JP2012192972A - Metal container lid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal container lid having a liner bonded and fixed to the inside via an adhesive paint layer and a nonadhesive area formed to set the circumferential edge of the liner as a free end without forming any special layer such as a masking layer on the adhesive paint layer.SOLUTION: The metal container lid includes a sheet metal cap shell having a circular top surface wall 7 and a skirt wall 9, and a liner 5 disposed in the inner surface of the top surface wall 7. An adhesive area X and a nonadhesive area Y are formed in the inner surface of the top surface wall 7, and the liner 5 is in tight contact with the adhesive area X and the nonadhesive area Y. The adhesive area X includes an adhesive paint layer 30 formed in the inner surface of the top surface wall, and the nonadhesive area Y is formed by irradiating the adhesive paint layer 30 with laser light.

Description

  The present invention relates to a metal container lid, and more specifically, a metal sheet shell having a circular top wall and a cylindrical skirt wall depending from the periphery of the top wall, and an inner surface of the circular top wall of the shell. The present invention relates to a metal container lid provided with a synthetic resin liner disposed.

  Metal container lids obtained by forming and processing metal thin plates such as aluminum and steel are widely used as lids for rigid containers such as glass bottles and metal containers. Such a metal container lid includes a thin metal plate shell having a circular top wall and a cylindrical skirt wall depending from the peripheral edge of the top wall. In order to ensure the sealing performance, a synthetic resin liner is provided. That is, when the container lid is attached to the container mouth, a highly flexible synthetic resin liner is brought into close contact with the upper end portion of the container to ensure the sealing performance.

  The above-mentioned synthetic resin liner is arranged by dropping molten resin onto the inner surface of the top wall of a metal sheet shell formed into a cap shape, and compressing the dropped resin melt in the shell. Is done. In this case, an adhesive paint layer is formed in advance on the inner surface of the thin metal shell, and the resin for liner formation is bonded and fixed to the inner surface of the top wall.

In the synthetic resin liner arranged as described above, the entire surface thereof is bonded and fixed to the metal thin plate shell, but recently, the peripheral portion thereof is not bonded to the metal thin plate shell (top wall). Has been proposed (see, for example, Patent Document 1).
That is, the metal container lid is provided with a synthetic resin liner, which is then placed on the container mouth, and the peripheral edge of the top wall and the upper end of the skirt wall are attached to the outer surface of the container mouth using an appropriate jig. Then, the screw on the outer surface of the container mouth is transferred to the skirt wall, so that the screw is formed on the container lid and the container lid is attached to the container mouth at the same time. When the metal container lid is attached to the container mouth in this manner, the peripheral edge of the top wall and the upper edge of the skirt wall should be such that the peripheral edge of the liner is not bonded and fixed to the metal thin plate shell (top wall peripheral edge). When caulking along the outer surface of the container mouth, the peripheral edge of the liner can be easily deformed and closely attached so as to wind up the upper end of the container mouth, and high sealing performance can be easily secured. This is because the degree of freedom of the liner at the close contact portion with the portion is high, so that the resistance to impact is high, and the sealing breakage due to the impact can be effectively prevented.

JP 2005-153974 A

  By the way, in order to bond and fix the synthetic resin liner to the inner surface of the top wall of the metal thin plate shell and at the same time to make the peripheral portion of the liner non-adhering to the inner surface of the top wall, the metal thin plate before being punched into a circular shape An adhesive paint layer is provided over the entire inner surface of the liner, and then a masking layer is formed in a portion corresponding to the peripheral portion of the liner, and then bent and drawn into a lid shape. The resin melt is dropped and compression molding is performed to form a liner.

  When producing a metal container lid in which the peripheral edge of the liner is non-adhered to the inner surface of the top wall as described above, the masking layer peels off at the stage from the masking layer formation to the liner molding. The object of improving the sealing performance by making the peripheral portion non-adherent may not be sufficiently achieved. That is, the masking layer is not very poor in adhesiveness to a resin or the like, but an adhesive component (for example, acid-modified olefin resin) that improves the adhesiveness to the liner is used for the adhesive coating layer that is the base of the masking layer. In addition, various waxes and the like are blended as lubricants in order to improve the ease of opening by reducing the friction coefficient. For this reason, inconveniences such as peeling of the masking layer from the adhesive coating layer during a severe molding process after the masking layer is formed easily occur.

