JP4291204B2 - Chromate-free surface-treated Al-Zn alloy-plated steel sheet with excellent corrosion resistance and method for producing the same - Google Patents

Description

  The present invention relates to a surface treatment material for an Al-Zn alloy-plated steel sheet that is mainly used unpainted in applications in the field of building materials and home appliances, in particular, a high Al-Zn-based material represented by a so-called 55% Al-Zn alloy-plated steel sheet The present invention relates to a chromate-free surface treatment material suitable for alloy-plated steel sheets and containing no Cr in the film.

  The high Al-Zn alloy-plated steel sheet represented by the so-called 55% Al-Zn alloy-plated steel sheet has a beautiful plating appearance and is excellent in corrosion resistance. Also, as home appliances, for example, they are used without coating on the back plate of a refrigerator. In these uses, the plated steel sheet needs long-term corrosion resistance, and is required to have excellent adhesion and corrosion resistance even when exposed to a humid environment. In addition, in the case of building materials, the plated steel sheet is formed by roll forming, so it is required that the plating is not picked up by the roll (that is, the roll forming property is good). The appearance after press molding must be such that it does not blacken by sliding with the mold. Furthermore, when applied to a roofing material, adhesion when bonded to a heat insulating material called pef, particularly adhesion in a wet environment due to moisture or the like, is required.

Conventionally, such applications have been dealt with by forming a surface treatment layer containing an organic resin and a chromium compound containing Cr ⁶⁺ on the plating surface (for example, Patent Documents 1 to 3). However, on the other hand, recently, regulation of Cr is progressing from the viewpoint of environmental impact, and accordingly, surface treatment is becoming chromate-free. Further, Cr ³⁺ is harmless, but when actually used in the market, it is difficult to distinguish between Cr ⁶⁺ and Cr ³⁺ in the film. From such a background, a chromate-free film that does not contain a Cr compound and has excellent performance such as corrosion resistance comparable to chromate treatment is strongly desired.
Japanese Patent Publication No. 1-53353 Japanese Patent Publication No.4-2672 Japanese Patent Publication No. 6-146001

  Among them, many techniques for forming a thin film on a plating surface by a method such as dipping, coating, electrolytic treatment using a treatment liquid containing a vanadium compound as a component replacing chromium are disclosed. Specifically, (a) a method of treating with a paint mainly containing phosphate ions and vanadate ions (for example, Patent Documents 4 and 5), (b) an organic resin, a thiocarbonyl group-containing compound, and a vanadium compound (Patent Document 6), (c) A method of treating with a surface treatment agent containing a specially modified phenolic resin, a vanadium compound, and a metal compound such as zirconium or titanium (Patent Document 7), (d ) A method of performing treatment with a surface treatment solution containing a vanadium compound, a zirconium compound, a titanium compound and the like (Patent Document 8).

  JP-A-1-92279   JP-A-1-131281   JP 2000-248380 A   JP 2001-181860 A   JP 2002-30460 A

  However, since the methods of Patent Document 4 and Patent Document 5 are mainly aimed at the rust prevention effect by the pentavalent vanadium compound, a large anticorrosion effect cannot be obtained. In the case of Patent Document 6, the corrosion resistance improving effect is exhibited by a compound containing a thiocarbonyl group, and the vanadium compound is mainly a pentavalent vanadium compound. . Also in Patent Document 7, the specially modified phenol resin is most effective in corrosion resistance, and the effect of metal salts such as vanadium and zirconium is small, and it cannot be said that the corrosion resistance is sufficient as compared with the chromate-treated film. Further, in the case of Patent Document 8, a composite film of a 2-5 pentavalent vanadium compound and a zirconium compound or a titanium compound is formed. By using a 2-4 tetravalent vanadium compound, the solubility of the film is to some extent. However, it has not reached the level of corrosion resistance until it is applied to a high Al—Zn alloy-plated steel sheet that requires particularly high corrosion resistance.

