JP3153055B2 - Method of manufacturing resin-laminated metal easy-opening lid material excellent in feather property - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is applied to a metal plate such as a steel plate or an aluminum plate, or a surface-treated metal plate obtained by applying a surface treatment film such as tin plating, a chromate film or coating and a resin laminate to such a metal plate. Cutting guide for easy cans
The present invention relates to a method for manufacturing an easily openable lid material provided with a groove .

[0002]

2. Description of the Related Art Easy-open cans (easy-open cans) used for beverage cans, general food cans, and the like, have a handle for tearing off a part or all of an opening piece of a container lid with a handle. The tear-off type that separates from the
There is Lee Ontabu formula. The easy-open can was made of a painted aluminum plate or steel plate as a material for opening the can, punched into a basic lid shape, placed on a flat lower mold, and provided a scored blade with a pointed cross section protruding in an open contour shape. By pressing the upper mold, an opening-shaped cutting guide groove was formed in the material. In order to facilitate the opening of the can, the cutting guide groove should be formed to 1/2 to 2 /
It was necessary to press the score processing blade to reach about 3. However, if the depth of the cutting guide groove was too shallow, the opening property was poor, and if it was too deep, the strength was insufficient and the can was opened by a small external impact. There were transportation problems.

[0003] The material for can opening is becoming extremely thin due to the requirement of openability and the like, and the score processing tool is required to have considerable accuracy.
As disclosed in Japanese Patent Application Laid-Open No. 434/1979 and Japanese Patent Application Laid-Open No. Sho 57-175034, a thin upward connecting piece is formed between the periphery of the opening piece and the can body, and then the opening piece is pressed down to form the connecting piece. , From the middle of which can be bent to form a cutting guide groove. In addition, the surface treatment film layer is cut by the processing of the cutting guide groove and repair coating is applied to prevent the occurrence of rust in the part where the metal surface is exposed, and the repair coating is also used for commercialization. Similar to the operation, a complicated baking process has to be performed for a long time, and there is a problem that the global environment is polluted by carbon dioxide discharged from a solvent mixed with the paint at the time of baking.

[0004] Due to the advantages of workability, corrosion resistance, retention of the content taste and price, aluminum and steel sheets coated with a vinyl chloride organosol of vinyl chloride paint are widely used for easily openable lids. ing. However, on the other hand, in the resource recycling technology, used can bodies are collected and incinerated or redissolved from vinyl chloride paint.
There was a problem of generating toxic dioxins. Due to this problem, research and development of a new paint that replaces the vinyl chloride paint is also in progress.

Recently, to solve the above problems, and the purpose of not repair coating to the cutting guide groove, and pressing process the polyester resin laminated metal sheet of the upper and lower molds at the shoulder radii to form a cutting guide groove Manufacturing techniques for easily openable lids have been developed. However, the easily-openable lid has a problem that many feathers are generated. Feathering refers to an organic film remaining on the cut end of the can body when the easy-opening lid is opened, and is disliked because it gives an unsafe image in appearance. Even if a cutting guide groove is formed on a conventional easy-opening lid, that is, a painted metal plate with a scored blade having a pointed cross section, a problem may occur when the can is opened.

[0006]

SUMMARY OF THE INVENTION As described above, the present invention provides a service life problem of a score processing tool, an environmental problem in a process of producing a coating material, and a feather caused by an easily openable lid coating material which has been widely used to date. it be those that provide an easy open cans of cover material that the purpose of solving the problems, such as sexual problems and has as its gist the thickness on one or both surfaces of a metal plate or surface treated metal sheet of 1:10 A can opening material laminated with a crystalline saturated polyester resin having 100 μ, elongation: 300% or more, crystallinity: 10% or less, and heat of crystal fusion: 10 joules / g or more, having a shoulder radius of 0.1 to 1 A cutting guide groove having a remaining thickness of 1/2 or less of the material thickness is formed using upper and lower molds of 0.0 mm.
After molding by pressing, the crystalline saturated polyester-based resin layer around the cutting guide groove is heat-treated at a temperature from the cold crystallization start temperature of the resin to a temperature lower than the melting point. This is a method for producing a can lid material.

