Hydrophobic film-forming agent and method for forming a hydrophobic film using the same, and corrosion and wear prevention agent and method for preventing corrosion and wear using the same

Abstract

To provide a hydrophobic film formation agent capable of reducing trouble at operation or load of maintenance by preventing corrosion of components, crack corrosion by scale adherence or catching rust and pollution generating on products in a plant coexisting with water except pure water and soft water other than a boiler facility, particularly in a continuous casting facility, and to provide a hydrophobic film formation method and a corrosion / wear preventive agent using the film formation agent, and a corrosion / wear prevention method using the preventive agent.SOLUTION: There are provided a hydrophobic film formation agent which is characterized by including the salt of organic dibasic acid and ammonia-based compound as an active ingredient for a component of the plant coexisting with water (except pure and soft water), and a corrosion / wear preventive agent characterized by further including a neutralizer capable of controlling the M alkalinity of a target water as an active ingredient in the above hydrophobic film formation agent for the component of the plant coexisting with the above water. The above-mentioned problem is solved by the hydrophobic film formation agent and corrosion / wear preventive agent.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hydrophobic film-forming agent, a method for forming a hydrophobic film using the same, and a corrosion and wear inhibitor and a method for preventing corrosion and wear using the same.The present invention can be suitably used, for example, in the production of steel by a continuous casting method, for preventing corrosion and wear of metal members in continuous casting equipment that are exposed to cooling water sprayed on cast steel. [Background technology]

[0002] Until the 1960s, the mainstream steelmaking method was to pour molten steel into a mold, let it cool naturally, and then reheat the resulting ingot to make billets by rolling it in a blooming mill. However, since the 1970s, the continuous casting method, which produces billets directly from molten steel, has become more widespread. In continuous casting, molten steel is first poured from a ladle into a tundish (trough). A fusible powder is added to the molten steel in the tundish as a release agent to prevent oxidation of the surface and provide lubrication. The molten steel is then poured into a mold through one or more openings at the bottom of the tundish. The mold, cooled by primary cooling water, cools the molten steel, and solidification begins from the sides of the molten steel. The solidified steel (slab, billet, or bloom) is then sent to a secondary cooling spray zone. This zone consists of rolls to prevent the billet from expanding and a spray device that sprays secondary cooling water on the sides of the billet to promote solidification. The rolls are arranged, for example, in a curved mold. The billet poured vertically is bent and horizontalized by the rolls, and then drawn out by the horizontal rolls. The fully solidified billet is then cut to the appropriate length.

[0003] Fluoride powders, typically 3 to 15% by weight (equivalent to fluorine) are added to the molten steel in the tundish. These fluoride powders melt in contact with the molten steel in the mold, normalizing the surface of the molten steel. After adhering to the billet surface, the billet passes through the mold, and most of the powder is detached from the billet by the secondary cooling water. The fluoride reacts with the secondary cooling water to produce hydrofluoric acid, which significantly lowers the pH of the cooling water and corrodes metal components near the cooling zone, such as rolls, support members, spray nozzles, and piping, significantly shortening the service life of the continuous casting equipment. For this reason, various attempts have been made to prevent the adverse effects of hydrofluoric acid from the powder.

[0004] For example, the applicant of the present application has proposed a method for preventing corrosion and wear in continuous casting equipment having foot rolls and multiple segments, in which cooling water sprayed on steel is sampled for each foot roll and segment, its M alkalinity is measured, and if the measured M alkalinity is less than 10 mg CaCO3 / L, an alkali metal bicarbonate salt is added to the cooling water before spraying on the relevant foot roll or segment to adjust the M alkalinity to 10 mg CaCO3 / L or more (JP 2007-125570 A: Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-125570 Summary of the Invention [Problem to be solved by the invention]

[0006] On the other hand, in order to improve the productivity of continuous casting products, efforts are being made to increase the size of equipment (facilities) and production speeds, which makes production conditions more severe, and there is a problem that the above-mentioned prior art does not provide sufficient corrosion and wear prevention effects. On the other hand, even in technical fields that handle non-ferrous metals and ceramics other than steel, such as the above-mentioned continuous casting, the components of plants and their peripheral equipment can come into contact with water and its vapor (steam), causing corrosion and wear, and there is a need to prevent this.

[0007] Such plants include facilities for high-temperature processing and cutting. For example, cooling water for the rotary blades used in cutting processes can splash or evaporate and adhere to the equipment and surrounding structural materials, causing corrosion, particularly in facilities that involve high-temperature heating. Cooling water can also adhere to the processed product itself, reducing its value. The above-mentioned problems do not usually occur in boiler facilities that use pure water or soft water, where water quality control is strictly regulated by industrial standards, but are likely to occur in facilities that use general tap water or industrial water.

