JP2014129579A - Method for manufacturing a steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a steel sheet entailing a tenuous effluent treatment load and capable of reducing the energy cost for drying a post-wash steel sheet, etc.SOLUTION: The provided method for manufacturing a steel sheet is a method for manufacturing a steel sheet including (1) a washing step of washing a steel sheet having been cold-rolled, (2) a rinsing step of rinsing the steel sheet having undergone the washing step (1), and (3) a drying step of drying the steel sheet having undergone the rinsing step (2). The rinsing step (2) includes one or more rinsing treatments, wherein a rinsing agent α used for the final rinsing treatment includes a component (a) expressed by the following general formula: N(RRRR)Xand a component (b) expressed by the following general formula: R-O-(AO)H. The combined concentrations of the component (a) and the component (b) within the rinsing agent α are 150 mg/kg or below, the cation concentration of the inorganic salt of the rinsing agent α is 0.12 mmole/kg or above and 100 mmole/kg or below, and the sulfate ion concentration thereof is 1.5 mmole/kg or below.

Description

  The present invention relates to a method for manufacturing a steel sheet.

  When manufacturing a cold-rolled steel sheet and a cold-rolled coil, it goes through various processing steps. There is an acid cleaning step for removing the oxide layer, or an alkali cleaning step for removing rolling oil and rust preventive oil. In these cleaning steps, an acidic or alkaline cleaning solution is rinsed with warm water and dried with hot air. Since rust is generated when the drying is insufficient, draining to remove water adhering to the steel sheet is an important process, and various draining methods are implemented. Water is squeezed mechanically by a rubber roll called a ringer roll, or an air wiper is attached before hot air drying to blow off water adhering to the steel plate as much as possible. Further, the temperature of the rinsing water when rinsing the cleaning liquid is generally 70 ° C. or higher in order to improve the drying property. However, since a large amount of water is used for this rinsing, it takes a lot of energy costs to raise the temperature to a predetermined temperature.

  In Patent Document 1, in order to suppress the use of rinsing water, as a method of draining water by repelling the steel sheet surface, as an aqueous draining agent that can prevent the occurrence of rust even when applied to metal, amine or / And a drainer characterized by comprising a salt of an imine and an aliphatic carboxylic acid as an active ingredient.

  Patent Document 2 has excellent safety, no environmental pollution, excellent draining performance, suppresses the occurrence of water bleeding, prevents discoloration and prevents rust in metal parts, and is a component of drainer by drying. A draining agent containing a specific nitrogen-containing compound is disclosed as a draining agent that volatilizes and does not easily remain on the surface of the part.

  In Patent Document 3, there is no environmental pollution due to safety, and when used in the cleaning process, the surfaces of various parts to be processed are hydrophobized, and the amount of water adhering to the parts in the last pure water replacement is specified. Reduces drying time by preventing generation of water spots, and also has a rust-proofing effect on metal parts. As a surface treatment agent that can prevent wetting and spreading of the adhesive, a draining agent containing a compound having a specific amino group or quaternary ammonium group is disclosed.

  In Patent Document 4, the surface of a steel sheet can be made water-repellent with a small addition amount, a good draining property can be obtained even at a low temperature of 40 ° C. or less, energy cost can be reduced, drying load can be reduced, and water remains. As a rinsing agent composition for a steel sheet, which has a good rust-preventing effect even in the case of being excellent, and also has excellent antifoaming properties, a rinsing agent composition for a steel sheet containing a specific cationic compound and further a specific nonionic compound Is disclosed.

JP-A-6-238102 JP-A-9-255940 Japanese Patent Laid-Open No. 9-57005 JP 2006-265726 A

  Patent Documents 1 to 4 describe a draining agent and a steel sheet rinsing agent containing a specific amine compound and a specific nonionic surfactant. However, in order to make the steel sheet water repellent, it must be used at a certain concentration.

  The object of the present invention is to reduce the load of wastewater treatment by drying water using a low concentration amine compound and a nonionic surfactant than conventional rinsing agents, and to dry washed steel sheets and the like. It is providing the manufacturing method of a steel plate which can reduce energy cost.

  The present inventor has found that depending on the type of water such as industrial water used in a steel plate manufacturing factory, a sufficient water-repellent effect may be exhibited even when the concentration of the rinse agent is dilute. And paying attention to the cation concentration of the inorganic salt of the rinse agent, by adjusting the cation concentration in a specific range, the usage amount of the amine compound and nonionic surfactant can be reduced, and the steel plate after washing is dried. The knowledge which can reduce energy cost was acquired, and this invention was completed.

The manufacturing method of the steel plate of the present invention includes a cleaning step (1) for cleaning the steel plate after cold rolling, a rinsing step (2) for the steel plate after the cleaning step (1) is performed, and the rinsing step (2 ) Is a method for producing a steel sheet including a drying step (3) for drying the steel plate, wherein the rinsing step (2) includes one or more rinsing processes, and is used for the final rinsing process α Is represented by the following general formula (1):


(Wherein R ¹ represents a hydrocarbon group having 6 to 22 carbon atoms, R ² represents a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms, R ³ and R ⁴ are the same or different, .X indicating the atom or having 1 or more carbon atoms of 3 or less hydrocarbon groups ^-. the component (a) is at least one selected from compounds represented by) indicating an inorganic anion or an organic anion, the following general formula ( 2):
R ⁵ —O— (AO) _m H (2)
(In the formula, R ⁵ is a linear or branched alkyl group or alkenyl group having 8 to 20 carbon atoms, AO is an alkyleneoxy group having 2 to 4 carbon atoms, m is an average added mole number, and 1 or more. And the number of m AOs may be the same or different from each other.) The component (b) is at least one selected from the compounds represented by: The total concentration of the component (b) is 150 mg / kg or less in the rinse agent α, and the cation concentration P _C (mmol / kg) of the inorganic salt of the rinse agent α (P _C = Σ (A × i ) (Wherein A is the concentration of one cation component (mmol / kg), i is the valence of the cation)) is 0.12 mmol / kg or more and 100 mmol / kg or less, and the sulfate ion concentration is 1.5 mmol / Kg or less.

  ADVANTAGE OF THE INVENTION According to this invention, the load of waste_water | drain processing is smaller than the conventional rinse agent, and the manufacturing method of the steel plate which can reduce the energy cost for drying the steel plate etc. after washing | cleaning can be provided.