Hereinafter, the present invention will be described in detail.
The material used in the present invention is Sn, Cr, Ni, A on one or both sides of a commonly used metal plate or steel plate.
A surface-treated metal plate provided with one or more plating layers of a corrosion-resistant metal such as L and Zn, and a chromate treatment film is used. Specifically, in addition to a steel plate or an aluminum plate, a tin-plated steel plate obtained by subjecting a Sn plating layer having a coating amount of 0.5 to 3.0 g / m ² to a chemical conversion treatment, a coating amount of 0.3 to 2.0 g
/ ^M nickel-plated steel sheet subjected to chemical conversion treatment is subjected to Ni plating ^2, coating weight 0.01 to 0.5 g / ^{m 2} of Me Ni
Coating layer, and an adhesion amount of 0.5 to 2.0 g / m ² .
Sn / Ni plated steel sheet subjected to a chemical conversion treatment is subjected to Sn plating, usually TFS subjected to metal Cr layer 50~200 ^m g / m ² to Cr oxide layer ^{5~30 m g / m 2 (Tin} Fr
ee Steel L) and the like.

[0008] Naturally, the Cr oxide layer of the aluminum plate is subjected to electrolytic chromic acid treatment or immersion chromate treatment chromium coating weight 10 to 3~50 ^m g / m ² and the metal Cr layer
200 ^m g / m ² applied the surface treated metal plates can also be used. Further, various conditions such as the thickness of these materials are not particularly limited, but the thickness is 0.150 to 0.300 mm and the elongation is 10 to 10 from the adaptability as a lid material.
40% is preferred.

On one or both sides of the above-mentioned metal plate or surface-treated metal plate, the thickness is 10 to 100 μm and the elongation is 3
A crystalline saturated polyester resin film having a crystallinity of 10 or more and a crystallinity of 10 or less and a heat of crystal fusion of 10 joules / g or more is laminated. This resin film has a predetermined shoulder radius
When processing the opening guide groove by pressing with upper and lower molds,
Follows the substrate with good adhesion and the film itself has excellent workability
This allows the substrate to be completely covered even after processing,
It eliminates the need for repair painting that has been necessary since then. Also the opening
By performing a predetermined heat treatment after forming the guide groove,
Easy opening without causing feather problem when opening
Lids can be manufactured .

The crystalline saturated polyester resin layer used in the present invention is a linear thermoplastic polyester obtained by polycondensation of a dicarboxylic acid and a diol, and is represented by polyethylene terephthalate. As the dicarboxylic acid component, terephthalic acid, isophthalic acid, phthalic acid, adipic acid, sebacic acid, azelaic acid, 2,6-
Naphthalenedicarboxylic acid, decanedicarboxylic acid, dodecanecarboxylic acid, cyclohexanedicarboxylic acid, etc. alone or as a mixture, and diol components such as ethylene glycol, butanediol, decanediol, hexanediol, cyclohexanediol, neopentyl glycol, etc. It is. Copolymers of two or more dicarboxylic acid components and diol components, and copolymers of monomers and polymers other than diethylene glycol, triethylene glycol, and the like may be used. In addition, these resins may contain plasticizers, antioxidants,
Additives such as heat stabilizers, inorganic particles, pigments, and organic lubricants may be blended.

However, the crystalline saturated polyester resin layer used in the present invention has the following restrictions for the purpose of the present invention. Resin film thickness 10-1
The reason for limiting the thickness to 00μ is that a thin film having a thickness of less than 10μ does not ensure the barrier properties (corrosion resistance and rust resistance) of the resin film layer, and therefore needs to be made thicker, whereas an excessive thickness exceeding 100μ requires a barrier effect. Has reached the saturation region and is economically problematic. Therefore, considering performance and economy,
The thickness of the resin layer is desirably in the range of 16 to 60 μm.
Further, it is preferred that the elongation at break is 300% or more and the elongation is easy under severe processing conditions, and it is important that the crystallinity is 10% or less. If the elongation at break is less than 300% and the degree of crystallinity exceeds 10%, a large number of defects will be generated in the resin film due to insufficient elongation with respect to the molding of a thin portion at the time of pressing described later.
The elongation is preferably 450% or more. In the present invention, the elongation of the laminated resin film is measured by a method according to JIS C2318 after peeling the resin film from the substrate.