  The masking layer is formed, for example, by applying a predetermined ink (referred to as masking ink) and curing it. As such a masking ink, the adhesion to the adhesive paint layer is enhanced. Therefore, an oil-modified alkyd ink in which an oil and fat component (glycerin fatty acid ester) and the like are blended is preferably used. Such a masking ink has a characteristic oily odor. Therefore, when the masking ink is attached to the mouth of a container filled with a predetermined content, the flavor of the content is impaired.

  Accordingly, an object of the present invention is a metal container lid in which a synthetic resin liner is bonded and fixed inside via an adhesive paint layer, and a special layer such as a masking layer is formed on the adhesive paint layer. Without providing the metal container lid in which the non-adhesion area | region for making the peripheral part of this liner into a free end is formed.

According to the present invention, a metal thin plate shell having a circular top wall and a cylindrical skirt wall depending from the periphery of the top wall, and a synthetic resin liner disposed on the inner surface of the circular top wall of the shell are provided. In the metal container lid that
An adhesive region and a non-adhesive region are formed on the inner surface of the circular top wall, and the liner is in close contact with the adhesive region and the non-adhesive region,
The adhesive region is formed of an adhesive paint layer formed on the inner surface of the circular top wall, and the non-adhesion region is formed by laser light irradiation on the adhesive paint layer. A container lid is provided.

In the metal container lid of the present invention,
(1) The adhesive paint layer remains in the non-adhesive region, and interface peeling occurs between the adhesive paint layer and the circular top wall in the non-adhesive region,
Or (2) the adhesive paint layer remains in the non-adhesive region, and the liner is non-adhered to the surface of the adhesive paint layer in the non-adhesive region;
Is preferred.

  In the present invention, the synthetic resin liner is formed by dropping onto the adhesive coating layer formed on the inner surface of the top wall and compression-molding the molten resin in the metal sheet shell. That is, this adhesive paint layer is an adhesive region, and at this portion, the liner is adhesively fixed to the inner surface of the top wall, and when this container lid is attached to the container mouth, the liner Is held in close contact with the upper end of the container mouth without falling off, and effectively functions as a sealing material.

  In addition, a non-adhesive region is formed together with the above-mentioned adhesive region in the portion of the metal thin plate shell to which the liner is applied. In this region, the liner is not bonded and fixed, and has a high degree of freedom. Have. Therefore, for example, by arranging a non-adhesive region at the peripheral edge of the circular top wall, the liner can be easily wrapped around the upper end of the container mouth when the container lid is caulked with the container lid. It can be deformed into close contact, and high sealing performance can be easily secured. Further, the degree of freedom of the liner at the close contact portion with the container mouth portion is high, and therefore, the resistance to impact is high, and sealing breakage due to impact can be effectively prevented.

  Furthermore, a metal container lid having a structure in which a breaking score is provided from the skirt wall to the peripheral edge of the top wall is known. In such a cap, no screw is formed, and the score is broken by holding a grip ring connected to the skirt wall, and the container lid is removed from the container mouth. Even in such a container lid, a non-adhesive region is formed at a position slightly inside to outside of the score of the circular top wall, so that when opening, the grip ring is lifted to break the score, and the container lid is Upon removal from the container, the liner is lifted with a tear surrounded by the score so that the skirt outside the score can be easily removed from the container.

The most characteristic feature of the present invention is that the non-adhesion region is formed by irradiating the adhesive coating layer with laser light. The adhesive paint layer is altered or removed by the irradiation of the laser beam, and the adhesive property of the adhesive paint layer to the liner or the metal thin plate shell (the inner surface of the top wall) is lost, thereby forming a non-adhesive region. is there.
That is, in the present invention, it is not necessary to provide a special layer such as a masking layer on the adhesive paint layer in order to form the non-adhesion region. Therefore, it is possible to reliably prevent inconveniences such as peeling of the masking layer and deterioration of flavor caused by the oily odor caused by the masking layer, and to fully provide the advantage of forming a highly flexible part (such as improved sealing performance) on the liner. It can be demonstrated.

The half cross section side view which shows the state which mounted the example of the container lid of this invention in the container opening part. The partially expanded schematic sectional drawing of FIG. The fragmentary sectional view which shows the process of winding up the container lid of FIG. 1 to a container opening part. The half cross section side view which shows the state by which the container lid shown in FIG. 1 was wound around the container opening part. The partially expanded schematic sectional drawing of FIG. The top view which shows the adhesion | attachment state of the top | upper surface wall inner surface of a container lid of FIG. 1, and a liner. The figure which shows the pattern of the non-adhesion area | region formed by laser beam irradiation.

