JPH0631091B2 - Easy-to-open can lid that can protect the cutting edge - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an easily openable can lid capable of protecting a cut edge, and more particularly, to easily open a can of canned food without using a special device. The easy-open can lid having the function of preventing the injury of fingers and the like by being covered with the resin whose sharp opening cut edge extends outwardly from the edge when being opened. Regarding

(Prior Art) Conventionally, what is generally called a full open can is known as an easily openable can lid for canning. This can lid is provided with an opening score for partitioning the portion to be opened in the can lid, and an opening tab is provided at the portion to be opened.When opening, the score is sheared and the portion to be opened is It is removed from the area around the can lid. There is a sharp cutting edge around the detached portion, and an accident that an injury is often caused by touching this with a finger.

Many proposals have been made to prevent the above-mentioned injury by covering a sharp cutting edge formed by score cutting with a resin coating band which is applied to the can lid in advance. For example, a resin-coated band is provided on the inner surface or the outer surface of the can lid so as to straddle the score, and the resin-coated band is also broken when the score is broken, and the cut edge of the removed part remains Those in which both edges are protected (Japanese Patent Publication No. 54-20907, Japanese Patent Publication No. 57-44540)
No. gazette) or a resin coated band is provided so as to straddle the score, but when opened, the resin coated band is not broken and remains in the state of being adhered to the removed part side or the remaining peripheral part side. Things (Japanese Patent Publication No. 51-18872 and
Japanese Utility Model Laid-Open No. 60-10728) is known.

(Problems to be solved by the invention) However, in the former type of resin-coated band, the resin-coated band is made relatively fragile or thin so that the resin-coated band is broken at the same time as the score. In addition to the above, it is insufficient to prevent direct contact between the cutting edge and the finger because the resin coating is flush with the cutting edge of the can lid, and the protective effect is still sufficient. It can not be said.

In the latter type of easy-open lid with a resin-coated band, the adhesive primer is applied to the part of the can lid where the resin-coated band remains, and the primer is applied to the part where the resin-coated band is peeled off. It requires complicated operations such as not doing so, and it has not been sufficiently satisfactory in terms of productivity and cost. Further, when the above-mentioned means for separately coating the paint is not used, it is strictly determined whether the resin coating band adheres to the part side to be removed and migrates, or adheres to the remaining peripheral part side and migrates. It will be difficult to control.

Therefore, an object of the present invention is to provide a space between the resin-covered band outside the opening score and the can lid peripheral portion at the time of unsealing while having the same outer coating film on both the can lid opening portion and the can lid peripheral portion. It is an object of the present invention to provide an easily-openable can lid in which peeling occurs reliably and the opening is performed with the cut edge of the opening being covered with the resin coating band.

Another object of the present invention is to provide an easily-openable can lid provided with a mechanism for surely fixing a resin-coated band to a portion to be opened when opening.

(Means for Solving Problems) The inventors of the present invention provide a rim portion or a step portion inside the opening score of the can lid, and provide a resin coating band so as to cover the rim portion or the step portion. At times, the rim portion or the stepped portion serves as a can lid-resin coated belt engaging mechanism for effectively preventing the radial movement of the resin coated belt, and the portion of the can lid to be opened is also the peripheral portion of the can lid. Even if they have the same outer surface coating, peeling occurs between the resin-coated band outside the opening score and the peripheral part of the can lid, and the cut edge of the opening is a resin-coated band projecting outward from it. Opening is performed in the covered state, and the resin coated band used is the following formula In the formula, A is the adhesive strength per unit width (cm) between the resin coating band and the lid, T is the strength per unit width (cm) of the resin coating band, and C is a constant (900). is there.

In the case of a resin-covered band that satisfies the above conditions, the resin-covered band is prevented from breaking, and at the time of opening, the fixing of the coating band to the portion to be opened and the peeling of the coating band from the periphery of the can lid are ensured. I found that I could do it.

(Function) In the easily-openable can lid of the type in which the resin-coated band is not broken together with the score and is opened in a state of being fixed to the portion to be opened, the contact between the resin-coated band and the can lid is
It must be done in an area called peel adhesion.
Peelable adhesion is defined as the adhesive strength at the interface is lower than the cohesive failure force of the resin, and this adhesive strength is lower than the opening force by a finger.

