JP5122869B2 - Metal surface treatment composition and aluminum-based metal surface treatment plate - Google Patents

Description

  The present invention relates to a metal surface treatment composition and an aluminum metal surface treatment plate used for pre-coating of aluminum metals such as aluminum and aluminum alloys used for cans and the like.

  Conventionally, chromate chemical conversion treatment agents are known as chemical conversion treatment agents used for surface treatment of aluminum-based metals. The chromate conversion coating formed by the chromate conversion treatment agent has excellent corrosion resistance and adhesion after application of various paints, so its application covers a wide range of building materials, home appliances, fin materials, car evaporators, beverage cans, etc. Patent Document 1). However, since the chromate chemical conversion treatment agent uses harmful chromium metal, it is difficult to treat the waste liquid. For this reason, environment-friendly non-chromium metal surface treatment agents are becoming mainstream in recent years.

  As a non-chromium chemical conversion treatment agent, Patent Document 2 discloses a surface treatment agent for aluminum containing zirconium and / or titanium, phosphate and fluoride. However, with this technique, the high adhesion to the paint and the anticorrosion as a coating material are insufficient as a coating base for an aluminum alloy lid material of a metal can.

  Patent Document 3 discloses a metal surface treatment agent containing a water-soluble zirconium compound, a water-soluble or water-dispersible acrylic resin, and a water-soluble or water-dispersible thermosetting crosslinking agent, Zirconium has a mass basis of 500 to 15000 ppm, the acrylic resin has a solid content acid value of 150 to 740 mg KOH / g and a solid content hydroxyl value of 24 to 240, and a solid content of 500 to 30000 ppm on a mass basis, A metal surface treating agent is disclosed in which the thermosetting crosslinking agent has a solid content of 125 to 7500 ppm on a mass basis. However, when a polyvinyl chloride coating was applied, the adhesion with the polyvinyl chloride coating film was insufficient.

Furthermore, Patent Document 4 exemplifies sorbitol as an aluminum ion sealing agent. However, the treatment liquid containing the aluminum ion sealing agent is an aqueous alkaline cleaning liquid before chemical conversion treatment, and is not a chemical conversion treatment liquid, and its purpose is to seal aluminum ions generated by etching. The technical idea is different.
JP-A-5-125555 Japanese Patent Publication No.56-33468 JP 2000-275648 A JP-A-9-111465

  The object of the present invention is that before the application of an aluminum-based metal, which has a performance equal to or higher than that of a conventionally known phosphoric acid chromate, and has excellent adhesion and corrosion resistance to a coating film obtained from a paint for cans such as a vinyl chloride paint. The object is to provide a non-chromium metal surface treatment composition for use in the treatment.

  The inventors of the present invention have made extensive studies to solve the above problems. As a result, it has been found that a metal surface treatment composition containing a predetermined amount of fluorine ions, zirconium ions, aluminum ions, and an aluminum ion scavenger in the metal surface treatment composition can solve the above-mentioned problems, and completes the present invention. It came to. More specifically, the present invention provides the following.

  (1) A metal surface treatment composition used for pre-coating treatment of an aluminum-based metal plate, comprising a fluorine ion, a zirconium ion, an aluminum ion, and an aluminum ion scavenger.

  (2) The metal surface treatment composition according to (1), wherein the aluminum ion scavenger is polyitaconic acid.

  (3) The metal surface treatment composition according to (1), wherein the aluminum ion scavenger is a monosaccharide alcohol.

  (4) The metal surface treatment composition according to (3), wherein the monosaccharide alcohol is sorbitol.

  (5) The metal surface treatment composition according to (1), wherein the aluminum ion scavenger is a disaccharide alcohol.

  (6) The metal surface treatment composition according to (5), wherein the disaccharide alcohol is maltitol.