  1 and 2, a metal container lid according to the present invention includes a metal thin plate shell (hereinafter also referred to as a cap shell) 3 and a synthetic resin liner 5 provided in the shell 3. It consists of and.

The cap shell 3 has a circular top wall 7 and a substantially cylindrical skirt wall 9 that hangs from the periphery of the top wall 7, and the material thereof is not limited as long as an appropriate strength is ensured. For example, it may be formed from a thin metal plate such as aluminum or an aluminum alloy. However, from the viewpoint of ensuring particularly excellent drop impact resistance, for example, an aluminum base having a thickness of about 0.22 to 0.26 mm is used. It is preferably formed from an alloy thin plate, and its tensile strength is preferably in the range of 200 to 230 N / mm ² .

  As the synthetic resin liner 5, a synthetic resin having appropriate cushioning and sealing properties, for example, an olefin resin elastomer such as polyethylene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, soft vinyl chloride, etc. System resin is used. Such a synthetic resin liner 5 is formed by embossing by dropping a melt of a resin for forming a liner into the cap shell 3 and is adhesively fixed to the inner surface of the top wall 7 of the cap shell 3.

  As is clear from FIG. 1, the lower end of the skirt wall 9 is bulged outward in the radial direction, and the bulged lower end portion is tampered with a plurality of breakable bridges 11. (TE) The skirt 13 is continuous.

  A substantially central portion of the skirt wall 9 is a screw forming region 15 in which a screw is formed by tightening described later, and an annular groove 17 is formed at the upper end of the screw forming region 15. The annular groove 17 is for introducing a jig for winding.

A knurl 19 is formed above the annular groove 17, whereby the grip performance of the container lid is enhanced, and can be easily opened or closed.
A plurality of arc-shaped slits 20 extending in the circumferential direction are formed at the upper end of the knurl 19 at appropriate intervals. This arc-shaped slit 20 is used for degassing when the internal pressure of the container rises abnormally due to the content decay or the like, degassing when opening a container lid attached to an internal pressure container such as a carbon dioxide beverage container, or cleaning. It is provided to introduce water.

  As shown in FIGS. 1 and 2, the metal container lid is put on the container mouth portion 70, and is wound on the container mouth portion 70 by the tightening process shown in FIG. 4 and FIG. 5, the container mouth portion 70 is fixed to the container mouth portion 70, and the container mouth portion 70 is sealed.

  The container mouth portion 70 (container) is made of metal, glass, hard resin, or the like, and a metal one is illustrated in the example shown in the figure. As shown in FIGS. 1 to 5, a curl portion 71 is formed at the upper end of the container mouth portion 70, a screw 73 is formed on the side surface, and a jaw portion 75 is formed below the screw 73. ing.

  As described above, the synthetic resin liner 5 is formed by supplying a synthetic resin melt to the inner surface of the top wall 7 and embossing the melt into a required shape, and can be formed conveniently. . The liner 5 in the illustrated embodiment is composed of a relatively thin circular central portion 5a and a relatively thick annular peripheral portion 5b, and the central portion of the annular peripheral portion 5b is a slightly recessed recess. .

  As shown in FIG. 1, in the state where the container lid (shell 3) is put on the container mouth portion 70 in order to wind it around the container mouth portion 70, the upper end (curl portion 71) of the container mouth portion 70 is described above. The concave portion of the annular peripheral edge portion 5 b of the liner 5 faces, and the lower end of the TE bottom portion 13 of the container lid is located below the jaw portion 75 of the container mouth portion 70.

That is, as shown in FIG. 1, winding is performed as shown in FIG. 3 in a state where the container lid is put on the container opening 70. That is, the container lid placed on the container mouth part 70 is pressed against the upper end of the container mouth part 70 by the outer pressing tool 77 and the upper end part of the skirt wall 9 is caulked from the peripheral part of the top wall 7 (winding). At the beginning of tightening), the screw forming roller 79 is introduced into the annular groove 17 of the container lid, and then the roller 79 is rotated along the male screw 73 of the container mouth portion 70 while pressing the skirt wall 9 of the container lid. Then, the female screw 25 that engages with the male screw 73 of the container neck 70 is formed in the screw forming region 15 of the skirt wall 9.
On the other hand, the lower end of the TE skirt 13 of the container lid is pressed against the lower side of the chin 75 of the container mouth 70 by the hem winding roller 80, thereby deforming along the lower side of the chin 75. It becomes.