The area where the can lid is to be opened and the area around the can lid are distinguished by applying or not applying adhesive paint, or by different adhesive strengths.
When each type of paint is provided, it is possible to bond and fix the resin-coated band to the portion to be opened while maintaining the adhesive strength between the can lid peripheral portion and the resin-coated band in the peelable adhesive region described above. However, if the area of the can lid to be opened and the area around the can lid have the same outer surface coating, there is a difference in the adhesive strength between the area to be opened and the area around the can lid with the score as a boundary. It will be very difficult to give.

Moreover, from the viewpoint of the corrosion resistance of the can lid, it can be said that it is essential to provide a coating film with excellent corrosion resistance on the entire surface of the can lid. For example, this corrosion resistant coating film is required to have excellent processability. From this point of view, it is desirable that the coating applied to the outer surface of the can lid is the same coating on both the opening portion and the peripheral portion of the can lid, and it is complicated to apply the same coating on the entire outer surface of the can lid. It is also desirable in terms of avoiding operations, simplifying the process, increasing productivity, and reducing can lid manufacturing costs.

The present invention relates to an opening score for partitioning a portion to be opened provided on a can lid, an opening tab provided to a portion to be opened, and an upper score portion between the portion to be opened and the peripheral portion of the can lid. The present invention relates to an easily-openable can lid, which comprises a resin coating strip for protecting the cutting edge provided so as to straddle the outer surface of the can lid. (B) A rim portion or a step portion is provided inside the opening score of the can lid, and a resin coating band is provided so as to cover the rim portion or the step portion. (C) This resin coating Obi is the following formula In the formula, A is the adhesive strength per unit width (cm) between the resin coating band and the lid, T is the strength per unit width (cm) of the resin coating band, and C is a constant (900). is there.

(D) When opening, peeling occurs between the resin-covered band outside the opening score and the peripheral portion of the can lid, and the cut edge of the opening is covered with the resin-covered band. It is characterized by the combination that the opening is performed in the opened state.

Each requirement will be described below.

Regarding the requirement of (a), in terms of the corrosion resistance of the can lid, it is indispensable to provide a coating film with excellent corrosion resistance on the entire surface of the can lid. In view of the conditions, this corrosion resistant coating film is required to have excellent workability. From this point of view, the coating applied to the outer surface of the can lid is required to have the same coating in both the portion to be opened and the peripheral portion of the can lid.

Moreover, forming the same coating film on the entire outer surface of the can lid has the advantages of avoiding complicated coating operation, simplifying the process, increasing productivity, and reducing the manufacturing cost of the can lid.

The requirement of (b) is that the resin coated band seals the opening score,
Further, it is for ensuring the adhesion to the opening side at the time of opening the package so that the peeling may occur on the peripheral side of the can lid. Since the opening score part has a thin metal plate and there is no coating on the outer surface, it is necessary for the resin-coated band to sufficiently seal the opening score so that peeling does not occur during transportation and handling of the can. It is necessary for the peripheral part of the can lid to be peeled off to cover the sharp cutting edge on the opening side.

In the present invention, a rim portion or a step portion is provided inside the opening score, and the resin-coated band seals the opening score and is bonded over the rim portion or the step portion. Since the end portion is bent downward and adheres to the coating film on the can lid, the adhesive force of the resin coating strip to the can lid is significantly improved.
It is prevented from peeling from the end. Furthermore, it can sufficiently withstand the tensile force in the radially outward direction, and can function as an anchor.

This has a remarkable effect of preventing peeling when the can is subjected to shock or vibration during handling or transportation. Further, the provision of the rim portion or the stepped portion strengthens this portion of the can lid and the vicinity thereof to help prevent deformation, protects the opening score, and prevents peeling of the resin coating band.

The requirement of (c) indicates that there is an appropriate range for the adhesive strength of the resin-coated strip to the base coating film, the strength of the resin-coated strip, and the like. By satisfying the above formulas (1), (2) and (3), it is possible to prevent the resin-coated band from breaking while ensuring that the resin-coated band is fixed to the area to be opened and peeled from the peripheral part of the can lid. It is something that can be done.

