JPH057262B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a case with an easy-to-open lid, and more specifically, the entire lid including the processed part has excellent corrosion resistance, excellent seaming performance (sealing performance), The present invention relates to a case with an easy-to-open lid, which has a combination of easy-to-open and easy-to-open lids. (Prior Art and Technical Problems of the Invention) 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 is
An aluminum plate is used as the metal material from the viewpoint of workability, and a score is provided on the can lid made of this aluminum plate so as to reach the middle of the thickness direction of the aluminum plate to demarcate the opening part. A rivet is formed on the lid plate itself, and the pull tab is fixed with this 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 drinks, it is not suitable for general food can contents.
For example, it was completely impossible to apply this method to contents containing salt because of the corrosion of the aluminum material. Of course,
In order to prevent corrosion of aluminum materials, an organic protective coating is applied to the inner surface of aluminum cans, but it is necessary to avoid significant damage to the coating during scoring and riveting. I don't get it.
In addition, in order to correct the scratches on the paint film, it has been proposed to apply correction coating using electrodeposition coating.
In addition to being cumbersome and expensive to operate, the protective effect is not always satisfactory. In particular, for food cans, tain-free steel (TFS) is used as the can body material, one from the economic standpoint and the other from the standpoint of excellent corrosion resistance and adhesion to paint films. Can bodies made of electrolytic chromic acid-treated steel plates are widely used, but in food cans with aluminum easy-open lids wrapped around TFS can bodies, local batteries are formed by dissimilar metal connections, and the aluminum material Significant corrosion begins to occur. In addition, in order to eliminate the above-mentioned drawbacks, JP-A-48-49590
The publication discloses an easy-open lid using a composite sheet in which a partially crystalline polyolefin resin film is bonded to the inner surface of a metal sheet via an adhesive layer. However, score processing on the composite sheet,
Riveting the pull tab causes distortion in the resin film, which can lead to diaphragm (film separation).
There are also disadvantages such as stress release heat treatment must be performed to remove distortion after the above-mentioned processing, and there is a risk that distortion may occur in the resin film during heat sterilization. (Object of the Invention) Therefore, an object of the present invention is to provide an aluminum case with an easy-to-open lid that eliminates the above-mentioned drawbacks. Another object of the present invention is to provide a case with an easy-to-open lid that has a combination of excellent corrosion resistance of the entire lid including the processed portion, excellent seaming performance, and easy opening. Still another object of the present invention is to provide an inner protective layer with a thermoplastic polyester film that has excellent barrier properties against corrosive components and retains the flavor of the contents, so that the physical properties of the film remain stable even under harsh conditions such as heat sterilization. To provide an easy-to-open lid that maintains its adhesion to an aluminum substrate without substantially degrading it. Still another object of the present invention is that a thermoplastic polyester film inner surface material is in close contact with the inner surface of the aluminum can, and this inner material acts as a continuous barrier against corrosive components. To provide a case with an easy-to-open lid that also functions as an electrical insulation barrier at a seam portion with a body. Still another object of the present invention is to provide a case with an easy-to-open lid, in which the inner surface material protects the lid score portion and the rivet processing portion, and the lid is broken precisely along the score portion when opening. is to provide. (Structure of the Invention) According to the present invention, in the canning case formed by seaming a can body member and an easy-open lid formed of an aluminum material, the easy-open lid is arranged at least on the inner surface of the can. An aluminum base material whose side is chromate-treated, a thermoplastic polyester film inner surface material provided on the side that will become the inner surface of the can, and an epoxy-phenol resin adhesive layer provided on the joint surface of the base body. The easy-open lid is made of a laminate that is stacked on top of each other and bonded under heat and pressure at a temperature above the softening point and below the melting point of the polyester. A case with an easy-to-open lid is provided, characterized in that the can body member and the easy-to-open lid are tightly wound together with a polyester film inner surface material interposed therebetween. Conventional thermoplastic polyester film (PET film) mainly composed of ethylene terephthalate units
Among various plastic films, it is known as a film that has excellent mechanical strength, barrier properties against various components, and heat resistance.
However, using this PET film as the inner material of an easy-open lid with a score
The tensile strength of PET film is about 2 to 10 times higher than that of polyethylene or polypropylene.
