JP5131893B2 - An aluminum-plated steel material with excellent resistance to discoloration during heating and corrosion resistance after heating, and its aqueous treatment chemicals. - Google Patents

Description

  The present invention is for environmentally friendly aluminized steel materials that do not contain chromate, fluorine compounds, or Mn compounds, V compounds, Mo compounds, organic inhibitors, etc. that may cause discoloration when heated. The present invention relates to an aluminum-plated steel material having a corrosion-resistant film formed thereon by a surface treatment chemical and its aqueous treatment chemical.

  Conventionally, aluminum-plated steel has been widely used for home appliances used in environments where heat is applied, such as toasters, rice cookers, etc. This is the beauty of the appearance of aluminum-plated steel and excellent heat resistance. This is because the color tone does not change even when heated. Further, these aluminum plated steel materials are generally subjected to chromate treatment for the purpose of preventing rusting and ensuring corrosion resistance in the customer's use process. However, due to the recent strengthening of environmental regulations, the use of chromate has become virtually impossible, and there has been a strong demand for the development of a new coating that does not contain chromate, and a great deal of effort has been made over the past decade.

  For example, JP-A-6-146003 (Patent Document 1) discloses a surface-treated metal material provided with a molybdic acid-based film. Since the molybdic acid discolors with heating, this film is unsuitable for use in an environment where heat is applied. Japanese Patent Application Laid-Open No. 2002-30460 (Patent Document 2) and Japanese Patent Application Laid-Open No. 2004-232040 (Patent Document 3) disclose at least one selected from vanadium compounds and zirconium, titanium, molybdenum, tungsten, manganese, and cerium compounds. Although the film | membrane which provided the film | membrane containing the metal compound containing a kind of metal is disclosed, since a vanadium compound discolors with a heating, it is unsuitable for the use used in the environment where heat is added.

  Japanese Patent Laid-Open No. 9-20984 (Patent Document 4) discloses a treatment agent for an aluminum-containing metal material containing a titanium compound, phosphoric acid and fluoride. This treatment chemical contains fluorine and is not preferable in the environment, and does not exhibit sufficient corrosion resistance because an effective corrosion inhibitor (inhibitor) is not added. As another attempt, JP-A-8-73775 (Patent Document 5) and JP-A-9-241576 (Patent Document 6) disclose treatment methods using various types of silane coupling agents. Although these treatments exhibit corrosion resistance to some extent in a non-heated state, the silane coupling agent decomposes with heating and discolors, and since the corrosion inhibiting effect is lost, the corrosion resistance is extremely lowered.

  As a similar attempt, JP-A-10-1789 (Patent Document 7) and JP-A-10-60233 (Patent Document 8) describe phenolic, polyester, polycarbonate, acrylic resin, epoxy resin, polyolefin resin, and polyurethane resin. An antirust treatment method mixed at a specific ratio is disclosed. These treatments are also the same as the above-described silane coupling agent treatment, and do not exhibit sufficient performance due to discoloration and corrosion resistance deterioration accompanying decomposition of organic substances.

On the other hand, JP-A- 55-31113 (Patent Document 9) discloses a water-soluble titanium compound, an acidic metal surface treatment agent containing a water-soluble zirconium compound, 2-6 linked phosphate esters of myo-inositol, and silica. Is disclosed. Since this does not contain components that decompose and discolor and change in performance with heating, discoloration after heating can be avoided, but sufficient corrosion-inhibiting components have not been added, so corrosion resistance after heating was not sufficient.
(JP-A-6-146003) JP 2002-30460 A) (Japanese Patent Laid-Open No. 2004-232040) JP-A-9-20984) JP-A-8-73775) JP-A-9-241576) (JP-A-10-1789) (Japanese Patent Laid-Open No. 10-60233) JP-A-55-31113)

  The present invention does not contain chromate, which is restricted in use due to environmental friendliness, has not only corrosion resistance at room temperature, but also excellent resistance to discoloration during heating, and exhibits an anti-corrosion resistance after heating, and its aqueous treatment The drug is provided.