  (7) The amount of effective fluorine ions is 1 ppm to 1000 ppm, the zirconium ion is 10 ppm to 10000 ppm in terms of metal element, the aluminum ion is 10 ppm to 2000 ppm in terms of metal element, and the aluminum ion scavenger The metal surface treatment composition according to any one of (1) to (6), which is contained in an amount of 50 ppm to 10000 ppm and has a pH of 2 or more and 5 or less.

(8) By bringing the metal surface treatment composition into contact with at least one surface of an aluminum-based metal plate under conditions of a liquid temperature of 30 ° C. or more and 70 ° C. or less and a treatment time of 1 second or more and 60 seconds or less, the aluminum system Zirconium on the surface of the metal plate is 2 mg / m ² or more and 100 mg / m ² or less in terms of metal element, and the aluminum ion scavenger is 0.5 mg / m ² or more and 20 mg / m in terms of organic carbon derived from the aluminum ion scavenger. ^An aluminum-based metal surface-treated plate on which a chemical conversion film containing ² or less is formed.

  According to the present invention, it has high adhesion to aluminum-based metals used for cans and the like, can impart good corrosion resistance to the metal material, and has a performance equal to or higher than that of a conventional phosphate chromate treatment agent. It is possible to provide a non-chromium metal surface treatment composition used for pre-coating treatment of an aluminum metal.

  The metal surface treatment composition of the present invention contains a predetermined amount of fluorine ions, zirconium ions, aluminum ions, and an aluminum ion scavenger. When the surface of an aluminum-based metal is treated using the metal surface treatment composition of the present invention, as well known to those skilled in the art, aluminum is dissolved by fluorine ions, resulting in an increase in pH. A zirconium compound precipitates. At this time, the aluminum compound is precipitated at the same time, and it is considered that a composite chemical conversion film with the zirconium compound is formed. In the present invention, it is considered that the aluminum ion scavenger is deposited at the same time and is present in the vicinity of the surface of the composite chemical coating, considering the improvement in adhesion and the reason for the excellent adhesion.

  On the other hand, it is generally known that when an aluminum-based metal is etched with fluorine ions, aluminum ions are supplied into the treatment bath and cause aluminum sludge. However, in the metal surface treatment composition of the present invention, the formation of aluminum sludge is greatly suppressed. This is considered to be because in the metal surface treatment composition of the present invention, some interaction exists between the aluminum ion scavenger and the aluminum ions, and thereby the aluminum ions are stabilized in the treatment bath. .

  The manufacturing method of the metal surface treatment composition of this invention is not specifically limited, After mix | blending a fluorine ion, a zirconium ion, an aluminum ion, and an aluminum ion scavenger as shown below, it adjusts pH and is obtained.

<Fluorine ion>
The metal surface treatment composition of the present invention preferably contains 1 ppm or more and 1000 ppm or less, more preferably 5 ppm or more and 100 ppm or less, with fluorine ions as the effective fluorine ion content. Here, the “effective fluorine ion amount” means the concentration of fluorine ions in a free state in the treatment bath, and is obtained by measuring the treatment bath with a measuring instrument having a fluorine ion electrode. When the effective content of fluorine ions is less than 1 ppm, etching is insufficient and a sufficient amount of zirconium film cannot be obtained, so that adhesion and corrosion resistance are lowered. When the amount is more than 1000 ppm, the etching is excessive and the zirconium film is not deposited, and the adhesion and corrosion resistance are lowered. Examples of the fluorine ion source include hydrofluoric acid, ammonium fluoride, ammonium hydrofluoride, sodium fluoride, sodium hydrofluoride and the like in addition to the fluorinated zirconate compound. The effective fluorine ion concentration can be adjusted.

<Zirconium ion>
The content of zirconium ions in the metal surface treatment composition of the present invention is preferably 10 ppm or more and 10,000 ppm or less, more preferably 50 ppm or more and 1000 ppm or less. When the content of zirconium ions is less than 10 ppm, the corrosion resistance decreases because the zirconium content in the chemical conversion film is small. When the amount is more than 10,000 ppm, the improvement in performance cannot be expected, which is disadvantageous in terms of cost. Examples of the zirconium ion source include fluorozirconic acid or its lithium, sodium, potassium, ammonium salt, zirconium fluoride, and the like. It can also be obtained by dissolving a zirconium compound such as zirconium oxide in an aqueous fluoride solution such as hydrofluoric acid.

