JPH10249995A - Thermoplastic resin-coated metal plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic resin-coated metal plate having excellent chemical resistance and solvent resistance similarly at a repairing part near a welded part to the other part by facilitating a repairing work near the welded part. SOLUTION: This metal plate is covered at least on one surface of the lengthy plate 1 with a thermoplastic resin film 2 except a bared part having a width of 10 to 50mm at both lateral ends of the plate 1. Further, the film 2 is covered with a wide thermoplastic resin film 3 extended to outside of 3 to 30mm from the lateral both ends of the plate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a metal sheet coated with a thermoplastic resin. More particularly, the present invention relates to a thermoplastic resin-coated metal sheet which is suitable for manufacturing a pail can, a gallon can, and the like, has excellent corrosion resistance and seam welding workability, and can easily repair the vicinity of a seam weld after welding.

[0002]

2. Description of the Related Art Conventionally, pail cans, gallon cans, and the like are coated with a thermoplastic resin film having excellent chemical resistance, solvent resistance, etc. on a surface in contact with the stored material so as not to be corroded by the material stored in the can. The used resin-coated metal plate is used. However, when a conventional resin-coated metal plate is used, it is unavoidable that the coating near the seam weld is broken or damaged. As a method of repairing the coating thus damaged or damaged, (a) a method of applying a coating of a thermoplastic resin or a thermosetting resin, (b) a method of heat welding a tape-shaped thermoplastic resin film, c) A method of melt coating with a resin powder (see Japanese Patent Publication No. 1-60310) has been proposed in the past.

However, according to these conventional methods,
Each of (a) to (c) has the disadvantage that the repair work is complicated and the efficiency of the can-making operation is poor. Further, there is a disadvantage that the corrosion resistance of the portion repaired by the above method cannot be sufficiently improved, and that the repaired portion cannot be completely prevented from being corroded by the stored material.

[0004]

Under such circumstances, the present inventors have made intensive studies to provide a technique for eliminating the above-mentioned disadvantages of the conventional method, and as a result, completed the present invention. An object of the present invention is to solve the following problems. 1. An object of the present invention is to provide a thermoplastic resin-coated metal plate that can easily repair a coating near a welded portion. 2. To provide a thermoplastic resin-coated metal sheet in which a repaired portion near a welded portion can obtain a product excellent in chemical resistance, solvent resistance, and the like as in other portions.

[0005]

In order to solve the above-mentioned problems, according to the present invention, at least one surface of a long metal plate (A) has a width of 10 to 10 at both ends in the width direction of the metal plate (A). 50
The thermoplastic resin film (B) is covered except for a bare surface portion of mm, and further extends on the thermoplastic resin film (B) by 3 to 30 mm outside both ends in the width direction of the metal plate (A). The present invention provides a thermoplastic resin-coated metal sheet, which is formed by being covered with a wide thermoplastic resin film (C).

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
In the thermoplastic resin-coated metal plate according to the present invention (hereinafter sometimes simply referred to as “resin-coated metal plate”), the metal plate (A) may be a chin-free steel plate, a tin-plated steel plate, a nickel-plated steel plate, A surface-treated steel sheet whose surface has been subjected to chemical treatment such as electrolytic chromic acid treatment or phosphate treatment, a lower layer of chromium metal, an upper layer of a two-layer structure of chromium hydrated oxide, a tin-free steel sheet, aluminum (alloy ) Plate and the like. In the present invention, the type of the metal plate (A) is not limited to those described above. Of the above examples, a chin-free steel plate is preferred.

The metal plate (A) usually has a long strip shape. The thickness of the metal plate varies depending on its use, the size of the product, etc., but is in the range of 0.20 to 2 mm, and the width is 50 mm to 20 mm.
It is selected in the range of 0 cm. The metal plate (A) may be simply referred to as “coating (B)” hereinafter. For the purpose of improving the adhesiveness with｝, it may be degreased by a washing treatment or applied with an anchor coat agent in advance. In order to cover the surface of the metal plate (A) with the film (B), a method using heat welding, a method using an adhesive, or the like can be used. In the latter case, usable adhesives include epoxy adhesives, phenolic adhesives, amide adhesives, urethane adhesives, acid-modified olefin adhesives, copolyester adhesives, copolyamide adhesives, And mixtures thereof. The type of the adhesive is not limited to those exemplified above.