In addition, the thermal adhesion is insufficient, and therefore the resin film cannot be sheared according to the score, so it is considered to be extremely difficult, and there are no examples of it actually being used. In the case of an easy-open layer with a score using a film inner surface material, the score is provided only on the metal substrate, and some kind of scratch must be provided on the film surface material so that it can be easily broken. This is completely unacceptable in terms of the corrosion resistance of the metal base of the score part. Thus, the inner film material exists in the form of a completely continuous film, and when the metal substrate is broken at the location of the score, the inner film material is broken at the score location and exactly along the score. is required. The present invention applies a PET film as an inner surface material to an aluminum base material, which has been chromate-treated at least on the inner surface of the can, through an epoxy-phenol resin adhesive layer provided on the bonding surface of the base material. This was based on the truly surprising discovery that when thermocompression bonding is performed at a temperature above the softening point of polyester and below the melting point, the adhesion is improved and the PET film layer breaks easily and according to the score upon opening. It is something that Although the present invention is applicable to all can body members, it can be particularly advantageously applied to surface-treated steel sheets, such as electrolytic chromic acid treated steel sheets, tin-plated steel sheets, and the like. The shape of the can body member may be a can body for a so-called three-piece can that has open ends at the top and bottom and a side seam, or a so-called seamless can body for a so-called two-piece can that has no seams between the sides and the bottom. It may be a can body. In the former case, the seam may be formed by any method such as gluing, welding, or soldering. (Embodiments of the Invention) The present invention will be described in detail below based on specific examples shown in the accompanying drawings. Structure of the Can Lid In FIG. 1 (top view) and FIG. 2 (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 peripheral side of the annular rim portion 2 to be opened, and a score 5 is provided inside the annular rim portion 2 to define a portion 4 to be opened. In this portion to be opened, the lid material is formed to protrude to the outer surface of the can lid, or a rivet 6 is formed, and an opening pull tab 7 is fixed as shown below by riveting the rivet 6. That is, the opening pull tab 7 has a tearing tip 8 at one end and a gripping ring 9 at the other end,
Close to the tearing tip 8 there is a fulcrum section 10 which is fixed with a rivet 6. The pull tab 7 is provided so that its tearing tip 8 is located at the opening start portion of the score 5. In FIG. 3-A showing an enlarged cross-sectional structure of the score portion 5 of this easy-open lid, the easy-open lid 1 of the present invention has an aluminum base 11 and a chromate treatment applied to both surfaces of the aluminum base. There are layers 12a and 12b, and a chromate-treated layer 12a is formed on the side of the base that becomes the inner surface of the container.
Epoxy-phenolic resin adhesive layer 1 through
3 is provided, and an inner surface material 14 of thermoplastic polyester film is provided via this adhesive layer 13. An outer surface protective organic coating film 15 is provided on the side of the aluminum material base that becomes the outer surface of the container via a chromate treatment layer 12b. Score 5 mentioned above
is carved so as to reach the middle of the thickness direction of the aluminum material base 11, but it should be understood that the inner surface material 14 exists in the form of a completely continuous film even in this scored portion. This also applies to the rivet portion 6, which is subjected to even more severe processing. In FIG. 3-B showing an enlarged cross-section of the sealing groove 3, the cross-sectional structure of the groove 3 is exactly the same as that in FIG. 3-A regarding the lid material, and in particular, the thermoplastic polyester film inner surface material 14 is It should be noted that they are provided throughout the area. This sealing groove 3 is lined with a sealing rubber composition (sealant) 16, and sealing is performed between the can body flange and the can body flange. In the case of the present invention, the thermoplastic polyester film inner material 14 is necessarily interposed between the can body member and the can lid at the double-sealed portion with the can body. It should be understood that the shell and can lid are electrically insulated. In the present invention, a thermoplastic polyester film is further used as the inner material 14, and the epoxy-phenol resin adhesive layer 13 connects the aluminum material base 11 and the inner material 14 to 3 kg/15 mm.