<Aluminum ion>
The content of aluminum ions in the metal surface treatment composition of the present invention is preferably 10 ppm or more and 2000 ppm or less, more preferably 50 ppm or more and 500 ppm or less. If the content of aluminum ions is less than 10 ppm, a chemical conversion film having excellent adhesion cannot be obtained. When the amount is more than 2000 ppm, the amount of the aluminum ion scavenger is relatively insufficient, so that the component balance of the metal surface treatment composition may be lost and a large amount of sludge may be generated.

  Examples of the aluminum ion source include aluminum hydroxide, aluminum fluoride, aluminum oxide, aluminum sulfate, aluminum nitrate, aluminum silicate, aluminate such as sodium aluminate, and fluoroaluminum such as sodium fluoroaluminate. Moreover, it is also possible to supply through surface treatment of an aluminum-type metal.

<Aluminum ion scavenger>
As described above, the aluminum ion scavenger contained in the metal surface treatment composition of the present invention improves the stability of the metal surface treatment composition by generating some interaction with aluminum ions. Is. Moreover, a part can couple | bond with the zirconium ion in a metal surface treatment composition, it can also precipitate on the aluminum-type material surface, and the effect which improves adhesiveness with a coating film can also be acquired. Specific examples include polyitaconic acid, monosaccharide alcohol, and disaccharide alcohol.

  The content of the aluminum ion scavenger in the metal surface treatment composition of the present invention is preferably 50 ppm or more and 10,000 ppm or less, and more preferably 100 ppm or more and 1000 ppm or less. When the content is less than 50 ppm, the adhesiveness decreases because the content of the organic complex compound formed by the aluminum ion in the composite chemical conversion film and the aluminum supplement is small. When the amount is more than 10,000 ppm, the improvement in performance cannot be expected, which is disadvantageous in terms of cost. In addition, when an aluminum ion scavenger consists of 2 or more types, let those total amount be content of an aluminum ion scavenger.

[Polyitaconic acid]
Specific examples of polyitaconic acid include alkali metal salts and ammonium salts of polyitaconic acid in addition to polyitaconic acid itself. Furthermore, a polyitaconic acid-polymaleic acid copolymer having an itaconic acid segment, a polyitaconic acid copolymer such as a polyitaconic acid- (meth) acrylic acid copolymer, a polyitaconic acid-sulfonic acid copolymer, and alkali metals thereof Salts and ammonium salts can also be used. A homopolymer of polyitaconic acid is preferred. The molecular weight of the polyitaconic acid is, for example, 260 to 1000000, and preferably 1000 to 70000.

  When the polyitaconic acid is a copolymer, the content of the itaconic acid segment in the copolymer is regarded as an active ingredient as an aluminum ion scavenger. For example, when the metal surface treatment composition of the present invention contains 200 ppm of polyitaconic acid-polymaleic acid copolymer, and the mass ratio of itaconic acid and maleic acid in this copolymer is 1/1, aluminum The content of the ion scavenger is considered to be 200 ppm × 1/2 = 100 ppm.

  When the polyitaconic acid is a copolymer, the content of the itaconic acid segment in the copolymer is preferably 10% by mass or more, and more preferably 50% by mass or more. The effects of the present invention cannot be obtained with acrylic resins that do not contain an itaconic acid segment, such as polyacrylic acid, polymethacrylic acid, and other acrylic copolymers that do not contain itaconic acid.

[Monosaccharide alcohol]
Specific examples of the monosaccharide alcohol include sorbitol, mannitol, galactitol, xylitol and the like. Of these, sorbitol is particularly preferably used because the effects of the present invention are easily obtained.

[Disaccharide alcohol]
Specific examples of the disaccharide alcohol include maltitol and lactitol. Of these, maltitol is particularly preferably used because the effects of the present invention are easily obtained.