Thus, the conventional chromate-free surface-treated film cannot provide corrosion resistance comparable to the chromate-treated film conventionally used for high Al—Zn alloy-plated steel sheets.
Accordingly, the object of the present invention is to provide a chromate-free surface of an Al-Zn alloy-plated steel sheet having excellent corrosion resistance comparable to that of a surface-treated material made of a chromate-treated film, and excellent performance such as appearance quality, workability, and water adhesion. It is in providing a processing material and its manufacturing method.

The features of the present invention for solving the above-described problems are as follows.
[1] A vanadium compound (A) having a tetravalent valence on the surface of the plated film of an Al-Zn based alloy plated steel sheet having an Al-Zn based alloy plated film containing 25 to 75% by mass of Al, phosphorus An acid or / and phosphoric acid compound (B), a silane compound (C) having an epoxy group or / and an amino group, and an organic resin (D) comprising a water-soluble organic resin or / and a water-dispersible organic resin The vanadium compound (A) is composed of a vanadium sulfate oxide or a vanadate reduction product, and the amount of adhesion of the vanadium compound (A) in terms of metal V is 1 to 100 mg / m ² , the organic resin (D). A chromate-free surface-treated Al—Zn alloy-plated steel sheet excellent in corrosion resistance, characterized in that it has a surface-treated film having an adhesion amount of 0.5 to 5 g / m ² .

[2] A vanadium compound (A) having a tetravalent valence on the surface of the plated film of the Al-Zn based alloy plated steel sheet having an Al-Zn based alloy plated film containing 25 to 75% by mass of Al, phosphorus An acid or / and phosphoric acid compound (B), a silane compound (C) having an epoxy group or / and an amino group, and an organic resin (D) comprising a water-soluble organic resin or / and a water-dispersible organic resin Chromate-free surface-treated Al with excellent corrosion resistance, characterized in that the vanadium compound (A) as a main component is coated with a treatment solution comprising a vanadium sulfate oxide or vanadate reduction product, and then dried without being washed with water. -Manufacturing method of Zn type alloy plating steel plate.

[3] A vanadium compound (A) having a valence of 4 and phosphoric acid on the surface of the plated film of an Al-Zn based alloy plated steel sheet having an Al-Zn based alloy plated film containing 25 to 75% by mass of Al. Alternatively, after applying a treatment liquid (ii) containing the phosphoric acid compound (B) as a main component and the vanadium compound (A) comprising a vanadium sulfate oxide or a vanadic acid reduction product, drying without washing with water. Furthermore, after applying a treatment liquid (b) whose main component is an organic resin (D) made of a water-soluble organic resin and / or a water-dispersible organic resin to the upper part, the treatment liquid is dried without washing, (A) or / and the treatment liquid (b) contains a silane compound (C) having an epoxy group or / and an amino group, and is a chromate-free surface-treated Al—Zn system having excellent corrosion resistance alloy Manufacturing method of plated steel sheet.

  According to the present invention, it is possible to stably obtain a chromate-free surface-treated Al—Zn alloy-plated steel sheet having excellent corrosion resistance and excellent appearance quality, workability and water resistance.

  The plated steel sheet used as the base of the chromate-free surface-treated Al—Zn alloy-plated steel sheet of the present invention is an Al—Zn-based alloy plated steel sheet containing 25 to 75 mass% of Al in the plating film, so-called 55% Al—Zn. An alloy-plated steel sheet is known as the most typical one. Usually, this type of plating film contains Si in an amount of 0.5 mass% or more of the Al amount. In addition, the so-called 55% Al—Zn alloy-plated steel sheet is usually an Al—Zn-based alloy plated steel sheet in which Al is contained in an Al—Zn alloy plating film in an amount of about 50 to 60 mass% (in the following description, “high The term “Al—Zn alloy-plated steel sheet” refers to an Al—Zn alloy-plated steel sheet having the above-mentioned Al content), and the plating film usually contains about 1 to 3 mass% of Si.

