JPS6051424B2 - Synthetic resin coated decorative steel sheet and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a synthetic resin-coated decorative steel sheet in which a composite film is formed on the surface of a turn sheet by a vinyl chloride film and a highly weather-resistant synthetic resin such as acrylic resin or fluororesin, and a method for manufacturing the same. The main objective is to obtain a decorative steel sheet with good workability and excellent corrosion resistance and weather resistance.

Conventionally, vinyl chloride-coated steel sheets used as decorative steel sheets are based on galvanized steel sheets, and the galvanized surface is subjected to chemical conversion treatment such as zinc phosphate treatment or chromic acid treatment, and then an adhesive is applied on top. , form an adhesive layer by baking,
It is manufactured by baking-coating a polyvinyl chloride sol paint thereon at a thickness of 100 to 400 microns, or by laminating a polyvinyl chloride film with a thickness of 100 to 400 microns.

In both cases, galvanized steel sheets are used as the base metal, so the corrosion resistance, weather resistance, and water resistance of the vinyl chloride coating, and the corrosion resistance of the galvanized steel sheets, that is, the corrosion resistance of the galvanized steel sheets, that is, the zinc It is combined with the function of protecting the base metal by being eluted as a sacrificial anode, exhibiting excellent corrosion resistance and weather resistance, and is widely used as decorative steel sheet for exteriors. However, since the thickness of the vinyl chloride coating on galvanized steel sheets is usually about 100 to 200 μm, a certain amount of water permeation is unavoidable, and zinc is electrochemically ionized and remains for many years. During this period, the vinyl chloride may move through the coating and run off, and impurities in rainwater may accumulate, and ultraviolet rays, heat, and oxygen in sunlight accelerate the decomposition of polyvinyl chloride, and as a result, the zinc in the galvanized layer is decreasing. This deterioration of polyvinyl chloride is not only caused by zinc oxides and hydroxides, but is also thought to be accelerated by the action of metal ions under the influence of ultraviolet rays in sunlight and heat. By the way, metals present in polyvinyl chloride coatings, such as zinc, iron, tin, cadmium, nickel,
Among chromium and lead, the degree of strength that accelerates the deterioration of polyvinyl chloride is determined in the order of strength according to the deterioration acceleration test using a weatherometer: Zn>Fe>Sn>Cd>N1
〉Cr>Pb, and almost the entire surface of the vinyl chloride film turns black due to deterioration due to zinc, tin, and copper, and significant deterioration of the film is observed, but nickel, chromium, and lead only slightly deteriorate. The extent is such that spot-like black dots occur. Furthermore, since vinyl chloride undergoes dehydrochlorination phenomenon during its deterioration process, it is recognized that the corrosion of zinc, tin, and copper is significantly accelerated by the generated hydrochloric acid. This has the disadvantage that the vinyl coating and the galvanized layer act synergistically to accelerate deterioration and corrosion of both the coating layer and the base. Turn sheets, on the other hand, are surface-treated copper plates made by plating lead-tin alloy (turn metal) onto cold-rolled steel sheets by hot-melting or electroplating. Because it is electrochemically noble compared to iron, it is a typical soldering type surface-treated steel sheet, and in this respect it differs from galvanized steel sheet. For this reason, turn metal has better corrosion and chemical resistance than zinc, and when coated with vinyl hexachloride, it is almost resistant to hydrochloric acid generated by the decomposition of polyvinyl chloride as mentioned above. Don't react. Also, although the galvanized layer acts as a sacrificial anode and protects the steel,
It also has a negative impact on polyvinyl chloride because a large amount of corrosive products are generated. However, since turn metal itself has excellent corrosion resistance, it hardly produces corrosion products and does not have any adverse effect on the PVC coating. Further, even if lead ions are eluted into the polyvinyl chloride coating, the effect of deterioration is extremely small as shown in the Weather-O-meter results as described above. As mentioned above, PVC-coated steel sheets based on turn sheets are expected to have superior properties, but until now, as in the case of galvanized copper sheets, appropriate surface treatments such as zinc phosphate treatment or chromic acid treatment have not been applied. Because there is no treatment or adhesive, and because the surface hardness of the turn metal plating layer is low and conventional acrylic or polyester coatings have a film thickness of around 20 μm, the coating is affected by the hardness of the surface of the plating layer. It had the disadvantage of low film hardness and was prone to scratches, so it was not put into practical use. The present invention utilizes the good compatibility of turn metal with polyvinyl chloride and the good corrosion resistance and chemical resistance of turn metal itself, and also improves the adhesion between the turn sheet and the adhesive. This was achieved with the focus on using synthetic resin films that are highly resistant to UV rays and heat, such as fluororesin films and fluororesin films, to protect them and withstand long-term outdoor use. As a method to improve the adhesion with the adhesive, the turn sheet is electrolytically cleaned with an alkaline solution, for example, with a sodium orthosilicate solution, and then washed with hot water to activate the surface of the turn metal. It has been found that adhesion with adhesives is equal to or better than that obtained when a galvanized steel plate is treated with zinc phosphate.

