Rust removal and prevention cleaning fluid as well as use method and application thereof

Abstract

The invention relates to a rust removal and prevention cleaning solution as well as a use method and application thereof. The rust removal and prevention cleaning solution comprises an acid rust remover, a metal protective agent A, a metal protective agent B, an acid pickling neutralizer, a reducing agent and an anti-rust agent which are independently stored. When in use, the components are added into a cleaning loop of the fluorine pipeline of the air conditioner host step by step, the synergistic effect of the components is brought into full play, then the fluorine pipeline of the shell pass of the air conditioner host is effectively derusted, pipeline metal is not damaged, the re-rusting phenomenon can be effectively avoided after derusting, and the service life of the air conditioner host can be effectively prolonged.

Description

Technical Field

[0001] This invention belongs to the field of cleaning technology, specifically relating to a rust removal and rust prevention cleaning liquid, its usage method, and its application. Background Technology

[0002] The operation of an air conditioning unit's refrigerant system is based on the refrigerant's compression-condensation-throttling-evaporation cycle. Unlike traditional water systems, refrigerant systems achieve heat exchange directly through refrigerant phase change, offering advantages such as high efficiency, fast response, and compact piping structure. During operation, it is crucial to ensure accurate refrigerant charge and good piping sealing to prevent leaks that could degrade performance. However, in actual operation, various factors can lead to water ingress into the refrigerant piping, such as copper pipe corrosion or rupture, aging or damaged seals, unsealed pipe connections, and improper drainage system design causing condensate to backflow into the refrigerant piping.

[0003] The refrigerant circulation system involves multiple metals. The heat exchange surfaces are typically made of copper tubing, the circulation pipes are usually carbon steel, and the valves are typically cast iron. Water entering the refrigerant system can cause several problems, one of which is corrosion of metal components. This is because: firstly, water reacts with Freon to produce acidic substances such as hydrochloric acid and hydrogen fluoride, directly corroding carbon steel pipes, valves, and other metal components; secondly, as water enters the pipes, copper forms galvanic cells with carbon steel and cast iron in the electrolyte-containing water, causing preferential corrosion of carbon steel and iron. The dissolved iron ions further react with copper, causing copper corrosion. The copper ions produced after copper corrosion oxidize metallic iron, thus accelerating iron corrosion. Furthermore, uneven oxygen distribution within the pipes creates concentration cells, exacerbating pitting corrosion on the metal surface and forming honeycomb-like pores. Since the copper tubing used for heat exchange is usually relatively thin, pitting corrosion is more likely to cause perforation, leading to Freon leakage. Therefore, if water enters the refrigerant system, the water-containing refrigerant must be replaced promptly. However, before injecting new refrigerant, it is necessary to ensure that all components are undamaged and that the piping system is clean, dry, rust-free, and corrosion-free. Therefore, it is required to perform rust removal cleaning and rust prevention treatment on the piping.

[0004] Rust removal is typically carried out under acidic conditions, using acid to dissolve oxides on the metal surface. However, when using acid for rust removal, the acid can easily corrode the metal substrate, and the hydrogen produced during corrosion can also enter the metal, causing hydrogen embrittlement. Furthermore, once the metal oxides are dissolved, the active metal substrate of carbon steel and cast iron is exposed. During rinsing and draining the acidic rust removal solution, the active metal, in a humid environment, will quickly "rust again" upon contact with oxygen, causing secondary corrosion of metal components such as pipes and valves. Therefore, how to safely remove rust without damaging the metal and prevent "rust re-rusting" after rust removal has always been a challenge in the industry.

[0005] Therefore, developing a rust-removing and rust-preventing cleaning fluid that can safely remove rust without damaging metal and prevent "rust recurrence" after rust removal is one of the urgent technical problems to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a rust-removing and rust-preventing cleaning fluid, its usage method, and its application. This rust-removing and rust-preventing cleaning fluid can effectively remove rust from the refrigerant piping of the air conditioning unit without damaging the metal. Furthermore, it can prevent "re-rusting" after rust removal, thereby effectively extending the service life of the air conditioning unit.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a rust removal and rust prevention cleaning solution, wherein the rust removal and rust prevention cleaning solution comprises an acidic rust remover, a metal protectant A, a metal protectant B, an acid pickling neutralizer, a reducing agent and a rust inhibitor, each stored independently.

[0009] The acidic rust remover includes any one of the following components:

[0010] (a) The acidic rust remover comprises: acid, fluoride, surfactant and defoamer A; the acid comprises any one or a combination of at least two of hydrochloric acid, sulfuric acid, aminosulfonic acid, citric acid, methanesulfonic acid, phosphoric acid or oxalic acid;

[0011] (b) The acidic rust remover comprises: an acid, a surfactant and an antifoaming agent A; the acid includes hydrofluoric acid, and also includes any one or a combination of at least two of hydrochloric acid, sulfuric acid, aminosulfonic acid, citric acid, methanesulfonic acid, phosphoric acid or oxalic acid.

[0012] The metal protectant A includes metal corrosion inhibitor A.

[0013] The metal protectant B includes metal corrosion inhibitor B and alkali A.

[0014] The pickling neutralizing agent includes alkali B.

[0015] The reducing agent includes a metallic reducing agent.

[0016] The rust inhibitor includes: ethanolamine, organic carboxylic acid, chelating agent and defoamer B.

[0017] The refrigerant circulation system of an air conditioning unit involves various metals. Among them, the heat exchange surface is usually made of copper tubing, the circulation pipes are often made of carbon steel, and the valves are usually made of cast iron.

[0018] Based on the above facts, firstly, when the rust-removing and rust-preventing cleaning solution provided by this invention is used to clean the refrigerant piping of the air conditioning unit, the acidic rust remover will dissolve iron oxides into the cleaning solution, generating ferrous ions (Fe2+ and ferric ions). Ferric ions readily form stable complexes with fluoride ions in the solution: Fe... 3+ +6F - →[FeF6] 3- The complexation reaction reduces the concentration of free ferric ions in the solution. According to Le Chatelier's principle, the reaction equilibrium is driven to continue dissolving more rust to replenish the ferric ions. Simultaneously, the small atomic radius and high electronegativity of F- make it easy to penetrate the micropores of the rust layer, disrupting the dense structure of the oxide and accelerating overall peeling. Furthermore, because ferric ions have strong oxidizing properties, they can oxidize metallic copper, causing copper corrosion, i.e., 2Fe²⁺ → Fe³⁺. 3+ +Cu=2Fe 2+ +Cu 2+ Divalent copper ions are easily reduced by iron, causing iron corrosion, i.e., Cu. 2+ +Fe=Cu+Fe 2+ .

[0019] Secondly, the rust removal and rust prevention cleaning solution of the present invention includes metal protectant A and metal protectant B. Metal protectant A can adhere to the iron surface, which can slow down the corrosion of iron by hydrogen ions on the one hand, and slow down the corrosion of iron by copper ions on the other hand; metal protectant B can adhere to the copper surface, which can slow down the corrosion of copper by ferric ions.

[0020] In addition, after rust removal, the oxide layer or passivation film on the iron surface is removed, exposing a more active metal surface, which enhances the chemical activity of the iron. Therefore, it is necessary to promptly "deactivate" the acid-activated iron in the system, that is, the pickling neutralizing agent is needed to adjust the system to neutral or even slightly alkaline to reduce the continued corrosion of the exposed iron by the acid.

