JPH11158492A - Detergent composition for steel sheet surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a detergent compsn. which is excellent in biodegradability and enables an oily component and iron compds. to be removed in a short time from the surface of a steel sheet by incorporating an amino acid type chelate agent and a gluconic acid salt into the same. SOLUTION: This compsn. is prepd. by compounding 1 pt.wt. anionic and/or nonionic surfactant, 0.01-10 pts.wt., pref. 0.05-5 pts.wt., amino acid type chelate agent comprising either an amino acid-N,N-diacetic acid (or its salt) of formula I (wherein X is H, methyl, or -Cn H2n -Y; Y is COON or OH; M is H, an alkali metal, ammonium, or an amine; m is 0-3; and n is 0-2) or ethylenediaminedisuccinic acid (or its salt) of formula II (wherein Z is H or OH), 0.01-10 pts.wt., pref. 0.05-5 pts.wt., gluconic acid salt, and an alkali builder in an amt. of 0.01-10 pts.wt., pref. 0.03-3 pts.wt., based on 1 pt.wt. amino acid type chelate agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a low-carbon steel sheet, a carbon-containing steel sheet, a low-alloy steel sheet, a stainless steel sheet and the like (hereinafter referred to collectively as a steel sheet) manufactured through a cold rolling step using a rolling oil. The present invention relates to an alkaline surface cleaner having an excellent effect of removing fats and oils and iron adhering to the surface, and having a high wastewater treatment property (biological treatment property).

[0002]

2. Description of the Related Art A steel sheet manufactured through a cold rolling step using a rolling oil is usually annealed after degreasing and washing. Therefore,
In the degreasing and washing step, if the removal of oils and fats or iron oxides such as iron oxides and fine iron powder on the steel sheet surface is insufficient, surface defects such as carbon stains and yellowing of the steel sheet surface are likely to occur in the annealing step. Furthermore, when a steel sheet is plated due to these surface defects, the tendency to generate plating defects or poor plating appearance increases. Also,
When used after painting, this may cause uniform undercoating treatment defects. For this reason, conventionally, for the purpose of cleaning the steel sheet after cold rolling, various degreasing cleaning agents used in the degreasing cleaning process after rolling, or in order to omit this degreasing cleaning process, Various surface cleaners for use in the final stand have been studied.

[0003] These are composed of an alkali builder as a main component and a surfactant, a chelating agent or a defoaming agent added thereto (JP-B-53-6093 and JP-B-62-53600). Or a neutral to weakly alkaline aqueous solution comprising a surfactant and an organic chelating agent based on oxycarboxylic acid, aminocarboxylic acid, phosphonocarboxylic acid, or aminophosphonic acid (JP-B-53-100131). No., Japanese Patent Publication No. 54-10236
No., Japanese Patent Publication No. 54-10237, etc.).

[0004] However, these conventional techniques are effective in removing oils and fats on the surface of a steel sheet, but they are not always sufficient in removing iron oxides, iron powders and the like adhering to the surface of the steel sheet. It is not obtained or the processing time is long (generally several hundreds) in order to obtain the desired sufficient cleaning effect.
Secondly), a sufficient cleaning effect has not been obtained by the processing with a processing time of several tens of seconds corresponding to the recent improvement in productivity. Furthermore, in the prior art, a chelating agent typified by ethylenediaminetetraacetic acid salt (EDTA) is often included in performance, but there is a concern that the lack of biodegradability of EDTA may affect the environment. Yes,
The use of various chelating agents or mixtures of various organic acids instead of EDTA has been studied, but is not satisfactory in terms of cleaning performance. In addition, nitrilotriacetic acid (NT
Although the problem of EDTA is greatly improved by the use of A), NTA is suspected of carcinogenicity and is not preferable in terms of safety.

[0005]