<PH>
The pH of the metal surface treatment composition of the present invention is preferably 2 or more and 5 or less. More preferably, it is 3 or more and 4.5 or less. When the pH is less than 2, the etching is excessive, and when the pH is more than 5, the etching is insufficient and the metal surface treatment composition becomes unstable. The pH can be adjusted by adding nitric acid when the pH is high, and adding ammonia, sodium hydroxide, potassium hydroxide or the like when the pH is low.

<Additives>
The metal surface treatment composition of the present invention may be one obtained by adding a predetermined amount of various additives within a range not impairing the effects of the present invention. For example, in addition to metal ions such as manganese, zinc, calcium, iron, magnesium, molybdenum, vanadium, titanium, silicon, surfactants, citric acid, gluconic acid, malonic acid, succinic acid, tartaric acid, phosphonic acid, etc. A metal salt or the like may be added.

<Film formation conditions>
As a liquid temperature at the time of forming a chemical conversion treatment film using the metal surface treatment composition of this invention, 30 to 70 degreeC is preferable. More preferably, it is 40 degreeC or more and 60 degrees C or less. When the treatment temperature is less than 30 ° C., the film formation reaction is slow and the treatment time becomes long, which is industrially disadvantageous. When the treatment temperature is more than 70 ° C., the stability of the aluminum ion scavenger is lowered. The treatment time is preferably 1 second or more and 60 seconds or less. More preferably, it is 2 seconds or more and 10 seconds or less. If it is less than 1 second, the film formation reaction time is insufficient, and it becomes difficult to form an appropriate chemical conversion film. If it exceeds 60 seconds, the treatment time is long, which is industrially disadvantageous.

<Chemical conversion film>
Coating of the metal surface treated metal material surface with the chemical conversion film is formed using a composition of the present invention, zirconium 2 mg / m ² or more 100 mg / m ² or less is preferable in terms of metal element. More preferably, it is 10 mg / m ² or more and 25 mg / m ² or less. If it is less than 2 mg / m ² , appropriate corrosion resistance cannot be obtained, and if it exceeds 100 mg / m ² , adhesion and corrosion resistance are not improved, resulting in high costs. Further, it is preferable that aluminum ion trapping agent is 20 mg / ^{m 2} or less 0.5 mg / ^{m 2} or more organic carbon content in terms derived from the aluminum ion trapping agent. More preferably, it is 1 mg / m ² or more and 10 mg / m ² or less. If it is less than 0.5 mg / m ² , appropriate adhesion cannot be obtained, and if it exceeds 20 mg / m ² , adhesion and corrosion resistance are not improved, resulting in high costs.

<Processing method>
The metal surface treatment composition of the present invention is used for pre-coating treatment of an aluminum-based metal. Examples of the aluminum metal include aluminum and aluminum alloys. It does not specifically limit as a surface treatment method, After performing a degreasing process and an etching process as needed, it can carry out by a spray process, an immersion process, etc., for example.

  The coating after the surface treatment with the metal surface treatment composition of the present invention is not particularly limited. For example, when the object is a food can, a can paint such as a vinyl chloride paint is applied. It is also possible to apply a laminating process by applying a laminating adhesive resin in addition to the coating.

<Aluminum-based metal surface treatment plate>
An aluminum-based metal surface-treated plate obtained by treating the above-described metal surface-treating composition on an aluminum-based metal plate also belongs to the scope of the present invention. In this case, an aluminum-based metal surface-treated plate is obtained by bringing the previous metal surface-treating composition into contact with at least one surface of the aluminum-based metal plate. As for the chemical conversion film present on the surface of the aluminum-based metal surface-treated plate, the contents already described are applied as they are.

  EXAMPLES Next, although an Example and a comparative example are given and this invention is demonstrated concretely, this invention is not limited only to these Examples.