It should be bonded with an adhesive strength of at least 4 kg/15 mm width. Note that the adhesive strength is defined by the following method. That is, two samples of 100 mm x 15 mm are taken from an aluminum material coated with an inner film. After fixing the surfaces of the inner material films of this sample facing each other, they were heat-pressed at a temperature of 250°C using a hot press. One end of the heat-pressed sample in the longitudinal direction is peeled off in a T-shape, and the two ends of the peeled aluminum material are mounted on a tensile tester and tested at a tensile speed of 200 mm/min at a constant temperature of 25°C. The force required at this time of tension is defined as the adhesive strength Kg/15mm. The reason why adhesive strength is measured in this way is because if the adhesive strength of the laminate is directly peeled in a T-shape and the adhesive strength is measured, the adhesive strength will be large, and the inner material film will break during the measurement, making it impossible to measure the adhesive strength. It is. Although this test method does not directly indicate the adhesive strength of the laminate, it allows for relative comparison and evaluation of adhesive strength. Lid material As the aluminum material base, all the aluminum materials used for this type of easy-open lid can be used, such as pure aluminum or aluminum alloys containing aluminum and other alloying metals, especially aluminum alloys containing small amounts of magnesium, manganese, etc. is used. The thickness of the aluminum material varies depending on the size of the lid, etc., but it is generally 0.20 to 0.5 mm, especially
It is preferably within the range of 0.25 to 0.35 mm. As already pointed out, it is necessary to form a chromate treatment film on the surface of the aluminum material from the viewpoint of adhesion of the inner material to the aluminum material substrate and corrosion resistance. The chromate-treated film can be formed by means known per se, for example, by using an aluminum material,
This is carried out by chemical treatment by immersion in a treatment solution such as Allodin 401-45 (formulated by Amchem in the United States, Nippon Paint in Japan). The thickness of the chromate treatment film is expressed as the weight of Cr atoms per surface area.
It is preferably in the range of 5 to 20 mg/dm ² , particularly 5 to 20 mg/dm ² . As the thermoplastic polyester film used as the inner material 14, a thermoplastic polyester resin film mainly composed of ethylene terephthalate units is used, and in addition to a homopolyester film composed only of ethylene terephthalate units, it also contains a small amount of modified ester repeating units. Modified PET film is used. The film used has a tensile strength (according to ASTM D882) of 3 to 25 Kg/mm ² , preferably 5 to 20 Kg/mm ² . Thermoplastic polyester film has significantly higher tensile strength and tensile modulus than crystalline olefin resin film.
The impact strength is also amazing! It also has a high yield point and low elongation at the yield point. Dimensional stability is very good because the distortion due to stress is small. The film thickness is uniform and there are no pinholes, cracks, or sag. Excellent physical and mechanical properties over a wide temperature range. It has excellent moldability and does not break, pinholes, cracks, or sag when molded into can lids, scored, riveted, etc. It also has one of the best barrier properties (impermeability) against moisture and various corrosive components. The thickness of the inner material film is 10 to 100 μm, especially
The thickness is preferably in the range of 20 to 50 μm in order to satisfy corrosion resistance and ease of opening. The epoxy-phenol resin adhesive used for the epoxy-phenol resin adhesive layer 13 is an epoxy-phenol resin adhesive consisting of an epoxy resin a and a phenol aldehyde resin b. As the epoxy resin a, bis- or polyepoxide-type epoxy resin, that is, bisphenol A-
Bisepoxides, epoxy resins derived from bisphenols or other polyhydric phenols, and epihalohydrin are preferably used. These epoxy resins have the general formula In the formula, A is a divalent aromatic hydrocarbon residue derived from polyvalent phenols such as bisphenol A. An epoxy resin mainly having the chemical structure represented by the following, where n=0 to about 15. A known one is used. Suitable examples of the phenolaldehyde resin b include, but are not limited to, the following. general formula In the formula, R is a hydrogen atom, an alkyl group, a hydroxyl group, or a phenyl group, n is an integer of 1 to 3, m is an integer of 1 to 3, and the sum of n + m shall not exceed 5. Hydroxymethyl-substituted phenols represented by , . In the above formula, hydroxymethyl is preferably bonded to the ortho or para position with respect to the phenolic hydroxyl group. For example saligenin, o-
