JPH0262093B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a can for packaging seafood, and more specifically, the can body is made of a steel plate substrate, and the lid material is made of an aluminum alloy material. Concerning cans for packaging seafood. (Prior Art and its Problems) Conventionally, so-called easy-open lidded containers have been widely used as cans that can be easily opened by hand without using any special equipment. This can lid uses an aluminum sheet as the metal material from the viewpoint of workability, and the can lid made of this aluminum plate is provided with a score that reaches halfway in the thickness direction of the aluminum plate to partition the opening part. A rivet is formed in the cover plate itself on the opening part, and the pull tab is fixed with the rivet, and is used by being double-sealed between it and the flange of the can body member. Although this easy-open lid can provide satisfactory results for less corrosive contents such as beer and carbonated beverages, it is not suitable for seafood containing salt such as table salt due to the corrosion of the aluminum material. There is a problem. For this reason, in conventionally known seafood cans, an organic protective coating is applied to the inner surface of the aluminum lid material, and in order to correct the scratches on the coating that occur during score processing and rib processing. Correction painting is performed using spray painting, electrodeposition painting, etc. However, the above-mentioned correction coating is complicated and costly, and its protective effect is not necessarily satisfactory. In particular, for packaging seafood, tinplate and tin-nickel steel plates are widely used as can body members from an economic standpoint. When canning seafood with a tightly wrapped lid, a battery is formed due to contact between dissimilar metals, and corrosion of the aluminum material occurs significantly. (Object of the Invention) Therefore, the present invention provides a can for seafood cans that provides excellent pitting corrosion resistance without the need to correct the organic protective coating applied to the aluminum easy-to-open lid. be. (Structure of the Invention) According to the present invention, in a method for producing seafood, which comprises tightening an easy-open lid made of internally coated aluminum to an internally coated steel can body, the internally coated steel can body is immersed in 1% saline solution. Uses an internally coated steel can body with an enamellator value (ERV) of 4 mA or less when measured at an applied voltage of 6.3 volts, and the internally coated aluminum easy-open lid is not subjected to correction coating during the lid and can manufacturing processes. Provided is a method for producing a seafood can, characterized by an easy-to-open lid made of coated aluminum. (Function) In a fish and shellfish can consisting of an inner-coated steel can body and an inner-coated aluminum easy-open lid, surprisingly, the inner coating has a large effect on the pitting corrosion of the easy-open lid. It is the degree of exposure of the steel material of a steel can body, and is an internally coated steel can body whose enamelator value (ERV) measured at an applied voltage of 6.3 volts in 1% saline is 4 mA or less, especially 1 mA or less. The discovery that pitting corrosion of aluminum lids can be prevented even when using internally coated aluminum easy-open lids that are not subjected to correction coating during the lid making and can manufacturing processes. It is based on The attached drawings Figures 1 to 3 show the area ratios of aluminum material and steel material as 1:1, 9.6:1, and 1:1.
9.6, mix the stuffed fish and 3% sodium chloride solution at a ratio of 1:10, heat and cool the solution, and calculate the galvanic couple current flowing between the two materials and the potential difference with respect to the silver-silver chloride reference electrode. The measured results are shown. According to this result, Al is electrochemically less noble than Fe, and therefore, in both systems, corrosion current flows due to the elution of Al into the electrolyte, but this current increases as the area of Al increases. However, it can be seen that it increases as the exposed area of Fe increases. The present invention applies this principle to the combination of an internally coated steel can body and an internally coated aluminum easy-open lid. If a can is used, a 6-month actual can storage test at 37°C (this corresponds to 1 to 1.5 years of storage at room temperature) shows that the aluminum in the scored or riveted parts of the easy-opening lid was It has been discovered that pitting corrosion can be prevented. In the present invention, a steel plate substrate material is used as the can body member, but the degree of metal exposure of the can body is
It is important that the inner surface is coated so that the current is 4mA or less. That is, when a steel plate substrate material is used as the can body and an aluminum material is used as the material, since a battery is formed by connecting dissimilar metals, corrosion of the aluminum material tends to occur significantly. According to the present invention, the inner surface of the can body, which is made of a steel plate substrate material, is coated so that the degree of metal exposure is 4 mA or less, thereby reducing the tendency of aluminum materials to corrode due to the formation of such batteries. effectively suppressed. (Preferred embodiments of the invention) The present invention will be described in detail below based on specific examples shown in the accompanying drawings. Structure of Seafood Can In FIG. 4 showing an example of the seafood can of the present invention, this specific example is a two-piece can, including a seamless can body A with an opening at the top and a seam-fastened part at the top of the can body. and an easy-open lid B that is fastened. Can body A is made of painted steel material, and has a cylindrical body made thin by drawing and ironing.
