JPH0784665B2 - Aluminum conversion treatment method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for rapidly converting aluminum or its alloys.

Conventional technology Aluminum or its alloy (hereinafter simply referred to as aluminum)
Is used as a sheet or a beverage can.

In the case of a can, it is manufactured by a drawing method called drawing and ironing, and the lubricant and molding oil used at that time adhere to the surface of the can, and aluminum powder remains and adheres to the inner wall of the container. . The following techniques have been proposed as such degreasing, cleaning, and chemical conversion treatment methods for aluminum.

In Japanese Examined Patent Publication No. 53-28245, as a method for degreasing and cleaning aluminum, a cleaning aqueous solution containing about 1 to 10 g / liter of sulfuric acid with a pH of about 1.0 to 1.8 and about 0.005 to 0.01 g / liter of hydrofluoric acid is used. The surface can be contacted at 43 to 57 ° C; in JP-A-59-133382, in order to apply a chemical conversion coating to an aluminum container, as a method for purifying and etching oil, debris and other deposits from the surface of the container, To spray a dilute alkaline aqueous solution of about 6 to 12 g / liter of alkali metal hydroxide and about 3 to 6 g / liter of chelating agent at about 26 to 54 ° C to form a clean bright surface; In Kaisho 58-1078, about 0.5 to 3 g / liter of an alkali metal hydroxide and about 1 to 5 g / liter of ethylenediamine tetra are used as a cleaning aqueous solution for removing and dissolving aluminum debris from the aluminum surface and cleaning the lubricating oil. Acetic acid alkali A combination containing a metal salt, a surfactant of about 0.1 to 10 g / liter, and an alkali metal salt of gluconate as an aluminum sequestering agent; Japanese Patent Publication No. 56-33468 discloses black resistance to boiling water on aluminum. Disclosed is a composition containing PH 1.5 to 4.0, zirconium, titanium or a mixture thereof of 10 PPM or more, a phosphate of 10 PPM or more and an effective fluoride effective for forming a coating capable of providing a coated surface having There is.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention is to accelerate degreasing, cleaning, chemical conversion treatment and the like in order to improve productivity while maintaining quality level.

Means for Solving the Problems Constitution of the Invention The first chemical conversion treatment method of the present invention comprises: (a) aluminum or its alloy with 1 to 10 g / liter of PO ₄ ions and 0.1
~ 3g / liter aluminum chelating agent, 0.1 ~ 5g
Degreasing is carried out by spraying a degreasing agent containing a surfactant / liter of which the pH is adjusted to 11 to 13 with an alkali metal hydroxide for 4 to 8 seconds, and then (b) 0.01 to 0.5 g / liter. Zr ions of 0.01-0.5g /
It is characterized in that a chemical conversion treatment agent containing liters of PO ₄ ions and 0.001 to 0.05 g / liter of effective F ions and having a pH adjusted to 1.5 to 4.0 is sprayed for 3 to 7 seconds.

Further, the second chemical conversion treatment method of the present invention comprises (a) aluminum or an alloy thereof, 1 to 10 g / liter of PO ₄ ion, and 0.1 to 3 g / liter of an aluminum chelating agent,
Degreasing is performed with a degreasing agent containing 0.1 to 5 g / liter of a surfactant and having a pH adjusted to 11 to 13 with an alkali metal hydroxide, and then (b) 0.01 to 1 g / liter of V ions and 0.01 ~ 0.5g / l Zr ion, 0.01-0.5g / l PO ₄ ion, 0.001-0.05g / l effective F ion are contained, and the chemical conversion treatment agent whose pH is adjusted to 1.5-4.0 is applied. It is characterized by doing.

The degreasing agent used in the present invention is an alkali metal hydroxide having a pH of 11
A degreasing agent containing 1 to 10 g / liter aluminum chelating agent 0.1 to 3 g / liter as a PO4 ion adjusted to 13 to 0.1 to 5 g / liter surfactant is suitable, and alkali metal hydroxide for adjusting PH is used. As the substance, sodium hydroxide, potassium hydroxide, lithium hydroxide or the like is used.

