Metal corrosion inhibitor, preparation method thereof, pickling reagent and application of pickling reagent

Abstract

The invention provides a metal corrosion inhibitor, a preparation method of the metal corrosion inhibitor, a pickling reagent and application of the pickling reagent, the metal corrosion inhibitor is applied to metal corrosion inhibition, and the structure of the metal corrosion inhibitor is as shown in a formula I: # imgabs0 #, r1 is one of an alkyl group of C1 to C16, an alkylene group of C2 to C16, a cyclic group of C5 to C16, an aryl group of C6 to C16, an alkyl group of C1 to C16 carrying a substituent group, an alkylene group of C2 to C16 carrying a substituent group, a cyclic group of C5 to C16 carrying a substituent group and an aryl group of C6 to C16 carrying a substituent group; and the metal corrosion problem is effectively relieved, the effect is remarkable, and the method is worthy of popularization.

Description

Technical Field

[0001] The invention belongs to the field of metal pickling, and in particular relates to a metal corrosion inhibitor, a pickling agent and applications thereof. Background Art

[0002] For metal materials, metal corrosion is one of the great threats that limit their long-term use. It will not only affect the benefits of industrial production, but also the corrosion products and engineering waste will threaten human health and life to a certain extent. For example, metal pickling process is a widely used metal surface cleaning process, which can effectively dissolve and remove dirt, grease, oxide layer and other pollutants on the metal surface, significantly improving the appearance and texture of the metal. Commonly used pickling agents such as hydrochloric acid are often used as industrial cleaning agents in pickling processes, petrochemical production and oil well practice because of the slow dissolution rate of hydrochloric acid for base metals such as steel. However, hydrochloric acid is volatile and poses a great threat to environmental pollution. In addition, metals in hydrochloric acid solutions will also suffer from surface rust, cracking, local pitting and perforation.

[0003] Therefore, it is urgent to propose a metal corrosion inhibitor, a pickling agent and applications thereof to control or slow down the corrosion problem of metals in the pickling agent. Summary of the invention

[0004] In order to solve the technical problem of metal corrosion in pickling reagents in the above-mentioned common technologies, the present invention provides a metal corrosion inhibitor, which is used as a metal corrosion inhibitor for metal corrosion inhibition. The structure of the metal corrosion inhibitor is shown in Formula I:

[0005]

[0006] Among them, R 1 C1~C 16 Alkyl, C2~C 16 Olefin groups, C5~C 16 The ring group, C6~C 16 aromatic groups, C1~C 16 Alkyl, C2~C 16 Olefin groups, C5~C 16 The ring group and the C6~C 16 One of the aromatic groups;

[0007] R 2 C1~C 16 Alkyl, alkylaryl, C1~C 16 One of an alkyl group and an alkylaryl group having a substituent.

[0008] The substituent includes at least one of a C1-C6 alkyl group, a C1-C6 alkoxy group, a C1-C6 alkylthio group, and a hydroxyl group.

[0009] Furthermore, R 1 Including one of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, pentyl, isopentyl, sec-pentyl, neopentyl, n-hexyl, isohexyl, sec-hexyl, n-heptyl, isoheptyl, n-octyl, isooctyl, n-nonyl, undecyl, pentadecyl, ethoxyethyl, tert-butoxyethyl, phenyl, benzyl, phenethyl, styryl, m-methylphenyl, p-ethylphenyl, p-methoxyphenyl, cyclopropyl, cyclopentyl, cyclohexyl, propenyl or propynyl.

[0010] Furthermore, R 1 is one of n-octyl, isooctyl, undecyl, phenyl or benzyl; R 2 It is one of methyl, ethyl, n-propyl, n-butyl, isobutyl, n-hexyl, phenyl and benzyl.

[0011] Furthermore, the R 1 Including phenyl, the R 2 Includes one of ethyl, n-propyl and n-butyl.

