JP2006151427A - Threaded can container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the opening torque of a cap of a can container in which a joining stepped part of a joining can barrel is formed on a threaded part. <P>SOLUTION: A threaded can container comprises a cylindrical container barrel portion having an overlapped joining part 16 with a stepped part 15 formed on a side face, and a container mouth part 5 with a thread and a curl part formed on an opening end of the container barrel portion. A bottom lid is seamed at a lower end of the barrel portion, a cap with a resin-made sealing liner added to an inner surface side of a top plate part covers the container mouth part, and the cap is seamed and sealed to the container mouth part so as to form a screw groove in a skirt part of the cap to the thread. The thread is formed in the direction in which the cap 7 is opened from the upper side to the lower side of the overlapped stepped part with respect to the joined part 16. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is provided with a screw in which a cap having a resin sealing liner attached to the inner surface side of the top plate portion of a metal shell is put on the container mouth portion and the cap is attached to the container mouth portion by roll-on molding. The present invention relates to a can container, and more particularly, to a can container with a screw having a joining portion obtained by polymerizing a metal plate on a side surface of a body portion of the can container, and having a bottom lid wound around the lower end of the body portion.

  Conventionally, as containers for foods such as glass bottles, packaging containers with a large opening for taking out contents and having a reseal function are known, and the contents are taken out and transferred to another container. Because it is easy to change, it is used to pack contents such as instant coffee, cream powder, jam, corn soup, sauce, and fruit wine with pulp. In addition, when beverages such as coffee, tea, and green tea are used as contents, wide-mouth containers are widely used because the scent can be enjoyed when the lid is opened.

  Recently, a sealing liner made of resin is attached to the inner surface side of the top plate portion of the shell, which is a metal cap, and the cap is screw-wound by roll-on molding by covering the cap with the cap. Threaded can containers to be attached to are distributed and sold. Both the cap and the container body are made of metal, which not only provides excellent light-shielding and breathability for the contents, but also has the convenience of being resealed and carried, and is not as heavy as a glass bottle. It has been highly appreciated for its weight, and it has been on the market a lot.

  In addition, such a threaded can container is available in various sizes, and a variety of container mouth sizes are available. As described above, a new one that takes advantage of the wide opening is utilized. A type of packaging container is described in, for example, Patent Document 1, and this type of wide-mouthed screw-type can container is known.

  Normally, when a cap is attached to a resealable container, a cap (sometimes referred to as a cap shell) that is not threaded on a skirt (or cylinder) hanging from the outer periphery of the top plate is used as a container mouth. A thread-forming roll is pressed from the outside of the skirt portion by a conventionally known roll-on capping device to form a thread groove that matches the thread (male thread portion) of the container mouth, and a cap. The shell is tightened and thus the cap is attached to the container mouth. When roll-on molding such a metal cap, with the cap shell placed over the container mouth, the corner between the top plate of the cap shell and the skirt is deformed inward, For example, Patent Document 2 describes that the sealing of the container mouth portion by the liner is ensured by biting the container mouth portion into the sealing liner attached to the inner surface of the top plate portion. As has been known, it has been conventionally known.

In addition, in a large wide-mouthed reseal can with an inner diameter of 30 mm or more in the opening, the top surface height of the curled portion becomes uneven due to screw molding, and variation tends to occur. It has also been conventionally known to form a curled portion again after forming a screw portion (see, for example, Patent Document 3).
Japanese Patent Laid-Open No. 2003-321039 JP 2001-213417 A JP 2003-251425 A

  By the way, in the wide-mouth reseal can described in the above-mentioned patent document, the container mouth portion is formed by forming a pre-curl portion at the upper end of the can body, forming a screw portion, and then forming the curl portion again. The opening torque could be reduced by the amount that the variation in the top height of the surface was reduced. However, for example, a wide-mouth reseal can using a three-piece can can body having a joint on the side of the can body, such as a welded can body, is required to be easier to open.

  That is, when roll-on molding with a cap placed on the container mouth, the cap shell skirt is deformed along the thread (male thread) formed on the container mouth. The step portion of the formed joint portion is in a state of being transferred to the cap, and the step mark is formed on the cap. Then, the cap is attached to the container mouth portion in a state where the stepped portion of the thread in the container mouth portion and the cap are formed so that the step marks face each other. For this reason, when opening the cap, if the stepped trace of the cap gets over the stepped portion of the joint, the stepped trace of the cap and the stepped portion of the joined portion start turning the cap when opening the cap. It has been found from applicants' various experiments that it becomes one of the causes for increasing the torque.

