KR20170028881A - Etching agent and replenishing liquid - Google Patents

Abstract

The steel agent of the present invention is an acidic aqueous solution containing ferrous ions, ferric ions and acetylene group-containing water-soluble compounds. It is preferable that the value of A / B is 0.1 to 2.5 when the concentration of ferrous ion in the etching agent is A weight% and the concentration of ferric ion is B weight%. The replenisher of the present invention is an aqueous solution containing an acetylene group-containing water-soluble compound as a replenisher to be added to the etchant when the etchant is used continuously or repeatedly.

Description

[0001] ETCHING AGENT AND REPLENISHING LIQUID [0002]

The present invention relates to an etching agent for steel and a replenishing solution thereof.

Techniques have been developed to integrate the adherend materials such as steel and resin in a wide range of industries, particularly in the automotive field. For example, Patent Document 1 discloses a method for improving the adhesion between a steel material and an adherend such as a fiber-reinforced plastic, in which a steel material is roughened by etching with a non-oxidizing strong acid aqueous solution and then adhered to the adherend .

Patent Document 1: International Publication No. 2008/146833

However, the inventors of the present invention have found that it is still insufficient to improve the adhesion between the steel material and the adhering material even if the steel material is harmonized with the non-oxidizing strong acid aqueous solution described in Patent Document 1.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and provides an etching agent for steel which can improve the adhesion between a steel material and an adherend, and a replenishing solution thereof.

The etching agent of the present invention is an acidic aqueous solution containing ferrous ions, ferric ions and acetylene group-containing water-soluble compounds as an etching agent for steel. The ratio of the ferrous ion content to the ferric ion content in the etchant is within a predetermined range.

The replenisher of the present invention is an aqueous solution containing an acetylene group-containing water-soluble compound as a replenisher to be added to the etching agent when the etchant of the present invention is used continuously or repeatedly.

When the steel material is treated by the etching agent of the present invention, fine irregularities suitable for adhesion with the adherend are uniformly formed on the surface of the steel material. The steel material treated by the etching agent of the present invention is excellent in adhesion with an adherend such as resin.

1 is a perspective view showing a configuration of a sample for measuring a tensile shear strength.
Fig. 2 is a scanning electron micrograph of the surface of SPCC roughened by the etching agent of the example. Fig.
3 is a scanning electron micrograph of the surface of SPCC roughened by the etchant of the comparative example.
4 is a scanning electron micrograph of the surface of SPCC before the etching process.

<Etching agent>

The steel agent of the present invention is an acidic aqueous solution containing ferrous ions, ferric ions and acetylene group-containing water-soluble compounds. Hereinafter, each component included in the etching agent of the present invention will be described.

(Ferric ion)

The ferric ion is a component which oxidizes the steel material, and can be contained in the etching agent by mixing the ferric ion source. The ferric ion source is not particularly limited and examples thereof include ferric sulfate, ferric chloride, ferric nitrate, ferric hydroxide, and iron (III) ammonium sulfate, Two or more species can be used in combination. Among the ferric ion sources, ferric sulfate, ferric hydroxide, and iron (III) sulfate sulfate are preferable from the viewpoint of properly maintaining the etching rate.

(Ferrous ion)

The etchant of the present invention contains ferrous ions. The etchant contains ferric ions in addition to ferric ions, so that fine irregularities can be formed on the steel material surface. The ferrous ion can be contained in the etching agent by mixing the ferrous ion source. The ferrous ion source is not particularly limited, and examples thereof include ferrous sulfate, ferrous chloride, ferrous nitrate, ferrous hydroxide, and iron (II) ammonium sulfate, Two or more species can be used in combination. Among the ferrous ion sources, ferrous sulfate, ferrous hydroxide, and iron (II) ammonium sulfate are preferable from the viewpoint of forming fine irregularities suitable for improving the adhesion and cost reduction.

