JPS6141309B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to the production of a decorative steel sheet, which is characterized in that an adhesive layer is formed on an electrolytic lead-plated steel sheet while the adhesive layer is held by a non-woven fabric, and then a film with good weather resistance is laminated thereon. The purpose of this method is to provide a method for manufacturing a decorative steel sheet that can easily produce a decorative 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 representative examples thereof. However, recently, steel materials have been used for a variety of purposes and are increasingly being used under harsh conditions, so conventional single plating, such as zinc plating, does not necessarily yield satisfactory results. do not have. Therefore, after further galvanizing,
It is well known that a technology has been developed to improve the appearance and corrosion resistance by painting and coloring the galvanized layer, and this technology has been put into practical use as decorative steel sheets and colored galvanized PVC steel sheets. . 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 corrosion is generated. The problem is that the corrosion under the paint film is likely to progress quickly. On the other hand, in galvanized steel sheets that are electrolytically plated, the lead layer is electrochemically nobler than the base iron, so typical cathodic type galvanized steel sheets have this point. It is different from a steel plate. For this reason, lead has better corrosion and chemical resistance than zinc. For example, even if the paint film deteriorates or defects occur, the highly corrosion-resistant lead protects the base metal and will last for many years. Even if the lead disappears, corrosion will remain in this area and will not promote peeling of the surrounding coating. However, 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. In other words, the present invention provides coating film adhesion equal to or better than that of galvanized steel sheets by subjecting electrolytic lead-galvanized steel sheets to a specific pretreatment, and on top of this, an adhesive layer containing anti-corrosion pigments is held with a non-woven fabric. This is a method for manufacturing a decorative steel sheet, which is characterized by having excellent corrosion resistance and weather resistance, and being resistant to scratches on the base material, by applying it in a coated state and laminating a film with good weather resistance thereon. 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 boufating 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. Regarding the upper limit of the plating thickness, there is no problem even if it is quite thick, but since it is an electroplating method, it is 10μ.
is used as a guideline, and making it thicker than this will require 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. In addition, the electrolytic lead plating layer itself contains tin, copper, nickel,
It is also possible to use gobalt, antimony, etc. as the eutectoid plating layer, or to use various metal oxides dispersed as the eutectoid plating layer, and as long as the electrolytic lead plating layer is used as the base material, it will work effectively. In addition, the steel plate referred to in the present invention may be a copper-containing steel such as ordinary low carbon steel or weather-resistant steel,
This applies to cold-rolled low-alloy steel sheets such as sulfuric acid-resistant steel and seawater-resistant steel, as well as pickled hot-rolled steel sheets. 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, a 3% aqueous solution of sodium orthosilicate (PH
In 13.5), after brushing and cleaning, the surface of the lead-plated layer is activated by electrolytic cleaning with the same solution, followed by hot water cleaning with brushing. It was found that the adhesion of the brimer and coating film was equal to or better than that obtained with the treatment. In addition, in the case of electroplating as in the present invention, in addition to alkaline electrolytic cleaning, 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, electrolytic lead-plated steel sheets usually have defects in the plating film such as pinholes, so anti-rust pigments are added to protect the film defects with a primer coating layer.
For example, zinc chromate, strontium chromate,
Apply a primer containing anti-rust pigment such as calcium molybdate (e.g. one-component epoxy system, acrylic epoxy system, two-component acrylic/phenol modified vinyl system, etc.) to a thickness of 1 to 15 μm and heat at 175 to 240℃. An adhesive layer is formed by baking at a baking temperature. 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 by the non-woven fabric. On the steel plate side, the adhesive layer may be applied only to the steel plate, or may be applied by impregnating the nonwoven fabric in advance. When the nonwoven fabric is impregnated with an adhesive in advance, the nonwoven fabric may be adhered to a steel plate with the impregnated adhesive, and the impregnated adhesive may be used as a binder between the nonwoven fabric and the synthetic resin film. Next, an acrylic film (thickness 50 to 200 μm) or a fluorinated vinyl film (thickness 25 μm) is placed on the adhesive layer held on this nonwoven fabric or on the nonwoven fabric.
A synthetic resin film with weather resistance and heat resistance, such as 75μ), is laminated at a temperature of 180℃ to 240℃. On the other hand, if the adhesive layer and film layer are applied only to one side of the steel plate, the other side may be coated with a vinyl chloride resin layer with a thickness of 50 to 350 μm or a color layer with a thickness of 7 to 25 μm. A back coating such as a top coat layer can be applied and baked at 180°C to 240°C. In the above, heat treatments such as baking and lamination are performed sequentially for each layer, but the adhesive layer held on the nonwoven fabric may be subjected to wet, on, and wet treatments all at once. Moreover, the coating method can be appropriately employed such as a roll method, a dipping method, and a spray method. In the present invention, as described above, an adhesive is applied to an electrolytic leaded steel plate while it is held in a nonwoven fabric, and a synthetic resin film is laminated on top of the adhesive.
The synthetic resin film is bonded through a large amount of adhesive held by the non-woven fabric, and the synthetic resin film is not directly bonded to the steel plate by the adhesive, but is bonded to the non-woven fabric that is bonded to the steel plate. This method has the advantage that even synthetic resin films with poor properties can be firmly and firmly attached. In addition, it is possible to obtain a decorative steel sheet that has improved impact resistance due to the presence of a nonwoven fabric layer, has elasticity, and is protected by a scratch-resistant synthetic resin film. The synthetic resin film is less likely to be scratched even when exposed to sunlight, and since the synthetic resin film is UV resistant and heat resistant, a decorative steel sheet with excellent weather resistance can be obtained. Furthermore, despite such excellent properties, decorative steel sheets can be easily obtained. 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 decorative steel sheet having a coating film structure as shown in FIG. 1 was manufactured.

