JPH06116768A - Phosphorus-free alkaline degreaser for low temperature cleaning of metals - Google Patents

Abstract

(57) [Abstract] [Purpose] A metal surface can be provided with an excellent cleaning effect on a metal surface even when continuously used at a low temperature of 35 to 45 ° C, and having a good chemical conversion treatment property. Provided is a phosphorus-free alkaline degreasing liquid for low temperature cleaning of metals. [Composition] As a component, (A) 0.05 to 0.3% by weight
(B 2) 0.01 to 0.5, and an inorganic builder composed of silicate (converted to SiO ₂ ) and 0.4 to 3.0% by weight of one or more kinds of NaOH, Na ₂ CO ₃ , and NaHCO _3. weight%
One or more of ethylenediaminetetraacetic acid salt and nitrilotriacetic acid salt of 0.1 to 0.5% by weight of polyacrylic acid salt, cyclopentanetetracarboxylic acid, polycarboxylic acid salt, hydroxycarboxylic acid salt, and urethanization An alkaline aqueous solution containing an organic builder consisting of one or more kinds of polyvinyl alcohol and (C) 0.2 to 0.6% by weight of a surfactant, the pH of which is represented by the following relational expression: y = 6 0.0x + 9.2 (where x is the SiO ₂ conversion concentration of the silicate in the aqueous solution), and a phosphorus-free alkaline degreasing solution for metal low-temperature cleaning adjusted between 13 and 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphorus-free alkali degreasing liquid for low-temperature metal cleaning, particularly at low temperatures (35-35).
At 45 ° C.), it relates to a phosphorus-free alkali degreasing liquid for metal low temperature cleaning (hereinafter referred to as an alkali degreasing liquid) suitable for removing oil and dirt from the metal surface of steel plates, zinc-based plated materials, aluminum materials and the like. . More specifically, the present invention relates to a phosphorus-free alkaline degreasing liquid for cleaning the surface of a metal, which is applied before the chemical conversion treatment in order to sufficiently achieve the purposes of the chemical conversion treatment and coating of the metal surface. , This alkaline degreasing liquid does not contain phosphorus which brings about eutrophication of rivers and lakes, especially about 40 ° C (35 ° C
In spray degreasing or immersion degreasing at a low temperature of up to 45 ° C.), it is possible to obtain an excellent surface cleaning effect and obtain a metal surface having good chemical conversion treatability.

[0002]

2. Description of the Related Art Generally, when coating a metal product, a chemical conversion treatment is performed before the coating, but the treatment process is usually surface cleaning (degreasing) → water washing (multi-stage method) → surface adjustment → chemical conversion treatment → water washing (multi-stage). Method) → deionized water washing → draining drying → painting (anion or cation electrodeposition, electrostatic painting, powder coating,
It is done in the order of spraying or painting etc.). The general constituents of alkaline degreasers are builder components, surfactants and antifoaming agents, and the aqueous solution (alkali degreasing liquid) of these components is treated by spraying or dipping. Apply to metal surface to remove oil and dirt. The liquid temperature at that time is usually 40 to 70 ° C., and the degreasing time is about 1 to 10 minutes. These metal products to be treated may be made of a single material, but are often made of a plurality of materials such as a cold rolled steel plate, a zinc-based plated material and an aluminum material.

Recently, with increasing awareness of global environmental protection, there is an increasing demand for non-phosphorization of degreasing agents in order to prevent eutrophication of rivers and lakes. On the other hand, for the purpose of energy saving, there is a great interest in the alkaline degreasing liquid used especially at low temperature. However, most of the alkaline degreasing liquids applied to the above-mentioned cleaning step contain phosphate, polyphosphate or the like as an inorganic builder. Further, a phosphorus-free alkali degreasing solution containing no phosphate or polyphosphate has been reported, but this phosphorus-free alkali degreasing solution is used at a low temperature (35 to 35%) for cleaning the surface as a pretreatment for metal conversion treatment.
When applied at 45 ° C.), there are problems such as lack of degreasing property and generation of chemical conversion failure in the chemical conversion treatment step performed later.