  As shown in FIG. 4, the metal container lid made of the shell 3 is fastened and fastened to the container mouth part 70 by the above-described tightening process, and the container mouth part 70 (curl part 71) has an upper end and an outer peripheral part. When the annular peripheral edge portion 5b of the liner 5 is in close contact, the container mouth portion 70 is sealed. In this state, the skirt wall 9 is screw-engaged with the outer surface of the container mouth portion 70, and the lower end of the TE skirt portion 13 is fixed to the lower side of the jaw portion 75 of the container mouth portion 70.

  The container lid fastened and fixed to the container mouth part 70 is rotated in the direction of opening, so that the skirt wall 9 rises and is removed from the container mouth part 70. The lower end of 13 is engaged with the lower side of the jaw portion 75 of the container mouth portion 70, so that its rise is restricted. As a result, the bridge 11 is broken and the TE skirt portion 13 is separated from the skirt wall 9. . Therefore, the TE skirt 13 is cut off from the container lid removed from the container mouth part 70, whereby the fact of opening can be recognized.

  By the way, as shown in FIG. 4, a portion of the top edge of the top wall 7 that extends from the peripheral edge of the top wall 7 to the upper end of the skirt wall 9 becomes a curled portion 71 of the container mouth 70 by winding the container mouth 70. As a result, the annular peripheral edge 5b of the liner 5 is bent together with the top wall 7 and the skirt wall 9 so as to be brought into close contact with the curled portion 71, thereby ensuring good sealing performance. Is done.

  Since the annular peripheral edge portion 5b of the liner 5 is in close contact with the curled portion 71 as described above, the annular peripheral edge portion 5b is held non-adhered to the top wall 7. In other words, the circular central portion 5a of the liner 5 is firmly bonded and fixed to the inner surface of the top wall 7 to effectively prevent its dropout and displacement, but the annular peripheral edge portion 5b is not bonded to the inner surface of the top wall 7. It is held in a state (in short, a free state). When the annular peripheral portion 5b of the liner 5 is held in a free state, the annular peripheral portion 5b of the liner 5 is deformed due to deformation of the peripheral portion of the top surface wall 7 and the upper end portion of the skirt wall 9 when winding as described above. This is because it is possible to follow smoothly and closely adhere to the curled portion 71 to ensure good sealing performance. Further, it is more effective in terms of impact resistance and sealing when the annular peripheral portion 5b of the liner 5 is held in a free state, and even when subjected to a large impact, the skirt wall 9 and the top wall 7 are not affected. The adhesion with the curled portion 71 can be maintained without being affected by the applied vibration or deformation.

Accordingly, referring to FIG. 6 showing the adhesion between the inner surface of the top wall 7 and the liner 5 together with the partially enlarged sectional views of FIGS. 2 and 5, the top wall on which the liner 5 is provided in the container lid of the present invention. 7, the central portion is an adhesion region X, and the peripheral portion is a non-adhesion region Y. That is, the adhesive paint layer 30 is formed on the inner surface of the top wall 7, thereby forming the adhesion region X, but the adhesiveness of the adhesive paint layer 30 is lost at the peripheral portion thereof. Thus, a non-adhesive region Y is formed. A liner-forming resin melt is dropped on the inner surface of the top wall 7 in which such an adhesive region X and non-adhesive region Y are formed, and embossing is performed, so that the thin circular central portion 5a of the liner is removed. The region that slightly entered the annular peripheral portion 5b was firmly adhered and fixed to the adhesive region X, and the annular peripheral portion 5b outside the adhesive region X was held non-adhered to the inner surface of the top wall 7 in the non-adhesive region Y. The liner 5 is formed, and the annular peripheral portion 5b of the liner 5 is brought into close contact with the curled portion 71 of the container mouth portion 70 by the above-described winding process, thereby forming a seal.
2 and 5, the adhesive paint layer 30 is shown, but in other figures, the adhesive paint layer 30 is omitted.