The above formula (1) relates to the balance between the easy-open property and the fixing of the resin-coated band, and when the adhesive strength (A) exceeds 2000 g / cm, peeling of the resin-coated band becomes difficult over the entire surface and the lid The effect on the opening force becomes too large, making it difficult to open the lid, or in the worst case, opening is impossible. Also,
If the adhesive strength (A) is less than 10 g / cm, it becomes difficult to fix the resin-coated band, and the resin-coated band peels off from the lid during handling, heat sterilization, and transportation, which serves as a protective function. Disappear.

The above formula (2) relates to preventing breakage of the resin-coated band, and when the strength (T) of the resin-coated band becomes 20 g / cm or less, the resin-coated band will break at the time of opening. The cut edge of the lid opening cannot be covered with the resin coating band protruding outwardly from the cut edge.

The above formula (3) is also related to the peeling of the resin-coated band from the can lid and the breakage of the resin-coated band.If the above-mentioned formula (3) is not satisfied, the resin-coated band should be around the can lid when opening. Without being peeled off from the part, it breaks and the role of protecting the cut edge part is not fully fulfilled.

The requirement of (d) is that by satisfying the requirements of (a), (b) and (c) above, when the can lid is opened, the space between the resin coating band outside the opening score and the can lid peripheral part is Then, peeling occurs, and the opening can be opened in a state where the cut edge is covered with the resin coating band.

(Explanation of a preferred embodiment) The can lid-resin coating band engagement mechanism of the present invention comprises a rim portion or a step portion provided inside the opening score of the can lid, and covers the rim portion or the step portion. A resin coated band is provided on.
A second score may be provided between the rim portion or stepped portion and the opening score to provide an auxiliary engagement mechanism with the resin coating.

The present invention is not limited to the following cases, but in particular, the resin coating band is provided with a relatively small width from the upper part of the score to the peripheral part of the can lid, and reaches the engaging mechanism from the upper part of the score to the part to be opened. It is desirable to have a relatively wide width.

The coating film provided on the entire outer surface of the can lid should be an organic resin protective coating film with excellent corrosion resistance and work resistance, while the resin coating band is made of an elastomer from the viewpoint of protecting the fingers. Is desirable. The combination of the two, the above formula (1),
It should satisfy (2) and (3), and more preferably the formula Should be satisfied.

The present invention will be described based on specific examples shown in the accompanying drawings.

FIG. 1 is a top view of the lid of the present invention, and FIG.
3 and FIG. 3B showing an enlarged cross section of the main part, the can lid 1 has a metal material 2 and an outer surface protective coating 3a applied to the entire outer surface and the inner surface thereof, as shown in FIG. 3B. It has a cross-sectional structure composed of the inner surface protective coating film 3b applied to the entire surface.

This lid 1 has a circumferential groove portion 4 on the outer circumference and an annular rim portion 5 on the groove portion.
And a panel portion 6 which is continuous through the groove portion 4 and a sealing compound layer 7 which is sealingly engaged with the can body flange (not shown) at the time of double winding. Inside the annular rim 5 there is a portion 9 to be opened, which is delimited by a score 8. The opening portion 9 may substantially coincide with most of the panel portion 6, or a part of the panel portion 6 may be the opening portion. Score 8
Is provided so as to reach the middle of the metal material 2 in the thickness direction, as shown in the enlarged sectional view of FIG. 3-B.

An opening tab 10 is provided on the opening portion 9 by a mechanism described below. The unsealing tab 10 has a score cleaving tip 11 at one end, a grip portion (ring) 12 at the other end, and a fulcrum portion 13 located between them and joined to a lid. In this example, the fulcrum part 1
3 has a tab between the tip 11 and the ring 12 and is provided with a notch 14 having a substantially U-shape so that a connecting portion 15 exists between the fulcrum portion 13 and the tip 11 to form a tongue shape. It is formed by doing. The tearing tip 11 of the unsealing tab 10 is bonded to the opening portion 9 of the lid body by, for example, a thermoplastic resin adhesive at the tongue-shaped fulcrum portion 13 so that the position thereof substantially coincides with the score 8 of the lid body. It is fixed by being heat-bonded through the agent layer 16.