[0012] The present invention provides a method for preparing the metal corrosion inhibitor as described above, comprising the steps of: mixing a solubilizer, NaSCN, dichloromethane and benzoyl chloride, and heating to 20 to 30° C. for reaction for 3 to 4 hours to obtain a pretreatment agent;

[0013] Adding an alcohol compound to the pretreatment agent, heating to 30-40° C. for reaction for 3-5 hours, and then filtering to remove salt and solvent in sequence to obtain the metal corrosion inhibitor; the alcohol compound includes one of ethanol, n-propanol, and n-butanol;

[0014] The molar ratio of the benzoyl chloride, the NaSCN, and the alcohol compound is 1:0.95-1.25:1.0-2.0; the amount of the dichloromethane is 20-50 mL / 0.1 mol of the benzoyl chloride; and the amount of the solubilizer is 0.1-1 g / 0.1 mol of the benzoyl chloride.

[0015] The present invention provides a pickling reagent, which comprises a pickling medium and a metal corrosion inhibitor as described above, wherein the concentration of the metal corrosion inhibitor in the pickling reagent is 10 to 200 mg / L, the concentration of the pickling medium in the pickling reagent is 0.5 to 2 mol / L, and the type of the pickling medium comprises hydrochloric acid or sulfuric acid.

[0016] Furthermore, the pickling reagent also includes a polyethylene glycol series solubilizer, and the concentration of the solubilizer is 0.01 to 0.5 mg / L.

[0017] The present invention provides an application of the pickling reagent as described in any one of the above in pickling of metal materials, comprising the steps of: mixing the metal corrosion inhibitor with the pickling medium to prepare the pickling reagent;

[0018] The pickling agent is used to carry out pickling treatment on the metal material, the pickling treatment lasts for 10 to 96 hours, and the pickling treatment temperature is 10 to 35°C.

[0019] Furthermore, the metal material includes carbon steel.

[0020] Furthermore, the step of using the pickling agent to pickle the metal material includes: immersing the metal material that has been subjected to grinding, degreasing and drying treatments in sequence in the pickling agent.

[0021] Compared with the prior art, the present invention has at least the following advantages:

[0022] The present invention provides a metal corrosion inhibitor. Thanks to the conjugation effect between C=O and C=S in the molecule, the two groups can react with the same metal ion and form a six-membered ring structure, thereby enhancing the chelating ability of the corrosion inhibitor molecule to the metal on the surface of the metal material. In addition, based on the synergy within the -CO-N-CS-S molecule, the combined control of R1 and R2 at the end is further coordinated to help form a hydrophobic film on the surface of the metal material and optimize the corrosion inhibition effect.

[0023] The metal corrosion inhibitor in the present invention can be compounded with a pickling medium (such as hydrochloric acid, sulfuric acid) as a pickling reagent for use, which can significantly improve the corrosion inhibition performance of the pickling reagent for metal materials while ensuring the pickling effect, and increase the corrosion inhibition efficiency of the metal material after pickling treatment to more than 90%. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0025] Figure 1 is the H NMR spectrum of N-benzoyl-O-ethylthiocarbamate prepared in the embodiment of the present invention;

[0026] Figure 2This is the H NMR spectrum of N-benzoyl-O-n-propylthiocarbamate in Example 2 of the present invention;

[0027] Figure 3 This is the H NMR spectrum of N-benzoyl-O-n-butylthiocarbamate prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0030] When numerical ranges are given in the embodiments, it should be understood that unless otherwise specified in the present invention, both endpoints of each numerical range and any value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention are familiar to those skilled in the art and the description of the present invention, and any method, device and material of the prior art similar or equivalent to the method, device and material in the embodiments of the present invention can also be used to implement the present invention.

[0031] Metal corrosion inhibitors can form a strong protective film on the metal surface, effectively preventing the corrosion reaction from occurring.

[0032] Metal pickling is a widely used metal surface cleaning process that can effectively dissolve and remove dirt, grease, oxide layers and other contaminants on the metal surface, significantly improving the appearance and texture of the metal. However, due to the acidity of the pickling agent, chemical corrosion and electrochemical corrosion often occur on the metal surface.

[0033] Chemical corrosion: When the metal surface comes into contact with an acidic solution, the metal undergoes a replacement reaction with the hydrogen ions in the acid to generate metal ions and hydrogen, causing the metal surface to be corroded.

[0034] Electrochemical corrosion: Acidic solution is an electrolyte solution. When metal is immersed in it, different parts of the metal surface may form a primary battery due to the potential difference, leading to the occurrence of electrochemical corrosion. In addition, if there are impurities or defects on the metal surface, it may also become a catalytic point for electrochemical corrosion.

