JPH11264075A - Tin-plated steel surface treated can and surface treatment of tin-plated steel can - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the tin-plated steel surface treated can giving an extremely excellent corrosion resistance and coating adhesion on the surface of the steel can. SOLUTION: A coating weight of the org. compd. in an org.-inorg. composite film obtained by coating a film consisting of an org. compd. consisting essentially of carbon and an inorg. compd. and having 5-1000 nm thickness on a tin-plated surface obtained by processing a tin-plated steel sheet by a surface coating ratio of >=90% is kept in 5-300 mg/m<2> in terms of the carbon and the coating weight of the inorg. phosphorus compd. is kept in 1-60 mg/m<2> in terms of phosphorus.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel tin-plated steel surface treatment which has a coating excellent in corrosion resistance and paint adhesion on a tin-plated surface of a tin which is made by processing a tin-plated steel plate. The present invention relates to a surface treatment method for a can and a tin-plated steel can.

[0002]

2. Description of the Related Art Conventionally, a drawn and ironed can is known as a kind of two-piece can. This drawn and ironed can is drawn and then ironed.
Is generally called a DI can. DI material is a metal material with excellent workability.
Tin plated steel and aluminum alloys are used. Currently, drawn ironing cans using tin-plated steel sheets are widely used for applications such as carbonated beverages and oolong tea.

[0003] Generally, a drawn and ironed can is generally coated with a paint on a can body after processing. As a pre-treatment, a surface treatment is performed to improve the corrosion resistance of the can body and the adhesion to the coating film. I have. Regarding the surface treatment liquid for steel DI cans, see, for example, Japanese Patent Application Laid-Open No. 1-10028, filed by the same applicant as the present application.
No. 1 is disclosed. The present invention relates to phosphate ions 1 to 50 g / L, oxyacid ions 0.2 to 20.0 g / L,
It is a coating solution for metal surface treatment containing 0.01 to 5.0 g / L of tin ions and 0.01 to 5.0 g / L of condensed phosphate ions and having a pH of 2 to 6. Further, Japanese Patent Application Laid-Open No. Hei 6-1 / 1992, in which the same applicant is concerned as having improved operability.
No. 73024. By treating steel DI cans with the chemical conversion solution of these inventions,
A phosphate film having excellent corrosion resistance can be formed on the surface of a steel DI can.

On the other hand, metal surface treatment methods for imparting corrosion resistance and adhesion using a water-soluble polymer include:
JP-A-61-91369, JP-A-1-17240
6, JP-A-1-177379, JP-A-1-177379
The inventions disclosed in JP-A-177380, JP-A-2-608 and JP-A-2-609 are exemplified. The invention of these prior arts is a method of treating a metal surface with a solution containing a derivative of a useful polyvalent phenol compound. However, it is difficult to form a sufficiently stable film on the surface by the methods disclosed in these publications,
Sufficient performance (corrosion resistance) cannot be obtained. And, the processing method including the derivative of the polyvalent phenol compound is improved,
The invention of Japanese Unexamined Patent Publication No. Hei 4-187782 involving the same applicant also has a problem that sufficient adhesion cannot be obtained with some paints.

[0005] Even in the prior art, since the corrosion resistance of the inner surface of the can is not always sufficient, a two-coat, two-bake system in which the inner surface is coated twice is actually employed. In recent years, it has been desired to greatly reduce the manufacturing cost of cans, and attempts have been made to make the inner surface coating only once. At this time, a surface treatment which is much more excellent in corrosion resistance than before has been required. The applicants have proposed Japanese Patent Application Laid-Open No. 9-31403 in which the corrosion resistance is improved. The invention of this application relates to tinplate DI containing phosphate ions, condensed phosphate ions and a phenolic water-soluble polymer.
The present invention relates to a surface treatment composition for a can and a surface treatment method. However, even in this method, one coat does not always provide sufficient corrosion resistance.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve these problems of the prior art. Specifically, the present invention relates to tin which has extremely excellent corrosion resistance and paint adhesion on the surface of a steel can. An object of the present invention is to provide a surface treatment method for a plated steel surface-treated can and a tin-plated steel can.

