JP2526725B2 - Method for manufacturing coated thin can - Google Patents

Description

The present invention relates to a method for producing a coated thin can,
More specifically, the present invention relates to a method for producing a coated thin-walled can, which can be economically thinned by simple production and can form a protective layer having excellent strength and durability.

[Prior Art] Side-seamless (sand seamless) cans are made of a metal material such as an aluminum plate, a tin plate, or a tin-free steel plate at least 1 between the drawing die and the punch.
Subjected to step drawing, formed into a cup composed of a sideless seamless body and a bottom integrally connected to the body seamlessly, and then bent and extended at the curvature corner of the redrawing die, It is manufactured by thinning the side wall. Side-side seamless cans are often used because they have a relatively small number of manufacturing steps and can achieve a thin can body.

Further, as a method for coating the organic material of the side seamless can, in addition to a method of applying an organic paint to a can after molding which is generally widely used, a method of previously laminating a resin film on a metal material before molding, etc. It is known and as an example of this latter case, Japanese Patent Publication No. 59-34580 discloses that a metal material laminated with a polyester film derived from terephthalic acid and tetramethylene glycol is used. It is also known to use a coated metal plate of vinyl organosol, epoxy, phenylix, polyester, acrylic or the like when manufacturing a redraw can by bending and stretching.

[Problems to be Solved by the Invention] However, in the production of conventional side wall thinned coating cans, applying an organic coating material after molding complicates the process, and requires a sufficient thickness to form a protective layer. It becomes a layer and is poor in economic efficiency in mass production. Further, conventionally, a molded can obtained by previously laminating an organic coating material on a metal plate has durability, barrier property, and
There is a problem that the strength and the like are extremely lowered. That is, the organic coating layer is thinned when the side wall portion is thinned, but its strength, barrier property, etc. tend to decrease as the thickness decreases. For this reason, in the production of seamless cans, the strength and barrier properties of the protective layer corresponding to the reduction in wall thickness pose problems.

Further, in the can manufacturing process, there are a cleaning process, drainage process, exhaust treatment process, etc., and various types of equipment are required. However, in the can manufacturing process, it is desired to shorten the time and omit the steps as much as possible. However, the conventional method for manufacturing a painted can and the method for manufacturing a laminated can have a problem because a washing step and a draining step are required in the manufacturing process.

Further, the organic coating layer is susceptible to damage by the processing tool, and the damaged portion of such coating causes an apparent or potential metal exposure, resulting in metal elution and corrosion from this portion. Also, in the production of seamless cans, plastic flow occurs in which the size increases in the height direction of the can and the size decreases in the circumferential direction of the can. During this plastic flow, the metal surface and the organic coating are separated. There is a tendency that the adhesive strength of the both decreases and the adhesive strength of both decreases with time due to residual strain in the organic coating. Such a tendency becomes particularly remarkable when the contents for canning are hot-filled or the cans are heat-sterilized at low to high temperatures.

Therefore, an object of the present invention is to produce a coated deep-drawing can by drawing or deep-drawing an organic coated metal plate,
The resin layer and metal layer can be made thinner, and the durability of the can,
Another object of the present invention is to provide a method for producing a coated thin-walled can in which corrosion resistance and heat resistance are sufficiently achieved.

Another object of the present invention is to produce a coated deep-drawn can,
It is an object of the present invention to provide a manufacturing method capable of omitting the manufacturing process and shortening the manufacturing time.

[Means for Solving Problems] According to the present invention, an oriented thermoplastic resin film is laminated on a metal plate to be treated, and a high temperature volatile lubricant is applied to the laminated metal plate, followed by punching, The processed metal plate is formed into a cup shape by drawing, and the drawn thermoplastic resin film layer of the cup-shaped container is bent and stretched under heating while being molecularly oriented, and re-drawing is performed. Heat treatment is performed to relax the internal stress of the stretched oriented thermoplastic resin film layer, to perform oriented crystallization, and to volatilize the lubricant. Then, the heat treated cup is subjected to edging, printing, baking, and edging to coat a thin can. A method for manufacturing a can is provided.