The thermoplastic resin film (B) covering at least one surface of the metal plate (A) has a function of covering the surface of the metal plate and improving corrosion resistance. When coating the metal plate (A) with the coating (B), the metal plate (A) is coated on both ends in the width direction, leaving a bare surface portion of 10 to 50 mm. The bare surfaces at both ends in the width direction of the metal plate (A) are portions to be overlapped when the ends of the metal plate (A) are welded to each other. In many cases, it is necessary to ensure conductivity. If the width of the bare surface is less than 10 mm, the coating near the weld may deteriorate due to high heat during welding, and if it exceeds 50 mm, the work of repairing the coating near the weld becomes complicated, and neither is preferable. .

The thickness of the thermoplastic resin film (B) varies depending on the type of the thermoplastic resin, the use of the resin-coated metal plate, and the like, but can be selected in the range of 5 to 50 μm. Thickness 5
When the thickness is less than μm, the film forming operation is difficult, and the coating operation on the surface of the metal plate is also difficult. When the thickness exceeds 50 μm, it is not economical and neither is preferable.

The resin constituting the coating (B) includes (i)
Polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-
Acrylic ester copolymers, ionomers, olefin resins such as acid-modified olefin resins obtained by modifying these resins with unsaturated carboxylic acids such as maleic anhydride or derivatives thereof, (ii) polyethylene terephthalate, polybutylene terephthalate, Ethylene terephthalate /
Polyesters such as isophthalate copolymer, (iii)
Polyamides such as nylon-6, nylon-66, nylon-11, nylon-12, (iv) polyvinyl chloride,
And polyvinyl acetate. The type of resin is not limited to those exemplified above.

[0011] Thermoplastic resin coating (C) covering the surface of coating (B)} Hereinafter, it may be simply referred to as "coating (C)".被覆 covers the metal plate surface to further improve corrosion resistance,
Further, it functions as a coating for repairing a welded portion after welding. The coating (C) is coated and adhered to the entire surface of the coating (B), but is not adhered to the bare surfaces at both ends in the width direction of the metal plate (A) and is left free. The reason is that, when the both ends of the metal plates are overlapped and welded, if there is a coating (C) having excellent insulation properties between the two metal plates, it is impossible to employ a welding method for conducting electricity. It is.

The coating (C) is wider than the metal plate (A), and extends beyond the bare surface of the metal plate (A) by 3 mm from both ends in the width direction.
Extend to the outside by about 30 mm and leave it as a free end. The width of the free end extending outward from both ends in the width direction of the metal plate (A) is 3
If it is less than mm, the function of repairing the welded portion cannot be sufficiently exhibited, and if the width of the free end exceeds 30 mm, the workability at the time of repairing is poor, and both are not preferred.

The resin constituting the film (C) may be the same as the resin constituting the film (B). The thickness of the coating (C) varies depending on the type of the thermoplastic resin, the use of the thermoplastic resin-coated metal plate, and the like, but can be selected in the range of 5 to 100 μm. When the thickness of the coating (C) is less than 5 μm, it is difficult to form a film, and it is difficult to coat the surface of the metal plate. When the thickness exceeds 100 μm, it is not economical.
Neither is preferred.

The film (C) can be adhered to the surface of the film (B) by a method using an adhesive in addition to a method of heat welding. In the latter case, usable adhesives include epoxy adhesives, phenolic adhesives, amide adhesives, urethane adhesives, acid-modified olefin adhesives, copolyester adhesives, copolyamide adhesives, And mixtures thereof. The adhesive is not limited to those exemplified above. It is preferable to select an adhesive that provides high adhesive strength according to the combination of the thermoplastic resin constituting the coating (B) and the coating (C).