[0007]

Means for Solving the Problems The present inventors have intensively studied means for solving the problems of the prior art, and as a result, a specific film was formed on the surface of a can obtained by processing a tin-plated steel sheet. A steel can having a thick organic-inorganic composite coating with a specific adhesion amount and covering the surface with the composite coating in a specific range ratio and a method for treating the steel can have been newly discovered, and the present invention has been completed. Was. That is, the present invention provides a can obtained by processing a tin-plated steel sheet and performing a surface treatment on a tin-plated surface, comprising an organic compound containing carbon as a main component and an inorganic phosphorus compound, and having a thickness of 5 to 5. 1000nm
Organic film coated with a film having a surface coverage of 90% or more
It has an inorganic composite film, and the amount of organic compound attached is 5 to 300 mg / m ² as carbon and the amount of inorganic phosphorus compound attached is 1 to 60 mg / m ² as phosphorus. It relates to a tin-plated steel surface treatment can. The organic compound is preferably a polymer represented by the following general formula.

[0008]

Embedded image

However, in the formula (I), X ¹ and X ²
Each independently represents a hydrogen atom, a C ₁ -C ₅ alkyl group or a C ₁ -C ₅ hydroxyalkyl group,
Y ¹ and Y ² each independently represent a hydrogen atom,
Alternatively, it is a Z group represented by the following formula (II).

[0010]

Embedded image

However, in the formula (II), R ¹ and R ² each independently represent a hydrogen atom, a C ₁ -C ₁₀ alkyl group,
Or Z represents a member selected from C _{1 to} C ₁₀ hydroxyalkyl groups, and each of the Z groups bonded to the benzene ring of the polymer molecule may be different from each other; or The average value of the Z group substitution number of each benzene ring in the polymer molecule may be 1.0.
It is as follows.

Further, the inorganic phosphorus compound is preferably at least one selected from a phosphoric acid compound, a condensed phosphoric acid compound, a zirconium phosphate compound and titanium phosphate. Further, a phosphate ion of 0.5 to 30 g / L,
0.1 to 20 g / L of condensed phosphate ion or 0.0
5 to 10 g / L complex fluoride ion and 0.1 to 40 g
/ L of the water-soluble polymer of the above general formula (I) [provided that the average number of substitutions of the Z group on each benzene ring in the polymer molecule is 0.1.
2 to 1.0, and n represents an average degree of polymerization of 2 to 50. And a surface treatment liquid having a pH of 2.2 to 4.5 is heated to 35 to 65 ° C., spray-treated for 5 to 60 seconds, and then washed with water and heated and dried. Thereby, a target steel processing can can be obtained.

Hereinafter, the tin-plated steel surface treatment can of the present invention will be described in detail. The can body in the present invention is a can body obtained by processing a tin-plated steel sheet. The processing method for forming the can body includes drawing, drawing and ironing, stretch drawing, and the like. Although not particularly limited, the surface treatment of the present invention is particularly effectively applied to drawing. It is an ironing can. The tin-plated steel sheet used is
It is not particularly limited as long as it can withstand industrial drawing and ironing and can make cans.

In the present invention, an organic-inorganic composite film must be present as an essential component on the surface of the can body. The surface treatment liquid and the surface treatment method for forming the organic-inorganic composite film on the surface are not particularly limited. The organic-inorganic composite film contains carbon as a main component. It consists of an organic compound and an inorganic phosphorus compound. The adhesion amount of the organic compound in the composite film is extremely important for determining the corrosion resistance. The amount of organic compound attached is 5 to 5% as carbon.
300 mg / m ² , preferably 20-100 mg
/ m ² . If the amount is less than 5 mg / m ² , sufficient corrosion resistance cannot be obtained. Further, if it exceeds 300 mg / m ² , there is no problem in performance, but it is not preferable because it increases the cost. The inorganic compound in the composite coating is an inorganic phosphorus compound, and the amount of the phosphorus compound is in the range of 1 to 60 mg / m ² , preferably 4 to 20 mg / m ² as phosphorus.
If the amount is less than 1 mg / m ² , sufficient corrosion resistance cannot be obtained. If it exceeds 60 mg / m ² , there is no problem in performance, but it is not economically preferable because the cost is increased.
In the present invention, titanium, zirconium, fluoride and the like can also be constituents of the film.

