JPH05163584A - Surface treating liquid for di can of tin plate - Google Patents

Abstract

PURPOSE:To provide a novel surface treating liq. which imparts excellent corrosion resistance and adhesion of a coating material to the surface of a DI can of tin plate by treating the can at a low temp. before coating and printing and produces a very small amt. of sludge in the case waste water is treated. CONSTITUTION:This surface treating liq. for a DI can of tin plate is an aq. soln. of pH 1.5-3.5 contg. 10-500ppm phosphoric acid radicals, 10-500ppm (expressed in terms of fluorine) fluoride and 5-500ppm tin.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a tin DI plate formed by drawing and ironing a tin-plated steel sheet and then coating and printing the tinplate DI can with excellent corrosion resistance and paint on the surface of the tin can. The present invention relates to a novel surface treatment liquid for tin tin DI cans, which provides adhesion by low-temperature treatment and has very little sludge generated by wastewater treatment.

[0002]

2. Description of the Related Art Regarding the surface treatment liquid for tinplate DI cans, for example, Japanese Patent Application Laid-Open No. 1-10028 related to the same applicant as the present application.
The invention of Japanese Patent No. 1 is cited. This invention has a phosphate ion of 1 to 50 g / l and an oxygenate ion of 0.2 to 20.0 g / l.
1, a tin ion of 0.01 to 5.0 g / l, a condensed phosphate ion of 0.01 to 5.0 g / l, and a metal surface treatment film forming solution having a pH of 2 to 6, which is a chemical forming solution. The phosphoric acid-treated film having excellent corrosion resistance can be formed on the surface of the tin plate DI can by treating the surface of the tinplate DI can.

[0003]

On the other hand, the surface treatment equipment for DI cans is usually called a washer, and the molded DI cans are continuously treated with a degreasing liquid or a chemical conversion liquid in an inverted state. The existing washer has six steps of preliminary degreasing, degreasing, water washing, chemical conversion treatment, water washing, and deionized water washing. The treatment liquid discarded from this washer is discharged through a wastewater treatment process. In recent years, the regulated value of discharged water has become stricter due to environmental problems, and reduction of wastewater treatment load is a major problem.

When the above-mentioned invention is actually used, solid waste (hereinafter referred to as sludge) is generated by the wastewater treatment, although it is not necessary to perform particularly advanced wastewater treatment. Current,
Although this sludge is disposed of as industrial waste, reduction of this sludge is desired from the viewpoint of cost reduction and environmental protection. The processing temperature of the above-mentioned invention is usually 6
A chemical conversion agent that is as high as 0 ° C. and can be processed at low temperature is desired. That is, there is a demand for a treatment liquid which imparts excellent corrosion resistance and paint adhesion to the tinplate DI can surface by low-temperature treatment, has a low wastewater treatment load, and produces a small amount of sludge.

[0005]

As a result of studying these problems, the present inventor found that before painting / printing tinplate DI cans,
We have found a new surface treatment liquid for tinplate cans, which gives excellent corrosion resistance and paint adhesion to the surface of the cans by low-temperature treatment, and produces very little sludge generated by wastewater treatment.
That is, the present invention, phosphate group 10 ~ 500ppm,
Disclosed is a surface treatment liquid for tinplate DI cans, which is an aqueous solution containing 10 to 500 ppm of fluoride as fluorine and 5 to 500 ppm of tin and having a pH of 1.5 to 3.5.

The structure of the present invention will be described in detail below. The surface treatment liquid of the present invention relates to an acidic aqueous solution containing phosphate, fluoride and tin as essential components. Phosphoric acid (H ₃ PO ₄ ), sodium phosphate (Na ₃ PO ₄ ), and the like can be used to contain the phosphate group. The content is preferably in the range of 10 to 500 ppm, especially 20 to 90 p
A range of pm is preferred. If it is less than 10 ppm, reactivity is poor and a film is not sufficiently formed. A good film is formed even if it exceeds 500 ppm, but this is a problem because the amount of sludge generated by the wastewater treatment increases.