[0008] Therefore, the present invention has been made in consideration of the above-mentioned problems and current state of the prior art, and has an object to provide a hydrophobic film-forming agent, a hydrophobic film-forming method using the same, and a corrosion and wear inhibitor and a corrosion and wear prevention method using the same, which can reduce troubles during operation and the burden of maintenance by preventing corrosion of constituent materials (metal members), crevice corrosion due to scale adhesion, and transfer of rust and dirt to products in plants that coexist with water other than pure water and soft water, excluding boiler equipment, and particularly continuous casting equipment. [Means for solving the problem]

[0009] As a result of extensive research into solving the above problems, the inventors of the present invention have found that (1) by using a hydrophobic film-forming agent containing a salt of an organic dibasic acid and an ammonia-based compound in water used in a plant that coexists with water (excluding pure water and soft water), a film is formed on the surface of structural materials, improving water repellency and inhibiting corrosion of the structural materials, and (2) by using a corrosion and wear inhibitor that further contains a neutralizing agent that can adjust the M alkalinity of the target water in addition to the hydrophobic film-forming agent, corrosion and wear of structural materials can be prevented, leading to the completion of the present invention.

[0010] Thus, according to the present invention, there is provided a hydrophobic film-forming agent for use on plant components that coexist with water (excluding pure water and soft water), which agent is characterized by containing, as an active ingredient, a salt of an organic dibasic acid and an ammonia-based compound.

[0011] Furthermore, according to the present invention, there is provided a corrosion and wear inhibitor for plant components that coexist with water (excluding pure water and soft water), characterized in that the hydrophobic film-forming agent further contains, as an active ingredient, a neutralizing agent capable of adjusting the M alkalinity of the target water.

[0012] Furthermore, according to the present invention, there is provided a method for forming a hydrophobic film, which comprises adding the above-mentioned hydrophobic film forming agent to water (excluding pure water and soft water) that coexists with a plant, and forming a hydrophobic film on the constituent materials of the plant.

[0013] Furthermore, according to the present invention, there is provided a method for preventing corrosion and wear of the components of a plant, which comprises adding the above-mentioned corrosion and wear inhibitor to water (excluding pure water and soft water) that coexists with the plant and adjusting the M alkalinity of the water to 20 to 150 mgCaCO3 / L. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a hydrophobic film-forming agent, a hydrophobic film-forming method using the same, a corrosion and wear inhibitor, and a corrosion and wear prevention method using the same, which can reduce operational troubles and the burden of maintenance by preventing corrosion of constituent materials (metal members), crevice corrosion due to scale adhesion, and transfer of rust and stains to products in plants that coexist with water other than boiler equipment and other than pure water and soft water, particularly in continuous casting equipment. Although the mechanism of hydrophobic film formation in the present invention is not clear, the inventors believe that the organic dibasic acid, ammonia-based compound, and salts formed by them act to adsorb organic dibasic acid molecules, which are hydrophobic molecules, to the metal surface, thereby forming a hydrophobic film on the surface of the plant's components, imparting water repellency and protecting them from water that comes into contact with them, i.e., repelling water and preventing attack such as corrosion. Furthermore, it is believed that the prevention of corrosion and wear in the present invention is achieved by the coexistence of a neutralizing agent that adjusts the M alkalinity of the water coexisting with the plant to a state in which corrosion and wear are less likely to occur.

[0015] The hydrophobic film-forming agent of the present invention exhibits the above-mentioned effects more effectively when any one of the following conditions is satisfied. (1) The organic dibasic acid is an organic dibasic acid having 8 to 12 carbon atoms. (2) The ammonia-based compound is ammonia or a low-molecular-weight amine compound having 1 to 4 carbon atoms. The corrosion and wear inhibitor of the present invention exhibits the above-mentioned effects more effectively when the following conditions are met. (3) The neutralizing agent is at least one selected from alkali metal bicarbonate salts, alkaline earth metal bicarbonate salts, and low-molecular-weight amine compounds having 1 to 4 carbon atoms. The corrosion and wear prevention method of the present invention exhibits the above-mentioned effects more effectively when any one of the following conditions is satisfied. (4) The plant is a continuous casting facility or a hot rolling facility. (5) The corrosion and wear inhibitor is added to the cooling water before the process in which steam is generated in the continuous casting equipment. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram of a circular arc curved continuous casting machine. DETAILED DESCRIPTION OF THE INVENTION

[0017] 1. Hydrophobic film forming agent The hydrophobic film-forming agent of the present invention is a hydrophobic film-forming agent for use on plant components that coexist with water (excluding pure water and soft water), characterized by containing a salt of an organic dibasic acid and an ammonia-based compound as an active ingredient.