The thickness of the organic-inorganic composite film of the present invention is 5 to 5.
In the range of 1000 nm, preferably 20-100 n
m. If the thickness is less than 5 nm, excellent corrosion resistance cannot be obtained. If it exceeds 1000 nm, the color tone may be impaired. The coverage of the surface of the composite coating must be 90% or more. If the coverage is less than 90%, the corrosion resistance is not sufficient.

Next, a method for measuring the amount of carbon adhering, the amount of phosphorus adhering, the coverage of the film and the film thickness specified in the present invention will be described. The amount of carbon attached is measured using a commercially available surface carbon analyzer. First, the steel surface-treated can of the present invention is cut into an appropriate size (about 20 to 50 cm ² ) to obtain a sample. The surface carbon analyzer is based on the principle of raising the temperature of a sample, oxidizing and gasifying carbon present on the surface, and quantifying the gas by IR (infrared absorption). The measurement condition may be any condition that oxidizes and gasifies carbon on the surface, but it is generally preferable to measure under conditions of about 400 ° C. for about 5 minutes. The amount of phosphorus attached is quantified by a commercially available fluorescent X-ray analyzer. A plurality of samples with known amounts of phosphorus attached and having different amounts of adhesion are measured, and an intensity-adhesion calibration curve is created from the intensity at this time. Under the same conditions, the tin-plated steel can of the present invention is cut into an appropriate size (about 3 cm) and measured. This measured intensity is converted to the amount of phosphorus attached based on the above-mentioned calibration curve.

The coverage is determined by a commercially available XPS (X-ray photoelectron spectroscopy) device. XPS is a device that excites a sample with X-rays in an ultra-high vacuum (10 ⁻⁵ Pa or less) and analyzes photoelectrons emitted at this time. From the photoelectron intensity and the sensitivity coefficient, the ratio of atoms existing on the surface can be calculated. The quantitative calculation method has already been established and is commercially available as a program. It should be noted in the actual measurement that since the sample exposed to the atmosphere is always contaminated, even if the sample cleaned in the atmosphere is analyzed by XPS, contaminants such as carbon are detected on the outermost surface. It is a point. In order to remove this effect, the calculation of the coverage defined in the present invention is performed by slightly sputtering the outermost surface of about 2 nm with argon. That is, using a commercially available argon sputtering gun attached to the XPS analyzer, the surface was sputtered by 2 nm to remove contaminants, and then the surface was excited by X-rays to analyze photoelectrons. After excitation with X-rays, an analysis called wide scan is performed, and first, qualitative determination of atoms existing on the surface is performed. Usually, the elements detected in the steel processing can of the present invention are mainly carbon, oxygen, phosphorus, tin, and iron. Quantitative calculation was performed on the elements measured in qualitative terms, and A and B, which are the atomic percentages of tin and iron in the metallic state,
Is calculated. From this, the coverage was calculated by the following equation (III). Coverage = 100− (A + B) (III)

The thickness of the organic-inorganic composite film is measured using the above-mentioned argon sputtering gun. Samples having a known film thickness (measured by a transmission electron microscope or the like) and different film thicknesses are measured a plurality of times by argon sputtering-photoelectron analysis. The coating was defined as having existed until the coating ratio reached 40 atomic%, and a calibration curve of the integrated time of sputtering and the thickness of the coating required for this was created. Then, the steel processing can of the present invention is analyzed, and the film thickness is calculated from the integrated time of sputtering until the coverage becomes 40 atomic% and the calibration curve.