The manufacturing method of the steel plate of this embodiment includes a cleaning step (1) for cleaning the steel plate after cold rolling, a rinsing step (2) for the steel plate after the cleaning step (1) is performed, and the rinsing step ( A method for producing a steel plate comprising a drying step (3) for drying the steel plate after 2), wherein the rinsing step (2) includes one or more rinsing treatments and is used for the final rinsing treatment Component (a) in which α is at least one selected from the compounds represented by the general formula (1), and component (b) selected from the compounds represented by the general formula (2) ), And the total concentration of the component (a) and the component (b) is 150 mg / kg or less in the rinse agent α, and the cation concentration P _C (mmol) of the inorganic salt of the rinse agent α _{/ kg) (P C = Σ} (A × i) ( in the formula, A Kachio 1 component concentration (mmol / kg), i is a represents the valence of the cation.)) Is 0.12 mmol / kg or more 100 mmol / kg or less, or less concentration of sulfate ion 1.5 mmol / kg.

  According to the steel plate manufacturing method of the present embodiment, the wastewater treatment load and the energy cost for drying the washed steel plate and the like can be reduced. The reason for this effect is not clear, but it is considered as follows.

  By setting the cation concentration of the inorganic salt of the rinsing agent in a specific range, the aggregates such as micelles and vesicles formed by the component (a) and the component (b) are easily adsorbed on the steel sheet surface. Conceivable. That is, if the cation concentration is too low, the aggregates are too stable in water, making it difficult to adsorb on the steel sheet surface. If the cation concentration is too high, coalescence of the aggregates proceeds and the number of aggregates decreases, and the steel sheet surface decreases. It is thought that it becomes difficult to adsorb uniformly. And it is thought that the said component (a) and the said component (b) express water repellency by adsorb | sucking to the steel plate surface, and suppress adhesion of the water on the steel plate surface. Moreover, when there are too many sulfate ions, the said component (a) and a sulfate ion will form a composite_body | complex, and it is thought that adsorption | suction to the steel plate surface of the said component (a) and the said component (b) is inhibited.

[Washing step (1) for washing the steel sheet after cold rolling]
In the cleaning step (1), dirt such as rolling oil adhering to the steel sheet is cleaned with a cleaning agent in accordance with conventional conditions. The steel plate may be any metal, but it is preferable to target iron from the viewpoint of promoting drying and preventing rust. As the cleaning agent, for example, alkaline cleaning agents as described in JP-A-10-280179 and JP-A-10-324900 can be used.

  As the alkaline detergent, an aqueous solution containing an alkaline agent is used. Any alkaline agent can be used as long as it is a water-soluble alkaline agent in order to ensure the removal of oil stains. Specific examples of alkali agents include hydroxides of alkali metals such as sodium hydroxide and potassium hydroxide, silicates such as sodium orthosilicate, sodium metasilicate and sodium sesquisilicate, phosphates such as trisodium phosphate, Examples thereof include carbonates such as disodium carbonate, sodium hydrogencarbonate and dipotassium carbonate, and borate salts such as sodium borate. Two or more water-soluble alkaline agents may be combined. The content of the alkaline agent is preferably 0.1% by mass or more, more preferably 1% by mass or more, and preferably 10% by mass or less, more preferably 3% by mass or less in the alkaline detergent.

  In addition to alkaline agents, alkaline detergents include nonionic surfactants such as polyoxyalkylene alkyl ethers; chelate iron ions etc. by acting on dirt such as iron soap, and easily dissolve the dirt as fatty acid soap Thus, an aliphatic carboxylic acid or a salt thereof can be added from the viewpoint of ensuring stability during storage and stability of effects after storage. In addition, any additive can be added to the alkaline detergent, for example, a commonly used additive such as an organic builder that improves the washability is formulated in consideration of an increase in cost. can do. Although the ratio of components other than the alkali agent in the alkali detergent is appropriately determined, it is preferably 1 part by mass or less, more preferably 0.5 part by mass or less with respect to 1 part by mass of the alkali agent. Moreover, as for the alkali detergent, the ratio of the non volatile matter containing components other than an alkali agent and an alkali agent has preferable 1 mass% or more and 10 mass% or less.

  Examples of the cleaning step (1) include immersion cleaning, spray cleaning, brush cleaning, and electrolytic cleaning. Electrolytic cleaning is a cleaning method in which the steel sheet is made positive (or negative) in the cleaning liquid and a direct current is passed through it. Oxygen (or hydrogen) bubbles generated from the steel sheet by the current are used, and oil stains attached to the steel sheet by physical force. It is a process of removing solid dirt such as iron powder. Moreover, the acid cleaning which removes the oxide film produced | generated on the steel plate surface with an acid cleaning agent may be used.

[Rinsing step after washing step (1) (2)]
In the rinsing step (2), the steel plate after the washing step (1) is rinsed with water or a rinsing agent to remove the washing agent and the remaining rolling oil. The rinse agent used for the treatment (hereinafter referred to as rinse agent α) contains the component (a) and the component (b), and has a cation concentration and a sulfate ion concentration within a specific range.

<Component (a)>
The component (a) contained in the rinse agent α is at least one organic cationic compound selected from the compounds represented by the general formula (1), preferably an alkylamine acid salt and an alkylammonium salt. A salt, more preferably an alkylamine acid salt.

In the general formula (1), R ¹ has 6 or more carbon atoms, and is preferably 8 or more, more preferably 12 or more, still more preferably 16 or more, from the viewpoint of sufficiently hydrophobizing the steel sheet surface. It is 22 or less, preferably 18 or less, and from the viewpoint of sufficiently hydrophobizing the steel sheet surface, a linear or branched alkyl group or alkenyl group is preferable, and a linear alkyl group or alkenyl group is preferable. Examples of R ¹ include hexyl group, octyl group, 2-ethylhexyl group, decyl group, lauryl (dodecyl) group, tridecyl group, myristyl (tetradecyl) group, palmityl (hexadecyl) group, stearyl (octadecyl) group, and behenyl. Group, oleyl group, etc. From the viewpoint of sufficiently hydrophobizing the steel sheet surface, hexyl group, octyl group, lauryl (dodecyl) group, tridecyl group, myristyl (tetradecyl) group, palmityl (hexadecyl) group, stearyl (octadecyl) ) Group, behenyl group and oleyl group are preferred, and palmityl (hexadecyl) group, stearyl (octadecyl) group, behenyl group and oleyl group are more preferred.