[0004]

The present invention is applied to surface cleaning as a pretreatment of metal conversion treatment, does not contain a compound containing phosphorus element, and is at a low temperature (35 to 45).
To provide a phosphorus-free alkaline degreasing solution for low-temperature metal cleaning, which exerts an excellent surface cleaning effect even when continuously used at (° C) and is effective for obtaining a metal surface having good chemical conversion treatment property. To do.

[0005]

A phosphorus-free inorganic builder comprising a specific amount of a silicate and a specific amount of a specific alkali compound, a specific amount of a specific acetic acid derivative salt, and a specific carboxylic acid salt and / or urethanated polyvinyl alcohol. A phosphorus-free organic builder consisting of and an alkaline aqueous solution containing a specific amount of a surfactant are constituted, and the pH of the alkaline aqueous solution is
It has succeeded in solving the above-mentioned problem by controlling a value between 13 and a specific value determined by the concentration of silicate (value converted into SiO ₂ concentration).

That is, the phosphorus-free alkaline degreasing liquid for low-temperature metal cleaning according to the present invention comprises the following components: (A) 0.05 to 0.30% by weight (however, converted to SiO ₂ ) silicate, and 0.4 to 3.0% by weight of an inorganic builder consisting of at least one selected from sodium hydroxide, sodium carbonate and sodium hydrogen carbonate, and (B) 0.01 to 0.5% by weight of ethylenediaminetetraacetic acid. Salt and at least one selected from nitrilotriacetic acid salt, and 0.1 to 0.5% by weight of polyacrylate, cyclopentanetetracarboxylate, polycarboxylate, hydroxycarboxylate, and urethane. Alkaline water containing an organic builder consisting of at least one selected from the following: polyvinyl alcohol and (C) 0.2 to 0.6% by weight of a surfactant. A liquid, the pH value of the alkaline aqueous solution, the following equation (I): y ≦ A ≦ 13 (I) [where, A is represents the pH value of the alkaline aqueous solution,
y represents the following relational expression (II): y = 6.0x + 9.2 (II) (where x represents the percentage value of the concentration of the silicate compounded in the aqueous solution converted to the SiO ₂ concentration). ) Is a value calculated from. ] Is satisfied.

The alkaline degreasing solution of the present invention comprises, as the above-mentioned surfactant, 0.18 to 0.5% by weight of polyoxyethylene polyoxypropylene nonylphenyl ether.
0.02-0.1% by weight of alkyldimethylamine oxide represented by the following formula:

[Chemical 2] (However, in the above formula, R represents an alkyl group having 12 to 22 carbon atoms).

[0008]

The silicate used in the present invention is added as an inorganic builder for improving degreasing property, and commercially available sodium orthosilicate, sodium metasilicate, etc. can be used. Sodium silicate is supplied in the form of anhydrous salts and various hydrated salts.
₂ It is specified by the converted amount, and the proper concentration range of silicate is
In terms of SiO _2, 0.0 relative to the total weight alkaline degreasing solution
It is 5 to 0.30% by weight. This concentration is 0.05% by weight
When the amount is less than 1, the degreasing property of the obtained alkaline degreasing liquid becomes insufficient, and when it exceeds 0.30% by weight, the degreasing property can be sufficiently secured in the obtained alkaline degreasing liquid,
It is not economical because the effect of increasing the concentration saturates, and when the concentration exceeds 0.30% by weight, the lower limit of the pH of the degreasing liquid to be controlled becomes so high that it is between the upper limit of pH. The control range is narrowed, and in addition, in order to maintain the pH, a large amount of alkali replenishment is required, which is not economical in this sense either. As the silicate used in the present invention, it is also possible to use an alkali metal silicate (for example, potassium salt) other than the sodium salt.