[0021] Furthermore, since corrosion is an oxidation process, after rust removal, active metals exposed to humid air and contacting oxygen in the air, or contacting oxygen in the rinsing water during rinsing, are prone to secondary corrosion, i.e., "re-rusting"; this type of corrosion is called electrochemical corrosion. Iron loses electrons at the anode and oxidizes to ferrous ions, while oxygen is reduced to hydroxide ions at the cathode, generating Fe(OH)2: 2Fe + O2 + 2H2O → 2Fe(OH)2. Fe(OH)2 is easily further oxidized to Fe(OH)3, and then further dehydrated to form rust (Fe2O3·xH2O). Using the metal reducing agent described in this invention can prevent iron from being oxidized during the rinsing process and during the discharge of the rinsing solution, thus avoiding "re-rusting".

[0022] Finally, after the above cleaning is completed, the refrigerant pipeline needs to be dried before refrigerant is refilled. This is usually done by blowing hot air. During the drying process, the hot and humid air comes into contact with the metal, which accelerates the oxidation reaction and can easily cause "rusting". Therefore, applying the rust inhibitor described in this invention to the pipeline before drying can prevent "rusting". In the rust inhibitor, the ethanolamine and organic carboxylic acid react to form an organic carboxylic acid ethanolamine salt with corrosion inhibition effect, which covers the metal surface and prevents the metal from contacting the external oxygen and other substances that are prone to corrosion, thereby delaying the occurrence of corrosion. The chelating agent can chelate calcium and magnesium ions in the water to prevent the formation of calcium carboxylate, magnesium carboxylate, etc., which reduce the corrosion inhibition effect.

[0023] In summary, by using the above components in combination, the resulting rust-removing and rust-preventing cleaning solution can effectively remove rust from the refrigerant piping of the air conditioner unit without damaging the metal. It can also prevent "rust recurrence" after rust removal, thereby effectively extending the service life of the air conditioner unit.

[0024] It should be noted that the acidic rust remover, metal protectant A, metal protectant B, pickling neutralizer, reducing agent and rust inhibitor contained in the rust removal and rust prevention cleaning liquid provided by the present invention need to be stored and used independently and do not need to be mixed together.

[0025] Preferably, by mass percentage, the acidic rust remover in (a) comprises: 10-98% acid, 0-10% fluoride, 0.1-5% surfactant, 0.1-0.5% defoamer A, and 0-80% water; the acid comprises any one or a combination of at least two of hydrochloric acid, sulfuric acid, aminosulfonic acid, citric acid, methanesulfonic acid, phosphoric acid, or oxalic acid.

[0026] Alternatively, by mass percentage, the acidic rust remover described in (b) comprises: 10-98% acid, 0.1-5% surfactant, 0.1-0.5% defoamer A, and 0-80% water; wherein the acid comprises 0.1-10% hydrofluoric acid, and further comprises any one or a combination of at least two of hydrochloric acid, sulfuric acid, aminosulfonic acid, citric acid, methanesulfonic acid, phosphoric acid, or oxalic acid.

[0027] Specific point values ​​for the 10-98% range can be selected from 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 98%, etc.; specific point values ​​for the 0-10% range can be selected from 0%, 2%, 4%, 6%, 8%, 10%, etc.; specific point values ​​for the 0.1-10% range can be selected from 0.1%, 2%, 4%, 6%, 8%, 10%, etc.; specific point values ​​for the 0.1-5% range can be selected from 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc.; and specific point values ​​for the 0-80% range can be selected from 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, etc.

[0028] The metal protectant A, by mass percentage, comprises: 10-100% metal corrosion inhibitor A and 0-90% water.

[0029] Among them, the specific point values ​​in the 10-100% range can be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, etc., and the specific point values ​​in the 0-90% range can be 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, etc.

[0030] The metal protectant B, by mass percentage, comprises: 5-100% metal corrosion inhibitor B, 0-20% alkali A, and 0-75% water.

[0031] Among them, the specific point values ​​for 5-100% can be 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, etc.; the specific point values ​​for 0-20% can be 0%, 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, etc.; and the specific point values ​​for 0-75% can be 0%, 5%, 10%, 15%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 75%, etc.

[0032] The pickling neutralizing agent comprises, by weight percentage: 20-100% alkali B and 0-80% water.

[0033] Among them, the specific point values ​​in the 20-100% range can be 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, etc., and the specific point values ​​in the 0-80% range can be 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, etc.

[0034] The reducing agent comprises, by mass percentage: 20-100% metal reducing agent and 0-80% water.

[0035] Among them, the specific point values ​​in the 20-100% range can be 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, etc., and the specific point values ​​in the 0-80% range can be 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, etc.

[0036] The rust inhibitor comprises, by weight percentage: 5-30% ethanolamine, 2-10% organic carboxylic acid, 1-10% chelating agent, 0-1% defoamer B, and 49-92% water.

[0037] Among them, specific point values ​​for 5-30% can be 5%, 10%, 15%, 20%, 25%, 30%, etc.; specific point values ​​for 2-10% can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, etc.; specific point values ​​for 1-10% can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.; specific point values ​​for 0-1% can be 0%, 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1%; and specific point values ​​for 49-92% can be 49%, 54%, 59%, 64%, 69%, 74%, 79%, 84%, 89%, 92%, etc.

[0038] Preferably, the fluoride mentioned in (a) includes any one or a combination of at least two of sodium fluoride, ammonium bifluoride, or hydrogen fluoride.

[0039] Preferably, the surfactant comprises any one or a combination of at least two of C8-C18 alkyl sulfonate, sodium α-olefin sulfonate, or C8-C18 fatty alcohol polyoxyethylene ether.

[0040] Preferably, the C8-C18 alkyl sulfonate includes any one or a combination of at least two of C8-C18 alkylbenzene sulfonate, C8-C18 alkylnaphthalene sulfonate, or C8-C18 diphenyl ether sulfonate.

[0041] Preferably, the defoamer A comprises any one or a combination of at least two of polydimethylsiloxane, polyether-modified polysiloxane, or fluorosiloxane.

[0042] Preferably, the metal corrosion inhibitor A comprises any one or a combination of at least two of the following: thiourea, o-xylenethiourea, thiols, C16-C22 alkyl quaternary ammonium salts, hexamethylenetetramine, cationic alkyl imidazoline, long-chain fatty amines, pyridine or its derivatives, aniline or its derivatives, quinoline or its derivatives, heterocyclic amines, cyclic imines, heterocyclic ketone amines, aniline-formaldehyde condensate, aniline-hexamethylenetetramine condensate, and alkynyl alcohols.

[0043] Preferably, the metal corrosion inhibitor A comprises a combination of thiourea, benzylquinoline quaternary ammonium chloride, hexadecylpyridine chloride, and hexamethylenetetramine.

[0044] The refrigerant circulation system of an air conditioning unit involves various metals, including copper, carbon steel, and iron. Due to the complex corrosion of metals, using a single corrosion inhibitor is often not effective enough.