A second score 17 is provided inside the score 8 that defines the opening portion 9, and a rim portion or a step portion 18 is provided inside the score 8 at a smaller interval than the second score. On the outer surface side of the winding lid 1, a resin coating strip 19 made of an elastomer for protecting the cutting edge is provided so as to straddle the score 8. The resin-coated band 19 is provided over the entire circumference of the score 8 and, as is often shown in Section 3-B, the score 8
The outer side is provided with a relatively small width, and the inner side with respect to the score 8 is provided with a relatively wide width so as to completely cover the second score 17 and the rim portion 18. Further, it is understood that the resin coated band 19 is also filled inside the second score 17, that is, in the groove.

In this concrete example as well, the ring 2 of the opening tab 10 is used in the can lid.
When the finger is gripped and lifted upward, this force is transmitted as a downward force to the cleaving tip 11 via the fulcrum portion 13, and a downward cleaving force is added to the score 8 to give a score 8
Shearing is started. Then, by opening the opening tab 10 further upward, the opening portion 9 is also lifted upward, the shearing of the score 8 further progresses, and the opening portion is removed. In FIG. 4 explaining the stage in the middle of this opening, it can be seen that there is a step between the opening portion 9 and the outer peripheral portion 20 during the shear opening of the score 8. The second score 17 and the rim portion or step portion 18 described above.
It will be appreciated that has the effect of engaging the resin coating strip 19 and preventing and securing the coating strip 19 from being pulled radially outward. Also, the opening portion 9
Due to the step formed between the outer peripheral portion 20 and the outer peripheral portion 20, the portion 22 protruding outward from the cutting edge 21 of the opening portion 9 of the covering band 19 is peeled off from the outer peripheral portion 20, Further, it will be understood that the projecting portion 22 acts as a protector for preventing the cut edge 21 from coming into contact with the finger.

In the specific example shown in the drawings, the fixing of the opening type to the can lid may be performed not only by adhesion but also by conventional mechanical fixing by riveting.

The metal material forming the can lid may be a surface-treated steel plate or an aluminum plate, but the present invention is particularly useful for an easily-openable can lid made of a surface-treated steel plate on which a rigid and sharp cutting edge is easily formed. Is. Examples of the surface-treated steel sheet include electrolytic chromic acid-treated steel sheet (TFS), tin-plated steel sheet (tinplate), nickel-plated steel sheet, tin-nickel alloy-plated steel sheet, and aluminum-plated steel sheet, but are not limited to these examples. Metal materials are generally 0.10 to 0.40 mm, especially 0.
It preferably has a thickness of 12 to 0.35 mm.

As the protective coating, any protective coating known per se which exhibits excellent adhesion to the above-mentioned metal material is used. Examples of the paint include thermosetting or thermoplastic resin paints, for example, modified epoxy paints such as phenol / epoxy paints, amino / epoxy paints, and epoxy / ester paints; for example, vinyl chloride-vinyl acetate copolymers, vinyl chloride-acetic acid. Partially saponified vinyl copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, epoxy modified-,
Epoxy amino modified-or epoxy phenol modified-
Vinyl or modified vinyl paints such as vinyl resin paints; acrylic resin paints; oil paints; alkyd paints; polyester paints; synthetic rubber paints such as styrene-butadiene copolymers are used.

A typical primer paint with excellent adhesion and corrosion resistance is a phenol-epoxy paint that consists of a resol-type phenol-aldehyde resin derived from various phenols and formaldehyde, and a bisphenol-type epoxy resin. In particular, it is a coating material containing a phenol resin and an epoxy resin in a weight ratio of 90:10 to 5:95. This paint is also excellent in workability, and has an advantage that the score-processed portion has good corrosion resistance even when subjected to score processing. This type of paint is
It also has excellent adhesion to polyamide adhesives used for fixing tabs.

