JP2007137519A - Easily openable lid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an easily openable lid which is prevented from damage of a film or a molding tool due to accumulation of a lubricant adhering to the molding tool even without forming a top coat layer, and shows excellence in productivity and economical efficiency since a metallic plate is adhesively covered with a resin film. <P>SOLUTION: The easily openable lid made of a resin-coated metal plate obtained by covering a metallic base plate with a lubricant-containing biaxially stretched film via a primer is characterized in that the lubricant in the biaxially stretched film is a sphere of a mean particle diameter of 0.5 to 2.5 μm and a ratio of mean particle diameters (longer diameter/shorter diameter) of 1.0 to 1.2, that the amount of the lubricant compounded in the biaxially stretched film is 0.05 to 0.5 wt.%, and that a top coat layer is not formed on the bi-axially stretched film. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an easy open lid made of a resin-coated metal plate, and more particularly to an easy open lid that does not require the formation of an inner surface topcoat layer and is excellent in productivity and economy.

  Conventionally, so-called easy-open lids have been widely used as container lids that can be easily opened by hand without using special equipment. This container lid is made of a metal material from the viewpoint of workability, and uses a resin-coated metal plate obtained by applying a resin coating such as a polyester film to a surface-treated steel plate such as TFS or an aluminum alloy. In addition, a score is provided so as to reach the middle of the thickness direction of the metal plate, the opening portion is partitioned, a rivet is formed on the opening portion with the lid plate itself, and the pull tab is fixed with the rivet, It is used by being double-rolled between a flange of a can body member or the like.

  Such an easy open lid is made of a resin-coated metal plate in which a polyester film is coated on a metal plate via an adhesive primer (Patent Document 1). A lubricant is added to prevent wrinkling due to removal (for example, Patent Document 2), and this lubricant accumulates on the molding tool in the rivet molding process and damages the film. A top coat layer is formed on the inner surface of the metal plate to prevent the lubricant from adhering to the forming tool.

JP-A-62-52045 JP 2002-302558 A

However, when an easy open lid is formed using a resin-coated metal plate coated with a polyester resin or the like, the top coat layer is originally unnecessary unless the above-described problem due to the lubricant contained in the film occurs. If the top coat layer can be omitted, productivity and economy can be improved.
On the other hand, conventionally, when heating for forming the top coat layer was performed, the adhesion primer layer was also heated at the same time. The primer layer has the problem of insufficient heating.

  Accordingly, an object of the present invention is to form a resin coating on a metal plate with good adhesion without forming a topcoat layer without causing damage to the film or damage to the forming tool due to adhesion of the lubricant to the forming tool. It is to provide an easy-open lid with excellent productivity and economy.

According to the present invention, in an easy open lid comprising a resin-coated metal plate coated with a lubricant-containing biaxially stretched film via a primer on a metal substrate, the lubricant has an average particle size of 0.5 to 2.5 μm. And the average particle size ratio (major axis / minor axis) is spherical in the range of 1.0 to 1.2, and is blended in the ratio of 0.05 to 0.5% by weight in the biaxially stretched film. There is provided an easy-open lid characterized in that a topcoat layer is not formed on the biaxially stretched film.
In the easy open lid of the present invention,
1. The biaxially stretched film is one of polyethylene terephthalate, isophthalic acid copolymerized polyethylene terephthalate, naphthalene dicarboxylic acid copolymerized polyethylene terephthalate, and a blend of polyethylene terephthalate / polybutylene terephthalate.
2. The primer is composed of a one-end-modified epoxy resin having a number average molecular weight in the range of 3000 to 8000 and an alkali resol type phenol resin in a ratio (weight ratio) of 95: 5 to 50:50,
3. The primer thickness is 0.3 to 3 μm;
4). The biaxially stretched film has a thickness of 10 to 40 μm,
Is preferred.

According to the present invention, the lubricant contained in the polyester film can be deposited on the forming tool without forming a topcoat layer that had to be formed on the inner polyester film of the resin-coated metal plate. Therefore, damage to the resin coating is prevented, and an easy-open lid with excellent corrosion resistance can be provided.
The easy open lid of the present invention does not require the formation of a topcoat layer, so the process for forming the topcoat layer can be shortened and the molding tool can be prevented from being damaged. There are advantages.
Furthermore, by using a specific primer, elution of low molecular weight components is suppressed as well as excellent feathering resistance, and excellent flavor and hygiene can be obtained.