[0045] Based on the characteristics of forming a protective film on the metal surface, corrosion inhibitors can be classified into oxide film type corrosion inhibitors, precipitation film type corrosion inhibitors, and adsorption type corrosion inhibitors. In acidic media, adsorption type corrosion inhibitors are usually used. According to different adsorption mechanisms, they can be further divided into physical adsorption and chemical adsorption.

[0046] This invention creatively discovers that thiourea (physical adsorption), benzylquinoline quaternary ammonium chloride (chemical adsorption), hexadecylpyridine chloride (chemical adsorption), and hexamethylenetetramine (primarily chemical adsorption, supplemented by physical adsorption) can all act as corrosion inhibitors. The combination of physical and chemical adsorption in a specific formulation allows the components to work together synergistically, resulting in better adhesion to the iron surface, slowing down the corrosion of iron by hydrogen and copper ions, and significantly improving the corrosion inhibition effect of the metal.

[0047] Preferably, the mass ratio of thiourea, benzylquinoline quaternary ammonium chloride, hexadecylpyridine chloride and hexamethylenetetramine is (1-5):(5-15):(2-10):(10-25).

[0048] Among them, the specific point values ​​of 1-5 can be 1, 2, 3, 4, 5, etc.; the specific point values ​​of 5-15 can be 5, 7, 9, 11, 13, 15, etc.; the specific point values ​​of 2-10 can be 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.; and the specific point values ​​of 10-25 can be 10, 13, 16, 19, 22, 25, etc.

[0049] Based on the synergistic effect of thiourea, benzylquinoline quaternary ammonium salt, hexadecylpyridine chloride and hexamethylenetetramine in corrosion inhibition, when the components are compounded according to the above formula, the components have a better synergistic effect.

[0050] Preferably, the metal corrosion inhibitor B comprises any one or a combination of at least two of benzotriazole, 2-mercaptobenzothiazole, aminobenzothiazole, methylbenzotriazole, 1-hydroxybenzotriazole, 4-hydroxybenzotriazole, 2-mercaptobenzoxazole, and 2-mercaptobenzimidazole.

[0051] Preferably, the metal corrosion inhibitor B comprises a combination of 2-mercaptobenzothiazole, 2-mercaptobenzoimidazolium, and methylbenzotriazole.

[0052] Different corrosion inhibitors have different adsorption rates under different conditions, and the thickness and uniformity of the adsorption film also vary.

[0053] This invention creatively discovers that 2-mercaptobenzothiazole, 2-mercaptobenzoimidazolium, and methylbenzotriazole can interact on the interfacial film to form a multilayered, dense adsorption film, which has a significant synergistic effect in reducing metal corrosion.

[0054] Preferably, the mass ratio of 2-mercaptobenzothiazole thiophene, 2-mercaptobenzoimidazolium and methylbenzotriazole is (1-5):(1-5):(5-25).

[0055] The specific point values ​​for 1-5 can be selected from 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, etc. The specific point values ​​for 5-25 can be selected from 5, 10, 15, 20, 25, etc.

[0056] Based on the synergistic effect of 2-mercaptobenzothiazole thiophene, 2-mercaptobenzoimidazolium and methylbenzotriazole in corrosion inhibition, when the components are compounded according to the above formula, the components have a better synergistic corrosion inhibition effect.

[0057] Preferably, the base A includes any one or a combination of at least two of sodium hydroxide, potassium hydroxide, or monoethanolamine.

[0058] Preferably, the alkali B comprises any one or a combination of at least two of sodium hydroxide, potassium hydroxide, monoethanolamine, diethanolamine, triethanolamine, or ammonia.

[0059] Preferably, the metal reducing agent includes any one or a combination of at least two of the following: carbazide, sodium hypophosphite, sodium sulfite, sodium bisulfite, sodium thiosulfate, or sodium metabisulfite.

[0060] Preferably, the ethanolamine includes any one or a combination of at least two of monoethanolamine, diethanolamine, or triethanolamine.

[0061] Preferably, the organic carboxylic acid includes any one or a combination of at least two of monocarboxylic acids or polycarboxylic acids having 8-22 carbon atoms, and more preferably any one or a combination of at least two of coconut oil acid, palm oil acid, ricinoleic acid, lauric acid, stearic acid, or sebacic acid.

[0062] Preferably, the chelating agent comprises any one or a combination of at least two of the following: ethylenediaminetetraacetic acid or its salt, nitroglycerin triacetic acid or its salt, citric acid or its salt, diethylenetriaminepentaacetic acid or its salt, hydroxyethylethylenediaminetriacetic acid or its salt, glutamic acid diacetic acid or its salt, propylenediaminetetraacetic acid or its salt, ethanol digluconic acid or its salt, and glucoheponic acid.

[0063] Preferably, the defoamer B comprises any one or a combination of at least two of polydimethylsiloxane, polyether-modified polysiloxane, or fluorosiloxane.

[0064] Secondly, the present invention provides an application of the rust-removing and rust-preventing cleaning fluid as described in the first aspect in cleaning the refrigerant pipeline of an air conditioning unit.

[0065] Thirdly, the present invention provides a method for using the rust-removing and rust-preventing cleaning solution as described in the first aspect to remove and prevent rust from the refrigerant piping of an air conditioning unit, the method comprising the following steps:

[0066] (1) Preparation: Connect the refrigerant pipe of the air conditioner unit and the bypass pipe to form a cleaning circuit, and hang the air conditioner unit refrigerant pipe cleaning reference in the bypass pipe.

[0067] (2) Rust removal process: Add cleaning water to the cleaning circuit and start the circulation; add acidic rust remover to the cleaning circuit and circulate for 15-30 minutes; then add metal protectant A and continue to circulate for 10-15 minutes; then add metal protectant B and circulate for 2-6 hours; observe that the rust on the air conditioning unit refrigerant pipeline cleaning reference in the side branch pipeline has been completely dissolved, and the rust removal process is completed.

[0068] (3) Neutralization process: Immediately after the rust removal process is completed, add pickling neutralizer to the cleaning circuit, circulate for 15-30 minutes, and then discharge the waste liquid.

[0069] (4) Reduction process: 5-15 minutes after the waste liquid is discharged in step (3), add cleaning water and reducing agent to the cleaning circuit; after the waste liquid is completely discharged, keep the reducing agent and cleaning water circulating in the cleaning circuit for 30-60 minutes, and then discharge the reduction waste liquid.

[0070] (5) Rust prevention process: After the reduction waste liquid is discharged in step (4) for 5-15 minutes, add cleaning water and rust inhibitor to the cleaning circuit; after the reduction waste liquid is completely discharged, keep the rust inhibitor and cleaning water circulating in the cleaning circuit for 1-3 hours, then discharge the rust prevention waste liquid and dry the pipeline to complete the cleaning of the pipeline.

[0071] Specific time points for the 15-30 min range can be selected as 15 min, 18 min, 21 min, 24 min, 27 min, 30 min, etc.; for the 10-15 min range, specific time points can be selected as 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, etc.; for the 2-6 h range, specific time points can be selected as 2 h, 3 h, 4 h, 5 h, 6 h, etc.; for the 5-15 min range, specific time points can be selected as 5 min, 7 min, 9 min, 11 min, 13 min, 15 min, etc.; for the 30-60 min range, specific time points can be selected as 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, etc.; and for the 1-3 h range, specific time points can be selected as 1 h, 1.5 h, 2 h, 2.5 h, 3 h, etc.

