JPH10280179A - Alkaline detergent composition for steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a detergent compsn. with which a sufficiently clean steel sheed is obtd. even in a low temp. and which dispenses with addition of org. matter in a lesser amt. from the high level of washing performance and has a flow property in spite of a high concn. by incorporating an alkaline agent and polyoxyethylene alkyl ethers into this compsn. SOLUTION: This detergent compsn. is prepd. by incorporating the alkaline agent and >=1 kinds of the polyoxyethylene alkyl ethers expressed by the general formula: R-O-(CH2 CH2 O)n . In the formula, R is a 5 to 12C straight chain or branched chain alkyl or alkenyl, (n) denotes the average addition molar number of an oxyethylene group, 1 to 20 when R is 5 to 10C and 6 to 20 when 11 to 12C. Further, water-soluble high-polymer carboxylic acids or aldonic acids may be incorporated therein s well. The washing temp. may be lowered down to 10 to 50 deg.C and the org. matter which is the cause for the eutrophication and contamination of lakes and ponds is necessitated to be added in the lesser amt. by such compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an alkaline cleaning composition for steel sheets, which is used when steel sheets (steel strips) are continuously washed at an ironworks or the like, particularly when electrolytic cleaning is performed.

[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 esters such as tallow adhering during cold rolling, rolling oils such as fatty acids and mineral oils, oil stains such as rust-preventive oils, and solid stains such as iron powder. .
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 plate, Japanese Patent Application Laid-Open No.
No. 68, and the like. On the other hand, when a nonionic surfactant is used to obtain a high-concentration alkaline cleaning agent in which detergent components are put together, the nonionic surfactant is formed by the salting-out action of the high-concentration alkaline agent. There is a 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 solubilizing agent or a stabilizing agent to obtain a uniform liquid composition.

[0004]

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. Washing is usually performed at a high temperature of about 80 ° C., and heating is performed using steam to keep the temperature constant. However, reduction in steam cost due to lowering of the washing temperature is demanded. However, in order to obtain a clean steel sheet by lowering the cleaning temperature, the use concentration of the cleaning agent is increased, the cleaning time is lengthened, and a physical cleaning method such as brush cleaning is added as described above. And 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. Generally, the following formulation is applied to the synthetic ester rolling oil in order to improve lubricity. That is, addition of a complex ester for improving boundary lubrication, addition of a viscosity index improver such as polybutene, addition of a polymerized fatty acid (polymerized fatty acid) as an oiliness improver, and an increase in the blending amount of a higher fatty acid. However, such a steel sheet to which a rolling oil containing a high-viscosity component has adhered cannot be completely removed with a conventional cleaning agent due to insufficient cleaning power, and there is a high possibility that defective cleaning will occur. This is presumably because even if the viscosity of the rolling oil is reduced by adding a low-viscosity component, a high-viscosity component having poor fluidity remains selectively. In addition, compared to natural fats and oils such as tallow and palm oil which have been used as the base of rolling oil, synthetic esters that have recently been used are less susceptible to saponification by alkali and do not saponify to sodium soap in a short time. However, conventional cleaning agents cannot completely clean. 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.

[0006] Further, 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, when a high-concentration alkaline cleaning agent is to be obtained using a nonionic surfactant, a nonionic surfactant is blended into a high-concentration alkaline solution using a solubilizing agent or the like to form a single solution. However, in the case of solubilization, the limit of the amount of the nonionic surfactant is low, and the use of a solubilizer that has no effect on cleaning is accompanied by an increase in COD. The point was the problem.

One object of the present invention is to reduce the current cleaning temperature of 80 ° C. to a cleaning temperature of 50 ° C. or less without adding a physical cleaning method, increasing the use concentration or the cleaning time, An object of the present invention is to provide an alkaline cleaning composition for steel sheets that does not cause poor cleaning. Another object of the present invention is to provide a high-concentration alkaline cleaning composition for steel sheets which has fluidity and excellent workability.

[0009]

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 relates to an alkali agent and a compound represented by the following general formula (1): R—O— (CH ₂ CH ₂ O) nH (1) (wherein R is a straight or branched chain having 5 to 12 carbon atoms) N represents an average number of moles of oxyethylene group added. When R has 5 to 10 carbon atoms, n represents 1
-20, when R has 11-12 carbons, n is 6-20)
And at least one of the following polyoxyethylene alkyl ethers. According to the cleaning composition of the present invention, the use of a specific polyoxyethylene alkyl ether enables low-temperature cleaning of a steel sheet, but this is not described in the above-mentioned prior art patent at all.