[0035] At this time, the use of corrosion inhibitors in the pickling reagent is critical to the corrosion inhibition of metals.

[0036] In order to solve the technical problems faced in the conventional technologies, the present invention provides a metal corrosion inhibitor, the structure of which is shown in Formula I:

[0037]

[0038] Among them, R 1 C1~C 16 Alkyl, C2~C 16 Olefin groups, C5~C 16 The ring group or C6~C 16 One of the aryl groups, the R 1 Including the C1~C 16 The alkyl group of C2~C 16 The olefin group, the C5~C 16 The ring group or the C6~C 16 The aromatic group;

[0039] R 2 C1~C 16 An alkyl or alkylaryl group.

[0040] Thanks to the conjugation effect between C=O and C=S in the molecule, the two groups can react with the same metal ion and form a six-membered ring structure, thereby strengthening the chelating ability of the corrosion inhibitor molecule to the metal on the surface of the metal material. In addition, based on the synergy within the -CO-N-CS-S molecule, the joint control of R1 and R2 at the end further helps to form a hydrophobic film on the surface of the metal material and optimize the corrosion inhibition effect.

[0041] The above-mentioned metal corrosion inhibitor can also be compounded with pickling media (such as hydrochloric acid and sulfuric acid) as pickling reagents, which can significantly improve the corrosion inhibition performance of the pickling reagents for metal materials while ensuring the pickling effect, and increase the corrosion inhibition efficiency of the metal materials after pickling treatment to more than 90%.

[0042] In some embodiments, the substituent includes at least one of a C1-C6 alkyl group, a C1-C6 alkoxy group, a C1-C6 alkylthio group, and a hydroxyl group.

[0043] For example, R 1It may include one of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, pentyl, isopentyl, sec-pentyl, neopentyl, n-hexyl, isohexyl, sec-hexyl, n-heptyl, isoheptyl, n-octyl, isooctyl, n-nonyl, undecyl, pentadecyl, ethoxyethyl, tert-butoxyethyl, phenyl, benzyl, phenethyl, styryl, m-methylphenyl, p-ethylphenyl, p-methoxyphenyl, cyclopropyl, cyclopentyl, cyclohexyl, propenyl or propynyl.

[0044] Another exemplary method, R 1 Including phenyl.

[0045] For example, R 2 It may be methyl, ethyl, n-propyl, n-butyl, isobutyl, n-hexyl, phenyl or benzyl.

[0046] Another exemplary method, R 2 Includes one of ethyl, n-propyl and n-butyl.

[0047] In some embodiments, the metal corrosion inhibitor includes one of N-benzoyl-O-ethylthiocarbamate, N-benzoyl-O-n-propylthiocarbamate, or N-benzoyl-O-n-butylthiocarbamate.

[0048] The present invention provides a method for preparing a metal corrosion inhibitor as described in any one of the above, comprising the steps of: mixing a solubilizer, NaSCN, dichloromethane, and benzoyl chloride, and heating the mixture to 20 to 30° C. for reaction for 3 to 4 hours to obtain a pretreatment agent;

[0049] Adding an alcohol compound to the pretreatment agent, heating to 30-40° C. for reaction for 3-5 hours, and then filtering to remove salt and solvent in sequence to obtain the metal corrosion inhibitor; the alcohol compound includes one of ethanol, n-propanol, and n-butanol;

[0050] Exemplarily, the solubilizer, NaSCN, dichloromethane, and benzoyl chloride can be mixed, and the temperature can be raised to 25° C. to react for 3.5 hours to obtain a pretreatment agent; an alcohol compound can be added to the pretreatment agent, and the temperature can be raised to 35° C. to react for 4 hours, and then the pretreatment agent can be filtered to remove salt and the dichloromethane can be recovered by rotary evaporation to obtain the metal corrosion inhibitor.

[0051] The synthesis steps are shown in Formula II; the alcohol compound includes one of ethanol, n-propanol and n-butanol;

[0052]

[0053] Wherein, the molar ratio of the benzoyl chloride, the NaSCN, and the alcohol compound is 1:0.95-1.25:1.0-2.0;

[0054] The amount of dichloromethane used is 20-50 mL / 0.1 mol benzoyl chloride;

[0055] The dosage of the solubilizer is 0.1-1 g / 0.1 mol benzoyl chloride.