[0072] The air conditioner unit refrigerant pipeline cleaning reference used in step (1) is made of the same material and has a similar (or identical) degree of rust as the air conditioner unit refrigerant pipeline, and is used to determine the rust removal status of the air conditioner unit refrigerant pipeline. There is a transparent window in the side branch pipeline where the air conditioner unit refrigerant pipeline cleaning reference is suspended, allowing observation of the rust removal status of the air conditioner unit refrigerant pipeline cleaning reference.

[0073] Preferably, in step (2), when the acidic rust remover is solid, the acidic rust remover is dissolved before being added to the cleaning circuit to avoid excessive local acid concentration causing metal corrosion.

[0074] Preferably, the complete discharge of waste liquid in step (4) and the complete discharge of reduced waste liquid in step (5) means that the waste liquid has been completely discharged by calculating the total drainage volume, monitoring in real time and ensuring that the volume of waste liquid discharged reaches a preset threshold.

[0075] In the above rust removal process, metal protectant A, metal protectant B, and acidic rust remover are added step by step because metal protectant A and metal protectant B easily adsorb onto the metal surface to form a protective film, thereby preventing the acidic rust remover from corroding the metal substrate. However, metal protectant A and metal protectant B also adsorb onto the rust, slowing down the chemical reaction process of rust dissolution, thus significantly slowing down the rust removal process. Therefore, the acidic rust remover is added first, allowing the rust removal reaction to proceed rapidly. In areas where the rust layer is thin, the carbon steel metal substrate is exposed after the rust is removed. At this point, metal protectant A is added to protect the carbon steel metal substrate. When the concentration of ferric ions in the rust removal solution increases, the rust on the copper surface is removed, exposing the copper metal substrate. At this point, metal protectant B is added to form a dense protective film on the copper surface, protecting the copper metal substrate from corrosion.

[0076] During the reduction and rust prevention processes described above, a large amount of air enters the pipeline during the drainage of waste liquid. The moist metal comes into contact with a large amount of oxygen, increasing the risk of "re-rusting". Therefore, the "replenishing and draining at the same time" method is adopted, that is, after draining the waste liquid for 5-15 minutes, water is turned on to effectively avoid the occurrence of "re-rusting".

[0077] Preferably, in step (2) during the rust removal process, the mass ratio of the acidic rust remover to the cleaning water is (3-50):100, for example, it can be 3:100, 10:100, 15:100, 20:100, 25:100, 30:100, 35:100, 40:100, 45:100, 50:100, etc.

[0078] Preferably, in step (2) during the rust removal process, the mass ratio of the metal protective agent A to the cleaning water is (0.1-5):100, for example, it can be 0.1:100, 0.5:100, 1:100, 1.5:100, 2:100, 2.5:100, 3:100, 3.5:100, 4:100, 4.5:100, 5:100, etc.

[0079] Preferably, in step (2) during the rust removal process, the mass ratio of the metal protective agent B to the cleaning water is (0.1-5):100, for example, it can be 0.1:100, 0.5:100, 1:100, 1.5:100, 2:100, 2.5:100, 3:100, 3.5:100, 4:100, 4.5:100, 5:100, etc.

[0080] Preferably, in the neutralization process of step (3), the mass ratio of the pickling neutralizing agent to the cleaning water is (1-10):100, for example, it can be 1:100, 2:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, etc.

[0081] Preferably, in step (3), after adding the acid washing neutralizing agent, the pH value of the working solution in the cleaning circuit is 7.5-8.5, for example, it can be 7.5, 7.6, 7.7, 7.8, 7.9, 8, 8.1, 8.2, 8.3, 8.4, 8.5, etc.

[0082] Preferably, in step (4) during the reduction process, the mass ratio of the reducing agent to the cleaning water is (0.1-5):100, for example, it can be 0.1:100, 0.5:100, 1:100, 1.5:100, 2:100, 2.5:100, 3:100, 3.5:100, 4:100, 4.5:100, 5:100, etc.

[0083] Preferably, in step (5) during the rust prevention process, the mass ratio of the rust inhibitor to the cleaning water is (1-10):100, for example, it can be 1:100, 2:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, etc.

[0084] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0085] Compared with the prior art, the present invention has the following beneficial effects:

[0086] The rust removal and rust prevention cleaning solution provided by this invention includes an acidic rust remover, a protective agent A, a metal protective agent B, an acid pickling neutralizer, a reducing agent, and a rust inhibitor, each stored independently. When using these components, they need to be added step by step to the cleaning circuit of the refrigerant pipeline of the air conditioning unit to give full play to the synergistic effect of each component, thereby effectively removing rust from the refrigerant pipeline of the air conditioning unit without damaging the pipeline metal. It can also effectively prevent "rust return" after rust removal and effectively extend the service life of the air conditioning unit.

[0087] Furthermore, this invention creatively discovers that in metal protectant A, thiourea, benzylquinoline quaternary ammonium salt, hexadecylpyridine chloride, and hexamethylenetetramine simultaneously act as corrosion inhibitors. The physical and chemical adsorption of the specific formulation are combined and used in combination. The components work together to enhance each other's effectiveness, which can better adhere to the iron surface, slow down the corrosion of iron by hydrogen ions and copper ions, and significantly improve the corrosion inhibition effect of the metal.

[0088] Furthermore, in metal protectant B, 2-mercaptobenzothiazole, 2-mercaptobenzoimidazolium, and methylbenzotriazole can interact with each other on the interfacial film to form a multilayered, dense adsorption film, which has a significant synergistic effect in reducing metal corrosion.

[0089] Furthermore, the rust removal and rust prevention cleaning solution provided by the present invention, by sequentially adding acidic rust remover, metal protectant A, and metal protectant B during the rust removal and rust prevention process, can achieve more comprehensive protection of carbon steel base metal and copper base metal while ensuring the rust removal reaction speed. Attached Figure Description

[0090] Figure 1 This is a photograph of the rusted 20# carbon steel test piece from Test Example 1, which was not derusted.

[0091] Figure 2 This is a photograph of the 20# carbon steel test piece after 30 days of cleaning, as shown in Test Example 1.

[0092] Figure 3 This is a photograph of the refrigerant piping of the air conditioning unit that was not derusted in Test Example 2.

[0093] Figure 4 This is a photograph of the refrigerant piping of the air conditioner unit after 15 days of cleaning, as shown in Test Example 2. Detailed Implementation

[0094] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0095] Table 1 shows some of the raw material information involved in the following specific implementation methods.