It consists of a bottom part that is not thinned and is seamlessly connected to the body part. The easy-open lid is made of painted aluminum and has the structure shown in FIGS. 6 and 7. Can Body In FIG. 5, which shows an enlarged sectional view of the can body, the can body consists of a steel plate substrate 20, a protective coating 21 provided on the inner surface of the container, and a printing layer 33 applied to the outer surface if necessary. (a) Steel plate substrate 20; In the present invention, as the steel plate substrate 20, a steel plate substrate known per se such as a nickel-tin plated steel plate of stain-free steel (TFS), a black plate, a tin plated steel plate, etc. is used. The thickness of the steel plate substrate 20 is generally 0.12 to 0.40.
mm, particularly preferably in the range of 0.14 to 0.36 mm. If this thickness is lower than the above range,
Deformation may occur during manufacture or storage of the case, and on the other hand, if it exceeds the above range, processing such as double seaming tends to become difficult. (b) Protective coating film 21; Further, in the present invention, the inner surface of the can of the steel plate substrate 20 is coated to form the protective coating film 21 so that the degree of metal exposure is 4 mA or less, particularly 1 mA or less. Ru. The current value representing the degree of metal exposure is measured by the so-called enamellator method (using 1% saline). If this current value is larger than the above range, it is not possible to effectively prevent the formation of a battery due to the connection of dissimilar metals.
It becomes difficult to effectively prevent corrosion of the casing. As the protective paint for forming the protective coating film 21, a paint having excellent workability and adhesion, such as an epoxy-phenol paint, is used. As the above-mentioned epoxy-phenol paint, any paint can be used as long as it contains an epoxy resin component (a) and a resol type phenol-formaldehyde resin component (b). As the epoxy resin component (a), all those conventionally used as epoxy resin components in so-called phenol-epoxy paints can be used without restriction, but representative examples include epihalohydrin and bisphenol A. [2,2'-
Bis(4-hydroxyphenyl)propane] produced by condensation with an average molecular weight of 800 to
5500, particularly preferably 1400 to 5500 epoxy resins, which are preferably used for the purpose of the present invention. This epoxy resin has the following general formula: In the formula, R is a condensed residue of 2,2'-bis(4-hydroxyphenyl)propane, and n is a number selected such that the average molecular weight of the resin is 800 to 5500. . The molecular weight of the epoxy resin mentioned above is the average molecular weight, and therefore, the epoxy resin for paints with a relatively low degree of polymerization and the linear epoxy resin with a high molecular weight, that is, the phenoxy resin, have an average molecular weight within the above range. There is no problem in using them in combination so that As the phenol/aldehyde resin component (b) used in combination with the epoxy resin component (a), any resin can be used as long as it contains a polycyclic phenol in its resin skeleton. As used herein, polycyclic phenol refers to phenols having multiple rings to which phenolic hydroxyl groups are bonded, and representative examples of such polycyclic phenols include the formula Divalent phenols represented by the following are known, where R represents a direct bond or a divalent bridging group,
Such phenols are preferably used for the purposes of the present invention. In the divalent phenol of the formula (), the divalent bridging group R is represented by the formula -CR ¹ R ² -
an alkylidene ^group , -O- ^,
-S-, -SO-, -SO ₂ -, -NR ³ - (in the formula, R ³
is a hydrogen atom or an alkyl group having 4 or less carbon atoms, etc., but an alkylidene group or an ether group is generally preferred. Suitable examples of such divalent phenols (a) are 2,2'-bis(4-hydroxyphenyl)propane (bisphenol A), 2,2'-bis(4-hydroxyphenyl)butane (bisphenol A), and 2,2'-bis(4-hydroxyphenyl)butane (bisphenol A). Phenol B) 1,1'-bis(4-hydroxyphenyl)ethane Bis(4-hydroxyphenyl)methane (bisphenol F) 4-hydroxyphenyl ether, p-(4-hydroxy)phenol, etc. However, bisphenol A and bisphenol B are most preferred. These polycyclic phenols, alone or in combination with other phenols, are subjected to a condensation reaction with formaldehyde to form a resol type phenol aldehyde resin. As for other phenols, all monohydric phenols conventionally used in the production of this type of resin can be used, but in general, the following formula is used: In the formula, R ⁴ is a hydrogen atom, an alkyl group or an alkoxy group having 4 or less carbon atoms, and 3