In the general formula (1), R ² is preferably a hydrogen atom or 1 or more carbon atoms, and from the viewpoint of sufficiently hydrophobizing the steel sheet surface, preferably 6 or more, more preferably 8 or more, still more preferably 12 or more, and even more. Preferably, it is 16 or more, and is 22 or less, preferably 18 or less. From the viewpoint of sufficiently hydrophobizing the steel sheet surface, a linear or branched alkyl group or alkenyl group is preferable, and a linear alkyl group or An alkenyl group is more preferred. Examples of R ² include hydrogen atom, methyl group, ethyl group, isopropyl group, hexyl group, octyl group, 2-ethylhexyl group, decyl group, lauryl (dodecyl) group, tridecyl group, myristyl (tetradecyl) group, palmityl. (Hexadecyl) group, stearyl (octadecyl) group, behenyl group, oleyl group and the like can be mentioned. R ² is preferably a hydrogen atom from the viewpoint of sufficiently hydrophobizing the steel sheet surface.

R ³ and R ⁴ are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms such as a methyl group, an ethyl group, and an isopropyl group, and from the viewpoint of sufficiently hydrophobizing the steel sheet surface, Atoms are preferred.

Specific examples of X ⁻ include halide ions such as chloride ions and bromide ions, organic anions obtained by removing protons from organic acids such as acetic acid, lactic acid and citric acid, alkyl carbonate ions (CH ₃ CO ₃ ⁻ ), Alkyl phosphate ions and the like can be mentioned, and from the viewpoint of sufficiently hydrophobizing the steel sheet surface, halide ions such as chloride ions and bromide ions and organic anions such as CH ₃ CO ₃ ^— are preferred, and organic anions are preferred. More preferred. Also, sulfate ions can be used. In this case, the concentration of sulfate ions in the rinse agent α is set to 1.5 mmol / kg or less.

As the component (a), dioctylamine, didecylamine, dilaurylamine, dimyristylamine, decyloctylamine, lauryloctylamine, laurylamine, lauryldimethylamine, myristylamine, myristyldimethylamine, palmitylamine, palmityldimethylamine , Stearylamine, stearyldimethylamine, oleylamine, an acid neutralized product of oleyldimethylamine or a quaternary ammonium salt. In the case of an acid neutralized product, at least one of R ² , R ³ and R ⁴ is a hydrogen atom.

  Preferred acids for obtaining an acid neutralized product include hydrochloric acid, nitric acid, phosphoric acid, acetic acid, formic acid, maleic acid, fumaric acid, citric acid, tartaric acid, adipic acid, sulfamic acid, toluenesulfonic acid, lactic acid, pyrrolidone-2 -Carboxylic acid, succinic acid, etc. are mentioned, From a viewpoint of hydrophobizing the steel plate surface sufficiently, hydrochloric acid and acetic acid are preferable, and acetic acid is more preferable. Examples of preferable quaternizing agents for obtaining quaternary ammonium salts include general alkylating agents such as alkyl halides such as methyl chloride, ethyl chloride, methyl bromide and methyl iodide.

  The component (a) is an acid neutralized product of monoalkylamine having 6 to 22 carbon atoms, an acid neutralized product of monoalkylmethylamine having 6 to 22 carbon atoms, and having 6 to 22 carbon atoms. Acid neutralized product of monoalkyldimethylamine, acid neutralized product of dialkylmethylamine having 1 to 22 carbon atoms, acid neutralized product of dialkyldimethylamine having 1 to 22 carbon atoms, carbon number of 6 to 22 Examples thereof include the following alkyltrimethylammonium and dialkylammonium having 1 to 22 carbon atoms. Specifically, dioctylamine hydrochloride, dioctyl dimethyl ammonium chloride, dilauryl dimethyl ammonium chloride, dimyristyl dimethyl ammonium chloride, distearyl dimethyl ammonium chloride, dioleyl dimethyl ammonium chloride, lauryl trimethyl ammonium bromide, stearyl trimethyl ammonium chloride, Oleyltrimethylammonium chloride, lauryltrimethylammonium chloride, laurylamine hydrochloride, stearylamine hydrochloride, oleylamine hydrochloride, laurylamine acetate, myristylamine acetate, myristyltrimethylammonium chloride, palmitylamine acetate , Palmityl trimethyl ammonium chloride, steer Ruamine acetate, stearyltrimethylammonium chloride, oleylamine acetate, hexylamine acetate, behenylamine acetate, behenyltrimethylammonium chloride, and the like. From the viewpoint of sufficiently hydrophobizing the steel sheet surface, hexylamine Acetate, octylamine acetate, laurylamine acetate, hexadecylamine acetate, oleylamine acetate, stearylamine acetate, behenylamine acetate, hexylamine hydrochloride, octylamine hydrochloride Laurylamine hydrochloride, hexadecylamine hydrochloride, oleylamine hydrochloride, stearylamine hydrochloride, and behenylamine hydrochloride are preferable, and hexadecylamine hydrochloride and oleylamine hydrochloride are more preferable.

  The concentration of the component (a) in the rinse agent α is preferably 5 mg / kg or more, more preferably 10 mg / kg or more, still more preferably 20 mg / kg or more, from the viewpoint of sufficiently hydrophobizing the steel sheet surface. 148 mg / kg or less is preferable, 145 mg / kg or less is more preferable, and 120 mg / kg or less is still more preferable from the viewpoint of preventing component (a) from adhering to the steel sheet and hindering subsequent annealing and plating processes. Preferably, 110 mg / kg or less is even more preferable.

<Component (b)>
The component (b) contained in the rinse agent α is at least one compound selected from the compounds represented by the general formula (2).

  In the general formula (2), AO means an alkyleneoxy group having 2 to 4 carbon atoms, such as an ethyleneoxy group, a propyleneoxy group, and a butyleneoxy group. Of these, an ethyleneoxy group and a propyleneoxy group are preferable. There may be a plurality of types of AO. In that case, block bonds, random bonds, alternating bonds, etc. can be used, block bonds and / or random bonds are preferred, and random bonds are more preferred.

In the general formula (2), R ⁵ is a linear or branched alkyl or alkenyl group having 8 or more, preferably 10 or more, more preferably 12 or more, and 20 or less, preferably 18 or less. . Examples of the alkyl group include octyl group, 2-ethylhexyl group, decyl group, sec-decyl group, lauryl (dodecyl) group, sec-lauryl group, myristyl group, cetyl group, palmityl group, stearyl group, and the like. A decyl group, a lauryl group, a myristyl group, a palmityl group, and a stearyl group are preferable, and a myristyl group, a palmityl group, and a stearyl group are more preferable. In the general formula (2), m represents an average added mole number, 1 or more, preferably 3 or more, more preferably 10 or more, and 100 or less, preferably 50 or less, more preferably 40 or less, and still more preferably. Is 30 or less.