In the present invention, an Al-Zn alloy-plated steel sheet having an Al content in the plating film of 25 to 75 mass% is targeted, and in this range of Al content, particularly excellent corrosion resistance (red rust resistance) is obtained. Because it is. However, in this plated steel sheet, as a problem derived from the fact that the plating film contains a lot of Al, black rust is generated when corrosion occurs in Al, and the appearance quality of the rust-proofing material is remarkably high against red rust. There is a difficulty that it is damaged. In addition, when this plated steel sheet is used without coating, it is preferred that the appearance is as plated, so that the surface is not significantly smoothed by the skin pass, so that the plated surface remains finely uneven. It has become. In this state, for example, when subjected to roll forming, there is a problem in terms of quality that the plating surface is galling due to contact with the roll and causes damage to the roll, and the appearance after molding is inferior. Therefore, in order to eliminate these, it is necessary to form a film further on the plating surface.
As will be described below, the characteristic improvement effect according to the present invention is remarkably obtained in an Al—Zn alloy-plated steel sheet having an Al content of 25 to 75 mass% in the plating film. -A particularly remarkable characteristic improvement effect is obtained in a Zn-based alloy-plated steel sheet.

Next, the surface treatment film formed on the surface of the Al—Zn alloy plating film will be described.
In the present invention, the surface treatment film formed on the surface of the Al—Zn alloy plating film does not contain a chromium compound, and has a tetravalent valence vanadium compound (A) and phosphoric acid or / and a phosphoric acid compound. The main component is (B), a silane compound (C) having an epoxy group or / and an amino group, and an organic resin (D) made of a water-soluble organic resin or / and a water-dispersible organic resin.

  In order to improve the corrosion resistance of an Al—Zn alloy-plated steel sheet (particularly, a high Al—Zn alloy-plated steel sheet) targeted by the present invention, a Zn-plated steel sheet, a low Al—Zn-based alloy plated steel sheet (for example, 5 % Al—Zn alloy-plated steel sheet) and Al-based plated steel sheet, it is necessary to improve the corrosion resistance of both Al and Zn in the plating film. As a result of examining the anticorrosive effect of the inorganic compound, the elements belonging to the periodic table 5A (V, V, etc.) for Al—Zn alloy plating, particularly high Al—Zn alloy plating, to which the present invention is applied. It has been found that Nb, Ta) compounds have a significant anticorrosive effect. The remarkable anticorrosion effect by the compounds of these specific elements is peculiar to Al—Zn alloy plating (particularly, high Al—Zn alloy plating) targeted by the present invention. Is an unacceptable effect. That is, in other plating species such as Zn plating, there is no difference in the effect between the above compounds and compounds of other elements not belonging to the periodic table 5A.

  For the above reasons, it is preferable to use a compound of an element belonging to the periodic table 5A in the surface treatment film, but among them, the Ta-based compound and the Nb-based compound are very expensive compared to the V-based compound. V-based compounds are most promising in terms of practicality (anticorrosive effect and cost). Thus, as a result of investigations focusing on this vanadium compound, it was found that among the vanadium compounds, there is a significant difference in the corrosion resistance obtained by the valence of vanadium. Specifically, pentavalent vanadium compounds (for example, ammonium vanadate, sodium vanadate, etc.) do not have a significant effect of improving corrosion resistance, whereas tetravalent vanadium compounds (for example, vanadium sulfate, in aqueous solution) It was found that the corrosion resistance of the pentavalent vanadium compound was significantly improved. Further, the tetravalent vanadium compound has a characteristic that it has a lower solubility than the pentavalent vanadium compound, and can form a film having excellent water resistance. For this reason, the surface-treated film containing the pentavalent vanadium compound dissolves V when wetted with water and the appearance quality is remarkably deteriorated. However, the surface-treated film containing the tetravalent vanadium compound has improved water resistance and appearance. A quality improvement effect is recognized. For the above reasons, in the present invention, the vanadium compound (A) having a tetravalent valence is added to the surface treatment film.

  Examples of vanadium compounds having a tetravalent valence include vanadium oxide, hydroxide, sulfide, sulfate, carbonate, halide, nitride, fluoride, carbide, cyanide (thiocyanide), and these A salt etc. are mentioned, These 1 type (s) or 2 or more types can be used. Specific examples include vanadic acid reduction products obtained by reducing pentavalent vanadium compounds in a vanadium sulfate oxide aqueous solution.