  Also, when opening over the stepped portion of the joint portion, the coating film covering the edge portion of the stepped portion is peeled off or the cap inner surface coating is displaced by the edge portion, resulting in resin residue, It has also been found that there is a problem of adhering to the contents and mixing into the contents, and at the time of re-plugging, there is a risk of being caught in the seal part and impairing the sealing performance.

  An object of the present invention is to solve the above-described problems. Specifically, it is possible to improve the sealability and openability of the container mouth by the cap, and to apply the coating at the time of opening. An object of the present invention is to provide a threaded can container that prevents generation of film residue and prevents foreign matter from adhering to a drinking mouth.

  In order to achieve the above object, the invention of claim 1 is directed to a cylindrical container body having a lap joint having a stepped portion formed on a side surface, and a thread and a curl at the open end of the container body. And a cap with a bottom lid wound around the lower end of the body portion and a resin sealing liner attached to the inner surface of the top plate portion is placed over the container mouth portion. In a threaded can container in which a cap groove is formed around the cap skirt so as to form a screw groove in accordance with the screw thread, and the cap is wrapped and sealed, the screw thread overlaps the joint. The cap is formed in a direction in which the cap is opened from the upper side to the lower side of the combined stepped portions.

  Further, the invention of claim 2 is characterized in that in the invention of claim 1, at least the inner surface side joint portion of the container body portion is covered with a repair layer to which a thermoplastic resin film is attached. It is a can container.

  And invention of Claim 3 is invention of Claim 2, The part which coat | covers the said junction part among the said thermoplastic resin films is comprised with the tape-shaped resin film, The said in the circumferential direction of the said trunk | drum The width of the tape-shaped resin film is set to 7 mm to 15 mm, the thickness of the tape-shaped resin film is set to 15 μm to 45 μm, and the tape-shaped resin film is the first facing the joint portion. And a second layer that is superimposed on the first layer and is in contact with the contents on the inner surface side of the body portion, and the first layer has a melting point of 175 ° C. to 230 ° C., The second layer has a melting point of 200 ° C. to 255 ° C. and is made of a biaxially oriented resin, and the melting point of the resin constituting the second layer is the melting point of the resin constituting the first layer. A can container with a screw, characterized in that the thickness of the first layer is set to be more than 70% of the total thickness of the tape-like resin film. is there.

  The invention according to claim 4 is the invention according to claim 3, wherein the step of the joint portion is 0.07 mm or less and the diameter is reduced by 15% or more with respect to the can body diameter, and the top surface portion of the container mouth portion. The screw-shaped can container is characterized in that a step of the joint portion located at is set to 0.05 mm or less.

  According to the first aspect of the present invention, the screw thread is formed on the cylindrical container body portion having the overlapped joint portion formed with the step portion on the side surface, and the upper portion of the stepped portion overlapped with the joint portion. It is formed in the direction in which the cap is opened facing downward. In other words, with respect to the stepped portion that protrudes outward in the overlapping portion of the container body portion, the stepped mark that protrudes inward formed on the cap is the front in the circumferential direction that rotates the cap to open the cap. The thread is formed so as to be located on the side. Accordingly, when opening the cap, the step mark formed in the screw groove of the cap is not caught by the step portion of the joining portion (overlapping portion), the cap can be turned, and the opening performance can be improved. There is an effect.

  In addition, when opening the plug, it is possible to obtain a can container with a screw that prevents the occurrence of resin residue due to the edge portion of the stepped portion and prevents foreign matter from adhering to the drinking mouth.

  Furthermore, according to the invention according to claim 2, in addition to the effect of claim 1, even if severe molding is performed on the container mouth part in order to reduce the step of the curled part that affects the openability, that is, Corrosion resistance in this respect without causing damage such as cracking, peeling or breaking in the thermoplastic resin film that repairs the inner surface of the joint even when severe molding is performed on the threaded part or curled part. Can be improved.