(Acetylene group-containing water-soluble compound)

The acetylene group-containing water-soluble compound is a component blended to uniformly form fine irregularities on the surface of the steel material. The acetylene group-containing water-soluble compound is not particularly limited as long as it is a compound having an acetylene group and dissolves in water at 0.01 wt% or more, and for example, a compound having an acetylene group and a hydrophilic group is used. Examples of the hydrophilic group include a hydroxyl group, an amino group, a carboxyl group, and a quaternary ammonium group. Among them, a compound having an acetylene group and a hydroxy group is preferable from the viewpoint of uniformly forming fine unevenness on the surface of a steel material. The hydroxy group of the acetylene group-containing water-soluble compound may be a hydroxy group of the carboxylic acid (that is, the compound containing a carboxyl group is included in a compound containing a hydroxy group). The acetylene group-containing water-soluble compound may be a diene compound or triine compound having two or more acetylene groups in one molecule, or may have two or more hydroxyl groups in one molecule.

Examples of the compound having an acetylene group and an amino group include propargylamine and N, N-diethyl-1-propyne-1-amine. Examples of the compound having an acetylene group and a quaternary ammonium group include N, N, N-trimethyl-2-propyne-1-aminium. Examples of the compound having an acetylene group and a hydroxyl group include 2-butyne-1-ol, 2-pentyn-1-ol, 3- 3-ol, 3-octin-1-ol, 3-phenyl-2-propyne- Ol, 3-nonyn-1-ol, 2-decyn-1-ol, 3,5-dimethyl- 1-ol, 4- (3-aminophenyl) -2-methyl-3-butyn-2-ol and the like having one acetylene group and one hydroxy group; 2,8,8,8-tetramethyl-3,6-nonadin-5-ol, 4,6-nonadecadiyin-1-ol and 10,12-pentacosadin- A compound having two acetylene groups and one hydroxy group; 2-butyne-1,4-diol, 3-hexyne-2,5-diol, 2,5-dimethyl- Diol, 1,4-bis (2-hydroxyethoxy) -2-butyne, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 2,4,7,9- Methyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 3,6- A compound having one acetylene group such as pentyn-1-ol and two hydroxy groups; A compound having one acetylene group such as 2,4-hexadiene-1,6-diol and two hydroxy groups; A compound having one acetylene group and one carboxyl group such as 2-butynic acid, 2-hexynoic acid, 2-heptynic acid, phenylpropiolic acid and the like; Compounds having one acetylene group and two carboxyl groups such as acetylene dicarboxylic acid and salts thereof (such as acetylenedicarboxylic acid potassium); 2,4-pentadecadienic acid, 2,4-pentadecadienic acid, 10,12-heptadecadienoic acid, 2,4-nonadecadienic acid, 2,4-heneicosadic acid, 10,12- And a compound having two acetylene groups and one carboxyl group such as diphosphoric acid. In the present invention, one acetylene group-containing water-soluble compound may be used singly or two or more of them may be used in combination.

(Acid component)

Since the etching agent of the present invention is an acidic aqueous solution, it contains an acid component. The acid component is a component that dissolves a metal (mainly ferrous ion) that is oxidized by ferric ions or the like and eluted from a steel material. Examples of the acid component include hydrohalogenic acids such as hydrofluoric acid, hydrochloric acid (hydrobromic acid), hydrobromic acid and hydroiodic acid, and other inorganic acids such as sulfuric acid, nitric acid, phosphoric acid, perchloric acid and sulfamic acid, and sulfonic acid, Of organic acids. In the present invention, these may be used alone, or two or more of them may be used in combination. Among these acid components, inorganic acid is preferable from the viewpoint of increasing the acid concentration in the etching agent and appropriately maintaining the etching rate. Particularly, sulfuric acid, sulfamic acid and sulfonic acid are preferable from the viewpoint of uniformly forming fine irregularities on the surface of the steel material and from the viewpoint of cost reduction.