The reason for adding phosphoric acid or / and a phosphoric acid compound (B) in the surface treatment film is that the anticorrosion effect of the tetravalent vanadium compound is further enhanced by adding phosphoric acid or / and the phosphoric acid compound. Because it can.
Examples of phosphoric acid and phosphoric acid compounds include orthophosphoric acid, pyrophosphoric acid, polyphosphoric acid, metaphosphoric acid, etc., metal salts of phosphoric acid and one or more metals such as Mg, Zn, Ni, Co, etc. 1 type (s) or 2 or more types of these can be used.

  The reason why the corrosion resistance is drastically improved by adding phosphoric acid or / and the phosphoric acid compound (B) together with the tetravalent vanadium compound (A) is not necessarily clear, but phosphoric acid or / and phosphoric acid compound The reason for this is that it acts to increase the reactivity between the tetravalent vanadium compound and the plating film, and that a composite film of the tetravalent vanadium compound and phosphoric acid or / and a phosphoric acid compound is formed. . In addition, in a film in which a tetravalent vanadium compound and phosphoric acid or / and a phosphoric acid compound are added in combination, not only the above-described effect of improving the corrosion resistance is obtained, but also the dissolution resistance of the film is improved. Appearance quality (anti-coloring) and blackening resistance are improved, and Pef adhesion is also improved.

  The addition of the silane compound (C) has an effect of improving film adhesion and corrosion resistance. Among the silane compounds having an epoxy group or / and an amino group, examples of the silane compound having an epoxy group include 3-glycidoxypropyltrimethoxyxylene, 3-glycidoxypropyltriethoxyxylane, and 3-glycidoxy. Examples of the silane compound having an amino group include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and the like. The above can be used. It has been found that by polymerizing such a silane compound into an acrylic resin, the anticorrosion effect of the acrylic resin can be dramatically improved. On the other hand, when a silane compound having no epoxy group or amino group, for example, a silane compound having a methacryloxy group or an acryloxy group is polymerized to an acrylic resin, the film characteristics are adversely affected. Therefore, it is necessary to blend a silane compound having an epoxy group or / and an amino group.

The reason for the addition of organic resin is mainly improvement of workability and corrosion resistance, and by including organic resin in the film, it is possible to prevent the formation of sliding scratches with the mold in roll forming or press working Become. The type of resin is not particularly limited, and epoxy resin, urethane resin, acrylic resin, acrylic-ethylene copolymer, acrylic-styrene copolymer, alkyd resin, polyester resin, ethylene resin, fluorine resin, etc. However, from the viewpoint of corrosion resistance, it is preferable to use an organic polymer resin having one or more of OH group, COOH group, epoxy group and amide group. Examples of organic polymer resins having these functional groups include epoxy resins, polyhydroxy polyether resins, acrylic copolymer resins, ethylene-acrylic acid copolymer resins, alkyd resins, polybutadiene resins, phenol resins, and polyurethanes. Examples thereof include resins, polyamine resins, polyphenylene resins, and mixtures or addition polymers of two or more of these resins.
Water-dispersed organic resin D

  As epoxy resins, epoxy resins obtained by glycidyl etherification of bisphenol A, bisphenol F, novolak, etc., epoxy resins obtained by adding propylene oxide, ethylene oxide or polyalkylene glycol to bisphenol A, and aliphatic epoxy resins An alicyclic epoxy resin, a polyether epoxy resin, or the like can be used. These epoxy resins preferably have a number average molecular weight of 1500 or more, particularly when curing at low temperatures is required. In addition, the said epoxy resin can also be used individually or in mixture of a different kind. Moreover, it can also be set as a modified epoxy resin, and the resin which made various modifiers react with the epoxy group or hydroxyl group in the said epoxy resin is mentioned. For example, epoxy ester resin reacted with carboxyl group in drying oil fatty acid, epoxy acrylate resin modified with acrylic acid, methacrylic acid, etc., urethane modified epoxy resin reacted with isocyanate compound, urethane obtained by reacting epoxy compound with isocyanate compound An amine-added urethane-modified epoxy resin obtained by adding an alkanolamine to a modified epoxy resin can be used.