Two of R ⁴ are hydrogen atoms and one is an alkyl group or an alkoxy group, and R ⁵
is a hydrogen atom or an alkyl group having 4 or less carbon atoms, a difunctional phenol represented by, for example o-
Cresol, p-cresol, p-tertbutylphenol, p-ethylphenol, 2,3-
Most preferred is one or a combination of two or more difunctional phenols such as xylenol and 2,5-xylenol. Of course, in addition to the bifunctional phenol of the above formula (), phenol (carbolic acid), m
-cresol, m-ethylphenol, 3,5
-trifunctional phenols such as xylenol and m-methoxyphenol; monofunctional phenols such as 2,4-xylenol and 2,6-xylenol; p-tert aluminum phenol, p-nonylphenol, p-phenylphenol ,p-
Other difunctional phenols, such as cyclohexylphenol, alone or in combination with the difunctionality of formula () above, can also be used in the preparation of phenolic aldehyde resins. The resol type phenol aldehyde resin used in the present invention is obtained by reacting the above-mentioned phenol and aldehyde in the presence of a basic catalyst. There is no particular restriction on the amount of aldehyde to be used with respect to phenol, and it can be used in the ratio conventionally used in the production of resol type resins, for example, a ratio of 1 mol or more, particularly 1.5 to 3.0 mol, per 1 mol of phenol. aldehydes can be suitably used, but there is no particular disadvantage in using less than 1 mol of aldehydes. It is generally desirable to carry out the condensation in a suitable reaction medium, especially an aqueous medium. As the basic catalyst, any of the basic catalysts conventionally used in the production of resol type resins can be used, and among them, ammonia, magnesium hydroxide, calcium hydroxide, barium hydroxide, calcium oxide, and basic catalysts can be used. Hydroxides, oxides, or basic salts of alkaline earth metals such as magnesium carbonate, basic magnesium chloride, and basic magnesium acetate are preferably used. These basic catalysts may be present in the reaction medium in catalytic amounts, especially in amounts of 0.01 to 0.5 mol %. Condensation conditions are not particularly limited, and generally heating may be performed at a temperature of 80 to 130°C for about 1 to 10 hours. The resulting resin can be purified by means known per se, for example by extracting and separating the resin component of the reaction product from the reaction medium with, for example, a ketone, alcohol, hydrocarbon solvent or a mixture thereof;
If necessary, unreacted substances are removed by washing with water, and water is further removed by an azeotropic method or a sedimentation method.
It can be a resol type phenolic aldehyde resin that can be mixed with an epoxy resin. The above-mentioned epoxy resin component (a) and phenolaldehyde resin component (b) can be used in combination in any ratio, and there are no particular restrictions. However, when the present invention is applied to a metal-painted adhesive can, the protective coating film 21 also serves as an adhesive intervening layer (primer), so (a):(b)=95:5 to 50:50, especially It is desirable to use a combination of both at a weight ratio of 90:10 to 60:40. In the present invention, the epoxy resin and phenolic resin are mixed in a dissolved state in ketones, esters, alcohols, hydrocarbon solvents, or mixed solvents thereof, and used directly as a coating material for the adhesive intervening layer. However, it is generally desirable to precondense these mixed resin solutions at a temperature of 80 to 130° C. for about 1 to 10 hours, and then prepare the coating for the adhesive primer layer. Furthermore, instead of using the epoxy resin and the phenolaldehyde resin in the form of a two-component paint, the phenolaldehyde resin may be treated with known modifiers such as fatty acids, fatty acids, After modification with one or more of polymerized fatty acids, resin acids (or rosins), drying oils, alkyd resins, etc., it is combined with an epoxy resin, or both resins are optionally mixed with vinyl acetal (butyral) resin, Of course, it can also be modified with a modifier such as an amino resin, xylene resin, acrylic resin, or phosphoric acid. The protective coating film 21 made of the paint as described above is
As already mentioned above, in order to suppress the degree of metal exposure of the steel plate substrate 20 to 4 mA or less,
It is provided with a thickness of 14 μm, in particular 6 to 12 μm.