  And according to the invention which concerns on Claim 3 and 4, the inner surface of the at least joined part of the said container trunk | drum is coat | covered by sticking a thermoplastic resin film, and a joined part is attached among the said thermoplastic resin films. The portion to be covered is made of a tape-shaped resin film, the width of the tape-shaped resin film in the circumferential direction of the body portion is set to 7 mm to 15 mm, and the thickness of the tape-shaped resin film is 15 μm to 45 μm. The tape-shaped resin film has a first layer facing the joint portion, and a second layer superimposed on the first layer and in contact with the contents on the inner surface side of the body portion. The first layer has a melting point of 175 ° C. to 230 ° C., and the second layer has a melting point of 200 ° C. to 255 ° C. and is made of a biaxially oriented resin. The melting point of the resin constituting the second layer is 15 ° C. to 80 ° C. higher than the melting point of the resin constituting the first layer, and the thickness of the first layer is the entire thickness of the tape-shaped resin film. By setting the thickness to more than 70% of the thickness, the first layer can be melted and completely covered up to the corner of the stepped portion of the joint portion, and the melting point of the first layer is higher than that of the first layer. Since the two layers do not melt, the biaxial orientation is maintained as it is, and the corrosion resistance on the inner surface side of the joint can be improved.

  In addition, when the cap is opened, the upper end of the container mouth is curled outward by forming a thread so that the cap is rotated in the direction from the upper side to the lower side of the stepped portion in the overlapping portion. In the curled portion of the outer winding, the inner side is turned over to become the outer side, so the step on the top surface of the curled portion is opposite to the step formed on the screw portion, and the curled portion of the container mouth portion The stepped part in the face will face the opening direction of the cap, but the stepped part is covered with a tape-shaped resin film, and the amount of the stepped part is made as small and smooth as possible to reduce the catch between the stepped part and the liner. Is possible.

  Accordingly, even when the container mouth is entrapped in the liner and the sealing performance of the container mouth and the cap is maintained well, the cap opening torque is reduced and the cap is smoothly opened.

  Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, the metal reseal can (can body excluding the cap) 1 of the present embodiment has a configuration in which a separate bottom lid 3 is wound and fixed to the lower end of the joint can body 2. That is, the container mouth 5 is formed above the cylindrical body 4, and the bottom lid 3 is wound and fixed to the opening end of the lower end of the can body 2. A metal pilfer loop cap 7 having a resin liner 6 is roll-on molded by a conventionally known capping device, and a screw groove 9 is formed in a cylindrical portion of the skirt portion 8 of the cap 7 and mounted. Is done.

  Further, as shown in FIG. 3, an annular bead portion (a groove on the inner surface and a ridge on the outer surface) 11 is formed in the container mouth portion 5 below the thread 10. Has been. When the metal cap 7 is attached to the container mouth 5 by a conventionally known capping device, the annular bead portion 11 is inserted into a forming roll (not shown) of the capping device, and the lower end wall (cap) of the cap 7 is inserted. The cap 7 is in a pilfer-proof state with respect to the container mouth portion 5 by pressing the upper step portion of the pill fur proof band 12 formed on the lower end of the skirt portion 8 of the skirt portion 7 against the upper step portion of the bead portion 11. It is to be locked with.

  The cap 7 of this embodiment is composed of a metal shell 13 and a resin sealing liner 6, and the shell 13 has a configuration in which the skirt portion 8 is suspended in a substantially cylindrical shape from the periphery of the top plate portion 14. The liner 6 is attached to the inner surface side (lower surface side) of the top plate portion 14. The lower end of the skirt portion 8 of the cap 7 (that is, the shell 13) in a state before being mounted on the container mouth portion 5 of the joint can body 2 by roll-on molding, that is, the skirt below the cylindrical portion where the screw is to be formed. The pilfer proof band 12 is formed in the part so that the bridge 12B formed between the horizontal slits 12A can be broken and separated.

  The material of the cap 7 (or shell 13) is not particularly limited. For example, a metal material such as an aluminum alloy plate coated with an epoxy-phenol resin in which an olefin resin powder is dispersed on the inner surface side is used. Used. The liner 6 is made of, for example, a conventionally known resin material such as a low-density polyethylene / ethylene-propylene copolymer synthetic rubber blend material, a polypropylene / styrene elastomer blend material, or a polyester elastomer. It is done. And the liner 6 is shape | molded by the well-known embossing method etc. which extrude and extrude the said resin material to the inner surface side of the top-plate part 14 in a molten state.

