JP2960387B2 - Alkaline cleaning composition for steel sheets - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a steel mill and the like.
The present invention relates to an alkaline cleaning composition for a cold-rolled steel sheet, which is used when continuously cleaning a cold-rolled steel sheet (steel strip), particularly when performing electrolytic cleaning.

[0002]

2. Description of the Related Art Degreasing and cleaning of the surface of a steel sheet is necessary as a pretreatment for performing surface treatment such as plating and painting together with pickling.
This is a very important factor that determines the quality of a product. Examples of the dirt adhering to the steel sheet surface include rolling oil (ester such as tallow, fatty acid, mineral oil, etc.) adhering during cold rolling, oil dirt such as rust preventive oil, and solid dirt such as iron powder. Can be Among these, particularly when oil stains remain, they do not gasify and volatilize in the furnace during annealing, remain as carbides on the steel sheet surface, and cause plating, uneven coating, and the like.

[0003] Surfactants have been used to remove oil stains more efficiently. As the surfactant, a nonionic surfactant which is hardly affected by various ions and has a low foaming property is widely used at present. Further, various chelating agents are generally used as a solid ion dispersing agent such as a sequestering agent, a cleaning aid, and iron powder. As a prior art relating to such cleaning of a steel sheet, Japanese Patent Laid-Open No. 55-1415
No. 77, JP-A-5-125571, JP-A-5-320962
And the like. In particular, JP-A-55-141577 discloses an organic chelating agent, a surfactant, an organic sulfur compound and a strong alkaline agent.
A steel detergent is disclosed. However, although this detergent has an effect of improving iron powder removing properties, it has no effect on improving degreasing properties. In addition, there is no difference in performance depending on the type of the surfactant, and the effect itself of the presence or absence of the surfactant is not clear.

In order to obtain a high-concentration alkaline cleaning agent in which detergent components are put together using a nonionic surfactant, the nonionic surfactant is subjected to salting-out action by the high-concentration alkaline agent. Have the problem of separation.
In order to avoid this, conventionally, a method has been adopted in which such a detergent is supplied as a powdery or flake-like solid product, or an alkaline agent and a nonionic surfactant are supplied in two separate states. . Further, JP-A-4-359096 discloses a technique for adding a stabilizer to obtain a uniform liquid composition.

[0005]

The cleaning equipment for a steel sheet is usually designed to continuously wash a steel sheet (steel strip) wound in a coil shape, and is operated at a speed of about 30 to 1100 m / min. Is done. Therefore, the cleaning time of the steel sheet is a very short time of several seconds at the maximum. The cleaning agent for the steel sheet is 0.1 to 3 g / m 2 attached to the surface of the steel sheet in such a short time.
The oil content of item ² must be removed, and very high detergency is required.

[0006] Cleaning is usually performed at a high temperature of about 80 ° C, and heating is performed using steam in order to maintain the temperature at a constant level. However, in order to obtain a clean steel sheet by lowering the cleaning temperature, it is necessary to increase the concentration of the cleaning agent used, increase the cleaning time, and add a physical cleaning method such as brush cleaning. The washing temperature could not be easily lowered. In addition, when the washing temperature is lowered, the hydrolysis reaction of oils and fats, esters, and the like is slowed, so that the washing efficiency is reduced.
Therefore, there is a demand for a cleaning agent that can efficiently perform high-speed cleaning at a low temperature (50 ° C. or lower).

On the other hand, in recent cold rolling of steel sheets,
In order to improve mill cleanliness and productivity, cold rolling oil is being changed from a tallow-based rolling oil to a synthetic ester-based rolling oil that is liquid at room temperature. This synthetic ester-based rolling oil contains various additives having a high viscosity, and the steel sheet to which the rolling oil containing these high-viscosity components adheres cannot be sufficiently removed with a conventional cleaning agent due to insufficient cleaning power. There is a high possibility that defects will occur. In addition, compared to natural fats and oils such as beef tallow and palm oil which have been used as the base of rolling oil, synthetic esters that are recently used are less susceptible to saponification by alkali and do not saponify in a short time. It cannot be completely cleaned with a cleaning agent. More recently, the acid value of the rolling oil has tended to be higher, but since the acid value has increased, a large amount of iron soap has been generated after rolling, and the emulsifiability in the cleaning of the rolling oil has been reduced, so that the detergency has been reduced. The problem has also arisen. For these reasons, the recent steel sheet has a reduced ability to be cleaned, and conventional cleaning agents have not been sufficiently cleaned. From such a viewpoint, a detergent having a high detergency is required.