[0018] [Organic dibasic acids] The organic dibasic acid is not particularly limited as long as it can act together with the ammonia-based compound to form a hydrophobic film on the surface of the plant constituent materials. Examples of organic dibasic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, dodecanedioic acid, tridecanedioic acid, maleic acid, fumaric acid, citraconic acid, mesaconic acid, itaconic acid, glutaconic acid, and acetylenedicarboxylic acid. Of these, organic dibasic acids having 8 to 12 carbon atoms are preferred. In the present invention, one of these may be used alone, or two or more of these may be used in combination. Among these organic dibasic acids, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, and dodecanedioic acid are preferred in terms of the uniformity and effectiveness of the hydrophobic film formed by the salt with an ammonia-based compound, and azelaic acid and sebacic acid, which are dibasic acids having 9 or 10 carbon atoms, are particularly preferred because they have relatively high solubility as salts of ammonia-based compounds and do not have excessively large molecular weights, and are less likely to cause stains due to excessive deposition of the salt itself.

[0019] For example, the solubilities of azelaic acid and sebacic acid in 100 g of water are thought to be about 0.24 g and 0.1 g, respectively, and the solubilities of ammonium azelaate and ammonium sebacate in 100 g of water are thought to be about 2.5 g and 1 g, respectively. In the present invention, the solubility of the salt of an ammonia compound of an organic dibasic acid in 100 g of water is preferably about 0.5 to 2 g.

[0020] [Ammonia compounds] The ammonia-based compound is not particularly limited as long as it can act together with the organic dibasic acid to form a hydrophobic film on the surface of the plant constituent materials. Examples of ammonia compounds include ammonia, methylamine, ethylamine, dimethylamine, diethylamine, ethylmethylamine, trimethylamine, propylamine, isopropylamine, 1-butanamine, 2-butanamine, isobutylamine, tert-butylamine, hexylamine, cyclohexylamine, methylpropylamine, triethylamine, methylethylamine, diethylamine, and methoxypropylamine. In the present invention, the term "ammonia-based compound" refers to ammonia and the above-mentioned amine compounds that can form an ammonium salt of an organic dibasic acid as described below.

[0021] Among these, ammonia and low molecular weight amine compounds having 1 to 4 carbon atoms, such as methylamine, ethylamine, dimethylamine, trimethylamine, propylamine, isopropylamine, 1-butanamine, 2-butanamine, diethylamine, isobutylamine, tert-butylamine and methylethylamine are preferred. In the present invention, one of these, including ammonia, can be used alone, or two or more of these can be used in combination. Among these ammonia-based compounds, ammonia, methylamine, ethylamine, dimethylamine, trimethylamine, propylamine, and isopropylamine are preferred in terms of the uniformity of the hydrophobic coating formed by the salt with the organic dibasic acid and its effectiveness, and ammonia is particularly preferred in terms of its solubility as a salt with the organic dibasic acid and the fact that the salt itself is less likely to deposit in excess and cause stains.

[0022] [Composition ratio and dosage form of organic dibasic acid and ammonia compound] The compounding ratio of the organic dibasic acid to the ammonia-based compound is preferably 1:2-3, and particularly preferably 1:2-2.5, which is close to the theoretical ratio, in order to increase the alkali side from the molar ratio since the neutralized salt forms a film. The hydrophobic film-forming agent of the present invention is usually an aqueous preparation, and can be prepared by dissolving an organic dibasic acid and an ammonia-based compound in water. An organic dibasic acid and an ammonia-based compound form an ammonium salt of the organic dibasic acid in water. Therefore, in the present invention, an ammonium salt of the organic dibasic acid may be used. For example, Nalco 10000 manufactured by Nalco Corporation, which is commercially available in the form of an aqueous solution of an ammonium salt of an organic dibasic acid, can be used. The concentration of the active ingredient in the hydrophobic film-forming agent of the present invention is usually about 0.5 to 2% by mass, taking into consideration the stability of the active ingredient, the transportation costs of the preparation, and the like.

[0023] [Other active ingredients] The hydrophobic film-forming agent of the present invention may be used in combination with other agents used in the art, if necessary, within the range that does not impair the effects of the present invention. Such agents include scale inhibitors and slime control agents.

[0024] Examples of scale inhibitors include polymers composed of monomers such as acrylic acid, methacrylic acid, and maleic acid; organic phosphonic acid compounds such as 1,1-hydroxyethanediphosphonic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, and their sodium salts; and organic phosphinic acid compounds such as bis(poly-2-carboxyethyl)phosphinic acid, acrylic acid-2-acryloylamino-2-methyl-1-propanesulfonic acid-hypophosphorous acid addition polymers, and their sodium salts.