[0007] To contain fluoride hydrofluoric acid (HF) or a salt such as sodium fluoride (NaF) and a fluoropolymer zirconate (H ₂ ZrF ₆₎ and Furoorochitan acid (H ₂ TiF ₆₎ and its salts Etc. can be used. The content of fluorine is preferably in the range of 10 to 500 ppm, particularly preferably 20 to 90 ppm. 20
If it is less than ppm, reactivity is poor and a film is not formed. 5
Even if it exceeds 00 ppm, a good film is formed, but the etching amount increases and the appearance becomes poor, which is a problem.

The method for mixing tin is not particularly limited. Stannous chloride (SnCl ₂ ), stannic chloride (SnCl ₄ ), stannous fluoride (SnF ₂ ), stannic fluoride (SnF ₄ ), etc. may be used, or metallic tin or tin The DI can may be dissolved and mixed. The tin content is preferably in the range of 5 to 500 ppm. Particularly, the range of 10 to 100 ppm is preferable. If it is less than 5 ppm, a film having excellent corrosion resistance cannot be formed sufficiently. 500p
Even if it exceeds pm, a good film is formed, but tin is likely to precipitate as a hydroxide, and the stability of the liquid is lowered, which is not preferable. In addition, when the stability of the treatment liquid decreases due to iron or tin metal ions eluted from the tin plate, an organic acid such as gluconic acid or oxalic acid may be added.

The pH of the treatment liquid is adjusted to 1.5 to 3.5, but if it is less than 1.5, it becomes difficult to form a film due to excessive etching, and if it exceeds 3.5, a film excellent in corrosion resistance. Are less likely to be formed. Therefore, the pH is 1.
It must be controlled in the range 5 to 3.5. A more preferable pH range is 2.3 to 3.0. pH is
It is adjusted by using an acid such as phosphoric acid, nitric acid or hydrofluoric acid and an alkali such as sodium hydroxide, sodium carbonate or ammonium hydroxide.

Next, a method for producing the surface treatment liquid of the present invention will be outlined. According to the method described above, a predetermined amount of phosphate, fluoride and tin are dissolved in water and sufficiently stirred. Then with stirring. Adjust pH as described above.

Next, the film to be formed will be outlined. The film formed by the surface treatment liquid of the present invention is a tin hydroxide and an inorganic film containing tin oxide as a main component. Next, the treatment process of tinplate DI cans to which the surface treatment liquid of the present invention is applied will be outlined. The treatment liquid of the present invention is preferably used in the following process.

Surface cleaning of tinplate D can: Degreasing (generally a weak alkaline detergent is used) Water washing Film formation treatment (application of the treatment liquid of the present invention) Treatment temperature: normal temperature to 50 ° C Treatment method: Spray Treatment time: 2-60 seconds Washing with water Deionized washing with water Drying

The treatment temperature of the surface treatment liquid of the present invention is from room temperature to 5
The temperature can be up to 0 ° C, but it is usually preferable to heat it to 30 to 35 ° C before use. The temperature is significantly lower than the conventional processing temperature (60 ° C.). The spraying time is 2 to 60 seconds, but if it is less than 2 seconds, it does not react sufficiently and a film having excellent corrosion resistance cannot be formed. Even if the time is longer than 60 seconds, the performance is not improved. Therefore, the processing time should be in the range of 2-60 seconds.

[0014]