In the present invention, at least one selected from sodium hydroxide, sodium carbonate and sodium hydrogen carbonate is used as another inorganic builder component to be added to the silicate, which is mainly used for pH adjustment. The purpose is to supply an alkaline component. The amount of the alkaline compound blended is appropriately 0.4 to 3.0% by weight based on the total weight of the alkaline degreasing liquid. If the blending amount is less than 0.4% by weight, a sufficient amount of alkali is not supplied, and there is a drawback that the pH lowers rapidly when degreasing is continuously performed in an alkaline degreasing liquid, and it is 3.0. If the content exceeds 10% by weight, there is no particular problem, but since it already contains a sufficient amount of alkali, the pH tends to exceed 13, and etching of zinc-based plating materials and aluminum materials tends to occur excessively. It may adversely affect the chemical conversion processability of the subsequent process.

The organic builder used in the present invention further promotes the effect of improving the degreasing property of the inorganic builder, and comprises 0.01 to 0.5% by weight of ethylenediaminetetraacetic acid salt and nitrilotriacetic acid salt. At least one selected from the group consisting of 0.1 to 0.5% by weight of at least one selected from polyacrylate, cyclopentanetetracarboxylate, polycarboxylate, hydroxycarboxylate and urethanized polyvinyl alcohol. It consists of one kind. In the present invention, the organic builder contributes to the improvement of degreasing property by combining the components selected from the two groups as described above. Regarding the upper limit value and the lower limit value in the concentration range of each component of the organic builder, if the compounding amount is less than the lower limit value, sufficient degreasing property cannot be obtained, and if it exceeds the upper limit value, the effect Is not only saturated, but also has a high COD value, which is disadvantageous in terms of wastewater treatment. Each of the above carboxylic acids is N
a, K and other metal salts or ammonium salts which are water-soluble, polyacrylic acid includes a copolymer with vinyl alcohol and other monomers, and polycarboxylic acid is
For example, it is selected from succinic acid, adipic acid, tricarballylic acid, etc., and hydroxycarboxylic acid is tartaric acid, citric acid,
It is selected from gluconic acid, heptgluconic acid and the like. The urethanized polyvinyl alcohol is selected, for example, from polyvinyl alcohol to which MDI (diphenylmethane diisocyanate) or TDI (tolylene diisocyanate) is added.

The kind of the surfactant used in the present invention is not particularly limited, but its content is 0.
It is 2 to 0.6% by weight. If the blending amount is less than 0.2%, sufficient degreasing property cannot be obtained, or even if sufficient degreasing property is obtained in the initial stage, degreasing will occur continuously and oil content will accumulate in the degreasing liquid. Sex is getting worse. On the other hand, if the content is more than 0.6% by weight, the degreasing property is sufficiently secured, but the effect is saturated, which is economically disadvantageous, and the COD value is high, and wastewater treatment is disadvantageous. There is a problem with points. The surfactant used in the present invention can be selected from those generally used in alkaline degreasing solutions. Known examples of such surfactants include polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene alkylphenyl ether, polyoxyethylene polyoxypropylene alkyl ether, and polyoxyethylene fatty acid ester. Has been.

In the present invention, as the surfactant, 0.
18-0.5% by weight of polyoxyethylene polyoxypropylene nonylphenyl ether, 0.02-0.1
% By weight of alkyldimethylamine oxide represented by the following general formula:

[Chemical 3] [In the formula, R is an alkyl group having 12 to 22 carbon atoms. ] And more stable degreasing property can be secured.

The alkaline degreasing liquid usually contains an antifoaming agent in order to suppress the adverse effects caused by foaming during the washing operation, but the alkaline degreasing liquid of the present invention may also contain an antifoaming agent. This defoaming agent can be appropriately selected and used from those usually used.

