KR20040044944A - Precoated metal sheet with excellent press formability and process for producing the same - Google Patents

Abstract

A pre-coated metal sheet having excellent press formability and a method for producing the same, which has, on one or both surfaces thereof, a solidified coating layer containing at least one of a silane binder, fine silica and tannin and tannic acid as solids; A pre-coated metal sheet having excellent press formability and a method for producing the same, including a metal sheet further comprising a coating layer containing 1 to 140 parts by mass of an aluminum phosphate pigment per 100 parts by mass of a resin solid content. The chemical conversion treatment layer further contains a polyester resin and the coating layer further contains a rust preventive pigment. The aluminum phosphate pigment is preferably tripolyphosphoric aluminum dihydrogen phosphate, and the rust preventive pigment is preferably calcium ion exchangeable silica.

Description

Pre-coated metal sheet having excellent press formability and manufacturing method thereof {PRECOATED METAL SHEET WITH EXCELLENT PRESS FORMABILITY AND PROCESS FOR PRODUCING THE SAME}

Instead of post-coated products obtained by conventional post-processing resin coatings used in home appliances, building materials and automobiles, precoated metals coated with colored coatings are used. This pre-coated metal sheet is obtained by forming a layer of a resin coating composition on a metal sheet subjected to pretreatment for metal. After covering with the resin coating composition, the pre-coated metal sheet is cut and press molded and used. Therefore, the pre-coated metal sheet has problems of corrosion resistance on the cut end face portion where the metal is not covered with the resin coating layer and exposed, and peeling of the resin coating during press molding. However, if chromate treatment is applied as a pretreatment for metal and a resin coating containing hexavalent chromium-based rust preventive pigment is used, this problem is solved. Such metal sheets are currently used for general use.

However, hexavalent chromium which may be dissolved from the hexavalent chromium-based rust-preventive pigment-containing resin coating layer and chromate treated film has a problem in terms of environment. Therefore, in recent years, the demand for bichromate conversion treatment and bichromate resin coating material which does not contain hexavalent chromium is increasing. Japanese Patent Laid-Open No. 2001-89868 discloses a technique for providing a pre-coated metal sheet having excellent adhesion and high corrosion resistance of a processed portion by using a chemical conversion treatment containing tannin, tannic acid, silane binder and fine silica instead of chromate treatment. Is disclosed. On the other hand, in Japanese Patent Application Laid-Open No. 9-12931, by using polyester-based and epoxy-based coating compositions in which phosphoric acid-based rust preventive pigments and ion-exchangeable silica-based rust preventive pigments are used in combination instead of hexavalent chromium-based rust preventive pigments, A technique is disclosed for providing a pre-coated metal sheet having good corrosion resistance of the cut end face portion.

The chemical conversion treatment technique disclosed in Japanese Patent Laid-Open No. 2001-89868 ensures excellent adhesion of the machined portion in the Erichsen test or T-bending test, but the chromate treatment is performed when press molding represented by deep drawing molding is performed. Compared to the pre-coated metal sheet implemented, the coating has the problem of being scratched and easily peeled off by the mold. On the other hand, the technique disclosed in Japanese Patent Application Laid-open No. Hei 9-12931 uses zinc phosphate for chemical conversion treatment, and the adhesion of the coating of the processed portion is insufficient and press molding is performed as compared with the all-coated metal sheet subjected to chromate treatment. Has a problem that the coating is scratched by the mold and easily peeled off.

It is an object of the present invention to solve this problem of the prior art and to provide a pre-coated metal sheet and a method for producing the same, which have excellent corrosion resistance even when not containing hexavalent chromium, and also have excellent press formability.

The present invention can be used in home appliances, building materials, civil engineering, machinery, automobiles, furniture, or containers without using hexavalent chromium having a problem in terms of the environment, and can exhibit the anti-rust effect and coating adhesion during press molding. The present invention relates to a surface treated metal material having excellent press formability and corrosion resistance.

1 shows a chemical conversion coating layer 2 comprising at least one of tannin or tannic acid, a silane binder and fine silica on a surface of a metal sheet 1, a resin coating layer 3 containing an aluminum phosphate pigment, Schematic cross section of a press-formed pre-coated metal sheet, in which an optional top coat layer 4 is formed, and layers 2 and 4 may be formed on both surfaces of the metal sheet.

The present inventors found that when a chemical conversion coating layer containing silane binder, fine silica and at least one of tannin and tannic acid is formed and a resin coating layer containing an aluminum phosphate pigment is formed thereon, the obtained composite coating film It has been found that it can have very good press formability as well as this excellent corrosion resistance. The present invention has been accomplished based on these findings. The gist of the present invention is as follows.

(1) On one surface or both surfaces, as a solid content, it has a chemical conversion treatment layer which simultaneously contains a silane binder, fine silica, and at least one of tannin and tannic acid, and thereafter, aluminum phosphate pigment 1 to 100 parts by mass of resin solid content thereon. A pre-coated metal sheet having excellent press formability, including a metal sheet further having a resin coating layer containing 140 parts by mass.

(2) The said chemical conversion coating layer is the all-coated metal sheet which has the outstanding press formability as described in said (1) which further contains a polyester resin as solid content.