[0056] Exemplarily, the solubilizing agent includes PEG-400.

[0057] As another example, the alcohol compound may be one of ethanol, n-propanol, and n-butanol.

[0058] In the case where the alcohol compound is ethanol, the chemical name of the metal corrosion inhibitor is N-benzoyl-O-ethylthiocarbamate

[0059] In the case where the alcohol compound is n-propanol, the chemical name of the metal corrosion inhibitor is N-benzoyl-O-n-propylthiocarbamate.

[0060] In the case where the alcohol compound is n-butanol, the chemical name of the metal corrosion inhibitor is N-benzoyl-O-n-butylthiocarbamate

[0061] It should be noted that, based on the excellent metal ion chelating effect and hydrophobic effect of the above-mentioned metal corrosion inhibitor, it can be used alone for metal corrosion inhibition in the metallurgical industry, petrochemical industry, automobile manufacturing industry and aerospace field to improve the service life of metal materials.

[0062] The above metal corrosion inhibitor can also be compounded with a pickling medium to form a pickling reagent for use in metal pickling treatment.

[0063] In some embodiments, the concentration of the metal corrosion inhibitor in the pickling reagent may be 10-200 mg / L, and the concentration of the pickling medium in the pickling reagent may be 0.5-2 mol / L. The type of the pickling medium may include hydrochloric acid or sulfuric acid.

[0064] In other embodiments, the pickling reagent may further include a polyethylene glycol series solubilizer.

[0065] Exemplarily, the concentration of the solubilizing agent in the acid washing reagent may be 0.02 mg / L.

[0066] Polyethylene glycol series solubilizers can increase the solubility of metal corrosion inhibitors in acidic solutions, and further optimize the corrosion inhibition effect of metal corrosion inhibitors on metal surfaces during pickling treatment.

[0067] Exemplarily, the solubilizing agent may be PEG-400, ie polyethylene glycol 400.

[0068] The present invention also provides a use of the pickling reagent as described in any one of the above items in pickling of metal materials.

[0069] The method comprises the steps of: mixing the metal corrosion inhibitor with the pickling medium to prepare the pickling reagent;

[0070] The pickling agent is used to carry out pickling treatment on the metal material, the pickling treatment lasts for 10 to 96 hours, and the pickling treatment temperature is 10 to 35°C.

[0071] The step of using the pickling agent to pickle the metal material comprises: immersing the metal material that has been subjected to grinding, degreasing and drying treatments in sequence in the pickling agent.

[0072] The grinding process includes: using metallographic sandpaper to grind the surface of the metal material to be smooth and flat.

[0073] The degreasing treatment may include: using petroleum ether and anhydrous ethanol to remove grease on the surface of the metal material, then washing with deionized water, drying and weighing for later use.

[0074] The pickling treatment is completed after the metal material is immersed in the pickling agent for 10 to 96 hours at a temperature of 10 to 35°C.

[0075] In some embodiments, the metal material after pickling treatment can be taken out, rinsed with distilled water, and then repeatedly cleaned with petroleum ether and anhydrous ethanol, and weighed after drying. The metal corrosion inhibition rate is calculated using the weight loss of the test piece.

[0076] In some embodiments, the metal material includes carbon steel, copper and alloys thereof.

[0077] Exemplarily, the metal material may be Q235 carbon steel.

[0078] In order to facilitate those skilled in the art to further understand the present invention, examples are given below:

[0079] Example 1: Preparation of Metal Corrosion Inhibitor - N-Benzoyl-O-ethylthiocarbamate

[0080] Add 1.15 parts of 99% pure PEG-400, 8.27 parts of 98% pure NaSCN and 80 parts of 99% pure dichloromethane into a 250mL three-necked flask and mix for a while, then add 14.20 parts of 99% pure benzoyl chloride, and heat to 25°C to react for 3.5 hours. Then add 4.6 parts of 99% pure ethanol into the reaction vessel, heat to 35°C and react for 4 hours. After the reaction is completed, filter and remove salt, and recover dichloromethane by rotary evaporation to obtain a crude product with a purity of 92.03% and a yield based on ethanol of 93.04%. The crude product of N-benzoyl-O-ethylthiocarbamate was purified by recrystallization and then characterized. 1 H NMR Figure 1 shown.