The present invention also relates to an alkali agent and a compound represented by the following general formula (1): R--O-(CH ₂ CH ₂ O) nH (1) wherein R is a straight or branched chain having 5 to 12 carbon atoms. An alkyl group or an alkenyl group, and n represents an average number of moles of the added oxyethylene group. When R has 5 to 10 carbon atoms, n is 1
-20, when R has 11-12 carbons, n is 6-20)
And at least one polyoxyethylene alkyl ether represented by the following formula (2)

[0012]

Embedded image

(Wherein, R _{1 to} R _{6 are} hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkoxyl group having 1 to 5 carbon atoms, COO
M or OH M: hydrogen, alkali metal, alkylamine having 1 to 4 carbon atoms, or alkanolamine having 1 to 6 carbon atoms m / n (copolymerization molar ratio): 0/10 to 10/1 weight average molecular weight ( MW): 1,000 to 100,000). The present invention also provides an alkaline cleaning composition for steel sheets, characterized by containing at least one water-soluble polymer carboxylic acid represented by the following formula: The composition is fluid at high concentrations in liquid or slurry form and is stable without separation. Further, when a high-concentration alkaline cleaning composition for steel sheets is diluted and used for cleaning steel sheets, it can be sufficiently softened even when water having high hardness such as industrial water is used. 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 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 a combination with the polyoxyethylene alkyl ether of the general formula (1).

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail. As the alkali agent used in the present invention,
Any water-soluble alkali agent can be used. Specific examples include hydroxides of alkali metals such as sodium hydroxide and potassium hydroxide, and silicates such as sodium orthosilicate, sodium metasilicate, sodium sesquisilicate, sodium silicate No. 1, sodium silicate No. 2, sodium silicate No. 3, and the like. Salts, phosphates such as sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, disodium carbonate, sodium hydrogen carbonate, dipotassium carbonate,
Carbonates such as potassium bicarbonate; borates such as sodium borate; 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 polyoxyethylene alkyl ether used in the present invention is represented by the following general formula (1): R--O-(CH ₂ CH ₂ O) nH (1) R is a linear or branched alkyl or alkenyl group having 5 to 12 carbon atoms;
In the case of 10 linear or branched alkyl or alkenyl groups, the average number of added moles n of the oxyethylene group is 1
When R is a linear or branched alkyl or alkenyl group having 11 to 12 carbon atoms, the average number of added moles n of the oxyethylene group is 6 to 20. Preferably, R is a linear or branched alkyl or alkenyl group having 6 to 10 carbon atoms, and when R is a linear or branched alkyl or alkenyl group having 6 to 8 carbon atoms, oxyethylene The average number of added moles n of the group is 1 to 10, and when R is a linear or branched alkyl or alkenyl group having 9 to 10 carbon atoms, the average number of added moles n of the oxyethylene group is 4 to 10. is there. Even more preferably, when R is a linear or branched alkyl or alkenyl group having 6 to 7 carbon atoms, the average addition mole number n of the oxyethylene group is 2 to 8, and R has 8 to 8 carbon atoms.
In the case of 10 linear or branched alkyl or alkenyl groups, the average number of added moles n of the oxyethylene group is 4 to 8. As a specific example, Kao Corporation's Emulgen 109P
(R: dodecyl group, n: 9), manufactured by Aoki Yushi Kogyo Co., Ltd.
BLAUNONEL-1303 (R: decyl group, n: 3), BLAUNON EL
-1305 (R: decyl group, n: 5), BLAUNON EL-1506
(R: dodecyl group, n: 6), BLAUNON EL-1507 (R:
Dodecyl group, n: 7.5), BLAUNON EL-1509 (R: dodecyl group, n: 9), BLAUNON EL-1510 (R: dodecyl group,
n: 10), BLAUNON EL-1513 (R: dodecyl group, n: 1)
3), BLAUNON EL-1515 (R: dodecyl group, n: 15), BL
AUNON EH-2 (R: 2-ethylhexyl group, n: 2), BLAU
NON EH-4 (R: 2-ethylhexyl group, n: 4), BLAUNO
NEH-6 (R: 2-ethylhexyl group, n: 6), BLAUNON
EH-11 (R: 2-ethylhexyl group, n: 11), Nippon Emulsifier Co., Ltd. hexyl glycol (R: hexyl group,
n: 1), hexyl diglycol (R: hexyl group,
n: 2), 2-ethylhexyl glycol (R: 2-ethylhexyl group, n: 1), 2-ethylhexyl diglycol (R: 2-ethylhexyl group, n: 2), sophanol L70 (R: secondary) manufactured by Nippon Shokubai Co., Ltd. Decyl, undecyl,
Dodecyl group, n: 7), sophthanol L90 (R: secondary decyl, undecyl, dodecyl group, n: 9), sophthanol L120 (R: secondary decyl, undecyl, dodecyl group,
n: 12). Two or more polyoxyethylene alkyl ethers may be combined.