When the degreasing solution is continuously degreased with an alkaline degreasing solution, the pH of the degreasing solution gradually decreases with the washing time. The main reason for this is that the alkaline degreasing liquid absorbs carbon dioxide in the air. When the pH is lowered, the degreasing property of the alkaline degreasing liquid is lowered, and when a silicate is used, the lowering of the pH may cause poor chemical conversion in the subsequent phosphate treatment step.

The inventors of the present invention have conducted extensive studies regarding the suitable pH range of the degreasing solution, and as a result, the pH value of the degreasing solution is a value determined by the following formula (II) according to the content of silicate. (Y)
It has been found that the lowering of the chemical conversion treatability can be suppressed by keeping the ratio within the range where the lower limit is 13 and the lower limit is 13. y = 6.0x + 9.2 (II) x: value (%) obtained by converting the concentration of silicate compounded in the degreasing solution into the concentration of SiO ₂ (of course, 0.05 ≦ x ≦ 0.30) y: x PH value determined by

When the pH of the degreasing liquid is less than the value (y) obtained by the above calculation formula, poor chemical conversion, which is considered to be caused by an increase in adsorption of silica on the metal surface and a decrease in etching amount, tends to occur. . Further, if the pH exceeds 13, the metal surface is too strongly etched, which is likely to cause poor chemical conversion. Poor chemical conversion deteriorates not only poor coating and corrosion resistance but also secondary resistance to water resistance after coating. It causes problems.

[0017]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples.

Examples 1 to 13 and Comparative Examples 1 to 9 (Preparation of Degreasing Liquid) (1) Alkaline degreasing liquid (a) Tables 1 to 3 show the results of Examples 1 to 9 and Comparative Examples 1 to 4, respectively. An alkaline degreasing liquid having the above composition was prepared. In the inorganic builder, sodium metasilicate pentahydrate was used as the silicate, and sodium hydroxide and sodium carbonate were used as the alkaline compounds. As the organic builder, disodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium polyacrylate and sodium heptonate were used. Coconut dimethylamine oxide and polyoxyethylene polyoxypropylene nonylphenyl ether were used as the surfactant.

It is assumed that oil is mixed in the degreasing liquid from the object to be treated, and oil (Daphne Oil Coat Z-
3, 0.03% of Idemitsu Kosan Co., Ltd. was added. The procedure for adding the rust preventive oil to the degreasing solution is to add the oil to each alkaline degreasing solution and then add the mixture to a homomixer (TK.
Using Homomixer HU-M, manufactured by Special Machinery Co., Ltd., 1
A method of high-speed stirring at 0000 rpm for 20 minutes was adopted. Table 1 and Table 2 show the pH value and y value of each alkaline degreasing solution.

[0020]

[Table 1]

[0021]

[Table 2]

(B) In each of Examples 10 to 13 and Comparative Examples 5 to 9, carbon dioxide was blown into the degreasing liquid shown in Table 3 or sodium hydroxide was added to adjust the pH value. Adjustments were made as shown in Table 3. The alkaline degreasing liquid whose pH was adjusted in this way was used to test the relationship between the pH of the degreasing liquid and the chemical conversion treatability of the material to be treated, as described later.

[0023]

[Table 3]

(2) Test The following tests were carried out using the alkaline degreasing solutions of Examples 1-13 and Comparative Examples 1-9. (B) Application of test plate and rust preventive oil First, a degreasing test was conducted on a steel sheet, and an alloyed galvanized steel sheet and an aluminum material, which are apt to cause poor chemical conversion, were used for the chemical conversion treatment test. Test plate: Steel plate: SPCC Zinc-based plating material: Alloyed zinc-plated steel plate (silver alloy, manufactured by Nippon Steel Co., Ltd.) Aluminum material: A5032 Anticorrosion oil: Daphne oil coat Z-3 (Idemitsu Kosan Co., Ltd.)
Application of anti-rust oil: Steel plate and galvannealed steel plate
After washing with 1,1-trichloroethane, the above-mentioned rust preventive oil was applied onto the surface by roll coating so that the applied amount was 1 to ² g / m ² . Test plate A: 7 after applying SPCC with rust preventive oil as described above
The one left at room temperature for a day. Test plate B: 6 after applying SPCC to SPCC as described above
What was left for 100 hours in a constant temperature and high humidity container at 0 ± 1 ° C and relative humidity (RH) 95 ± 2%. Test plate C: Silver alloy coated with rust-preventive oil as described above and left at room temperature for 7 days. Test plate D: A5032 uncoated oil.