As described above, in the prior art, removal of fats and oils and iron adhering to the surface of a steel sheet is not sufficient, and this tendency is remarkable especially in a short-time surface cleaning treatment. In other words, the seizure of rolling oil on the steel sheet surface, the adhesion of iron oxides, the generation and adhesion of iron soap, etc.
It is not always satisfactory in the prior art to sufficiently clean a steel sheet surface in a short time. Further, there is a demand for a biodegradable cleaning agent that is environmentally friendly.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned conventional problems, and as a result, a composition characterized by containing an amino acid-type chelating agent and a gluconate salt has been obtained. The present invention has been found to be useful as a surface cleaner for steel sheets, and further includes an amino acid-type chelating agent (A component) comprising an amino acid-N, N-diacetate (salt) and / or an ethylenediaminedisuccinic acid (salt) compound, and gluconates (B component), alkali builder (C component) and surfactant (D
Component) as a main component, and the cleaning performance at the time of cleaning at a pH of 10 to 14, especially the cleaning performance at a pH of 10 to 14 is superior to that of the single component due to the synergistic effect of each component. In a short time (generally about 10 seconds), oil and iron can be removed from the surface of the steel sheet, that is, high-speed rolling for the purpose of improving the productivity of the recent cold rolling process. The present invention has been found to be suitable and to have excellent biodegradability, that is, to have good wastewater treatment properties, and completed the present invention.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The amino acid type chelating agent of the component (A) used in the present invention may be any one which has been known as an amino acid type chelating agent, and is particularly represented by the following general formula (1). The amino acid-N, N-diacetate (salt) and the ethylenediaminedisuccinic acid (salt) compound represented by the following general formula (2) are preferred.

[0008]

Embedded image (Wherein, X represents a hydrogen atom, a methyl group or -C _n H _2n -
Represents a group represented by Y, Y represents a COOM group or a hydroxyl group, COOM independently represents a carboxyl group or an alkali metal salt, an ammonium salt or an amine salt thereof;
m represents an integer of 0 to 3, and n represents an integer of 0 to 2. )

[0009]

Embedded image (In the formula, Z represents a hydrogen atom or a hydroxyl group, and COOM independently represents a carboxyl group or an alkali metal salt, an ammonium salt or an amine salt thereof.) The amino acid-N, N-diacetate (salt) and ethylenediaminediamine The succinic acid (salt) compound is synthesized by a known method. Although at least one kind is used as a component of the detergent composition of the steel sheet of the present invention, two or more kinds can be used in combination. When these amino acid type chelating agents are used as salts, alkali salts such as sodium salts and potassium salts, amine salts and ammonium salts are suitable. Among them, a sodium salt is preferred.

The amino acid type chelating agent used in the present invention is preferably, for example, α-alanine-N, N-diacetate (salt), aspartic acid-N, N-diacetate (salt), glutamic acid-N, N-diacetate (salt), serine-N, N-diacetate (salt), and ethylenediamine-N, N-disuccinic acid (salt). Particularly, its sodium salt is preferable. As the amino acid moiety, any of the optical isomers having D-form, L-form and D, L-form can be used, but the L-form is preferable from the viewpoint of biodegradability. The amino acid type chelating agent has a chelating ability, has excellent ability to remove iron on the surface of the steel sheet by a chelating action, has excellent degreasing properties, and easily cleans oil stains adhered to the steel sheet surface. In addition, when used in combination with a surfactant, the degreasing effect is greatly improved, and a synergistic effect of both occurs. As the effect of the surfactant, the cleaning effect is exerted by the comprehensive action of wet penetration, emulsification, and dispersion of the rolling oil contaminants adhering to the steel sheet surface.

The surfactant of the component (D) used in the present invention is an anionic surfactant and / or a nonionic surfactant, and is not particularly limited. In the case of the anionic surfactant, a linear alkylbenzene sulfonate is used. And sulfonates such as higher alcohol sulfates and higher alkyl ether sulfates, and the like. Examples of the nonionic surfactant include polyethylene glycol type nonionic surfactants such as higher alcohol ethylene oxide adducts and alkylphenol ethylene oxide adducts, and polyhydric alcohol type nonionic surfactants. Contains more than one species.

By using the gluconate salt of the component (B) of the detergent composition of the present invention together with the amino acid type chelating agent, the effect of removing iron is synergistically improved. Gluconic acids are compounds represented by the following general formula (3),
In 12 or more regions, the iron ion blocking ability is excellent. M
_{OOC- {CH (OH)} 4} -CH 2 OH
In the formula (3), COOM represents a carboxyl group (M is a hydrogen atom), an alkali metal salt thereof (M is an alkali metal), an ammonium salt or an amine salt, and usually a sodium salt is preferred.