  As a result of intensive studies on means for solving the problems of the prior art, the present inventors have obtained a specific titanium compound and a zirconium compound, a specific myo-inositol phosphate, and a salt thereof, And an aluminum-plated steel material with excellent resistance to discoloration at the time of heating and corrosion resistance after heating by applying a film on the aluminum plating using a treatment agent mixed with silica and a specific ratio The present inventors have found that an aqueous treatment chemical can be obtained and have completed the present invention.

The gist of the invention is (1) (A) at least one or more of titanium compounds and zirconium compounds, (B) 2-6 linked phosphate esters of myo-inositol, and alkali metals thereof salts, alkaline earth metal salts, and ammonium least one or more of the salt from the (C) silica mosquitoes, (D) o (hydrogen) phosphate compound, meta-phosphate compound, polyphosphoric acid (hydrogen) compound A composition containing 0.03 to 0.5 in a mass ratio in terms of P in (D) with respect to a metal equivalent 1 in (A), and having a pH of 8 to 11 Using a film whose mass ratio of (A) in metal equivalent (Zr + Ti) :( B) :( C) is 1: 0.2 to 1.7: 0.2 to 5 in metal equivalent in (A) characterized in that the 30~1000mg / m ² applied in an amount Tarnish resistance during thermal excellent aluminized steel material after heating corrosion resistance.

( 2 ) The aluminum plated steel material having excellent discoloration resistance during heating and corrosion resistance after heating according to (1) , wherein (B) is 6 phosphate esters.
( 3 ) The plating layer composition of the aluminum-plated steel material is Al: 70 to 97% by mass, Si: 3 to 15% by mass, and the resistance to heating during heating according to (1) or (2) above Aluminum-plated steel with excellent discoloration and corrosion resistance after heating.

(4) (A) at least one or more of titanium compounds and zirconium compounds, (B) 2 to 6 bonded phosphates of myo-inositol, and alkali metal salts, alkaline earth metal salts, and ammonium thereof At least one or more of the salts, (C) silica and water , (D) at least one of the ortho (hydrogen) phosphate, metaphosphate, and polyphosphate (hydrogen) compounds is the metal of (A) It is a composition containing 0.03 to 0.5 component in a mass ratio in terms of P of (D) with respect to the conversion amount 1 and has a pH of 8 to 11 for heating resistance and corrosion resistance after heating. It is an excellent water treatment chemical for aluminized steel.

  As described above, the treatment agent of the present invention is an environment-friendly aluminized steel sheet that does not contain chromium, fluorine compounds, or Mn, V, Mo, organic inhibitors, etc. that cause discoloration when heated. The aluminum-plated steel sheet on which a corrosion-resistant film is formed by a surface treatment agent is very good in heat discoloration and corrosion resistance after heat resistance compared to conventional films. It is extremely valuable.

Below, the structure of this invention is demonstrated in detail.
The titanium compound and zirconium compound (A) contained in the composite coating on the aluminum-plated steel material of the present invention are formed by applying and drying a treatment agent containing a titanium compound and a zirconium compound. Titanium compounds and zirconium compounds to be included in the treatment agent are not particularly limited, but titanium compounds include potassium potassium oxalate, titanyl sulfate, titanium chloride, titanium lactate, titanium isopropoxide, isopropyl titanate, titanium ethoxide. , Titanium 2-ethyl-1-hexanolate, tetraisopropyl titanate, tetra-n-butyl titanate, titania sol and the like.

  Of these, titania sol and titanium lactate are preferable. Examples of the zirconium compound include zirconyl nitrate, zirconyl acetate, zirconyl sulfate, zirconyl ammonium carbonate, potassium zirconium carbonate, sodium zirconium carbonate, zirconium acetate and the like. Of these, zirconium compounds containing zirconium carbonate complex ions are preferred.

Is not particularly restricted but includes zirconium compounds containing zirconium carbonate complex ions, zirconium carbonate complex ions _{[Zr (CO 3) 2 (OH} ) 2 ] ^2- or _{[Zr (CO 3) 3 (OH} ) ] ³ Ammonium salt, potassium salt, sodium salt and the like. However, titanium hydrofluoric acid, zirconium hydrofluoric acid, or a salt thereof containing a fluorine compound does not correspond to a titanium compound or a zirconium compound contained in the film of the present invention.