[0096] Table 1

[0097]

[0098]

[0099] Example 1

[0100] A rust-removing and rust-preventing cleaning solution comprises, separately stored, an acidic rust remover, a metal protectant A, a metal protectant B, an acid pickling neutralizer, a reducing agent, and a rust inhibitor. The specific substances and amounts (mass percentage) contained in each of the above components are shown below:

[0101] Acidic rust remover: 50% citric acid monohydrate, 0.5% sodium α-olefin sulfonate, 5% sodium fluoride, 0.2% polyether-modified polysiloxane, and 44.3% water;

[0102] Metal Protectant A: Metal Corrosion Inhibitor A (thiourea, benzylquinoline quaternary ammonium chloride, hexadecylpyridine chloride and hexamethylenetetramine in a mass ratio of 3:10:7:20) 40%, water 60%;

[0103] Metal Protectant B: Metal Corrosion Inhibitor B (2-mercaptobenzothiazole, 2-mercaptobenzimidazole and methylbenzotriazole in a mass ratio of 1:1:5) 30%, potassium hydroxide 8%, water 62%;

[0104] Pickling neutralizing agent: 48% sodium hydroxide, 52% water;

[0105] Reducing agents: 95% sodium sulfite, 5% carbazide;

[0106] Rust inhibitor: 12.5% ​​monoethanolamine, 5% sebacic acid, 1% stearic acid, 0.2% polydimethylsiloxane, 2.5% tetrasodium ethylenediaminetetraacetate, and 78.8% water.

[0107] The preparation method of the acidic rust remover includes: first adding water to a clean stirring tank, then adding other components of the acidic rust remover while stirring, stirring until completely dissolved or completely mixed to obtain the acidic rust remover;

[0108] The preparation method of the metal protectant A includes: first adding water to a clean stirring vessel, then adding other components of the metal protectant A while stirring, and stirring until completely dissolved or completely mixed to obtain the metal protectant A;

[0109] The preparation method of the metal protectant B includes: first adding water to a clean stirring vessel, then adding other components of the metal protectant B while stirring, and stirring until completely dissolved or completely mixed to obtain the metal protectant B;

[0110] The preparation method of the pickling neutralizer includes: first adding water to a clean stirring tank, then adding other components of the pickling neutralizer while stirring, and stirring until completely dissolved or completely mixed to obtain the pickling neutralizer;

[0111] The method for preparing the reducing agent includes: thoroughly mixing all components in the reducing agent to obtain the reducing agent;

[0112] The method for preparing the rust inhibitor includes: first adding water to a clean mixing tank, then adding other components of the rust inhibitor while stirring, and stirring until completely dissolved or completely mixed to obtain the rust inhibitor.

[0113] Example 2

[0114] A rust-removing and rust-preventing cleaning solution comprises, separately stored, an acidic rust remover, a metal protectant A, a metal protectant B, an acid pickling neutralizer, a reducing agent, and a rust inhibitor. The specific substances and amounts (mass percentage) contained in each of the above components are shown below:

[0115] Acidic rust remover: 91.3% aminosulfonic acid, 0.5% sodium alkylbenzene sulfonate, 8% ammonium bifluoride, 0.2% polydimethylsiloxane;

[0116] Metal Protectant A: Metal Corrosion Inhibitor A (thiourea, benzylquinoline quaternary ammonium chloride, hexadecylpyridine chloride and hexamethylenetetramine in a mass ratio of 5:5:10:25) 35%, water 65%;

[0117] Metal Protectant B: Metal Corrosion Inhibitor B (2-mercaptobenzothiazole, 2-mercaptobenzimidazole and methylbenzotriazole in a mass ratio of 1:5:25) 25%, sodium hydroxide 15%, water 60%;

[0118] Pickling neutralizing agent: 46% sodium hydroxide, 54% water;

[0119] Reducing agent: 100% sodium sulfite;

[0120] Rust inhibitor: 13.0% monoethanolamine, 4.5% hydroxyethyl ethylenediamine triacetic acid, 6% lauric acid, 2% ricinoleic acid, 0.5% siloxane, 74% deionized water.

[0121] The preparation methods for the above components are consistent with those in Example 1.

[0122] Example 3

[0123] A rust-removing and rust-preventing cleaning solution comprises, separately stored, an acidic rust remover, a metal protectant A, a metal protectant B, an acid pickling neutralizer, a reducing agent, and a rust inhibitor. The specific substances and amounts (mass percentage) contained in each of the above components are shown below:

[0124] Acidic rust remover: 60% hydrochloric acid (36%), 5% hydrofluoric acid, 0.8% sodium dodecyl naphthalene sulfonate, 0.1% fluorosiloxane, 34.1% water;

[0125] Metal Protectant A: Metal Corrosion Inhibitor A (thiourea, benzylquinoline quaternary ammonium chloride, hexadecylpyridine chloride and hexamethylenetetramine in a mass ratio of 1:15:2:10) 28%, water 72%;

[0126] Metal Protectant B: Metal Corrosion Inhibitor B (2-mercaptobenzothiazole, 2-mercaptobenzimidazole and methylbenzotriazole in a mass ratio of 3:1:5) 44%, sodium hydroxide 16%, water 40%;

[0127] Pickling neutralizing agent: 30% potassium hydroxide, 10% monoethanolamine, 60% water;

[0128] Reducing agents: 50% sodium hypophosphite, 50% sodium metabisulfite;

[0129] Rust inhibitor: 20% diethanolamine, 5% sodium diethylenetriaminepentaacetate, 1% palmitoleic acid, 6% lauric acid, 0.5% polyether-modified polysiloxane, 67.5% deionized water.

[0130] The preparation methods for each of the above components are consistent with those in Example 1.

[0131] Example 4

[0132] This embodiment provides a rust-removing and rust-preventing cleaning solution, which differs from Example 1 only in that the total mass percentage of metal corrosion inhibitor A in metal protectant A remains unchanged at 40%, while metal corrosion inhibitor A is replaced with thiourea, benzylquinoline quaternary ammonium salt, and hexadecylpyridine chloride in a mass ratio of 3:10:7. The remaining formulation and preparation process of the rust-removing and rust-preventing cleaning solution are consistent with those of Example 1.

[0133] Example 5

[0134] This embodiment provides a rust-removing and rust-preventing cleaning solution, which differs from Example 1 only in that the total mass percentage of metal corrosion inhibitor A in metal protectant A remains unchanged at 40%, while metal corrosion inhibitor A is replaced with thiourea, benzylquinoline quaternary ammonium salt, and hexamethylenetetramine in a mass ratio of 3:10:20. The remaining formulation and preparation process of the rust-removing and rust-preventing cleaning solution are consistent with those of Example 1.

[0135] Example 6

[0136] This embodiment provides a rust-removing and rust-preventing cleaning solution, which differs from Example 1 only in that the total mass percentage of metal corrosion inhibitor A in metal protectant A remains unchanged at 40%, while metal corrosion inhibitor A is replaced with thiourea, hexadecylpyridine chloride, and hexamethylenetetramine in a mass ratio of 3:7:20. The remaining formulation and preparation process of the rust-removing and rust-preventing cleaning solution are consistent with those of Example 1.

[0137] Example 7

[0138] This embodiment provides a rust-removing and rust-preventing cleaning solution, which differs from Example 1 only in that the total mass percentage of metal corrosion inhibitor A in metal protectant A remains unchanged at 40%, while metal corrosion inhibitor A is replaced with benzylquinoline quaternary ammonium salt, hexadecylpyridine chloride, and hexamethylenetetramine in a mass ratio of 10:7:20. The remaining formulation and preparation process of the rust-removing and rust-preventing cleaning solution are consistent with those of Example 1.