  On the other hand, the can body of the present embodiment is formed by forming a screw thread (male screw) 10 and a bead portion 11 at a neck portion obtained by reducing the diameter of the opening end of the cylindrical joining can body 2. It has been found from the applicant's various experiments that the direction of the step portion 15 on the side surface has a considerable influence on the opening performance.

  Here, the joining can body 2 and the stepped portion 15 will be described. The joining can body 2 cuts the above-described metal material into a size corresponding to one can and forms it into a cylindrical shape, and both ends of the metal material. The parts are slightly overlapped and welded. The joint portion 16 formed in this way is shown as an enlarged cross-sectional view in FIG. 4, and the joint portion 16 is thicker than the other portions, so that a step portion 15 is generated. And the level | step difference part 15 differs in the direction which becomes convex in the outer surface side and inner surface side of the joining can body 2, and in the example shown in FIG. 4, the left side part of FIG. Contrary to this, on the inner surface side, the right side is a step that protrudes inward.

  That is, when roll-on molding is performed by putting the cap 7 on the container mouth portion 5, the shell 13 placed on the container mouth portion 5 is pressed against the thread 10 of the neck portion by the screw forming roll, so that the joint can body 2 is drawn. The step portion 15 of the neck portion thus formed is transferred to the cap 7, and as a result, a step mark 17 due to the step portion 15 of the joining can barrel 2 is formed in the screw groove 9 of the cap 7. Then, the step mark 17 formed in the screw groove 9 of the cap 7 faces the step part 15 in the joint part 16 on the can body 2 side, and the cap 7 is attached to the container mouth part 5. More specifically, the inclined surface of the step mark 17 on the inner surface side of the cap 7 and the inclined surface of the step portion 15 on the outer surface side of the joint portion 16 face each other, or the inner surface of the screw groove 9 of the cap 7. The step mark 17 on the side and the step part 15 on the outer surface side of the container mouth part 5 or the neck part are engaged with each other.

  When the cap 7 is opened by turning the cap 7 in a direction in which the step marks 17 and the step portions 15 are more positively or strongly engaged, the step marks 17 of the cap 7 cause the step portions 15 of the neck portion of the joint portion 16 to It has been found that if it is not overcome, it is impossible to open the cap, and this causes the opening torque of the cap 7 to start to increase.

  Further, when the cap 7 is opened, when the stepped portion 15 of the joint portion 16 is climbed, the coating on the edge of the stepped portion 15 is peeled off, or the inner surface coating film of the cap 7 is scraped by the edge, so There is a possibility of adhering to the container mouth part 5, and the sealing performance at the time of re-sealing may be deteriorated or may be mixed into the contents, which is not preferable in terms of hygiene.

  As a countermeasure, the joining can barrel 2 of the present embodiment has a state in which the step mark 17 of the screw groove 9 in the cap 7 faces the step portion 15 of the joining portion 16 in the neck portion of the can barrel 2. Even when the container mouth 5 is attached, when opening the cap, the cap 7 is opened by turning the cap 7 in the direction in which the step mark 17 of the cap 7 and the step 15 of the joint 16 are separated from each other. ing. That is, the thread 10 formed in the neck portion is from the upper side (the outer surface side of the can body 1 or the outer side in the radial direction of the can body 1) to the lower side (the inner surface side of the can body 1). Alternatively, the cap 7 is formed in the direction in which the cap 7 is opened toward the inside in the radial direction of the can body 1. Therefore, when the cap 7 is opened, the inner surface of the screw groove 9 (female screw) of the cap 7 can be rotated without being caught by the step of the joint portion 16.

  When the cap 7 is once opened, the cap's pilfer proof band is cut off and the skirt is widened, and when it is to be sealed again, the gap between the screw thread 10 and the screw groove 9 or the step 15 As shown in FIG. 5, the gap C between the step mark 17 and the step mark 17 becomes larger than before opening. Therefore, the step portion 15 and the step mark 17 no longer cause a problem at the time of resealing (at the time of resealing).