Other representative examples of protective coatings with excellent adhesion and corrosion resistance are:
It is a vinyl chloride copolymer resin paint having a polar group. This paint contains a polar group such as a carboxyl group, an acid anhydride group and an epoxy group at a concentration of 50 to 2000 mmol per 100 g of resin, and acrylic acid, methacrylic acid,
Contains a resin obtained by copolymerizing maleic anhydride, hydroxy-propyl or ethyl ester of acrylic acid or methacrylic acid, glycidyl acrylate (methacrylate), etc., with other comonomers such as vinyl acetate, and vinyl chloride, if necessary. It is a paint that does. The hydroxyl group can be supplied by saponifying vinyl acetate units in the copolymer, and the epoxy group can be supplied by modifying the copolymer with an epoxy resin or an epoxyphenol paint.

Needless to say, these coating films may have a single-layer structure or a multi-layer structure such as a combination of a base coat and a top coat.

Furthermore, it is of course possible to print on the base coat and then apply a finishing varnish on it.

The thickness of the coating film is not particularly limited as long as the above-mentioned object is achieved, but generally speaking, it is preferably in the range of 0.2 to 30 μm, particularly 1 to 20 μm.

The opening tab may be formed of the same or different material as the material forming the can lid. For example, it may be formed of a light metal plate such as aluminum or an aluminum alloy, or may be formed of a surface-treated steel plate. Further, as long as it has sufficient rigidity, it may be formed of a plastic material.

When the opening tab is fixed with a thermoplastic adhesive, a resin containing an amide repeating unit and / or an ester repeating unit is preferable, and a homo or co-polymer having a melting point or a softening point of 50 to 300 ° C., particularly 80 to 270 ° C. Polyamide, copolyester or blends of two or more of these are used.

The unsealing score 8 has a residual thickness of 1/8 to 1/2 of the raw plate thickness and an absolute thickness of 0.2 to
It is desirable that it is in the range of 0.9 mm, particularly 0.3 to 0.8 mm.

On the other hand, the second score, which is the can lid-resin coating belt engagement mechanism,
It should have such dimensions that it is possible to fill the resin and engage with each other, and the opening width of the score is 0.03 mm or more, preferably 0.05 mm or more, more preferably 0.07 mm or more,
In addition, it is desirable that the taper angle of the score is 150 degrees or less, particularly 135 degrees or less. In addition, the step size of the rim part or the step part that becomes the engagement mechanism is 0.10 to 1.00 mm, especially
The angle is preferably in the range of 0.15 to 0.60 mm, and the angle formed with respect to the horizontal plane is preferably 20 to 90 degrees, particularly 30 to 85 degrees.

Examples of the resin-coated belt include many elastomers such as soft vinyl chloride resin, ethylene-vinyl acetate copolymer, styrene-butadiene block copolymer, and thermoplastic elastomer such as polyurethane, as well as ethylene-propylene rubber, ethylene-propylene. Rubbers such as diene rubber, styrene-butadiene rubber, nitrile-butadiene rubber, polybutadiene, polyisoprene, butyl rubber may also be used.

The adhesive strength (A) per unit width of the resin-coated band can be set within a certain range by adding a tackifier, for example. As the tackifier, coumarone resin, phenol, terpene resin, petroleum hydrocarbon resin, rosin derivative and the like can be used. Also, the strength (T) per unit width of the resin-coated band can be set within a certain range by selecting the tensile strength and the thickness of the resin-coated band.

These resins are applied to the surface of the can lid in the form of solution, latex, plastisol, organosol or the like. The viscosity of the coating solution is 4000 cp to ensure the filling into the second score.
It is desirable to set it to s or less.

The average thickness of the resin coated band is generally 0, on average in the width direction.
005 to 0.5 mm, particularly 0.01 to 0.30 mm is desirable, and from the viewpoint of protection effect, it is desirable that the outward projection from the score 8 is in the range of 0.005 to 3 mm, particularly 0.01 to 2 mm.

(Effects and Examples of the Invention) The excellent effects of the present invention will be described in the following experiments and examples.

Prior to the description of the experiments and the examples, the method for evaluating the physical properties of the resin-coated band and the method for evaluating the opening property will be briefly described below.