[0015] The thermoplastic resin-coated metal sheet according to the present invention comprises:
At least one surface is coated with the coating (B) and the coating (C), and when only one surface is coated with these two types of coatings, the remaining surface is coated with the coating (B) or the protective coating (D). It is preferable to keep it. Examples of the protective coating (D) include an epoxy-urea-based baked coating film and an epoxy-phenol-based baked coating film. The thickness of this protective film can be usually selected in the range of 3 to 10 μm.

The operation of welding the ends of the thermoplastic resin-coated metal sheet according to the present invention will be described based on the case of making a can. First, a strip-shaped thermoplastic resin-coated metal plate is cut to the height (length) of a can. Next, this metal plate (A)
Is bent into a columnar shape or a prismatic shape, and both ends (bare surface portions) in the width direction not covered with the coating (B) and the coating (C) are overlapped, and both surfaces of the overlapped portion are welded. Welding methods include fusion welding, crimping, forging,
Examples include a brazing method and a thermal spraying method. Among them, the fusion welding method in which electricity is supplied is preferable.

In the case of the fusion welding method, electrodes are arranged on both surfaces of the overlapped portion, and current is applied between the electrodes to perform seam welding.
At this time, it is preferable to bend the coating (C) in a direction away from the electrode so that the free end does not come into contact with the electrode or approach the electrode too much. After seam welding of both ends (bare surface) in the width direction, the bending of the free end of the coating (C) is released and extended over the welded portion, and the heated portion is locally heated to cover the welded portion and its vicinity. In addition, the vicinity of the seam weld can be easily and reliably repaired.

The thermoplastic resin-coated metal sheet according to the present invention comprises:
Applications requiring corrosion resistance, such as chemicals, pharmaceuticals, paints,
Used as a material for manufacturing pail cans and gallon cans that store various chemicals such as adhesives and detergents, and foods such as mayonnaise, butter and margarine for business use, as well as for manufacturing kitchen parts and building parts Examples of the material include uses.

FIG. 1 is a cross-sectional view of an example of a thermoplastic resin-coated metal plate according to the present invention, and FIG. 2 is an enlarged cross-sectional view showing a process of welding the ends of the thermoplastic resin-coated metal plate.
FIG. 3 is an enlarged sectional view of the vicinity of the weld. In the figure, 1
Is a metal plate, 2 is a thermoplastic resin film (B), 3 is a thermoplastic resin film (C), 4 is a bare surface portion, 5 is a free end of the film (C), 6 is an electrode, 7 is a welded portion, 8 is a welded portion. It is a repair department.

FIG. 1 shows an example of a product in which a thermoplastic resin film is formed on only one surface of the metal plate 1. One side of the metal plate 1 (having a width a) is 3 to 30 times larger than the width of the metal plate 1.
It is covered by a coating (B) 2 having a narrow width of mm. At both ends in the width direction of the metal plate 1, bare surfaces 4 not covered by the coating (B) 2 are formed with substantially the same width.
The upper surface of the coating (B) 2 is covered and adhered by a coating (C) 3. The coating (C) 3 has a width 10
The width of the metal plate 1 is set to be wider by about 50 mm so as not to adhere to the bare surface 4 of the metal plate 1.

When welding the ends of the product shown in FIG. 1, as shown in FIG. 2, the bare surfaces 4 of the metal plate 1 are joined together with the free end 5 of the coating (C) bent. The overlapped portion is sandwiched between the electrodes 6, and electricity is supplied to the electrode 6 to weld the overlapped portion. After welding the overlapped portion, the bent free end 5 is released to form a weld 7
To cover the weld and its vicinity, and by locally heating this part, the free end 5 can be heat-welded. As shown in FIG. 3, the weld and its vicinity are surely repaired. be able to. When a thermoplastic resin film is formed on both surfaces of the metal plate 1, the free end 5 of the film (C) may be bent, and the repair work may be performed on both surfaces of the overlapped portion of the metal plates 1.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. However, the present invention is not limited to the examples described below unless departing from the gist.