Hydroxymethyl-p-cresol, p-hydroxymethyl-o-cresol, o-hydroxymethyl-p-t-butylphenol, o-hydroxymethyl-p-phenylphenol, di(o-hydroxymethyl)-p-cresol , 2,4-dihydroxymethyl-o-cresol, 2,4-dimethyl-6-hydroxymethylphenol, resorcinol, mono- or dimethylolated products of catechol or hydroquinone. general formula In the formula, R ₂ represents a direct bond or a divalent bridging group, each of n' and m' is an integer up to 2 including zero, and the sum of n'+m' is an integer of 1 or more. , Rings A and B may be substituted with an alkyl group, a hydroxymethyl-substituted dinuclear phenol represented by: In the above formula (2), suitable examples of the bridging group _R2 are a methylene group, a methyleneoxymethylene group ( _-CH2 -O- _CH2- ), an ethylidene group, a 2,2-
Propylidene group

[Formula] Oxygen atom (-O-), Sulfur atom (-S-) sulfonyl group

[Formula] Imino group (-NH-), etc. In addition, hydroxymethyl derivatives of naphthols, such as 2-hydroxymethyl-1-naphthol and 2,4-dihydroxymethyl-1-naphthol, can also be used. These phenolic aldehyde resins can be used alone or in combination, but preferably a combination of those of the above formula (2) and (3) is used. The above-mentioned epoxy resin component a and phenolaldehyde resin component b can be used in combination in any ratio, and are not particularly limited. From the viewpoint of adhesive strength and retort resistance of the bonded part, it is recommended to use an adhesive that combines the two at a weight ratio of a:b=95:5 to 5:95, especially 90:10 to 10:90, when forming the adhesive layer. It is desirable to use it for In the present invention, the epoxy resin and phenolaldehyde resin include ketones, esters,
It is also possible to mix the resin in a dissolved state in an alcohol, hydrocarbon solvent, or a mixed solvent thereof, and use it directly as a coating for the adhesive intervening layer. It is desirable to pre-condense the mixture at a temperature for about 1 to 10 hours and then use it as an adhesive. This adhesive is applied to the chromate-treated surface of the aluminum base that will become the inner surface of the can to form an adhesive layer on the bonding surface of the base. The thickness of the adhesive layer is preferably 0.3 to 3 μm as a dry coating film. When the thickness is within this range, the adhesive strength over time is significantly improved. Further, the adhesive layer 13 is formed into a multilayer structure, and as shown in FIG.
can be provided. Examples of the adhesion promoter used in the adhesion promoter layer 13a include the above-mentioned epoxy resin a, which is a liquid or low melting point (74°C or less) epoxy resin with an epoxy equivalent in the range of 170 to 500, and the above-mentioned phenolaldehyde resin. an ultrathin layer of b, preferably from 1 to 100 angstroms (Å);
Particular mention may be made of bonding thin layers with a thickness of 1 to 30 Å. The formation of these adhesion promoter thin layers is preferably carried out by maintaining the surface of the aluminum material at a temperature of 150°C or higher, particularly at a temperature of 180 to 300°C, most preferably at a temperature of 200 to 250°C; The aluminum material is exposed to an atmosphere filled with the adhesion promoter in a high temperature atmosphere. The improvement in bond strength over time is most significant when the chromated aluminum material is coated with an ultra-thin layer of adhesion promoter. The inner material film is laminated onto the aluminum material substrate by overlapping the inner material film on the chromate-treated surface of the aluminum material substrate, and bonding them together by thermocompression at a temperature above the softening point and below the melting point of the inner material film polyester. It can be carried out. In this way, the aluminum material base and the inner material film are
It is possible to bond with an adhesive strength of Kg/15 mm width or more, and when the lid material is opened, a laminate can be obtained in which the inner material film breaks according to the score. The protective coating to be applied to the outer surface of the lid may include thermosetting resin paints, such as phenol-formaldehyde resin, furan-formaldehyde resin, xylene-formaldehyde resin, ketone-formaldehyde resin, urea-formaldehyde resin, Melamine-formaldehyde resins, alkyd resins, unsaturated polyester resins, epoxy resins, bismaleimide resins, triallyl cyanurate resins, thermosetting acrylic resins, silicone resins, oil-based resins, or thermoplastic resin coatings, such as vinyl chloride-vinyl acetate Copolymer, vinyl chloride
Partially saponified vinyl acetate copolymer, vinyl chloride
Maleic acid copolymer, vinyl chloride-maleic acid-
Examples include vinyl acetate copolymers, acrylic polymers, and saturated polyester resins. These resin coatings may be used alone or in combination of two or more. Forming into an Easy-Open Lid and Sealing with a Can The forming into an easy-open lid used in the present invention is performed by means known per se, except for using the above-mentioned laminate. To explain this process, first, in press molding process A, a laminate sheet of an inner material film and an aluminum base material is punched into a disc shape and formed into a desired lid shape. Next, in a score engraving step B, a score die is used to engrave a score so that the score reaches halfway into the aluminum substrate from the outer surface side of the lid.