[Table] First, 3% sodium orthosilicate solution (PH13.5) was heated to 90°C on the surface of an electrolytic leaded steel plate 3 consisting of a cold rolled steel plate 1 and an electrolytic leaded layer 2. Spray cleaning while brushing with a single roll, electrolytically cleaning with a solution of the same concentration, then washing with warm water, forming an activation layer 4 on both surfaces of the lead-plated layer 2, and applying strontide to one side that will become the surface. A two-component acrylic/phenol modified vinyl adhesive containing Yumuchromate anti-corrosion pigment was applied to a thickness of 10μ and baked at 220°C for 1.5 minutes to form primer layer 5. 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. And so. Next, an acrylic film 8 having a thickness of 75 μm was placed on the primer layer 5' held by this nonwoven fabric, and laminated by heating and pressing at 200° C. for 1.5 minutes. On the other hand, on the other surface where the glass wool nonwoven fabric is not bonded, the same adhesive as above was applied as a primer layer 5'' to a thickness of 5μ, baked under the same conditions, and then vinyl chloride sol paint was applied to a thickness of 150μ. 200
A back coating layer 7 was obtained by baking at ℃ for 1.5 minutes. Here, the composition of the vinyl chloride sol paint used was P,
V, C (P=1700) 100 parts, DOP 50 parts, dibasic lead phosphite 3 parts, titanium white 15 parts, hydrocarbon bath agent 15
This is a white vinyl chloride sol that mainly contains
Comparing the performance of the decorative steel sheet manufactured in this way with that of a vinyl chloride-coated steel sheet with a conventional galvanized steel sheet as a base, the results are shown in the attached table. These results show that decorative steel sheets based on electrolytic lead-plated steel sheets plated to a thickness of 0.1 to 10 μm are resistant to scratches and have excellent corrosion and weather resistance.

[Table] Example 2 A coating film as shown in Fig. 2 was applied to both sides of weather-resistant copper-containing steel with a thickness of 0.5 mm and electrolytic lead plated with a thickness of 5 μm under the same conditions as in Example 1. A decorative steel plate with the following configuration was manufactured. First, both sides of an electrolytic leaded steel plate 3 consisting of a weather-resistant copper-containing steel plate 1 and an electrolytic leaded layer 2 are polished using a Scotch Bright Roll containing an abrasive and washed with hot water to make both surfaces of the leaded layer 2 active. Form layer 4, pre-impregnate a glass wool nonwoven fabric with a thickness of 0.1 mm with an acrylic adhesive containing calcium molybdate anti-rust pigment on one surface, and attach the nonwoven fabric 6' to a steel plate using the impregnated adhesive. Glue at 220℃
Bake for 1.5 minutes. Next, a vinyl fluoride resin film 8' having a thickness of 38 μm was layered on the primer layer held by this nonwoven fabric and laminated by heating and pressing at 220° C. for 1.5 minutes. On the other hand, the two-component acrylic phenol-modified vinyl adhesive containing the strontium chromate anti-rust pigment used in Example 1 was applied to the other surface to which the glass wool nonwoven fabric was not bonded to a thickness of 5 μm at 220°C for 1.5 minutes. Baked primer layer 5″, on top of which 100 parts of PVC (P=1700), DOP50
A vinyl chloride paint consisting of 3 parts of dibasic lead phosphite, 15 parts of titanium white, and 15 parts of a hydrocarbon solvent was applied to a thickness of 150 μm and baked at 200° C. for 1.5 minutes to form the back coating layer 7. The performance of the decorative steel sheet produced in this way is similar to that of Example 1, and the decorative steel sheet is hard to get scratches and has excellent corrosion resistance and weather resistance.

[Brief explanation of the drawing]

FIGS. 1 and 2 are cross-sectional views showing embodiments of the decorative steel sheet 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''... Primer layer, 6, 6'... Non-woven fabric, 7... Back coating layer ,
8, 8'...Film layer.

Claims (1)

[Scope of Claims] 1. The surface of the lead-plated layer of an electro-leaded steel plate obtained by plating lead on a thin steel plate to a thickness of 0.1 to 10 μm by electroplating method is subjected to brushing polishing or alkaline electrolytic cleaning. The surface is activated, and an adhesive layer containing anti-rust pigment is held on top of the non-woven fabric to form an adhesive layer.A synthetic resin film having UV resistance and heat resistance is then laminated on top of the adhesive layer. A method for manufacturing a decorative steel sheet, characterized by: 2. The method for producing a decorative steel sheet according to claim 1, wherein the synthetic resin film having UV resistance and heat resistance is an acrylic film. 3. The method for producing a decorative steel sheet according to claim 1, wherein the synthetic resin film having UV resistance and heat resistance is a fluorinated vinyl film.