The crystallinity of the present invention is a value measured by the following procedure. (1) X-ray diffraction intensity of the resin layer is 2θ = 5 to 40
Measure within the range. (2) The X-ray diffraction intensity curves at 2θ = 10 and 2θ = 35 are connected by a straight line to be a baseline. (3) A sample which is considered to be almost completely amorphous is obtained by, for example, pouring the same resin as the resin layer into liquid nitrogen after melting, and measuring the X-ray diffraction intensity of the sample under the same conditions as (1). (4) The base of the crystal diffraction peak of the diffraction intensity line obtained in (1) is connected by a smooth curve. The shape of the curve should be similar to the diffraction intensity curve of the amorphous sample measured in (3). (5) The area of the portion surrounded by the baseline of (2) and the curve of (4) is Ia, and the area of the portion surrounded by the diffraction intensity curve of (1) is Ic. (6) Let {Ic / Ia + Ic} × 100 be the crystallized skin.

Further, it is important that the heat of crystal fusion of the laminated resin film used in the present invention is 10 joules / g or more. From the knowledge of the inventors so far, in the easily openable lid obtained by pressing described later, at least the resin film on the inner and outer surfaces of the can around the cutting guide groove has a crystallinity of 20% or more and an elongation of 100% or less. Otherwise, a feathering problem will occur when opening the can. That is, when the can is opened by tearing or pushing the opening piece, when the degree of crystallinity of the resin film around the cutting guide groove is less than 20% or more than 100%, broken pieces of the film are conspicuous at the cut portion, and the appearance is improved. Gives discomfort.

Regarding the workability in the press working, the resin film needs to have low crystallinity and high elongation. On the other hand, with respect to feathering, high crystallinity and low elongation are required, and both contradict each other. Therefore, in the present invention, before pressing, a coating having a low degree of crystallinity and high elongation, after pressing, at least heating and cooling crystallization of the resin coating physical properties of the inner and outer surfaces of the can around the cutting guide groove. This contradiction was resolved by changing to a higher crystallinity and lower elongation.

That is, as a result of various studies, the present inventors have found that a polyester resin film having physical properties of elongation at break of 300% or more and crystallinity of 10% or less is efficiently heated to a crystallinity of 20% or more. In order to make the elongation 100% or less, it was found that a heat of crystal fusion of 10 joules / g or more was required as a physical property of the resin film.

In the present invention, the heat of crystal fusion of a resin refers to a sample obtained by heating a resin in advance to the melting point of the resin + 30 ° C., holding and melting the resin for 5 minutes, and then cooling the resin to a temperature lower than 30 ° C. at a rate of 10 ° C./min. As 10 on a differential scanning calorimeter (DSC).
The size (area) of the peak indicating the melting of the crystal was measured at a heating rate of ° C./min, and the heat of crystal fusion (ΔHf). This heat of crystal fusion is expressed in joules / g, and a large value indicates that the resin has strong crystallinity. Here, the melting point means a temperature at which the endothermic amount of an endothermic peak indicating crystal melting obtained by measuring at a heating rate of 10 ° C./min with a differential scanning calorimeter (DSC) has a maximum value.

The material for opening cans on which the resin film is laminated as described above is processed as follows. Forming of opening guide groove
Easy openability without breaking the resin film
The opening guide groove that ensures the cutting guide that forms the opening piece shape
Using a mold having a shoulder radius of the groove forming upper and lower molds of 0.1 to 1.0 mm , the resin laminated material is pressed and formed, and the metal thickness of the thinnest part is 1 / th of the metal thickness before processing. It is formed thinly to 2 or less.

If the radius of the shoulder radius of the upper and lower die for forming the cutting guide groove is smaller than 0.1 mm, the portion of the shoulder radius is sharp, so that the laminated resin film of the material to be processed is scratched or broken during processing. Further, when pressing is performed with a shoulder radius exceeding 1.0 mm, the material is pressed in an unnecessarily wide part, and the adhesion between the metal and the resin is deteriorated.
The formation of a poor adhesion portion more than necessary causes feathering. Further, the poor adhesion portion of the coating film is not preferable from the viewpoint of corrosion resistance. The peripheral edge of the opening is pressed between the upper and lower dies so as to reach a desired thickness, and the thinnest metal thickness is １ ／ of the metal thickness before processing from the openability.
Hereinafter, it is more desirable to reduce it to 1/3 or less.