In addition, turn sheets usually have film defects such as pinholes, and the base metal preferentially elutes through these film defects, so anti-rust pigments are used as an adhesive to protect the film defects of the turn metal. If an acrylic-epoxy adhesive or an acrylic-phenolic adhesive is used, adhesion and corrosion resistance will be improved. The present invention will be explained in detail below based on examples. [Example 1] A turn metal plating layer 2, which is a metal alloy layer of 85% lead and 15% tin, is applied to both sides of a steel plate 1 with a thickness of about 10 μm by hot-dipping or electrolytic plating on both sides of a steel plate 1 with a thickness of 0.4 mm. formed to a thickness of
The obtained turn sheet 3 is electrolytically cleaned with a 5% sodium orthosilicate solution, and then the surface of the turn metal plating layer 2 is activated to form an active layer 4. Apply acrylic/phenol-modified vinyl adhesive to a thickness of approximately 10 μm on the plate, and
．． The adhesive layer 5 is formed by powder baking, and then a vinyl chloride sol paint with the following composition is applied to the surface to a thickness of about 150μ using a coating roll, and baked at a board temperature of 190°C for 1.5 minutes to form a vinyl chloride coating. A layer 6 is formed on top of which a layer 6 has a thickness of 50 mm.
μ's Acrylic Film 7 (Product Name Sanjiyuren SDOO)
2 films) were stacked and laminated under pressure at 190°C.

On the back side, a coating layer 9 of an oil-free polyester coating or a urethane coating was formed via a coating layer formed by primer coating. Composition of vinyl chloride sol paint Vinyl chloride resin (P=1700) 10 salivary parts *DOP65〃
Tin Mercaptite 3 〃Titanium White 15〃The various properties such as corrosion resistance and weather resistance of the vinyl chloride coated steel sheet obtained as above are compared with those based on conventional galvanized steel sheets as shown in Table 1. Shows excellent results as shown in .

In the table, ◎ indicates excellent, O indicates good, Δ indicates acceptable, and × indicates poor.

*In terms of marking workability, both were the same in appearance, but 1
When observing the processed part of the material after 800° close bending under a microscope, as shown in Figure 2 A and F), many microcracks occurred in the plating layer in the vinyl chloride-coated galvanized steel sheet in a, while in b. This is not observed at all in the decorative steel sheet based on the turned sheet of the present invention shown in Figure 2, and this appears as a large difference in the corrosion resistance of the processed parts. [Example 2] A turn metal plating layer 2, which is a metal alloy layer of 95% lead and 5% tin, is formed on both sides of a steel plate 1 with a thickness of 0.47T0n (7) to a thickness of about 10μ on both sides. The surface of the turn sheet 3 is brushed to make it moderately rough, electrolytically cleaned with a 13% sodium orthosilicate solution, and then washed with hot water to activate the surface of the return metal plating layer 2 and form the active layer 4.
Then, on one side of this turn metal plating layer 2, an acrylic/phenol-modified vinyl adhesive containing the following rust-preventing pigment was applied to a thickness of about 10 μm, and the plate temperature was set at about 220°C. The adhesive layer 5 was formed by powder baking.