[0081] Example 2: Preparation of Metal Corrosion Inhibitor - N-Benzoyl-O-n-propylthiocarbamate

[0082] Add 1.15 parts of 99% pure PEG-400, 8.27 parts of 98% pure NaSCN and 80 parts of 99% pure dichloromethane into a 250mL three-necked flask and mix for a while, then add 14.20 parts of 99% pure benzoyl chloride, and heat to 25°C to react for 3.5 hours. Then add 6.0 parts of 99% pure n-propanol into the reaction vessel, heat to 35°C to react for 4 hours. After the reaction is completed, filter and remove salt, and recover dichloromethane by rotary evaporation to obtain a crude product with a purity of 93.65% and a yield of 89.23% based on n-propanol. The crude product of N-benzoyl-O-n-propylthiocarbamate was purified by recrystallization and then characterized. 1 H NMR Figure 2 shown.

[0083] Example 3: Preparation of Metal Corrosion Inhibitor - N-Benzoyl-O-n-butylthiocarbamate

[0084] Add 1.15 parts of 99% pure PEG-400, 8.27 parts of 98% pure NaSCN and 80 parts of 99% pure dichloromethane into a 250mL three-necked flask and mix for a while, then add 14.20 parts of 99% pure benzoyl chloride, and heat to 25°C to react for 3.5 hours. Then add 7.4 parts of 99% pure n-butanol into the reaction vessel, heat to 35°C to react for 4 hours. After the reaction is completed, filter and remove salt, and recover dichloromethane by rotary evaporation to obtain a crude product with a purity of 94.12% and a yield of 93.66% based on n-butanol. The crude product of N-benzoyl-O-n-butylthiocarbamate was purified by recrystallization and then characterized. 1 H NMR Figure 3 shown.

[0085] Example 4: Corrosion Inhibition Performance of N-Benzoyl-O-Ethylthiocarbamate on Carbon Steel Q235

[0086] Refer to the Petroleum and Natural Gas Industry Standard of the People's Republic of China "Evaluation Method of Corrosion Inhibitor Performance for Oilfield Produced Water" (SY / T 5273-2014). Select a Q235 carbon steel standard test piece with a specification of 50mm×10mm×3mm, polish it with metallographic sandpaper until the surface is smooth and flat, remove the surface grease with petroleum ether and anhydrous ethanol respectively, wash with deionized water, dry and weigh for standby use. The Q235 carbon steel standard test piece was soaked in 1M HCl hydrochloric acid pickling reagent for 72h at a temperature of 25°C, wherein the pickling reagent contains 40mg / L of N-benzoyl-O-ethylthiocarbamate prepared in Example 1, 1.2g of PEG-400 is added, and the concentration of PEG-400 is 0.2mg / L. After the test, the carbon steel was taken out, rinsed with distilled water, and then repeatedly washed with petroleum ether and anhydrous ethanol, weighed after drying, and the metal corrosion inhibition rate was calculated using the weight loss of the test piece. The results show that the corrosion inhibition efficiency of carbon steel immersed in the cleaning solution is 89.33%.

[0087] Comparative Example 1: Corrosion inhibition performance of carbon steel Q235 without N-benzoyl-O-ethylthiocarbamate

[0088] Refer to the Petroleum and Natural Gas Industry Standard of the People's Republic of China "Evaluation Method of Corrosion Inhibitor Performance for Oilfield Produced Water" (SY / T 5273-2014). Select a Q235 carbon steel standard specimen with a specification of 50mm×10mm×3mm, polish it with metallographic sandpaper until the surface is smooth and flat, remove the surface grease with petroleum ether and anhydrous ethanol respectively, wash with deionized water, dry and weigh for standby use. The Q235 carbon steel standard specimen was soaked in 1M HCl hydrochloric acid cleaning solution for 72h at a temperature of 25℃, in which the cleaning solution contained 1.2g of PEG-400 and the concentration of PEG-400 was 0.2mg / L. After the test, the carbon steel was taken out, rinsed with distilled water, and then repeatedly washed with petroleum ether and anhydrous ethanol, weighed after drying, and the metal corrosion inhibition rate was calculated using the weight loss of the specimen. The results show that the corrosion inhibition efficiency of carbon steel immersed in the cleaning solution is 15.33%.