<Metal surface treatment>
An aluminum alloy (5182 material) was prepared as an aluminum-based metal, and degreasing was performed by immersing in a 2% aqueous solution (65 ° C.) of a degreasing agent “SCL420N-2” (trade name) manufactured by Nippon Paint Co., Ltd. for 7 seconds. . After degreasing, it was washed with water and then immersed in a 2% aqueous sulfuric acid solution (50 ° C.) for 3 seconds for acid cleaning. After the acid cleaning, the substrate was washed with water, and then sprayed with each metal surface treatment composition shown in Examples and Comparative Examples. Then, after washing with water and dehydrating with a roll squeeze, it was dried under conditions of 80 ° C. × 60 seconds.

<Example 1>
Fluorozirconic acid, aluminum hydroxide, hydrofluoric acid, and polyitaconic acid (“PIA-728”, trade name, molecular weight of about 3000) manufactured by Iwata Chemical Industries, Ltd. as an aluminum ion scavenger, A metal surface treatment composition was obtained by adding 10 ppm of aluminum ions, 1 ppm of effective fluorine ions, and 200 ppm of aluminum ion scavenger, and adjusting the pH to 3.5 by adding ammonia.

<Examples 2 to 19>
In the same manner as in Example 1, Examples 2 to 19 were prepared by changing the blending amounts of the respective components as shown in Table 1.

<Example 20>
Example and formulation prepared in the same manner as in Example 1 except that itaconic acid-acrylic acid copolymer (manufactured by Nippon Pure Chemical Co., Ltd., “Julimer AC-50”, trade name) was used as the aluminum ion scavenger. It was set to 20.

<Example 21>
Example 21 was prepared and prepared in the same manner as in Example 1 except that D-sorbitol (Towa Kasei Kogyo Co., Ltd., “Sorbit”, trade name), which is a monosaccharide alcohol, was used as the aluminum ion scavenger. .

<Example 22>
As an aluminum ion scavenger, it was blended and prepared in the same manner as in Example 21 except that maltitol (Towa Kasei Kogyo Co., Ltd., “AMAMIR”, trade name), which is a disaccharide alcohol, was used instead of D-sorbitol. Example 22

<Comparative Example 1>
As shown in Table 2, Comparative Example 1 was prepared by blending and preparing in the same manner as in Example 1 except that none of zirconium ions, aluminum ions, and fluorine ions was blended.

<Comparative example 2>
Comparative Example 2 was prepared and prepared in the same manner as Example 1 except that no aluminum ion scavenger was added.

<Comparative Example 3>
A comparative example 3 was prepared by mixing and preparing in the same manner as in Example 1 except that aluminum ions were not blended.

<Comparative example 4>
Comparative Example 4 was prepared and prepared in the same manner as in Example 1 except that 200 ppm of phenol resin (manufactured by Showa Polymer Co., Ltd., “Shonol BRL-141B”, trade name) was used instead of the aluminum ion scavenger. did.

<Comparative Example 5>
Comparative Example 5 was prepared and prepared in the same manner as in Example 1 except that 200 ppm of polyacrylic acid (manufactured by Nippon Pure Chemical Co., Ltd., “Julimer AC10L”, trade name) was used instead of the aluminum ion scavenger.

<Comparative Example 6>
Comparative Example 5 was prepared and prepared in the same manner as in Example 1 except that 200 ppm of polymethacrylic acid (manufactured by Nippon Pure Chemical Co., Ltd., “AC30H”, trade name) was blended in place of the aluminum ion scavenger.

<Comparative Example 7>
Comparative Example 7 was prepared and prepared in the same manner as in Example 1 except that 200 ppm of tannic acid (manufactured by Sumitomo Dainippon Pharma Co., Ltd., “N Tannic Acid”, trade name) was used instead of the aluminum ion scavenger. .

<Comparative Example 8>
The chromium-based surface treatment composition phosphoric acid chromate (manufactured by Nippon Paint Co., Ltd., “Alsurf 407/47”, trade name) was used as Comparative Example 8.