[Evaluation of Opening Property] A case in which the test lid is double-wound with the 211-diameter flange canister, and the contents are filled with dressing tuna, and the flat lid is wound, and the retort treatment is performed at 116 ° C. for 90 minutes. , Evaluation was carried out.

The evaluation was conducted on the following items.

(a) Opening force: The score for opening is compared with an uncoated lid, and the one with the same ease of opening the lid is ○, and the one that is difficult to open is ×.
It was evaluated by.

(b) Safety at the time of opening When the resin-covered strip has the lid opened so as to completely cover the edge of the opening, ○, the edge of the opening was opened without being covered with the resin-coated strip. The thing was evaluated by x.

(c) Corrosion resistance of score part A can with a closed lid is left in an atmosphere of 37 ° C and 80% RH for 30 days, and then opened to observe the corrosion condition of the score, and rust does not appear in the score. The case where there is no rust was evaluated as ○, the case where rust was generated in some places was evaluated as Δ, and the case where significant rust was generated in the entire score was evaluated as X.

[Evaluation of Physical Properties of Resin Coated Band] Physical properties of the can lid before opening of the same lot in which the opening property was evaluated were evaluated.

1. Adhesive strength One end of a resin-coated strip of a specified width applied or formed on the can lid or a resin-coated strip backed by a reinforcing film is peeled off from the coating plate,
A 180 ° peel test was conducted between this end and the coated plate. For the tensile test, an Instron type tensile tester was used, and the measurement was performed at a tensile speed of 1000 mm / min and at room temperature. Each sample was measured 5 times, and the arithmetic mean value thereof was converted into a 1 cm width to obtain the adhesive strength (g / cm).

2. Strength Peel off the resin coating of the specified width applied and formed on the can lid,
This was tested at a pulling speed of 200 mm / min at room temperature. Each sample was measured 5 times, and the arithmetic mean of these was 1
The strength (g / cm) was converted to cm width.

Experiment 1 Epoxy / phenolic paint was applied to both sides of a normal tin-free steel (TFS) plate having a thickness of 0.20 mm so that the thickness after baking would be 5 μm, and baking was performed at 210 ° C. for 10 minutes. This coated TFS plate was molded into a lid for 211 diameter using a press, and then a curling portion was coated with a sealing compound by a conventional method and dried. Then the outer diameter 5 of the lid
The opening score is a circle of 8 mm so that the score remaining thickness / steel plate thickness is 0.23, and the score opening is 0.10 mm and the score taper angle is a circle of 54 mm diameter and concentric with this score. A second score of 130 degrees was formed. A vinyl chloride plastisol compound having the following composition was applied to both score portions of the lid material thus obtained by a rotary lining method using a nozzle lining device, and then heated at 200 ° C. for 2 minutes.

Plastisol composition: (parts by weight) Vinyl chloride resin 100 parts Tributyl acetyl citrate 60 parts Epoxidized soybean oil 60 parts Rosin pentaerythritol ester 50 parts The thickness of the resin-coated strip thus obtained is 0.02 mm,
The protruding dimension from the open score to the outside was 1 mm, and both the open score and the second score were covered with the resin without any defect. Finally, using a tab made from a coated TFS board with a thickness of 0.35 mm, nylon 1 so that the distance from the score to the adhesive fulcrum is 6 mm and the width of the adhesive layer at the adhesive fulcrum part is 5 mm.
Adhesion was performed at 220 ° C. using a 2 type film adhesive.

Next, the inner surface of the lid was spray-painted with an epoxy-phenolic paint and baked at 190 ° C. for 4 minutes. Using the thus obtained easily-openable can lid, the openability and the physical properties of the resin-coated band were evaluated.

Experiment 2 A can lid was produced in the same manner as in Experiment 1 except that the epoxy modified vinyl chloride resin coating material was used as the coating material and the vinyl chloride plastisol having the following composition was used as the coating compound.

Plastisol composition: Vinyl chloride resin 100 parts (parts by weight) Epoxidized soybean oil 35 parts Experiment 3 In the above Experiment 1, the same epoxy-phenolic paint as in Experiment 1 was used as the paint, and salt Piblastisol having the following composition was used as the coating compound. A can lid was manufactured in the same manner as in Experiment 1 except that the thickness of the resin-coated band was 0.01 mm.