The polyhydroxy polyether resin is a polycondensation of a mononuclear or binuclear dihydric phenol or a mixed dihydric phenol of mononuclear and binuclear with an approximately equimolar amount of epihalohydrin in the presence of an alkali catalyst. It is a polymer obtained by making it. Representative examples of mononuclear dihydric phenols include resorcin, hydroquinone, and catechol. Typical examples of dinuclear phenols include bisphenol A. These may be used alone or in combination of two or more. it can.
Examples of the urethane resin include an oil-modified polyurethane resin, an alkyd polyurethane resin, a polyester polyurethane resin, a polyether urethane resin, and a polycarbonate polyurethane resin.
Examples of alkyd resins include oil-modified alkyd resins, rosin-modified alkyd resins, phenol-modified alkyd resins, styrenated alkyd resins, silicon-modified alkyd resins, acrylic-modified alkyd resins, oil-free alkyd resins, and high molecular weight oil-free alkyd resins. Can be mentioned.

  Examples of the acrylic resin include polyacrylic acid and its copolymer, polyacrylic acid ester and its copolymer, polymethacrylic acid and its copolymer, polymethacrylic acid ester and its copolymer, urethane-acrylic acid Copolymers (or urethane-modified acrylic resins), styrene-acrylic acid copolymers, and the like. Further, these resins are used as (meth) acrylic acid-2-hydroxyethyl, (meth) acrylic acid hydroxypropyl, acrylamide, N -A resin copolymerized with methylol acrylamide, diacetone acrylamide, glycidyl methacrylate, acrylonitrile, or a resin modified with another epoxy resin, urethane resin or the like may be used.

Examples of ethylene resins include ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, ethylene copolymers such as carboxyl-modified polyolefin resins, ethylene-unsaturated carboxylic acid copolymers, ethylene ionomers, and the like. Furthermore, resins obtained by modifying these resins with other alkyd resins, epoxy resins, phenol resins, or the like may be used.
Examples of fluororesins include fluoroolefin copolymers, which include, for example, alkyl vinyl ether, synchroalkyl vinyl ether, carboxylic acid-modified vinyl ester, hydroxyalkyl allyl ether, tetrafluoropropyl vinyl ether, and the like as monomers. There is a copolymer obtained by copolymerizing an olefin). When these fluororesins are used, excellent weather resistance and excellent hydrophobicity can be expected.

For the purpose of lowering the drying temperature of the resin, it is also possible to use a core / shell type water-dispersible resin made of different resin types or resins having different glass transition temperatures in the core part and the shell part of the resin particles. is there.
Said organic resin can be used 1 type or in mixture of 2 or more types.
Furthermore, in order to improve the corrosion resistance and workability of the organic film, it is particularly desirable to use a thermosetting resin. In this case, urea resin (butylated urea resin, etc.), melamine resin (butylated melamine resin), butyl A curing agent such as an amino resin such as fluorinated urea / melamine resin or benzoguanamine resin, a blocked isocyanate, an oxazoline compound, or a phenol resin can be blended.
In the present invention, the resin composition is not particularly limited, and can be selected according to necessary properties such as corrosion resistance, workability, adhesion to a bonded material such as a heat insulating material, and film costs. However, in these characteristics, it is preferable to apply a urethane resin, an acrylic resin, or a modified product containing these as a main component.

  The surface-treated film is mainly composed of the above components (A) to (D), but other appropriate components may be added for the purpose of further improving the corrosion resistance. For example, colloidal silica and its derivatives, phosphate rust preventives and composite compounds thereof, Zn, Mg, Co, Ni, Fe, Sr, Y, Nb, Ta, Ca, Ba based metal compounds, etc. Is possible. Moreover, you may add vanadium compounds other than Ta type compound, Nb type compound, and a tetravalent vanadium compound.