[0025] Slime removers include monochloroglyoxime, dichloroglyoxime, methylene bisthiocyanate, 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, α-chlorobenzaldoxime, bis(tribromomethyl)sulfone, 2,2-dibromo-3-nitrilopropionamide, 2-bromo-2-nitro-1-propane-1,3-diol, 2,2-dibromo-2-nitro-1-ethanol, 2-bromo-2-nitro-1,3-diacetoxypropane, 1,2-bis(bromoacetoxy)ethane, 1,2-bis(bromoacetoxy)propane Organic compounds such as pan, 1,4-bis(bromoacetoxy)-2-butene, 1,2,3-tris(bromoacetoxy)propane, 5-chloro-2,4,6-trifluoroisophthalonitrile, 6-chloro-2,4-difluoro-6-methoxyisophthalonitrile, 3,3,4,4-tetrachlorotetrahydrothiophene-1,1-dioxide, β-bromo-nitrostyrene, 5-bromo-5-nitro-1,3-dioxane, bis(trichloromethyl)sulfone, and 4,5-dichloro-2-n-isothiazolin-3-one; and inorganic compounds such as hydrogen peroxide, peracetic acid, hypochlorite, and ozone.

[0026] When other chemicals such as the scale inhibitors and slime control agents are added, the amount of these chemicals added may be controlled by adding a water-soluble fluorescent tracer to the cooling water in an amount proportional to the amount of these chemicals added. Examples of such methods include the "Method for Monitoring Industrial Water Systems" described in Japanese Patent Publication No. 6-11437 and the "Method for Continuous On-Stream Monitoring of Cooling Tower Water" described in Japanese Patent Publication No. 2771611.

[0027] [Target plant] The target plant for the hydrophobic film-forming agent of the present invention is not particularly limited, as long as it is a plant in which water (excluding pure water and soft water) coexists. As described above, boiler facilities are subject to strict industrial standards for water quality control and use pure water or softened water, so the problems of the present invention do not usually occur in boiler facilities, and therefore are excluded from the scope of the present invention. In other words, the hydrophobic film-forming agent of the present invention can be applied to all plants that use general drinking water or industrial water, in which the problems of the present invention occur. Examples of such plants include continuous casting facilities for producing slabs, blooms, and burettes in the manufacturing process of stainless steel products and iron and steel products; hot rolling facilities and blooming facilities for producing thick plates and thin plates; hot rolling facilities and continuous casting facilities for producing H-beams, steel bars, wire, and seamless pipes; continuous casting and hot rolling facilities for producing copper and copper alloys; cutting equipment for various ceramic cutting processes that reach high temperatures, saw blades, and facilities that use water to cool the products being processed.

[0028] 2. Hydrophobic film formation method The hydrophobic film forming method of the present invention is characterized by adding the hydrophobic film forming agent of the present invention to water (excluding pure water and soft water) that coexists with a plant, thereby forming a hydrophobic film on the constituent materials of the plant.

[0029] The method of addition is not particularly limited, and the compound may be added to the target water using existing equipment. The conditions for addition may be appropriately determined depending on the state of the object to which it is added and the desired effect. If the concentration of the hydrophobic film-forming agent is high, it may be diluted with water before use. Generally, the hydrophobic film-forming agent is added so that the concentration of the active ingredient in the target water is 0.003 to 0.3 ppm (= mg / L).

[0030] 3. Corrosion and wear inhibitors The corrosion and wear inhibitor of the present invention is a corrosion and wear inhibitor for plant components that coexist with water (excluding pure water and soft water), characterized in that the hydrophobic film-forming agent of the present invention further contains, as an active ingredient, a neutralizing agent that can adjust the M alkalinity of the target water.

[0031] The neutralizing agent is not particularly limited as long as it does not inhibit film formation by the hydrophobic film-forming agent of the present invention, adjusts the M alkalinity of the target water, and exerts corrosion and abrasion prevention effects on the plant's constituent materials. However, it is preferably at least one selected from alkali metal salts of bicarbonate, alkaline earth metal salts of bicarbonate, and low-molecular-weight amine compounds having 1 to 4 carbon atoms. Examples of alkali metal salts of bicarbonate (hydrogen carbonates) include sodium hydrogen carbonate and potassium hydrogen carbonate. Examples of alkaline earth metal salts of bicarbonate (hydrogen carbonates) include magnesium hydrogen carbonate and calcium hydrogen carbonate.