EXAMPLES Some examples of the surface treatment liquid of the present invention will be given below, and their usefulness will be shown in comparison with comparative examples. The corrosion resistance of the can was evaluated by the iron exposure degree (IEV). In addition,
The measurement of IEV is based on the U.S.P. S. Patent 4332646
According to. The lower the IEV value, the better the corrosion resistance, usually 1
It is good if it is 50 or less. For paint adhesion, an epoxyurea-based paint for cans is applied to the surface of the treated can to a coating thickness of 5 to 7 μm, and baked at 215 ° C. for 4 minutes.
A strip of m was cut and thermocompression-bonded with a polyamide-based film to obtain a test piece, which was peeled by the 180-degree peel test method, and the peel strength was evaluated. Therefore, the greater the peel strength, the better the paint adhesion. Generally 1.
It is good if the width is 5 kgf / 5 mm or more. The wastewater treatability was evaluated by the following method. The treatment liquid is diluted to 1/10 (in the actual operation, the treatment liquid is diluted to this extent and the wastewater is treated), and calcium hydroxide (Ca (OH)
₂ ) was added until about pHIO. Next, an aluminum sulfate aqueous solution was added as aluminum to 20 ppm, and the pH was adjusted to 10 with calcium hydroxide. This liquid was allowed to stand for 1 hour, and then solid-liquid separation was performed.
The phosphorus, fluorine, and tin concentrations in the liquid were measured, and it was confirmed that these components had precipitated. Then, the remaining sludge (solid content) was dried at 110 ° C. for 24 hours, cooled and then weighed. The wastewater treatability was evaluated from this weight. That is, it is preferable that the generated weight of sludge is small.

Example 1 A tin-plated DI can made by tin-processing a tin-plated steel sheet with a weak alkaline degreasing agent (registered trademark Fine Cleaner 436).
1A, manufactured by Nihon Parkerizing Co., Ltd.), the surface treatment liquid 1 was heated to 30 ° C., sprayed for 30 seconds, and then washed with tap water.
10 more with deionized water of more than 3,000,000 Ωcm
After spraying for 2 seconds, it was dried in a hot air drying oven at 180 ° C. for 3 minutes. Then, the corrosion resistance and adhesion of this treated can were evaluated. Further, the wastewater treatment property of this surface treatment liquid 1 was evaluated.

Surface treatment liquid 1 75% phosphoric acid (H ₃ PO ₄ ) 69 ppm (PO ₄ : 50 ppm) 20% hydrofluoric acid (HF) 210 ppm (F: 40 ppm) Stannous chloride (SnCl ₄ .5H ₂ O) ) 30ppm (Sn: 10ppm) pH 2.5 (adjusted with ammonia water)

Example 2 After cleaning the tinned DI can under the same conditions as in Example 1, the surface treatment liquid 2 was heated to 30 ° C. and sprayed for 30 seconds. After the treatment, it was washed with water and dried under the same conditions as in Example 1. Then, the corrosion resistance and adhesion of this treated can were evaluated. In addition, the wastewater treatment property of this surface treatment liquid 2 was evaluated.

The surface treatment bath 2 75% phosphoric acid _{(H 3 PO 4) 110ppm (} PO 4: 80ppm) 20% fluozirconic acid _{(H 2 ZrF 6) 500ppm (} F: 40ppm) stannic chloride (SnCl ₄ · 5H ₂ O) 30ppm (Sn: 10ppm) pH 3.0 (adjusted with ammonia water)

Example 3 The tinned DI can was cleaned under the same conditions as in Example 1, and then the surface treatment liquid 3 was heated to 30 ° C. and sprayed for 3 seconds. After the treatment, it was washed with water and dried under the same conditions as in Example 1. Then, the corrosion resistance and adhesion of this treated can were evaluated. Further, the wastewater treatment property of this surface treatment liquid 3 was evaluated.

Surface treatment liquid 3 75% phosphoric acid (H ₃ PO ₄ ) 69 ppm (PO ₄ : 50 ppm) 20% hydrofluoric acid (HF) 420 ppm (F: 80 ppm) Metal tin (Sn) 60 ppm (Sn: 20 ppm) pH 2.7 (adjusted with sodium hydroxide)

Example 4 Under the same conditions as in Example 1, the tinned DI can was cleaned, and then the surface treatment liquid 4 was heated to 30 ° C. and sprayed for 3 seconds. After the treatment, it was washed with water and dried under the same conditions as in Example 1. Then, the corrosion resistance and adhesion of this treated can were evaluated. Further, the wastewater treatment property of this surface treatment liquid 4 was evaluated.