Further, in the present invention, after forming the cutting guide groove, the temperature of the resin film around the cutting guide groove during the lid step or the can making step is set to a temperature lower than the temperature at which the resin film starts to crystallize at the cold crystallization temperature. Heat treatment. As described above, in order for the resin film of the laminate material to follow the pressing process, a film having a low crystallinity and a high elongation property, that is, a crystallinity of 10% or less and an elongation of 300% or more is required. On the other hand, in order to improve the feather property when opening the can,
It is necessary that the film characteristics have a crystallinity of 20% or more and an elongation of 100% or less.

Therefore, in the present invention, heat treatment is performed to secure these properties. The heat treatment temperature is the lower limit of the cold crystallization start temperature of the resin film in order to efficiently crystallize the film, and the melting point temperature is the upper limit in order to prevent poor appearance due to melt flow of the resin film and thermal deterioration of the resin film. . These heat treatment conditions must be selected for each thermoplastic resin to be used, since the cold crystallization starting temperature and the melting point differ depending on the thermoplastic resin used. These are measured with a differential scanning calorimeter (DSC) at a heating rate of 10 ° C./min for the thermoplastic resin film, and the cold crystallization onset temperature is determined as the rise of the cold crystallization peak. Where the melting point is the peak temperature of the crystal melting.

The heating method is not particularly limited. Examples of the heating method include heating in a heating furnace, heating by blowing hot air, heating directly under a burner, infrared heating, and heating a substrate from a metal plate by induction heating. A method of bringing a heated solid into contact is exemplified. In particular, in the case of a heat treatment in the middle of the lid making process, it is desirable to heat only the periphery of the cutting guide groove in consideration of the workability of the resin film thereafter.

In these series of processing steps, the resin film having the above-mentioned properties is uniformly stretched together with the substrate, and no processing defects are generated. Therefore, there is no need for repair coating after processing, and good corrosion resistance is ensured. Can be. Further, according to the method of the present invention, since the processing is based on press working such as extrusion or push-back by a shoulder radius portion having a smooth curved surface that is convex to each other, the tool life seen in the pressing method of the sharp blade is reduced. There are no problems, and excellent productivity is guaranteed. Furthermore, by performing a heat treatment after forming the cutting guide groove, it becomes possible to produce an easily openable lid having excellent feathering properties.

Further, the present invention is characterized mainly by optimizing a cutting guide groove present at a peripheral portion of the opening piece, and a tear-off system in which the handle and the opening piece are separated from the can body, and a handle and a handle are provided. It is possible to apply to both the stay-on tub system, in which both the opening pieces remain fixed to the can body even after the can is opened. Hereinafter, examples of the present invention will be described.

[0024]

【Example】

Example 1 thickness 0.250 mm, on the surface of the thin steel sheet hardness 62 (H _R30-T), were subjected to electric tin plating coating weight 2.8 g / m ^2. After tin is heated and melted to obtain a surface having a specular gloss, an electrolytic post-treatment is carried out in a treatment bath mainly composed of chromic acid, and metallic chromium 12 mg / m ² and a hydrated chromium oxide 12 mg / m 2 A chromate film having ² (as Cr) was formed. After washing with water and drying, the steel sheet is heated to obtain a two-layer polyester resin having a different melting point. The upper layer has a thickness of 35 μm and the lower layer has a thickness of 5 μm. The lower layer resin has a lower melting point than the upper layer resin and contains the ionomer. A 40μ resin film was laminated on both sides of the steel sheet. The crystallinity of the laminated film was 4%. The elongation of the film measured by peeling after lamination was 450%. Further, the heat of crystal fusion of the resin film was 28 joules / g, the cold crystallization onset temperature was 110 ° C, and the melting point was 230 ° C.

When a steel plate having a polyester resin film on both sides is formed into an easy-open can lid (3) as shown in FIG. 1, the shoulder radius corresponds to the shape and size of the opening piece as shown in FIG. A part corresponding to the opening piece (2) was extruded upward by pressing a main part of the lid body with a press using upper and lower molds A (5) and (6) each having a thickness of 0.5 mm. At this time, the connecting piece (7) connecting the opening piece (2) and the lid body (1) was processed so as to form a thin portion having a gradual change in plate thickness by pressing.