(Concentration of each component)

As described above, the etching agent of the present invention includes ferrous ions, ferric ions, an acetylene group-containing water-soluble compound, and an acid component. By setting the concentration of each of these components within a predetermined range, it is possible to uniformly form fine irregularities having a characteristic shape on the steel material surface.

The etching agent of the present invention preferably has a value of A / B of 0.1 to 2.5, more preferably 0.1 to 2.5, More preferably 2.0 to 1.5, and still more preferably 0.2 to 1.5. If the value of the concentration ratio A / B of the ferrous ion and the ferric ion is within the above range, minute unevenness is formed on the surface of the steel material.

The concentration of the ferric ion in the etching agent of the present invention is preferably 0.2 to 20 wt%, more preferably 0.5 to 15 wt%, and still more preferably 1.0 to 10 wt%. If the concentration of the ferric ion is 0.2 wt% or more, the etching rate can be appropriately maintained. On the other hand, if the ferric ion concentration is 20 wt% or less, the dissolution stability of the ferric ion in the etching agent can be maintained and the etching amount can be easily controlled.

The concentration of the ferrous ion is preferably 0.02 to 5 wt%, more preferably 0.03 to 4 wt%, and still more preferably 0.05 to 3 wt%. If the ferrous ion concentration is 0.01% by weight or more, fine irregularities suitable for improving the adhesion can be easily formed. On the other hand, if the ferrous ion concentration is 5 wt% or less, the etching rate can be appropriately maintained.

The concentration of the acetylene group-containing water-soluble compound is preferably from 0.01 to 5% by weight, more preferably from 0.02 to 2% by weight, still more preferably from 0.05 to 1% by weight, from the viewpoint of uniformly forming fine irregularities on the surface of the steel material. to be. When the concentration of the acetylene group-containing water-soluble compound is S% by weight, the concentration ratio S / B of the acetylene group-containing water-soluble compound and the ferric ion is preferably 0.001 to 100, more preferably 0.01 to 10, &Lt; / RTI &gt;

The concentration of the acid component is preferably 0.02 to 1.3 wt%, more preferably 0.03 to 1.0 wt%, and still more preferably 0.05 to 0.8 wt% as the concentration of hydrogen ions. If the hydrogen ion concentration is 0.02% by weight or more, deterioration of the etching rate (dissolution rate) of the steel material can be prevented. On the other hand, when the hydrogen ion concentration is 1.3% by weight or less, the crystal precipitation of the metal salt when the liquid temperature is lowered can be prevented. Further, the workability can be improved, and the cost can be easily reduced.

(Other components)

To the etchant of the present invention, other components may be added within the range not hindering the effect of the present invention. As other components, a surfactant, a compound coordinated to a metal (metal coordination compound), a defoaming agent, and the like can be given. The above-mentioned other component is different from the aforementioned acetylene group-containing water-soluble compound. Examples of the metal coordination compound include a chelating agent such as a carboxylic acid-based chelating agent, a phosphonic acid-based chelating agent, and an amine-based chelating agent, a nitrogen-containing compound, and a sulfur-containing compound. The metal coordination compound is a metal coordination compound which inhibits the elution of metal ions from the surface of the steel to be drained into the metal on the steel surface or accelerates the elution of the metal ions to the metal ions eluted from the surface of the steel, The concavoconvex shape can be controlled. Therefore, by appropriately selecting one or two or more metal coordination compounds, it is possible to control the shape of the irregularities of the surface of the steel material to a shape suitable for improving the adhesion with the adherend. When these other components are added, the concentration thereof is preferably about 0.01 to 10.0% by weight.

The etching agent of the present invention can be easily prepared by dissolving each of the above components in ion-exchanged water or the like.