The organic compound used in the present invention must have a structure that satisfies these requirements in consideration of corrosion resistance and food hygiene in order to be used for beverage cans. Preferred examples of the organic compound include a polymer represented by the above formula (I). However, in the formula (I), X ¹ and X ² are
Independently of one another, represent a hydrogen atom, C ₁ -C ₅ alkyl or C ₁ -C ₅ hydroxyalkyl group, Y ¹
And Y ² are each independently a hydrogen atom or a Z group represented by the above formula (II). However,
In the formula (II), R ¹ and R ² are each independently
A hydrogen atom, a C ₁ -C ₁₀ alkyl group or a C ₁ -C ₁₀ hydroxyalkyl group), and each of the Z groups bonded to the benzene ring of the polymer molecule is The average value of the Z group substitution number of each benzene ring in the polymer molecule may be 1.0 or less. Next, the reasons for limiting the structure of these compounds will be described.

In X ¹ and X ² , if C ₆ or more, the resin becomes bulky and causes steric hindrance and does not form a film excellent in dense corrosion resistance. Therefore, X ¹ and X are each independently a hydrogen atom, C ₁ to A C ₅ alkyl group or a C ₁ -C ₅ hydroxyalkyl group. Y ¹ and Y
² are each independently a hydrogen atom or a formula (I
Z group represented by I). In the formula (II), R ¹ ,
In R ^2, the functional group is a C ₁₁ or higher Baruki - since only coating the corrosion resistance becomes coarse becomes lower, R ^1, R ² are each, independently of one another, a hydrogen atom, C ₁ -C ₁₀ alkyl or C ₁ ~ One member selected from C ₁₀ hydroxyalkyl groups. Each of the Z groups attached to the benzene ring of the polymer molecule may be different from one another or may be the same as the other. The average number of Z group substitutions on each benzene ring in the polymer molecule is 1.0 or less. For example,
If 10 Zs are introduced into a polymer having n of 10 (20 aromatic rings), if the introduction ratio is 1 or more, the bulkiness is too large and the film becomes coarse and the corrosion resistance is reduced. The value was 1.0 or less.

The inorganic phosphorus compound which is an inorganic component applied in the present invention is a very important component for imparting corrosion resistance. Preferred compounds are one or more selected from phosphoric acid compounds, condensed phosphoric acid compounds, zirconium phosphate and titanium phosphate.

Next, with respect to the process for producing the tin-plated steel processing can of the present invention, a production example of a steel drawn and ironed can as a preferred example will be described. The process of producing a drawn ironing can made of steel conforms to the known DI can production process. That is, a circular plate called a blank is punched from a tin-plated steel plate (coil), and the blank is drawn into a cup shape. Next, the cup is redrawn and the side wall is ironed to form a can. At this time, various lubricants are used in order to facilitate the drawing and ironing, and the formed can body is in a state where the lubricant is attached. For this reason, it is difficult to form a film uniformly on the surface as it is. Therefore, first, a cleaning process is performed for the purpose of removing the lubricant and abrasion powder generated on the surface during molding. As the cleaning agent, an alkaline cleaning agent can be used and is not particularly limited. The washed can body surface is rinsed with water, and a surface treatment is performed for the purpose of forming a film on the surface. The surface treatment method for forming the organic-inorganic composite film of the present invention is not particularly limited, but since the surface treatment has been a facility that uses an aqueous chemical treatment solution for a long time, existing facilities are used as they are. A method of treating with a water-based surface treatment liquid is industrially desirable.

Next, a surface treatment liquid as a preferred example for forming the organic-inorganic composite film of the present invention will be outlined. To form the organic compound as a film, a water-soluble polymer can be used. Phosphoric acid, condensed phosphoric acid or complex fluoride is allowed to coexist with the mixture to adjust the pH to a value at which the water-soluble polymer is easily precipitated. This treatment liquid is brought into contact with a can. Phosphoric acid etches the surface of the material, causing an increase in pH at the interface. As a result, the coexisting water-soluble polymer and inorganic phosphorus compound are deposited on the surface to form a film. In order to facilitate the deposition of a film, a treatment liquid in which phosphoric acid and fluorozirconic acid (H ₂ ZrF ₆ ) or fluorotitanic acid (H ₂ TiF ₆ ) coexists is also useful. The surface-treated cans are rinsed with water, and the unreacted ones are removed from the surface. Further, it is rinsed with pure water or the like and further dried to obtain the steel processing can of the present invention. In addition, depending on the drying temperature, the polymer can be further polymerized on the surface. When higher corrosion resistance is obtained, the drying temperature may be increased (180 ° C. or higher) to increase the degree of polymerization on the surface. When the degree of polymerization is increased by heating, the degree of polymerization n is a value (2 to 50) in the following surface treatment solution.
Be larger. Further, at this time, the number of Z group substitutions becomes smaller than the value (0.2 to 1.0) in the surface treatment solution because the Z group is eliminated. Carbon adhesion (attributable to organic compounds)
In addition, the phosphorus adhesion amount (attributable to the inorganic phosphorus compound), the coverage and the film thickness can be adjusted by the concentration of the water-soluble polymer in the treatment liquid, the concentration of the inorganic phosphorus compound, the treatment temperature, the treatment time, and the like.