  Specifically, the component (b) includes one or more selected from the following.

C _j H _{2j + 1} −O (EO) _pH
C _j H _{2j + 1} −O (EO) _q (PO) _r H (however, EO and PO added as a block)
C _j H _{2j + 1} −O (PO) _r (EO) _q H (however, EO and PO are added as a block)
C _j H _{2j + 1} −O (EO) _s (PO) _t (EO) _u H (however, EO and PO are added as a block)
C _j H _{2j + 1} −O (EO) _q (PO) _r H (however, EO and PO are randomly added)

In the formula of the preceding paragraph, EO is an ethyleneoxy group (C ₂ H ₄ O), PO is a propyleneoxy group (C ₃ H ₆ O), j is an integer of 8 or more and 20 or less, p, q, r, s, t , U is the average number of moles added, p is a number from 3 to 40, q is a number from 1 to 40, r is a number from 1 to 40, s is a number from 1 to 30 and t is A number from 1 to 30; u is a number from 1 to 30; q + r is a number from 3 to 100; and s + t + u is a number from 3 to 100. )

More preferably, 1 or more things chosen from the following are mentioned.
_{C 18 H 35 O (EO)} 4 H, C 12 H 25 O (EO) 5 (PO) 2 (EO) 5 H, C 14 H 29 O (EO) 7 (PO) 2 (EO) 7 H, C ₁₆ H ₃₃ O (EO) ₇ (PO) ₂ (EO) ₇ H, C ₁₆ H ₃₃ O (EO) ₁₀ (PO) ₁₂ H, C ₁₈ H ₃₇ O (EO) ₁₀ (PO) ₉ H, C ₁₈ H ₃₇ O (EO) ₉ (PO) ₆ H (provided that EO and PO are randomly added), C ₁₈ H ₃₇ O (EO) ₁₂ (PO) ₂₁ H (provided that EO and PO are randomly added) ), C ₁₈ H ₃₇ O (EO) ₁₅ (PO) ₁₅ H (however, EO and PO are added as a block).

  Note that (EO) and (PO) indicate that blocks are added in this order unless otherwise specified.

  The concentration of the component (b) in the rinse agent α is preferably 2 mg / kg or more, more preferably 5 mg / kg or more, from the viewpoint of promoting the adsorption of the component (a) and promoting the hydrophobization of the steel sheet, and From the viewpoint of reducing the load of wastewater treatment, and from the viewpoint of not hindering the subsequent annealing process and plating process, it is preferably 145 mg / kg or less, more preferably 140 mg / kg or less, further preferably 130 mg / kg or less, and 80 mg. / Kg or less is more preferred, and 50 mg / kg or less is even more preferred.

  The total concentration of the component (a) and the component (b) in the rinse agent α is 150 mg from the viewpoint of reducing the load of the wastewater treatment, and from the viewpoint of not hindering the subsequent annealing process and plating process. / Kg or less, preferably 100 mg / kg or less, more preferably 60 mg / kg or less.

  The mass ratio of the component (a) to the component (b) is preferably 0.1 or more in terms of (a) / (b) from the viewpoint of expressing water repellency and suppressing the adhesion of water on the steel sheet surface. The above is more preferable, 1.0 or more is further preferable, 5.0 or less is preferable, 3.0 or less is more preferable, and 2.7 or less is further preferable.

The rinse agent α has an inorganic salt cation concentration P _C (mmol / kg) of 0.12 mmol / kg or more and 100 mmol / kg or less. Preparation of inorganic salt cation concentration P _C may be carried out by adjusting the cationic concentration of water in preparing rinses alpha. For example, when the cation concentration of industrial water used in a steel plate manufacturing plant is low, a salt such as sodium chloride, calcium chloride, magnesium chloride or the like can be added to the industrial water to increase the cation concentration. When the cation concentration of the industrial water is high, water having a low cation concentration such as ion exchange water can be mixed with the industrial water to lower the cation concentration. The cations targeted by the cation concentration are inorganic cations, for example, alkali metal ions such as sodium ions and potassium ions, and alkaline earth metal ions such as calcium ions and magnesium ions. The step of measuring the cation concentration of the inorganic salt of water for preparing the rinse agent α, and the rinse agent α used in the rinsing step (2) so that the cation concentration of the inorganic salt falls within the above range based on the measured value. It is preferable to have the process of preparing.

  The rinse agent α exhibits water repellency and suppresses the adhesion of water on the surface of the steel sheet, and the cation concentration Pc of the inorganic salt is 0.12 mmol / kg or more, preferably 0.30 mmol / kg or more. 40 mmol / kg or more is more preferable, 0.55 mmol / kg or more is more preferable, and 100 mmol / kg or less is preferable, 80 mmol / kg or less is preferable, 55 mmol / kg or less is more preferable, and 30 mmol / kg or less is more preferable. 15 mmol / kg or less is even more preferable.

In the present specification, the cation concentration Pc of the inorganic salt is obtained by the following calculation formula (a).
Pc (mmol / kg) = Σ (A × i) (a)
(In the formula, A represents the concentration of one cation component (mmol / kg), and i represents the valence of the cation.)

  In addition, when the sulfate ion exceeds 1.5 mmol / kg, the water repellency of the rinse agent α decreases. This is presumably because when the sulfate ion is too much, the component (a) and the sulfate ion form a complex, and the adsorption of the component (a) and the component (b) to the steel sheet surface is inhibited. The rinse agent α exhibits water repellency and suppresses adhesion of water on the surface of the steel sheet, and the sulfate ion concentration is 1.5 mmol / kg or less, preferably 0.80 mmol / kg or less, and 0.40 mmol / kg or less is more preferable, and it is still more preferable not to contain a sulfate ion. When the sulfate ion concentration is high, the adjustment can be performed by mixing water having a low sulfate ion concentration such as ion-exchanged water to lower the sulfate ion concentration. The step of measuring the sulfate ion concentration of water for preparing the rinse agent α, and the step of preparing the rinse agent α used in the rinsing step (2) so that the sulfate ion falls within the above range based on the measured value. It is preferable to have.

  The rinse agent α is an aqueous composition containing the component (a) and the component (b), and water is used as an aqueous medium. As water, deionized water, ion-exchanged water, tap water, industrial water and the like can be preferably used. From the viewpoint of adjusting the cation concentration Pc and the sulfate ion concentration, water in which the cation concentration Pc and the sulfate ion concentration are in the above ranges is preferable.