The water-soluble high-molecular carboxylic acid used in the present invention has the general formula (2)

[0018]

Embedded image

This is shown in FIG. 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 ends of the general formula (2) are not particularly limited, a hydrogen atom, OH, and a carbon atom of 1
To 5 alkyl groups, an alkoxyl group having 1 to 5 carbon atoms, SO ₃ M, etc., 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. m and n each indicate the number of moles of the monomer in parentheses, and m may be 0. If m is 0,
It becomes a homopolymer of a monomer whose mole number is represented by n. The copolymerization molar ratio m / n of m and n is 0/10 to 10/1, and the weight average molecular weight (MW) is 1,000 to 100,000, preferably 3,000.
0 to 50,000, more preferably 5,000 to 20,000. The polymerization form may be block or random. Specific examples include acrylic acid homopolymer, acrylic acid-maleic acid copolymer, α-hydroxyacrylic acid homopolymer, C
5-olefin-maleic acid copolymer, isobutylene-maleic acid copolymer, and the like, and alkali metal salts or amine salts thereof. Preferred are acrylic acid homopolymer and acrylic acid-maleic acid copolymer.
Specific product names include Kao Corporation's Poise 540,
Poise 530, Poise 521, Poise 520, Pale Plaque 250, Pale Plaque 120 manufactured by Nippon Peroxide Co., Ltd.
0, Pale Plaque 5000, Quinflow 540, Quinflow 542, Quinflow 543, Quinflow 560, Quinflow 640, Quinflow 750, Alon T-40 (M) manufactured by Toagosei Co., Ltd. Kuraray's Isoban 06, Isoban 04, Isoban 600, and Nippon Shokubai's 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 amount of the composition of the present invention at the time of cleaning a steel sheet will be described. The amount of the alkali agent in the composition is preferably 0.5 to 10.0% by weight, more preferably 1.0 to 8.0% by weight at the time of cleaning a steel sheet. It is. If it is less than 0.5% by weight at the time of cleaning a steel sheet, the cleaning performance is poor. If it exceeds 10.0% by weight, the cleaning performance tends to be saturated, but it is economically disadvantageous.
Particularly preferably, sodium hydroxide is added at the time of washing the steel sheet.
Used at a blending amount of ~ 8.0 wt%. In addition, in selecting and blending the alkaline agent, it is desirable that the pH at the time of cleaning the steel sheet is in a range exceeding 12.5 from the viewpoints of detergency and electric conductivity.

The amount of the polyoxyethylene alkyl ether to be added to the composition of the present invention is preferably 0.05 to 5.0% by weight, more preferably 0.1 to 3.0% by weight when the steel sheet is washed. Less than 0.05% during cleaning of steel sheet is inferior in cleaning performance, 5.0 wt%
%, The cleaning performance tends to be saturated, but the COD increases, which is economically disadvantageous. In the above general formula (1), R is a straight-chain or branched-chain alkyl or alkenyl group having 6 to 7 carbon atoms, and the average addition mole number n of the oxyethylene group is 2 to 8; A linear or branched alkyl or alkenyl group having a number of 8 to 10 and an average number of added moles n of the oxyethylene group of 4 to 8 has a compounding amount of 0.1 to 2.0 wt% at the time of washing the steel sheet. Good detergency is obtained. In particular, dioxyethylene hexyl ether, tetraoxyethylene hexyl ether, tetraoxyethylene heptyl ether, tetraoxyethylene octyl ether, hexaoxyethylene octyl ether, tetraoxyethylene nonyl ether, tetraoxyethylene 2-ethylhexyl ether,
Hexaoxyethylene 2-ethylhexyl ether can provide good cleaning properties even at 0.1 to 1.0 wt% when cleaning steel sheets. The amount of the water-soluble high-molecular carboxylic acid to be added to the composition of the present invention is preferably 0.05 to 1.0% by weight, more preferably 0.1 to 0.5% by weight, when the steel sheet is washed. 0.05wt when cleaning steel plate
%, Water with high hardness such as industrial water cannot be sufficiently softened, and calcium ions and magnesium ions form water-insoluble salts with fatty acids mixed in as dirt, resulting in poor cleaning. More likely to be the cause. Further, even if it is added in excess of 1.0 wt%, the water softening ability is saturated, but the COD is increased, which is economically disadvantageous.