The content of titanium compound and zirconium compound in the composite film is required to be 30 to 1000 mg / m ² as titanium and zirconium per side, and more preferably 50 to 800 mg / m ² . When the content of titanium compound and zirconium compound in the composite film is less than 30 mg / m ² per side as titanium and zirconium, the effect of improving corrosion resistance, discoloration during heating, and corrosion resistance after heating is poor, and exceeds 1000 mg / m ² Is not desirable because the film appearance is uneven.

  In addition, 2 to 6 linked phosphoric esters of myo-inositol in the composite film are myo-inositol diphosphate, myo-inositol triphosphate, myo-inositol tetraphosphate, myo-inositol pentane phosphate. , Myo-inositol hexane phosphate ester, an alkali metal salt, an alkaline earth metal salt, and an ammonium salt of 2 to 6 linked phosphate esters of myo-inositol are those of myo-inositol. These are salts in which some or all of the six bonded phosphate esters are substituted with metals such as Na, K, Li, Mg, Ca, Sr, Ba, or ammonium. In addition, inositol (myo-inositol), phytin (myo-inositol hexaphosphate ester Mg5-Na-K), tannic acid and the like can be used in combination.

  The addition amount of this myo-inositol compound needs to be 0.2 to 1.7, more preferably 0.8 to 1.5, with respect to the metal equivalent (Ti + Zr) of (A). When this ratio is less than 0.2, the corrosion inhibition effect is poor and the corrosion resistance improving effect is poor, and not only the corrosion resistance after heating but also the corrosion resistance when not heated is insufficient. On the other hand, when this ratio exceeds 1.7, the influence of alteration of the myo-inositol compound accompanying heating becomes significant, and heat resistance and corrosion resistance after heating cannot be ensured.

  Moreover, the silica compound contained in the composite film is a component necessary for ensuring film soundness and adhesion to the steel sheet, and is formed by applying and drying a treatment agent containing the silica compound. Although it does not specifically limit as a silica compound contained in a processing chemical | medical agent, A water dispersible silica compound is more preferable. Examples of the water-dispersible silica compound include liquid phase colloidal silica and gas phase silica. The liquid phase colloidal silica is not particularly limited, but SNOWTEX C, SNOWTEX O, SNOWTEX N, SNOWTEX S, Snow Tex UP, Snowtex PS-M, Snowtex PS-L, Snowtex 20, Snowtex 30, Snowtex 40 (all manufactured by Nissan Chemical Industries), Adelite AT-20N, Adelite AT-20A, Adelite AT-20Q ( Asahi Denka Kogyo Co., Ltd.).

  The gas phase silica is not particularly limited, and examples thereof include Aerosil 50, Aerosil 130, Aerosil 200, Aerosil 300, Aerosil 380, Aerosil TT600, Aerosil MOX80, Aerosil MOX170 (all manufactured by Nippon Aerosil).

  The addition amount of the silica compound needs to be 0.2 to 5.0 with respect to the metal equivalent amount (Ti + Zr) of (A), and more preferably 0.8 to 2.0. When this ratio is less than 0.2, a sufficient film cannot be obtained and necessary adhesion cannot be ensured, and the corrosion resistance becomes insufficient. On the other hand, if this ratio exceeds 5, the effect of the myo-inositol compound, which is a corrosion-inhibiting component, is not sufficiently exerted, and in particular, the corrosion resistance after heating cannot be ensured.

  The phosphoric acid compound contained in the composite film is added for the purpose of further improving the corrosion resistance of the film. These ammonium salts, sodium salts, calcium salts, potassium salts and the like in which some or all of the hydrogen ions have been replaced can be used alone or in combination. It is necessary that the addition amount of the phosphoric acid compound is 0.03 to 0.5 in terms of mass ratio in terms of P with respect to the metal conversion amount (Ti + Zr) of (A), and more preferably 0.06 to 0.3. It is. When this ratio is less than 0.03, the effect of improving corrosion resistance is poor, and when it exceeds 0.5, the treatment chemical becomes unstable, and precipitates are generated in the treatment chemical in a relatively short time. Moreover, even if the solution is applied in a stable state, sufficient film adhesion cannot be ensured. A wetting agent or the like may be added so that the treatment chemical can be uniformly applied.