In the method for producing a can of the present invention, an adhesive primer layer is interposed between the metal plate to be treated and the oriented thermoplastic resin film to laminate the film on the metal plate, and the adhesive primer is cured if necessary. May be.

[Function] The present invention uses an oriented thermoplastic resin film as an organic coating material of a laminated metal material for processing, and increases the crystallinity and the degree of orientation during redrawing. It is based on the knowledge that, by processing under the drawing conditions of 1, the economical thinning can be achieved in deep drawing cans and the coating material can form a protective layer having excellent strength and durability. Is.

In the present invention, it is important that the organic coating material of the metal plate to be treated is an oriented thermoplastic resin film.

Using a material obtained by laminating an organic coating material composed of an oriented thermoplastic resin film on a metal plate, and performing redrawing and heat setting under the specific conditions described later, the molecular orientation and crystallinity of the organic coating are obtained. Can be sufficiently improved. In order to laminate the resin film, it can be obtained by appropriately selecting the composition of the resin and the molecular weight, and the temperature and the cooling rate of the lamination.

In the present invention, the laminated metal sheet is coated with a lubricant having a high temperature volatility, preferably a lubricant having a high temperature volatility of 70% or more, particularly preferably 80% or more, and punched, particularly punched by heating, drawing. The metal plate is processed into a cup shape. The lubricant, which is rich in volatility, protects the organic coating layer from tools during punching and drawing, stretching,
While the coating layer follows the shrinking metal surface, it is sufficiently volatilized and removed by high temperature heating after redrawing. Therefore, it is possible to eliminate the steps such as washing used in the conventional method.

In the present invention, it is important that the obtained cup-shaped container is cup-heated, bent and stretched while molecular orientation is given to the organic coating material. In the present invention, by heating the cup-shaped container under a specific condition, bending and stretching and then redrawing, while further increasing the orientation degree of the organic coating resin described above, it is possible to suppress the influence of a shock line in the drawing and redrawing process. You can The degree of orientation in this case is 20%
It is desirable to increase the above. Such a treatment method is effective in increasing the degree of orientation of the organic coating resin, and also increases the crystallinity to some extent.

Next, it is important that the obtained re-drawing cup-shaped container is heat-treated to enhance the internal stress of the organic coating material and the oriented crystallinity of the organic coating material, and accelerate the volatilization of the lubricant. That is, it is important that the heat treatment of the cup-shaped container is performed under the temperature condition of changing the characteristics of the organic coating material and promoting the volatilization of the lubricant having the high temperature volatility. Although the internal stress of the organic coating material reaches a maximum in the final stage of redrawing, the removal of the stress improves the durability and processing adhesion of the organic coating film as a protective coating material.

The oriented crystallinity of the organic coating resin is preferably in the range of 10 to 70%. Increasing the degree of orientation and crystallinity as described above increases heat resistance, strength, and barrier properties, and can be an excellent protective coating material even if it is thin. In this case, the thickness of the organic coating layer of the molding can is 5 to 20μ.
Even when m is set, it has excellent heat resistance, strength, and barrier properties, as will be seen in Examples described later.

Further, as described above, since a lubricant having a high temperature volatility, particularly a lubricant having a high temperature volatility of 70% or more and having a high volatility is used, such a lubricant has the above-mentioned conditions. It facilitates the combination of heat treatments.

Such a heat-treated cup-shaped container is subjected to processing such as edging, printing, baking, squeezing, or edging, if necessary, and formed into a can. Therefore, the coated thin-walled can thus obtained is not a conventional complicated method for manufacturing a thin-walled can, and is capable of coating as excellent as an organic coating material for a thick-walled coated can. Such a configuration is excellent in a deep-drawn can.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for producing a coated thin can according to the present invention will be described in detail.