The amount of the aldonic acid to be added to the composition of the present invention is preferably 0.03 to 3.0% by weight, more preferably 0.05 to 2.0% by weight when the steel sheet is washed. 0.03w when cleaning steel plate
If the amount is less than t%, the washing performance is poor, and even if the addition exceeds 3.0 wt%, the washing performance is saturated, but the COD increases, which is economically disadvantageous. In the case of sodium gluconate and sodium glucoheptonate, good detergency can be obtained even at 0.05 to 1.0 wt%.

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 (hereinafter referred to as "high-concentration alkaline cleaning composition") during storage according to the present invention will be described. First, the blending amount of the alkali agent during storage is preferably 20.0 to 48.0 wt%, more preferably 30.0 to 45.0 wt%. 20.0wt% when stored
In the following, the precipitation amount of the water-soluble polymer carboxylic acids is small,
Poor stability due to inability to maintain stability as slurry, 4
If it is added in excess of 8.0 wt%, 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 wt% during storage.

The amount of the polyoxyethylene alkyl ether to be added to the high-concentration alkaline detergent composition of the present invention is as follows:
During storage, it is preferably 0.1 to 30.0 wt%, more preferably 0.2 to 20.0 wt%, and even more preferably 0.5 to 20.0 wt%. If it is less than 0.1% by weight during storage, the necessary concentration of polyoxyethylene alkyl ether at the time of cleaning the steel sheet cannot be obtained. Also, since this composition is stabilized in a slurry state,
If the polyoxyethylene alkyl ether having a low specific gravity is too large, it will be easy to separate, and if added in excess of 30.0 wt% during storage, the product stability will be 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, more preferably 1.0 to 8.0 w% during storage.
t%. If it is less than 0.5 wt% during storage, the product stability is poor, and if it exceeds 10.0 wt%, 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
0), acrylic acid-maleic acid copolymer (MW: 5,000 to
20,000) and / or 1.0 to 6.0 wt.
%.

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 preferably from 0.05 to 20.0 wt%, more preferably from 0.1 to 15.0 wt%, and even more preferably from 0.5 to 15.0 wt%. If it is less than 0.05% by weight during storage, the concentration of aldonic acids required for cleaning the steel sheet cannot be obtained. If more than 20.0 wt% is added during storage, the amount of water required to dissolve the aldonic acid increases, and the required amount of alkali agent and water-soluble polymer carboxylic acid required for product stabilization can be added. Disappears.

The alkaline cleaning 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.

Further, 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 adheres, and that the synthetic ester of 70% is used.
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, and 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.

Further, the alkaline detergent composition for steel sheets of the present invention is effective for steel sheets to which a 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 cleaning steel sheets of the present invention contains at least 50% by weight of a synthetic ester and has an acid value of 10%.
This is particularly effective for a steel sheet to which a rolling oil having a KOH mg / 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 a high-viscosity ester of 10% by weight or more adheres, and a high-viscosity ester of 20% by weight or more. 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 washing property, such as nitrilotriacetic acid, ethylenediaminetetraacetic acid, ethylenediaminediacetic acid, and 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 further comprises a surfactant generally used for improving detergency, for example, a nonionic surfactant, an anionic surfactant, 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.

[0040]

EXAMPLES Preparation of Steel Sheet 1 to be Cleaned Steel sheet 1 to be cleaned was prepared by the following procedure. That is, a steel sheet cold-rolled with tallow-based rolling oil is cut into a size of 25 mm × 50 mm, and the rolling oil adhering to the surface is removed with n-hexane. Then, it is preliminarily heat-degraded by an ISOT
A commercially available tallow-based rolling oil increased to 0 to 150 mm ² / S was prepared by adhering to a coating amount of 200 mg / m ² .