[0008] Phosphorus compounds, which have been pointed out as a cause of eutrophication and pollution of lake water, and oxyalkylene adducts of alkylphenols having poor biodegradability are considered in consideration of adverse effects on the environment. There is also a need for cleaning agents that are not used.

Further, in the case of obtaining a high-concentration alkaline detergent using a nonionic surfactant, a method of blending the nonionic surfactant in a high-concentration alkaline solution using a solubilizing agent or the like has been adopted. However, in the case of solubilization, the limit of the blending amount of the nonionic surfactant is low, and a solubilizing agent having no effect on cleaning is used.
The problem was that the OD increased.

[0010] One object of the present invention is to solve the problem of the current 80 ° C.
Alkaline detergent composition for cold-rolled steel sheets that does not cause poor cleaning even if the cleaning temperature is lowered from 50 ° C to 50 ° C or less, without requiring the addition of a physical cleaning method or increasing the use concentration or cleaning time. It is to provide. Another object of the present invention is to provide a high-concentration cold liquid having fluidity and excellent workability.
An object of the present invention is to provide an alkaline cleaning composition for a rolled steel sheet.

[0011]

Means for Solving the Problems The present inventors can obtain a sufficiently clean steel sheet even at a low temperature (10 to 50 ° C.) by using the alkaline cleaning composition described below, and this composition The present inventors have found that a small amount of an organic substance is required from the high cleaning performance, and have completed the present invention.

That is, the present invention provides an alkaline agent comprising a compound represented by the general formula (1):

[0013]

Embedded image

(Wherein, R is a linear or branched alkyl or alkenyl group having 4 to 14 carbon atoms, n is the average number of moles of oxyethylene group, and m is the average number of moles of oxypropylene group). , 0 ≦ n ≦ 20, 0 <m ≦ 20, and α calculated by the following equation α = 0.33 × n−0.15 × m−0.475 × (carbon number of R) +2.6 is −2.0 <α <1.9. to include at least one polyoxyalkylene alkyl ether showing a meet) is intended to provide a cold rolled steel sheet for an alkaline detergent composition according to claim.

The present invention further provides the following formula (2) in addition to the above.

[0016]

Embedded image

(Wherein, R _{1 to} R ₆ are a hydrogen atom and have 1 to 1 carbon atoms)
5 alkyl groups, C1-5 alkoxyl groups, CO
OM or OH, where M is a hydrogen atom, an alkali metal,
It is an alkylamine having 1 to 4 carbon atoms or an alkanolamine having 1 to 6 carbon atoms, and s / t (copolymerization molar ratio) is 0.
/ 10 to 10/1, and the weight average molecular weight (MW) is 1000 to
The present invention also provides an alkaline detergent composition for cold-rolled steel sheets, comprising at least one water-soluble high molecular carboxylic acid having a structure represented by the following formula: The composition is fluid in a liquid or slurry state even at a high concentration, and is stable without separation. Also high concentration cold pressure
When the alkali cleaning composition for rolled steel sheets is diluted and used for cleaning steel sheets, it is possible to sufficiently soften water even when using water having high hardness such as industrial water. That is, the water-soluble polymer carboxylic acids used in the present invention contribute to stability during storage and contribute to softening as a chelating agent during washing. In this case, the action that contributes to stability is not solubilization, but slurrying by precipitation of the water-soluble polymer carboxylic acid, but some of them have solubilizing ability depending on the structure.

Further, the alkaline detergent composition for a cold-rolled steel sheet of the present invention can contain aldonic acids. When an aldonic acid is contained, there is an advantage that the washing performance is synergistically improved by combination with the polyoxyalkylene alkyl ether of the general formula (1).

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An aerial for a cold rolled steel sheet according to the present invention will be described below.
Lucari detergent composition (hereinafter referred to as “alkali detergent group for steel sheets”
The composition will be described in detail. As the alkali agent used in the present invention, any water-soluble alkali agent can be used. As a specific example,
Alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, sodium orthosilicate, sodium metasilicate, sodium sesquisilicate, sodium silicate No. 1, sodium silicate No. 2, sodium silicate No. 3, sodium phosphate Phosphates such as sodium hydrogen, disodium hydrogen phosphate and trisodium phosphate; carbonates such as disodium carbonate, sodium hydrogen carbonate, dipotassium carbonate and potassium hydrogen carbonate; borates such as sodium borate and the like. Can be Two or more water-soluble alkali agents may be combined. Preferred are sodium hydroxide, potassium hydroxide, sodium orthosilicate and sodium metasilicate, and more preferred are sodium hydroxide and potassium hydroxide.