Lamination of Organic Coating Material to Metal Plate Laminating method in the present invention is carried out by heat fusion method, dry lamination, extrusion coating method of oriented thermoplastic resin film on surface-treated metal plate, and heat treatment is particularly preferable. A fusion method can be used. Further, when the adhesiveness between the coating resin and the metal plate is poor, an adhesive agent or the like may intervene in addition to the primer paint.

FIG. 1 is an example of a structural sectional view of a laminate according to the present invention. As shown in FIG. 1, a laminated body 10 of an organic coating material and a metal plate is provided with a metal substrate 12 and a heat containing an inorganic pigment on the outer surface side thereof through an adhesive primer or an adhesive agent 14 if necessary. It comprises an outer surface layer 16 of a plastic resin and an inner surface layer 18 of an oriented thermoplastic resin provided on the inner surface side thereof with an adhesive primer or adhesive layer 14 interposed therebetween. These thermoplastic resins 16 and 18 may be molecularly oriented and thermally fixed in a crystallized state to some extent, and may be firmly adhered to the metal base 12.

In addition, in laminating such metal plates,
The degree of orientation / crystallinity is adjusted to be suitable for the subsequent processing. The thickness of the coating resin layer is generally 3 to 50 μm, especially 5
It is desirable to be in the range of 40 μm. In the case of heat fusion using a film, it may be unstretched or stretched.

In the present invention, various surface-treated steel plates and light metals such as aluminum are used as the metal plate.

As the surface-treated steel sheet, a cold-rolled steel sheet is annealed and then secondary cold-rolled, and one or more surface treatments such as zinc plating, tin plating, nickel plating, electrolytic chromic acid treatment and chromic acid treatment are performed. Can be used. An example of a suitable surface-treated steel sheet is an electrolytic chromic acid-treated steel sheet, which is particularly provided with a metal chromium layer of 10 to 200 mg / m ^{2 and} a chromium oxide layer of 1 to 50 mg / m ² (metal chromium conversion). Yes,
This has an excellent combination of coating film adhesion and corrosion resistance. Another example of the surface-treated steel plate is a hard tin plate having a tin plating amount of 0.5 to 11.2 g / m ² . This tin plate is
Chromic acid treatment or chromic acid / phosphoric acid treatment is preferably performed so that the amount of chromium is 1 to 30 mg / m ^{2 in} terms of metallic chromium.

As still another example, an aluminum-coated steel plate that has been subjected to aluminum plating, aluminum pressure welding, or the like is used.

As the light metal plate, an aluminum alloy plate is used in addition to a so-called pure aluminum plate. Aluminum alloy sheets excellent in corrosion resistance and workability are Mn: 0.2 to 1.5% by weight, Mg: 0.8 to 5% by weight, Zn: 0.25 to 0.3% by weight, and
Cu: 0.15 to 0.25% by weight, with the balance being Al. These light metal plates are also preferably subjected to chromic acid treatment or chromic acid / phosphoric acid treatment so that the chromium amount becomes 20 to 300 mg / m ^{2 in} terms of metal chromium.

The thickness of the metal plate varies depending on the type of metal, the use or size of the container, but it is generally preferable to have a thickness of 0.10 to 0.50 mm. Among them, in the case of surface-treated steel plate, it is 0.10 to 0.30 mm. Thickness, or 0 for light metal plates.
It should have a thickness of 15 to 0.40 mm.

It is important that the oriented thermoplastic resin used for coating the metal plate is capable of molecular orientation, and that the orientation degree and the crystallinity described later can be obtained by redrawing and heat setting.
Examples of the coating resin material used in the present invention include olefin resin films such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic ester copolymer and ionomer; polyethylene. Polyester films such as terephthalate, polybutylene terephthalate, ethylene terephthalate / isophthalate copolymer, ethylene terephthalate / adipate copolymer, ethylene terephthalate / sebacate copolymer, butylene terephthalate / isophthalate copolymer; nylon 6, nylon
Polyamide film such as 6,6, nylon 11, nylon 12; polyvinyl chloride film; polyvinylidene chloride film; poly-P-xylene glycol biscarbonate, poly-dioxydiphenyl-methane carbonate,
Polycarbonate films such as poly-dioxydiophenylethane carbonate, poly-dioxydiphenyl 2,2-propane carbonate, poly-dioxydiphenyl 1,1-ethane carbonate; acrylonitrile-butadiene copolymer with high nitrile content, acrylonitrile −
A high nitrile resin film such as a styrene copolymer: a polystyrene resin film which satisfies the above conditions can be used. In the present invention, all the films of the above resins can be used, but it is preferable to use a film which is composed of polyester mainly composed of ethylene terephthalate units and which is biaxially molecularly oriented. These films may be unstretched or biaxially stretched.