(3) The all-coated metal sheet having excellent press formability as described in (1) or (2), wherein the aluminum phosphate pigment contained in the resin coating layer is tripolyphosphoric aluminum dihydrogen.

(4) The resin coating layer further contains an rust preventive pigment, and the total content of the rust preventive pigment and the aluminum phosphate pigment is as described in any one of the above (1) to (3), which is 140 parts by mass or less per 100 parts by mass of the resin solids. Pre-coated metal sheet having the same excellent press formability.

(5) The pre-coated metal sheet having excellent press formability as described in (4) above, wherein the rust preventive pigment contained in the resin coating layer is calcium ion exchangeable silica.

(6) The all-coated metal sheet having excellent press formability as described in any one of (1) to (5), wherein the metal sheet is a metal sheet having a plating layer on one surface or both surfaces thereof.

(7) On one or both surfaces of the metal sheet, a treatment liquid containing silane binder, fine silica and at least one of tannin and tannic acid at the same time is coated, and the treatment liquid is dried to form a chemical conversion coating layer, and also chemical A method for producing a pre-coated metal sheet having excellent press formability, comprising coating a resin coating composition containing 1 to 140 parts by mass of an aluminum phosphate pigment per 100 parts by mass of a resin solid content on the treated coating layer, and drying and curing the coating material.

(8) The method for producing a pre-coated metal sheet having excellent press formability as described in (7), wherein the treatment liquid further contains a polyester resin.

(9) The coating composition further contains an rust-preventive pigment, and the total content of the rust-preventive pigment and the aluminum phosphate-based pigment is excellent press as described in the above (7) or (8), which is 140 parts by mass or less per 100 parts by mass of the resin solids. A method of manufacturing a pre-coated metal sheet having formability.

(10) A press-formed pre-coated metal product comprising a press-formed pre-coated metal sheet, wherein the press-formed pre-coated metal sheet is described in (1) to (9) above.

The present invention forms, on a surface or both surfaces of a metal sheet or a plated metal sheet, a solidification treatment coating layer containing at least one of a silane binder, fine silica, and tannin and tannic acid simultaneously, on which an aluminum phosphate pigment 1 It can be achieved by further forming a resin coating layer containing from 140 parts by mass. The aluminum phosphate pigment is preferably tripolyphosphoric aluminum dihydrogen because the coating has greater scratch resistance during press molding. Moreover, it is preferable that the chemical conversion coating layer used for the all-coated metal sheet of this invention further contains a polyester resin as solid content, since the adhesiveness of a coating improves and a coating has more scratch resistance during press molding.

It is preferable that the resin coating layer formed on the all-coated metal sheet of this invention contains an antirust pigment in addition to the aluminum phosphate pigment because the corrosion resistance of an all-coated metal sheet improves. The amount of these pigments added is preferably 140 parts by mass or less per 100 parts by mass of the resin solid content as the total content of the aluminum phosphate pigment and the rust preventive pigment. Moreover, since this corrosion resistance pigment | dye improves further, it is preferable that it is calcium ion exchangeable silica.

The chemical conversion coating layer formed on the pre-coated metal sheet of the present invention is coated with such a coating liquid additionally containing a coating liquid or a polyester resin simultaneously containing a silane binder, fine silica and at least one of tannin and tannic acid, and coating the coated coating liquid. It is preferably formed by drying, whereby the pre-coated metal sheet of the present invention can be produced more efficiently. Moreover, the resin coating layer formed on the pre-coated metal sheet of the present invention is formed by coating a resin coating composition containing an aluminum phosphate pigment or a resin coating containing both an aluminum phosphate pigment and an rust preventive pigment, and drying and curing the resin coating composition. It is preferable that the pre-coated metal sheet of the present invention can be produced more efficiently.

As a result of various studies on non-chromate pre-coated metal sheets in which the coated layer is rarely scratched by the mold during press molding, we have found that a chemical conversion coating layer containing tannin and / or tannic acid, silane binder and particulate silica simultaneously It has been found that when a coating layer formed on a metal sheet or a plated metal sheet and containing thereon an aluminum pigment is formed, the phenomenon that the coating is peeled off by scratching by the mold during press molding is significantly prevented. The phenomenon that the coating is scratched and peeled off by the mold during press molding is considered to occur because the coating of the pre-coated metal sheet is scratched by the mold under high load, whereby the shear force acts on the coating. Therefore, the following two methods can be considered to solve this problem. The first method is to increase the adhesion strength between the coating and the metal. The second method is to make shear forces acting on the coating difficult to transfer to the coating release surface, which is the interface between the coating and the original metal sheet. It is not clear why the coating of the pre-coated metal sheet of the present invention is scratch resistant by a mold during press molding, but a chemical conversion coating layer containing tannin and / or tannic acid, a silane binder and fine silica simultaneously and having excellent adhesion Combined with a resin coating layer containing an aluminum phosphate pigment, the adhesion of the coating is significantly improved by the synergistic effect and the inherent mechanical properties of the aluminum phosphate pigment cause the shear force generated in the coating during press molding to be applied to the coating and metal sheet. It is considered to be because the transfer to the interface between them is prevented easily.