  On the other hand, in the curled portion 18 formed at the end portion of the joining can body 2, when the curled portion 18 is wound around the outer winding, the joining portion 16 is turned upside down on the top surface of the curled portion 18. Therefore, the direction of the stepped portion 15 on the top surface of the curled portion 18 appears opposite to the direction of the stepped portion 15 of the neck portion. For this reason, it is necessary to reduce the amount of the step than the step portion 15 formed on the screw thread 10 so that the step portion 15 on the top surface does not affect the beginning of the rotation of the cap 7 when opening. It is preferable that welding is performed so that the level difference when joining the can body 2 is as small as possible from the stage of joining the cylinder, and preferably 0.07 mm or less. Further, the diameter of the mouth portion 5 of the can body 2 thus welded is reduced by 15% or more with respect to the diameter of the can body 2, and the step amount of the step portion 15 of the neck portion is reduced by the compressive force from the circumferential direction. It is preferable to do so.

  In the die neck molding method in which the diameter reduction ratio of the container mouth portion 5 with respect to the can body diameter is smaller than 15%, the degree of plastic working of the joint portion 16 is small, and it is not expected to reduce the step amount of the joint portion 16.

  As shown in FIG. 6 (A), there is a case where a cap having a panel with the top plate 14 greatly recessed is used in addition to the shape of the top plate having a substantially flat shape. When a simple cap is attached to the container mouth, the diameter reduction ratio of the container mouth acts effectively.

  In other words, when the curled portion 18 is formed by folding and precurling the opening end portion of the container mouth portion 5 and crushing from the side, the cap top plate portion 14 is formed because the curled portion 18 is formed in an elongated shape. The contact load between the curled portion 18 and the liner 6 due to the compressive load that presses is smaller than that of a round cross-section (or irregular cross-section) curl, and the sealing performance tends to be lowered. Therefore, in order to compensate for the contact load, as shown in FIG. 6 (B), the cap 7 is pressed by using a re-forming tool (not shown) while pressing the top plate portion 14 of the cap shell 13 at the time of roll-on molding. The corner portion 14a of the panel is deformed outward, the corner portion 7a of the cap 7 is deformed inward, and the curled portion 18 is sandwiched from both sides via the liner 6 to increase the adhesion of the liner 6. Is done. Even in such a case, if the diameter reduction processing is performed on the container mouth portion 5 at the above-mentioned diameter reduction ratio, the level difference of the joint portion on the surface of the curled portion 18 in contact with the liner 6 can be reduced to 0.05 mm or less. The influence on the plug property can be reduced.

  The bonding can body 2 is mainly of both bonding and welding types, but particularly in the case of a welding can by a welding method, the covering layer 19 formed on the steel plate produces the bonding can body 2 as shown in FIG. A region to be joined at both ends to be joined at times is formed leaving a width of about 1.5 mm to 3.0 mm. Since welding is performed in an unpainted state, a repair coating in this region is necessary from the viewpoint of corrosion resistance after welding. The cylindrical body 4 is manufactured in a state in which the step portion 15 is formed at least in the joint portion 16. In this way, the bonded can body 2 is manufactured in which the coating layer 19 is applied to the inner peripheral surface excluding the cylindrical body portion 4 and the joint portion 16 of the body portion 4.

  The joint portion 16 in an unrepaired state on the inner surface side of the joint can body 2 is covered with an inner surface repair resin. In FIG. 7, the width of the inner surface repair coating layer 20 in the circumferential direction of the body portion 4 is set within a range of 7 mm to 15 mm from the viewpoint of coverage and workability. The inner surface repair coating layer 20 can be formed as a single layer or a composite layer. As a method of forming the inner surface repair coating layer 20, there are a method of applying an inner surface coating and a method of applying a tape-like resin film. is there.

  Curing type synthetic resin such as polyester or phenolic type, especially thermosetting type synthetic resin is used as the coating material for repair coating, but after the coating film is baked, the hardness is increased and necking of the opening end, curl molding and Thick coating cannot be performed because there is a risk of coating film cracking or film peeling during crushing molding in which the curled portion is folded and crushed. For this reason, in consideration of corrosion resistance, a method of attaching a tape-shaped resin film is desirable.