The preferred treatment method is 0.5 to 30.
g / L phosphate ion, 0.1-20 g / L condensed phosphate ion or 0.05-10 g / L complex fluoride ion, and 0.1-40 g / L of the above general formula (I) A water-soluble polymer represented by the formula [provided that the average value of the number of Z groups substituted on each benzene ring in the polymer molecule is 0.2 to 1.0;
And n represents an average degree of polymerization of 2 to 50. And a surface treatment solution having a pH of 2.2 to 4.5 at 35 to 65 ° C.
, And spray-treated for 5 to 60 seconds, followed by washing with water and heating and drying once. The reasons for limiting the conditions in this method will be described below. If the concentration of phosphate ions is 0.5 g / L or less, the reactivity is poor and no film is formed. On the other hand, if the concentration exceeds 30 g / L, the cost increases and there is an economic problem. If the condensed phosphate ion concentration is less than 0.1 g / L, the film will not grow sufficiently. On the other hand, if the concentration exceeds 20 g / L, the stability of the processing solution is deteriorated, which causes a problem. The complex fluoride ion is a component that promotes the deposition of the film, and the concentration thereof is 0.0
If it is less than 5 g / L, the phosphate compound film will not grow sufficiently. On the other hand, if the concentration exceeds 10 g / L, the stability of the processing solution becomes poor, which is a problem. When the concentration of the water-soluble polymer is 0.
If it is less than 1 g / L, a sufficient amount of carbon adhered cannot be obtained.
If it exceeds 40 g / L, the cost will increase and the economy will be problematic. If the pH of the treatment liquid is less than 2.2, the film does not grow sufficiently. On the other hand, when the pH exceeds 4.5, the stability of the processing solution is deteriorated, and a problem of generation of precipitation occurs. Processing temperature is 35
If the temperature is lower than ℃, the film does not grow sufficiently. Processing temperature is 65 ° C
If it exceeds, there is a problem in the stability of the processing solution. If the treatment time is less than 5 seconds, the film will not grow sufficiently. Although there is no particular problem if the time exceeds 60 seconds, the processing step becomes longer and an extra space is required.

[0025]

EXAMPLES Several examples of the steel surface-treated can of the present invention will be described below, and its usefulness will be shown in comparison with comparative examples.

[Method of Making Steel Can] A steel DI can made by squeezing and ironing a tin-plated steel sheet was prepared using a commercially available cleaning agent (registered trademark, Fine Cleaner 4493, manufactured by Nippon Parkerizing Co., Ltd.). % Aqueous solution at 50 ° C. for 40 seconds, and then washed with water and cleaned, and then sprayed with the surface treatment solution described in Examples.
Treatment, then washed with tap water, and further 3000,
After spraying with deionized water of 000 Ωcm or more for 10 seconds, drying was performed in a hot air drying oven at 180 ° C. for 2 minutes.

[Measurement Method of Attached Amount] The attached amount of the organic-inorganic composite coating on the steel can treated as described above was quantified. The amount of carbon attached was determined using a commercially available surface carbon analyzer. The sample size is 32cm ² and the measurement condition is 40
0 ° C.-5 minutes. The amount of phosphorus attached was quantified using a commercially available fluorescent X-ray analyzer. The sample size was φ3 cm.