In the easy open lid of the present invention, the average particle diameter is 0.5 to 2.5 μm and the average particle diameter ratio (major diameter / longitudinal) is used as a lubricant blended in a biaxially stretched film coated on a metal substrate via a primer. It is an important feature to select a spherical shape having a minor axis of 1.0 to 1.2 and to contain it in a ratio of 0.05 to 0.5% by weight in the biaxially stretched film. This makes it possible to effectively prevent the adhesion and deposition of the lubricant on the molding tool, which has been a cause of damage to the resin coating, without forming a topcoat layer on the biaxially stretched film. is there.
In the present invention, it is important that the average particle size and the average particle size ratio (major axis / minor axis) of the lubricant and the blending amount are all within the above range. This is because the operational effects of the present invention described above cannot be obtained.

That is, as will be apparent from the examples described later, even if the average particle size ratio and the blending amount are within the above range, if the average particle size is smaller than the above range, the forming tool has micro-scratches. When the average particle diameter is larger than the above range, the film is damaged and the metal is exposed at the time of molding. (Comparative Example 5).
Even if the average particle size and blending amount are within the above ranges, if the average particle size ratio (major axis / minor axis) is out of the above range, micro-scratches are still generated on the forming tool and the film Adhesion deposition occurs (Comparative Example 6). Furthermore, even when the average particle size and the average particle size ratio are within the above range, if the blending amount is less than the above range, the film adheres to the forming tool (Comparative Examples 2 and 4). Further, if the amount is larger than the above range, minute scratches are generated on the forming tool (Comparative Example 3).
In the case of an agglomerated lubricant, even if the average particle size and blending amount are within the above ranges, the lubricant deposits on the forming tool, damages the film, and metal exposure occurs (Comparative Example). 7).

In the present invention, by using a biaxially stretched film containing the above-mentioned lubricant, it is possible to solve the problem of film damage due to adhesion and deposition of lubricant particles on the forming tool. As an adhesion primer for adhering a biaxially stretched film to a metal plate, a ratio of 95: 5 to 50:50 (one weight modified epoxy resin having a number average molecular weight in the range of 3000 to 8000 and alkali resol type phenol resin) It is preferable to use a material that is blended in a ratio).
This makes it possible to coat a lubricant-containing biaxially stretched film on a metal plate with good adhesion without using heating when forming the topcoat layer, and it has excellent film adhesion and corrosion resistance. It is possible to provide an open lid.
In addition, the cured coating film made of this primer has excellent anti-feathering properties, can be easily extracted into the contents, can reduce low molecular weight components produced by decomposition, etc., and has excellent hygiene and flavor properties. (Examples 1-5, 7-11, Comparative Examples 1-10).

(Biaxially stretched film containing lubricant)
As the biaxially stretched film as the coating resin in the resin-coated metal plate used for the easy open lid of the present invention, a film made of a thermoplastic resin, particularly a polyester resin, which has been conventionally used for a resin-coated metal plate can be used.
The polyester resin may be homopolyethylene terephthalate, but the acid component other than terephthalic acid is 30 mol% or less based on the acid component, and the alcohol component other than ethylene glycol is 30 mol% or less based on the alcohol component. It may be a copolymerized polyester alone or a blend thereof.

  Acid components other than terephthalic acid include isophthalic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, P-β-oxyethoxybenzoic acid, diphenoxyethane-4,4′-dicarboxylic acid, 5-sodium sulfoisophthalic acid, hexahydro Examples include terephthalic acid, succinic acid, adipic acid, sebacic acid, dodecanedioic acid, dimer acid, trimellitic acid, and pyromellitic acid.

  As alcohol components other than ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexylene glycol, diethylene glycol, triethylene glycol, cyclohexane dimethanol, ethylene oxide adduct of bisphenol A, Examples include glycol components such as trimethylolpropane and pentaerythritol.

