JPS6141310B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is characterized in that an adhesive layer is applied to an electrolytic lead-plated steel plate while being held by a non-woven fabric, a decorative paint is applied thereon, and then a weather-resistant film is laminated thereon. The present invention relates to a method for manufacturing a composite laminated steel sheet, and the objective thereof is to provide a method for manufacturing a composite laminated steel sheet that is resistant to scratches on its decorative surface and has excellent corrosion and weather resistance. As one means of imparting corrosion resistance to steel materials, surface-coated steel materials have been widely used, and metal-plated and painted steel materials are particularly representative. However, recently, steel materials have been used for various purposes and are increasingly being used under harsh conditions, so conventional single plating, such as zinc plating, may not always provide satisfactory results. I can't get it. Therefore, a technology has been developed that improves the appearance and corrosion resistance by painting and coloring the galvanized layer after galvanizing, and this technology has been put into practical use as decorative steel sheets and colored galvanized steel sheets. As is well known. However, the problem with these conventional galvanized/painted surface coatings is that zinc itself becomes a sacrificial anode and is easily corroded by corrosive factors such as moisture and oxygen that pass through the coating, and it also produces corrosion products. It is easy for corrosion to increase and corrosion under the paint film to progress quickly. On the other hand, the lead layer of galvanized steel sheets with electrolytic lead plating is electrochemically nobler than the base iron, so typical cathodic type galvanized steel sheets are different from galvanized steel sheets in this respect. are different. For this reason, lead has better corrosion and chemical resistance than bad lead, and even if the paint film deteriorates or defects occur, the highly corrosion-resistant lead will protect the base metal and last for many years. Even if the lead disappears, corrosion will remain in this area and will not promote peeling of the surrounding coating. Moreover, since the surface of this plating layer is covered with a stable film of lead oxide, it has significantly better corrosion resistance than galvanized steel sheets. The reason why coated steel sheets based on electrolytic lead-galvanized steel sheets with excellent corrosion resistance have not been commercialized until now is that the adhesion with the paint film and corrosion resistance could not be improved as in the case of galvanized steel sheets. It was not put to practical use because there was no suitable pretreatment such as zinc phosphate treatment or chromic acid treatment, and no suitable primer. That is, the present invention obtains coating film adhesion equal to or higher than that of galvanized steel sheets by subjecting electrolytic lead-plated steel sheets to a specific pretreatment, and on top of this, an adhesive layer containing a rust-preventing pigment is held with a nonwoven fabric. A composite material that has excellent corrosion resistance and weather resistance, and is resistant to scratches on the base material. This is a method for manufacturing laminated steel sheets. The present invention will be explained in detail below. First, the electrolytic lead-plated steel sheet that is the object of the present invention can be easily plated to a predetermined thickness using conventional electrolytic lead plating methods such as a borofusating bath, a silicate bath, a sulfamic acid bath, and an alkaline bath. However, in the present invention, the plating thickness needs to be 0.1μ or more. If the thickness is less than this, there will be no corrosion resistance under the corrosion-resistant coating, and the function as an electrolytic leaded layer/organic coating system will deteriorate. As for the upper limit of the plating thickness, there is no problem even if it is quite thick, but since it is an electroplating method, the standard is 10μ, and making it thicker than this requires a long time for plating, which is disadvantageous in terms of the process. Of course, even if the plating thickness is greater than this, there will be no problem in terms of corrosion resistance and workability. Furthermore, it is also possible to eutectoid tin, copper, nickel, cobalt, antimony, etc. to the electrolytic lead plating layer itself, or to form a eutectoid plating layer containing various metal oxides dispersed. It works effectively as long as it is used as a parent body. The steel sheet referred to in the present invention may be any of ordinary low carbon steel, copper-containing steel such as weathering steel, cold rolled steel sheet of low alloy steel such as sulfuric acid resistant steel and seawater resistant steel, or pickled hot rolled steel sheet. This also applies to items such as Next, as a pretreatment, an alkaline aqueous solution with a pH of 9 or higher is preferable, but mere immersion cleaning is insufficient and activation of the plated layer surface by alkaline electrolytic cleaning or a strong brushing effect is required. For example 90
Adopt a method of activating the lead metal surface by brushing cleaning with a 3% aqueous solution of sodium orthosilicate (PH13.5) at ℃, followed by electrolytic cleaning with the same solution, followed by hot water cleaning with brushing. It was found that the adhesion of the primer and paint film was equal to or better than that obtained when zinc phosphate treatment was applied to a galvanized steel sheet as a base. In addition, in the case of electroplating as in the present invention, in addition to alkaline degreasing, there is also a method in which the oxide film on the surface of the plating layer is scraped off using a brushing roll containing an abrasive or a buff roll containing an abrasive to expose an active surface. In addition, since electrolytic lead-plated steel sheets usually have defects in the plating film such as pinholes, anti-rust pigments such as zinc chromate, strontium chromate, calcium molybdate, etc. are used to protect the film defects with a primer coating layer. Apply a primer containing anti-rust pigment (e.g., one-component epoxy system, acrylic/epoxy system, two-component acrylic/phenol modified vinyl system, color primer, etc.) to a thickness of 3 to 15μ, and heat at 175 to 240℃. The adhesive layer is formed by baking at a baking temperature of . A nonwoven fabric such as glass wool or polyester having a thickness of 0.035 to 0.3 mm is laminated and adhered to one or both sides of this adhesive layer. Furthermore, a baking type adhesive similar to the above adhesive is applied and baked to form an adhesive layer. In this way, the adhesive layer is applied onto the steel plate while being held in the non-woven fabric. Note that the adhesive layer may be applied only to the steel plate side, or may be applied by impregnating the nonwoven fabric in advance. If the non-woven fabric is pre-impregnated with adhesive, the non-woven fabric is adhered to the steel plate using the impregnated adhesive.
Further, the impregnated adhesive may be used as a binder between the nonwoven fabric and the decorative paint. Next, a decorative paint is applied onto the adhesive layer held by the nonwoven fabric or onto the nonwoven fabric and baked. Vinyl chloride resin sol paint is used as the cosmetic paint, and
Apply at a thickness of 400μ, preferably 100-150μ,
Can be baked at 175-220℃. Next, a transparent film with good weather resistance, such as acrylic, vinyl fluoride, vinylidene fluoride, etc., is layered on top of this decorative paint, and laminated by heat-sealing or via an adhesive layer. For example, if this film is an acrylic film, the thickness is 50 to 200μ, preferably 50 to 200μ.
Laminate at a temperature of 180-240℃ using 75μ. When these decorative paints and films are applied only to one side, a vinyl chloride resin layer with a thickness of 50 to 350 μm or a color top coat with a thickness of 7 to 25 μm is applied to the other side via the same adhesive layer as above. A back coating such as a layer can be applied and baked at 180-220℃. In the above, heat treatments such as baking and lamination are performed for each layer sequentially, but they may be performed all at once after the final layer is formed.
Further, coating can be appropriately employed such as roll dipping spray. In the present invention, as described above, the adhesive is applied to the electrolytic leaded steel plate while it is held in the non-woven fabric, and the decorative paint is applied on top of this, so that a large amount of the adhesive held in the non-woven fabric is applied. At the same time, the decorative paint is not directly adhered to the steel plate by the adhesive, but is adhered to the nonwoven fabric adhered to the steel plate, and the decorative paint does not have good adhesion to the steel plate. It also has the advantage of being able to be firmly and firmly attached. In addition, the presence of the nonwoven fabric layer improves impact resistance, and since the film has good weather resistance, even if the decorative paint lacks weather resistance, film lamination can easily provide excellent weather resistance. can be applied to the decorative surface, and the film can protect the decorative surface and make it resistant to scratches, and a wide variety of decorative paints can be selected and used from the viewpoint of cosmetics and other physical properties. There are advantages. In addition, when vinyl chloride resin is used as a decorative paint, a certain amount of water permeation through the paint film is unavoidable, so when a galvanized steel plate is used as the base, the zinc is electrochemically ionized, resulting in long-lasting effects over many years. During this time, it accumulates in the vinyl chloride film or flows out.
By the way, the metals present in vinyl chloride film, such as zinc, iron, tin, cadmium, nickel, chromium,
The degree of strength of lead that accelerates the deterioration of vinyl chloride is determined by the weather-o-meter deterioration acceleration test, in order of strength: Zn>Fe>Sn>Cd>
Ni>Cr>Pb, and the vinyl chloride film contains zinc, tin,
With copper, almost the entire surface deteriorates and turns black, and significant deterioration of the film is observed, but with nickel, chromium, and lead, only a few black spots appear. Furthermore, since vinyl chloride undergoes a dehydrochloric acid phenomenon during its deterioration process, it is recognized that corrosion of zinc, tin, and copper is significantly accelerated by the generated hydrochloric acid. Galvanized steel sheets with a vinyl chloride coating have the disadvantage that the vinyl chloride coating and the galvanized layer act synergistically, accelerating deterioration and corrosion of both the coating layer and the base. If the base is made of a steel plate, this drawback can be overcome. If a nonwoven fabric made of glass wool or other inorganic fibers is used, various heat treatments can be carried out without difficulty, and the hardness of the adhesive layer is increased, resulting in an even higher surface hardness. The present invention will be specifically described below based on examples. Example 1 After cleaning a cold-rolled steel plate with a thickness of 0.35 mm, electrolytic lead plating was applied to both sides under the conditions shown below.
A composite laminated steel plate having a coating film structure as shown in FIG. 1 was manufactured.

