain branched polyethyleneimine ammonium acid.

3. The preparation method of a high-hardness water composite scale and corrosion inhibitor according to claim 2, characterized in that, The ratio of the mixed solution of maleic anhydride, N,N-dimethylformamide and polyethyleneimine DMF is 4.9-8.2g: 50-80mL: 16-20g.

4. The preparation method of a high-hardness water composite scale and corrosion inhibitor according to claim 1, characterized in that, The specific preparation steps of the hyperbranched polyamide-amine scale inhibitor are as follows: Deionized water, branched polyvinylimine acid, and sodium hydroxide were added to a three-necked flask equipped with a thermometer and a reflux condenser. The mixture was stirred at room temperature until clear, then ethylenediamine was added, and the mixture was stirred and refluxed at 80-90°C for 6-8 hours to carry out the polymerization reaction. After the reaction was completed, the mixture was rotary evaporated at 60-70°C, freeze-dried to constant weight, ground, and passed through a 200-mesh sieve to obtain the hyperbranched polyamide-amine scale inhibitor.

5. The preparation method of a high-hardness water composite scale and corrosion inhibitor according to claim 4, characterized in that, The ratio of deionized water, branched polyvinylimino acid, sodium hydroxide, and ethylenediamine is 80-100 mL: 5-8 g: 0.48-0.62 g: 0.36-0.48 g.

6. The preparation method of a high-hardness water composite scale and corrosion inhibitor according to claim 1, characterized in that, The specific preparation steps of the PASP / SA corrosion inhibitor are as follows: Polysuccinimide was added to deionized water and stirred until a suspension was formed. Then, sodium alginate and sodium hydroxide solution were slowly added and reacted at 60-70℃ for 4-6 hours. The pH was adjusted to neutral with hydrochloric acid, the product was precipitated with ethanol, filtered, washed, and vacuum dried to constant weight to obtain PASP / SA corrosion inhibitor.

7. The preparation method of a high-hardness water composite scale and corrosion inhibitor according to claim 6, characterized in that, The ratio of the amount of polysuccinimide, deionized water, sodium alginate and sodium hydroxide solution is 0.98-1.52g: 20-50mL: 0.5-0.8g: 6-8mL.

8. The preparation method of a high-hardness water composite scale and corrosion inhibitor according to claim 1, characterized in that, The specific preparation steps of the high-hardness water composite scale and corrosion inhibitor are as follows: Ethyl cellulose powder and cyclohexane were added to a flask, along with Span-80 and polydimethylsiloxane. The mixture was heated to 75-85°C and stirred until completely dissolved. Then, hyperbranched polyamide-amine scale inhibitor, PASP / SA corrosion inhibitor, and sodium bentonite were added. The mixture was stirred for 30-40 minutes and allowed to cool naturally to room temperature. Petroleum ether was slowly added dropwise through a constant pressure funnel. The mixture was then filtered. The filter cake was washed 2-4 times with petroleum ether and 2-4 times with distilled water. The cake was then dried at room temperature to obtain a high-hardness water composite scale and corrosion inhibitor.

9. The preparation method of a high-hardness water composite scale and corrosion inhibitor according to claim 8, characterized in that, The ratio of the following components is as follows: ethyl cellulose powder, cyclohexane, Span-80, polydimethylsiloxane, hyperbranched polyamide-amine scale inhibitor, PASP / SA corrosion inhibitor, sodium bentonite, and petroleum ether. The ratio is 2-3g: 70-100mL: 2-3g: 40-50mL: 1-2g: 1-2g: 2-3g: 70-100mL.

10. A high-hardness water composite scale and corrosion inhibitor, prepared according to any one of claims 1-9.

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