The rinse agent α may further contain an antifoaming agent, a chelating agent, a preservative, and the like as long as the effect of the present invention is obtained. However, defoamers, chelating agents, adjusted to cation concentration P _C and sulfate ion concentration of the inorganic salts also contain an antiseptic agent in the rinse agent α is within the range. Moreover, from the viewpoint of water repellency of the steel strip surface, the rinsing agent α preferably has a pH of 3 or more, more preferably 5 or more, still more preferably 6 or more, and preferably 10 or less, more preferably 9 or less. .

  In the rinsing step (2), the rinsing agent α is preferably 50 ° C. or lower, more preferably 40 ° C. or lower, and further preferably 30 ° C. or lower in order to reduce the energy cost required to raise the temperature of the rinse agent. Use. There is no particular lower limit, but it is usually 5 ° C or higher.

  In the rinsing step (2), one or more rinsing treatments can be included, but the rinsing agent α is brought into contact with the steel sheet in the final rinsing treatment before reaching the drying step, and the cleaning step (1) is performed. The steel sheet is treated. When two or more rinse treatments are included, the rinse step (2) can be rinsed with a rinse agent or water other than the rinse agent α, but the final rinse treatment in the rinse step (2) is a rinse agent. It is necessary to use α.

  As a specific example of the rinsing agent treatment using the rinsing agent α performed in the final rinsing process in the rinsing step (2), the steel sheet is rinsed by brushing to rinse the steel sheet, and the above-mentioned without spraying and brushing. Examples of the rinse rinsing treatment include rinsing a steel plate, and rinsing rinsing treatment by immersing the steel plate. Among these, from the viewpoint of causing the rinse agent α to efficiently act on the steel sheet, the immersion rinse treatment and / or the spray rinse treatment are preferable, and the spray rinse treatment in that the rinse agent α can be directly and efficiently acted on the steel plate. Is more preferable. From the viewpoint of reusing the rinse agent α, it is preferable to spray the rinse agent α and introduce the rinse agent α distilled from the steel sheet surface after the spray treatment into the immersion bath and use it for the immersion rinse treatment.

  In the brush rinsing treatment, the rinse agent α is brought into contact with the steel sheet by spraying the rinse agent α on the steel sheet and the brush roll while conveying the steel sheet between the brush rolls or between the brush roll and the transport roll. The rotation speed of the brush roll is preferably 100 revolutions / minute or more, more preferably 500 revolutions / minute or more, and preferably 1200 revolutions / minute or less, more preferably 1000 revolutions / minute or less.

In the spray rinsing treatment, the rinse agent α is directly sprayed on the steel plate, and the rinse agent α is brought into contact with the steel plate. Spray conditions are preferably a spray pressure of 0.05 MPa or more, more preferably 0.1 MPa or more, and preferably 1.5 MPa or less, more preferably 1 MPa or less. Spray volume is preferably at least 1 m ³ / time, more preferably at least 5 m ³ / time, more preferably more than 7m ³ / time, and is preferably 100 m ³ / time or less, more preferably less 70m ³ / time, 60 m ³ / Hour or less is more preferable. The spray time (contact time in the spray rinse treatment) is preferably 0.01 seconds or more, more preferably 0.1 seconds or more, still more preferably 1 second or more, and preferably 30 seconds or less, more preferably 10 seconds or less.

  In the immersion rinse treatment, the immersion time in the rinse agent α is preferably 1 second or more and 5 seconds or less. When showering, the spray pressure is 0.05 MPa or more and 1.5 MPa or less, and 0.1 seconds or more and 5 seconds or less. preferable.

  In the case where the rinse step (2) includes two or more rinse treatments, when the steel sheet is treated with a rinse agent other than water or the rinse agent α, the rinse agent is subjected to a brush rinse treatment with a rinse agent other than water or the rinse agent α. A method of immersion rinse treatment with α and a method of immersion rinse treatment with a rinse agent other than water or rinse agent α and spray rinse treatment with rinse agent α are preferable. From the viewpoint of reducing the load of wastewater treatment, it is more preferable to treat with water and then rinse with α. Specifically, a method of performing a brush rinse treatment with water and performing an immersion rinse treatment with a rinse agent α and a method of performing an immersion rinse treatment with water and a spray rinse treatment with the rinse agent α are more preferable.

  Further, for example, when treating with water or a rinse agent other than the rinse agent α, the temperature of the water used is preferably 5 ° C. or higher, more preferably 10 ° C. or higher, and preferably 40, in order to reduce energy costs. C. or lower, more preferably 30 C or lower. As a method of treating with water, the steel plate may be immersed in water or a rinse agent, and may be rinsed with a shower or the like. When the steel sheet is immersed in water or a rinse agent, the immersion time is preferably 1 second or more and 5 seconds or less, and when showering, the spray pressure is 0.05 MPa or more and 1.5 MPa or less and 0.1 seconds or more and 5 seconds or less. preferable.

  In the brush rinsing process, water or a rinse agent is brought into contact with the steel sheet by spraying the steel sheet and the brush roll while transporting the steel sheet between the brush rolls or between the brush roll and the transport roll. The rotation speed of the brush roll is preferably 100 revolutions / minute or more, more preferably 500 revolutions / minute or more, and preferably 1200 revolutions / minute or less, more preferably 1000 revolutions / minute or less.

In the spray rinsing process, water or a rinse agent is directly sprayed on the steel sheet, and the steel sheet is brought into contact with water or a rinse agent. Spray conditions are preferably a spray pressure of 0.05 MPa or more, more preferably 0.1 MPa or more, and preferably 1.5 MPa or less, more preferably 1 MPa or less. Spray volume is preferably at least 1 m ³ / time, more preferably at least 5 m ³ / time, more preferably more than 7m ³ / time, and is preferably 100 m ³ / time or less, more preferably less 70m ³ / time, 60 m ³ / Hour or less is more preferable. The spray time (contact time in the spray rinse treatment) is preferably 0.01 seconds or more, more preferably 0.1 seconds or more, still more preferably 1 second or more, and preferably 30 seconds or less, more preferably 10 seconds or less.

  In the rinsing step (2), when the steel sheet is immersed in water or a rinse agent, the immersion time of the steel sheet in water or rinse agent is preferably 0.5 seconds or more, more preferably 1 second or more, and 10 Seconds or less are preferable, and 5 seconds or less are more preferable.

  The said washing | cleaning process (1) and the rinse process (2) are normally provided as a continuous line which conveys a steel plate. The conveyance speed of the steel sheet is usually 30 m / min or more, preferably 50 m / min or more, and 1000 m / min or less, preferably 800 m / min or less. In consideration of the conveyance line speed, the cleaning step (1 ) And the rinsing step (2), each processing time is set.