The metal sheet used for the all-coated metal sheet of this invention is a cold rolled sheet steel, a hot rolled sheet steel, a hot dip galvanized steel sheet, an electrogalvanized steel sheet, a molten alloy galvanized steel sheet, an aluminum plated steel sheet, an aluminum- zinc alloy plated steel sheet, aluminum-magnesium It may also be a generally known metal sheet or a plated metal sheet such as a zinc plated steel sheet, an aluminum-magnesium-silicon-zinc plated steel sheet, a stainless steel sheet and an aluminum sheet. These metal sheets may be subjected to conventional treatments such as hot water washing and alkali degreasing prior to chemical conversion.

The chemical conversion coating layer formed on the pre-coated metal sheet of the present invention is characterized by containing tannin and / or tannic acid, a silane binder and fine silica.

Tannin or tannic acid to be used may be hydrolyzable tannin, condensed tannin or a partial decomposition product thereof. Tannins and tannic acids are not particularly limited and include, for example, hamamelitannin, Chinese gallotanin, nutgalls-tannin, myrobalan tannin, divi-ditanin divi tannin), algarobillatannin, valonia tannin and catechin. When "tannic acid: AL" (Fuji Chemical Co., Ltd.) is used, the coating is particularly improved in the adhesion of the processed portion. The addition amount of at least one of tannin and tannic acid is not particularly defined, but it is preferable that their content in the chemical conversion treatment liquid to be coated on the metal sheet to form a coating layer is 2 to 80 g / l. If the addition amount of at least one of tannin and tannic acid is less than 2 g / l, the rust preventing effect or coating adhesion may not be guaranteed, whereas if it exceeds 80 g / l, the rust preventing effect or coating adhesion is rather deteriorated or tannin or tannic acid is It may not be dissolved in the aqueous solution.

As an example of a silane binder that can be used, -(2-aminoethyl) aminopropyltrimethoxysilane, -2 (2-aminoethyl) aminopropylmethyldimethoxysilane, -(2-aminoethyl) aminopropyltriethoxysilane, -(2-aminoethyl) aminopropylmethyldiethoxysilane, -(2-aminoethyl) aminopropylmethyldimethoxysilane, Methacryloxypropyltrimethoxysilane, Methacryloxypropylmethyldimethoxysilane, Methacryloxypropyltriethoxysilane, -Methacryloxypropylmethyldiethoxysilane, N-β- (N-vinylbenzylaminoethyl)- -Aminopropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl)- -Aminopropylmethyldimethoxysilane, N-β- (N-vinylbenzylaminoethyl)- -Aminopropyltriethoxysilane, N-β- (N-vinylbenzylaminoethyl)- Aminopropylmethyldiethoxysilane, Glycidoxy propyltrimethoxysilane, Glycidoxypropylmethyldimethoxysilane, Glycidoxypropyltriethoxysilane, Glycidoxypropylmethyldiethoxysilane, Mercaptopropyltrimethoxysilane, Mercaptopropylmethyldimethoxysilane, Mercaptopropyltriethoxysilane, Mercaptopropylmethyldiethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, vinyltriacetoxysilane, Chloropropyltrimethoxysilane, Chloropropylmethyldimethoxysilane, Chloropropyltriethoxysilane, Chloropropylmethyldiethoxysilane, hexamethyldisilazane, -Anilinopropyltrimethoxysilane, -Anilinopropylmethyldimethoxysilane, -Anilinopropyltriethoxysilane, -Anilinopropylmethyldiethoxysilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, octadecyldimethyl [3- (triethoxysilyl) propyl] ammonium chloride, Octadecyldimethyl [3- (methyldiethoxysilyl) propyl] ammonium chloride, octadecyldimethyl [3- (triethoxysilyl) propyl] ammonium chloride, octadecyldimethyl [3- (methyldiethoxysilyl) propyl] ammonium Chloride, Chloropropylmethyldimethoxysilane, Mercaptopropylmethyldimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane and trimethylchlorosilane. In particular, having a group of glycidyl ethers Glycidoxypropyltrimethoxysilane or When glycidoxypropyltriethoxysilane is used, the coating improves the adhesion of the processed part. Moreover, when a triethoxy type silane binder is used, the surface treatment agent can improve the storage stability. This is considered to be because triethoxysilane is relatively stable in aqueous solution and the polymerization proceeds at a relatively low speed.

The amount of the silane binder added is not specifically defined, but it is preferable that the content in the chemical conversion treatment liquid to be coated on the metal sheet to form the chemical conversion coating layer is 2 to 80 g / l. If the content is less than 2 g / l, the adhesion of the coating sufficiently high during processing may not be obtained and the corrosion resistance may be insufficient, whereas if it exceeds 80 g / l, the coating adhesion may be rather reduced.

Fine silica for use in the present invention is a generic term for silica that has a fine particle size and can therefore stably maintain a water dispersion state when dispersed in water. Examples of particulate silicas that may be used include "Snowtex N", "Snowtex C", "Snowtex UP", "Snowtex PS" (all Nissan Chemical Industries, Ltd.) and "Adelite AT" Commercially available silica gel such as -20Q "(manufactured by Asahi Denka Kogyo Co., Ltd.) and powdered silica such as" Aerosil # 300 "(manufactured by Nippon Aerosil). The fine silica may be appropriately selected depending on the required performance. If fine silica is used that can stably disperse even above 4 pH, such as "Snowtex C", the surface treatment agent can improve storage stability. This is considered to occur because the pH of the chemical solution can be adjusted to 4 or higher and thus the reaction of the silane binder showing high reactivity at low pH can be suppressed.