[0139] Example 8

[0140] This embodiment provides a rust-removing and rust-preventing cleaning solution, which differs from Example 1 only in that the total mass percentage of metal corrosion inhibitor B in metal protectant B remains unchanged at 30%, and metal corrosion inhibitor B is replaced with 2-mercaptobenzothiazole and 2-mercaptobenzimidazole in a mass ratio of 1:1. The remaining formulation and preparation process of the rust-removing and rust-preventing cleaning solution are consistent with those of Example 1.

[0141] Example 9

[0142] This embodiment provides a rust-removing and rust-preventing cleaning solution, which differs from Example 1 only in that the total mass percentage of metal corrosion inhibitor B in the metal protectant B remains unchanged at 30%, and the metal corrosion inhibitor B is replaced with 2-mercaptobenzothiazole and methylbenzotriazole in a mass ratio of 1:5. The remaining formulation and preparation process of the rust-removing and rust-preventing cleaning solution are consistent with those of Example 1.

[0143] Example 10

[0144] This embodiment provides a rust-removing and rust-preventing cleaning solution, which differs from Example 1 only in that the total mass percentage of metal corrosion inhibitor B in metal protectant B remains unchanged at 30%, and metal corrosion inhibitor B is replaced with 2-mercaptobenzimidazole and methylbenzotriazole in a mass ratio of 1:5. The remaining formulation and preparation process of the rust-removing and rust-preventing cleaning solution are consistent with those of Example 1.

[0145] Comparative Example 1

[0146] This comparative example provides a rust-removing and rust-preventing cleaning solution, which differs from Example 1 only in that sodium fluoride is removed from the acidic rust remover, and the mass percentage of citric acid monohydrate is adjusted to 55%. The remaining formulation and preparation process of the rust-removing and rust-preventing cleaning solution are consistent with those of Example 1.

[0147] Application Example 1

[0148] This application example provides a method for removing and preventing rust on the refrigerant piping of a central air conditioning unit using a rust-removing and rust-preventing cleaning solution as described in Example 1.

[0149] (1) Preparation: Connect the refrigerant pipe of the air conditioning unit and the bypass pipe to form a cleaning circuit, and suspend a rusted 20# carbon steel test piece in the bypass pipe as a reference for cleaning the refrigerant pipe of the air conditioning unit (the 20# carbon steel test piece is similar in material and rust degree to the refrigerant pipe of the air conditioning unit, and is used to judge the rust removal status of the refrigerant pipe of the air conditioning unit).

[0150] (2) Rust removal process: Add cleaning water to the cleaning circuit and start the circulation; add acidic rust remover (8% of the mass of cleaning water) to the cleaning circuit and circulate for 20 minutes, then add metal protectant A (0.5% of the mass of cleaning water) and continue to circulate for 10 minutes, then add metal protectant B (0.3% of the mass of cleaning water) and circulate for 3.5 hours; observe that the rust on the 20# carbon steel test piece has been completely dissolved, and the rust removal process is completed.

[0151] (3) Neutralization process: Immediately after the rust removal process is completed, add pickling neutralizer to the cleaning circuit (the amount added is 3% of the mass of the cleaning water), adjust the pH value to 8.1, circulate for 20 minutes, and discharge the waste liquid.

[0152] (4) Reduction process: 10 minutes after the waste liquid is discharged in step (3), add cleaning water and reducing agent to the cleaning circuit (the amount added is 3% of the mass of the cleaning water); after the waste liquid is completely discharged, keep the reducing agent and cleaning water circulating in the cleaning circuit for 30 minutes, and then discharge the reduced waste liquid.

[0153] (5) Rust prevention process: 10 minutes after the reduction waste liquid is discharged in step (4), add cleaning water and rust inhibitor to the cleaning circuit (the amount added is 3% of the mass of the cleaning water); after the reduction waste liquid is completely discharged, keep the rust inhibitor and cleaning water circulating in the cleaning circuit for 2 hours, then discharge the rust prevention waste liquid and dry the pipeline to complete the cleaning of the pipeline.

[0154] Test Example 1

[0155] This test example conducts a laboratory rust prevention experiment on the rust removal and rust prevention cleaning solution of Example 1, simulating the rust removal and rust prevention method of Example 1. The specific process is as follows:

[0156] (1) Rust removal process: Prepare an 8% (by mass) acidic rust remover solution into a 500mL aqueous solution, pour it into a 600mL tall beaker, and suspend a rusted 20# carbon steel test piece as a reference for cleaning the refrigerant piping of the air conditioning unit (e.g., Figure 1 As shown in the image, the sample is suspended in the middle of the solution height, without contacting any side of the beaker. A magnetic stirring rotor (3cm long, 0.8mm in diameter) is placed in the beaker, and the beaker is placed on the magnetic stirrer. The stirring speed is set to 500 rpm, and stirring is started. After 20 minutes, metal protectant 1 is added (0.5% of the mass of the aqueous solution in the beaker). After stirring for another 10 minutes, metal protectant 2 is added (0.3% of the mass of the aqueous solution in the beaker), and stirring is continued for 3.5 hours. The rust on the 20# carbon steel sample is completely removed.

[0157] (2) Neutralization process: Immediately after the rust removal process, add pickling neutralizing agent to the beaker (the amount added is 3% of the mass of the aqueous solution in the beaker) and adjust the pH value to 8.1. Since there is no circulation system in the laboratory, the "replenishment and discharge" of the field application cannot be simulated. Therefore, 5 mL of waste liquid is added to the reduction process (to simulate the "replenishment and discharge" of the field), and the rest of the waste liquid is poured away.

[0158] (3) Reduction process: Prepare a 500mL aqueous solution of reducing agent at a mass percentage of 3%, pour it into the above beaker, suspend the test piece in the solution, and turn on the stirrer for 30min (stirrer and stirring speed are the same as in step (1)). Similarly, leave 5mL of waste liquid to be poured into the rust prevention process, and pour out the rest of the waste liquid.

[0159] (4) Rust prevention process: Prepare 500 mL of water solution with 3% mass of rust inhibitor and pour it into the above beaker. Suspend the test piece in the solution and turn on the stirrer for 2 hours (stirrer and stirring speed are the same as in step (1)). Then pour out the rust prevention waste liquid.

[0160] Remove the test piece and dry it with a hairdryer. Hang the test piece in the air and observe the rust-preventing effect.

[0161] The condition of the 20# carbon steel test piece before rust removal and rust prevention treatment is as follows: Figure 1 As shown, after rust removal and rust prevention treatment, and after being placed in an environment with a temperature of 15-27℃ and a humidity of 20-80% for 30 days, the condition of the 20# carbon steel test piece is as follows. Figure 2 As shown, the rust on the surface of the test piece has been removed, and no rust has reappeared after 30 days.

[0162] Test Example 2

[0163] This test case evaluates the field performance of the rust removal and rust prevention cleaning solution from Example 1. The rust removal and rust prevention method from Example 1 was used to clean the refrigerant piping of the central air conditioning unit. The piping condition before cleaning is as follows: Figure 3 As shown, the condition of the pipeline after cleaning and placement in an environment with a temperature of 15-27℃ and a humidity of 20-80% for 15 days is as follows. Figure 4 As shown, the rust on the pipeline has been removed, and no rust has reappeared after 15 days.

[0164] Test Example 3

[0165] Comparative test of rust removal and rust prevention performance.