[Table] First, 3% sodium orthosilicate solution (PH13.5) heated to 90°C was applied to the surface of the electro-leaded steel plate 3, which consists of the steel plate 1 and the electro-leaded layer 2, with a nylon brushing roll. After spray cleaning while brushing, electrolytically clean with a solution of the same concentration, and then wash with warm water to form an activated layer 4 on both surfaces of the lead-plated layer 2.
A two-component acrylic/phenol-modified vinyl adhesive containing strontium chromate anti-corrosion pigment was applied to a thickness of 10μ on one side of the surface, and the adhesive was heated at 220°C.
Primer layer 5 was obtained by baking for 1.5 minutes. Next, a glass wool nonwoven fabric 6 with a thickness of 0.1 mm is layered and adhered to one side of the primer layer 5, and the same amount of the same adhesive as above is applied onto this nonwoven fabric 6, and the primer layer 5 is baked under the same conditions. did. Next, on the primer layer 5 held by this non-woven fabric, a vinyl chloride paint is applied as a decorative coating 7 to a thickness of 120μ, and heated to 200°C.
Bake for 1.5 minutes. Here, as this paint
PVC (=1700) 100 parts, DOP 50 parts, dibasic lead phosphite 3 parts, titanium white 25 parts, hydrocarbon solvent 15
A white paint containing the following ingredients was used. Next, an acrylic film 8 having a thickness of 60 μm was placed on top of the polyvinyl chloride resin layer 7, and laminated by heating and pressing at 200° C. for 1.5 minutes. In addition, on the other side of the steel plate, the same adhesive as above was applied as a primer layer 5' to a thickness of 5μ, and after baking under the same conditions, the same vinyl chloride resin sol as above was baked, and then the same adhesive as above was applied. Apply a vinyl chloride resin sol paint to a thickness of 150 μm on the primer layer 5′ as a back coating layer 7′,
Baked at 190°C for 1.5 minutes. Comparing the performance of the composite laminated steel sheet manufactured in this way with that of a vinyl chloride steel sheet with a galvanized steel sheet as the base, the results are shown in the attached table. From this result, a composite laminated steel sheet based on an electrolytic lead-plated steel sheet plated to a thickness of 0.1 to 10 μm was found to be a composite laminated steel sheet that was resistant to scratches and had excellent corrosion and weather resistance.