As the adhesion primer, a paint having excellent adhesion to a metal plate and corrosion resistance and also excellent adhesion to a resin film is used. As the adhesive primer, a coating material composed of a combination of an epoxy resin and a curing agent resin for the epoxy resin, such as a phenol resin, an amino resin, an acrylic resin, a vinyl resin, a urea resin, particularly an epoxy-phenol resin or a vinyl chloride resin, Organosol-based paints, which are composed of vinyl chloride copolymer resin and epoxy resin-based paint compositions, are used. The thickness of the adhesive primer or the adhesive layer is preferably in the range of 0.1 to 5 μm, but a thickness that does not disturb the molecular orientation of the crystalline thermoplastic resin is appropriately selected and used.

At the time of lamination, an adhesive primer or an adhesive layer is provided on one or both of a metal plate or a film, dried or partially cured, and then both are pressure-bonded and integrated under heating. The biaxial molecular orientation in the film may be slightly relaxed during the laminating process, but there is no problem in drawing and redrawing, and it may be preferable in terms of molding workability.

The film for the outer surface used in the present invention may contain a filler (pigment) for the purpose of concealing the metal plate and assisting the transmission of the wrinkle holding force to the metal plate during drawing-redrawing.

Inorganic fillers include inorganic white pigments such as rutile-type or anatase-type titanium dioxide, zinc white, and gloss white; barite, precipitated barium sulfate, calcium carbonate, gypsum, precipitated silica, aerosil, tanks, calcined or uncalcined clay. , Barium carbonate, alumina white,
White pigments such as synthetic or natural mica, synthetic calcium silicate and magnesium carbonate; black pigments such as carbon black and magnetite; red pigments such as red iron oxide; yellow pigments such as Siena; and blue pigments such as ultramarine blue and cobalt blue. be able to. These inorganic fillers can be added in an amount of 10 to 500% by weight, particularly 10 to 300% by weight, based on the resin.

Punching Punching-drawing is performed by coating a coated metal plate as shown in FIG.
10 is punched into a disk, and a pre-drawing cup 24 having a bottom portion 20 and a side wall 22 is formed in the pre-drawing process using a pre-drawing punch and a die having a large diameter. In the pre-drawing process and the re-drawing process described later, the coated metal plate 10 is formed by applying a lubricant. Lubricants are rich in high temperature volatility, and it is desirable to select a lubricant whose high temperature volatility satisfies 70% or more, particularly 80% or more. The lubricant in such a range is sufficiently volatilized at the time of heat setting, which will be described later, to facilitate the subsequent processing. Further, it is important to preheat the coated metal plate 10 during processing, and the temperature of the coated metal plate 10 is preferably in the range of not less than the glass transition point (Tg) of the coating resin −30 ° C. and not more than the thermal crystallization temperature. At this heating temperature, the followability of the coating resin to the metal surface is improved, so that breakage of the resin coating layer is prevented.

The lubricant is specifically liquid paraffin, synthetic paraffin,
Edible oil, hydrogenated edible oil, palm oil, various natural waxes, polyethylene wax and the like are used, but various lubricants may be mixed and used within the range of the volatility as described above. The amount applied varies depending on the type, but in general,
The content is preferably in the range of 0.1 to 10 mg / dm ^2, particularly 0.2 to 5 mg / dm ² , and the lubricant is applied by spraying or electrostatically applying it to the surface in a molten state.