The polyoxyalkylene alkyl ether used in the present invention is represented by the above general formula (1). R in the formula is a linear or branched alkyl group or alkenyl group having 4 to 14 carbon atoms, and more preferably R is 6 to 10 carbon atoms, and more preferably R is carbon atom. Equations 8 to 14 n represents the average number of added moles of the oxyethylene group, m represents the average number of added moles of the oxypropylene group, 0 ≦ n ≦ 20, 0 <m ≦ 20, and α represented by the above formula is −2.0 < It satisfies α <1.9. α is an index that defines a compound that contributes to an extremely excellent degreasing effect in the general formula (1) by R, n, and m.
The addition form of oxyethylene and oxypropylene may be block or random, and in the case of a block, the positions of oxyethylene and oxypropylene may be reversed. However, those obtained by block addition in the order of oxypropylene-oxyethylene are more preferable.

Preferably, the polyoxyalkylene alkyl ether of the general formula (1) according to the present invention has an average molecular weight.
It is 130-1000, more preferably 130-700. Preferred values of the average number of moles of the oxyethylene group and the oxypropylene group are 0 ≦ n <8 and 0 <m <5;
It is more preferable that <n <8. More preferably, the value of α is -1.3 <α <1.6 in the case of a straight chain;
More preferably, -1.3 <α <0.7, particularly preferably -0.8 <α <0.7, and most preferably -0.3 <α <.
0.3. In the case of a branched chain, more preferred is -2.0 <α
<1.6, more preferably -2.0 <α <1.0, and most preferably -2.0 <α <0.3.

The water-soluble high-molecular carboxylic acids used in the present invention are those represented by the above general formula (2). R _{1 to} R ₆ in the formula are any of hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkoxyl group having 1 to 5 carbon atoms, COOM, and OH, and all may be the same or different. Although both terminals of the general formula (2) are not particularly limited,
Hydrogen atom, OH, alkyl group having 1 to 5 carbon atoms, 1 carbon atom
To 5 alkoxyl groups or SO ₃ M, which may be the same or different. M is any of hydrogen, an alkali metal, an alkylamine having 1 to 4 carbon atoms, and an alkanolamine having 1 to 6 carbon atoms. s and t each indicate the number of moles of the monomer in parentheses, and s may be 0. When s is 0, the monomer is a homopolymer of a monomer represented by the number of moles t. The copolymerization molar ratio s / t of s and t is 0.
/ 10 to 10/1 and a weight average molecular weight (MW) of 1,000
~ 100,000, preferably 3,000-50,000, more preferably
5,000-20,000. The polymerization form may be block or random. Specific examples include acrylic acid homopolymers, acrylic acid-maleic acid copolymers, α-hydroxyacrylic acid homopolymers, C5 olefin-maleic acid copolymers, isobutylene-maleic acid copolymers, and the like. Salts or amine salts. Preferably acrylic acid homopolymer, acrylic acid-
It is a maleic acid copolymer. Specific product names include
Kao Corporation Poise 540, Poise 530, Poise 521, Poise 520, Nippon Peroxide Co., Ltd. Pale Plaque 250, Pale Plaque 1200, Pale Plaque 5000, Nippon Zeon Co., Ltd.Quinflow 540, Quinflow 54
2, Quinflow 543, Quinflow 560, Quinflow 6
40, Quinflow 750, Alon T-40 manufactured by Toagosei Co., Ltd.
(M), Kuraray Co., Ltd. Isoban 06, Isoban 04, Isoban 600, Nippon Shokubai Co., Ltd. Aquaric DL100. Two or more water-soluble polymer carboxylic acids may be combined.

The aldonic acids used in the present invention are monosaccharides having a carboxyl group and alkali metal salts or amine salts thereof. Specific examples include glyceric acid, tetronic acid, pentonic acid, hexonic acid, heptonic acid and the like, and alkali metal salts or amine salts thereof. Preferred are gluconic acid, glucoheptonic acid and the like, and alkali metal salts or amine salts thereof, and more preferably sodium gluconate or sodium glucoheptonate. Aldonic acids can also be used in combination of two or more.

Although water is used as the medium of the composition of the present invention, it is preferably deionized water.