[0026] Then, as shown in FIG. 3, in a continuous piece (7)
Lower mold B (11) having convex part (13) corresponding to the central part
The lid body (1) is placed on the top, and the concave portion corresponding to the convex portion (13)
It pressed with the upper metal mold | die B (10) which has a groove (12) . By this operation, the continuous piece (7) having a gradual change in the plate thickness
Is bent downward in a V-shape from a substantially middle portion and protrudes into the concave groove (8). Thus, a thin cutting guide line (4) having a V-shaped cross section is formed at the periphery of the opening piece (2) on the lower surface of the lid body (1).

The easy-open can lid thus formed was heat-treated at 130 ° C. for 2 minutes in a heating furnace. The thickness of the steel plate at the thinnest part in this example was 48 μ. The resin film was formed in the same manner as the steel plate, and the film thickness remaining on the surface of the thinnest portion was about 8 μm on both surfaces. The crystallinity of the resin film after the heat treatment was 26%, and the elongation was 87%. The easy-open can lid after this heat treatment was subjected to an evaluation of the openability by measuring the tearing force of the opening piece, and to an energization test for examining the degree of destruction of the resin film on the inner and outer surfaces of the can. Can openability (force to pull handle and tear off opening piece) is 1.7
kg or less, the energization value of the resin film is 0.2 m on the inner side
A, 0.4 mA on the outer surface side was satisfactory enough for practical use. Further, there was no visually noticeable feather around the cut end of the broken cutting guide groove.

EXAMPLE 2 The surface of an aluminum plate made of a 5182 alloy H39 having a thickness of 0.280 mm was subjected to an electrolytic post-treatment in a treatment bath mainly composed of chromic acid to form metallic chromium of 12 mg / m ² and an upper layer thereof. A chromate film having a hydrated chromium oxide of 12 mg / m ² (as Cr) was formed. After washing and drying, the aluminum plate is heated, and a two-layer polyester resin having different melting points, the upper layer contains an ionomer having a thickness of 10 μm, the lower layer has a lower melting point than the upper layer resin having a thickness of 3 μm, and has a total thickness of 13 μm. Resin films were laminated on both sides of the aluminum plate. The crystallinity of the laminated film was 8%, and the heat of crystal fusion was 13 joules / g. The elongation of the film measured by peeling after lamination was 320%, the cold crystallization start temperature was 115 ° C, and the melting point was 225 ° C.

The upper and lower molds A (5) having a shoulder radius of 0.2 mm were prepared by using an aluminum plate having a resin film on both sides.
The same processing as in Example 1 was performed using (6). In the present embodiment, the thickness of the aluminum plate at the thinnest portion was adjusted to be 95 μm. The resin film was formed in the same manner as the aluminum plate, and the film thickness remaining on the surface of the thinnest portion was about 7 μm. The easy-open can lid made by the above-mentioned lid-making process was heat-treated at 205 ° C. for 20 seconds at a coating temperature of 205 ° C. by infrared heating after being wound around the can body. The crystallinity of the resin film after the heat treatment was 32%, and the elongation was 55%. 1.7kg openability
The can was opened without any problem below, and the current value of the resin film was 0.3 mA on the inner surface and 0.2 mA on the outer surface, which was sufficiently satisfactory for practical use. Further, there was no visually noticeable feather around the cut end of the broken cutting guide groove.

Example 3 A 37 μm thick polyester resin film was laminated on the same plated steel sheet as in Example 1 on both sides of the steel sheet via a thermosetting polyester adhesive. The total thickness of the resin film is 4
It was 0μ. The crystallinity of the laminated film was 5%, and the heat of crystal fusion was 11 joules / g. The elongation of the film measured by peeling after lamination was 370%, the cold crystallization onset temperature was 105 ° C, and the melting point was 235 ° C. As shown in FIG. 2, the steel plate having the resin film on both sides is pressed by using upper and lower molds A (5) and (6) having a shoulder radius of 0.8 mm to form an opening piece (2). Was extruded upward. At this time, the peripheral portion of the opening piece (2), the lid body (1), and the connecting piece (7) were processed so as to form a thin portion having a gentle change in plate thickness by pressing.