  In the case of corresponding to molding with a repair paint, it is conceivable to repair thinly, but if the thickness of the inner surface repair coating layer 20 is thin, it is difficult to completely repair the welding step 15 due to fluidity, In order to improve the openability, when severe post-processing such as neck molding or curl molding is severe, there is a possibility that the coating film is damaged and the corrosion resistance becomes insufficient. On the other hand, by sticking a tape-shaped resin film having a certain thickness, it is possible to suppress adverse effects on corrosion resistance and the like. In particular, when curling the neck opening end, from the viewpoint of ensuring sealing performance and smoothness of the top surface of the curled portion, after curling and curling, the curled portion is pressed from the side surface and crushed into a laminated state Even in harsh molding where the film is formed, the film is not damaged or peeled off, and the corrosion resistance can be maintained.

  When repairing by attaching a tape-shaped resin film, the temperature of the area where the tape-shaped resin film is applied on the inner surface of the body portion 4 is heated within a range of 170 ° C. to 230 ° C., and then the tape-shaped resin is applied to the area. Crimp the film. As a method for attaching the tape-shaped resin film, the tape-shaped resin film itself may be heat-adhesive, or a thermosetting resin adhesive layer may be provided on the tape-shaped resin film. Examples of the tape-like resin film include polyester resins such as polyethylene terephthalate resin and polybutylene terephthalate resin, copolymer polyester resins made of copolymerization of polyethylene terephthalate and isophthalate, polypropylene resin, polycarbonate resin, polystyrene, and the like. A transparent thermoplastic polymer resin selected from a resin, a polyolefin resin, a vinyl chloride resin, or the like, or a tape-shaped resin film made of a composite of the above resins is used. The thickness of the tape-like resin film attached to the inner surface side of the body part 4 is preferably set in the range of 15 μm to 45 μm from the viewpoints of coverage, workability, and post-workability.

  The tape-shaped resin film may be unstretched or stretched, but is preferably formed of a composite layer. In this case, the tape-shaped resin film is superimposed on the first layer facing the body 4 side and the first layer. And a second layer facing the inner side of the body portion 4. The first layer is made of a thermoplastic resin having a melting point in the range of 175 ° C. to 230 ° C., and the second layer has a melting point in the range of 200 ° C. to 255 ° C. and is biaxially oriented. It is preferably composed of a thermoplastic resin.

  Further, the first melting point of the thermoplastic resin constituting the second layer is 15 ° C. to 80 ° C., more preferably 20 ° C. to 40 ° C. higher than the melting point of the thermoplastic resin constituting the first layer. Layer and second layer materials are selected. Furthermore, the thickness of the first layer is set to a thickness exceeding 70% with respect to the entire thickness of the tape-shaped resin film. In addition, after this tape-shaped resin film is pressure-bonded to the joint portion 16, post-heating is performed at a temperature higher than the melting point of the first layer and lower than the melting point of the second layer. As the thermoplastic resin used here, for example, a polyethylene resin, a modified polyethylene resin, a polypropylene resin, a modified polypropylene resin, and a polyolefin resin can be used, but the inner surface coating layer 19 is a polyester resin such as a polyethylene terephthalate resin. In the case of using polyester, it is preferable to use a polyester resin as the first layer from the viewpoint of adhesion between the resins. Furthermore, the thickness of the inner surface repair coating layer 20 is set in the range of 15 ° C. to 45 μm, more preferably in the range of 18 μm to 30 μm, in consideration of corrosion resistance, workability and post-workability.

  Further, by setting the thickness of the first layer to 70% or more of the total thickness of the tape-shaped resin film, it is possible to completely cover the corners of the stepped portion 15 on the inner surface side of the joint portion 16, and to prevent rusting. Occurrence can be reliably prevented. Moreover, it is preferable to coat | cover the junction part 16 of an inner surface side with the tape-shaped repair film of thickness 15 micrometers or more. As a result, the level difference on the surface of the curled part can be further reduced, and the level difference of 0.05 mm or less, preferably 0.04 mm or less, with the level difference part 15 of the joint 16 on the surface of the curl part covered with the tape-like resin film. Therefore, the hooking resistance with the liner 6 can be reduced when the cap is opened.