The amount of fine silica added is also not specifically defined, but it is preferable that the content in the chemical conversion treatment liquid to be coated on the metal sheet to form the chemical conversion treatment film is 1 to 40 g / l. If the content is less than 1 g / l, the coating may have poor processing part adhesion, whereas if it exceeds 40 g / l, the effect of processing part adhesion and corrosion resistance is saturated and uneconomical.

It is preferable that a chemical conversion treatment coating layer further contains polyester resin as solid content, because work adhesiveness improves further. The content of the polyester resin is also not particularly defined, but if the content in the chemical conversion treatment liquid to be formed on the metal sheet to form the chemical conversion coating layer is 1 to 60 g / l, the processed part adhesion is further improved. If the content is less than 1 g / l, the effect by the addition of the resin is not obtained, while if it exceeds 60 g / l, the processed part adhesion of the coating may be rather reduced. Examples of polyester resins that can be used include "FINETEX ES-650", "Finetex ES-611", "Finetex ES-670", and "Finetex ES-675" (all from Dainipek Ink, Inc.). High school), "VILONAL MD-1200", "Bironal MD-1220", "Bironal MD-1250", "Bironal MD-1100", "Bironal MD-1330" And "Vironal MD-1930" (both manufactured by Toyobosei Co., Ltd.).

Acid, alkali, or the like may be added to the chemical conversion treatment liquid coated to form the chemical conversion treatment layer of the present invention in order to adjust the pH within a range that does not impair performance.

The chemical conversion coating layer is preferably formed on the metal sheet by coating the chemical conversion agent described above on the metal sheet and baking or heating / drying the chemical conversion agent. It is preferable that baking temperature is 50-250 degreeC. If the baking temperature is less than 50 ° C., the moisture evaporates at a low rate so that sufficiently good film formation properties cannot be obtained, resulting in insufficient rust preventive properties, whereas if it exceeds 250 ° C., the alkyl of tannin or tannic acid or silane binder as organic matter The part causes denaturation such as thermal decomposition and the adhesion or the corrosion resistance is lowered. The baking temperature is more preferably 70 to 160 ° C. In hot air drying, drying for 1 second to 5 minutes is preferable because the production efficiency is improved.

The coating method of the chemical conversion treatment liquid is not particularly limited and generally known coating methods such as roll coating, ringer roll coating, air spraying, airless spraying or dipping may be employed. It may be. The chemical conversion treatment liquid is preferably coated by a general continuous coating line complete with these coating apparatuses, called coil coating line or sheet coating line, since the coating operation can be performed with good efficiency and mass production can be achieved. Do.

It is preferable that the quantity of the chemical conversion treatment film layer formed is 10-500 mg / m <^2> as solid content. If the amount formed is less than 10 mg / m ² , sufficiently high machined part adhesion cannot be ensured, while if it exceeds 500 mg / m ² , the machined part adhesiveness is rather deteriorated.

In the pre-coated metal sheet of the present invention, the resin for the coating layer to be formed on the chemical conversion coating layer may be in any form, such as aqueous, solvent type, powder type and the like. In the type of resin, generally known resins such as polyacrylic resins, polyolefin resins, polyurethane resins, epoxy resins, polyester resins, polybutyral resins and melamine resins can be used by themselves or in combination. It may be.

The resin coating layer of the all-coated metal sheet of this invention should contain 1-140 mass parts of aluminum phosphate pigments per 100 mass parts of resin solid content. If the amount of the aluminum phosphate pigment added is less than 1 part by mass, there is no scratch resistance effect of the coating during press molding and this is inappropriate. As the amount of the aluminum phosphate pigment added increases, the scratch resistance effect of the coating is advantageously increased during press molding, but when the amount added exceeds 140 parts by mass, workability as a pre-coated metal sheet is greatly deteriorated, which is inappropriate. .

Examples of aluminum phosphate-based pigments that can be used include generally known pigments such as aluminum tripolyphosphate dihydrogen and aluminum metaphosphate. Of these, tripolyphosphoric aluminum dihydrogen is readily available and preferred. Examples of tripolyphosphoric aluminum dihydrogen that may be used include commercially available products such as "K-white" manufactured by Daika Corporation.

In the coating layer of the all-coated metal sheet of this invention, it is preferable that the antirust pigment which can exhibit an antirust effect is added in addition to an aluminum phosphate pigment in order to improve corrosion resistance. As the amount of the rust preventive pigment added increases, the effect exerted advantageously increases, but the total content of the aluminum phosphate pigment and the rust preventive pigment is preferably 140 parts by mass or less per 100 parts by mass of the resin solids. When the total content of the aluminum phosphate pigment and the rust preventive pigment added exceeds 140 parts by mass, problems such as deterioration of workability, for example, occur when the pre-coated metal sheet is bent, are undesirable.