[0031] Then, as shown in FIG. 5, among the communicating piece (7)
Lower mold having projections (13) on the side and outside portions
The upper die C having the concave portion (17) corresponding to the convex portion (13) of the lower die C ( 15), with the lid body (1) placed on the lower die C (15) in a state of the downwardly expanding inclination. Pressed in (14). By this operation, beads are formed inside and outside the cutting guide groove, and the lid body (1) and the opening piece (2) are removed except for the bead portion.
Became the same height. A thin cutting guide line (4) is formed around the periphery of the opening piece (2) on the upper surface of the main body (1). Thereafter, the vicinity of the cutting guide line was heat-treated by infrared rays at a resin film temperature of 170 ° C. for 1 minute, and was rivet-formed.

In the present embodiment, the thickness of the steel plate at the thinnest portion was adjusted to 55 μm. The resin film is formed in the same manner as the steel plate, and the film thickness remaining on the surface of the thinnest part is about 6 on both sides.
μ. The crystallinity of the resin film after heat treatment is 26%,
The elongation was 70%. The easy-open can lid after the heat treatment was subjected to an evaluation of can-opening property by measuring the pulling force of the opening piece and an electric current test for examining the degree of destruction of the resin film on the inner and outer surfaces of the can. The can openability was 1.8 kg or less, and the can was opened without any problem. The energization value of the resin film was 0.3 mA on the inner surface and 0.3 mA on the outer surface, which was sufficiently satisfactory for practical use. Further, there was no visually noticeable feather around the cut end of the broken cutting guide groove.

Comparative Example 1 A two-layer polyester resin having a different melting point was formed on the same plated steel sheet as in Example 1, the upper layer was 20 μm in thickness, the lower layer was 20 μm in thickness, and the lower layer resin had a lower melting point than the upper layer resin. Was laminated on both sides of the steel sheet. The crystallinity of the laminated film is 4
%, And the heat of crystal fusion was 28 joules / g. Also,
The elongation of the film measured by peeling after lamination was 450%, the cold crystallization onset temperature was 110 ° C, and the melting point was 230 ° C. A steel sheet having a resin film on both sides is provided with a shoulder radius of 0.
Using the upper and lower molds A (5) and (6) of 08 mm, the same processing and heat treatment as in Example 1 were performed. In the present embodiment, the thickness of the steel plate at the thinnest portion was adjusted to be 48μ. The crystallinity of the resin film after the heat treatment was 26%, and the elongation was 87%. The can openability was 1.7 kg or less and the can was opened without any problem. However, the current value of the resin film was 105 mA on the inner surface and 95 mA on the outer surface.
It showed a very large value of mA, and many defects were observed in the resin film of the cutting guide portion. Even if the shoulder radius was too small, a practically usable one could not be obtained.

Comparative Example 2 On the same plated steel sheet as in Example 1, a two-layer polyester resin having a different melting point, the upper layer having a thickness of 20 μm, the lower layer having a thickness of 20 μm, and the lower resin having a lower melting point than the upper resin was an ionomer. Was laminated on both sides of the steel sheet. The crystallinity of the laminated film is 4
%Met. The elongation of the film measured by peeling after lamination was 450%, the cold crystallization starting temperature was 110 ° C, the melting point was 230 ° C, and the heat of crystal fusion was 28 Joules / g.
A steel plate having a resin film on both sides, with a shoulder radius of 1.2 m
The same processing and heat treatment as in Example 1 were performed using the upper and lower molds A (5) and (6) of m. In the present embodiment, the thickness of the steel plate at the thinnest portion was adjusted to be 48μ. The resin film was formed in the same manner as the steel plate, and the film thickness remaining on the surface of the thinnest portion was about 8 μm. The crystallinity of the resin film after heat treatment is 26
% And elongation was 875%. The can openability was excellent at 1.8 kg or less, and the current value of the resin film was 1.2 mA on the inner surface and 1.4 mA on the outer surface. The remaining film was severe, giving an unpleasant appearance, and there was a problem in practicality even if the shoulder radius was too large.