Surface treatment liquid 4 75% phosphoric acid (H ₃ PO ₄ ) 110 ppm (PO ₄ : 80 ppm) 20% fluorozirconic acid (H ₂ ZrF ₆ ) 500 ppm (F: 55 ppm) Stannous chloride (SnCl ₂ .2H) ₂ O) 19ppm (Sn: 10ppm) pH 2.5 (adjusted with sodium hydroxide)

Example 5 The tinned DI can was cleaned under the same conditions as in Example 1, and then the surface treatment liquid 5 was heated to 60 ° C. and sprayed for 30 seconds. After the treatment, it was washed with water and dried under the same conditions as in Example 1. Then, the corrosion resistance and adhesion of this treated can were evaluated. Further, the wastewater treatment property of this surface treatment liquid 5 was evaluated.

Surface Treatment Solution 5 Sodium Phosphate (Na ₃ PO ₄ ) 86ppm (PO ₄ : 50ppm) 20% Hydrofluoric Acid (HF) 210ppm (F: 40ppm) Stannous Chloride (SnCl ₂ · 2H ₂ O) 19ppm (Sn: 10ppm) pH 2.5 (adjusted with nitric acid)

Example 6 After cleaning the tinned DI can under the same conditions as in Example 1, the surface treatment liquid 6 was heated to 30 ° C. and sprayed for 30 seconds. After the treatment, it was washed with water and dried under the same conditions as in Example 1. Then, the corrosion resistance and adhesion of this treated can were evaluated. Further, the wastewater treatment property of this surface treatment liquid 6 was evaluated.

Surface treatment liquid 6 75% phosphoric acid (H ₃ PO ₄ ) 207 ppm (PO ₄ : 150 ppm) 20% hydrofluoric acid (HF) 105 ppm (F: 20 ppm) Stannous chloride (SnCl ₄ · 5H ₂ O) ) 30ppm (Sn: 10ppm) pH 2.5 (adjusted with ammonia water)

Example 7 The tinned DI can was cleaned under the same conditions as in Example 1, and then the surface treatment liquid 7 was heated to 30 ° C. and sprayed for 30 seconds. After the treatment, it was washed with water and dried under the same conditions as in Example 1. Then, the corrosion resistance and adhesion of this treated can were evaluated. In addition, the wastewater treatment property of this surface treatment liquid 7 was evaluated.

Surface treatment liquid 7 75% phosphoric acid (H ₃ PO ₄ ) 110 ppm (PO ₄ : 80 ppm) 20% fluorozirconic acid (H ₂ ZrF ₆ ) 500 ppm (F: 55 ppm 20% hydrofluoric acid (HF) 210 ppm (F: 4 ppm) F: 95 ppm in total Stannous chloride (SnCl ₄ .5H ₂ O) 30 ppm (Sn: 10 ppm) pH 2.5 (adjusted with ammonia water)

Example 8 Under the same conditions as in Example 1, the tinned DI can was cleaned, and then the surface treatment liquid 1 was heated to 50 ° C. and sprayed for 30 seconds. After the treatment, it was washed with water and dried under the same conditions as in Example 1. Then, the corrosion resistance and adhesion of this treated can were evaluated.

Example 9 After cleaning the tinned DI can under the same conditions as in Example 1, the surface treatment liquid 1 was heated to 30 ° C. and sprayed for 10 seconds. After the treatment, it was washed with water and dried under the same conditions as in Example 1. Then, the corrosion resistance and adhesion of this treated can were evaluated.

The results are shown in Table 1. It can be seen that the surface treatment liquid of the present invention forms a film having excellent corrosion resistance and adhesion by low-temperature treatment, and generates less sludge.

[0032]

[Table 1]

Comparative Example 1 After cleaning the tinned DI can under the same conditions as in Example 1, the surface treatment liquid 8 was heated to 30 ° C. and sprayed for 30 seconds. After the treatment, it was washed with water and dried under the same conditions as in Example 1. Then, the corrosion resistance and adhesion of this treated can were evaluated. Further, the wastewater treatment property of this surface treatment liquid 8 was evaluated.