<Supply amount>

The replenisher of the present invention is an aqueous solution containing an acetylene group-containing water-soluble compound as a replenisher to be added to the etchant when the etchant of the present invention is used continuously or repeatedly. By adding the replenishing liquid, each component ratio of the etchant is properly maintained, so that the effect of the above-described etchant of the present invention can be stably maintained.

In order to adjust the acid concentration of the etching agent or suppress the fluctuation of the acid concentration when adding the replenishing liquid to the etching agent of the present invention, it is preferable that the replenishing liquid is an acidic aqueous solution. Further, in the replenishment solution of the present invention, a component that can be added to the etching agent such as ferric ion, ferric ion, or the like may be further blended. Each component in the replenisher is the same as the component that can be compounded in the above-described etching agent of the present invention.

The concentration of the acetylene group-containing water-soluble compound in the replenishing liquid is appropriately set in accordance with the concentration of the acetylene group-containing water-soluble compound in the etching agent, but from the viewpoint of stably maintaining the effect of the above- Preferably about 7.5% by weight.

&Lt; Using method of etching agent >

Next, a preferable method of using the etching agent of the present invention (hereinafter also referred to as the present method of use) will be described. Steel that can be etched by this method of use is steel such as carbon steel, high tensile steel, low temperature steel and reactor steel, and is used for cold rolled steel (SPCC), hot rolled steel (SPHC), automotive structural hot rolled steel plate ), Hot-rolled high-strength steel sheet material for automobile processing (SPFH), general structural rolled steel used for machining (SS material), and structural steel used for various machines and parts. Since most of these steel materials can be subjected to press working, cutting, and the like, the structure and shape can be freely selected. The steel material according to the present invention is not limited to the above steel materials but includes all steel materials standardized by the Japanese Industrial Standard (JIS) and the International Organization for Standardization (ISO). With this method of use, the removal treatment (including only partial removal) of the steel material by etching, the surface treatment of the steel material, and the like can be performed. Particularly, by performing the surface treatment (micro-etching) of the steel material using the etching agent of the present invention, it is possible to uniformly form fine irregularities having a characteristic shape on the surface of the steel material and to improve the adhesion with an adherend such as resin Can be greatly improved.

(Pretreatment)

In this method of use, mechanical polishing treatment such as degreasing treatment, sandblasting, shot blasting, grinding, barrel working, chemical polishing treatment, and the like are performed on the surface of the steel material before the steel material is treated with the etching agent of the present invention It is also good.

(Etching treatment)

Examples of the method of treating the steel material with the etching agent of the present invention include a method of spraying an etching agent on the surface of the steel material to be treated and a method of immersing the treated steel material into the etching agent. In the case of spraying, it is preferable that the temperature of the etching agent is 20 to 40 캜, and the etching is performed under the spray pressure of 0.05 to 0.3 MPa for 30 to 300 seconds. In the case of immersion, it is preferable that the temperature of the etching agent is set to 30 to 60 캜 and the etching is performed for 60 to 600 seconds.

When the surface of the steel material is treated using the above etching agent, fine irregularities are uniformly formed on the surface of the steel material. The average etching amount (dissolution amount) of the steel material in the depth direction when the above etching agent is used is preferably 0.5 to 10.0 mu m, more preferably 0.75 to 8.0 mu m, as calculated from the weight, specific gravity and surface area of the melted steel material More preferably 1.0 to 5.0 mu m. When the etching amount is 0.5 m or more, fine irregularities having a shape suitable for improving the adhesion can be easily formed. When the etching amount is 10.0 占 퐉 or less, the treatment time can be shortened. The etching amount can be adjusted by the treatment temperature, the treatment time, and the like.

In the present application method, when the steel material is treated using the etching agent, the entire surface of the steel material may be treated, or the surface of the steel material may be partially treated. For example, in the case of forming a composite of a steel material and a resin or the like, the surface of the steel material bonded to the adherend such as resin may be selectively treated. In this method of use, wet etching using other etchants or various dry etching may be used in combination as long as the effects of the present invention described above are not impaired.