Preparation of the Steel Plate 2 to be Cleaned The steel plate 2 to be cleaned was prepared by the following procedure. That is, the components shown in Table 16 below were blended in the amounts shown in Table 17, and a steel sheet was cold-rolled using the prepared rolling oil, and cut into a size of 25 mm × 50 mm.

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.

Method for measuring residual oil content The oil content on the steel sheet surface after the cleaning test was all measured using a steel oil adhesion 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 of the detergent composition at high concentration during storage at room temperature was evaluated by observing the change over time in the state of the composition. The symbol X indicates that the sample was separated or not homogenized in one day, and the symbol ○ indicates that the sample was not separated and uniform in one day.

The results of the cleaning test and the product stabilization test under the above conditions are shown in Tables 1 to 18. The water-soluble high molecular carboxylic acids in Table 8 and thereafter are shown using the abbreviations used in Tables 6 and 7. Tables 1 to 5 and 8 to 14 show the results of using the steel plate 1 to be cleaned in the cleaning test, and Table 18 shows the results of using the steel plate 2 to be cleaned in the cleaning test.

[0047]

[Table 1]

[0048]

[Table 2]

[0049]

[Table 3]

[0050]

[Table 4]

[0051]

[Table 5]

[0052]

[Table 6]

[0053]

[Table 7]

[0054]

[Table 8]

[0055]

[Table 9]

[0056]

[Table 10]

[0057]

[Table 11]

[0058]

[Table 12]

[0059]

[Table 13]

[0060]

[Table 14]

[0061]

[Table 15]

[0062]

[Table 16]

[0063]

[Table 17]

[0064]

[Table 18]

First, Tables 1 to 3 show the results of comparison of the detergency of various polyoxyethylene alkyl ethers using sodium hydroxide at a concentration of 2.0% by weight as the alkaline agent. As is clear from Tables 2 and 3, the evaluation of the detergency of the composition of the present invention is all good or better even at a low temperature, but if it is out of the specified range (Table 1), it may be good or excellent at a high temperature. However, it can be seen that all are poor under low temperature conditions.

Table 4 shows that sodium hydroxide was used as the alkali agent.
The results of comparing the effect of the concentration of polyoxyethylene alkyl ether on the detergency using a concentration of 2.0% by weight are shown. As is clear from Table 4, the composition of the present invention has good detergency. When the addition amount is 15 wt% or 20 wt%, the cleaning property is increased, but the tendency of saturation is observed.

Table 5 shows the results of comparison of detergency with respect to types and concentrations of alkali agents and / or aldonic acids. As is clear from Table 5, the composition of the present invention has good detergency, and the addition of aldonic acids further improves the detergency.

Tables 6 and 7 show that sodium hydroxide (40.0 wt%) as an alkaline agent and dioxyethylene hexyl ether (4.
0 wt%) and the results of evaluating the product stability of a high-concentration alkaline detergent composition in which various water-soluble high-molecular carboxylic acids were added in the amounts shown in the table. Both ends of the water-soluble high molecular carboxylic acids are all OH groups, and the balance is deionized water. As can be seen from these tables, the compositions of the present invention are stable.
In particular, good results have been obtained when the added amount is in the range of 0.5 to 10.0 wt%. In Tables 6 and 7, when the concentration of the water-soluble high molecular carboxylic acid is 12.0 wt%, the stability is good, but the viscosity is high, so that the fluidity is low, and therefore the transportability is poor. The molecular weight in the table indicates the weight average molecular weight,
It was measured by gel permeation chromatography (GPC) using polyethylene glycol as a standard.

Tables 8 to 10 show that sodium hydroxide was used as an alkali agent at a concentration of 34.0 wt%, and that water-soluble polymer carboxylic acid (WPC-3) was used as a water-soluble polymer carboxylic acid.
The results of comparing the cleaning properties of a high-concentration alkaline cleaning composition containing various polyoxyethylene alkyl ethers at a concentration of t% are shown. The cleaning test was performed by diluting the composition shown in the table 17 times with water. As is clear from Tables 9 and 10, the compositions of the present invention were all evaluated as good in cleaning performance, but out of the specified range (Table 8), the results were poor. Further, all the compositions of the present invention exhibited good (○) stability.