Residual thickness of aluminum material in score t ₂
is for the original thickness t ₁ of the aluminum material base,
It is preferable that t ₂ /t ₁ ×100 be 20 to 50% and t ₂ be 70 to 130 μm. In the rivet forming step C, a rivet is formed by using a rivet forming die to protrude outward from the opening portion defined by the score, and in the tab attaching step D, an opening tab is fitted to the rivet and the protruding portion of the rivet is formed. Fix the tab by riveting it. Finally, in the lining step E, a sealing compound is applied as a lining to the sealing groove of the lid through a nozzle and dried to form a sealant layer. To explain the double seaming process with the can body, the flange of the can body member and the sealing groove of the easy-open lid are fitted together, and the groove is first seamed around the flange using a primary seaming die. let Then,
In the secondary seaming process, this flange is further
It is further seamed at 90 degrees along the side wall of the can body to obtain the can body of the present invention. In the present invention, the can body member is made of stain-free steel (TFS electrolytic chromic acid treated steel plate), which has adhesive (nylon adhesive) joints and welded joints on the side surfaces and seam flanges on the top and bottom. ) can body members for three-piece cans and TFS can bodies for so-called two-piece cans formed by drawing or deep drawing are preferably used. In addition, the present invention relates to a three-piece can body made of tin-plated steel plate (tinplate) and equipped with soldered or welded seams, and so-called tinplate made by drawing and ironing, deep drawing, impact extrusion, etc. It is equally applicable to seamless can bodies made of (Operation and Effect) The easy-open lid used in the present invention is composed of an aluminum base material whose at least the inner surface of the can is chromate-treated, and a plastic film inner material provided on the inner surface of the can. As a method, a thermoplastic polyester film is used, and an aluminum material substrate and a thermoplastic polyester film are laminated via an epoxy-phenol resin adhesive layer provided on the bonding surface of the substrate, and the temperature is increased to a temperature higher than the softening point of the polyester. A distinctive feature is that it consists of a laminate bonded under thermocompression at a temperature below the melting point. In the present invention, the use of the above-mentioned thermoplastic polyester film as the inner material of the easy-open lid exhibits remarkable effects in terms of corrosion prevention of the aluminum material base, easy opening, seaming performance, etc. be. Thermoplastic polyester film has a nearly constant thickness and is completely continuous in the plane direction.
It is particularly excellent in that it is free from coating defects such as pinholes, cracks, blisters, and sag that are often observed in ordinary organic coatings. In addition, thermoplastic polyester resin has a large cohesive force and is also excellent in toughness. This film has a high tensile strength and a high tensile modulus, and has low distortion under stress and therefore has very good dimensional stability. It has the advantage that it can be maintained in a continuous coating state without breaking, pinholes, cracks, sagging, etc., even when molded into can lids, scored, riveted on pull tabs for opening, etc. The same applies to the double seaming process with the can body member. Another great feature of this film is that it has excellent barrier properties against moisture and various corrosive components. In the present invention, by using a thermoplastic polyester film as the inner material of the easy-to-open can lid, the continuity and integrity of the coating is maintained even after the can lid is processed, and it also serves as a barrier against corrosive components. It also exhibits barrier properties and maintains excellent corrosion resistance. Moreover, this resin film is interposed in the double-sealed part of the can body and the easy-open lid, and maintains electrical insulation between the two, so a battery is formed between the can body and the lid, and electricity is generated. Since the lid can be effectively prevented from being chemically corroded, the improvement in corrosion resistance becomes even more remarkable. Furthermore, in an easy-open lid, when the score is sheared, the inner material is also required to be broken along the same exact direction as the score is sheared. This score breakability (breakability of the inner material along the score) is influenced by the adhesion of the resin film to the aluminum substrate and the physical properties of the resin film. That is, the higher the adhesion of the film, the easier it is to shear the film accurately and sharply along the score. According to the present invention, the epoxy-phenol resin adhesive layer 13 is provided on the chromate-treated aluminum substrate surface, and the inner material film is bonded by thermocompression at a temperature above the softening point and below the melting point, thereby improving adhesive strength. It is possible to obtain an