(After treatment)

The surface of the steel material after the treatment using the above-mentioned etching agent has an increased surface area and is chemically active. Therefore, when it comes into contact with air, an oxide film tends to be formed quickly. Since this oxide film sometimes hinders adhesion with steel and a resin or the like, acid cleaning is preferably performed as post treatment for the purpose of removing the oxide film. The acid used here is not particularly limited, but when hydrochloric acid or nitric acid is used, the surface of the steel is likely to be re-oxidized. Therefore, the acid used for the post-treatment is preferably selected from acids other than hydrochloric acid and nitric acid. Among them, it is preferable to use polybasic acids such as phosphoric acid, malic acid, citric acid, and tartaric acid from the viewpoint of prevention of re-oxidation.

After the acid cleaning, it is preferable to perform washing with water and drying. If chloride ions remain on the surface of the steel, there is a tendency to promote re-oxidation. Therefore, it is preferable to use ion-exchanged water for washing after pickling. Also, when moisture remains on the surface of steel after washing, it is likely to reoxidize. Therefore, it is preferable to conduct drying by applying sufficient heat after washing.

It is preferable that the steel material that has been dried to such a degree as described above is prevented from deterioration of the bonding property due to the reoxidation before bonding with the adherend such as resin. In order to prevent re-oxidation, the steel material after the etching treatment is preferably stored in a sealed state in which moisture is blocked. Further, for the purpose of preventing reoxidation during storage, the steel material subjected to the etching treatment may be subjected to a rust-preventive treatment. As the rust-preventive agent to be used at this time, generally used amine-based, phosphate, nitrite, chromate, Or the like can be widely used. In addition, when a rust-preventive treatment is carried out with a solvent-based rust inhibitor or an emulsion-based rust-inhibitive agent, a retaining film is formed on the surface of the steel material and adhesion with the adherend tends to be inhibited. Instead of the rust-proofing treatment, or in addition to the rust-preventive treatment, a method of packing and storing the rust-preventive paper impregnated with the vapor-proof rust inhibitor may be used.

&Lt; Use of steel after processing >

The steel material treated by the method of the present invention can be used not only as a material for a steel-resin composite material described later but also as a steel material to which wettability to various solvents is imparted. In addition, the steel material treated by the method of the present invention can be expected to have an adhesion improving effect not only on resin but also on adherends such as glass, metal plating films, inorganic semiconductors, organic semiconductors and ceramics. Further, this method of use can be applied not only to the roughening treatment, but also to the steel material removal treatment (including only partial removal) by etching.

<Steel-resin composite>

Next, a description will be given of a steel-resin composite in which a steel material and a resin composition are integrated as an application example of the steel material processed by the present application method. The steel-resin composite is obtained by treating the steel material by the above-described method of use and then attaching the resin composition to the treated surface. By treating the steel material with the etching agent of the present invention, irregularities suitable for improving the adhesion between the steel material and the resin composition are uniformly formed on the surface of the steel material, so that the adhesion between the steel material and the resin composition can be improved. The method for adhering the resin composition to the surface of the steel material treated by the present method is not particularly limited and may be injection molding, Molding (RIM molding), and rim molding (LIM molding). In the case of producing a composite comprising a steel material-resin composition film coated with a resin composition film on the surface of a steel material, a coating method in which a resin composition is dissolved or dispersed in a solvent, or other various coating methods can be employed . Examples of other coating methods include baking coating, electrodeposition coating, electrostatic coating, powder coating, ultraviolet curing coating, and the like. The molding conditions of the above-mentioned molding methods may be known conditions depending on the resin composition.

The resin composition that can be used for the steel-resin composite is not particularly limited as long as it can be adhered to the surface of the steel by the above-described molding methods, and the thermoplastic resin composition and the thermosetting resin composition can be selected according to the use.