  Further, from the viewpoint of reducing the load in the drying step (3), the surface of the steel sheet treated with the rinse agent using the cleaning agent α is treated between the rinse agent treatment using the cleaning agent α and the drying step (3). It is preferable to perform a process of holding the surface substantially perpendicular to the ground. By this treatment, the amount of water remaining on the surface of the steel sheet is reduced because the water on the surface of the steel sheet to which water repellency is imparted by the cleaning agent α falls due to gravity. From the viewpoint of reducing the amount of water on the steel sheet surface, the time for maintaining substantially vertical is preferably 1 second or more, more preferably 3 seconds or more, and from the viewpoint of transporting the steel sheet, 30 seconds or less is preferable, and 20 seconds. The following is more preferable.

  Further, from the viewpoint of reducing the load in the drying step (3), a gas such as air is sprayed on the surface of the steel plate between the rinse agent treatment using the cleaning agent α and the drying step (3), and moisture on the steel plate. It is preferable to carry out a process of blowing off.

[Drying step (3) for drying the steel sheet after the rinsing step (2) is performed]
In the drying step (3), the rinsing step (2) is performed, and the steel sheet to which the rinse agent α is attached is dried. In the drying step (3), the steel sheet to which the rinsing agent α is adhered is dried in accordance with conventional conditions. As a drying means in the drying step, for example, a method of putting in an oven at 80 ° C. or higher and 150 ° C. or lower, preferably 120 ° C. or lower is given. Moreover, the method of injecting gas, such as air adjusted to these temperatures, to the steel plate surface is mentioned. For example, the drying time is preferably 60 seconds or less, more preferably 40 seconds or less, and even more preferably 20 seconds or less from the viewpoint of reducing the number of heaters in a continuous line that conveys the steel sheet and reducing the energy cost. In a production facility of a steel sheet factory, a method of heating at 80 ° C. or higher and 150 ° C. or lower, preferably 120 ° C. or lower, for 3 to 10 seconds and drying is exemplified.

  The steel plate obtained after washing can be used in various applications such as automotive steel plates, steel plates for beverages such as canned foods, and steel plates for home appliances. The amount of adhesion such as oil stains on the surface of the steel sheet after washing varies depending on the use of the steel sheet, but when the carbon adhesion mass of the steel sheet before washing is 100%, it is preferably 10% or less after washing, preferably 5% or less. It is more preferable that it is 3% or less.

This specification discloses the following manufacturing methods, compositions, or uses further regarding the above-described embodiment.
<1> After washing step (1) for washing the steel plate after cold rolling, rinsing step (2) for the steel plate after the washing step (1), and after the rinsing step (2) The method for producing a steel sheet includes a drying step (3) for drying the steel plate, wherein the rinsing step (2) includes one or more rinse treatments, and the rinse agent α used for the final rinse treatment is represented by the following general formula ( 1):


(Wherein R ¹ represents a hydrocarbon group having 6 to 22 carbon atoms, R ² represents a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms, R ³ and R ⁴ are the same or different, .X indicating the atom or having 1 or more carbon atoms of 3 or less hydrocarbon groups ^-. the component (a) is at least one selected from compounds represented by) indicating an inorganic anion or an organic anion, the following general formula ( 2):
R ⁵ —O— (AO) _m H (2)
(In the formula, R ⁵ is a linear or branched alkyl group or alkenyl group having 8 to 20 carbon atoms, AO is an alkyleneoxy group having 2 to 4 carbon atoms, m is an average added mole number, and 1 or more. And the number of m AOs may be the same or different from each other.) The component (b) is at least one selected from the compounds represented by: The total concentration of the component (b) is 150 mg / kg or less in the rinse agent α, and the cation concentration P _C (mmol / kg) of the inorganic salt of the rinse agent α (P _C = Σ (A × i ) (Wherein A is the concentration of one cation component (mmol / kg), i is the valence of the cation)) is 0.12 mmol / kg or more and 100 mmol / kg or less, and the sulfate ion concentration is 1.5 mmol / Kg of steel plate Production method.
<2> R ¹ has 6 or more carbon atoms, preferably 8 or more, more preferably 12 or more, still more preferably 16 or more, and 22 or less, preferably 18 or less, The method for producing a steel sheet according to <1>, wherein the steel sheet is a branched alkyl group or alkenyl group.
<3> R ² is a hydrogen atom or 1 or more carbon atoms, preferably 6 or more, more preferably 8 or more, still more preferably 12 or more, still more preferably 16 or more, and 22 or less, preferably 18 The method for producing a steel sheet according to <1> or <2> above, which is preferably a linear or branched alkyl group or alkenyl group, more preferably a linear alkyl group or alkenyl group.
<4> The concentration of the component (a) in the rinse agent α is preferably 5 mg / kg or more, more preferably 10 mg / kg or more, still more preferably 20 mg / kg or more, and preferably 148 mg / kg or less. Preferably, it is 145 mg / kg or less, More preferably, it is 120 mg / kg or less, More preferably, it is 110 mg / kg or less, The manufacturing method of the steel plate in any one of said <1>-<3>.
<5> R ⁵ is a linear or branched alkyl or alkenyl group having 8 or more carbon atoms, preferably 10 or more, more preferably 12 or more, and 20 or less, preferably 18 or less. The manufacturing method of the steel plate in any one of said <1>-<4>.
<6> The above m is 1 or more, preferably 3 or more, more preferably 10 or more, and 100 or less, preferably 50 or less, more preferably 40 or less, and further preferably 30 or less. <5> The method for producing a steel sheet according to any one of the above.
<7> The concentration of the component (b) in the rinse agent α is preferably 2 mg / kg or more, more preferably 5 mg / kg or more, and preferably 145 mg / kg or less, more preferably 140 mg / kg or less, Preferably, it is 130 mg / kg or less, More preferably, it is 80 mg / kg or less, More preferably, it is 50 mg / kg or less, The manufacturing method of the steel plate in any one of said <1>-<6>.
<8> The total concentration of the component (a) and the component (b) is 150 mg / kg or less, preferably 100 mg / kg or less, more preferably 60 mg / kg or less in the rinse agent α, <1> The manufacturing method of the steel plate in any one of <7>.
<9> The mass ratio ((a) / (b)) between the component (a) and the component (b) is preferably 0.1 or more, more preferably 1.0 or more, and further preferably 2.0 or more. And the manufacturing method of the steel plate in any one of said <1>-<8> which is preferably 5.0 or less, more preferably 3.0 or less, and still more preferably 2.7 or less.
<10> The cation concentration is 0.12 mmol / kg or more, preferably 0.30 mmol / kg or more, more preferably 0.40 mmol / kg or more, still more preferably 0.55 mmol / kg or more, and 100 mmol / kg or less. Preferably, it is 80 mmol / kg or less, More preferably, it is 55 mmol / kg or less, More preferably, it is 30 mmol / kg or less, More preferably, it is 15 mmol / kg or less, The manufacturing method of the steel plate in any one of <1>-<9> .
<11> The sulfate ion concentration is 1.5 mmol / kg or less, preferably 0.80 mmol / kg or less, more preferably 0.40 mmol / kg or less, further preferably no sulfate ion, <1> to <10 > The manufacturing method of the steel plate in any one.
<12> In the rinsing step (2), the rinse agent α is preferably 5 ° C. or higher, preferably 40 ° C. or lower, and more preferably 30 ° C. or lower, according to any one of <1> to <11>. A method of manufacturing a steel sheet.
<13> The method for producing a steel sheet according to any one of <1> to <12>, wherein the last rinsing process in the rinsing step (2) is a spray rinsing process.
<14> The method for producing a steel sheet according to any one of <1> to <13>, wherein the last rinsing process in the rinsing step (2) is performed after rinsing with water.
<15> Between the last rinse process of the said rinse process (2) and a drying process (3), the process which hold | maintains the surface of a steel plate substantially perpendicular | vertical with respect to the ground is performed <1>-<14> any The manufacturing method of the steel plate of crab.
<16> Furthermore, it has the process of measuring the cation density | concentration of the inorganic salt of the water for preparing the rinse agent (alpha), and the process of preparing the rinse agent (alpha) used by a rinse process (2) based on a measured value, <1 >-<15> The manufacturing method of the steel plate in any one of.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited at all by these Examples.