[0089] Comparative Example 2: Corrosion Inhibition Performance of N-Benzoyl-O-Ethylthiocarbamate on Carbon Steel Q235 without PEG-400

[0090] Refer to the Petroleum and Natural Gas Industry Standard of the People's Republic of China "Evaluation Method of Corrosion Inhibitor Performance for Oilfield Produced Water" (SY / T 5273-2014). Select a Q235 carbon steel standard specimen with a specification of 50mm×10mm×3mm, polish it with metallographic sandpaper until the surface is smooth and flat, remove the surface grease with petroleum ether and anhydrous ethanol respectively, wash with deionized water, dry and weigh for use. The Q235 carbon steel standard specimen was immersed in 1M HCl hydrochloric acid cleaning solution for 72h at a temperature of 25℃, in which the cleaning solution contained 40mg / L of N-benzoyl-O-ethylthiocarbamate, and no PEG-400 was added. After the test, the carbon steel was taken out, rinsed with distilled water, and then repeatedly washed with petroleum ether and anhydrous ethanol, and weighed after drying. The metal corrosion inhibition rate was calculated using the weight loss of the specimen. The results show that the corrosion inhibition efficiency of carbon steel immersed in the cleaning solution is 82.19%.

[0091] Example 5: Corrosion inhibition performance of N-benzoyl-O-n-propylthiocarbamate on carbon steel Q235

[0092] Refer to the Petroleum and Natural Gas Industry Standard of the People's Republic of China "Evaluation Method of Corrosion Inhibitor Performance for Oilfield Produced Water" (SY / T 5273-2014). Select a Q235 carbon steel standard test piece with a specification of 50mm×10mm×3mm, polish it with metallographic sandpaper until the surface is smooth and flat, remove the surface grease with petroleum ether and anhydrous ethanol respectively, wash it with deionized water, dry it and weigh it for use. Soak the Q235 carbon steel standard test piece in 1M HCl hydrochloric acid pickling reagent for 72h at a temperature of 25°C, wherein the pickling reagent contains 40mg / L of N-benzoyl-O-n-propylthiocarbamate prepared in Example 2, 1.2g of PEG-400 is added, and the concentration of PEG-400 is 0.2mg / L. After the test, take out the carbon steel, rinse it with distilled water, and then repeatedly wash it with petroleum ether and anhydrous ethanol, dry it and weigh it, and calculate the metal corrosion inhibition rate using the weight loss of the test piece. The results show that the corrosion inhibition efficiency of carbon steel immersed in the cleaning solution is 90.12%.

[0093] Example 6: Corrosion Inhibition Performance of N-Benzoyl-O-n-Butyl Thiocarbamate on Carbon Steel Q235

[0094] Refer to the Petroleum and Natural Gas Industry Standard of the People's Republic of China "Evaluation Method of Corrosion Inhibitor Performance for Oilfield Produced Water" (SY / T 5273-2014). Select a Q235 carbon steel standard test piece with a specification of 50mm×10mm×3mm, polish it with metallographic sandpaper until the surface is smooth and flat, remove the surface grease with petroleum ether and anhydrous ethanol respectively, wash it with deionized water, dry it and weigh it for standby use. The Q235 carbon steel standard test piece was soaked in 1M HCl hydrochloric acid pickling reagent for 72h at a temperature of 25°C, wherein the cleaning solution contained 40mg / L of N-benzoyl-O-n-butylthiocarbamate prepared in Example 3, 1.2g of PEG-400, and the concentration of PEG-400 was 0.2mg / L. After the test, the carbon steel was taken out, rinsed with distilled water, and then repeatedly washed with petroleum ether and anhydrous ethanol, weighed after drying, and the metal corrosion inhibition rate was calculated using the weight loss of the test piece. The results show that the corrosion inhibition efficiency of carbon steel immersed in the cleaning solution is 89.28%.

[0095] The present invention innovatively adds acylthiocarbamate corrosion inhibitors to metal pickling reagents and applies them to corrosion inhibitors for carbon steel metal materials. It is found that this type of corrosion inhibitor is mixed with polyethylene glycol compounds, such as PEG-400, and added to a hydrochloric acid solution, which can significantly increase the corrosion inhibition performance of carbon steel materials during the pickling process, and has a relatively broad practical application prospect.