(Thermoplastic resin composition)

When a thermoplastic resin composition is used, examples of the thermoplastic resin as the main component include polyamide resins such as polyamide 6 and polyamide 66, polyethylene resins, polypropylene resins, acrylonitrile / styrene copolymer resins, acrylonitrile / butadiene / Styrene copolymer resin, polyvinyl chloride resin, polycarbonate resin, polyacetal resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyethylene naphthalate resin, polyphenylene sulfide resin, liquid crystalline polyester resin, polyimide resin, Polyvinyl acetate resin, modified polyphenylene ether resin, polyether sulfone resin, amorphous polyarylate resin, aromatic polyether ketone resin, ethylene-acetic acid Vinyl copolymerization water , There may be mentioned an ethylene-acrylic acid copolymer resin, ethylene-methacrylic acid copolymer resin or the like, such as a combination of two or more thereof.

The thermoplastic resin composition that can be used may be a composition composed of the above-described thermoplastic resins, and may contain various conventional inorganic and organic fillers, flame retardants, flame retardants, and antistatic agents to the above-mentioned thermoplastic resins to such an extent that the effects of the present invention are not impaired. A composition containing an additive such as an ultraviolet absorber, a heat stabilizer, a light stabilizer, a colorant, carbon black, a processing aid, a nucleating agent, a releasing agent, a plasticizer or a fibrous reinforcement may be added.

(Thermosetting resin composition)

When a thermosetting resin composition is used as the resin composition, examples of the thermosetting resin as the main component include phenol resin, epoxy resin, urea resin, melamine resin, unsaturated polyester resin, polyimide resin, diallyl phthalate resin, A resin, a cyanate resin, a silicone resin, or a combination of two or more of these.

The thermosetting resin composition that can be used may be a composition made of the above-mentioned thermosetting resin, and various conventional inorganic and organic fillers, flame retardants, flame retardants, and flame retardants may be added to the thermosetting resins listed above to the extent that the effects of the present invention are not impaired. A composition prepared by adding additives such as an ultraviolet absorber, a heat stabilizer, a light stabilizer, a colorant, carbon black, a processing aid, a nucleating agent, a releasing agent, a plasticizer and a fiber reinforcing agent.

(Other resin composition)

Other resin compositions that can be used include various resin compositions such as a photo-curable resin composition including an acrylic resin and a styrene resin, and a reaction curable resin composition including a rubber and an elastomer.

The above-described steel-resin composite is suitably used for manufacturing various machine parts such as parts for electronic equipment, parts for home electric appliances, parts for transportation machines, and the like, and more particularly, Parts for household appliances, parts for medical devices, structural parts for vehicles, and components for vehicle mounting.

Example

Next, examples of the present invention will be described together with comparative examples. The present invention is not limited to the following examples.

<Treatment by Etching Agent>

As a test substrate, a dull finish cold rolled steel sheet (Shinryttsu Sumikin) having a width of 20 mm, a length of 30 mm and a thickness of 2.3 mm was prepared, immersed in acetone as a pretreatment, and subjected to degreasing treatment for 15 minutes while applying ultrasonic waves . Next, the test substrates were immersed in the respective etching agents shown in Tables 1 and 2, and etching was performed at 50 占 폚 by adjusting the etching time such that the etching amount of iron became 2.0 占 퐉. The remainder of the blending components of the respective etching agents shown in Tables 1 and 2 is ion-exchanged water, and the% of the concentration is all% by weight.

After the etching, the etched surface of the test substrate was immersed in a 5% tartaric acid solution at 25 캜 for 15 seconds, washed with ion-exchanged water, dehydrated, and then dried in an oven at 120 캜 for 10 minutes.