[Coverage Ratio and Film Thickness] The state of the organic-inorganic composite film of the steel can treated as described above was analyzed using a commercially available XPS (X-ray photoelectron spectroscopy) apparatus.
The outermost surface was sputtered by 2 nm and qualitative analysis was performed. The elements detected at this time were quantitatively calculated, and the coating rate was calculated according to the above-mentioned formula (III). In addition, a commercially available argon sputtering gun was attached to the XPS analyzer, and the film was broken and removed by sputtering. The film thickness was calculated from the sputtering time at this time by the method described above.

[Evaluation Methods] The corrosion resistance and adhesion were evaluated by the following methods.

Red rust test In the red rust test, a surface-treated can was placed in hot tap water at 65 ° C for 3 hours.
Evaluation was made based on the degree of rust generation after immersion for 0 minutes. No occurrence of red rust is indicated by “○”, partial occurrence is indicated by “△”, and entire occurrence is indicated by “×”.

Iron Exposure Corrosion of a tin-plated steel surface treatment can often starts from an iron exposed portion caused by DI processing. Therefore, corrosion resistance can be confirmed by measuring the iron exposed portion. The measurement of the iron exposed part (IEV) was based on US Patent 4332646.
Generally, the lower the IEV value, the better the corrosion resistance.

Eluted Metal Concentration A commercially available coffee beverage was poured into a surface-treated can (unpainted state) and left at 50 ° C. for 48 hours. Thereafter, the concentration of metal ions eluted in the coffee beverage was quantified by commercially available atomic absorption. The lower the elution concentration, the better.

Cathodic electrolysis test An inner surface paint for a can was applied to a surface-treated can to a thickness of 5 µm (one coat). The paint adhesion of the paint can was evaluated by a cathodic electrolysis test. The cathodic electrolysis test was conducted according to
0453 was applied. The surface after the test was observed to observe the state of the blister. "B" indicates that no blisters were generated, "B" indicates that the blisters were 2 mm or less, "B" indicates that blisters were 2 to 5 mm in diameter, and "X" indicates that blisters were 5 mm or more.

Example 1 A treatment was performed using the following surface treatment liquid. The amount of the organic-inorganic composite film formed, the coverage, and the film thickness are shown below. Surface treatment solution 1 75% phosphoric acid (H ₃ PO ₄ ) 3.0 g / L Sodium pyrophosphate (Na ₄ P ₂ O ₇ .10H ₂ O) 3.0 g / L Water-soluble polymer solid content 2.0 g / L pH 3 0.0 (adjusted with sodium hydroxide) water-soluble polymer 1 n = 5 X ¹ , X ² = hydrogen Y ¹ , Y ² = —CH ₂ N (CH ₃ ) ₂ introduction rate = 0.25 Other surface treatment temperature: 60 ° C. Surface treatment time: 20 seconds Carbon adhesion amount: 20 mg / m ² Phosphorus adhesion amount: 4 mg / m ² Coverage: 90% Film thickness: 15 nm

Example 2 A treatment was performed using the following surface treatment liquid. The amount of the organic-inorganic composite film formed, the coverage, and the film thickness are shown below. Surface treatment liquid Hydrofluoric acid (HF) 0.05 g / L Fluorozirconic acid (H ₂ ZrF ₆ ) 0.1 g / L 75% phosphoric acid (H ₃ PO ₄ ) 0.1 g / L Water-soluble polymer solids 0.4 g / L pH 2.7 (adjusted with aqueous ammonia) Water-soluble polymer 2 n = 5 X ¹ , X ² = —C ₂ H ₅ Y ¹ , Y ² = —CH ₂ N (CH ₂ CH ₂ OH) ₂ introduced Ratio = 0.5 Other surface treatment temperature: 50 ° C. Surface treatment time: 30 seconds Carbon adhesion amount: 10 mg / m ² Phosphorus adhesion amount: 2 mg / m ² Coverage: 92% Film thickness: 8 nm