The adhesive paint layer 30 that forms the adhesive region X as described above is formed of a known adhesive paint.
Such adhesive paints include, for example, phenolic resins, amino resins, and isocyanate resins as curing agents in film forming resins such as epoxy resins, polyester resins, and vinyl resins, and start radical polymerization of these resin components as appropriate. It is dissolved or dispersed in an organic solvent such as alcohols and ketones together with an agent and the like, and an acid-modified olefin resin is blended as an adhesive component in order to improve adhesion. Examples of the acid-modified olefin resin include polyolefins such as polyethylene and polypropylene, unsaturated carboxylic acids or anhydrides thereof such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid, 5- Examples thereof include norbornene-2,3-dicarboxylic acid, maleic anhydride, citraconic anhydride, itaconic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, tetrahydrophthalic anhydride and the like.
The adhesive paint layer 30 is formed on the inner surface of the thin metal plate before forming into the cap shell 3 (having a thickness of about 0.5 to 10 μm). Therefore, the skirt together with the inner surface of the top wall 7 is used. It is formed on the entire inner surface of the cap shell 3 including the inner surface of the wall 9. Therefore, the above-mentioned adhesive paint is typified by petroleum synthetic wax, natural wax made of fatty acid ester, etc., in order to improve the slipping property of the container mouth portion 70 with respect to the screw 73 and to improve the openability. A lubricant component is also included.

  By the way, in the past, the adhesive region X and the non-adhesive region Y were formed by providing a masking layer on the adhesive coating layer 30, but such a masking layer has very poor adhesion to the adhesive coating layer 30. In the stage before forming the liner 5, it is easy to peel off, and therefore, there is a possibility that the peripheral portion of the liner 5 cannot be reliably held in a non-adhered state.

  However, according to the present invention, the non-adhesive region Y is formed by irradiating the adhesive paint layer 30 with laser light. That is, when the non-adhesive region Y is formed by providing a special layer such as a masking layer on the adhesive paint layer 30, adhesion failure between the masking layer and the adhesive paint layer 30, peeling of the masking layer, etc. In the present invention, since the non-adhesive region Y is formed by irradiating the adhesive coating layer 30 with laser light in the present invention, there is no problem of delamination or the like, and the non-adhesive region Y is surely obtained. Can be formed.

  In the non-adhesion region Y formed by laser light irradiation, there are three patterns shown in FIG. 7 according to the irradiation energy density of the laser light.

  The pattern shown in FIG. 7A is a case where the irradiation energy density is increased and the laser beam is irradiated. In this case, the resin is thermally decomposed at the portion irradiated with the laser beam (laser ablation), The adhesive paint layer 30 disappears and the non-adhesion region Y is formed.

  The pattern shown in FIG. 7B is a case where the laser beam is irradiated with the irradiation energy density being medium. Laser ablation of the adhesive coating layer 30 proceeds from the surface side, and only the upper layer portion disappears. The adhesive paint layer 30 itself remains. In this case, the adhesive component (for example, acid-modified olefin resin) blended in the adhesive coating layer 30 and moving to the surface is decomposed or altered, and the remaining adhesive coating layer 30 adheres to the liner 5. The property disappears and the non-adhesive region Y is formed. Further, in this case, due to the loss of adhesiveness, the adhesion between the adhesive coating layer 30 and the shell 3 (top wall 7) is greatly reduced, and in some cases, interfacial peeling occurs.

The pattern shown in FIG. 7C is a case where the irradiation energy density is further lowered and the laser beam is irradiated, and laser ablation of the adhesive paint layer 30 does not occur, and the adhesive paint layer 30 remains as it is. ing. In this case, the adhesion of the adhesive coating layer 30 to the liner 5 is maintained on the surface, but the adhesion between the adhesive coating layer 30 and the shell 3 (top wall 7) is remarkably reduced, and its 180 degree peel strength ( JIS K6850) is 0.5 N or less, and preferably interface peeling occurs. That is, under the low output condition, when laser light is irradiated, heat is easily dissipated on the surface side of the adhesive coating layer 30, so that neither alteration nor decomposition occurs, but the interface side with the shell 3 (top wall 7). In this case, since the influence of the reflection of the laser beam and the heat are not easily dissipated, the paint constituting resin or the adhesive component in the adhesive paint layer 30 is altered. As a result, the adhesive paint layer 30 and the shell 3 (the top wall 7) The adhesion will be significantly reduced.
In such a pattern, the liner 5 is adhered to the adhesive coating layer 30 in the region irradiated with the laser light. However, when the liner 5 is peeled off, the adhesive coating layer 30 is also peeled off from the shell 3 following the liner 5. It will be. That is, the liner 5 is adhered to the adhesive coating layer 30 in the same manner as the adhesive region X, but is held in an unbonded state with the shell 3 (the top wall 7), and the region irradiated with the laser light is It becomes a non-adhesion area Y.