The rust preventive pigment added to the resin coating layer of the all-coated metal sheet of the present invention may be a generally known rust preventive pigment. Examples thereof include (1) phosphate antirust pigments such as zinc phosphate and iron phosphate, (2) molybdate anticorrosive pigments such as calcium molybdate, aluminum molybdate and barium molybdate, and (3) vanadium antirust such as vanadium oxide Pigments, (4) strontium chromate, zinc chromate, calcium chromate, calcium chromate, potassium chromate and barium chromate and (5) moisture Particulate silicas such as acid silica, fused silica and calcium ion exchange silica. However, the chromate rust preventive pigment of (4) is preferably not used because it has problems in terms of environment. Among the silica pigments of (5), calcium ion exchangeable silica is preferable because it is harmless in terms of environment, has an excellent antirust effect and exhibits a higher antirust effect when added as an antirust pigment. Examples of calcium ion exchangeable silicas that may be used include "Shieldex" from Grace. These rust preventive pigments may be added as a combination of a plurality of pigments.

In the coating layer of the pre-coated metal sheet of the present invention, a known pigment generally called an extender pigment or a coloring pigment for coloring may be used and added in combination with these aluminum phosphate pigments and rust preventive pigments. A sieving pigment is a generic term for pigments added to enhance the various performances that a coating requires such as masking properties after coating or brittleness of the coating. Examples of these include talc, which may serve as a filling or matting of the coating, titanium white (titanium oxide) to improve the hiding properties of the coating, and to polish the coating or to improve the scratchability of the coating. Silica to be included. When this extender pigment is added, the above-mentioned various performances are advantageously improved. Examples of colored pigments that may be used include titanium oxide (TiO ₂ ), zinc oxide (ZnO), zirconium oxide (ZrO ₂ ), calcium carbonate (CaCO ₃ ), barium sulfate (BaSO ₄ ), alumina (Al ₂ O ₃ ), Generally known colored pigments including inorganic pigments such as kaolin clay, carbon black and iron oxides (Fe ₂ O ₃ , Fe ₃ O ₄ ) and organic pigments. Since a plurality of extender pigments and colored pigments having various effects can exert respective effects, they are preferably used in combination. In the case where the extender pigment and the colored pigment are added, the amount of addition of all the pigments as the sum total of the aluminum phosphate pigment, the rust preventive pigment, the extender pigment and the color pigment is suitably 140 parts by mass or less per 100 parts by mass of the resin solids in the coating composition. When the addition amount of all the pigments exceeds 140 parts by mass, problems may arise, for example, when workability is greatly degraded when the pre-coated metal sheet is bent.

In the pre-coated metal sheet of the present invention, the layer thickness of the coating containing the aluminum phosphate pigment is not specifically defined, but the layer thickness should be appropriately selected in some cases because various performances of the coating vary with the layer thickness.

In the pre-coated metal sheet of the present invention, the resin coating layer containing the aluminum phosphate pigment is prepared in advance for the coating composition containing the pigment in the amount specified in the present invention based on the resin solid content, and the coating composition is coated, dried and cured. It is preferable to form by this, and manufacturing efficiency improves further by this. The coating composition may be used in any form of solvent type coating composition, aqueous coating composition, melt coating composition, powder coating composition, electrodeposition coating composition, UV curable coating composition and electron beam curable coating composition. The coating composition is, for example, roll coating, curtain flow coating, roller curtain coating, die coating, air spray, airless spray, electrodeposition coating, powder coating, dipping, bar coating or brush coating It may be coated by a generally known coating method such as. The coating composition is a general continuous coating line called coil coating line or sheet coating line, complete with roll coating, curtain flow coating or roller curtain coating, since the coating operation can be carried out with good efficiency and mass production can be obtained. It is preferred to be coated by. The coating composition may be dried, baked and cured by commonly known dry curing methods such as hot air ovens, direct ovens, far infrared ovens or induction heating ovens. If the coating composition is an ultraviolet curable coating composition, a generally known ultraviolet irradiation device may be used, and in the case of an electron beam curable coating composition, a generally known electron beam irradiation device may be used.

In the pre-coated metal sheet of the present invention, a phase coating layer may be further provided on the resin coating layer containing the aluminum phosphate pigment. By providing an upper coating layer, the coating appearance, color tone appearance, design appearance and other coating performance of the pre-coated metal sheet are advantageously further improved. The phase coating layer can be formed by coating a generally known phase coating composition and drying, baking and curing the coating composition. Examples of generally known phase coating compositions include polyester based coating compositions, epoxy based coating compositions, urethane based coating compositions, acrylic based coating compositions and melamine based coating compositions. The phase coating composition may be used in any form of solvent type coating composition, aqueous coating composition, powder coating composition, electrodeposition coating composition, UV curable coating composition and electron beam curable coating composition. The phase coating composition is titanium oxide (TiO ₂ ), zinc oxide (ZnO), zirconium oxide (ZrO ₂ ), calcium carbonate (CaCO ₃ ), barium sulfate (BaSO ₄ ), alumina (Al ₂ O ₃ ), kaolin clay, carbon It may also contain generally known color pigments or extender pigments such as black, iron oxides (Fe ₂ O ₃ , Fe ₃ O ₄ ), talc and silica. As the phase coating composition, orange peel tone coating composition, crepe tone coating composition, hammer tone coating composition, matted tone coating composition, metallic tone coating composition, pearl tone Generally known design coating compositions such as coating compositions or texture coating compositions may also be used. The top coating composition may be coated by generally known coating methods such as roll coating, curtain flow coating, roller curtain coating, die coating, air spray, airless spray, electrodeposition coating, powder coating, dipping, bar coating or brush coating. have. The phase coating material is a general continuous coating line called coil coating line or sheet coating line, complete with roll coating, curtain flow coating and roller curtain coating, since the coating operation can be performed with good efficiency and mass production can be obtained. It is preferred to be coated by. The phase coating composition may be dried, baked and cured by generally known drying and baking methods such as hot air ovens, direct ovens, far infrared ovens or induction heating ovens. If the phase coating composition is an ultraviolet curable coating composition, a generally known ultraviolet irradiation device may be used, and in the case of an electron beam curable coating composition, a generally known electron beam irradiation device may be used.