[Table] Example 2 Example 1 on both sides of weather-resistant copper-containing steel with a thickness of 0.5 mm
Composite laminated steel plates having a coating film configuration as shown in FIG. 2 were manufactured on electrolytic lead-plated steel plates each having a thickness of 5 μm under the same conditions as described above. First, an electrolytic leaded steel plate 3 consisting of a steel plate 1 and an electrolytic leaded layer 2 is immediately polished on both sides with a Scotch brite roll containing an abrasive and washed with hot water to form an activated layer 4 on both surfaces of the leaded layer 2. A 0.1 mm thick glass wool nonwoven fabric was pre-impregnated with an acrylic epoxy adhesive containing a calcium molybdate anti-corrosion pigment on one surface, and the nonwoven fabric 6' was bonded with the impregnated adhesive at 220℃. Bake for 1.5 minutes. Next, vinyl chloride paint was applied to a thickness of 120 μm as the decorative coating film 7 of the primer layer held on this nonwoven fabric, and baked at 200° C. for 1.5 minutes. Here, a white paint mainly composed of 100 parts of PVC (=1700), 50 parts of DOP, 3 parts of dibasic lead phosphite, 15 parts of titanium white, and 15 parts of a hydrocarbon solvent was used. Next, an acrylic/epoxy adhesive was applied to a thickness of 5μ on top of the vinyl chloride resin decorative coating 7.
Baked at 200℃ for 1.5 minutes to form a primer layer of 5", and a 38μ thick vinyl fluoride resin film 8' on the surface.
were stacked on top of each other and bonded by heating and pressing at 210°C for 1.5 minutes. On the other side of the steel plate, apply the same acrylic/epoxy adhesive as above to a thickness of 5μ as primer layer 5, bake at 200°C for 1.5 minutes, then apply vinyl chloride paint as above to primer layer 5. Coat it on top as back coating layer 7' to a thickness of 150μ and heat it at 190℃.
Bake for 1.5 minutes. The performance of the composite laminated steel sheet manufactured in this way was similar to that of Example 1, and a composite laminated steel sheet that was less prone to scratches and had excellent corrosion and weather resistance was obtained.

[Brief explanation of the drawing]

FIGS. 1 and 2 are cross-sectional views showing embodiments of the steel plate of the present invention. DESCRIPTION OF SYMBOLS 1... Steel plate, 2... Electrolytic lead-plated layer, 3... Electrolytic lead-plated steel plate, 4... Activation layer, 5, 5', 5'', 5...
Primer layer, 6, 6'... Nonwoven fabric layer, 7... Decorative coating layer, 7'... Back coating layer, 8, 8'... Film layer.

Claims (1)

[Claims] 1. The surface of the lead-plated layer of an electroplated steel plate obtained by plating lead on a thin steel plate to a thickness of 0.1 to 10μ using the electroplating method is activated by brushing and polishing or alkaline electrolytic cleaning. , is characterized in that an adhesive layer containing anti-rust pigment is applied on top of the adhesive layer while being held by a non-woven fabric, a decorative paint is applied on top of the adhesive layer, and then a weather-resistant film is laminated on top of the adhesive layer. Manufacturing method for composite laminated steel sheets.