  In the present invention, the pattern that is particularly preferably employed is the pattern shown in FIGS. 7B and 7C from the viewpoint that the generation of dust resulting from the decomposition of the adhesive coating layer 30 is small, and particularly the pattern shown in FIG. ) Pattern does not generate any dust and is optimal in the present invention.

  The laser beam irradiation energy density can be adjusted by, for example, various means other than by adjusting the laser beam output. For example, the distance between the laser light source (laser oscillator) and the adhesive coating 30 and the laser beam can be adjusted. This can also be done by adjusting the spot diameter. That is, if the distance between the laser light source and the adhesive coating 30 is reduced, the irradiation energy density is increased, and if this distance is increased, the irradiation energy density is decreased. Moreover, if the spot diameter of the laser beam irradiated to the adhesive coating film 30 is reduced, the irradiation energy density is increased, and if the spot diameter is increased, the irradiation energy density is decreased. Therefore, the non-adhesive region Y may be formed with a target pattern by adjusting the irradiation energy density according to the laser light irradiation conditions according to the type of laser source used, the laser light absorption characteristics of the adhesive coating film 30, and the like.

  Further, as can be understood from the above description, in the present invention, the non-adhesion region Y can be formed by irradiation with laser light at a low output level. Any device that exhibits characteristics can be used. For example, in the field of welding and machining, solid-state lasers such as YAG and fiber laser are widely used. However, in the present invention, gas lasers such as carbon dioxide laser and excimer laser can also be used. This is a great advantage from a cost standpoint.

  For example, a commercially available adhesive paint (Toyo Ink, Kansai Paint, DIC Graphics Adhesive Varnish) is applied to the surface of an aluminum plate to form an adhesive coating 30 having a thickness of 4 μm, and a laser oscillator (YAG laser) is used. 7A and 7B by irradiating the laser beam while changing the interval between the laser oscillator and the adhesive coating film 30 with the output fixed at 13 W and the spot diameter fixed at 60 μm (irradiation time 0.5 seconds). It can be confirmed that the non-adhesion region Y is formed in the patterns shown in FIGS.

  That is, when laser light is irradiated with the interval set to 190 mm, the output density is extremely high, and the non-adhesive region Y is formed in the pattern shown in FIG. ) Completely disappeared.

  Further, when the laser beam is irradiated with the interval set to 200 mm, the output density is lowered, and therefore the non-adhesion region Y is formed in the pattern shown in FIG. In the adhesion area Y), the adhesive coating 30 remained, but did not show adhesion to the liner.

  Further, when the laser beam was irradiated with the interval set to 210 mm, the output density was further lowered, and thus the non-bonded region Y was formed in the pattern shown in FIG. That is, the adhesive coating film 30 remains in the laser light irradiation portion (non-adhesion region Y), and this adhesive coating film 30 also showed adhesion to the liner, but the interface peeled off from the aluminum plate. Has occurred.

In addition, the presence or absence of the adhesive coating film 30 in a laser beam irradiation part (non-adhesion area | region Y) can be confirmed by the microscopic observation of the surface, or the reactivity with copper sulfate aqueous solution. For example, when the adhesive coating film 30 remains, the copper sulfate aqueous solution does not react with the aluminum plate, but when it disappears, it reacts with the aluminum plate.
Further, the interfacial peeling between the adhesive coating film 30 and the aluminum plate at the laser light irradiation part (non-adhesion region Y) can be confirmed from the occurrence of swelling in the adhesive coating film 30. That is, it is because swelling occurs due to the gas generated by the alteration of the adhesive coating film 30 at the interface between the adhesive coating film 30 and the aluminum plate.

  In the present invention, formation of the non-adhesion region Y by laser light irradiation to the adhesive coating 30 can be performed at any stage before the formation of the liner 5 in the in-shell mold after the formation of the adhesive coating 30. It is preferable to carry out after forming a metal thin plate into a cap shape.