adhesive strength of 3 Kg/15 mm width or more, and the above-mentioned score part performs accurate shearing to perform the unsealing operation. On the other hand, as for the physical properties of the film, if the film has a certain degree of rigidity, sharp shearing at the score part is possible. In the present invention, by using a thermoplastic polyester film, shearing at the score portion can be easily performed. This thermoplastic polyester film has a high tensile modulus, a high yield point, and a low elongation at the yield point. It is difficult to stretch because the strain against stress is small. On the other hand, in the case of a film such as an olefin film that has a low elastic modulus and is easily stretched, the film tends to be sheared while protruding from the score shearing section. Furthermore, in the present invention, compared to the case where the sealing compound is applied directly to the aluminum substrate or the case where the sealing compound is applied through a normal coating film, the sealing compound is applied through the thermoplastic polyester film layer described above. It has been found that the sealing performance of the double-sealed portion can also be improved by providing the double-sealed portion. This is thought to be because the plasticity of the resin film that is present throughout the double-sealed portion helps prevent leakage. (Example) The present invention will be explained by referring to an example. Example 1 Commercially available aluminum plate (thickness) used for can lids
0.37mm, 5052H38 material, surface alodine 401-45 treatment,
Chromium content 20mg/m ² ) with epoxy/phenolic resin (epoxy resin/phenolic resin: 60/40)
After applying the adhesive to a thickness of 1 μm and air-drying it, a 25 μm thick polyethylene terephthalate film (specific gravity 1.38, tensile strength 19.3~
(24.6Kg/mm ² , softening point 150℃) was thermocompression bonded at 220℃. Thereafter, an epoxy/urea paint was applied to the back surface using a roll coater so that the film thickness after drying was 4 μm, and baking drying was performed at 200° C. for 10 minutes. The adhesive strength between the polyethylene terephthalate film and aluminum plate of this laminate material is 7.3
Kg/15mm. Note that the adhesive strength is measured at 100mm.
Using two 15 mm x 15 mm laminate plates, the polyethylene terephthalate surfaces were placed facing each other and hot-pressed at 250°C, followed by T-shaped peeling, and the peeling force at that time was taken as the adhesive strength. Punch out a lid with a diameter of approximately 70 mm (commonly known as 211 diameter) from this laminate material so that the laminate surface becomes the inner surface of the lid, and then punch out a lid with a remaining thickness of 0.27 mm from the outside of the lid.
0.1mm partial opening type score processing and riveting processing were performed. This 211 diameter aluminum lid is made by TFS.
After tightening the 350g can body, it was filled with a model corrosive solution containing 0.3% each of common salt and citric acid, and then
After tightly sealing the TFS lid, it was sterilized at 115°C for 60 minutes and stored at 50°C for 3 months. Three months later, the can was opened and a detailed observation was made, but no abnormalities such as whitening, film residue, or corrosion of the processed parts were observed. Comparative Example 1 The surface of the same commercially available aluminum plate as used in Example 1 was coated with polyethylene adhesive paint (epoxy/phenol paint and polyethylene oxide).
10 PHR added (paint described in Japanese Patent Publication No. 54-11836) was coated using a roll coater so that the film thickness after drying was 3 μm, and baked and dried at 200° C. for 10 minutes.
A polyethylene film with a thickness of 40 μm (specific gravity 0.925, tensile strength 1.1 to 2.1 Kg/mm ² , softening point
(95℃) was thermocompression bonded at 180℃. An epoxy/urea paint was applied to the back surface using a roll coater to a dry film thickness of 4 μm, and baked and dried at 185° C. for 10 minutes. The adhesive strength of this laminate material between polyethylene and painted aluminum plate is 4.5Kg/15
It was warm in mm. The adhesive strength was measured using two laminate plates of 100 mm x 15 mm, the polyethylene surfaces facing each other, hot-pressed at 180°C, followed by T-shaped peeling, and the peeling force at that time was taken as the adhesive strength. A 211-diameter lid was punched out from this laminate material in the same manner as in Example 1, and after being wrapped around a 350g TFS can body, it was filled with model liquid and sterilized at 115°C for 60 minutes, then heated to 50°C.
Saved with. When inspected three months later, corrosion had progressed throughout the score processing section, rivet section, and chuck wall radius section, leading to holes and leakage of model fluid. Comparative Example 2 Polypropylene adhesive paint (epoxy/phenol paint with maleic acid-modified polypropylene 2PHR added) was rolled onto the surface of the same commercially available aluminum plate as used in Example 1 so that the film thickness after drying was 3 μm. Apply using a coater and heat at 200℃.