<Tensile Shear Strength Measurement Test>

The surface of the test substrate 1 after the above treatment was laminated with the FRP plate 3 (manufactured by Nippon Denshoku Industries Co., Ltd.) through an epoxy-impregnated glass cloth prepreg 5 (5 mm x 10 mm x thickness 0.1 mm; 10 mm in width, 30 mm in length and 1.6 mm in thickness) was laminated and fixed with a polyimide heat-resistant tape, and then heated in an oven at 160 캜 for 90 minutes to cure the prepreg to obtain a sample for tensile shear strength measurement shown in Fig. 1 .

The steel sheet portion and the FRP portion of the sample for measurement were clamped and tensile shear strength of the joint portion was measured using Autograph (manufactured by Shimadzu Corporation, model number: AGS-X10kN). The results are shown in Tables 1 and 2.

Figs. 2 to 4 are photographs of a surface of SPCC observed with a scanning electron microscope (SEM) (accelerating voltage 20 kV, sample inclination angle 45 deg., Magnification 3500 times). Fig. 2 shows the results obtained after the treatment with the etching agent of Example 9, Fig. 3 shows the results after the treatment with the etchant of Comparative Example 8, and Fig. 4 shows the SPCC before treatment (Comparative Example 8). 2 and 3, in which the etching treatment was performed, as compared with the surface of Fig. 4 where the etching treatment was not carried out, the surface of the SPCC was uneven and the surface area was increased. In contrast to FIG. 2 and FIG. 3, in FIG. 3, mountain-like convex portions are formed in a mesh shape, and only smooth convex and concave portions are formed between mountain-like convex portions. On the other hand, 2, it can be seen that irregularities which are sharply entered between the mountain-like convex portions are formed. It is considered that by performing the surface treatment with the etching agent of the present invention, such a characteristic irregular shape is uniformly formed on the surface of the steel material, so that a high anchor effect (projection effect) is exhibited and the adhesion with the adherend is greatly improved .

When the results of Table 1 and Table 2 were examined in detail, it was found that when treated with the etching agents of Comparative Examples 1 to 4 and Comparative Example 7 which did not contain any of the ferrous ions, ferric ions, and acetylene group- , And the tensile shear strength of the joint was about 20 MPa (Table 2). Also in the case of Comparative Example 5 in which the ratio A / B of the ferrous ion concentration (A) to the ferric ion concentration (B) is less than 0.1 and the case where it is treated with the etching agent of Comparative Example 6 in which A / B is larger than 2.5, The shear strength was about 20 MPa. On the other hand, in Examples 1 to 9 (Table 1) using an etchant containing a ferrous ion, a ferric ion, and an acetylene group-containing water-soluble compound and having an A / B ratio within a predetermined range, all tensile shear strength Is about 30 MPa or more, and a high adhesion strength of 1.5 times or more as compared with Comparative Examples 1 to 7 can be obtained.

Claims (7)

As an etching agent for steel,
An acidic aqueous solution containing ferrous ion, ferric ion and acetylene group-containing water-soluble compound,
Wherein an A / B value is 0.1 to 2.5, wherein the concentration of the ferrous ion is A% by weight and the concentration of the ferric ion is B% by weight. The etching agent according to claim 1, wherein the acetylene group-containing water-soluble compound is a compound having an acetylene group and a hydroxy group. The method of claim 1 or 2, wherein the concentration of the ferric ion is 0.2 to 20 wt%
Wherein the concentration of the acetylene group-containing water-soluble compound is 0.01 to 5% by weight. The etchant according to any one of claims 1 to 3, wherein the acid concentration of the etchant is 0.02 to 1.3 wt% in terms of hydrogen ion concentration. The etchant according to any one of claims 1 to 4, wherein the concentration of the ferrous ion is 0.02 to 5 wt%. A replenishment liquid which is an aqueous solution containing an acetylene group-containing water-soluble compound as a replenisher to be added to the etchant when the etchant according to any one of claims 1 to 5 is used continuously or repeatedly. The replenishing liquid according to claim 6, wherein the replenishing liquid is an acidic aqueous solution.

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