  When a metal coating agent is applied and dried to form a composite film, a plating component (Al, Si, Fe added metal, etc.) may be incorporated into the film, but this does not impair the gist of the present invention, The same applies when the plating component is concentrated near the plating surface of the film. Furthermore, even if the composite film is formed unevenly on the plating surface, the gist of the present invention is not impaired.

  Next, the aluminum plating layer will be described. Since the composite film of the present invention is formed on Al and suppresses anodic and cathodic reactions of corrosion, if the plating layer composition is less than 70% by mass of Al, sufficient corrosion resistance cannot be exhibited. Therefore, the lower limit of Al of the plating layer is set to 70% by mass. Furthermore, what is Al: 70-97 mass% and Si: 3-15 mass% is preferable. The purpose of adding Si is to suppress excessive growth of the alloy layer, which is a problem with Al-based plated steel materials. If the Si content is less than 3%, the alloy layer grows too much and the corrosion resistance after molding decreases. On the other hand, if the Si amount increases too much, a coarse Si primary crystal is crystallized and decreases the corrosion resistance after molding. is there.

  The impurity element can be a trace amount of Fe, Ni, Co, or the like. If necessary, Mg, Sn, Misch metal, Sb, Zn, Cr, W, V, Mo, etc. may be added. There are no particular restrictions on the method of manufacturing the aluminum-plated steel material, but hot-dip plating, electroplating, and vapor deposition plating by the flux flux plating, Sendzimer method, all-radiant method, or the like are desirable.

  In the present invention, the steel component of the base material used for the aluminum-plated steel material is not limited. Examples of the steel type include IF steel, Al-k steel, Cr-added steel, stainless steel to which Ti, Nb, B, and the like are added. Examples include high tensile steel and electrical steel sheets. IF steel and B additive are used for applications that require deep drawability and secondary work cracking resistance such as fuel tanks, Al-k steel is used for household appliances, and electromagnetic steel sheets are used for electromagnetic shielding applications. desirable.

  It is preferable to apply and dry the treatment agent of the present invention after washing the surface of these plating materials by alkali degreasing, pickling or the like. Although it does not specifically limit as a coating method of a processing chemical | medical agent, A roll coater method, a dipping method, a spray method, an electrostatic coating method etc. can be used. It is preferable to apply | coat by these methods and to dry at 50-200 degreeC as reach | attained temperature, and to provide a film.

By setting the pH of the treatment liquid to 8 or more and 11 or less, it is possible to appropriately maintain an etching property with the material and secure a good film. If the pH is less than 8 , the reactivity with the material and the etching property become small, and it becomes difficult to ensure perfect film adhesion. On the other hand, if the pH exceeds 11, the film has a very poor etching property and a slightly inferior uniformity.

Below, the structure of this invention is demonstrated in detail.
Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. In addition, these Examples are described for description of this invention, and do not limit this invention at all.
(1) Preparation of aluminum-plated steel materials Steels having the components shown in Table 1 and Table 2 are melted by a normal converter-vacuum degassing treatment to form a steel slab, followed by hot rolling and cold rolling under normal conditions. A 0.8 mm steel plate was obtained. The steel sheet was subjected to Al-Si plating in which the composition was varied in a NOF-RF type hot dipping line. In all cases, the plating adhesion amount was adjusted to about 40 g / m ² . The plated steel sheet thus produced was used as a test material for aluminum-plated steel.

(2) Degreasing treatment Each of the above test materials was degreased (concentration 20 g / l, temperature 60 ° C., sprayed for 20 seconds) with a silicate alkaline degreasing agent Fine Cleaner 4336 (registered trademark: manufactured by Nihon Parkerizing Co., Ltd.). Then, it was washed with tap water.
(3) Preparation of treatment chemicals Titanium compound / zircon compound, myo-inositol, silica, phosphoric acid compound are blended with chemicals as shown in Table 1 in various ratios, and an alkaline solution such as an amine is prepared so as to have each pH. A treatment agent was prepared using ammonium, sodium, potassium, and the like. For comparison, a drug containing a metal such as Mo and V as an inhibitor and a drug using a silane coupling agent were also prepared with reference to conventional patent documents.