Next, the adhesion amount of the surface treatment film will be described. First, the adhesion amount of the organic resin (C) in the surface treatment film is set to 0.5 to 5 g / m ² . When the adhesion amount of the organic resin is less than 0.5 g / m ² , the corrosion resistance and workability are remarkably lowered. On the other hand, when organic resin is made to adhere exceeding 5 g / m < ² >, a film | membrane will adhere easily to the roll and metal mold | die in the case of roll forming or press work. Moreover, the more preferable range of the adhesion amount of organic resin (C) from the above viewpoint is 1.0-4.5 g / m < ² >, More desirably, it is 1.5-4.0 g / m < ² >.
Moreover, the adhesion amount of a vanadium compound (A) shall be 1-100 mg / m < ² > in conversion of the metal V. FIG. If the amount of vanadium compound deposited is less than 1 mg / m ² , the effect of improving corrosion resistance is not recognized. On the other hand, even if the amount exceeds 100 mg / m ² , the effect of improving corrosion resistance is saturated. There is a tendency to decrease. Moreover, the more preferable range of the adhesion amount in conversion of the metal V of a vanadium compound (A) from the above viewpoint is 3-50 mg / m < ² >, More desirably, it is 5-40 mg / m < ² >.

Further, adhesion of the phosphoric acid or / and phosphoric acid compound (B) is preferably set to 5 to 200 mg / ^{m 2} at PO ₄ terms. If the adhesion amount is less than 5 mg / m ² , the effect of improving the corrosion resistance and Pef adhesion is not sufficient, while if added excessively, the water resistance of the film is lowered and the film tends to be whitened by contact with water. However, since this whitening is greatly influenced by the physical properties of the resin, the addition amount can be selected from these viewpoints.
Furthermore, when using phosphates such as Zn, Ni, Mg, etc., it is necessary to dissolve in the treatment liquid, and if it is excessively large, the stability of the treatment liquid will be lowered, so it is necessary to keep it within an appropriate range. It is.

Next, the manufacturing method of the surface treatment material of this invention is demonstrated.
In the first production method of the present invention, a vanadium compound (A) having a tetravalent valence and phosphoric acid or / and a phosphoric acid-based compound on the surface of the plating film of the Al-Zn alloy-plated steel sheet as described above. (B), a silane compound (C) having an epoxy group or / and an amino group, and a treatment liquid mainly composed of a water-soluble organic resin or / and an organic resin (D) made of a water-dispersible organic resin (above-mentioned) After applying the component (A) to (D), a treatment solution in which water is dissolved or / and dispersed), it is dried without being washed with water.
In the second production method of the present invention, the vanadium compound (A) having a tetravalent valence and phosphoric acid or / and phosphorus are first formed on the surface of the plating film of the Al—Zn alloy-plated steel sheet as described above. After applying the treatment liquid (a) containing the acid compound (B) as a main component (treatment liquid in which the above components (A) and (B) are dissolved or / and dispersed) in water, drying is performed without washing. Further, a treatment liquid (b) containing an organic resin (D) composed of a water-soluble organic resin and / or a water-dispersible organic resin as a main component (the organic resin (D) is dissolved or / and dispersed in water) And then dried without washing with water. In that case, a silane compound (C) is mix | blended with processing liquid (I) or / and (B).

Of these two manufacturing methods, the second manufacturing method tends to be superior from the viewpoint of corrosion resistance, but the first manufacturing method is advantageous from the viewpoint of equipment load. However, in either case, the required level of quality can be obtained.
Moreover, in the said 2nd manufacturing method, 1 or more types of a vanadium compound (A) and phosphoric acid or / and a phosphoric acid type compound (B) in the process liquid which has organic resin (D) as a main component. It is also possible to add.
A processing liquid is adjusted by adding each component (A)-(D) with respect to water. The kind of each component (A)-(D), the form of the compound when adding each component, and the addition method are as described above. Moreover, in addition to the said components (A)-(D), the additive component described previously can be added to a process liquid as needed.

The application method of the treatment liquid is arbitrary, for example, spray + roll squeezing, roll coater, and the drying method after application is arbitrary, for example, a hot air method, an induction heating method, an electric furnace method, and the like.
The drying temperature of the treatment liquid is preferably about 60 to 250 ° C. When the drying temperature is less than 60 ° C., the film formation is insufficient and the film is inferior in corrosion resistance and the like. On the other hand, even if it is dried at a plate temperature exceeding 250 ° C., the effect of improving the quality such as corrosion resistance cannot be obtained, and it may be lowered. This is presumably because the film is damaged by heat because the heat resistance limit of the organic resin is exceeded.