Yes

The material used for experiment is demonstrated below.

1. metal sheet

The following metal sheets were used as test materials in the experiment.

Hot Dip Galvanized Steel Sheet (GI)

Sheet thickness: 0.6 mm, amount of zinc deposited: 60 g / m ² per day (both surfaces plated).

Electro Galvanized Steel Sheet (EG)

Sheet thickness: 0.6 mm, amount of zinc deposited: 20 g / m ² per surface (both surfaces are plated).

55% alloy aluminum galvanized steel (GL)

Sheet thickness: 0.6 mm, adhesion amount in terms of zinc: 90 g / m ² per surface (both surfaces are plated).

Zn-11% Aluminum-3% Magnesium-0.2% Silicon Plated Steel Sheet (SD)

Thickness of sheet: 0.6 mm, adhesion amount in terms of zinc: 60 g / m ² per surface (both surfaces are plated).

Cold Rolled Steel Sheets (CR)

Sheet thickness: 0.6 mm.

2. Chemical treatment liquid

The following solutions were prepared as chemical conversion treatment liquids used as test materials in the experiment.

Chemical treatment solution (A) :

An aqueous solution containing 20 g / l tannic acid, 40 g / l silane binder and 20 g / l fine silica was prepared and used as a pretreatment for metals. The tannic acid used is Fujigakug Kogyo Co., Ltd. "Tanic acid AL", and the silane binder -Glycidoxypropyltrimethoxysilane, and fine silica is Nissan Chemical Industries, Ltd. "Snowtech-N".

Chemical treatment liquid (B) :

An aqueous solution containing 20 g / l tannic acid, 40 g / l silane binder, 20 g / l fine silica and 20 g / l polyester resin was prepared and used as a pretreatment agent for metals. The tannic acid used is Fujigakug Kogyo Co., Ltd. "Tanic acid AL", and the silane binder -Glycidoxypropyltrimethoxysilane, the fine silica is Nissan Chemical Industries, Ltd. "Snowtech-N", and the polyester resin is Dainippon Ink Chemical Industries, Ltd. "Finetex ES-650".

Chemical treatment solution (C) :

For comparison, "ZM-1300AN" manufactured by Nippon Parkerizing Co., a commercially available chromate treatment solution was used.

Chemical treatment liquid (D) :

For comparison, a commercially available zinc phosphate treatment liquid, "PALBOND" manufactured by Nippon Parkerizing Co., was used.

3. Coating Compositions Containing Aluminum Phosphate

Aluminum phosphate pigments and, if necessary, rust preventive pigments, were added to each of commercially available polyester, urethane, and epoxy clear coating compositions that did not completely contain the pigment, and stirred them to prepare a coating composition. The aluminum phosphate pigment used was "K-G105" manufactured by Daika Corporation. The rust preventive pigments used were "NP-530" from TohoGanryo, zinc ion exchange silica (as "Ca-Si" in the table) as zinc phosphate rust preventive pigments (described as "Zn phosphate" in the table). ) Is a commercially available strontium chromate as Grace's "Shielddex-C303" or chromium-based rust preventive pigments (described as "Sr-Cr" in the table). Each addition amount of these pigments is shown in Table 1. Additionally, if necessary, a sieving pigment is used, and the sieving pigment used is Nippon Aerosil "Aerosil 300" or a white pigment ("Titanium in the table) as commercially available particulate silica (described as" silica "in the table). "CR-95" titanium oxide manufactured by Ishihara Sangyo Co., Ltd.). Each amount of these pigments is shown in the table.

4. Phase Coating Composition

"FL100HQ" from Nippon Paint Co., a commercially available polyester-based phase coating composition, was used. The color is white.

5. Back Coating Composition

"FL100HQ" from Nippon Paint Co., a commercially available polyester-based phase coating composition, was used. The color is gray.