Further, the drawing ratio in this drawing process is generally 1.2 to
It is preferably in the range of 1.9, especially 1.3 to 1.8. The aperture ratio is a value defined by the following equation.

formula Re-drawing step Next, the pre-drawing cup 24 is held by an annular holding member and a re-drawing die (not shown) inserted in the cup, coaxially with the holding member and the re-drawing die, and inside the holding member. Removing punch and redrawing die provided so as to be able to move in and out are relatively moved so as to mesh with each other, and redrawing is performed on a deep drawing cup 26 having a smaller diameter than the front drawing cup,
Similarly, it is performed by redrawing into a cup 28 having a smaller diameter and a cup 30 having a smaller diameter. When redrawing
Action of the redrawing die A thin ironing is applied to the coated metal sheet between the redrawing punch and the redrawing die during redrawing so that the coated metal sheet is thinned by bending and stretching at the corners. To reduce the wall thickness.

Further, in the redrawing process, cup heating is performed in the same manner as in the drawing process. It is important that the heating temperature of the squeeze cup is preset within a range from the glass transition temperature of the coating resin to -30 ° C or higher and the thermal crystallization temperature or lower. With this cup heating,
By the bending and stretching process, the coating resin is set to have a molecular orientation.

In coating resin, the degree of uniaxial orientation is In the equation, H1 ° and H2 ° are CuKa lines, and the full width at half maximum of the diffraction intensity distribution curve (Fig. 4) along the Debye-Scherrer ring of the strongest diffraction plane ((010)) measured by the transmission method ( ) Is shown. The measuring position of the coating film corresponding to H1 ° and H2 ° is on the center line of the coating plate in the MD direction, for H1 ° from the center of the can body wall, and for H2 ° from the top of the can.
The area is 10 mm (Fig. 5).

<Sampling of coating film> After removing the outer surface coating of a small piece of metal plate cut out to a size of 40 mm x 40 mm centering on a predetermined measurement position with sandpaper, dissolve the metal with 6N hydrochloric acid and isolate the coating film did.

The orientation degree of the coating resin of the redraw cup is set to 20% or more, particularly 30 to 95%, as evaluated by the average orientation degree defined by

As mentioned above, the redrawing process is performed in multiple steps, and by performing redrawing in multiple steps, the degree of orientation of the coating resin is increased and the side wall is made thinner, so that the entire thickness is uniform. Becomes This is performed according to the state of the cup heating.

FIG. 3 is an explanatory sectional view of a portion where the cup is bent and stretched during each redrawing. In FIG. 3, the front drawing cup 24 formed of a coated metal plate is held by an annular holding member 32 inserted in the cup and a redrawing die 33 located below the holding member 32. A redrawing punch 34 is provided coaxially with the holding member 32 and the redrawing die 33 and so as to be able to move in and out of the holding member 32. Redraw punch 34
And the die 33 are moved relative to each other so as to engage with each other.

As a result, the side wall portion of the front throttle cup 24 is re-throttled from the outer peripheral surface 35 of the annular holding member 32, through the curvature corner portion 36 thereof, and vertically bent radially inward. A deep drawing cup 40 having a diameter smaller than that of the front drawing cup 24 is formed by passing through a portion defined by the upper surface 38 of the die 33 and being bent substantially vertically in the axial direction by the action corner portion 39 of the redrawing die 33.
And the side wall is bent and stretched to reduce the wall thickness.

In the deep drawing process of the present invention, the radius of curvature (RD) of the working corner portion of the redrawing die is set to 1 to 2.9 of the metal plate thickness (tR).
Double and especially 1.5 to 2.9 times the size enables effective bending and stretching.

Further, effective factors for reducing the wall thickness include the back tension and the dynamic friction coefficient (μ) of the annular surface 37 of the holding member 32 and the annular surface 38 of the redrawing die 33, but these should be adjusted within a certain range. Thus, the desired range can be obtained.