The polyester should have a molecular weight in the film forming range, and the intrinsic viscosity [η] measured using a phenol / tetrachloroethane mixed solvent as a solvent is 0.5 dL / g or more, particularly 0.52 to 0.70 dL / It may be in the range of g in terms of barrier properties against corrosive components and mechanical properties.
Preferably, any of polyethylene terephthalate, isophthalic acid copolymerized polyethylene terephthalate, naphthalene dicarboxylic acid copolymerized polyethylene terephthalate, and a blend of polyethylene terephthalate / polybutylene terephthalate is preferable. These resins have particularly preferable adhesiveness with the primer, and are excellent in shearing property when breaking the score part, so that the feathering resistance can be improved.

As described above, in the present invention, in the biaxially stretched film, the average particle size is in the range of 0.5 to 2.5 μm, and the average particle size ratio (major axis / minor axis) is in the range of 1.0 to 1.2. It is important that the spherical lubricant in the above is blended in the biaxially stretched film in a proportion of 0.05 to 0.5% by weight.
When the average particle diameter of the lubricant is larger than the above range, coarse lubricant particles are the starting point during lid making, for example, during score processing or rivet processing, and metal exposure due to pinholes occurs. On the other hand, if the average particle size is smaller than the above range, the slipperiness of the film will be insufficient, making it difficult to form the film smoothly, causing wrinkles on the film, causing troubles during lamination, and to forming tools. Film deposition occurs.

Various lubricants can be used as long as the above particle diameter is satisfied. For example, inorganic lubricants such as silica, alumina, titanium dioxide, calcium carbonate, and barium sulfate, or organic materials such as a crosslinked silicon resin and a crosslinked polystyrene resin can be used. Examples of the lubricant include true spherical silica, true spherical silicon, true spherical calcium carbonate, and the like.
In addition to the above-mentioned lubricant, the biaxially stretched film can be blended with known film compounding agents, antiblocking agents, pigments, various antistatic agents, antioxidants, and the like according to known formulations.
The draw ratio of the lubricant-containing biaxially stretched film is generally preferably in the range of 3 to 5 times in the lateral direction and 3 to 5 times in the longitudinal direction, and the thickness of the lubricant-containing biaxially stretched film is generally 10 to 40 μm. It is preferable that it exists in the range.
When the thickness of the film is larger than the above range, the film may be stretched without breaking when the score portion is broken, and the feathering resistance may be lowered, and it is not preferable in terms of economy. On the other hand, if the thickness of the film is thinner than the above range, metal exposure may occur during lid molding.

In the present invention, the lubricant-containing biaxially stretched film only needs to be positioned as a surface layer on the inner surface side of the easy open lid, and a two-layer structure in which a lower layer is formed on the metal plate side can also be adopted.
Any of the above-described polyester resins can be used as the lower layer, but the upper layer is composed mainly of ethylene terephthalate units and contains at least one kind of isophthalic acid, naphthalenedicarboxylic acid and the like in an amount of 1 to 30 mol%. It is preferable from the viewpoint of work adhesion, dent resistance, and the like that the polyester resin has a larger amount than that of the acid component in the biaxially stretched film.
When used in a two-layer configuration, the thickness of the lower layer is preferably in the range of 5 to 32 μm, and the thickness ratio of the upper layer and the lower layer is in the range of 1: 1 to 1: 4, such as workability and corrosion resistance. To preferred.

(Primer)
In the present invention, as a primer for adhering the lubricant-containing biaxially stretched film to the metal plate, it exhibits excellent adhesion to both the metal plate and the polyester film and can be cured in a short time. It is important to omit the conventional top coat layer. In the present invention, particularly, the one-end-modified epoxy resin having a number average molecular weight in the range of 3000 to 8000 and the alkali resol type phenol resin are 95: 5 to 50. : 50, particularly 80:20 to 65:35 (weight ratio) can be suitably used.
Since this primer can be cured in a short time and the amount of elution of low molecular weight components such as bisphenol A is remarkably suppressed, it is particularly suitable for easy-open lids used for cans of food or beverages. It can be used suitably.

The epoxy resin is not particularly limited, and for example, any of bisphenol A type epoxy resin, bisphenol F type epoxy resin, brominated epoxy resin, cycloaliphatic epoxy resin, etc. can be used. Resin or bisphenol F type epoxy resin is used.
Examples of the modifier include phenols such as phenol, p-alkylphenol, and p-tertiary butylphenol, and bisphenol and organic acids. Preferred modifiers include phenol, p-cresol, and p-tertiary butylphenol. Etc.