Comparative Example 3 An 8 μm-thick polyester resin film was laminated on both sides of the steel sheet on the same plated steel sheet as in Example 1. The crystallinity of the laminated film was 4%. The elongation of the film measured by peeling after lamination was 310%, the temperature at which cold crystallization started was 110 ° C., the melting point was 230 ° C., and the heat of crystal fusion was 28 Joules / g. This steel sheet having a resin film on both sides was subjected to the same processing and heat treatment as in Example 1 using the same mold as in Example 1. In the present embodiment, the thickness of the steel plate at the thinnest portion was adjusted to be 48μ. The crystallinity of the resin film after the heat treatment was 26%, and the elongation was 60%. The can openability is 1.8kg or less and the can is opened without any problem. The energization value of the resin film is very large at 102.8mA on the inner surface and 112.9mA on the outer surface. Occurrence was observed, and it could not be used practically.

Comparative Example 4 On the same plated steel sheet as in Example 1, a two-layer polyester resin having a different melting point, the upper layer having a thickness of 20 μm,
The lower layer has a lower melting point than the upper layer resin with a thickness of 20μ, and the total thickness is 40
μ resin film was laminated on both sides of the steel sheet. The crystallinity of the laminated film was 4%. The elongation of the film measured after peeling after lamination was 280%, the cold crystallization starting temperature was 110 ° C, the melting point was 230 ° C, and the heat of crystal fusion was 28 Joules / g. This steel sheet having a resin film on both sides was subjected to the same processing and heat treatment as in Example 1 using the same mold as in Example 1. In this comparative example, the thickness of the steel plate at the thinnest portion was adjusted to be 50 μm. The resin film was formed in the same manner as the steel plate, and the film thickness remaining on the surface of the thinnest portion was about 8 μm. The crystallinity of the resin film after the heat treatment was 26%, and the elongation was 60%. The can openability was 1.8 kg or less, and the can was opened without any problem. However, the current value of the film was 54 mA on the inner surface and 6 mA on the outer surface.
It showed 8 mA and there were considerable defects in the coating, which was cut off for practicality.

Comparative Example 5 A two-layer polyester resin having a different melting point and the upper layer having a thickness of 20 μm was formed on the same plated steel sheet as in Example 1,
The lower layer has a lower melting point than the upper layer resin with a thickness of 20μ, and the total thickness is 40
μ resin film was laminated on both sides of the steel sheet. The crystallinity of the laminated film was 12%. The elongation of the film measured by peeling after lamination was 310%, the cold crystallization start temperature was 115 ° C, the melting point was 230 ° C, and the heat of crystal fusion was 28 Joules / g. The same steel plate having a resin film on both sides was processed in the same manner as in Example 1 using the same mold as in Example 1. In this embodiment, the thickness of the steel plate at the thinnest portion is 50 μm.
It was adjusted to become. The crystallinity of the resin film after the heat treatment was 28%, and the elongation was 75%. 1.7kg openability
The can is opened without any problem below.
The value was very large at 04.8 mA and 98.9 mA on the outer surface side, and many defects were observed in the resin film of the cutting guide portion, and it was not practically usable.

COMPARATIVE EXAMPLE 6 A two-layer polyester resin having a different melting point and the upper layer having a thickness of 20 μm was formed on the same plated steel sheet as in Example 1.
The lower layer has a lower melting point than the upper layer resin with a thickness of 20μ, and the total thickness is 40
μ resin film was laminated on both sides of the steel sheet. The crystallinity of the laminated film was 4%. The elongation of the film measured by peeling after lamination was 320%. further,
The cold crystallization start temperature was 110 ° C., the melting point was 230 ° C., and the heat of crystal fusion of the resin film was 8 joules / g. This steel sheet having a resin film on both sides was subjected to the same processing and heat treatment as in Example 1 using the same mold as in Example 1. In this comparative example, the thickness of the steel plate at the thinnest portion was adjusted to be 48 μm. The resin film was formed in the same manner as the steel plate, and the film thickness remaining on the surface of the thinnest portion was about 7 μm. The crystallinity of the resin film after the heat treatment was 15%, and the elongation was 140%. The can openability was 1.8 kg or less, and the can was opened without any problems. The current value of the coating was 0.2 mA on both the inner and outer surfaces, which was a level that was not a problem in practical use. The remaining film was severe, giving an unpleasant appearance, and there was a problem in practicality.