[0032] Examples of low-molecular-weight amine compounds having 1 to 4 carbon atoms include methylamine, ethylamine, dimethylamine, diethylamine, ethylmethylamine, trimethylamine, propylamine, isopropylamine, 1-butanamine, 2-butanamine, isobutylamine, and tert-butylamine. In the present invention, one of these neutralizing agents can be used alone, or two or more can be used in combination. In particular, when the M alkalinity is rapidly reduced and the pH is significantly reduced, it is effective to use a combination of two or more of the above inorganic hydrogen carbonates and amine compounds. Among these, sodium bicarbonate, potassium bicarbonate, magnesium bicarbonate, calcium bicarbonate, methylamine, ethylamine, dimethylamine, trimethylamine, propylamine, and isopropylamine are preferred because of their great effect in increasing M alkalinity, and sodium bicarbonate and potassium bicarbonate are particularly preferred because of their high buffering power, low cost, and safe effect in increasing M alkalinity.

[0033] [Dosage form] The corrosion and wear inhibitor of the present invention is usually an aqueous formulation, and can be prepared by dissolving a neutralizing agent in the hydrophobic film-forming agent of the present invention. Alternatively, the hydrophobic film-forming agent of the present invention may be used in a two-liquid formulation consisting of an aqueous formulation containing only a neutralizing agent. Furthermore, when the ammonia-based compound of the hydrophobic film-forming agent of the present invention and the neutralizing agent capable of adjusting the M alkalinity of the target water of the corrosion and wear inhibitor of the present invention are the same compound, and when the hydrophobic film-forming agent of the present invention contains an excess of the ammonia-based compound, it can become the corrosion and wear inhibitor of the present invention. The concentration of the active ingredient in the corrosion and wear inhibitor of the present invention is usually about 0.5 to 40% by mass, taking into consideration the stability of the active ingredient, the cost of transporting the formulation, and the like.

[0034] [Other active ingredients] The corrosion and wear inhibitor of the present invention may be used in combination with other agents used in the relevant fields as needed, provided that the effects of the present invention are not impaired. Other active ingredients are the same as the hydrophobic film-forming agent described above.

[0035] [Target plant] The target plant for the corrosion and wear inhibitor of the present invention is not particularly limited as long as it is a plant in which water (excluding pure water and soft water) coexists, and similar to the above-mentioned method for forming a hydrophobic film, it can be suitably used in continuous casting equipment or hot rolling equipment in particular.

[0036] 4. Corrosion and wear prevention methods The corrosion and wear prevention method of the present invention is characterized by adding the corrosion and wear inhibitor of the present invention to water (excluding pure water and soft water) that coexists with a plant, and adjusting the M alkalinity of the water to 20 to 150 mgCaCO3 / L, thereby preventing corrosion and wear of the components of the plant.

[0037] The method of addition is not particularly limited, and it may be added to the target water using existing equipment so that the M alkalinity of the target water becomes 20 to 150 mgCaCO3 / L. If the target water's M-alkalinity is less than 20 mg CaCO3 / L, corrosion and wear may increase. On the other hand, if the target water's M-alkalinity is more than 150 mg CaCO3 / L, hardness components dissolved in the water may precipitate. The preferred target water M-alkalinity is 30 to 130 mg CaCO3 / L. Here, "M alkalinity" refers to the amount of acid required to neutralize the target water to the color change point (pH 4.8) of the methyl red-bromcresol green mixed indicator, and indicates the total amount of alkali, including weakly alkaline components, in the target water. This "M alkalinity" is also called "acid consumption pH 4.8" and is expressed in mgCaCO3 / L (see, for example, JIS B0130).

[0038] The conditions for addition may be appropriately determined depending on the state of the object to which it is added and the desired effect. If the concentration of the hydrophobic film-forming agent is high, it may be diluted with water before use. The corrosion and wear prevention method of the present invention is suitably used when the target plant is a continuous casting facility or a hot rolling facility.

[0039] [One embodiment] The continuous casting equipment to which the corrosion and abrasion prevention method of the present invention can be applied is not particularly limited as long as it is equipment used in the relevant field for continuous casting of steel having foot rolls and a plurality of segments, and specific examples include vertical continuous casting machines such as vertical type, vertical pending type, and vertical progressive pending type, and arc-curving type continuous casting machines such as arc-curving type and multi-stage arc-curving type. The targets for corrosion and wear prevention are metal parts in continuous casting equipment, namely rolls near the cooling zone, support parts, spray nozzles, piping, and walkways for inspection and maintenance, stairs, and work spaces.

[0040] First, the cooling water sprayed onto the steel is sampled for each foot roll and segment, and its M alkalinity is measured. Specifically, the cooling water sprayed onto the steel is sampled for each segment, and its M alkalinity is measured using a known method and device.