Next, the content of the composition of the present invention will be described. The content of the alkali agent in the composition is 0.5 to 48.0% by weight.
Is preferred. At the time of cleaning the steel sheet, it is preferably 0.5 to 10.0% by weight, more preferably 1.0 to 8.0% by weight. If the amount is less than 0.5% by weight at the time of cleaning the steel sheet, the cleaning performance is poor, and if it exceeds 10.0% by weight, the cleaning performance tends to be saturated, but it is economically disadvantageous. Particularly preferably, sodium hydroxide is used in an amount of 1.0 to 8.0% by weight at the time of cleaning the steel sheet. In the selection and blending of the alkaline agent, the pH at the time of cleaning the steel sheet is considered from the viewpoints of cleanability and electrical conductivity.
It is desirable to keep the range over 12.5.

The compounding amount of the polyoxyalkylene alkyl ether in the composition of the present invention is preferably 0.05 to 30.0% by weight. When the steel sheet is washed, the content is preferably 0.05 to 5.0% by weight, more preferably 0.1 to 3.0% by weight. 0.05% when cleaning steel sheet
If it is less than 5% by weight, the washing performance is inferior. If it exceeds 5.0% by weight, the washing performance tends to be saturated, but the COD increases, which is economically disadvantageous.

The amount of the water-soluble high molecular carboxylic acid to be added to the composition of the present invention is preferably 0 to 10.0% by weight. 0.05 to 1.0% by weight at the time of cleaning the steel sheet, more preferably
0.1 to 0.5% by weight. When the steel sheet is washed at less than 0.05% by weight, water cannot be sufficiently softened when using water having a high hardness such as industrial water, and calcium ions and magnesium ions are mixed with fatty acids and water-insoluble salts mixed as dirt. It is more likely to cause poor cleaning. Also,
Even if it is added in excess of 1.0% by weight, the water softening ability becomes saturated, but the COD increases, which is economically disadvantageous.

The aldonic acid is preferably incorporated in the composition of the present invention in an amount of 0.03 to 20.0% by weight. At the time of cleaning the steel sheet, the content is preferably 0.03 to 3.0% by weight, more preferably 0.05 to 2.0% by weight. If the amount is less than 0.03% by weight at the time of cleaning the steel sheet, the cleaning performance is poor, and if the content exceeds 3.0% by weight, the cleaning performance is saturated, but the COD increases and it is economically disadvantageous. In the case of sodium gluconate and sodium glucoheptonate, good detergency can be obtained even at 0.05 to 1.0% by weight.

When the composition of the present invention is used for cleaning a steel sheet,
Each component may be pre-mixed in one or two liquids and diluted with water before use in the washing tank, or each component may be separately charged into the washing tank and diluted with water. Absent.

Next, the amount of the high-concentration alkaline cleaning composition suitable for storage according to the present invention (this is referred to as a high-concentration alkaline cleaning composition) will be described. First, the amount of the alkaline agent is preferably 20.0 to 48.0% by weight during storage,
More preferably, it is 30.0 to 45.0% by weight. 20.0 when stored
When the amount is less than 4% by weight, the precipitation amount of the water-soluble polymer carboxylic acids is small, and the stability cannot be maintained as a slurry, resulting in poor stability. When the amount exceeds 48.0% by weight, the viscosity of the detergent becomes too high, which is not desirable. Particularly preferably, sodium hydroxide is used in a storage amount of 33.0 to 42.0% by weight during storage.

The amount of the polyoxyalkylene alkyl ether to be added to the high-concentration alkaline detergent composition of the present invention during storage is preferably 0.1 to 30.0% by weight, more preferably 0.2 to 20.0% by weight, and still more preferably 0.5 to 20.0% by weight. %. If it is less than 0.1% by weight during storage, the necessary concentration of polyoxyalkylene alkyl ether at the time of cleaning the steel sheet cannot be obtained. Further, since this composition is stabilized in a slurry state, if the polyoxyalkylene alkyl ether having a low specific gravity is too much, it is easily separated, and if added in excess of 30.0% by weight during storage, the product stability is poor.

The amount of the water-soluble high-molecular carboxylic acid to be added to the high-concentration alkaline detergent composition of the present invention is preferably 0.5 to 10.0% by weight during storage, more preferably 1.0 to 8.0%.
% By weight. If it is less than 0.5% by weight at the time of storage, the product stability is poor, and if it exceeds 10.0% by weight, the viscosity of the detergent becomes too high and it becomes difficult to transport the detergent through piping. Particularly preferably, acrylic acid homopolymer (MW: 5,000 to 20,
000), acrylic acid-maleic acid copolymer (MW: 5,000
20,000) and / or 1.0 to 6.0 of these sodium salts.
It is used in a weight% amount.