The one-end-modified epoxy resin constituting the primer used in the present invention is obtained by modifying an epoxy group at one end to obtain an epoxy resin, so that it can be easily extracted from the cured coating into the contents of the can. A molecular weight component can be reduced, and a cured coating film excellent in hygiene and flavor can be obtained. In addition, the modified products at both ends have fewer reactive sites with the phenols used in the curing agent, so there is a high possibility that they will not be incorporated into the crosslinking reaction when the coating film is cured, which is a factor that impairs hygiene and flavor. This is not preferred because it tends to be formed, and the terminal unmodified epoxy resin has many low molecular weight decomposition products, which may impair the flavor properties.
In addition, as described above, the one-terminal modified epoxy resin is particularly preferably one having a number average molecular weight in the range of 3000 to 8000, and when the number average molecular weight is larger than the above range, the adhesion with the metal is reduced, Feathering resistance may be reduced. On the other hand, if the number average molecular weight is smaller than the above range, the primer becomes brittle, so that the primer itself may be agglomerated and broken at opening, and the feathering resistance is reduced. There is a fear.

On the other hand, as the alkali resol type phenol resin, those obtained by reacting phenols and aldehydes in the presence of a catalyst can be used. As phenols, o-cresol, p-cresol, p-phenylphenol, p-nonylphenol, 2,3-xylenol, 2,5-xylenol, phenol, m-cresol, 3,5-xylenol, bisphenol A, bisphenol F etc. are mentioned. Examples of aldehydes include formaldehyde and acetaldehyde.
The primer used in the present invention can be obtained by mixing the one-end-modified epoxy resin and the alkali resol type phenol resin in the above-mentioned quantitative ratio, precondensing, and adding a catalyst as necessary.

The amount ratio of the one-end-modified epoxy resin and the alkali resol type phenol is preferably in the range of 95: 5 to 50:50, particularly 80:20 to 65:35 (weight ratio), as described above. When the amount of the epoxy resin is larger than the above range, the primer curing is insufficient, the adhesion with the metal is lowered, and the feathering resistance may be lowered. On the other hand, if the amount of the epoxy resin is less than the above range, the phenol may be self-condensed and the primer may become brittle.
Examples of the catalyst include phosphoric acid, hydrochloric acid, sulfuric acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, oxalic acid, acetic acid and the like.
The primer layer is generally preferably provided with a thickness of 0.3 to 3 μm, and may be provided on a metal material in advance, or may be provided on a biaxially stretched film or a lower layer film. If the primer is thicker than the above range, the primer in the molded part may cause cohesive failure, resulting in peeling under the film and poor molding, while the primer layer is thinner than the above range. May be inferior in adhesion, and there is a risk that feathering resistance may be reduced.

(Metal plate)
As the metal plate used in the present invention, light metal plates such as various surface-treated steel plates and aluminum alloys are used. As the surface-treated steel sheet, a cold-rolled steel sheet is annealed and then secondary cold-rolled and subjected to one or more surface treatments such as galvanizing, tin-plating, nickel-plating, electrolytic chromic acid treatment, and chromic acid treatment. Can be used. Further, an aluminum-coated steel sheet subjected to aluminum plating, aluminum rolling, or the like is used. In addition to the so-called pure aluminum plate, an aluminum alloy plate is used as the light metal plate. Specific examples of the aluminum alloy plate include aluminum, aluminum-copper alloy, aluminum-manganese alloy, aluminum-silicon alloy, aluminum-magnesium alloy, aluminum-magnesium-silicon alloy, aluminum-zinc alloy, and aluminum-zinc-magnesium. Examples thereof include a core material made of an alloy, an aluminum alloy, and a clad material made of a pure aluminum layer having an aluminum purity of 99.5% or more. In addition, the surface of aluminum material is inorganic surface treatment such as phosphoric acid chromate treatment, zirconium phosphate treatment, phosphoric acid treatment, etc., polyacrylic acid treatment, organic surface treatment such as phenol resin and tannic acid, etc. It is desirable to form a surface treatment film such as an inorganic composite surface treatment.
The original thickness of the metal plate varies depending on the type of metal and the use or size of the container, but generally it should have a thickness of 0.10 to 0.50 mm. The thickness is preferably 10 to 0.30 mm, and in the case of a light metal plate, the thickness is preferably 0.15 to 0.40 mm.