<Influence of timing of rinsing agent treatment>
(Preparation of detergent)
Sodium hydroxide 2% by mass, sodium gluconate 0.2% by mass, ethylenediaminetetraacetate sodium 0.1% by mass, nonionic surfactant [C ₁₄ H ₂₉ O (EO) ₇ (PO) ₂ (EO) ₇ H] An aqueous solution obtained by adding and mixing 0.023 mass%, sodium polyacrylate 0.025 mass%, and water 97.652 mass% was used as the cleaning agent A.

[Preparation of test water]
Test water was prepared and used in experiments as a model of water containing ions such as industrial water used in steel sheet manufacturing plants. One or more inorganic salts selected from sodium chloride, calcium chloride (dihydrate), magnesium chloride (hexahydrate) and sodium sulfate are added to ion-exchanged water and stirred to dissolve completely. W-1 to W-43 were prepared. Test water W-26 is distilled water itself to which no inorganic salt is added. Tables 1 and 2 show analytical values of the cation concentration and sulfate ion concentration of each test water.

The cation concentration and sulfate ion concentration were measured by the following methods.
(Sodium ion and potassium ion)
The measurement was performed using an atomic absorption method.
Measurement conditions: SpectraAA manufactured by Varian, wavelength: Na 589.0 nm, K766.5 nm, flame acetylene (1.7 L / min) -air (15 L / min), burner height 7.5 mm, integration time 3 seconds (× 3 times) average)
(Calcium ion and magnesium ion)
Measurements were made using ICP emission spectrometry.
Measurement conditions: Optima 5300 DV manufactured by Perkin Elmer, wavelength: Ca 317.933 nm, Mg 285.213 nm, automatic integration time (1 to 5 seconds × 3 times average), high frequency output 1.3 kW, plasma gas 15 L / min auxiliary gas 0.2 L / min min, sheath gas 0.7mL / min
(Sulfate ion)
Measurement was performed using an ion chromatography method.
Measurement conditions: DX320 manufactured by Dionex, Ion Pac AS11-HC and Ion Pac AG11-HC (guard column) manufactured by Dionex, eluent KOH, analysis by gradient elution, flow rate 1.5 mL / min, detector electric conductivity Detector temperature 35 ° C, sample injection volume 25 μL

[Preparation of rinse agents A to C and a]
1 kg of test water W-1 was heated to 80 ° C., and 11.0 mg of a nonionic surfactant [C ₁₈ H ₃₇ O (EO) ₁₅ (PO) ₁₅ H (random addition)] as component (b), As component (a), 5.3 mg of acid (acetic acid) and 23.7 mg of alkylamine (oleylamine) (29.0 mg as oleylamine acetate) were added and dissolved in this order to prepare rinse agent A. Further, rinse agents B to C and a were prepared in the same manner as the rinse agent A except that the addition amounts of the components (a) and (b) were changed so that the concentrations shown in Table 3 were obtained. Then, rinse agents A to C and a adjusted to 25 ° C. were used in the steps shown in Table 4.

<Examples A to C and Comparative Example a>
<Washing process: alkali cleaning>
Cold rolled steel sheet (dirt: iron powder and rolling oil) with a thickness of 70 mm cut to a length of 70 mm and a width of 100 mm is immersed in the cleaning agent A in the alkali cleaning tank (immersion time 2 seconds), and the alkali cleaning tank Pulled up from.

<Washing process: Electrolytic cleaning>
The steel plate subjected to the alkali cleaning step is immersed in the cleaning agent A in an electrolytic cleaning tank, and subjected to electrolytic cleaning (electrolytic time, switching interval between the negative electrode and the positive electrode is 0.4 seconds each, current density is 14 A / dm ² ), It was lifted from the electrolytic cleaning tank.

<Washing process: Brush cleaning>
While spraying the test water W-1 at a spray pressure of 0.2 MPa and a spray amount of 10 ml / second, using a nozzle (spray nozzle 1 / 4MVE11578 manufactured by Ikeuchi Co., Ltd.) Brush cleaning was performed with a brush roll cleaning tester (manufactured by Showa Kogyo Co., Ltd., nylon brush, brush rotation speed 500 rotations / minute, brush reduction 1 mm, steel plate feed rate 60 m / minute).

<Rinsing process: immersion rinse treatment>
The steel plate after the brush cleaning step was immersed in test water W-1 (immersion time: 2 seconds) and pulled up from the water rinse immersion tank.

<Rinse process: spray rinse treatment>
Using a nozzle (spray nozzle 1 / 4MJ100NBW manufactured by Ikeuchi Co., Ltd.), the rinse agent shown in Table 4 was sprayed onto the steel plate at a spray pressure of 0.2 MPa and a spray amount of 33 ml / second for 3 seconds. And it hold | maintained for 5 second so that the surface of the steel plate which processed the rinse agent might become perpendicular | vertical with respect to the ground.