The amount of the aldonic acid to be added to the high-concentration alkaline detergent composition of the present invention is preferably 0.1 at the time of storage.
It is from 0.05 to 20.0% by weight, more preferably from 0.1 to 15.0% by weight, and still more preferably from 0.5 to 15.0% by weight. 0.05 when stored
If the content is less than the weight percentage, the concentration of aldonic acids necessary for washing the steel sheet cannot be obtained. Also, if it is added in excess of 20.0% by weight during storage, the amount of water required to dissolve aldonic acid will increase, and the necessary amount of alkali agent and water-soluble polymer carboxylic acid required for product stabilization can be added. Disappears.

The alkaline detergent composition for steel sheets of the present invention comprises:
It is effective when washing at a high speed of 500 m / min or more, and more effective when washing at a high speed of 800 m / min or more. In particular, it is effective when cleaning cold-rolled steel sheets at a high speed of 1 second or less, which is required for electrolytic cleaning. General steel plate cleaning line is immersion cleaning → brush cleaning →
The structure is as follows: electrolytic cleaning → brush cleaning → rinsing → drying, but it takes about 50 m from immersion cleaning to drying, and when the line speed is 500 m / min, cleaning is performed in a very short time of 6 seconds in all processes. Will be Among them, the electrolytic cleaning process
When the line speed is 500 m / min, the calculation is about 1.2 to 2.4 seconds. The alkaline cleaning composition for steel sheets of the present invention is effective for such a short and even shorter time electrolytic cleaning, and thereby allows to increase the cleaning line speed.

The alkaline detergent composition for steel sheets of the present invention is effective for steel sheets to which a rolling oil containing 50% by weight or more of synthetic ester is adhered, and that the synthetic ester is 70% or less.
It is more effective for a steel sheet to which rolling oil containing at least% by weight adheres. As the synthetic ester, somaric acid, oleic acid, linoleic acid, gadolinic acid, a synthetic ester of a higher aliphatic unsaturated acid having 16 to 20 carbon atoms such as dimer acid or polymer acid such as tall oil fatty acid, propylene glycol, Polyhydric alcohols such as ethylene glycol, diethylene glycol, neopentyl glycol, butanediol, pentanediol, polyoxyethylene glycol, polyoxypropylene glycol, trimethylolpropane, pentaerythritol, glycerin and aliphatic carboxylic acids having 6 to 22 carbon atoms. A synthetic ester as a raw material, a synthetic ester using a C1-C12 aliphatic alcohol and a C6-C22 aliphatic carboxylic acid as a raw material,
Synthetic esters made from polyhydric alcohols and aliphatic hydroxycarboxylic acids having 6 to 22 carbon atoms, polybasic acids such as adipic acid, sebacic acid, azelaic acid, phthalic acid, trimellitic acid, pyromellitic acid, and 1 carbon atom And synthetic esters obtained from aliphatic alcohols of the above-mentioned formulas, and esters of the above-mentioned alcohols with ethylene oxide, propylene oxide and butylene oxide adducts.

Furthermore, the alkaline detergent composition for steel sheets of the present invention is effective for steel sheets to which rolling oil having an acid value of 10 KOH mg / g or more adheres, and has an acid value of 20 KOH mg / g.
/ G or more is more effective for a steel sheet to which a rolling oil adheres.

The alkaline detergent composition for steel sheets of the present invention comprises:
Contains at least 50% by weight of synthetic ester and has an acid value of 10 KO
It is particularly effective for a steel sheet to which a rolling oil of Hmg / g or more adheres.

The alkaline detergent composition for a steel sheet of the present invention is effective for a steel sheet to which a rolling oil containing at least 10% by weight of a high-viscosity ester adheres, and at least 20% by weight of a high-viscosity ester. It is more effective for steel sheets to which the contained rolling oil adheres. In particular, the viscosity of high viscosity esters is 40
It is effective for a steel sheet having a rolling oil of 70 mm ² / s or more at 100 ° C., preferably 100 mm ² / s or more, more preferably 150 mm ² / s or more. As a high viscosity ester,
Zomaric acid, oleic acid, linoleic acid, gadolinic acid, synthetic esters derived from dimer acids or polymer acids of higher aliphatic unsaturated acids having 16 to 20 carbon atoms such as tall oil fatty acids, propylene glycol, ethylene glycol, diethylene glycol, Polyhydric alcohols such as neopentyl glycol, butanediol, pentanediol, polyoxyethylene glycol, polyoxypropylene glycol, trimethylolpropane, pentaerythritol, glycerin and aliphatic alcohols having 6 to 22 carbon atoms And synthetic esters using a polyhydric alcohol and an aliphatic hydroxycarboxylic acid having 6 to 22 carbon atoms as raw materials. Although not an ester, the alkaline detergent composition for steel sheets of the present invention is also effective for high-viscosity compounds such as polybutene.