If the pH is less than 11, the degreasing and desmutting properties are insufficient, and the coating film adhesion decreases.

Also, if PH exceeds 13, the etching amount will be too large,
Since the poor appearance (whitening) and boiling water resistance to blackening also decrease,
Not preferable.

Phosphoric acid and its salts as a source of PO4 ions in the degreasing agent, especially Na ₃ PO4 orthophosphate are preferred for example, Na ₂ HPO _4, with _{(NH4) 3 PO 4, K} 3 PO 4, K 2 HPO 4 , etc. If the blending amount is less than 1 g / liter in terms of PO ₄ , the appearance will be whitened, and the blackening resistance to boiling water will be reduced.

On the other hand, if it exceeds 10 g / liter, the adhesion to the coating film is deteriorated and the stability of the bath is also deteriorated, which is not preferable.

What is used as an aluminum chelating agent is gluconic acid, heptonic acid, ethylenediaminetetraacetic acid and its salts, etc., and the compounding amount of which is less than 0.1 g / liter has a low ability to hold aluminum in a dissolved state, The stability is also insufficient. Further, the desmutting property and the adhesion to the coating film are deteriorated.

Further, even if it exceeds 3 g / liter, no further effect is observed, and the economical efficiency is lowered.

What is used as a surfactant may be any of nonionic, anionic, and cationic, but nonionic is preferable in consideration of foamability and the like, and if the compounding amount is less than 0.1 g / liter, degreasing and desmutting properties are obtained. In addition, since the amount of oil remaining on the treated product increases, a uniform film is not formed in the subsequent chemical conversion treatment, the blackening resistance to boiling water resistance and the adhesion to the coating film also decrease.

Further, even if it exceeds 5 g / l, no further effect is observed, and considering the economy, the foamability of the bath, and the wastewater treatment property.
5 g / l is sufficient.

Next, the chemical conversion treatment agent (A) preferably has a pH of 1.5 to 4.0. When the pH is less than 1.5, the etching reaction of aluminum becomes too large and the film is hard to form. al-PO precipitation of ₄ tends to occur, also, satisfactory coating slows film formation rate is not generated.

The pH is preferably adjusted using an inorganic acid such as nitric acid or sulfuric acid, a metal hydroxide such as sodium hydroxide or potassium hydroxide, or ammonia water. Although it is not impossible to use phosphoric acid, since the amount of PO4 ions in the chemical conversion treatment agent (A) is regulated within a specific range (0.01 to 0.5 g / liter), the pH of the Phosphoric acid cannot be used for conditioning.

The sources of Zr ions include H ₂ ZrF ₆ , (NH ₄ ) ₂ ZrF ₆ and Na.
₂ ZrF ₆ , K ₂ ZrF ₆ , Zr (NO ₃ ) ₄ , ZrO (NO ₃ ) ₂ , Zr (S
O ₄ ) ₂ , ZrOSO _4, etc., and if the blending amount is less than 0.01 g / liter, a satisfactory film is not formed. Also, 0.5g /
Beyond liters, there is no further effect and economic efficiency declines.

As a source of PO ₄ ions in the chemical conversion treatment agent (A), H
₃ PO ₄ , NaH ₂ PO ₄ , (NH ₄ ) H ₂ PO _4, etc., and their compounding amounts are
If it is less than 0.01 g / liter, the adhesiveness with the coating film decreases,
On the other hand, if it exceeds 0.5 g / liter, the blackening resistance to boiling water and the adhesion to the coating film are deteriorated, and a precipitate of Zr or Al—PO ₄ may be formed, which is not preferable.

Sources of effective F ions are HF, NA ₄ F, NH ₄ HF ₂ , Na
F, NaHF _{2 and the} like, and when the blending amount is less than 0.001 g / liter, the etching reaction of aluminum hardly occurs and a film is not formed.

On the other hand, if it exceeds 0.05 g / liter, the etching reaction of aluminum becomes larger than the rate of film formation, and it becomes difficult to form a film.

Further, even if a film is formed, the resistance to blackening by boiling water and the adhesion to the coating film are reduced.