The alkali builder of the component (C) used in the present invention comprises at least one selected from alkali metal hydroxides, alkali metal carbonates and alkali metal silicates. Examples of the alkali metal hydroxide include hydroxides of sodium, potassium and lithium, such as sodium hydroxide and potassium hydroxide. As the alkali metal carbonate, sodium or potassium carbonate or bicarbonate, specifically sodium carbonate,
Potassium carbonate and the like. Examples of the alkali metal silicate are silicates of sodium, potassium and lithium, and specific examples thereof include sodium orthosilicate and sodium metasilicate. Usually, sodium hydroxide or sodium silicate is preferred as the alkali builder. The blending amount of the steel sheet as the surface detergent composition is 0.25 to 90% by weight of the above-mentioned surfactant. The amino acid type chelating agent is used in an amount of 0.1 part by weight based on 1 part by weight of the above surfactant.
The amount is from 0.01 to 10 parts by weight, preferably from 0.05 to 5 parts by weight. When the amount is small, the cleaning effect is not exhibited, and when the amount is too large, the effect does not change. Gluconate is used in an amount of 0.01 to 10 parts by weight, preferably 0.05 to 1 part by weight of the surfactant.
The cleaning effect is not exhibited when the amount is small, and the effect is not changed when the amount is too large. Further, the alkali builder is used in an amount of 0.01 to 10 parts by weight, preferably 0.03 to 3 parts by weight, based on 1 part by weight of the salt of the amino acid type chelating agent.

The detergent composition of the present invention has a pH of 10 to 1.
4, and preferably 12 to 13, the cleaning effect of the steel sheet of each component works synergistically. At this time, a pH buffer such as monoethanolamine may be added for pH adjustment. In particular, in a region exceeding pH 12, the cleaning effect is high, and an advantage is obtained that the rust resistance of the steel sheet after the rinsing treatment is improved, probably because a nonconductive film is formed on the steel sheet surface after cleaning. When the detergent composition of the present invention is to be applied to a steel sheet, and is uniformly and rapidly diluted to a very low concentration of several percent or less as an active ingredient, salts of amino acid type chelating agents, gluconates, alkali builders,
It is preferable to prepare in advance an aqueous solution containing a surfactant as a main component, or to prepare an aqueous solution with an extremely high concentration but easy to handle so that it can be rapidly diluted to the use concentration. May be used in the form of being diluted according to the degree of use. When high concentration is required from the viewpoint of storage and transportation, a solubilizing agent may be added, or other additives such as an antifoaming agent may be used.

The detergent composition of the present invention can be applied to any of the immersion method, the electrolytic treatment method and the spray method, but because of the excellent performance of the detergent according to the constitution of the present invention,
Sufficient cleaning is possible by a treatment in a very short time (generally about 10 seconds), that is, it is possible to remove dirt such as burning oil on a steel sheet surface, adhesion of iron oxide, and formation and adhesion of iron soap. The use of the spray method is preferred from the viewpoint of improving productivity by high-speed rolling in recent years. Regarding the processing temperature, the conventional cleaning conditions often require a cleaning temperature of about 40 to 90 ° C., but according to the present invention, a satisfactory cleaning effect can be obtained even at a low temperature of 40 ° C. or less. It is also economical in terms of energy costs. The amino acid type chelating agent used in the present invention can be easily biodegraded, whereas EDTA conventionally used lacks in biodegradability due to its performance. The detergent composition of the present invention, as well as its performance, as a biodegradable detergent, wastewater after cleaning treatment is also easy to treat with activated sludge, and is an excellent environmentally friendly product. is there.

[0016]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

Examples 1 to 18 According to the compositions shown in Tables 1 and 2 (the remainder being water), detergent compositions of the present invention were prepared and evaluated as follows. The results are shown in Table 3. [Comparative Examples 1 to 15] Compositions shown in Tables 3 and 4 (the remainder is water)
, A detergent composition for comparison was prepared and evaluated in the same manner as in the examples. The results are shown in Table 3.

(Test Material) A steel sheet (low carbon steel sheet) sampled immediately after cold rolling was cut into a piece of 300 × 300 mm to obtain a test material. (Cleaning method and conditions) A temperature of 60 ° C or 3
At 5 ° C., the detergent compositions of Examples and Comparative Examples of the present invention were diluted with water to a concentration of 30 g / L, and the spray pressure was 2 kg / c.
10 seconds spray m ^{2, and} the roll pass speed 300mm
Brushing treatment with a roll was performed for / 10 seconds, and each evaluation was performed after washing with 1 L of running water and drying with a dryer.

(Evaluation of Detergency) The cleaned sample was immersed in a water bath filled with water for 1 minute, pulled up, allowed to stand for 30 seconds, and evaluated by a water leak area.

(Evaluation of residual oil content and iron content) The cleaned sample was subjected to ultrasonic cleaning in carbon tetrachloride for 10 minutes, and the change in weight before and after the cleaning and the amount of iron removed in the carbon tetrachloride were measured. did. The iron content was determined by evaporating the carbon tetrachloride by heating the iron content contained in the carbon tetrachloride, dissolving it in an aqueous hydrochloric acid solution, and determining the iron content by an atomic absorption spectrophotometry. The residual oil content and the residual iron content were expressed and evaluated as residual rates (%) based on the following formulas.