The alkaline detergent composition for steel sheets of the present invention further comprises a polymer of a higher aliphatic unsaturated acid having 16 to 20 carbon atoms.
It is effective for a steel sheet to which rolling oil containing at least% by weight adheres. As a polymer of a higher aliphatic unsaturated acid,
Examples include dimer acids and polymer acids of higher aliphatic unsaturated acids having 16 to 20 carbon atoms such as zomaric acid, oleic acid, linoleic acid, gadolinic acid and tall oil fatty acid.

The alkaline detergent composition for steel sheets of the present invention comprises:
Although the steel sheet can be sufficiently cleaned even if the cleaning temperature is lowered to 10 to 50 ° C., if the cleaning is performed at a temperature higher than 50 ° C., the cleanliness becomes higher.

Further, the alkali detergent composition for steel sheets of the present invention generally used organic builders for improving the detergency, for example, nitrilotriacetic acid, ethylenediaminetetraacetic acid, ethylenediaminediacetic acid, tetraethylenetetraminehexaacetic acid. It is also possible to mix an aminocarboxylic acid such as an alkali metal salt or a lower amine salt, etc., in consideration of an increase in COD and cost.

The alkaline detergent composition for steel sheets of the present invention may further comprise a surfactant generally used for improving detergency, such as a nonionic surfactant, an anionic surfactant, or an amphoteric surfactant. Surfactants and the like can be blended in consideration of the increase in COD and cost.

The alkaline detergent composition for steel sheets of the present invention comprises:
It exerts its effects in continuous cleaning of steel sheets (steel strips) in steel mills, that is, immersion cleaning, spray cleaning, brush cleaning, electrolytic cleaning, etc., but it is particularly effective when used when electrolytically cleaning cold-rolled steel sheets at low temperatures. large.

[0044]

EXAMPLES Preparation of Steel Sheets to be Washed All steel sheets to be washed were prepared by the following procedure. That is, the components shown in Table 1 below were blended in the amounts shown in Table 2, the steel sheet was cold-rolled using the prepared rolling oil, and cut into 25 mm × 50 mm pieces.

[0045]

[Table 1]

[0046]

[Table 2]

Detergent Composition The composition of the detergent is shown in each table or in the description of the table below. The balance is deionized water. The washing was performed at 40 ° C. unless otherwise specified.

Cleaning Test Procedure All cleaning tests were performed in the following procedure. That is, the steel plate to be cleaned is immersed in the cleaning solution for 1 second, and then the current density is continuously 10 A / dm.
^{In step 2} , the potential of the steel sheet is switched from negative to positive once for 0.5 seconds each, electrolytically washed, rinsed with water, and then dried.

Measurement Method of Residual Adhered Oil Content The amount of adhering oil on the surface of the steel sheet after the cleaning test was all measured using a steel sheet adhering oil amount measuring device EMIA-111 (manufactured by Horiba, Ltd.). The measured value is an average of five measurements. As a criterion for determining the detergency, the residual surface oil content of 40 mg / m ² or more is poor, 20 mg / m ² or more and less than 40 mg / m ² is good, 10 mg / m ² or more and less than 20 mg / m ² is excellent, and 10 mg / m ² is good. m less than ² was Tokuyu.

Product stability The stability was evaluated by observing the time-dependent changes in the state of the high-concentration alkaline detergent composition for steel sheets during storage at room temperature. The symbol X indicates that the sample was not homogenized or separated in one day, and the symbol ○ indicates that the sample was uniform without separating in one day.

The results of the cleaning test and the product stabilization test under the above conditions are shown in Tables 3 to 14. In addition, the polyoxyalkylene alkyl ethers in Table 6 and subsequent tables are indicated by using the abbreviations used in Tables 4 and 5, and the water-soluble high molecular carboxylic acids in Table 9 and thereafter are indicated by using the abbreviations used in Table 8. .