Plastisol composition: Vinyl chloride resin 100 parts (parts by weight) Acetyl citrate tributyl 60 parts Epoxidized soybean oil 60 parts Rosin pentaerythritol ester 70 parts Experiment 4 In the above Experiment 1, the same epoxy / phenolic paint as in Experiment 1 was used. Was used, and a can lid was manufactured in the same manner as in Experiment 1 except that salt piblastisol having the following composition was used as a coating compound.

Plastisol composition: Vinyl chloride resin 100 parts (parts by weight) Epoxidized soybean oil 35 parts Experiment 5 In the above Experiment 1, the same epoxy-phenolic paint as in Experiment 1 was used as a paint, and a butadiene-acrylonitrile copolymer was used as a coating compound. A can lid was manufactured in the same manner as in Experiment 1 except that a solution consisting of 100 parts by weight and 200 parts by weight of toluene / methyl ethyl ketone was used and dried for 6 minutes at a temperature of 54 ° C.

The above results are shown in Table 1.

From these results, it is found that satisfying the formulas (1), (2) and (3) is important in terms of easy opening, safety and corrosion resistance of the score part.

Example 1 An epoxy / phenolic coating was applied to both sides of a normal tin-free steel (TFS) plate having a plate thickness of 0.20 mm so that the thickness after baking was 5 μm, and baking was performed at 210 ° C. for 10 minutes. This coated TFS plate was molded into a lid for 211 diameter using a press, and then a curling portion was coated with a sealing compound by a conventional method and dried. Next, a stepped portion having a diameter of 53 mm from the center of the lid and having an angle of 40 ° with respect to a horizontal plane having a height of 0.35 mm was formed inside the portion to be processed with the opening score. Next, an opening score was formed on the outer surface of the lid in a circular shape having a diameter of 58 mm and being concentric with the step so that the score remaining thickness / steel plate thickness was 0.23. A vinyl chloride plastisol compound was applied to the score portion and the step portion of the thus obtained lid material by a rotary lining method using a nozzle lining device, and then heated at 200 ° C. for 2 minutes. The thickness of the resin-coated band thus obtained was 0.03 mm, and the outward protruding dimension from the opening score was 2 mm,
The resin coating was evenly applied from the opening score to the step. Finally, as in Example 1, a coated TFS tab and a nylon 12 film adhesive were used to bond at 220 ° C.,
The tab was adhesively fixed to the lid. Further, the inner surface was corrected, and the opening property and the physical properties of the resin-coated band were evaluated using the obtained easily-openable can lid. The results are shown in Table 2.

According to this result, a step portion having a predetermined shape is provided inside the opening score of the can lid, the resin coating covers the step portion, and the physical properties of the resin coating band are within a specific range. In this case, it was possible to hit the opening without any injury to the hand and to perform it safely and with a low force. Further, since the score portion is safely covered with the resin coating, a container having excellent corrosion resistance was obtained.

Example 2 An epoxy / phenolic coating was applied to both sides of a normal tin-free steel (TFS) plate having a plate thickness of 0.20 mm so that the thickness after baking was 5 μm, and baking was performed at 210 ° C. for 10 minutes. This coated TFS plate was molded into a lid for 211 diameter using a press, and then a curling portion was coated with a sealing compound by a conventional method and dried. Next, a stepped portion having a diameter of 53 mm, a height of 0.35 mm, and an angle of 40 ° with the horizontal plane was formed from the center of the lid inside the portion where the opening score was to be processed. Next, an opening score was formed on the outer surface of the lid in a circular shape having a diameter of 58 mm and being concentric with the step so that the score remaining thickness / steel plate thickness was 0.23. Further, a second score having a diameter of 55 mm and a score opening angle of 0.10 mm and a taper angle of 130 degrees was formed concentrically with this score.