Remaining oil content (%): [(weight of sample after cleaning−weight after ultrasonic cleaning in carbon tetrachloride) / surface area of sample−content of iron content in carbon tetrachloride] / adhesion before cleaning oil amount × 100 clean before deposition of the oil amount 180 mg / m ² residual iron (%): four peeled iron weight / specimen surface area in carbon tetrachloride) / iron of cleaning prior to deposition iron weight × 100 cleaned prior to deposition 190 mg / m ²

(Evaluation of Appearance) The appearance of the cleaned sample was observed, and after attaching a cellophane tape to the sample, the cellophane tape was peeled off, and the result of observation of dirt attached to the tape was comprehensively evaluated. Evaluation criteria: ◎: Surface appearance is uniform, with little adhesion to cellophane tape ○: Uniform surface appearance, but small amount of adhesion to cellophane tape is observed △: Discolored area on surface Is slightly observed and a small amount of deposits on cellophane tape is observed. ×: When discolored portions are considerably observed on the surface, or when large amounts of deposits on cellophane tape are observed.

(Biodegradability test) The detergent compositions of the present invention of Examples 1 and 2 were diluted with water so as to have a COD of 500 ppm. Furthermore, activated sludge is collected from the activated sludge facility that is treating the wastewater of the chemical industry, and this activated sludge is supplied to a small aerated activated sludge facility together with the above-mentioned diluent, and aerated to conduct a biodegradation test. Was. After about one week, the COD in the treated wastewater was reduced to about 25 to 50 ppm, and the decomposition rate was 90 to 95%.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

[0027]

[Table 4]

[0028]

[Table 5]

[0029]

[Table 6]

[0030]

According to the prior art, the removal of fats and oils and iron adhering to the surface of a steel sheet is not sufficient, and this tendency is remarkable especially in a short-time surface cleaning treatment. In other words, it was not always possible to adequately clean the steel sheet surface in a short period of time against the seizure of rolling oil on the steel sheet surface, the adhesion of iron oxides, the generation and adhesion of iron soap, etc. . According to the present invention, it is possible to provide a detergent which can sufficiently cope with these problems and has good biodegradability in consideration of the environment.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C23G 5/036 C23G 5/036 (72) Inventor Toru Yamamoto 2-3-3 Chidoricho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Showa Denko Co., Ltd. Kawasaki Plant (72) Inventor Nobuyoshi Nambu 3-3-3 Hinagahigashi, Yokkaichi-shi, Mie Chubu Killest Co., Ltd. Yokkaichi Plant (72) Inventor Masanori Furukawa 3-3-1 Hinagahigashi, Yokkaichi-shi, Mie Chubu Kirest Co., Ltd. Yokkaichi Plant

Claims (7)

[Claims] 1. A steel sheet surface cleaner composition comprising (A) an amino acid type chelating agent and (B) gluconates. (2) The amino acid type chelating agent is represented by the following general formula (1): (Wherein, X represents a hydrogen atom, a methyl group or -C _n H _2n -
Represents a group represented by Y, Y represents a COOM group or a hydroxyl group, COOM independently represents a carboxyl group or an alkali metal salt, an ammonium salt or an amine salt thereof;
m represents an integer of 0 to 3, and n represents an integer of 0 to 2. )) Or an amino acid represented by the following general formula (2): (1) wherein Z represents a hydrogen atom or a hydroxyl group, and COOM independently represents a carboxyl group or an alkali metal salt, an ammonium salt or an amine salt thereof. The surface detergent composition for a steel sheet according to the above. 3. The steel sheet surface detergent composition according to claim 1, further comprising (C) an alkali builder and (D) a surfactant comprising an anionic surfactant and / or a nonionic surfactant. . 4. The composition according to claim 1, wherein (A) the amino acid type chelating agent is a sodium salt, a potassium salt, an ammonium salt or an amine salt. 5. The composition according to claim 3, wherein (C) the alkali builder is an alkali metal hydroxide and / or an alkali metal carbonate and / or an alkali metal silicate. 6. The method according to claim 1, wherein the pH is from 10 to 14.
The surface detergent composition for a steel sheet according to the above. 7. (D) 0.01 to 10 parts by weight of an amino acid type chelating agent per 1 part by weight of a surfactant comprising an anionic surfactant and / or a nonionic surfactant; B) 0.01 to 10 parts by weight of gluconate and (A) 1 part by weight of the amino acid type chelating agent,
The composition according to any one of claims 3 to 6, wherein the alkali builder (C) comprises 0.01 to 10 parts by weight.