(4) Application of treatment chemicals Each treatment chemical prepared as described above was applied onto each test plate with a bar coater and dried at a final plate temperature of 80 ° C. The coating amount (g / m ² ) was adjusted by appropriately adjusting the solid content concentration of the treatment chemical.
[Performance evaluation items and evaluation methods]
(A) Treated drug stability The prepared drug was stored at a constant temperature of 40 ° C. for 40 days, the properties of the drug were visually confirmed, and the stability was judged according to the following criteria.
○: Maintains a uniform state ×: Precipitate is generated and is unsuitable as a drug (b) Film appearance The film appearance after drug application / drying was visually judged according to the following criteria.
A: Appearance is beautiful and extremely uniform film is formed. ○: Appearance is uniform film. ×: Appearance is in a powdered state or mottled and does not appear as a film.

(C) Film adhesive The coated and dried steel material was extruded 7 mm using an Erichsen testing machine, and then the extruded film was peeled off with cellophane tape (registered trademark) and judged according to the following criteria.
◎: No film peeling ○: Film peeling less than 1% ×: Film peeling 1% or more (d) Flat plate corrosion resistance chemical applied and subjected to salt spray test (JIS-Z2371) without processing the dried steel material, 72 hours later The white rust generation area ratio was measured and evaluated according to the following criteria.
(Evaluation criteria)
◎: No rust occurrence ○: Rust occurrence rate less than 2% △: Less than 2% to less than 5% ×: 5% or more (e) Processed part corrosion resistant chemical coated and dried steel material is extruded 7mm using Erichsen test machine and then brine It used for the spray test (JIS-Z2371), the white rust generation | occurrence | production area ratio 72 hours after was measured, and the following references | standards evaluated.
(Evaluation criteria)
◎ +: No rust generation ◎: Rust generation rate less than 2% ○: 2% to less than 5% △: 5% to less than 30% ×: 30% or more (f) The sample was subjected to a heat treatment at 300 ° C. for 200 hours in an air atmosphere. The surface appearance change before and after heating was measured with a color difference meter. In measurement, L * × a ** × b * was measured, and ΔE * was calculated from the following equation from the change before and after the measurement. ΔE * = √ (ΔL * × ΔL * + Δa * × Δa * + Δb * × Δb *)
The obtained ΔE * was evaluated according to the following criteria.
(Evaluation criteria)
◎: Less than 2 ○: Less than 2-3 △: Less than 3-4 ×: 4 or more (g) Corrosion resistance after heating Salt water spraying without processing the steel material after the above heat treatment (leaving at 300 ° C. for 200 hours in the air atmosphere) It used for the test (JIS-Z2371), the white rust generation | occurrence | production area ratio after 72 hours was measured, and the following references | standards evaluated.

(Evaluation criteria)
◎: Rust generation rate less than 2% ○: 2% to less than 5% △: 5% to less than 30% ×: 30% or more

実施例及び比較例の処理薬剤組成・付与量、用いためっき鋼材、および評価結果を表３に示した。
チタン化合物／ジルコニウム化合物（Ａ）と、ｍｙｏ−イノシトール（Ｂ）とシリカ（Ｃ）を本発明の比率を保って皮膜を付与したアルミめっき鋼板は、薬剤安定性、皮膜外観、皮膜密着性も良好で十分な耐食性を保持し、さらに耐熱試験後も皮膜外観及び耐食性も良好であった。さらに（Ｄ）成分を添加することで、耐熱後の耐食性が更に良好となる。特にめっき層組成、処理薬剤のｐＨも適正な範囲に保った本発明例Ｎｏ．５は全ての項目において極めて良好な性能を発揮する。一方処理薬剤の比率は適正範囲内であるが、めっき層組成、あるいは処理薬剤のｐＨのいずれかが適正範囲から外れた場合（本発明例Ｎｏ．６からＮｏ．８）は比較例Ｎｏ．１０に示すクロメート材より良好な性能は発揮するものの実施例５より若干性能に劣る。