(Resin coated metal plate)
FIG. 1 is a view showing a cross-sectional structure of an example of a resin-coated metal plate used for the easy open lid of the present invention. The resin-coated metal plate of the present invention, indicated as a whole by 1, has a metal plate 2 and a lubricant-containing biaxially stretched film 4 formed on the surface of the metal plate 2 on the inner surface of the easy open lid via a primer layer 3. Has been. Further, a protective coating film 6 is formed on the surface of the metal plate 2 on the side that becomes the outer surface of the easy open lid.
FIG. 2 is an example in which the lubricant-containing biaxially stretched film 4 in the resin-coated metal plate of FIG. 1 has a two-layer structure formed of an upper layer 4-1 and a lower layer 4-2 on the primer layer 3 side.
The resin-coated metal plate used in the present invention is prepared by previously preparing the above-mentioned lubricant-containing biaxially stretched film by a conventionally known method, and laminating it on a metal plate coated with a primer, or forming a lubricant-containing biaxially stretched film. A primer is applied and laminated on a metal plate.

(Easy open lid)
The easy open lid of the present invention can take a conventionally known shape except that the surface on which the above-mentioned lubricant-containing biaxially stretched film of the resin-coated metal plate is formed is the inner surface side of the lid, Either a full open method or a partial method may be used.
The easy open lid is formed by first stamping the resin-coated metal plate into a disk shape and forming it into a desired lid shape in a press molding process. Next, in the score marking step, the score is stamped using a score die so that the score reaches the middle in the thickness direction of the metal material from the outer surface side of the lid. In the rivet forming step, a rivet protruding outward is formed on the opening portion partitioned by the score using a rivet forming die, and in the tab attaching step, the opening tab is fitted to the rivet, and the protruding portion of the rivet is The easy open lid is formed by taking out and fixing the tab.

3 and 4 show a partial type easy-open lid which is an example of the easy-open lid of the present invention. 3 is a top view, and FIG. 4 is a cross-sectional view taken along line AA in FIG.
The easy-open lid of the present invention, indicated as a whole by 10, comprises a central panel portion 11, a reinforced annular groove 12, and an outermost winding tightening portion 13. The central panel portion 11 has a planned opening portion 15 surrounded by a score 14, and an opening tab 16 is fixed through a rivet 17. The opening tab 16 includes a grip ring 18, a pushing tip 19, and a rivet fixing tongue 20, and is attached so that the pushing tip 19 overlaps the planned opening portion 15. The reinforcing annular groove 12 includes an inner wall portion 22, a radius portion 23 and an outer wall portion (chuck wall) 24 from the central panel portion 11 through a central panel radius portion 21, and the outer wall portion 24 is a seaming panel portion 25. And connected to the curled portion 26. The back side of the seaming panel portion 25 and the curl portion 26 is a groove 27, and a sealing composition (not shown) is lined in the groove 27, and between the can body flange (not shown). Sealing by double winding is performed.

(Washing aluminum alloy plate)
Commercially available aluminum-manganese alloy plate (JIS 5021, plate thickness: 0.25 mm)
) Using a commercially available strong alkaline degreasing agent “Fine Cleaner 4377” (trademark, manufactured by Nihon Parkerizing Co., Ltd.) under the conditions of a chemical concentration: 20 g / L, a processing temperature of 60 ° C., and a processing time of 7 seconds. did. Thereafter, the alkali remaining on the surface was washed with tap water.

(Processing to aluminum alloy plate)
After the surface treatment was performed on the obtained aluminum alloy plate using a surface treatment solution of “Alchrome K702” manufactured by Nihon Parkerizing Co., Ltd. at a temperature of 50 ° C. to 60 ° C. and a treatment time of 1 second to 5 seconds, unreacted substances were removed. After washing with tap water, it was further washed with deionized water of 3000,000Ω or more, and then dried at 80 ° C. to obtain a surface-treated aluminum plate.