Comparative Example 7 The same processing as in Example 1 was performed on the same laminated steel sheet as in Example 1 using the same mold as in Example 1, and the coating temperature was set to 90 ° C. in a heating furnace. Heat treatment was performed for 10 minutes. In this comparative example, the thickness of the steel plate at the thinnest portion was adjusted to be 48 μm. The resin film was formed in the same manner as the steel plate, and the film thickness remaining on the surface of the thinnest portion was about 8 μm. The crystallinity of the resin film after the heat treatment was 8%, and the elongation was 310%.
The can openability was 1.8 kg or less, and the can was opened without any problem. The energization value of the film was 0.3 mA on both the inner and outer surfaces, which was a level that was not a problem for practical use. The remaining film was severe, giving an unpleasant appearance, and there was a problem in practicality.

Comparative Example 8 The same processing as in Example 1 was performed on the same laminated steel sheet as in Example 1 using the same mold as in Example 1, and the coating temperature was adjusted to 250 ° C. by hot air heating. Heat treatment was performed for 10 seconds. In this comparative example, the thickness of the steel plate at the thinnest portion was 48 μm.
It was adjusted to become. The resin film was formed in the same manner as the steel plate, and the film thickness remaining on the surface of the thinnest portion was about 12 μm.
35% crystallinity and 50% elongation of resin film after heat treatment
Met. The can openability was 1.8 kg or less, and the can was opened without any problem. However, the portion heated by the hot air turned yellow, and there was a problem in practicality.

[0041]

As described above, the method for manufacturing an easily-openable lid according to the present invention uses a material obtained by laminating a resin film on a steel plate or aluminum and presses the thin portion by pressing without using a sharp blade. By adopting the method of forming the cutting guide groove by the forming method, there is no need to perform any painting in the manufacturing process, and the major problems of the prior art, such as the problem of the tool life of the machining tool and the uneasiness of the corrosion resistance, etc. It can be completely eliminated. Furthermore, by performing a heat treatment after the forming process of the cutting guide groove, it becomes possible to produce an easy-open can lid having a good feather property. In particular,
If the steel easy-open can lid is put into practical use, it will be possible to provide a product suitable for recycling in response to recent global environmental problems by making it a "monometal can". Naturally, the steel sheet itself is excellent in economic efficiency, and it is expected that by using steel plates for both the can body and the can lid, the product will be more economical and easy to reuse as resources.

[Brief description of the drawings]

FIG. 1 is a perspective view of a can lid having a tear-opening piece formed according to the present invention;

FIG. 2 is a longitudinal sectional view showing the procedure of the present invention in the order of steps,

FIG. 3 is a longitudinal sectional view showing the procedure of the present invention in the order of steps;

FIG. 4 is a longitudinal sectional view showing the procedure of the present invention in the order of steps;

FIG. 5 is a longitudinal sectional view showing a state where beads are formed on both sides of a cutting guide groove;

FIG. 6 is a sectional view of a cutting guide groove having a V-shaped cross section by a conventional sharp blade pressing method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 lid body 2 opening piece 3 easy-open lid 4 cutting guide line 5 upper mold A 6 lower mold A 7 connecting piece 8 upper mold R part 9 lower mold R part 10 upper mold B 11 lower mold B 12 concave groove 13 convex part 14 upper die C 15 lower die C 16 bead 17 concave part

Continuation of the front page (56) References JP-A-61-279324 (JP, A) JP-A-2-86433 (JP, A) JP-A-6-122438 (JP, A) JP-A-57-175034 (JP) , A) JP-B 3-60735 (JP, B2) JP-B 3-67454 (JP, B2) JP-B 56-5606 (JP, B2) (58) Fields surveyed (Int. Cl. ⁷ , DB) Name) B21D 51/44

Claims (1)

(57) [Claims] 1. A metal plate or a surface-treated metal plate having a thickness of 10 to 100 μm, an elongation of 300% or more, a crystallinity of 10% or less, and a heat of crystal fusion of 10 joules / g or more on one surface or both surfaces. the material for can opening laminated with saturated polyester resin, cut proposed below half the remaining thickness of the material thickness using the upper and lower molds of Katamarumi radius 0.1~1.0mm
After the inner groove is formed by pressing process, the feathers of which is characterized in that heat treatment of the crystalline saturated polyester resin layer of the cutting guide groove periphery at a temperature less than the cold crystallization onset temperature above the melting point of the resin Manufacturing method of excellent resin-laminated metal easy-opening lid material.