A vinyl chloride plastisol compound was applied to the score portion and the step portion of the thus obtained lid material by a rotary lining method using a nozzle lining device, and then heated at 200 ° C. for 2 minutes. The thickness of the resin-coated band thus obtained was 0.10 mm, the outward protruding dimension from the opening score was 1.5 mm, and the resin coating was evenly applied from the periphery of the opening score to the step portion. Finally, the coated A1 tab and a nylon 12 type film adhesive were adhered at 220 ° C., and the tab was adhered and fixed to the lid. Further, the inner surface was corrected to obtain an easily-openable can lid.

The resin coating strip of the easily-openable can lid thus obtained had an adhesive strength of 1000 g / cm and a strength of 500 g / cm.

The easily-openable can lid of this example was double-wound with a 211-diameter flange can body, then filled with tuna oil pickled as a content, and after the flat lid was wound, a retort treatment was performed at 116 ° C. for 90 minutes.
The following evaluations were performed on these easily-openable can lids.

[Drop Test] 1000 cans of this example were dropped from the height of 1 m onto the linoleum floor sideways. The number of peeling cans from the lid of the resin coating was checked.

[Transportation Test] The cans of this example were stored in 50 cases each containing 48 cans, and these cartons were mixedly loaded on a truck flight, and the Tokyo-
I made a round trip between Kagoshima. The number of peeling cans from the lid of the resin-coated band was examined.

Table 3 shows the number of peeled cans from the lid of the resin-coated band before and after the drop and transportation test.

Comparative Example For comparison, as shown in FIG. 3-A, easy-opening was performed in the same manner as in Example 2 except that the PVC plastisol compound was applied to the opening score and the second score and not applied to the step portion. A sex lid was manufactured.

This easily openable lid was evaluated in the same manner as in Example 2 and is shown in Table 3.

Thus, the easily openable lid of the present embodiment in which the step portion having the predetermined shape is provided inside the opening score of the can lid and the resin coating covers the step portion is the resin even after the dropping or the transportation test. The covering band was kept fixed to the lid, and there was no hand injury upon opening, and it was possible to open safely.

[Brief description of drawings]

FIG. 1 is a top view of an easily-openable can lid of the present invention, FIG. 2 is a side sectional view taken along line AA ′ of the can lid of FIG. 1, and FIG. 3A is for opening a resin coating. Enlarged sectional view of the lid provided with only the score and the second score. FIG. 3-B is a sectional view taken along the line AA in FIG. 2 of the lid of the present invention, and FIG. 4 is a diagram for explaining a stage in the middle of opening. 1 ... metal, 2 ... metal material, 3a ... outer surface protective coating,
3b ... Inner surface protective coating, 4 ... Outer circumferential groove, 5 ...
... annular rim portion, 6 ... panel portion, 7 ... sealing compound layer, 8 ... score, 9 ... portion to be opened, 10 ... opening tab, 11 ... score tearing tip, 12 ... ... Gripping part (ring), 13 ... Support point part, 1
4 ... U-shaped cut, 15 ... Connection part, 16 ... Thermoplastic resin adhesive layer, 17 ... Second score, 18 ... Rim part or step part, 19 ... Cutting edge protection resin Coated belt, 2
0 ... outer peripheral portion, 21 ... cutting edge, 22 ... part protruding outward from the cutting edge.

Claims (2)

[Claims] 1. A score for opening, which defines a portion to be opened provided on a can lid, a tab for opening, which is provided on a portion to be opened, and a score between the portion to be opened and a peripheral portion of the can lid. An easily-openable can lid consisting of a resin coating strip for protecting the cutting edge provided so as to straddle the upper part of the can lid. A rim portion or a step portion is provided inside the opening score of, and a resin coating band is provided so as to cover the rim portion or the step portion. In the formula, A is the adhesive strength per unit width (cm) between the resin coating band and the lid, T is the strength per unit width (cm) of the resin coating band, and C is a constant (900). is there. The resin-covered band that satisfies the above condition, and when opening, peeling occurs between the resin-covered band outside the opening score and the peripheral part of the can lid, and the cut edge of the opening is covered with the resin-covered band. Easy-to-open can lid designed so that 2. The resin coating is provided with a relatively small width from the upper part of the score to the peripheral part of the can lid, and is provided with a relatively wide width to reach the engaging mechanism from the upper part of the score to the part to be opened. The easily-openable can lid according to claim 1.