(Preparation of primer)
500 parts by weight of Epoxy Resin Epicoat 1010 (molecular weight 5500, epoxy equivalent 4000) manufactured by Japan Epoxy Resin Co., Ltd. and 20 parts by weight of p-tertiary butylphenol were charged into the reactor, heated to 60 ° C. while stirring, and then 10% by weight. Add 0.4 parts by weight of concentrated sodium hydroxide solution, gradually raise to 140 ° C, start polymerization, further raise to 170 ° C, take out the contents when the contents become constant, and cool to room temperature Thus, an epoxy resin having one end modified with p-tertiary butylphenol was obtained (molecular weight 5700, epoxy equivalent 7300).

500 parts by weight of p-cresol and 250 parts by weight of formalin were reacted in the presence of a magnesium hydroxide catalyst, purified, and dissolved in a solvent to prepare a resol type phenol formaldehyde resin solution.
The one-end-modified epoxy resin and the resol type phenol formaldehyde resin are mixed at a solid content weight ratio of 70:30, precondensed, and phosphoric acid is blended at a ratio of 0.2 parts by weight with respect to the solid content. Thus, primers were prepared (Examples 1 to 5, Comparative Examples 1 to 10).
Similarly, the primer was prepared by mixing at a solid content weight ratio of 40:60 to 98: 2, precondensed, and blending phosphoric acid at a ratio of 0.2 parts by weight with respect to the solid content (implementation). Examples 6-12).

Also, 500 parts by weight of Epoxy Resin Epicoat 1010 (molecular weight 5500, epoxy equivalent 4000) manufactured by Japan Epoxy Resin Co., Ltd. and 50 parts by weight of p-tertiary butylphenol were charged into the reactor and heated to 60 ° C. while stirring. Add 0.4 parts by weight of a sodium hydroxide solution with a concentration of% by weight, gradually raise the temperature to 140 ° C, start polymerization, further raise the temperature to 170 ° C, take out the content and cool it to room temperature. Thus, an epoxy resin having both ends modified with p-tertiary butylphenol was obtained (molecular weight 5800, epoxy equivalent 14000).
The both-end-modified epoxy resin and the above-mentioned resol type phenol formaldehyde resin are mixed at a solid content weight ratio of 70:30, precondensed, and phosphoric acid is added at a ratio of 0.2 part by weight to the solid content. A primer was prepared by blending (Example 13).
Furthermore, the epoxy resin Epicoat 1010 manufactured by Japan Epoxy Resin Co., Ltd. and the above-mentioned resol type phenol formaldehyde resin were mixed at a solid content weight ratio of 70:30, pre-condensed, and phosphoric acid was added to the solid content in an amount of 0.00. A primer was prepared by blending at a ratio of 2 parts by weight (Example 14).

(Production of film)
Isophthalic acid 11 mol% copolymerized polyethylene terephthalate containing 0.1% by weight of a true spherical silica lubricant having an average particle diameter of 1.5 μm and an average particle diameter ratio of 1.1 is melt extruded at 260 to 290 ° C. The film was rapidly cooled and solidified to obtain an unstretched film, and this unstretched film was stretched 3 to 5 times in the machine direction at 80 to 110 ° C, and then stretched 3 to 4 times in the transverse direction at 90 to 130 ° C. Then, it manufactured by heat-setting a film at 160-195 degreeC. The film thickness after stretching of this film was 30 μm (Examples 2, 6 to 14).
Similarly, films having different average particle diameters, average particle diameter ratios, and blending amounts of lubricants were prepared (Examples 1, 3-5, Comparative Examples 1-10).
The average particle size and average particle size ratio of the lubricant were measured by observing the lubricant used with an electron microscope and measuring the particle size and particle size ratio (major axis / minor axis), and taking an average value of n = 50. .

(Applying primer to film)
The primer was applied to one side of the film so that the thickness after drying was 1 μm, and dried in an oven at 100 ° C.
(Production of laminate plate)
The surface-treated aluminum plate was heated to 230 ° C., and the isophthalic acid copolymerized polyethylene terephthalate resin film coated with the prepared primer was laminated at a laminating roll temperature of 150 ° C. and the feeding speed so that the primer coating surface was on the aluminum plate side. An aluminum alloy plate laminated on one side was prepared by heat laminating at 150 m / min and immediately cooling with water.