  If the thickness of the tape-like resin film covering the inner surface side of the joint portion 16 is smaller than 15 μm, handling during transport in the process of being attached to the joint portion 16 on the inner surface of the can body 2 becomes difficult, and the thickness is larger than 45 μm. Then, the handling problem at the time of conveyance disappears, but it becomes difficult to cut the film easily, and the film is coated to a thickness more than necessary, which is not very economical.

  The material of the can body 2 of the present embodiment is a commonly used can body material for a three-piece can. For example, tin-free steel having a two-layer coating of metal chromium and hydrated chromium oxide, tin plating, Examples include tin-plated steel sheets subjected to chromate treatment, ultra-thin tin-plated steel sheets subjected to thin tin plating and chromate treatment after nickel plating and diffusion treatment, nickel-plated steel sheets subjected to nickel plating and chromate treatment, and the like. A steel sheet in which a coating layer (this becomes an inner surface coating layer 19 to be described later) is formed on one surface of the surface-treated steel sheet for can making (the surface constituting the inner surface of the can body), and the plate thickness is 0.10-0. .25 mm is used.

Specifically, the adhesion amount 0.5 to 3.0 g / ^{m 2} after tin plating, tin-plated steel sheet subjected to chemical conversion treatment, after nickel plating of Ni deposition amount 0.3 to 2.0 g / ^{m 2,} the chemical conversion after the nickel plated steel plate subjected to treatment, each 0.5 to 2.0 g ^/ m 2 as Sn and Ni deposition amount, the 0.1 to 0.5 g / ^{m 2} was plated Ni, in the order of Sn, facilities and chemical processing Sn / Ni-plated steel plate, chromium-chromate treated steel plate usually called tin-free steel having a metal chromium adhesion amount of 50 to 120 mg / m ² and a chromium oxide adhesion amount of 5 to 20 mg / m ² .

  The outer surface of the junction can body 2 of the present embodiment is decorated with characters, symbols, and the like. As a method for this purpose, a dry laminating method in which a film on which a lubricant film has been applied and a pattern printed in advance is laminated on a steel sheet coated with an adhesive, or a lubricant film and a pattern on a synthetic resin film such as polyethylene terephthalate in advance. After printing, applying a thermosetting or thermoplastic adhesive to the ink layer surface, laminating the dried film on the heated steel plate, the other side of the film with pattern printing and lubrication film on one side The resin-coated steel sheet obtained in this way can be produced by a conventional means for making a three-piece can such as a welded can or an adhesive can.

  Next, the inner and outer surface coating film applied to the present embodiment is a polyester-based resin film, and a film having a high melting point of about 260 ° C. is obtained by selecting an alcohol component and an acid component. Since the heat resistance in the can manufacturing process and the filling process can be secured by imparting the properties, the applicability is wide and preferable.

  As the inner surface coating film 19, a thermoplastic resin film having a thickness of 20 μm or less is applied. However, if the thickness is less than 5 μm, the film is damaged in the can-making process, which causes rusting, which is not preferable. . Moreover, in order to ensure rust resistance, it is advantageous that the film is thick, but if it is too thick, the economy is poor. Therefore, the thickness of the laminated inner surface coating film 19 is preferably in the range of 5 to 20 μm.

  On the other hand, the outer surface coating film 21 is often printed to display canned contents, brands, etc., and a thermoplastic resin film having a thickness of 20 μm or less is applied. If the film thickness is less than 8 μm, printing is performed. It is not preferable because transportability in the process becomes difficult, and if it is thicker than 20 μm, the appearance may be deteriorated, and it is not economical. Therefore, the thickness of the laminated outer surface coating film 21 is preferably in the range of 8 to 20 μm. In addition, as the printing ink, an ink having excellent heat resistance and retort resistance using a urethane resin as a main binder is used, and the thickness of the printing ink layer varies depending on the printing pattern.

  As the printing method, conventionally known various printing methods are appropriately used, and gravure printing is preferable from the viewpoint of upgrading the printing appearance.

  Moreover, you may use an adhesive agent for the coating film laminated | stacked, In that case, the thickness of an adhesive agent is set in the range of 1 micrometer-10 micrometers. In particular, in order to improve the design on the appearance of the can in the product state, it is preferable to set the thickness of the adhesive within a range of 5 μm to 7 μm. In addition, a white pigment such as titanium oxide may be added to the adhesive for the purpose of hiding the metal color of the steel sheet.