The side wall of the can is 55 to 95% of the plate thickness (tb), especially 60 to
It is effective to reduce the thickness to 95%.

The aperture ratio defined by redrawing is And is generally in the range 1.1 to 1.6, especially 1.15 to 1.5.

In the present invention, the heat treatment of the coated deep-drawn cup is performed in a state in which the deformation of the thermoplastic coating resin at the open end of the cup is restrained. In order to restrain the deformation of the thermoplastic resin at the open end, various means can be used depending on the shape of the open end. For example, a method of holding the open end of a straight coated deep-drawing cup without wrinkle holding flat plate portion (cup flange portion), etc. from inside and outside with a pair of molds, or formed during drawing and redrawing. There is a method of using a wrinkle retainer flat plate portion (cup flange portion) and the like integrated with the cup as a deformation restraint portion.

Heat Set Treatment The obtained deep-drawn can is preferably subjected to heat treatment in the state of forming a cup flange, for example. The heat treatment is performed so that the crystallinity of the coating resin is sufficiently promoted and the internal stress generated in the coating resin is relaxed, although it depends on the type of resin.

The volatilization of the lubricant during heating at this time is sufficiently promoted as long as the characteristics in the above range are satisfied. For this reason,
Processes such as cleaning treatment are omitted, and wastewater and exhaust treatment facilities are not required.

Specifically, it is desirable that the heat treatment temperature T satisfies the following formula T ≦ melting point of coating resin −5 ° C. More specifically, for example, in the case of coating a PET film, a temperature of 70 to 240 ° C, particularly 150 to 230 ° C is suitable. The oriented crystallization of the resin by the heat treatment requires a relatively short time at a high temperature and a longer time at a low temperature.

Heat treatment, infrared heating furnace, hot air circulation furnace, flame heating method,
It is performed by any heating means such as a high frequency induction heating method.
Of course, in the present invention, the heat treatment can be performed by baking in a process such as outer surface printing.

The degree of crystallization of the resin after heat setting is measured by the density method, but the following formula is used based on the density measured by the density gradient tube. In the formula, p is the density of the resin sample, pc is the density of the perfect crystalline body of the resin, and pa is the density of the perfect amorphous body of the resin.

And the crystallinity is preferably in the range of 10 to 70%, particularly 15 to 70%.

The cup-shaped container that has been subjected to such heat treatment is formed by being subjected to processing such as edging, printing, baking, squeezing, or edging, if necessary. The molded can has corrosion resistance and heat resistance even though the coating film has a thin thickness of 5 μm to 20 μm.

[Effects of the Invention] As described above, according to the present invention, in the combination of all the steps of the manufacturing method of the coated thin can, the heat setting of the re-drawing can is incorporated as an effective step, that is, the organic coating. By selecting the oriented thermoplastic resin film as the material, the orientation degree is enhanced during redrawing, and the lubricant having a high volatility at high temperature has the following effects. The thin organic coating resin has a sufficiently high degree of crystallinity and orientation during can making, and such an organic coating layer has sufficient strength and barrier properties even if it is a thin layer. Therefore, the coated thin-walled can thus produced has excellent durability and corrosion resistance. In addition, when the can is manufactured, a cleaning process or the like can be partially omitted, and the manufacturing process can be simplified.

[Examples] The present invention will be described in more detail with reference to Examples.

The methods of evaluating and measuring the container characteristics in the examples and comparative examples are as follows.

(A) X-ray orientation degree It is measured by the method described in the text of the specification.

(B) Crystallinity The density of the sample was determined by the density gradient tube method. Thus, the crystallinity was calculated according to the following formula.

p: Measured density (g / cm ³ ) pa: Complete amorphous density (g / cm ³ ) pc: Complete crystalline density (g / cm ³ ) Polyethylene terephthalate system pc = 1.455 (g / cm ³ ) pa = 1.335 ( g / cm ³ ) The sample used was one used for measuring the X-ray orientation, and the crystallinity of the two samples was defined as the crystallinity.