A fluorine compound that does not release fluorine ions in the chemical conversion treatment agent is not suitable as a source of effective fluorine ions.

Next, the chemical conversion treatment agent (B) preferably has a PH of 1.5 to 4.0, and when the PH is less than 1.5, the etching reaction of aluminum becomes too large, which makes it difficult to form a film.
Further, if it exceeds 4.0 Zr, it becomes V, the precipitation of the Al-PO ₄ prone, also slows film generation speed, satisfactory coating is not generated.

The pH is preferably adjusted using an inorganic acid such as nitric acid or sulfuric acid, a metal hydroxide such as sodium hydroxide or potassium hydroxide, or ammonia water. It should be noted that it is not impossible to use phosphoric acid, but the amount of PO4 ions in the chemical conversion treatment agent (B) is regulated within a specific range (0.01 to 0.5 g / liter), so PH adjustment is possible only within the previous period. It is not possible to use phosphoric acid.

Sources of V ions include hanazic acid such as VHO ₃ , NH ₄ VO ₃ and NaVO ₃ and salts thereof, vanadyl salts such as vanadyl sulfate and vanadyl oxalate, and halides such as VF ₅ and their combination. If the amount is less than 0.01 g / liter, blackening resistance to boiling water resistance and coating film adhesion are insufficient.

Moreover, even if it exceeds 1 g / liter, no further effect can be expected.

The sources of Zr ions include H ₂ ZrF ₆ , (NH ₄ ) ₂ ZrF ₆ and Na.
₂ ZrE ₆ , K ₂ ZrE ₆ , Zr (NO ₃ ) ₄ , ZrO (NO ₃ ) ₂ , Zr (S
O ₄ ) ₂ , ZrOSO _4, etc., and if the blending amount is less than 0.01 g / liter, a satisfactory film is not formed.

If it exceeds 0.5 g / liter, no further effect can be expected.

Sources of PO ₄ ions in the chemical conversion treatment agent (B) include H ₃ PO ₄ , NaH ₂ PO ₄ , (NH ₄ ) H ₂ PO _4, etc., and their blending amount is less than 0.01 g / liter. Adhesion to the coating film decreases, and if it exceeds 0.5 g / l, boiling water resistance to blackening, adhesion to the coating film decreases, and Zr, V, Al-PO ₄ precipitates easily form. . Sources of effective F ions are HF, NH ₄ F, NH ₄ HF ₂ , NaF, NaHF _2, etc., and their blending amount is 0.00
If the amount is less than 1 g / liter, the aluminum etching reaction hardly occurs and the film is not formed.

On the other hand, if it exceeds 0.05 g / liter, the etching reaction of aluminum becomes larger than the rate of film formation, and it becomes difficult to form a film.

Further, even if a film is formed, resistance to blackening by boiling water and adhesion to the coating film are reduced.

A fluorine compound that does not release fluorine ions in the chemical conversion treatment agent is not suitable as a source of effective fluorine ions.

The reason why the method of the present invention enables short-time treatment is that by adding phosphoric acid and its salt to a degreasing agent to balance degreasing ability and etching, boiling water resistance after chemical conversion treatment, adhesion to coating film Can obtain a good surface. It is also presumed that the chemical conversion treatment is performed by applying a high concentration chemical conversion treatment agent in a region where the pH is relatively low.

Examples of aluminum or an alloy thereof to which the method of the present invention can be applied include aluminum, aluminum-copper alloy, aluminum-manganese alloy, aluminum-silicon alloy, aluminum-magnesium alloy, aluminum-magnesium-silicon alloy, and aluminum-zinc alloy. , Aluminum-zinc-magnesium alloy, etc., and can be processed in any shape such as plate, rod, wire, tube and the like. In particular, it is suitable for aluminum beverage cans.

In the case of the degreasing agent, the processing conditions of the degreasing agent and the chemical conversion treatment agent are
It is carried out by continuing spraying at 50 to 80 ° C. for 4 to 8 seconds, and then washing with water.

In the case of a chemical conversion treatment agent, spraying is continued at 30 to 60 ° C. for 3 to 7 seconds, followed by washing with water, washing with pure water, drying and application.