If the film thickness is smaller than this range, it will be difficult to suppress the degree of metal exposure to 10 mA or less, and if the film thickness is larger than the above range, workability will tend to decrease. . (C) Can body In the present invention, the above-mentioned can body member is a three-piece can body with adhesive (nylon adhesive) joints or welded joints on the side surfaces, and drawing and ironing, deep drawing, and impact processing. It is applied as a seamless can body formed by extrusion processing etc. This can body has a flange portion and an easy-open lid 1, as shown in FIGS. 6 and 7, which will be described later.
and the sealing groove 3, and the groove 3 is first seamed around the flange using a primary seaming die. Next, in a secondary seaming step, this flange portion is further seamed by 90 degrees along the side wall of the can body to form a seafood can. Structure of the Can Lid In FIG. 6 (top view) and FIG. 7 (side sectional view) showing the structure of the easy-open lid used in the present invention, the easy-open lid 1 is fitted onto the inner surface of the side surface of the can body. A sealing groove 3 is provided on the outer circumferential side of an annular rim portion (chuck wall) 2 to be opened, and a score 5 is provided inside the annular rim portion 2 to define a portion 4 to be opened. A rivet 6 formed by protruding the lid material toward the outer surface of the can lid is formed in this portion to be opened, and an opening pull tab 7 is fixed as shown below by riveting the rivet 6. That is, the unsealing pull tab 7 has an unsealing tip 8 at one end and a gripping ring 9 at the other end, and a fulcrum portion 10 fixed with a rivet 6 is present adjacent to the unsealing tip 8. The pull tab 7 is provided so that its opening tip 8 is close to the opening start portion of the score 5. The aforementioned sealing groove 3 is lined with a sealing rubber composition (sealant) 11 to provide a seal between the can body flange and the can body flange. As shown in FIG. 8, this easy-open lid is made up of an aluminum base 30, an inner protective coating 31 applied to the inner surface of the can, and an outer protective coating 32 applied to the outer surface of the can. It is completed. The score 5 is carved so as to reach halfway in the thickness direction of the aluminum base 30 from the outer surface of the can. Of the inner surface protective coating 31 of the lid, in the part where the score 5 is provided and the part where the rivet 6 is provided,
The paint film is often damaged during processing, but
According to the present invention, this portion is used for manufacturing seafood cans without applying a correction coating (reveal coating). Easy-open lid All aluminum materials used for this type of easy-open lid can be used, such as pure aluminum or aluminum with other alloying metals, especially aluminum containing small amounts of magnesium, manganese, etc. Alloys are used. Ordinary aluminum materials are electrochemically more base than steel, and when both metals coexist in an electrolyte system, corrosion of aluminum progresses. From this point of view, in the present invention, Cu0~
0.8%, Mg0~2.8%, Mn0~1.5%, Fe0~0.5%,
Aluminum alloy containing 0 to 0.5% Si (% is based on weight) or using this aluminum alloy as a core material, aluminum purity
Corrosion in the above system can be effectively prevented by using a clad plate made of 99.7% or more pure aluminum. That is, from the viewpoint of corrosion resistance, it is preferable that Cu contained as an alloy component be in the range of 0% to 0.8%, particularly 0.2 to 0.8%. This Cu acts to bring the aluminum material into an electrochemically noble state, and corrosion of the steel-aluminum system is more effectively prevented. In addition, in the case of clad plates, the core material is in a more noble state than the surface pure aluminum, so the pure aluminum layer sacrificially dissolves, protecting the core material, and when the core material comes into contact with liquid due to corrosion, the core material is more noble than the surface pure aluminum. Corrosion of materials is effectively prevented. Furthermore, Cu acts to improve mechanical strength. Further, Mg is preferably 0% to 2.8% from the viewpoint of corrosion resistance. If it exceeds 2.8%, pitting corrosion tends to occur when combined with steel. Mn is preferably 0% to 1.5% from the viewpoint of processability. If it exceeds 15%, processing such as riveting becomes difficult. The thickness of the aluminum material varies depending on the size of the lid, etc., but it is generally 0.20 to 0.50 mm, especially 0.23 mm.