[0052]

[Table 3]

[0053]

[Table 4]

[0054]

[Table 5]

[0055]

[Table 6]

[0056]

[Table 7]

[0057]

[Table 8]

[0058]

[Table 9]

[0059]

[Table 10]

[0060]

[Table 11]

[0061]

[Table 12]

[0062]

[Table 13]

[0063]

[Table 14]

First, Table 3 compares the cleaning properties of different rolling oils using sodium hydroxide at a concentration of 2.0% by weight as the alkali agent and the cleaning agents shown in Table 3 as Examples and Comparative Examples. The results are shown. Although the evaluation of the detergency of the composition of the present invention is all good even at a low temperature, it is understood that sufficient detergency cannot be obtained when the temperature is lowered in Comparative Examples.

Tables 4 and 5 show that sodium hydroxide was used as an alkali agent at a concentration of 2.0% by weight, and the compounds shown in these tables were used as examples and comparative examples, respectively. The result of having compared the difference of the detergency based on the change of the carbon number of a group, the addition mole number of oxyethylene and oxypropylene, and the value of (alpha) is shown. The same steel plate as the steel plate No. 20 in Table 2 was used as the steel plate to be cleaned. From these results, in all ranges within the range specified by the present invention, good detergency is obtained even at a low temperature, whereas out of the specified range, that is, in the case of Comparative Example, good detergency is obtained at a high temperature. In some cases, however, it was found that all of the samples were defective under low temperature conditions, and that a large effect could not be obtained even if the concentration was increased.

Table 6 shows that sodium hydroxide was used as the alkaline agent.
Used at a concentration of 2.0% by weight.
20 shows the results of comparison of the effect of the concentration of polyoxyalkylene alkyl ether on detergency when the same o.20 was used. From Table 6, it can be seen that the composition of the present invention has good detergency. In addition, when the addition amount is 15% by weight or 20% by weight, the detergency increases, but the tendency of saturation is observed.

Table 7 shows the steel sheet No. 2 in Table 2 as the steel sheet to be cleaned.
The results of comparison of detergency with respect to the type and concentration of an alkali agent and / or aldonic acids using the same as those of 0 are shown. As is clear from Table 7, the composition of the present invention has good detergency, and the addition of aldonic acids further improves the detergency.

Table 8 shows that sodium hydroxide (40.0% by weight) was used as an alkali agent, EP-9 (4.0% by weight) in Table 5 was used as a polyoxyalkylene alkyl ether, and various water-soluble high molecular carboxylic acids were used in an amount of 2.0% by weight. 3 shows the results of evaluating product stability of a high-concentration alkaline cleaning composition in which the composition was blended at a high concentration. In addition, both ends of the water-soluble high molecular carboxylic acids are all OH, and the balance amount is deionized water. As can be seen from these tables, the compositions of the present invention are stable. The molecular weight in the table indicates a weight average molecular weight, and was measured by gel permeation chromatography (GPC) using polyethylene glycol as a standard.

Tables 9 and 10 show that sodium hydroxide was used at a concentration of 34.0% by weight as an alkaline agent, WPC-3 of Table 8 was used at a concentration of 4.0% by weight as a water-soluble polymer carboxylic acid, The result of having compared the washing | cleaning property about the high concentration alkali cleaning composition which mix | blended oxyalkylene alkyl ether is shown. The cleaning test was performed by using the same steel plate as the steel plate No. 20 in Table 2 as the steel plate to be cleaned, and diluting the composition shown in the table 17 times with water. As is clear from these tables, the compositions of the present invention were all evaluated for detergency, but were unsatisfactory outside the specified range (Table 9). Further, all the compositions of the present invention exhibited good (○) stability.

Table 11 shows that high-concentration alkaline detergent was prepared by using sodium hydroxide at a concentration of 35.0% by weight as an alkaline agent and using WPC-4 of Table 8 at a concentration of 2.5% by weight as a water-soluble high molecular carboxylic acid. The result of having compared the influence of the density | concentration of polyoxyalkylene alkyl ether on detergency in the case of making a composition is shown. The cleaning test was performed using the same steel plate as the steel plate No. 20 in Table 2 as the steel plate to be cleaned, and diluting the composition shown in the table 10 times with water. As is clear from these tables, the composition of the present invention has good detergency. Further, all the compositions of the present invention exhibited good (○) stability.

Tables 12 and 13 show the results of comparing the detergency and product stability of the high-concentration alkaline detergent composition by changing the type and concentration of the alkaline agent and aldonic acid, respectively. The cleaning test was performed using the steel sheet No. 20 in Table 2 as the steel sheet to be cleaned.
Using the same composition as described above, the composition shown in the table was diluted 20 times with water. As is clear from these tables, the composition of the present invention has good detergency and is stable. Further, when Table 12 and Table 13 are compared, it can be seen that the detergency is further improved by including aldonic acids.