[0041] Next, when the measured M alkalinity is less than 20 mgCaCO3 / L, the corrosion and wear inhibitor of the present invention is added to the cooling water before spraying in the corresponding foot rolls and segments to adjust the M alkalinity to 20 to 150 mgCaCO3 / L. That is, when the M alkalinity of the cooling water measured for each foot roll and segment is less than 20 mgCaCO3 / L, the corrosion and wear inhibitor of the present invention is added to the cooling water before spraying in the corresponding segment. Furthermore, if this M alkalinity exceeds 150 mg CaCO3 / L, the pH may rise, which may lead to scaling, and this is also undesirable as it has economic disadvantages.

[0042] Normally, the addition of the corrosion and wear inhibitor of the present invention increases M alkalinity, and decreases depending on the introduction of dilution water into the control water and operational conditions, so the addition of the corrosion and wear inhibitor can be managed manually or automatically based on the lower limit alone, but if M alkalinity increases, it can be adjusted manually or automatically by introducing dilution water into the control water, etc. Also, since there is a correlation between M alkalinity and pH as long as the water quality is stable, it is also possible to obtain the correlation between these two parameters specific to the target plant and automatically control it with pH. If the M alkalinity is within the range of 20 to 150 mgCaCO3 / L, corrosion and wear of metal members in the continuous casting equipment can be effectively prevented. The concentration of the aqueous solution of the corrosion and wear inhibitor depends on the continuous casting equipment and cooling conditions, but a supersaturated solution is preferable. When the active ingredient of the neutralizing agent is sodium bicarbonate, the concentration is about 5% by weight, and when it is potassium bicarbonate, the concentration is about 35% by weight.

[0043] If the continuous casting machine is a vertical type, it is preferable to sample cooling water, measure M alkalinity, and add corrosion and wear inhibitors to the foot roll and the two segments immediately following the foot roll. Furthermore, when the continuous casting machine is a curved arc type continuous casting machine, it is preferable to collect cooling water, measure M alkalinity, and add corrosion and wear inhibitors from the foot roll and the four segments immediately following the foot roll.

[0044] Next, the method for preventing corrosion and abrasion in continuous casting equipment of the present invention will be described in more detail with reference to Figure 1. However, the following description is merely an example of the present invention and does not limit the scope of the present invention.

[0045] FIG. 1 is a schematic diagram of a curved arc type continuous casting machine. In this continuous casting machine, molten steel (MS) is charged into a tundish (T), where it is cooled and passed through a mold (M), foot rolls (FR), and the segments immediately following the foot rolls (Segments 0-4 (S0-S4) in Figure 1), where it is processed into cast steel (slab, CS) and cut to the desired length (the cutting process is not shown). Cooling water (CW) is pumped from a cooling water tank (WT) and sprayed onto the hot steel by the foot rolls (FR) and each segment (S0-S4 in Figure 1), becoming recovered water (recovered cooling water: DW). This water is eventually collected in a scale pit (not shown), and some or all of it passes through a filter (not shown) before returning to the cooling water tank (WT) and being reused as cooling water (CW).

[0046] In the corrosion and abrasion prevention method of the present invention, sampling and analysis of the cooling water used in the foot roll (AF) and sampling and analysis of the cooling water used in each segment (segments 0 to 4, A0 to A4 in Figure 1) are carried out, and based on the results, corrosion and abrasion inhibitors are added to the cooling water before spraying the foot roll (CF) and to the cooling water before spraying each segment (segments 0 to 4, C0 to C4 in Figure 1). The above is an example of a curved arc type continuous casting machine, but a vertical type continuous casting machine has a structure in which the curved arc portion of the former is arranged vertically, i.e., in the vertical direction, and has the same basic configuration as the former.

[0047] As described above, in the present invention, it is preferable to add the corrosion and wear inhibitor to the cooling water before the step in which steam is generated in the continuous casting equipment. [Example]

[0048] The present invention will be specifically explained below with reference to test examples, but the present invention is not limited to these examples.