<Sludge observation>
After treating 0.1 m ^{2 of} an aluminum alloy (5182 material) per liter of the metal surface treatment composition, the turbidity of the metal surface treatment composition was visually observed. The evaluation criteria were as follows. The results are shown in Tables 1 and 2.
○: No turbidity.
X: There is turbidity.

<Evaluation>
[Measurement of chemical film content]
The amount of zirconium deposited on the prepared chemical conversion film was measured using a fluorescent X-ray analyzer (manufactured by Shimadzu Corporation, “XRF1700”, trade name). The amount of aluminum ion scavenger adhering was measured as the amount of organic carbon derived from the aluminum ion scavenger using a total organic carbon measuring device ("RC-412", trade name, manufactured by LECO). The respective measured amounts are shown in Tables 1 and 2.

[Adhesion: Cross-cut adhesion test]
About the aluminum alloy which performed each said process, after apply | coating a vinyl chloride solvent-type paint with a bar coater so that it may become a dry coating film thickness of 12 micrometers, it is 260 degreeC * 30 second using an electric conveyor discharge | emission type oven. The drying conditions were as follows. Next, the prepared coated plate was subjected to a high-temperature and high-humidity test at 125 ° C. for 30 minutes, and then a cross-cut adhesion test was performed to visually observe the peeling rate. The evaluation criteria were as follows. The results are shown in Tables 1 and 2.
A: The peel rate is 5% or less.
○: The peeling rate is larger than 5% and smaller than 10%.
Δ: The peeling rate is 10% or more and less than 20%.
X: Peeling rate 20% or more.

<Corrosion resistance>
As a model juice corrosion resistance test, a vinyl chloride solvent-type paint was applied with a bar coater so that the dry coating film thickness was 12 μm, and then dried under a drying condition of 260 ° C. × 30 seconds using an electric conveyor discharge oven. I let you. Next, the cup was molded and immersed in model juice (1% citric acid, 1% NaCl), and then allowed to stand at 50 ° C. for 96 hours. After standing, the corrosion rate was evaluated by visually observing the corrosion rate. The evaluation criteria were as follows. The results are shown in Tables 1 and 2.
○: Corrosion rate of 10% or less.
Δ: Corrosion rate greater than 10% and less than 20%.
X: Corrosion rate 20% or more.

<Result>
As shown in Tables 1 and 2, all Examples have better adhesion, corrosion resistance, and sludge properties than Comparative Examples 1 to 7, and are excellent at a level equivalent to that of Comparative Example 8 using phosphoric acid chromate. The effect was confirmed.

Claims (3)

A metal surface treatment composition used for pre-coating treatment of an aluminum-based metal plate,
Fluorine ions, zirconium ions, aluminum ions, and, seen containing an aluminum ion trapping agent,
The aluminum ion scavenger is polyitaconic acid,
Containing an aluminum ion scavenger in an amount of 50 ppm or more and 10,000 ppm or less,
A metal surface treatment composition used in a method in which a surface of the aluminum-based metal plate is treated to form a chemical conversion film, and the chemical conversion film is washed with water and then dried . The fluorine ions 1ppm or 1000ppm or less as an active fluorine ion content, the zirconium ions 10ppm or 10000ppm or less and the aluminum ions in terms of metal element in an amount of 10ppm or 2000ppm hereinafter in terms of metal element, and, pH is 2 to 5 in which claim 1 Symbol placing the metal surface treatment composition. By bringing the metal surface treatment composition according to claim 1 or 2 into contact with at least one surface of an aluminum-based metal plate under conditions of a liquid temperature of 30 ° C. or more and 70 ° C. or less and a treatment time of 1 second or more and 60 seconds or less, Zirconium is 2 mg / m ² or more and 100 mg / m ² or less in terms of metal elements on the surface of the aluminum-based metal plate, and the aluminum ion scavenger is 0.5 mg / m ² or more in terms of organic carbon derived from the aluminum ion scavenger. An aluminum-based metal surface-treated plate on which a chemical conversion film containing 20 mg / m ² or less is formed.