(B) Degreasing test Each alkaline degreasing solution was heated and kept at 40 ± 1 ° C.,
Make sure that the three test plates are not in contact with each other.
It was dipped for a minute and then washed with spray water for 30 seconds to wash away excess alkali degreasing liquid adhering to the surface of the test plate. Next, the test piece was made vertical and left in the room for 60 seconds, and immediately 3
The water-wetted area (%) of each test plate was measured, and the degreasing property was evaluated by this measured value. Example: 100 ... Completely wet with water (degreasing: excellent) 50 ... 50% with water (degreasing: poor)

(C) Chemical conversion treatment, coating test The above treatment was carried out in the following steps. Degreasing → Washing → Surface preparation → Chemical conversion treatment → Washing → Deionized water washing → Drying → Cationic electrodeposition coating Here, in the degreasing process, each alkaline degreasing liquid is heated and kept at 40 ± 1 ° C., and a test plate is placed therein. It was immersed for 2 minutes. In the washing step, water was sprayed on the surface of the test plate for 30 seconds. In the surface conditioning process, PREPAREN-ZT
(PL-ZT, manufactured by Nippon Parkerizing Co., Ltd.) 2 g /
An aqueous solution containing 1 was sprayed on the surface of the test plate for 20 seconds. In the chemical conversion treatment step, the test plate material was immersed in a treatment liquid containing Palbond-L3080 (PB-L3080, manufactured by Nippon Parkerizing Co., Ltd.) adjusted under standard conditions at a temperature of 43 ° C. for 2 minutes. In the next water washing step, a water solution was performed for 30 seconds, and the deionized water washing step was performed by a spray method for 20 seconds. The drying process was performed in an atmosphere of 105 ° C. for 5 minutes. The coating process is cationic electrodeposition paint HB2000
After painting with L (Kansai Paint Co., Ltd.), 1
It was dried at 75 ° C. for 20 minutes and adjusted so that the dry film thickness was 20 μm.

(D) Water-resistant secondary adhesion test After the electrodeposition coated plate was immersed in deionized water at 40 ° C. for 240 hours,
The following items were evaluated. Cross-cut test: 100 pieces of 1 mm square were scratched with a sharp cutter to reach the base material, and the cellophane tape was peeled off, and then the remaining squares were counted. The larger the number, the better. Bending test: A sharp cutter was used to scratch the base material, the product was bent 90 ° along the damaged line, and the cellophane tape was peeled off. The peeling width was measured and expressed in mm. The smaller the peeling width, the better.

The test results are shown in Tables 4 and 5.

[Table 4]

[0029]

[Table 5]

As clearly shown in Table 4, Examples 1 to 1
The alkaline degreasing solution of No. 9 shows a good degreasing property with a water-wetted area of 100% in both the test plate A and the test plate B, while the plates to be treated with the degreasing solutions of Comparative Examples 1 to 4 are water. The wetted area was less than 100%, and it was confirmed that the degreasing liquid of the present invention had good degreasing properties. Table 5 shows the evaluation results of the water resistant secondary adhesion of the coated plate. Comparing the results of test plate C between the example and the comparative example, a cross-cut test,
Also, in both the 90 ° bending test, Examples 1 to 4 and Examples 10 to 13 had better adhesiveness than Comparative Examples 5 to 9. Similarly, as to the result of the test D, the example showed better adhesion than the comparative example. From the above results, the excellent effect of the alkaline degreasing liquid of the present invention was confirmed.