[0166] (1) Test objects: Rust removal and rust prevention cleaning solutions of each embodiment and comparative example.

[0167] (2) Test method:

[0168] (2.1) Rust removal performance: Mix the acidic rust remover and water in a 150mL beaker to prepare a rust removal working solution with a mass percentage of 8% in 100mL. Add 5g of ferric oxide powder (800 mesh) to each 100mL working solution and place it in a stirring rotor (Type B, 25mm long, 0.7mm in diameter). Keep the working solution temperature at 25℃±2℃, turn on the stirrer, and stir at 200rpm for 4 hours. After stirring, filter the working solution and take the clear liquid to determine the total iron ion content. The higher the total iron ion content, the better the rust removal performance of the rust remover.

[0169] The acidic rust remover in the rust removal and rust prevention cleaning solutions provided in Examples 1-3 and Comparative Example 1 was tested according to the above test methods. The test results are shown in Table 2.

[0170] Table 2

[0171] Sample to be tested Iron ion concentration (ppm) Example 1 285.6 Example 2 278.0 Example 3 275.2 Comparative Example 1 78.8

[0172] As can be seen from the data in Table 2, the acidic rust remover in the rust removal and rust prevention cleaning solution provided in Examples 1-3 has excellent rust removal performance. Furthermore, based on the comparison of the data in Example 1 and Comparative Example 1, it can be seen that the rust removal effect will be greatly reduced if fluoride is not added to the acidic rust remover.

[0173] (2.2) Corrosion inhibition performance: The metal protectant A and metal protectant B in the rust removal and rust prevention cleaning solutions of Examples 1-10 were tested according to the evaluation index and experimental method of chemical cleaning corrosion inhibitor application in DL / T 523. The temperature and concentration parameters were adjusted according to the field application conditions.

[0174] The test conditions for metal protectant A are as follows: concentration of acidic rust remover: 8%; concentration of metal protectant A: 0.5%; temperature: 30℃±2℃; test time: 4h; metal material: 20# steel.

[0175] The test conditions for metal protectant B are as follows: concentration of acidic rust remover: 8%; concentration of metal protectant A: 0.5%; concentration of metal protectant B: 0.3%; temperature: 30℃±2℃; test time: 4h; metal material: copper T-2, 20# steel.

[0176] The corrosion effect test results of metal protectant A and metal protectant B in Examples 1-10 are shown in Tables 3 and 4, respectively:

[0177] Table 3

[0178]

[0179] Table 4

[0180]

[0181]

[0182] As can be seen from the data in Tables 3 and 4, both metal protectant A and metal protectant B in the rust removal and rust prevention cleaning solution of the present invention have excellent corrosion inhibition properties.

[0183] A comparison of the data from Examples 1 and 4-7 shows that thiourea, benzylquinoline quaternary ammonium salt, hexadecylpyridine chloride, and hexamethylenetetramine have a significant synergistic effect in improving corrosion inhibition performance.

[0184] A comparison of the data from Examples 1 and 8-10 shows that 2-mercaptobenzothiazide, 2-mercaptobenzimidazole and methylbenzotriazole can interact with each other on the interfacial film to form a multilayered, dense adsorption film, which has a significant synergistic effect in reducing metal corrosion.

[0185] (2.3) Comparative experiment on the rust removal effect of adding metal protectant and acidic rust remover simultaneously versus adding them in batches during the rust removal process:

[0186] Test method: The acidic rust remover, metal protectant A and metal protectant B from Example 1 were used for testing. In a 150mL beaker, two 100mL portions of rust-removing working solution were prepared by mixing an acidic rust remover with water at an 8% mass percentage, labeled as 1# and 2#. Metal protectant A (0.5% mass percentage) and metal protectant B (0.3% mass percentage) were added to rust-removing working solution 2#. 5g of ferric oxide powder (800 mesh) was added to each working solution, and a stirring rotor (Type B, 25mm long, 0.7mm diameter) was placed inside. The working solution temperature was maintained at 25℃±2℃, and stirring was started at 200rpm for 30 minutes. Then, 0.5% metal protectant A was added to working solution 1#, and stirring continued for 15 minutes. Finally, 0.3% metal protectant B was added to working solution 1#. The total stirring time was 4 hours. After the reaction was complete, both working solutions were filtered, and the total iron ion content of the clear liquid was determined. The test results are shown in Table 5.

[0187] Table 5

[0188] Test sample Total iron ion content (ppm) 1# Rust Removal Fluid 236.5 2# Rust Removal Fluid 178.2

[0189] As can be seen from the data in Table 5, adding acidic rust remover, metal protectant A, and metal protectant B in batches can improve the rust removal and anti-rust cleaning solution's rust removal effect.

[0190] The applicant declares that the technical solution of this invention is illustrated by the above embodiments, but this invention is not limited to the above embodiments, that is, it does not mean that this invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the products of this invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.

[0191] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0192] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

Claims

1. A rust-removing and rust-preventing cleaning solution, characterized in that, The rust removal and rust prevention cleaning solution includes, separately stored, an acidic rust remover, a metal protectant A, a metal protectant B, an acid pickling neutralizer, a reducing agent, and a rust inhibitor; The acidic rust remover includes any one of the following components: (a) The acidic rust remover comprises: acid, fluoride, surfactant and defoamer A; the acid comprises any one or a combination of at least two of hydrochloric acid, sulfuric acid, aminosulfonic acid, citric acid, methanesulfonic acid, phosphoric acid or oxalic acid; (b) The acidic rust remover comprises: an acid, a surfactant, and an antifoaming agent A; the acid includes hydrofluoric acid, and also includes any one or a combination of at least two of hydrochloric acid, sulfuric acid, aminosulfonic acid, citric acid, methanesulfonic acid, phosphoric acid, or oxalic acid; The metal protective agent A includes a metal corrosion inhibitor A; The metal protective agent B includes metal corrosion inhibitor B and alkali A; The pickling neutralizer includes base B; The reducing agent includes a metal reducing agent; The rust inhibitor includes: ethanolamine, organic carboxylic acid, chelating agent and defoamer B.

2. The rust-removing and rust-preventing cleaning solution according to claim 1, characterized in that, The acidic rust remover described in (a) comprises, by weight percentage: 10-98% acid, 0.1-10% fluoride, 0.1-5% surfactant, 0.1-0.5% defoamer A, and 0-80% water; the acid comprises any one or a combination of at least two of hydrochloric acid, sulfuric acid, aminosulfonic acid, citric acid, methanesulfonic acid, phosphoric acid, or oxalic acid. Alternatively, by mass percentage, the acidic rust remover described in (b) comprises: 10-98% acid, 0.1-5% surfactant, 0.1-0.5% defoamer A, and 0-80% water; the acid comprises 0.1-10% hydrofluoric acid, and further comprises any one or a combination of at least two of hydrochloric acid, sulfuric acid, aminosulfonic acid, citric acid, methanesulfonic acid, phosphoric acid, or oxalic acid; The metal protective agent A, by mass percentage, comprises: 10-100% metal corrosion inhibitor A and 0-90% water; The metal protectant B, by mass percentage, comprises: 5-100% metal corrosion inhibitor B, 0-20% alkali A, and 0-75% water; The pickling neutralizing agent comprises, by weight percentage: alkali B 20-100% and water 0-80%; The reducing agent comprises, by mass percentage: 20-100% metal reducing agent and 0-80% water; The rust inhibitor comprises, by weight percentage: 5-30% ethanolamine, 2-10% organic carboxylic acid, 1-10% chelating agent, 0-1% defoamer B, and 49-92% water.