Next, a vinyl chloride sol paint having the following composition was applied to the surface with a coating roll to a thickness of 150μ, and the plate temperature was 190°C.
A vinyl chloride coating layer 6 is formed by powder baking, and an acrylic/epoxy adhesive is applied to the vinyl chloride coating layer 6 to a thickness of approximately 7 μm, and then heated at 210° C. for 1.5 minutes to further thicken the layer. A fluorinated vinyl resin film 7 with a diameter of 38 μm was layered, and
This was laminated under pressure at °C. Acrylic with anti-rust pigment
Phenol-modified vinyl adhesive composition Main resin Acrylic solvent composition Xylene 37% Methyl cellosolve 56%r
! 4EK 7% anti-rust pigment Strontium chromate 5% To 8 Viscosity 300-600cpS Specific gravity 1.10
~1.14 Composition of vinyl chloride sol paint Vinyl chloride resin (P=1700) 10 parts DO
P. DUP65 Lead/Tin/Ba. Zn7〃Titanium white 15〃The corrosion resistance, weather resistance, chemical resistance, and gas resistance of the vinyl chloride coated steel sheet based on the thus obtained turn sheet are higher than that of the vinyl chloride coated steel sheet based on the conventional galvanized steel sheet. As shown in Table 2, it was very superior to coated steel sheets.

The marks ◎, O, Δ, and × in the table indicate the same determination results as above.

Incidentally, the alloy ratio of the turn metal is not limited to the above two examples, and an alloy of 2 to 30% tin, 70 to 98% lead, and a trace amount of zinc or other metals may be used.

The reason why the lower limit of tin is 2% and the upper limit is 30% is that if it is less than 2%, the adhesion of turn plating will be poor, and if it is more than 30%, it will be expensive and the workability will be poor.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the present invention, Fig. 2a is a micrograph showing a bent portion of a vinyl chloride coated steel plate based on a conventional galvanized steel plate, and Fig. 2b is a book. It is a micrograph diagram showing a bent part of a decorative steel plate based on the turn sheet of the invention, in which 1 is a steel plate, 2 is a turn metal plating layer, 3 is a turn sheet, 4 is an oxidized annealing layer,
5 is an adhesive layer, 6 is a vinyl chloride coating layer, and 7 is a synthetic resin film.

Claims (1)

[Claims] 1. A turn sheet in which the surface of a steel plate is coated with a turn metal, a polyvinyl chloride coating laminated on an active layer formed on the turn metal surface via an adhesive layer, and a polyvinyl chloride coating laminated on the polyvinyl chloride film. A synthetic resin-coated decorative steel sheet characterized by being composed of a highly weather-resistant synthetic resin film such as acrylic resin or fluororesin. 2. The synthetic resin-coated decorative steel sheet according to claim 1, wherein the adhesive layer is made of an adhesive containing a rust-preventing pigment. 3. The surface of the turn metal plating layer of the turn sheet obtained by plating and coating a thin steel plate with turn metal is washed with alkali to activate it to form an active layer, and after applying an adhesive and baking it, A method for manufacturing a synthetic resin-coated decorative steel sheet, which comprises applying a polyvinyl chloride sol paint, baking it, and then laminating a weather-resistant synthetic resin film such as acrylic resin or fluororesin thereon. 4. The method for manufacturing a synthetic resin-coated decorative steel sheet according to claim 3, characterized in that the surface of the turn metal plating layer is subjected to electric field cleaning with a sodium orthosilicate solution. 5. The method for manufacturing a synthetic resin-coated decorative steel sheet according to claim 3, characterized in that an adhesive containing an anti-rust pigment is applied onto the turn metal plating layer.