Table 14 shows that various high-concentration alkaline cleaning compositions using sodium hydroxide (40.0% by weight) as an alkaline agent and EP-9 (4.0% by weight) of Table 5 as a polyoxyalkylene alkyl ether were prepared. 3 shows the results of comparing the product stability by changing the type and concentration of the water-soluble polymer carboxylic acids. Table 14 shows that the composition of the present invention is stable. In particular, the amount added is 0.5 to 10.
Good results have been obtained in the range of 0 wt%. The stability is good even when the concentration of the water-soluble high molecular carboxylic acid is 12.0 wt%, but the fluidity is low due to the high viscosity, so that the transportability is poor.

[0073]

The alkaline detergent composition for steel sheets of the present invention has an extremely excellent degreasing effect, so that only a small amount of organic substances is required and the washing temperature can be lowered.
Thereby, the steel plate manufacturing cost can be reduced.
In addition, since the alkaline detergent composition for steel sheets containing the water-soluble polymer carboxylic acids of the present invention is a fluid and stable detergent even at a high concentration, the detergent concentration can be easily controlled and stable operation is possible. become.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ identification code FI C23G 1/14 C23G 1/14 5/032 5/032 (58) Investigated field (Int.Cl. ⁶ , DB name) C23G 1 / 19

Claims (9)

(57) [Claims] An alkali agent and a compound represented by the general formula (1): (Wherein, R is a linear or branched alkyl or alkenyl group having 4 to 14 carbon atoms, n is the average number of moles of oxyethylene group, m is the average number of moles of oxypropylene group, and 0 ≦ n ≦ 20, 0 <m ≦ 20, and α calculated by the following equation α = 0.33 × n−0.15 × m−0.475 × (carbon number of R) +2.6 satisfies −2.0 <α <1.9. An alkali detergent composition for cold-rolled steel sheets, comprising at least one of the following polyoxyalkylene alkyl ethers: 2. Further, the following formula (2): (Wherein, R _{1 to} R ₆ are a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxyl group having 1 to 5 carbon atoms, COOM, or O
H is H, M is a hydrogen atom, an alkali metal, and has 1 to 4 carbon atoms.
Or an alkanolamine having 1 to 6 carbon atoms, and s / t (copolymerization molar ratio) is 0/10 to 10/1.
Wherein the weight-average molecular weight (MW) is at least 1000 to 100,000), and at least one kind of water-soluble high molecular carboxylic acids having a structure represented by the formula: The alkaline detergent composition for a cold-rolled steel sheet according to claim 1. 3. The compounding amount of the alkaline agent is 0.5-48.0% by weight, the compounding amount of the polyoxyalkylene alkyl ether is 0.05-30.0% by weight, and the compounding amount of the water-soluble polymer carboxylic acid is 0-10.0% by weight. The method according to claim 1, wherein
An alkaline cleaning composition for cold-rolled steel sheets. 4. The method according to claim 1, wherein at least one aldonic acid is used.
4. The cold according to claim 1, comprising 0.03 to 20% by weight.
An alkaline cleaning composition for rolled steel sheets. 5. The method according to claim 1, which is used for cleaning a steel sheet containing at least one kind of synthetic ester in an amount of 50% by weight or more and / or having a rolling oil having an acid value of 10 KOH mg / g or more. 4. The alkaline detergent composition for a cold-rolled steel sheet according to any one of 4. 6. A highly viscous material having a viscosity of at least 70 mm ² / s at 40 ° C.
The alkaline detergent composition for a cold-rolled steel sheet according to any one of claims 1 to 5, which is used for cleaning a steel sheet to which a rolling oil containing at least one kind of ester is added in an amount of 10% by weight or more. 7. A steel sheet to which a rolling oil containing at least one polymer of a higher aliphatic unsaturated acid having 16 to 20 carbon atoms in an amount of 1% by weight or more is used for cleaning a steel sheet. The alkaline cleaning composition for cold-rolled steel sheets according to any one of 1 to 6. 8. The alkaline cleaning composition for a cold-rolled steel sheet according to claim 1, which is used for cleaning at a high speed of 500 m / min or more at a line speed. 9. The alkaline cleaning composition for a cold-rolled steel sheet according to claim 1, which is used for electrolytic cleaning of a cold-rolled steel sheet.