[Example 1]
The treatment liquid to which the metal compound and organic resin and phosphoric acid (orthophosphoric acid) shown in Tables 1 and 2 are added is applied to 55% Al—Zn alloy-plated steel sheet and electrogalvanized steel sheet, and dried at a plate temperature of 120 ° C. This was used as a test material. As the silane compound in the treatment liquid, 3-glycidoxypropyltrimethoxysilane was used.

About the obtained test material, corrosion resistance, water resistance, and workability were evaluated on the following test conditions (however, the test material of an electrogalvanized steel sheet is only corrosion resistance).
(1) Corrosion resistance The salt spray test (SST: JIS Z 2371) was conducted for 240 hours for the high Al-Zn alloy-plated steel sheet and 48 hours for the electro-galvanized steel sheet, respectively. The occurrence status of the was evaluated according to the following criteria.
○: White rust (black rust) generation area rate of less than 10% △: White rust (black rust) generation area rate of 10% or more, less than 50% ×: White rust (black rust) generation area rate of 50% or more

(2) Water resistance The water resistance evaluation test was performed only on the specimens of the high Al—Zn alloy-plated steel sheets that showed “◯” or “Δ” in the corrosion resistance test.
The water resistance was evaluated by visual observation according to the following criteria after standing for 1 week in an environment of 50 ° C. and> 98% RH with the treated surfaces stacked together.
○: No abnormality △: Light coloration ×: Significant coloration, blackening, or film peeling

(3) Workability The workability evaluation test was performed only on the specimens of the high Al—Zn alloy-plated steel sheets that were evaluated as “◯” and “Δ” in the corrosion resistance test.
Using a draw bead tester, a bead with a tip of 5 mmR was pressed against the surface of the test material with a width of 30 mm with a load of 150 kgf, and a pull-out test was performed.
○: No abnormality △: The surface of the test material is blackened, or the appearance of the test material is good, but there is a significant deposit on the bead.

Tables 1 and 2 show the coating composition of each test material, and Tables 3 and 4 show the results of the above tests.
No. 1-No. No. 16 is a comparison of the anticorrosive effect of the metal compound added to the surface treatment film. No. 16 in which a tetravalent vanadium compound was added to the surface treatment film of the high Al—Zn alloy-plated steel sheet. Only 7 (invention example) shows excellent corrosion resistance. Moreover, it turns out that the effect by such a tetravalent vanadium compound is an effect peculiar to a high Al-Zn type alloy plating steel plate, and is not acquired with a galvanization steel plate.

No. 17-No. No. 19 is an investigation of the effect of the coating amount. No. 19 having a coating amount less than the range of the present invention. No. 17 (Comparative Example) is inferior in corrosion resistance, while No. 17 in which the coating amount exceeds the range of the present invention. 19 (Comparative Example) is inferior in water resistance and workability. No. 20, no. No. 21 is obtained by changing the type of organic resin, and shows excellent characteristics even in acrylic and urethane resins.
No. No. 22 (invention example) 1-No. No. 21 is different in production conditions, and after applying and drying a treatment liquid containing a tetravalent vanadium compound and phosphoric acid, a surface treatment film is formed by applying and drying a treatment liquid containing an organic resin. No. Excellent characteristics similar to those of No. 7 (Invention Example) are obtained.

[Example 2]
The treatment liquid to which the metal compound and phosphoric acid or phosphoric acid compound shown in Table 5 and the organic resin (a) of Example 1 were added was applied to a 55% Al—Zn alloy-plated steel sheet and dried at a plate temperature of 120 ° C. This was used as a test material. The corrosion resistance, pef adhesion, and workability of each test material were evaluated by the same method and standard as in Example 1.
Table 5 shows the coating composition of each test material, and Table 6 shows the results of the above test.
No. No. 1 (Comparative Example) is an example in which phosphoric acid is not added to the surface treatment film, and the corrosion resistance and water resistance are inferior.
No. 2-No. No. 5 (all invention examples) investigated the effect of the type of phosphoric acid or phosphoric acid compound added to the surface treatment film, and was excellent in all of orthophosphoric acid, phosphoric acid Mg and Zn phosphate. Is obtained.
No. No. 6 (invention example) is an example using a reduction product of a pentavalent vanadium compound as a tetravalent vanadium compound. 2-No. The same excellent characteristics as the vanadium sulfate oxide used in No. 5 were obtained.