(External paint application)
An epoxy urea paint was applied to the non-laminated surface of the single-sided laminated aluminum alloy plate (film thickness after drying: 3 μm) and baked at 185 ° C. for 10 minutes to obtain an aluminum alloy can lid material.

(Production of can lid)
The prepared resin-coated aluminum alloy can lid material is punched to a diameter of 68.7 mm in the direction in which the laminate surface is on the inner surface side of the lid, and a sealing compound is applied to the portion to be the inner surface side of the curled portion and dried. Next, partial opening type score processing (score remaining thickness 110 μm, score width 20 μm), rivet processing, and attachment of an opening tab were performed on the outer surface side of the lid, and an easy open lid was produced. Table 1 shows the compositions of the primers of Examples and Comparative Examples, and the average particle size, shape, average particle size ratio, and blending amount of the lubricant.

(Evaluation methods)
The following evaluation was performed and the results are shown in Table 2.
1. Film winding property during film formation Since the slipperiness of the film was insufficient due to the average particle size and blending amount of the lubricant and the film was wrinkled, the presence or absence of wrinkling of the film was evaluated.
○: No wrinkle ×: Wrinkle occurred

2. Evaluation of the condition of the rivet forming tool In the rivet forming process, a rivet protruding outward is formed on the opening portion partitioned by the score using a rivet forming die, and the opening tab is fitted to the rivet in the tab attaching process. The state after forming about 100,000 sheets of the forming tool that contacts the inside of the rivet when the protruding portion of the rivet was beaten to fix the tab was evaluated.

3. Evaluation of metal exposure of the lid A 1% saline solution was injected as an electrolytic solution into an acrylic resin container having an electrode with a diameter that fits with the easy open lid, and the easy open lid was mounted so that the liquid did not leak. Next, a voltage of 6.3 V was applied, and the degree of metal exposure was evaluated by the energization amount A (note that practical aptitude is 0.5 mA or less). Each n = 200 sheets.
○: 0 ≦ A ≦ 0.5 mA
Δ: 0.5 <A ≦ 2.0 mA
×: 2.0 mA <A

4). Flavor evaluation Distilled water was filled into a TFS two-piece can body for general foods, and an easy-open lid was tightened according to a conventional method, and the retort was sterilized (at 125 ° C for 30 minutes), and the flavor was evaluated. ×: Feel the resin odor

5. Feathering evaluation For easy-open lid, the lid was actually opened before and after retort sterilization (at 115 ° C for 60 minutes), and the occurrence of feathering L in the opening was evaluated (practical aptitude is 1.5 mm or less) is there). Each n = 270 sheets.
○: 0 ≦ L ≦ 1.0 mm
Δ: 1.0 <L ≦ 1.5 mm
×: 1.5 mm <L

It is a figure which shows an example of the cross-section of the resin coating metal plate used for the easy open lid | cover of this invention. It is a figure which shows another example of the cross-section of the resin coating metal plate used for the easy open lid | cover of this invention. It is a top view of an example of the easy-open lid | cover of this invention. It is an expanded sectional view in line AA of FIG.

Claims (5)

In an easy-open lid comprising a resin-coated metal plate coated with a lubricant-containing biaxially stretched film via a primer on a metal substrate,
The lubricant has a spherical shape with an average particle diameter of 0.5 to 2.5 μm and an average particle diameter ratio (major axis / minor axis) of 1.0 to 1.2. An easy-open lid characterized in that it is blended in a proportion of 05 to 0.5% by weight and no top coat layer is formed on the biaxially stretched film.   2. The easy open lid according to claim 1, wherein the biaxially stretched film is any one of polyethylene terephthalate, isophthalic acid copolymerized polyethylene terephthalate, naphthalene dicarboxylic acid copolymerized polyethylene terephthalate, and a blend of polyethylene terephthalate / polybutylene terephthalate.   The primer is formed by blending a single-end-modified epoxy resin having a number average molecular weight in the range of 3000 to 8000 and an alkali resol type phenol resin in a ratio (weight ratio) of 95: 5 to 50:50. The easy open lid according to 1 or 2.   The easy open lid according to any one of claims 1 to 3, wherein the primer has a thickness of 0.3 to 3 µm.   The easy open lid according to any one of claims 1 to 4, wherein the biaxially stretched film has a thickness of 10 to 40 µm.

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