Example 3 A treatment was performed using the following surface treatment liquid. The amount of the organic-inorganic composite film formed, the coverage, and the film thickness are shown below. Surface treatment solution 3 75% phosphoric acid (H ₃ PO ₄ ) 5.0 g / L Sodium pyrophosphate (Na ₂ H ₂ P ₂ O ₇ ) 4.0 g / L Water-soluble polymer solid content 9.0 g / L pH 3 0 (adjusted with sodium hydroxide) water-soluble polymer 3 n = 15 X ¹ , X ² = —C ₂ H ₅ Y ¹ , Y ² = —CH ₂ N (CH ₂ CH ₂ OH) ₂ introduction rate = 0. 6 Other surface treatment temperature: 60 ° C Surface treatment time: 45 seconds Carbon adhesion amount: 50 mg / m ² Phosphorus adhesion amount: 10 mg / m ² Coating rate: 95% Film thickness: 50 nm

Example 4 A treatment was performed using the following surface treatment liquid. The amount of the organic-inorganic composite film formed, the coverage, and the film thickness are shown below. Surface treatment solution 4 75% phosphoric acid (H ₃ PO ₄ ) 5.0 g / L Sodium acid pyrophosphate (Na ₂ H ₂ P ₂ O ₇ ) 4.0 g / L Sodium tripolyphosphate (Na ₅ P ₃ O ₁₀ ) 1.2 g / L Water-soluble polymer solid content 10.0 g / L pH 3.2 (adjusted with sodium hydroxide) Water-soluble polymer 4 n = 15 X ¹ , X ² = hydrogen Y ¹ , Y ² = -CH ₂ N (CH ₂ OH) ₂ introduction rate = 0.5 Other surface treatment temperature: 60 ° C. Surface treatment time: 50 seconds Carbon adhesion amount: 100 mg / m ² Phosphorus adhesion amount: 20 mg / m ² Coating rate: 98% Film thickness: 100 nm

Example 5 A treatment was performed using the following surface treatment liquid. The amount of the organic-inorganic composite film formed, the coverage, and the film thickness are shown below. Surface treatment solution 5 75% phosphoric acid (H ₃ PO ₄ ) 3.0 g / L sodium pyrophosphate (Na ₄ P ₂ O ₇ · 10H ₂ O) 3.0 g / L Water-soluble polymer solid content 2.0 g / L pH 3 5 (adjusted with sodium hydroxide) water-soluble polymer 5 n = 20 X ¹ , X ² = hydrogen Y ¹ , Y ² = —CH ₂ N (CH ₂ CH ₂ CH ₂ OH) ₂ introduction rate = 0.75 and others Surface treatment temperature: 50 ° C Surface treatment time: 20 seconds Carbon adhesion amount: 15 mg / m ² Phosphorus adhesion amount: 4 mg / m ² Coverage: 91% Film thickness: 7 nm

Comparative Example 1 A treatment was performed using the following surface treatment liquid. The amount of the organic-inorganic composite film formed, the coverage, and the film thickness are shown below. Surface treatment solution 7 75% phosphoric acid (H ₃ PO ₄ ) 0.5 g / L Water-soluble polymer solid content 1.0 g / L pH 6.0 (adjusted with ammonia water) Water-soluble polymer 6 n = 10 X ¹ , X ² = hydrogen Y ¹ , Y ² = -CH ₂ N (CH ₂ CH ₂ CH ₂ OH) ₂ introduction rate = 0.75 Other surface treatment temperature: 40 ° C. Surface treatment time: 5 seconds Carbon adhesion amount: 2 mg / m ² phosphorus adhesion amount: 0.2 mg / m ² coverage: 70% film thickness: 0.3 nm

Comparative Example 2 The following surface treatment liquid was applied and dried without washing with water.
The amount of the organic-inorganic composite film formed, the coverage, and the film thickness are shown below. Surface treatment liquid 8 75% phosphoric acid (H ₃ PO ₄ ) 0.01 g / L Water-soluble polymer solid content 0.02 g / L pH 7.0 (adjusted with aqueous ammonia) Water-soluble polymer 1 n = 5 X ¹ , X ² = hydrogen Y ¹ , Y ² = -CH ₂ N (CH ₃ ) ₂ introduction rate = 0.25 Other carbon adhesion amount: 20 mg / m ² phosphorus adhesion amount: 4 mg / m ² coverage: 80% Film thickness Sa: 15 nm

Comparative Example 3 A commercially available tin phosphate-based surface treatment solution (registered trademark, Parphos K)
5100: manufactured by Nippon Parkerizing Co., Ltd.) and a can spray treatment was performed at 50 ° C. for 20 seconds. The attached amount of the formed chemical conversion film is also shown below. Phosphorus adhesion amount: 1 mg / m ²

Table 1 shows the evaluation results of Examples 1 to 5 and Comparative Examples 1 to 3.