[0096] The above technical solutions of the present invention are only preferred embodiments of the present invention, and the patent scope of the present invention is not limited thereto. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A metal corrosion inhibitor, characterized in that: It is used as a metal corrosion inhibitor for metal corrosion inhibition, and the structure of the metal corrosion inhibitor is shown in Formula I: Among them, R 1 C1~C 16 Alkyl, C2~C 16 Olefin groups, C5~C 16 The ring group, C6~C 16 aromatic groups, C1~C 16 Alkyl, C2~C 16 Olefin groups, C5~C 16 The ring group and the C6~C 16 One of the aromatic groups; R 2 C1~C 16 Alkyl, alkylaryl, C1~C 16 One of an alkyl group and an alkylaryl group carrying a substituent; The substituent includes at least one of a C1-C6 alkyl group, a C1-C6 alkoxy group, a C1-C6 alkylthio group, and a hydroxyl group.

2. The metal corrosion inhibitor according to claim 1, characterized in that R 1 Including one of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, pentyl, isopentyl, sec-pentyl, neopentyl, n-hexyl, isohexyl, sec-hexyl, n-heptyl, isoheptyl, n-octyl, isooctyl, n-nonyl, undecyl, pentadecyl, ethoxyethyl, tert-butoxyethyl, phenyl, benzyl, phenethyl, styryl, m-methylphenyl, p-ethylphenyl, p-methoxyphenyl, cyclopropyl, cyclopentyl, cyclohexyl, propenyl or propynyl.

3. The metal corrosion inhibitor according to claim 2, characterized in that R 1 is one of n-octyl, isooctyl, undecyl, phenyl or benzyl; R 2 It is one of methyl, ethyl, n-propyl, n-butyl, isobutyl, n-hexyl, phenyl and benzyl.

4. The metal corrosion inhibitor according to claim 3, characterized in that The R 1 Including phenyl, the R 2 Includes one of ethyl, n-propyl and n-butyl.

5. A method for preparing a metal corrosion inhibitor as claimed in claim 4, characterized in that: The method comprises the steps of: mixing a solubilizing agent, NaSCN, dichloromethane and benzoyl chloride, heating the mixture to 20-30° C. and reacting the mixture for 3-4 hours to obtain a pretreatment agent; Adding an alcohol compound to the pretreatment agent, heating to 30-40° C. for reaction for 3-5 hours, and then filtering to remove salt and solvent in sequence to obtain the metal corrosion inhibitor; the alcohol compound includes one of ethanol, n-propanol, and n-butanol; The molar ratio of the benzoyl chloride, the NaSCN, and the alcohol compound is 1:0.95-1.25:1.0-2.0; the amount of the dichloromethane is 20-50 mL / 0.1 mol of the benzoyl chloride; and the amount of the solubilizer is 0.1-1 g / 0.1 mol of the benzoyl chloride.

6. A pickling reagent, characterized in that Its composition includes a pickling medium and the metal corrosion inhibitor described in any one of claims 1 to 4, the concentration of the metal corrosion inhibitor in the pickling reagent is 10 to 200 mg / L, the concentration of the pickling medium in the pickling reagent is 0.5 to 2 mol / L, and the type of the pickling medium includes hydrochloric acid or sulfuric acid.

7. The pickling reagent according to claim 6, characterized in that The acid washing reagent also includes a polyethylene glycol series solubilizer, and the concentration of the solubilizer is 0.01-0.5 mg / L.

8. Use of the pickling reagent according to any one of claims 6 to 7 in pickling of metal materials, comprising the steps of: mixing the metal corrosion inhibitor with the pickling medium to prepare the pickling reagent; The pickling agent is used to carry out pickling treatment on the metal material, the pickling treatment lasts for 10 to 96 hours, and the pickling treatment temperature is 10 to 35°C.

9. The use according to claim 8, characterized in that: The metal material includes carbon steel.

10. The use according to claim 9, characterized in that: The step of using the pickling agent to pickle the metal material comprises: immersing the metal material that has been subjected to grinding, degreasing and drying treatments in sequence in the pickling agent.

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