  That is, the adhesive thin film 30 is formed on the entire inner surface of the metal thin plate, and a printing layer is appropriately formed on the entire outer surface. A non-adhesive region Y is formed by irradiating a laser beam to a predetermined position (the peripheral edge portion of the top wall 7 to which the outer peripheral edge portion of the liner 5 comes into close contact when molded into the cap shell 3) on the inner surface of such a coated metal sheet It is possible to do. However, this coated metal thin plate has a width of about 1 m, for example, and a large number of cap shells 3 are formed from this thin plate by punching, bending drawing or the like. Therefore, when irradiating laser light at the stage before punching, an extremely large laser light irradiation device is used or a large number of laser light irradiation devices are required, resulting in an increase in production cost and maintenance of the device. Will be burdened.

  However, after the coated metal thin plate having the adhesive coating layer 30 formed on the inner surface as described above is punched and the cap shell 3 is formed by bending drawing, laser light is applied to the peripheral portion of the top wall 7 of the shell 3. When the means for forming the non-adhesive region Y by irradiating is applied, a laser beam irradiation device can be arranged on the conveying line of the cap shell 3 to perform laser beam irradiation. For this reason, it is possible to effectively avoid an increase in the size and number of the laser beam irradiation apparatus.

  In the present invention described above, the width of the non-adhesion region Y may be a width corresponding to the annular peripheral portion 5b of the liner 5 described above, as shown in FIG. In general, the inner peripheral side end Y ′ (see FIG. 2) of the non-adhesive region Y is the container mouth portion 70 (curl portion 71). It is preferable to set it so that it is located on the inner circumferential side by about 1 to 10 mm from the inner circumferential side end Z of the inner wall. This is because the liner 5 in this portion is bent and closely adhered to the upper end portion of the container mouth portion 70 to form a sealed portion. When the non-adhesive region occupies the inner side, the annular peripheral edge 5b of the liner 5 hangs downward, and when the container lid is wound around the container mouth, the annular peripheral edge 5b of the liner 5 is the inner peripheral surface of the container mouth. There is a risk of getting caught on the side.

Further, in the above-described example, the cap shell 3 is of a swing opening type, and the female screw 25 is formed on the skirt wall 9 by transfer from the male screw 73 of the container mouth portion 70, and this shell 3 is swung. By removing the screw engagement, the container mouth portion 70 is removed. However, the present invention can also be applied to a non-swiveling metal container lid.
A female screw is not formed in the cap shell of the non-swiveling container lid. For example, as shown in Japanese Patent Laid-Open No. 2002-284219, a relatively short skirt wall is used instead of the female screw. A tension tab is provided at 9, and a pair of breaking scores extend from both ends of the tab toward the top wall, and this score further extends along the peripheral edge of the top wall 9. That is, this type of metal container lid is for removing the container lid (cap shell 3) from the container mouth portion 70 by pulling up the tab and breaking the score. Even in such a type, it is desirable to form the non-adhesive region Y in the peripheral portion of the liner 5 (peripheral portion of the top wall 7) for the reasons described above. An adhesion region Y can be formed. That is, in this case, it is desirable that the score of the top wall 7 is provided so as to be positioned on the non-adhesive region Y so that the liner 5 does not disturb the score breakage due to the pulling up of the tab. is there.

  In the metal container lid of the present invention, since the peripheral edge of the liner for imparting hermeticity is securely held free, its hermeticity is extremely high and impact resistance is high, and hermeticity due to impact is low. Reduction is also effectively prevented.

3: Thin metal shell (cap shell)
5: Synthetic resin liner 7: Top wall 9: Skirt wall 30: Adhesive paint layer 70: Container mouth X: Adhesive area Y: Non-adhesive area

Claims (3)

A metal container lid comprising a thin metal plate shell having a circular top wall and a cylindrical skirt wall depending from the peripheral edge of the top wall, and a synthetic resin liner disposed on the inner surface of the circular top wall of the shell In
An adhesive region and a non-adhesive region are formed on the inner surface of the circular top wall, and the liner is in close contact with the adhesive region and the non-adhesive region,
The adhesive region is formed of an adhesive paint layer formed on the inner surface of the circular top wall, and the non-adhesion region is formed by laser light irradiation on the adhesive paint layer. Container lid.   2. The metal container lid according to claim 1, wherein the adhesive paint layer remains in the non-adhesive region, and interface peeling occurs between the adhesive paint layer and the circular top wall in the non-adhesive region. .   The metal container lid according to claim 1, wherein the adhesive paint layer remains in the non-adhesive region, and the liner is non-adhered to the surface of the adhesive paint layer in the non-adhesive region.

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