It is preferably within the range of 0.30mm to 0.30mm. From the viewpoint of adhesion of the inner material to the aluminum material and corrosion resistance, it is generally desirable to form a chromate treatment film or a phosphate alumite treatment film on the surface of the aluminum material. The chromate treatment film can be formed by a method known per se, for example, after degreasing the aluminum material with caustic soda and slightly etching it, CrO ₃ 4
g/, H ₃ PO ₄ 12 g/, F 0.65 g/, and the rest is carried out by chemical treatment by immersion in a treatment liquid such as water. The thickness of the chromate treatment film is
5 to 50 mg/dm ² , expressed in weight of Cr atoms;
In particular, from the viewpoint of adhesion, it is desirable that the content be within the range of 10 to 35 mg/dm ² . In addition, as a means of forming a phosphoric acid alumite treatment film, for example, aluminum material is degreased with caustic soda, washed with water, and then electrolyzed in a phosphoric acid solution (concentration 10 to 50 wt%) using aluminum as an anode (voltage 20 to 40 V, current density 10
~30A/ ^dm2 ) Form an anodic oxide film. Adhesion is determined by the thickness of the film being within the range of 0.1 to 2 μm.
It is preferable from the viewpoint of workability. As an internal protective coating for this aluminum material,
The thermosetting or thermoplastic protective coating mentioned above in the section of the can body is used. Even if the degree of metal exposure (ERV) of the aluminum lid is large, pitting leakage will not occur in the present invention, but there is a problem of expansion can formation due to hydrogen generation. It is necessary to use a paint that has good processability so that the defects in the coating film are not too large. An example of such a paint with good processability is a vinyl chloride resin organosol paint, in which a vinyl chloride paste resin is added to a solution phase of a solvent-soluble vinyl chloride copolymer resin and an epoxy-containing thermosetting paint resin. It is made by dispersing resin particles. In this case, by using a high molecular weight vinyl chloride resin particle, for example, one with an average degree of polymerization of 1500 or more, toughness that can withstand processing can be obtained, and by using an epoxy-phenol type resin as a thermosetting resin. , excellent adhesion to aluminum materials can be obtained, and further, by containing an epoxy plasticizer, workability can be improved by plasticization. Another type of paint that is easy to process is epoxy.
It is a phenolic paint, and excellent processability can be obtained by using an epoxy resin with a particularly high molecular weight, for example, one with an average molecular weight of 25,000 to 35,000. The thickness of the inner coating film is 3 to 12 μm, especially 5 to 12 μm.
A range of 10 μm is appropriate. In addition, a lid laminated with a plastic film such as one made of an epoxy/phenolic adhesive primer and a PET film can also be used. According to the present invention, a can for seafood is manufactured by tightening the above-mentioned easy-open lid to the can body. It is important to prevent corrosion of the seamed parts. To this end, a sealing rubber composition 11 such as styrene-butadiene rubber is prepared as shown in FIG.
The coating is applied up to at least the base of the chuck wall 10 of the lid, preferably up to 1/5 of the height of the chuck wall 10, to prevent damage to the can body coating near the seaming part. (Effects of the Invention) According to the present invention, even when using a combination of an inner-coated steel can body and an inner-coated aluminum easy-open lid, the easy-open lid is suppressed by suppressing metal exposure on the can body. Pitting corrosion of this lid could be prevented without the need for corrective coating of the inner surface coating. In addition, by using aluminum as the material for the easy-open lid of seafood cans, the opening force is reduced and easy opening is achieved, and cuts to fingers etc. caused by the cut edges of the score section are prevented. By preventing metal elution, especially iron elution, the flavor retention of the contents could also be maintained at a high level. Furthermore, since there is no need for correction coating in the lid making process or the can production process, the number of processes is reduced, which provides the manufacturing advantage of reducing equipment costs and manufacturing costs, as well as reducing the occurrence of feathering due to the correction coating. It has now become possible to resolve the issue. Example 1 Toyo Seam Can A TFS material (plate thickness 0.17 mm) with metallic chromium and hydrated chromium oxide on the surface is used as the can body, and epoxy/phenol paint is applied to the inside and outside surfaces. After painting the inner side with a base coat (thickness 3μm) and then a top coat (thickness 3μm),
Through processes such as cutting and gluing nylon for side seams, a body maker makes the can body for the T2 can. Next, flanging is performed on both ends of the can body. The aluminum lid is made of commercially available Al-Mg alloy 5052 material (thickness 0.30 mm) treated with chromic acid phosphoric acid.
On the inside of the lid, one type is a vinyl chloride organosol paint (film thickness 10μm), and the other type is a PET film (16μm) coated with an epoxyphenol primer after laminating with an epoxyphenol resin.