Surface Treatment Liquid 8 Sodium Phosphate (Na ₃ PO ₄ ) 86 ppm (PO ₄ : 50 ppm) 20% Hydrofluoric Acid (HF) 210 ppm (F: 40 ppm) Stannous Chloride (SnCl ₂ · 2H ₂ O) 19ppm (Sn: 10ppm) pH 4.0 (adjusted with sodium hydroxide)

Comparative Example 2 After cleaning the tinned DI can under the same conditions as in Example 1, the surface treatment liquid 9 was heated to 50 ° C. and sprayed for 30 seconds. After the treatment, it was washed with water and dried under the same conditions as in Example 1. Then, the corrosion resistance and adhesion of this treated can were evaluated. Further, the wastewater treatment property of this surface treatment liquid 9 was evaluated.

Surface Treatment Liquid 9 Sodium Phosphate (Na ₃ PO ₄ ) 86ppm (PO ₄ : 50ppm) 20% Hydrofluoric Acid (HF) 210ppm (F: 40ppm) pH 3.0 (adjusted with nitric acid)

Comparative Example 3 After cleaning the tinned DI can under the same conditions as in Example 1, the surface treatment liquid 10 was heated to 30 ° C. and sprayed for 30 seconds. After the treatment, it was washed with water and dried under the same conditions as in Example 1. afterwards,
The corrosion resistance and adhesion of this treated can were evaluated. Further, the wastewater treatment property of this surface treatment liquid 10 was evaluated.

Surface treatment liquid 10 75% phosphoric acid (H ₃ PO ₄ ) 69 ppm (PO ₄ : 50 ppm) 20% hydrofluoric acid (HF) 210 ppm (F: 40 ppm) Stannous chloride (SnCl ₂ .2H ₂ O) ) 19ppm (Sn: 10ppm) pH 1.4 (adjusted with nitric acid)

Comparative Example 4 After cleaning the tinned DI can under the same conditions as in Example 1, the surface treatment liquid 11 was heated to 30 ° C. and sprayed for 30 seconds. After the treatment, it was washed with water and dried under the same conditions as in Example 1. afterwards,
The corrosion resistance and adhesion of this treated can were evaluated. Further, the wastewater treatment property of this surface treatment liquid 11 was evaluated.

Surface treatment liquid 11 75% phosphoric acid (H ₃ PO ₄ ) 12000 ppm (PO ₄ : 8724 ppm) 20% hydrofluoric acid (HF) 210 ppm (F: 40 ppm) Stannous chloride (SnCl ₂ .2H ₂ O) ) 76 ppm (Sn: 40 ppm) pH 3.0 (adjusted with sodium hydroxide)

Comparative Example 5 After cleaning the tinned DI can under the same conditions as in Example 1, the surface treatment liquid 12 was heated to 30 ° C. and sprayed for 30 seconds. After the treatment, it was washed with water and dried under the same conditions as in Example 1. afterwards,
The corrosion resistance and adhesion of this treated can were evaluated. Further, the wastewater treatment property of this surface treatment liquid 12 was evaluated.

Surface treatment liquid 12 75% phosphoric acid (H ₃ PO ₄ ) 10000 ppm (PO ₄ : 7270 ppm) Sodium tripolyphosphate (Na ₅ P ₃ O ₁₀ ) 400 ppm (P ₃ O ₁₀ 275 ppm) Stannous chloride (SnCl) _{2 · 2H 2 O) 76ppm (} Sn: 40ppm) pH 3.0 ( adjusted with sodium hydroxide)

[0043]

As described above, by coating a tin can with the surface treatment liquid of the present invention, coating
It has the excellent effects of imparting excellent corrosion resistance and paint adhesion to the surface of tinplate DI cans before printing by low-temperature treatment, and generating very little sludge during wastewater treatment.

Claims (1)

[Claims] 1. A phosphate group of 10 to 500 ppm, a fluoride of 10 to 500 ppm as fluorine, and a tin of 5 to 5 ppm.
A surface treatment liquid for tinplate DI cans, which is an aqueous solution containing 00 ppm and having a pH of 1.5 to 3.5.