[Example 3]
A test liquid was prepared by applying a treatment liquid to which a metal compound and an organic resin and phosphoric acid (orthophosphoric acid) shown in Table 7 were added to a 55% Al—Zn alloy-plated steel sheet and drying at a plate temperature of 120 ° C. . The corrosion resistance, water resistance, and processability of these samples were evaluated according to the same standards as in Example 1.
In addition, 1 type chosen from the following AF was used as a silane compound (i).
A: 3-methacryloxypropyltrimethoxysilane B: 3-acryloxypropyltrimethoxysilane C: 3-glycidoxypropyltrimethoxysilane D: 3-glycidoxypropyltriethoxysilane E: 3-aminopropyltrimethoxy Silane F: 3-Aminopropyltriethoxysilane

  No. No. 1 is an example in which no silane compound is added, and as a result, the film is inferior in corrosion resistance, water resistance and workability. No. Nos. 2 to 7 are examples in which a silane compound containing no epoxy group or amino group is applied, but a decrease in corrosion resistance is observed by addition. No. Nos. 8 to 10 are silane compounds containing an epoxy group; Although 11 to 17 are examples in which a silane compound containing an amino group is applied, the effect is recognized although there is a difference in effect depending on the addition amount, and a remarkable effect is recognized when an appropriate amount is added.

Claims (3)

A vanadium compound (A) having a tetravalent valence and phosphoric acid or / on the surface of the plated film of an Al-Zn based alloy plated steel sheet having an Al-Zn based alloy plated film containing 25 to 75% by mass of Al. And a phosphoric acid compound (B), a silane compound (C) having an epoxy group or / and an amino group, and an organic resin (D) composed of a water-soluble organic resin and / or a water-dispersible organic resin. The vanadium compound (A) comprises a vanadium sulfate oxide or vanadate reduction product, and the amount of the vanadium compound (A) deposited in terms of metal V is 1 to 100 mg / m ² , and the organic resin (D) is deposited. A chromate-free surface-treated Al—Zn alloy-plated steel sheet excellent in corrosion resistance, characterized by having a surface-treated film having an amount of 0.5 to 5 g / m ² . A vanadium compound (A) having a tetravalent valence and phosphoric acid or / on the surface of the plated film of an Al-Zn based alloy plated steel sheet having an Al-Zn based alloy plated film containing 25 to 75% by mass of Al. and phosphoric acid-based compound (B), and silane compound having an epoxy group and / or amino group (C), and a main component and an organic resin (D) comprising a water-soluble organic resin and / or water-dispersible organic resin Chromate-free surface-treated Al-Zn system with excellent corrosion resistance, characterized in that the vanadium compound (A) is coated with a treatment solution comprising a vanadium sulfate oxide or vanadate reduction product and then dried without washing. Manufacturing method of alloy-plated steel sheet. A vanadium compound (A) having a valence of 4 and phosphoric acid or / and on the surface of the plating film of an Al-Zn alloy-plated steel sheet having an Al-Zn-based alloy plating film containing 25 to 75 mass% of Al. After applying the treatment liquid ( ii) comprising the phosphoric acid compound (B) as a main component and the vanadium compound (A) comprising a vanadium sulfate oxide or a vanadic acid reduction product, drying without washing with water, After applying a treatment liquid (b) mainly composed of an organic resin (D) composed of a water-soluble organic resin and / or a water-dispersible organic resin on the top, the treatment liquid (ii) is dried without washing with water. Or / and the treatment liquid (b) contains a silane compound (C) having an epoxy group or / and an amino group, and is a chromate-free surface-treated Al—Zn alloy alloy having excellent corrosion resistance. Method of manufacturing a steel plate.