Baking drying was performed for 10 minutes. thickness on its surface
A 40 μm polypropylene film (specific gravity: 0.91, tensile strength: 3.2 to 5.1 Kg/mm ² , softening point: 105° C.) was thermocompression bonded at 180° C. An epoxy/urea paint was applied to the back surface using a roll coater to a dry film thickness of 4 μm, and baked and dried at 200°C for 10 minutes.
The adhesive force between the polypropylene of this laminate and the painted aluminum plate was 2.5 kg/15 mm. The adhesive strength was measured using two laminate plates of 100 mm x 15 mm, the polypropylene surfaces facing each other, hot-pressing at 200°C, followed by T-shaped peeling, and the peeling force at that time was taken as the adhesive strength. From this laminate board, the common name is given as in Example 1.
Punch out the 211 diameter lid, perform score processing, and TFS
After tightening the 350g can body, fill it with model liquid and 115
Sterilization was performed at 50°C for 60 minutes, and the mixture was stored at 50°C. When the can was opened after 3 months and detailed observation was made, slight corrosion was observed in the score processing area, rivet area, and part of the chalk wall radius area, especially in the rivet area. In addition, there was film residue in the score opening area that was 1/2 to 3/4 of the opening area. Comparative Example 3 Caproic acid was vaporized at 210°C on the surface of the same commercially available aluminum plate as used in Example 1, and the coating was applied for 10 minutes in that atmosphere to form a film with a thickness of 18 Å (Patent Application No. 59). -76594 method). After that, epoxy/urea paint was applied to the back side using a roll coating method to a dry film thickness of 4 μm, and then heated at 250°C.
After heating and drying for 10 minutes, an aluminum plate coated on both front and back sides was created. The surface of this sheet is 20μm thick nylon 12 (specific gravity 1.1, tensile strength 7.3-8.4Kg/mm ² , softening point 190℃)
The film was thermocompression bonded at 220°C. The adhesive strength between the nylon film and aluminum plate of this laminate material was 2.7 kg/15 mm. The adhesive strength was measured using a 100mm x 15mm laminate plate 2.
Using a hot press, the nylon surfaces of the sheets were placed facing each other and thermocompression bonded at 200°C, followed by T-shaped peeling, and the peeling force at that time was taken as the adhesive strength. This laminate material is commonly called as in Example 1.
Punch out a 211 diameter lid, perform score processing and TFS
After wrapping it around the made 350g can body, fill it with model liquid,
Sterilization was performed at 115°C for 60 minutes, and the product was stored at 50°C. After three months, the can was opened and detailed observations were made.
Although no corrosion was observed in any of the processed parts, a film remained over the entire area of the score openings.

[Brief explanation of the drawing]

FIG. 1 is a front view of the easy-open lid used in the present invention, FIG. 2 is an enlarged side sectional view of the lid shown in FIG. 1, and FIG. 3-A is a score processing section of the lid shown in FIG. 1. 3-B is a partially enlarged sectional view showing the sectional structure of the seaming groove of the lid of FIG. 1, and FIG. 4 is a partially enlarged sectional view showing the sectional structure of the lid of the invention. FIG. 7 is a partially enlarged sectional view showing another example of the configuration. 1...Easy open lid, 3...Sealing groove,
4... Portion to be opened, 5... Score, 6... Rivet, 7... Pull tab for opening, 11... Aluminum material base, 12a, 12b... Chromate treatment layer, 13... Epoxy-phenol resin adhesive agent layer, 14... thermoplastic polyester film inner surface material.

Claims (1)

[Scope of Claims] 1. A packaging case formed by seaming together a can body member and an easy-open lid made of an aluminum material, wherein the easy-open lid is chromate-treated at least on the side that becomes the inner surface of the can. The aluminum material base and the thermoplastic polyester film inner material provided on the side that will become the inner surface of the can are stacked together with an epoxy-phenolic resin adhesive layer provided on the bonding surface of the base. In addition, the easy-open lid is made of a laminate bonded under heat and pressure at a temperature higher than the softening point and lower than the melting point of the polyester, and this easy-open lid has a score formed so as to reach halfway in the thickness direction of the aluminum material from the outer surface side. A case with an easy-open lid, characterized in that the can body member and the easy-open lid are tightly wound together with a polyester film inner surface material interposed therebetween.