6. Preparation of pre-coated metal sheet

Each metal sheet was degreased by immersing it in an aqueous solution of FC-364S (manufactured by Nippon Parker Co., Ltd.) for 10 seconds at a concentration of 2 mass% and a temperature of 60 ° C, followed by washing with water and drying. The chemical conversion treatment solution (A), (B), (C) or (D) was coated on both surfaces of each metal sheet by a roll coater and dried in a hot air drying furnace to obtain a chemical conversion coating layer. . The amount of the chemical conversion treatment liquid attached is set such that the amount of the total dry film adhered is 200 mg / m ^{2 in} the case of chemical conversion treatment liquids (A), (B) or (D). The chemical conversion treatment liquid (C) is coated so that an adhesion amount of 50 mg / m ² is provided in terms of metal chromium. In the specimen using the chemical conversion treatment liquid (E), the chemical conversion coating layer is obtained by immersing the degreasing metal sheet in the chemical conversion treatment liquid (E) for 2 minutes and drying it in a hot air drying furnace. The chemical conversion treatment liquid (E) is coated so that the amount of zinc phosphate attached is 2 g / m ² . The final sheet temperature at the time of chemical conversion treatment and drying is set at 60 ° C. Thereafter, the resin coating liquid containing the aluminum phosphate pigment was coated on one surface of the metal sheet by a roll coater so as to have a dry thickness of 5 µm, and the backside resin coating composition by the roll coater so as to have a dry thickness of 5 µm. Coated on the other surface of the metal sheet. These resin coating compositions are dried and cured in an induction heating furnace while blowing hot air under the condition that the final sheet temperature of the metal sheet is 210 ° C, thereby obtaining a coating layer. The coated metal sheet after drying and baking is cooled with water by spraying water on top thereof. Subsequently, the phase coating composition is coated on the resin coating layer containing the aluminum phosphate pigment by a roll coater to have a dry thickness of 15 µm, and then blowing hot air under the condition that the final sheet temperature of the metal sheet is 230 ° C. It is dried and baked in an induction furnace. The metal sheet after drying and baking is cooled with water by spraying water on top thereof. In this way, a pre-coated metal sheet is obtained as the material for use in the test.

The following evaluation test is done to the all-coated metal sheet obtained in this way. In any of these tests, the surface of the resin coating layer formed by the resin coating composition containing the aluminum phosphate pigment was used as the surface for evaluation.

1. Adhesion test of processed part of coating

Each pre-coated metal sheet was bent at 180 ° and the coating in the machined portion was observed through a magnifying glass at 20 magnification to check for the presence of cracks in the coating. In the bending test, bending was performed so that the surface coated with the resin coating composition containing the aluminum phosphate-based pigment was on the outside. Moreover, a pressure-sensitive adhesive tape adhered to the workpiece and peeled strongly so that the remaining state of the coating was visually observed. In this test, tape peeling was performed twice. Bending was performed by OT processing (ECCA-T7) in an atmosphere of 20 ° C.

In the evaluation of the cracks of the coating, ◎ when the coating is completely free of cracks, ○ when the coating has about 1 to 3 very small cracks, △ when very small cracks are present throughout the coating, The case where a large crack which can be clearly observed even by the eye exists throughout the processed part of the coating is evaluated as x.

In the evaluation of the remaining state of the coating after tape peeling, when the coating does not peel off and remains on the steel sheet,?, When the part of the coating is slightly peeled off, when the part of the coating is seriously peeled off, the coating When peeling of is observed over the whole process part, it evaluates as x.

Each pre-coated metal sheet after OT processing is immersed in boiling water for 1 hour, then taken out, left for 24 hours and subjected to tape peeling. In the evaluation of the remaining state of the coating, when the coating remains on the plated steel sheet without being electrolytically peeled off, when the portion of the coating is slightly peeled off, when the portion of the coating is seriously peeled off, When peeling is observed over substantially the whole of a process part, it evaluates as x.

2. Coating scratch test by beads.

"Coating Scratch Test Method by Bead", a test method for reproducing the peeling of the coating of the pre-coated metal sheet generated due to scratching of the coating by the mold during press molding of the pre-coated metal sheet. 95-1078). First, the prepared pre-coated metal sheet is cut into specimens of 30 mm (width) x 300 mm (length). This specimen is sandwiched by a flat metal mold and a metal mold provided on top with beads having a radius of 3 mmR. At this time, the specimen was sandwiched so that the beads of the metal mold were pressed against the surface (evaluation surface) of the resin coating layer containing the aluminum phosphate pigment of the specimen, and a load of 1 ton was applied to the evaluation surface of the pre-coated metal sheet. It is applied to press the bead portion. In this state, the pre-coated metal sheet is drawn at a rate of 200 mm / min and the peeling state of the coating on the evaluation surface of the pre-coated metal sheet rubbed by the beads is visually observed and evaluated.

In the evaluation, when the coating did not peel at all, ◎, when the coating was partially peeled off, ○ when the coating corresponding to about 20% or more was peeled off as the area ratio with respect to the portion rubbed by the beads, △, When a coating peels completely, it evaluates as x.

3. Corrosion Resistance Test

On the surface coated with the coating composition containing the aluminum phosphate-based pigment of the prepared pre-coated metal sheet, a cutout is formed by a cutter penetrating the coating to reach the metal sheet. Moreover, the edge portion of the sheet is cut so that the burr formed by cutting reaches the surface coated with the backside resin coating layer (lower burr). Thus, samples for the corrosion resistance test are prepared. The sample is then subjected to a salt spray test according to the method described in JIS K 5400-9.1. Brine is sprayed onto the surface coated with the resin coating composition containing the aluminum phosphate pigment of the sheet. The test time is 120 hours if the blank of the pre-coated metal sheet is a cold rolled steel sheet, 240 hours if the blank is an electrogalvanized steel sheet, and blank is a hot dip galvanized steel sheet, 55% alloy aluminum galvanized steel sheet or Zn-11% aluminum-3% magnesium It is 360 hours if it is a -0.2% silicon plating steel plate.