[0049] (Test Example 1: Evaluation of water repellency by measuring the contact angle of a water droplet) In order to confirm the basic effect of the hydrophobic film-forming agent of the present invention, test pieces were treated with water and steam containing the hydrophobic film-forming agent of the present invention, and the contact angle of a water droplet on the surface was measured to evaluate the water-repellent effect. 0.5 L of pure water was placed in a 1 L autoclave, and ammonium azelaate was added as an active ingredient of the hydrophobic film-forming agent so that the concentration in the pure water was 0.1 ppm. A test piece (material: cold-rolled steel plate SPCC No. 400 polished product, dimensions: 30 mm x 50 mm x 1 mm) was immersed in the pure water. At this time, the pH of the water in the autoclave at room temperature (approximately 20°C) was 9.5. The autoclave was then sealed, heated to a temperature of 300°C, and held under high temperature and pressure conditions for 60 minutes to treat the test pieces, after which the autoclave was cooled to room temperature and the test pieces were taken out. Water was dropped onto the surface of the treated test piece, and the water droplet was photographed from the side of the test piece. The angle between the normal to the bottom of the water droplet in the obtained image and the surface of the test piece was measured and recorded as the contact angle (degrees) (Example 1). The test pieces were treated in the same manner as in Example 1, except that they were suspended 20 mm from the water surface in the autoclave so that they were exposed to steam during treatment, and the contact angle of the water droplet was measured (Example 2). A test piece was treated in the same manner as in Example 1, except that ammonium azelaate was not added, and the contact angle of a water droplet was measured (Comparative Example 1). The results obtained are shown in Table 1 together with the treatment conditions.

[0050] [Table 1]

[0051] Table 1 reveals the following: (1) When the test piece was immersed in water to which the hydrophobic film-forming agent of the present invention had not been added (Comparative Example 1), the contact angle did not reach 90 degrees or more, which is empirically considered to provide sufficient water repellency. (2) In contrast, when a test piece was immersed in water containing the hydrophobic film-forming agent of the present invention (Example 1), and when the test piece was suspended above the water (Example 2), a large contact angle of 110 degrees or more was obtained, and a sufficient water-repellent film was formed on the surface of the test piece.

[0052] (Test Example 2: Evaluation of corrosion and abrasion effects) In order to confirm the corrosion and wear effects (effects of preventing wall thinning and adhesion of dirt) of the corrosion and wear inhibitor of the present invention, an actual test was carried out for two months in a continuous casting facility at a certain steelworks. As shown in Figure 1, a curved-type continuous casting machine (equipped with a fifth segment (S5) not shown) was used in a steel mill. Test pieces (material: cold-rolled steel plate SPCC No. 400, polished, dimensions: 30 mm × 50 mm × 1 mm) were suspended in each of the following segments: segment 0, segment 1, segment 2, segment 3, segment 4, and segment 5, which are located immediately after the foot rolls. The continuous casting machine was then operated, and the corrosion rate of the test pieces (metal loss rate: daily corrosion loss (MDD), unit: mg / dm2·day) was measured two months after the start of the test (installation of the test pieces) to confirm the corrosion prevention effect.

[0053] The pH and M alkalinity (unit: mgCaCO3 / L) and pH of water sampled during operation three times per month from water sampling pots installed at the foot roll (FR) of the continuous casting machine and in each successive segment (S0 to S5) immediately after the foot roll were measured, and their average values ​​were calculated (Table 2). As an active ingredient of the hydrophobic film forming agent, ammonium azelaate was added (injected) to the cooling water so that the concentration would be 0.06 ppm. In addition, potassium bicarbonate was added (injected) at a concentration of 170 ppm as an active ingredient of a corrosion and wear inhibitor so that the M alkalinity of the cooling water near the upper foot roll was 20 mgCaCO3 / L or more (Example 3). A test was conducted in the same manner as in Example 3 (Example 4), except that ammonium sebacate was added at a concentration of 0.08 ppm instead of ammonium azelaate, and sodium bicarbonate was added at a concentration of 200 ppm instead of potassium bicarbonate. The test was carried out in the same manner as in Example 3, except that the hydrophobic film-forming agent and the corrosion and wear inhibitor were not added (Comparative Example 2: blank). A test was conducted in the same manner as in Example 3, except that no hydrophobic film-forming agent was added and only the corrosion and wear inhibitor was added (Comparative Example 3). The results obtained are shown in Table 2 together with the treatment conditions.

[0054] [Table 2]

[0055] Table 2 reveals the following: (1) When the corrosion and wear inhibitor of the present invention was added (Examples 1 and 2) and when only the active ingredient of the corrosion and wear inhibitor of the present invention was added (Comparative Example 3), treatment was possible with higher pH and M alkalinity than in the case of a blank with no added agent (Comparative Example 2). A higher corrosion inhibition effect was observed compared to the case of a blank with no added agent (Comparative Example 2). However, when the corrosion and wear inhibitor of the present invention was added (Examples 1 and 2), a higher corrosion inhibition effect was observed at a much lower corrosion rate. (2) When the corrosion and wear inhibitor of the present invention was added (Examples 1 and 2), the corrosive environment of the equipment and its surroundings was reduced to a much lower level compared to when only the active ingredient of the conventional corrosion and wear inhibitor of the present invention was added (Comparative Example 3). This can be expected to result in higher levels of corrosion prevention for products, equipment, and ancillary equipment, longer equipment life, improved product yield, significant reductions in maintenance costs, and significant improvements in productivity. [Explanation of symbols]