(C) Formability Observation of shock line occurrence Observation of resin coating layer peeling (delamination) Metal exposure (measurement of enamel lator value and ERV) (D) Corrosion resistance Then, store it at 37 ° C for a long time and observe the corrosion state and pitting leakage inside the can.

(E) Heat resistance Observation of damage to the coating layer caused by dint on thinned deep-drawn cans printed and baked (200 ° C, 3 minutes) on the outer surface.

Example 1 An organic coated metal plate was obtained by thermally bonding a 20 μm-thick biaxially oriented polyethylene terephthalate film to the screen of a tin-free steel (TFS) plate having a thickness of 0.18 mm and a tempering degree of DR-9. . A paraffinic lubricant with a volatility of 80% is applied to this coated metal plate, and the surface temperature of the organic coating film is about 80%.
After heating the plate so that the temperature became ℃, it was punched into a disk having a diameter of 187 mm and formed into a shallow-drawing cup according to a conventional method. The drawing ratio in this drawing process is 1.50.

Next, in the first, second, and third redrawing steps, the drawing cup was preheated to 80 ° C., and then redrawing was performed. The molding conditions in the first to third redrawing steps at this time are as follows.

1st redraw ratio; 1.29 2nd redraw ratio; 1.24 3rd redraw ratio; 1.20 redraw die The deep-drawn cup thus redrawn was then bottom domed. The characteristics of the deep-drawn cup are as follows.

Cup diameter 66mm Cup height 140mm Side wall thickness change rate -20% Heat-setting temperature 220 ℃, heat-setting time 2 minutes heat setting is performed with this flanged organic coated deep-drawing cup, then trimming and printing (200 ℃- After baking for 3 minutes), necking and flanging were performed to obtain a can body for two-piece canning.

 The evaluation shown in Table 1 was performed using this can body.

As a result, a coated thin-walled can having a protective layer excellent in strength and durability, which can be economically thinned by a simple manufacturing process.

Comparative Example 1. A deep-drawn can was prepared in the same manner as in Example 1 except that the flange-coated organic-coated deep-drawn cup obtained by redrawing was not heat-set.

As a result, as shown in Table 1, delamination of the coating resin layer occurred in the trimming edge portion in the printing process, and it was unsuitable for the container in terms of processing adhesion, heat resistance and corrosion resistance.

Comparative Example 2. Same as Example 1 except that the plate heating of the organic coated plate before punching and drawing, the preheating of the cup before each redrawing, and the heat setting after redrawing were all eliminated. Created a deep-drawn can.

As a result, as shown in Table 1, a large number of microcracks are generated in the coating resin layer of the shock line portion of the cup during drawing and redrawing, and delamination of the coating resin layer occurs in the trimming edge portion during the printing process. It occurred and was completely unsuitable as a container.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an organic coated metal plate of the present invention, FIG. 2 is a process diagram of a manufacturing method according to the present invention, and FIG. 3 is a diagram for explaining a redrawing method. FIG. 4 shows a typical deep drawn can of the present invention,
FIG. 5 is an X-ray diffraction photograph when a resin film is irradiated with X-rays in a direction perpendicular thereto, and FIG. 5 is a view showing a measurement position of a resin film for measuring the degree of uniaxial orientation of the resin. is there.

Claims (1)

(57) [Claims] 1. A metal plate to be treated is laminated with an oriented thermoplastic resin film, and a high temperature volatile lubricant is applied to the laminated metal plate, which is then punched and drawn to form a cup-shaped metal plate. And, the oriented thermoplastic resin film layer of the cup-shaped container is subjected to bending and redrawing under heating while imparting molecular orientation to the oriented thermoplastic resin film layer, and the re-drawn cup-shaped container is heat-treated to obtain a stretched oriented thermoplastic resin. Inner stress relaxation of the resin film layer, orientation crystallization, volatilization of the lubricant, and rim cutting, printing, baking, and edging the heat-treated cup to form a coated thin can. .