Table 3 shows the treatment chemical composition and the applied amount, the plated steel materials used, and the evaluation results of Examples and Comparative Examples.
An aluminum-plated steel sheet coated with a titanium compound / zirconium compound (A), myo-inositol (B), and silica (C) while maintaining the ratio of the present invention has good chemical stability, film appearance, and film adhesion. In addition, sufficient corrosion resistance was maintained, and the film appearance and corrosion resistance were also good after the heat test. Furthermore, the corrosion resistance after heat resistance becomes further favorable by adding (D) component. In particular, the plating layer composition and the pH of the treating agent were kept within the proper ranges of the inventive examples No. 5 exhibits extremely good performance in all items. On the other hand, the ratio of the treatment chemical is within the proper range, but when either the plating layer composition or the pH of the treatment chemical is out of the proper range (Invention Examples No. 6 to No. 8 ), Comparative Example No. Although the performance better than the chromate material shown in FIG. 10 is exhibited, the performance is slightly inferior to that of Example 5 .

In contrast, in the comparative example in which the ratio of each component of the treatment chemical was out of the range, the corrosion resistance, thermal discoloration after heat resistance, and corrosion resistance were inferior, and the aluminized steel material was not at a level that could withstand practical use.
Comparative Example No. 1 and no. In No. 2, the compounding ratio of the drug is appropriate, but the applied amount of the film is inappropriate and sufficient performance is not exhibited. Comparative Example No. 3-No. No. 7 is a case where the compounding ratio of the drugs is inappropriate. 3, no. 4 is component B, comparative example No. 5, no. 6 is component C, comparative example No. No. 7 has an inadequate blending ratio of component D, and none of the performance has been demonstrated sufficiently.

Comparative Example No. Although 8 is a case where Mo acid is used with reference to Patent Document 1, discoloration during heating cannot be prevented. Comparative Example No. 9 is a case where a silane coupling agent is used with reference to Patent Document 5, but the discoloration resistance during heating and the corrosion resistance after heating are insufficient . Ratio Comparative Examples No. Reference numeral 10 denotes a chromate treatment, which exhibits sufficient performance, but has a problem in environmental compatibility.

Claims (4)

(A) At least one or more of titanium compounds and zirconium compounds, (B) 2-6 linked phosphate esters of myo-inositol, and alkali metal salts, alkaline earth metal salts, and ammonium salts thereof at least one or more of the, (C) silica mosquitoes, (D) o (hydrogen) phosphate compound, meta-phosphate compound, in terms of metal amount of at least one from among polyphosphoric acid (hydrogen) compound (a) 1 is a composition containing 0.03 to 0.5 in a mass ratio in terms of P of (D) with respect to 1, and using a treatment agent having a pH of 8 to 11, a metal equivalent amount of (A) ( Zr + Ti): (B): (C) the mass ratio of 1: 0.2-1.7: 0.2-5 was given 30-1000 mg / m < ² > by the metal conversion amount of (A). Excellent resistance to discoloration during heating and corrosion resistance after heating Aluminum-plated steel. The aluminum-plated steel material having excellent discoloration resistance during heating and corrosion resistance after heating according to claim 1, wherein (B) is six phosphate esters. The plating layer composition of the aluminum-plated steel material is Al: 70 to 97 mass%, Si: 3 to 15 mass%, discoloration resistance during heating and corrosion resistance after heating according to claim 1 or 2 Excellent aluminized steel material. (A) At least one or more of titanium compounds and zirconium compounds, (B) 2-6 linked phosphoric esters of myo-inositol, and alkali metal salts, alkaline earth metal salts, and ammonium salts thereof (C) Silica and water , (D) Ortho (hydrogen) phosphate compound, metaphosphate compound, polyphosphoric acid (hydrogen) compound at least one of (A) metal equivalent 1 (D) is a composition containing 0.03 to 0.5 component in a mass ratio in terms of P , and has a pH of 8 to 11 and excellent in resistance to discoloration during heating and corrosion resistance after heating. Aqueous treatment agent for plated steel.