All exterior surfaces will be painted with epoxy urea paint. After that, wax is applied to the surface and cut into a predetermined size. Next, it is punched out using a press to the size of a 307-diameter lid, curled, and coated with sealing compound. After that, score processing and tab attachment are performed to create an easy-open lid. The can body and aluminum lid produced in this manner are wrapped with a seamer to form an empty pack can. Table 1 shows the metal exposure (ERV) of the can body and lid at this time and the results of packing the boiled tuna and storing it at room temperature for one year. Example 2 Tin-nickel steel plate welded can A commercially available tin-nickel steel plate (plate thickness
Apply epoxy/phenol paint to the inner and outer surfaces using 0.19 mm, tin plating amount of 0.8 g/m ² , nickel plating amount of 20 mg/m ² ). The inner surface is coated with a base coat (thickness: 4μm), then top coat (thickness: 4μm).
4μm) and then cut to the size for the T2 can body. After that, a can body is made using a welding machine, and correction paint is applied to the inner and outer surfaces of the welded parts. Next, flanging is performed on both ends of the can body. This can body is combined with the aluminum lid described in Example 1 to form an empty pack can. Table 1 shows the results of the metal exposure (ERV) of the can body and lid and the boiled tuna. Example 3 Welded can with aluminum lid using clad plate The can body was manufactured in the same manner as in Example 2, and the aluminum lid was manufactured in the same manner as in Example 1 using clad material. The core material components of the clad plate at this time were Si0.1%,
Fe0.3%, Mn0.9%, Mg1.0%, Cu0.4% others
The skin material is made of 99.7% pure aluminum and is clad to a thickness of 10% of the board thickness. Table 1 shows the results of the metal exposure (ERV) of the can body and lid and the boiled tuna. The corrosion depth of the 5052 material was up to 70% of the plate thickness, but the corrosion of the clad material stopped at the pure aluminum layer on the surface. Comparative Example 1 Solder Can A tin plate (tin adhesion amount: 2.8 g/m ² , plate thickness: 19 mm) is used as the can body, and an epoxy phenol paint (film thickness: 3 μm) is applied to the inner surface. Apply a finishing varnish to the outside. After cutting to the size of the T2 can body, solder it with a body maker to make the can body, and apply correction paint to the inside and outside surfaces of the soldered part. Next, flanges are made on both ends of the can body. The aluminum lid was the same as that described in Example 1, but the lid was laminated with PET film on the inside. Table 1 shows the results of the metal exposure (ERV) of the can body and lid and the boiled tuna. Comparative Example 2 A welded tin can with an aluminum lid wrapped around a clad plate. Tin plate (tin adhesion amount: 2.8 g/m ² , plate thickness: 0.19 mm) is used as the can body, and epoxy/phenol paint is applied to the inner surface. (3μm film thickness). Apply a finishing varnish to the outside. After cutting the can body to the size of the T2 can body, use a welding machine to fabricate the can body, and apply correction paint to the inside and outside surfaces of the welded part. Next, flanging is performed on both ends of the can body. The aluminum lid was the same as that described in Example 3, but only the inner PET lid was used to make an empty pack can. Can body and exposed metal (ERV) at this time
Table 1 shows the results of packing boiled bluefin tuna. When there was a large amount of exposed metal in the can body, perforations were also observed in the clad plate. 【table】

[Brief explanation of the drawing]

Figures 1, 2, and 3 show the results of measuring the galvanic couple current and the potential difference with respect to the silver-silver chloride reference electrode when a steel material and an aluminum material are immersed in an electrolyte solution with different area ratios. FIG. 4 is a perspective view showing an example of the seafood can of the present invention, FIG. 5 is a cross-sectional view showing an enlarged cross-sectional structure of the steel can body, and FIG. is a top view of the easy-open lid used in the present invention, FIG. 7 is a side sectional view of the easy-open lid shown in FIG. 6, and FIG. 8 is an enlarged sectional view showing the cross-sectional structure of the easy-open lid. It is. 1 is the easy-open lid, 3 is the sealing groove, 4 is the part that should be opened, 5 is the score, 6 is the rivet, 7
20 shows the opening tab, 20 shows the steel plate substrate, and 21 shows the inner surface protective coating film.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a seafood can, which comprises tightening an easy-open lid made of internally coated aluminum to an internally coated steel can body, wherein the internally coated steel can body is made of 6.3 volts in 1% saline solution. An internally coated steel can body with an enamel rating (ERV) of 4 mA or less measured by applied voltage is used, and the internally coated aluminum easy-open lid is not coated with correction coating during the lid making process or the can making process. A method for manufacturing a seafood can, characterized by an easy-to-open lid.