In the evaluation of the coating at the cutout, when the maximum blister width at one side of the cutout is less than 1 mm,?, When less than 2 to 3 mm, and when less than 3 to 5 mm,?, 5 When mm or more, it evaluates as x.

In the evaluation of the cut-out end face portion, when the blister width from the end face is 2 mm or less, ◎, when it is less than 2 to 3 mm, △ when it is less than 3 to 5 mm, and when it is 5 mm or more, it evaluates as x do.

[table]

[Table (continuous)]

The evaluation results are described below.

The evaluation test results of the prepared pre-coated metal sheet are shown in the table. In the pre-coated metal sheet of the present invention (Examples 1 to 22), the coating is almost in the scratch test of the coating by the beads when compared to the metal sheet using a conventional non-chromate conversion treatment such as zinc phosphate treatment (Comparative Example 28). It did not peel off, and the all-coated metal sheet of this invention turned out to be excellent. In addition, when the aluminum phosphate pigment is not added to the resin coating layer on the chemical conversion treatment layer (Comparative Example 23), or when the aluminum phosphate pigment is added in an amount of less than 1 part by mass per 100 parts by mass of the resin solids (Comparative Example 24). Compared with, the coating hardly peeled off in the scratch test of the coating by the beads, so that the precoated metal sheet of the present invention was found to be excellent. In the pre-coated metal sheet of the present invention, when the chemical conversion coating layer contains a polyester resin, the adhesion of the processed portion of the coating is improved and the coating is difficult to peel off during the coating scratch test by the beads (Examples 1 and 2 of the present invention). 10), and therefore it is more preferred that the chemical conversion treatment coating layer contains a polyester resin. When the rust preventive pigment is added to the coating material in addition to the aluminum phosphate pigment (Examples 8 to 22 of the present invention), the corrosion resistance is improved as compared with the case where no rust preventive pigment is added (Examples 2 to 7 of the present invention), thus coating It is preferred to additionally add rust preventive pigments to the composition. In particular, when the rust preventive pigment is calcium ion exchangeable silica (Examples 1, 8 to 14 and 17 to 22 of the present invention), the corrosion resistance is further improved, and furthermore, when the conventional chromate rust preventive pigment is added (the present invention) Of Example 16 and Comparative Example 26), and it is therefore preferable that the rust preventive pigment is calcium ion exchangeable silica.

According to the present invention, a pre-coated metal sheet excellent in the adhesion and corrosion resistance of the processed portion of the coating and well suited for press molding can be provided without using hexavalent chromium, which is concerned with environmental influences. Thus, the present invention has a very high industrial value.

Claims (10)

On one surface or both surfaces, it has a chemical conversion treatment layer which simultaneously contains at least one of a silane binder, particulate silica, and tannin and tannic acid as a solid content, and 1-140 mass parts of aluminum phosphate pigments per 100 mass parts of resin solid content thereon. The all-coated metal sheet which has the outstanding press formability containing the metal sheet which has a resin coating layer containing. The all-coated metal sheet according to claim 1, wherein the chemical conversion treatment layer further has a polyester resin as a solid content. The pre-coated metal sheet according to claim 1 or 2, wherein the aluminum phosphate pigment resin contained in the resin coating layer is tripolyphosphoric aluminum dihydrogen phosphate. The excellent press-molding according to any one of claims 1 to 3, wherein the resin coating layer further contains an rust preventive pigment, and the total content of the rust preventive pigment and the aluminum phosphate pigment is 140 parts by mass or less per 100 parts by mass of the resin solids. Pre-coated metal sheet having properties. The pre-coated metal sheet having excellent press formability according to claim 4, wherein the rust preventive pigment contained in the resin coating layer is calcium ion exchangeable silica. The pre-coated metal sheet according to any one of claims 1 to 5, wherein the metal sheet is a metal sheet having a plating layer on one or both surfaces thereof. On one or both surfaces of the metal sheet, a treatment liquid containing at least one of a silane binder, fine silica and tannin and tannic acid is coated simultaneously, and the treatment liquid is dried to form a chemical conversion coating layer, and further, the chemical conversion coating layer A method for producing a pre-coated metal sheet having excellent press formability, comprising coating a resin coating composition containing 1 to 140 parts by mass of an aluminum phosphate pigment per 100 parts by mass of a resin solid content, and drying and curing the coating material. 8. The method for producing a pre-coated metal sheet according to claim 7, wherein the treatment liquid has excellent press formability further containing a polyester resin. The coating composition according to claim 7 or 8, wherein the coating composition further contains an rust preventive pigment, and the total content of the rust preventive pigment and the aluminum phosphate pigment is 140 parts by mass or less per 100 parts by mass of the resin solids. Method of manufacturing coated metal sheet. A press-formed pre-coated metal product comprising a press-formed pre-coated metal sheet, wherein the press-formed pre-coated metal sheet is a pre-coated metal sheet according to any one of claims 1 to 6.