Tables 11 and 12 show that a high-concentration alkaline detergent was prepared using sodium hydroxide as an alkali agent and a water-soluble high-molecular carboxylic acid (WPC-4) at a concentration of 2.5 wt% as a water-soluble high-molecular carboxylic acid. The result of having compared the influence of the density | concentration of polyoxyethylene alkyl ether on detergency when making it into a composition is shown. The cleaning test was performed by diluting the composition shown in the table with water 10 times in Table 11 and twice in Table 12 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 13 and 14 show the results of comparison of the detergency and product stability of the high-concentration alkaline detergent composition by changing the type and concentration of the alkaline agent and / or aldonic acid. The cleaning test was performed by diluting the composition shown in the table 20 times with water. As is clear from these tables, the composition of the present invention has good detergency and is stable. Table
Comparing Table 13 with Table 14, it can be seen that the detergency is further improved by including aldonic acids.

Table 15 shows that sodium hydroxide (40.0 wt%) was used as an alkali agent, and dioxyethylene hexyl ether (4.0 wt%) was used as a polyoxyethylene alkyl ether.
FIG. 3 shows the results of comparing the product stability of high-concentration alkaline detergent compositions using the above-mentioned compounds by changing the type and concentration of various water-soluble polymer carboxylic acids. Table 15 shows that the composition of the present invention is stable. In particular, good results have been obtained when the added amount is in the range of 0.5 to 10.0 wt%.
As in the case of Tables 6 and 7, the stability is good even when the concentration of the water-soluble high-molecular carboxylic acids is 12.0 wt%.
Due to the high viscosity, the fluidity is low, and therefore the transportability is poor.

Table 18 shows that sodium hydroxide was used as the alkaline agent.
The results of comparison of the cleaning properties against different rolling oils using the cleaning agents shown in Table 18 as examples and comparative examples, respectively, using a concentration of 2.0% by weight 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.

[0074]

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, 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, so that detergent concentration control is easy and stable operation is possible. Will be possible.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C11D 3/37 C11D 3/37 10/02 10/02 C25F 1/00 C25F 1/00 B

Claims (8)

[Claims] An alkali agent and a general formula (1) R—O— (CH ₂ CH ₂ O) nH (1) (wherein, R is a linear or branched alkyl group having 5 to 12 carbon atoms or An alkenyl group, n represents an average number of moles of the added oxyethylene group, and when R has 5 to 10 carbon atoms, n is 1
-20, when R has 11-12 carbons, n is 6-20)
And at least one of the polyoxyethylene alkyl ethers shown in (1). 2. An alkali agent and a compound represented by the following general formula (1): R—O— (CH ₂ CH ₂ O) nH (1) (wherein R represents a linear or branched alkyl group having 5 to 12 carbon atoms or An alkenyl group, n represents an average number of moles of the added oxyethylene group, and when R has 5 to 10 carbon atoms, n is 1
-20, when R has 11-12 carbons, n is 6-20)
And at least one polyoxyethylene alkyl ether represented by the following formula (2): (Wherein, R _{1 to} R _{6 are} hydrogen, an alkyl group having 1 to 5 carbon atoms,
C1-C5 alkoxyl group, COOM, or OH M: hydrogen, alkali metal, C1-C4 alkylamine, or C1-C6 alkanolamine m / n (copolymerization molar ratio): 0 / An alkali detergent composition for steel sheets, comprising at least one water-soluble high molecular carboxylic acid having a weight average molecular weight (MW) of from 10 to 10/1 (1,000 to 100,000). 3. The alkaline detergent composition for a steel sheet according to claim 1, further comprising at least one aldonic acid. 4. The alkaline cleaning composition for a steel sheet according to claim 1, which is used for electrolytic cleaning of a cold-rolled steel sheet. 5. The method according to claim 1, which is used for washing a steel sheet containing at least one kind of synthetic ester in an amount of 50% by weight or more and / or a rolling oil having an acid value of 10 KOH mg / g or more. 4. The alkaline detergent composition for a steel sheet according to any one of 4. 6. The method according to claim 1, which is used for washing a steel sheet to which a rolling oil containing at least one kind of high-viscosity ester (70 mm ² / s (40 ° C. or more)) of 10% by weight or more adheres.
The alkaline detergent composition for a steel sheet according to any one of Items 1 to 5, above. 7. A steel sheet to which a rolling oil containing 1% by weight or more of at least one polymer of a higher aliphatic unsaturated acid having 16 to 20 carbon atoms adheres is used for cleaning a steel sheet. The alkaline cleaning composition for a steel sheet according to any one of 1 to 6. 8. The alkaline cleaning composition for a steel sheet according to claim 1, which is used when cleaning is performed at a high line speed of 500 m / min or more.