<Drying process>
The steel plate after the rinsing step was put into a dryer (Tokyo Rika Kikai Co., Ltd., blown constant temperature dryer “WFO-401W”) that was made 80 ° C. and dried. At that time, the time until the moisture on the steel sheet surface was dried was visually measured. Table 4 shows the results. In Table 4, it is described as 1 minute or more when not drying in 1 minute, and * when moisture is not already observed at the end of the rinsing process.

<Comparative Example b and Comparative Examples A to C>
The same treatment as in Example A was performed except that the rinse agent shown in Table 4 was used instead of the test water W-1 in the immersion rinse process, and the test water W-1 was used in the spray rinse process.

<Comparative Examples D and E>
The same treatment as in Example A was performed except that the rinse agent shown in Table 4 was used instead of the test water W-1 in the brush cleaning step, and the test water W-1 was used in the spray rinse step.

<Comparative Examples F and G>
The same treatment as in Example A was performed except that the rinse agent shown in Table 4 was used instead of the cleaner A in the electrolytic cleaning step, and the test water W-1 was used in the spray rinse step.

<Comparative Examples H and I>
The same treatment as in Example A was performed except that the rinse agent shown in Table 4 was used instead of the detergent A in the alkali washing step, and the test water W-1 was used in the spray rinsing step.

<Evaluation of steel sheet drying>
The steel sheet after the rinsing process in the drying process was placed in a dryer set at 80 ° C., and the time until the moisture on the steel sheet surface could be visually confirmed was defined as the drying time. The shorter the drying time, the better the drying property. The evaluation results are shown in Table 4. The water wettability of the steel sheet surface after the rinsing step was evaluated by an index (WB: water break) representing the water wettability by area. The measurement of WB was performed by taking a photograph of the steel sheet before the drying step and applying the area of the wetted part to a copy of graph paper (minimum scale 1 mm) on a transparent film. The smaller the value of WB, the better the drying property. Table 4 shows the types of cleaning agents, rinsing agents and water used in each step, and the evaluation results. Since no chemicals or water is used in the drying process, “-” is described.

  From the results in Table 4, the time until drying in the drying step and the moisture content on the steel sheet surface in the rinsing step are reduced by treating the rinse agent with a rinsing agent using water having a specific cation concentration immediately before the drying step. It can be seen that the drying property is improved. Moreover, it turns out that the drying time of a drying process has a correlation with the water break after a rinse process. In addition, when the total concentration of the component (a) and the component (b) in the rinse agent is 200 mg / kg, the drying property is improved even when the treatment with water is performed after the treatment with the rinse agent (Comparative Examples a and b). It can be seen that, when treated with a rinsing agent using water having a specific cation concentration immediately before the drying step, the drying property is improved even if the contents of the component (a) and the component (b) are reduced (Examples A to A). C, Comparative Examples A to C).

<Influence of cation concentration>
<Examples A-1 to A-25, Comparative Examples 1 to 19>
A rinse agent was prepared in the same manner as in Example A except that the test waters W-1 to W-43 were used, and the drying property was evaluated by a water break after the rinsing step. However, in Comparative Example 19, ion exchange water (test water W-26) itself was used as a rinse agent. The evaluation results are shown in Tables 5 and 6.

  From the results of Table 5 and Table 6, it is understood that the drying property of the steel sheet is improved by setting the cation concentration of the inorganic salt of the rinse agent within a certain range.

<Influence of Nonionic Surfactant, Acid, and Alkylamine Acid Salt>
<Examples 1 to 10>

  A rinse agent was prepared in the same manner as in Example A except that it was blended in the test water W-4 so as to have the concentration and composition described in Table 7, and the drying property was evaluated by a water break after the rinsing step. Table 7 shows the evaluation results.

  From the results of Table 7, it can be seen that the nonionic surfactant and the salt of the specific amine are the component (a) and the component (b), whereby the drying property of the steel sheet is improved.

Claims (6)

A cleaning step (1) for cleaning the steel sheet after cold rolling;
Rinsing step (2) after the washing step (1)
A method for producing a steel sheet comprising a drying step (3) for drying the steel plate after the rinsing step (2) has been performed,
The rinse step (2) includes one or more rinse treatments, and the rinse agent α used for the final rinse treatment is represented by the following general formula (1):


(Wherein R ¹ represents a hydrocarbon group having 6 to 22 carbon atoms, R ² represents a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms, R ³ and R ⁴ are the same or different, .X indicating the atom or having 1 or more carbon atoms of 3 or less hydrocarbon groups ^-. the component (a) is at least one selected from compounds represented by) indicating an inorganic anion or an organic anion, the following general formula ( 2):
R ⁵ —O— (AO) _m H (2)
(In the formula, R ⁵ is a linear or branched alkyl group or alkenyl group having 8 to 20 carbon atoms, AO is an alkyleneoxy group having 2 to 4 carbon atoms, m is an average added mole number, and 1 or more. The number of m AOs may be the same or different, and the component (b) is at least one selected from the compounds represented by:
The total concentration of the component (a) and the component (b) is 150 mg / kg or less in the rinse agent α,
Cation concentration P _C (mmol / kg) of inorganic salt of rinse agent α (P _C = Σ (A × i) (where A is the concentration of cation one component (mmol / kg), i is the valence of the cation) )) Is 0.12 mmol / kg or more and 100 mmol / kg or less,
The manufacturing method of a steel plate whose sulfate ion concentration is 1.5 mmol / kg or less.   The method for producing a steel sheet according to claim 1, wherein a mass ratio of the component (a) to the component (b) is 0.1 or more and 5.0 or less in terms of component (a) / component (b).   The manufacturing method of the steel plate of Claim 1 or 2 whose last rinse process of the said rinse process (2) is a spray rinse process.   The manufacturing method of the steel plate in any one of Claims 1-3 which performs the last rinse process of the said rinse process (2) after the rinse process by water.   The process according to any one of claims 1 to 4, wherein a process of holding the surface of the steel sheet substantially perpendicular to the ground is performed between the last rinse process of the rinse process (2) and the drying process (3). A method of manufacturing a steel sheet. Furthermore, it has the process of measuring the cation density | concentration of the inorganic salt of the water for preparing the rinse agent (alpha), and the process of preparing the rinse agent (alpha) used by the rinse process (2) based on a measured value. The manufacturing method of the steel plate in any one of.