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[Procedure amendment]

[Submission date] December 22, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

The organic builder used in the present invention further promotes the effect of improving the degreasing property of the inorganic builder, and comprises 0.01 to 0.5% by weight of ethylenediaminetetraacetic acid salt and nitrilotriacetic acid salt. At least one selected from the group consisting of 0.1 to 0.5% by weight of at least one selected from polyacrylate, cyclopentanetetracarboxylate, polycarboxylate, hydroxycarboxylate and urethanized polyvinyl alcohol. It consists of one kind. In the present invention, the organic builder contributes to the improvement of degreasing property by combining the components selected from the two groups as described above. Regarding the upper limit value and the lower limit value in the concentration range of each component of the organic builder, if the compounding amount is less than the lower limit value, sufficient degreasing property cannot be obtained, and if it exceeds the upper limit value, the effect Is not only saturated, but also has a high COD value, which is disadvantageous in terms of wastewater treatment. Each carboxylic acid salt,
Metal salts such as Na and K, or ammonium salts, which are water-soluble, polyacrylic acid includes copolymers with vinyl alcohol and other monomers, and polycarboxylic acids include, for example, succinic acid, adipic acid, It is selected from tricarballylic acid and the like, and the hydroxycarboxylic acid is selected from tartaric acid, citric acid, gluconic acid, heptgluconic acid ( heptonic acid) and the like. The urethanized polyvinyl alcohol is selected, for example, from polyvinyl alcohol to which MDI (diphenylmethane diisocyanate) or TDI (tolylene diisocyanate) is added.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

The inventors of the present invention have conducted extensive studies regarding the suitable pH range of the degreasing solution, and as a result, the pH value of the degreasing solution is a value determined by the following formula (II) according to the content of silicate. (Y)
The the lower limit was found to be capable of suppressing a decrease in chemical conversion treatability by maintained within a range of an upper limit of 13. y = 6.0x + 9.2 (II) x: value (%) obtained by converting the concentration of silicate compounded in the degreasing solution into the concentration of SiO ₂ (of course, 0.05 ≦ x ≦ 0.30) y: x PH value determined by

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasushi Miyazaki 1-15-1 Nihonbashi, Chuo-ku, Tokyo Japan Parkerizing Co., Ltd. (72) Inventor Yoshikazu Shibata 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Corporation (72) Inventor Masazumi Igarashi 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd.

Claims (2)

[Claims] 1. The following components: (A) 0.05 to 0.30% by weight (however, calculated as SiO ₂ )
And 0.4 to 3.0% by weight of at least one selected from sodium hydroxide, sodium carbonate and sodium hydrogen carbonate, an inorganic builder comprising:
(B) 0.01 to 0.5% by weight of at least one selected from ethylenediaminetetraacetate and nitrilotriacetic acid salt, and 0.1 to 0.5% by weight of polyacrylate and cyclopentane. At least one selected from tetracarboxylic acid salts, polycarboxylic acid salts, hydroxycarboxylic acid salts, and urethanized polyvinyl alcohol,
An organic builder consisting of (C) 0.2 to 0.6% by weight
And a pH value of the alkaline aqueous solution having the following relational expression (I): y ≦ A ≦ 13 (I) [where A is the pH value of the alkaline aqueous solution]. Represents,
y represents the following relational expression (II): y = 6.0x + 9.2 (II) (where x represents the percentage value of the concentration of the silicate compounded in the aqueous solution converted to the SiO ₂ concentration). ) Is a value calculated from. ] A phosphorus-free alkali degreasing solution for low-temperature cleaning of metals, which satisfies 2. The surface active agent, which is 0.18 to 0.
5% by weight of polyoxyethylene polyoxypropylene nonylphenyl ether and 0.02-0.1% by weight of alkyldimethylamine oxide represented by the following formula: (However, R in the above formula represents an alkyl group having 12 to 22 carbon atoms.) The phosphorus-free alkali degreaser for low-temperature metal cleaning according to claim 1.