[Example] <Preparation of Welding Can> A 50 μm thick plate was prepared on one side of a 0.32 mm thick chin-free steel plate (902 mm × 353 mm), leaving 10 mm bare surfaces at both ends in the longitudinal direction. Carboxyl group-containing polyethylene film (modified PE film)
(Made by Mitsui Petrochemical Co., Ltd., trade name: ADMER NE050). On this film, width 905mm, thickness 80
A μm polyethylene film (PE film) was laminated via an adhesive. At this time, the PE film was not bonded to the bare surface. The obtained resin-coated metal plate is bent and the bare surfaces are overlapped (overlap width: 7 mm), PE
The free end of the film was bent in a direction away from the overlap portion, and the overlap portion was seam-welded according to a conventional method. The free end of the PE film was extended over the weld, locally heated to 180 ° C. and welded to the weld and its vicinity, and the bottom wall was attached in a conventional manner to obtain a 5 gallon weld can.

<Evaluation Test of Corrosion Resistance of Welded Can> A 10% sulfuric acid aqueous solution was stored in the welded can obtained by the above method, and left standing at room temperature to conduct an evaluation test of corrosion resistance. Even when the welding can was left for 30 days or more, no change was observed on the surface in contact with the aqueous solution, and it was confirmed that the welded portion and the repaired portion in the vicinity thereof exhibited excellent corrosion resistance similarly to other portions. Was.

Comparative Example In the example described in the examples, a PE film having the same width as that of the modified PE film and having no free end was laminated via an adhesive. The metal plate was bent so that the bare surfaces overlapped with each other, the overlapped portion (lap width: 7 mm) was seam-welded according to a conventional method, and the bottom wall was attached according to a conventional method to obtain a 5-gallon weld can. An epoxy powder coating was applied and repaired on the welded portion and its vicinity without resin coating. A 10% sulfuric acid aqueous solution was accommodated in the obtained welding can in the same manner as in the example, and left standing at normal temperature to conduct an evaluation test of corrosion resistance. As a result of observation at the time when 30 days had passed, formation of point-like corrosion was observed in the welded portion and the repaired portion in the vicinity thereof.

[0026]

The present invention has the following particularly advantageous effects, and its industrial value is extremely large. 1. In the thermoplastic resin-coated metal plate according to the present invention, bare surfaces are formed at both ends in the width direction of the metal plate, and an insulating coating is not disposed on this portion, so that the welding operation is extremely simple. 2. When the thermoplastic resin-coated metal sheet according to the present invention is repaired in the vicinity of a welded portion after welding to both ends in the width direction of the metal sheet, the thermoplastic resin film (C) having a width larger than the width of the metal sheet.
The work is very simple since the free end of the wire may be extended over the weld and locally heated and welded. 3. The thermoplastic resin-coated metal sheet according to the present invention has excellent corrosion resistance because the thermoplastic resin film is composed of two sheets, and the vicinity of the welded portion is covered and thermally welded by the free end of the thermoplastic resin film (C). The product is obtained.

[Brief description of the drawings]

FIG. 1 is an end view of an example of a thermoplastic resin-coated metal plate according to the present invention.

FIG. 2 is an enlarged cross-sectional view showing a step of welding the ends of a thermoplastic resin-coated metal plate to each other.

FIG. 3 is an enlarged sectional view near a welded portion.

[Explanation of symbols]

 1: metal plate 2: thermoplastic resin film (B) 3: thermoplastic resin film (C) 4: bare surface portion 5: free end of thermoplastic resin film (C) 6: electrode 7: welded portion 8: repaired portion

Claims (2)

[Claims] At least one side of a long metal plate (A) has a width of 10 to 50 at both ends in the width direction of the metal plate (A).
The thermoplastic resin film (B) is covered except for a bare surface portion of mm, and further extends on the thermoplastic resin film (B) by 3 to 30 mm outside both ends in the width direction of the metal plate (A). A thermoplastic resin-coated metal plate, which is coated with a wide thermoplastic resin film (C). 2. The thermoplastic resin film (C) is adhered to the surface of the thermoplastic resin film (B), but the metal plate (A)
2. The thermoplastic resin-coated metal plate according to claim 1, wherein the metal plate is not bonded to the bare surfaces at both ends in the width direction.