[0056] MS: Molten steel CS: Cast steel (slab) T: Tundish M: Mold FR: Footroll CW: Cooling water DW: Recovered water (recovered cooling water) WT: Cooling water tank S0~4: Segments 0~4 CF: Adding chemicals to footloor cooling water C0-4: Adding chemicals to the cooling water of segments 0-4 AF: Sampling and analysis of cooling water used in foot rolls A0-4: Sampling and analysis of cooling water used in segments 0-4

Claims

1. A corrosion and wear inhibitor is added to water (excluding pure water and soft water) that coexists with continuous casting equipment or hot rolling equipment, and the M alkalinity of the water is increased to 20 to 150 mg CaCO 3 / L to prevent corrosion and wear of the components of the equipment, The corrosion and wear inhibitor is a hydrophobic film-forming agent containing as an active ingredient a salt of an organic dibasic acid and an ammonia-based compound (wherein R 3 -N(R 4 )-R 5 (R 3 , R 4 , R 5 are hydrogen atoms or alkyl or alkenyl groups having 1 to 18 carbon atoms, and the total number of carbon atoms of R 3 , R 4 , and R 5 is 16 or more) and a higher alkylamine represented by R 6 -O(A 1 O) n -R 7 (R 6 is an alkyl or alkenyl group having 1 to 9 carbon atoms, phenyl group, or alkylphenyl group, alkenylphenyl group, or alkyloxyphenyl group having 7 to 11 carbon atoms; R 7 is a hydrogen atom, or alkyl or alkenyl group having 1 to 4 carbon atoms; A 1 is an alkylene group having 2 to 4 carbon atoms; n is alkylene oxide A 1 represents the average number of moles of O added, and is a number from 1 to 20. However, the same alkylene oxide may be added alone, or two or more types of alkylene oxides may be added in combination.) and a neutralizing agent capable of adjusting the M alkalinity of the water, The hydrophobic film-forming agent is added to the water to a concentration of 0.003 to 0.3 ppm. Corrosion and wear prevention methods.

2. 2. The method for preventing corrosion and wear according to claim 1, wherein the corrosion and wear inhibitor is added to cooling water prior to a process in which steam is generated in the facility.

3. A corrosion and wear prevention method according to claim 1 or 2, wherein the organic dibasic acid is an organic dibasic acid having 8 to 12 carbon atoms.

4. A corrosion and wear prevention method described in any one of claims 1 to 3, wherein the ammonia-based compound is ammonia or a low-molecular-weight amine compound having 1 to 4 carbon atoms.

5. A corrosion and wear prevention method described in any one of claims 1 to 4, wherein the neutralizing agent is at least one selected from alkali metal salts of bicarbonate, alkaline earth metal salts of bicarbonate, and low molecular weight amine compounds having 1 to 4 carbon atoms.

6. A hydrophobic film-forming agent containing as an active ingredient a salt of an organic dibasic acid and an ammonia-based compound (wherein the active ingredient is a higher alkylamine represented by R3-N(R4)-R5 (R3, R4, R5: hydrogen atom, or an alkyl or alkenyl group having 1 to 18 carbon atoms, and the total number of carbon atoms of R3, R4, and R5 is 16 or more) and R6-O(A1O)n-R7 (R6: alkyl or alkenyl group having 1 to 9 carbon atoms, phenyl group, or alkylphenyl group, alkenylphenyl group, or alkyloxyphenyl group having 7 to 11 carbon atoms; R7: hydrogen atom, or alkyl or alkenyl group having 1 to 4 carbon atoms; A1: alkylene group having 2 to 4 carbon atoms; n: alkylene oxide A1). represents the average number of moles of O added, and is a number from 1 to 20. However, the same alkylene oxide may be added alone, or two or more types of alkylene oxides may be added in combination. A neutralizer that can adjust the M alkalinity of the target water; 3. A corrosion and wear inhibitor for use in the method of claim 1 or 2, comprising:

7. A corrosion and wear inhibitor according to claim 6, wherein the organic dibasic acid is an organic dibasic acid having 8 to 12 carbon atoms.

8. A corrosion and wear inhibitor according to claim 6 or 7, wherein the ammonia-based compound is ammonia or a low molecular weight amine compound having 1 to 4 carbon atoms.

9. A corrosion and wear inhibitor described in any one of claims 6 to 8, wherein the neutralizing agent is at least one selected from alkali metal salts of bicarbonate, alkaline earth metal salts of bicarbonate, and low molecular weight amine compounds having 1 to 4 carbon atoms.

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