3. The rust-removing and rust-preventing cleaning solution according to claim 1 or 2, characterized in that, The fluoride mentioned in (a) includes any one or a combination of at least two of sodium fluoride, ammonium bifluoride, or hydrogen fluoride; Preferably, the surfactant comprises any one or a combination of at least two of C8-C18 alkyl sulfonate, sodium α-olefin sulfonate, or C8-C18 fatty alcohol polyoxyethylene ether. Preferably, the C8-C18 alkyl sulfonate includes any one or a combination of at least two of C8-C18 alkylbenzene sulfonate, C8-C18 alkylnaphthalene sulfonate, or C8-C18 diphenyl ether sulfonate; Preferably, the defoamer A comprises any one or a combination of at least two of polydimethylsiloxane, polyether-modified polysiloxane, or fluorosiloxane.

4. The rust-removing and rust-preventing cleaning solution according to any one of claims 1-3, characterized in that, The metal corrosion inhibitor A comprises any one or a combination of at least two of the following: thiourea, o-xylenethiourea, thiols, C16-C22 alkyl quaternary ammonium salts, hexamethylenetetramine, cationic alkyl imidazoline, long-chain fatty amines, pyridine or its derivatives, aniline or its derivatives, quinoline or its derivatives, heterocyclic amines, cyclic imines, heterocyclic ketone amines, aniline-formaldehyde condensate, aniline-hexamethylenetetramine condensate, and alkynyl alcohols. Preferably, the metal corrosion inhibitor A comprises a combination of thiourea, benzylquinoline quaternary ammonium chloride, hexadecylpyridine chloride, and hexamethylenetetramine; Preferably, the mass ratio of thiourea, benzylquinoline quaternary ammonium chloride, hexadecylpyridine chloride and hexamethylenetetramine is (1-5):(5-15):(2-10):(10-25).

5. The rust-removing and rust-preventing cleaning solution according to any one of claims 1-4, characterized in that, The metal corrosion inhibitor B comprises any one or a combination of at least two of benzotriazole, 2-mercaptobenzothiazole, aminobenzothiazole, methylbenzotriazole, 1-hydroxybenzotriazole, 4-hydroxybenzotriazole, 2-mercaptobenzoxazole, and 2-mercaptobenzimidazole. Preferably, the metal corrosion inhibitor B comprises a combination of 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, and methylbenzotriazole; Preferably, the mass ratio of 2-mercaptobenzothiazole thiophene, 2-mercaptobenzoimidazolium and methylbenzotriazole is (1-5):(1-5):(5-25); Preferably, the base A includes any one or a combination of at least two of sodium hydroxide, potassium hydroxide, or monoethanolamine.

6. The rust-removing and rust-preventing cleaning solution according to any one of claims 1-5, characterized in that, The alkali B includes any one or a combination of at least two of sodium hydroxide, potassium hydroxide, monoethanolamine, diethanolamine, triethanolamine, or ammonia. Preferably, the metal reducing agent includes any one or a combination of at least two of the following: carbazide, sodium hypophosphite, sodium sulfite, sodium bisulfite, sodium thiosulfate, or sodium metabisulfite. Preferably, the ethanolamine includes any one or a combination of at least two of monoethanolamine, diethanolamine, or triethanolamine; Preferably, the organic carboxylic acid includes any one or a combination of at least two of monocarboxylic acids or polycarboxylic acids having 8-22 carbon atoms, and more preferably any one or a combination of at least two of coconut oil acid, palm oil acid, ricinoleic acid, lauric acid, stearic acid or sebacic acid; Preferably, the chelating agent comprises any one or a combination of at least two of the following: ethylenediaminetetraacetic acid or its salt, nitroglycerin triacetic acid or its salt, citric acid or its salt, diethylenetriaminepentaacetic acid or its salt, hydroxyethylethylenediaminetriacetic acid or its salt, glutamic acid diacetic acid or its salt, propylenediaminetetraacetic acid or its salt, ethanol digluconic acid or its salt, and glucoheponic acid. Preferably, the defoamer B comprises any one or a combination of at least two of polydimethylsiloxane, polyether-modified polysiloxane, or fluorosiloxane.

7. The application of a rust-removing and rust-preventing cleaning solution as described in any one of claims 1-6 in cleaning the refrigerant piping of an air conditioning unit.

8. A method for removing and preventing rust on the refrigerant piping of an air conditioning unit using a rust-removing and rust-preventing cleaning solution as described in any one of claims 1-6, characterized in that, The method includes the following steps: (1) Preparation: Connect the refrigerant pipe of the air conditioning unit and the bypass pipe to form a cleaning circuit, and hang the air conditioning unit refrigerant pipe cleaning reference in the bypass pipe. (2) Rust removal process: Add cleaning water to the cleaning circuit and start the circulation; add acidic rust remover to the cleaning circuit and circulate for 15-30 minutes; then add metal protectant A and continue to circulate for 10-15 minutes; then add metal protectant B and circulate for 2-6 hours; observe that the rust on the air conditioning unit refrigerant pipeline cleaning reference in the side branch pipeline has been completely dissolved, and the rust removal process is completed. (3) Neutralization process: Immediately after the rust removal process is completed, add pickling neutralizer to the cleaning circuit, circulate for 15-30 minutes, and then discharge the waste liquid; (4) Reduction process: 5-15 minutes after the waste liquid is discharged in step (3), add cleaning water and reducing agent to the cleaning circuit; after the waste liquid is completely discharged, keep the reducing agent and cleaning water circulating in the cleaning circuit for 30-60 minutes, and then discharge the reduction waste liquid. (5) Rust prevention process: After the reduction waste liquid is discharged in step (4) for 5-15 minutes, add cleaning water and rust inhibitor to the cleaning circuit; after the reduction waste liquid is completely discharged, keep the rust inhibitor and cleaning water circulating in the cleaning circuit for 1-3 hours, then discharge the rust prevention waste liquid and dry the pipeline to complete the cleaning of the pipeline.

9. The method according to claim 8, characterized in that, In step (2) during the rust removal process, the mass ratio of the acidic rust remover to the cleaning water is (3-50):100; Preferably, in step (2) during the rust removal process, the mass ratio of the metal protective agent A to the cleaning water is (0.1-5):100; Preferably, in step (2) during the rust removal process, the mass ratio of the metal protectant B to the cleaning water is (0.1-5):

100.

10. The method according to claim 8 or 9, characterized in that, In step (3) during the neutralization process, the mass ratio of the pickling neutralizing agent to the cleaning water is (1-10):100; Preferably, in step (3), after adding the acid washing neutralizing agent, the pH value of the working solution in the cleaning circuit is 7.5-8.5; Preferably, in step (4) during the reduction process, the mass ratio of the reducing agent to the cleaning water is (0.1-5):100; Preferably, in step (5) during the rust prevention process, the mass ratio of the rust inhibitor to the cleaning water is (1-10):100.

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