[0043]

[Table 1] Evaluation results

As is clear from the results in Table 1, Examples 1 to 5 using the steel surface-treated can of the present invention are all extremely excellent in both corrosion resistance and adhesion. On the other hand, in Comparative Example 1 with a small amount of carbon and phosphorus attached and Comparative Example 2 with a low coverage, the corrosion resistance and adhesion were poor, and even in Comparative Example 3 using a commercially available tin phosphate-based chemical, the corrosion resistance and
It turns out that paint adhesion is not enough.

[0045]

As is clear from the above description, the steel processing can according to the present invention has an excellent effect of providing a tin-plated steel processing can excellent in corrosion resistance and paint adhesion and a processing method therefor. Play.

[Brief description of the drawings]

FIG. 1 is a drawing (Formula 1) showing a chemical formula of a water-soluble polymer used in the present invention.

FIG. 2 is a drawing (Formula 2) showing a Z group of the water-soluble polymer of FIG. 1.

FIG. 3 is a drawing (Formula 3) showing a chemical formula of a water-soluble polymer used in the present invention.

FIG. 4 is a drawing showing Z of the water-soluble polymer of FIG.
It is.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C23C 22/23 C23C 22/23

Claims (5)

[Claims] 1. A can in which a tin-plated steel sheet is processed and a tin-plated surface is subjected to a surface treatment, comprising a carbon-based organic compound and an inorganic phosphorus compound, and having a thickness of 5%.
An organic-inorganic composite coating in which a coating having a thickness of about 1000 nm is coated at a surface coverage of 90% or more, and the amount of the organic compound deposited is 5 to 300 mg / m ² as carbon;
A tin-plated steel surface-treated can characterized in that the amount of the inorganic phosphorus compound attached is 1 to 60 mg / m ² as phosphorus. 2. The tin-plated steel surface treatment can according to claim 1, wherein the organic compound is a polymer represented by the following general formula. Wherein, in the formula (I), X ¹ and X ²
Each independently represents a hydrogen atom, a C ₁ -C ₅ alkyl group or a C ₁ -C ₅ hydroxyalkyl group,
Y ¹ and Y ² are each independently a hydrogen atom or a Z group represented by the following formula (II): (wherein, in the formula (II), R ¹ and R ² are each other Independently represents a hydrogen atom, a C ₁ -C ₁₀ alkyl group or a member selected from a C ₁ -C ₁₀ hydroxyalkyl group), and each of the Z groups bonded to the benzene ring of the polymer molecule. May be different from each other,
Alternatively, it may be the same as the others, and the average value of the Z group substitution number of each benzene ring in the polymer molecule is 1.0 or less. ] 3. The tin-plated steel surface treatment can according to claim 1, wherein the inorganic phosphorus compound is at least one selected from a phosphoric acid compound, a condensed phosphoric acid compound, a zirconium phosphate compound and titanium phosphate. 4. The tin-plated steel surface-treated can according to claim 1, wherein the processing is drawing and ironing. 5. A phosphate ion of 0.5 to 30 g / L,
0.1 to 20 g / L of condensed phosphate ion or 0.0
5 to 10 g / L complex fluoride ion and 0.1 to 40 g
/ L of the water-soluble polymer of the general formula (I) [provided that the average number of substitutions of the Z group of each benzene ring in the polymer molecule is 0.1.
2 to 1.0, and n represents an average degree of polymerization of 2 to 50. And a surface treatment solution having a pH of 2.2 to 4.5 is heated to 35 to 65 ° C., spray-treated on a tin-plated steel can for 5 to 60 seconds, and then washed with water. A surface treatment method for a tin-plated steel can, characterized by obtaining a steel surface-treated can according to claim 1 by performing a heat-drying treatment.