Examples 1 to 16 and Comparative Examples 1 to 14 Can bodies obtained by subjecting an aluminum plate (JIS A3004) to drawing and ironing are shown in Tables 1-1, 1-2, 1-3, and 1-4. The composition was degreased by spraying with a degreasing agent and conditions, washed with water, and then spray-treated with surface treatment baths and conditions shown in Tables 2-1, 2-2, 2-3, and 2-4. Next, washing with water and washing with deionized water were carried out, and drying was performed in an oven at 200 ° C (Examples 1 to 16). The dried cans were evaluated for appearance, desmutting property, degreasing property, blackening resistance against boiling water and paint adhesion. The results are shown in Table 3-
1, 3-2, and 3-3.

Similarly, a can body obtained by subjecting an aluminum plate (JIS A3004) to drawing-ironing is spray-degreased with a degreasing agent having the composition shown in Tables 4-1, 4-2, and 4-3, and conditions. After washing with water, spray treatment was carried out under the surface treatment baths and the conditions shown in Tables 5-1, 5-2, and 5-3. Then, washing with water and washing with deionized water were carried out, and drying was performed in an oven at 200 ° C (Comparative Examples 1 to 14). The dried cans were evaluated for appearance, desmutting, degreasing, boiling water black resistance and paint adhesion. The results are shown in Tables 6-1, 6-2,
And 6-3.

[Evaluation method] Appearance Visually judge the gloss and (whiteness) of the container after drying ◎ Slightly glossy ○ Excessive gloss; No too much gloss x No gloss Desmutting property Attach tape to the inner surface of the container after drying, peeling, and contamination Five-level evaluation according to the degree ◎ No pollution ○ Trace-level pollution △ Minor pollution × Moderate pollution × × Great pollution Degreasing Degreasing Measure the residual oil content (μg / can) on the inner surface of the container after drying, Five-level evaluation according to the residual amount ◎ Less than 10 ○ 10 or more and less than 20 △ 20 or more but less than 30 × 30 or more but less than 40 × × 40 or more Resistance to boiling water black modification Resistance to black boiling water modification Black water 30 minutes after boiling water (can Bottom) ◎ No blackening at all ○ Slightly blackening △ Slightly blackening × Quite blackening × × Completely blackening Coating adhesion Adhesion of epoxy phenolic paint to the inner surface of the container, baking and drying (215 ° C × 3 Minutes) and use it as a sample. Five-stage evaluation based on the number of remaining frames ◎ 100; ○ 90 to 99 △ 80 to 89; × 70 to 79 × less than 70 The effect of the present invention The present invention prevents formation of excessive etching to form a film in an extremely short time. The boiling water resistance after treatment and the adhesion to the coating film were able to obtain higher quality than before and the productivity could be greatly improved.

Claims (2)

[Claims] 1. To (a) aluminum or an alloy thereof, 1
And PO ₄ ions to 10 g / l, contains an aluminum chelating agent 0.1 to 3 g / l, and a surfactant 0.1-5 g / l, and the pH was adjusted to 11-13 with an alkali metal hydroxide Degreasing is performed by spraying a degreasing agent for 4 to 8 seconds, and then (b) 0.01 to 0.5 g / liter Zr ions and 0.01 to 0.5 g / liter.
A chemical conversion treatment method comprising spraying a chemical conversion treatment agent containing liters of PO ₄ ions and 0.001 to 0.05 g / liter of effective F ions and having a pH adjusted to 1.5 to 4.0 for 3 to 7 seconds. 2. To (a) aluminum or an alloy thereof, 1
And PO ₄ ions to 10 g / l, contains an aluminum chelating agent 0.1 to 3 g / l, and a surfactant 0.1-5 g / l, and the pH was adjusted to 11-13 with an alkali metal hydroxide Degreasing is performed with a degreasing agent, and then (b) 0.01 to 1 g / liter V ion, 0.01 to 0.5 g / liter Zr ion, 0.01 to 0.5 g / liter PO ₄ ion, and 0.001 to 0.05 g / liter. And a chemical conversion treatment agent having a pH adjusted to 1.5 to 4.0.