  In addition, the thermosetting organic coating layer (base coat layer) that may be used as the base of the coated resin film is a pre-printed film that is laminated with sufficient adhesion on the entire surface of the can size, This is to ensure sufficient adhesive strength that does not peel off during processing or heat sterilization after filling the contents. This thermosetting organic coating film layer may be added with a white pigment such as titanium oxide in order to further ensure the sharpness of printing. The pigment added in the thermosetting organic coating layer is selected in the range of 1 to 30% by weight. When adding a white pigment, if less than 1%, the effect of whitening is small, and if it exceeds 30%, the effect of whitening is almost saturated and the properties of the coating film tend to deteriorate, preferably 30% or less. A more desirable range is from 10 to 25%. The thickness of the coating layer that does not include the white face department may be 1 to 3 μm, and the thickness of the coating layer that includes the white pigment is 5 to 15 μm.

A thread 10 is formed in the neck portion of the joint can body 2 in a direction in which the cap 7 is opened from the upper side to the lower side of the joint part 16 (overlapping part). Therefore, when the cap 7 is opened, the inner surface of the screw groove (female screw) 9 of the cap 7 can be turned without being caught by the stepped portion of the joint portion 16. On the other hand, the stepped portion on the surface of the curled portion 18 formed at the end of the joint can body 2 has a smaller step amount than the stepped portion formed on the screw thread 10. This can be achieved by reducing the diameter of the end of the joint can body 2 and covering the inner joint 16 with a tape-like resin film. The effect of reducing the hooking resistance and reducing the opening torque is promoted.
<In case of film sticking can>

  For external printing, from a variety of small lots, from steel plates or plain steel plates coated with a transparent or plain color thermoplastic resin film or a white thermoplastic resin film (sometimes with titanium white in the adhesive layer) It is also possible to affix a printed thermoplastic resin film for one can cut to a length equal to or longer than the entire circumference of the can body to the joining can body 2 formed in a cylindrical shape as an outer surface covering film. By doing so, the printed design can be applied to the outer surface side also serving as a repair coating for the outer surface side or the joint portion 16 on the outer surface side.

  Examples of the thermoplastic resin film for pasting include, for example, homopolyester resins such as polyethylene terephthalate resin and polybutylene terephthalate resin, copolymer polyester resins made of copolymerization of polyethylene terephthalate and isophthalate acid, polypropylene, and the like. A transparent polymer resin alone selected from a resin, a polycarbonate resin, a polystyrene resin, a polyolefin resin, a vinyl chloride resin, or a thermoplastic resin film made of a mixture or composite of the above resins is used. And, it has a clear coat layer formed on one side of the thermoplastic resin film, and the surface opposite to the clear coat layer is printed. As this printing, gravure printing method, flexographic printing Method, inkjet printing method, screen printing method, electrophotographic printing method and the like can be used. In terms of design, it is preferable to use gravure printing with a clear image quality and a high-class feeling.

  The adhesive used for the above-mentioned thermoplastic resin film for pasting does not cause film peeling by baking, threading, or curling of a repair coating layer, which will be described later. It is necessary to select one that does not cause peeling, and a thermosetting adhesive such as polyester, polyurethane, epoxy, or polyethylene is used.

  The polyurethane-based adhesive is a polyisocyanate used alone or mixed with a compound such as a polyol containing active hydrogen that easily reacts with an isocyanate group. Specific examples of the polyisocyanate compound include ethylene diisocyanate, 1,6. -Aliphatic diisocyanates such as hexamethylene isocyanate, alicyclic diisocyanates such as isophorone diisocyanate, and aromatic diisocyanates such as naphthalene diisocyanate. Examples of the polyol compound include polyester polyol and polycarbonate polyol.

  Furthermore, examples of the epoxy adhesive include bisphenol A or diglycidyl ether of phenol resin and oligomers thereof, orthophthalic acid diglycidyl ester, isophthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, and the like. Furthermore, the adhesive used in the present embodiment includes, for example, white pigments such as titanium dioxide and zinc white, yellow pigments such as zinc yellow, red pigments such as vermilion and bengara, bitumen, cobalt blue and the like according to applications and purposes. Blue pigments, green pigments such as chrome green and green earth can be blended.

  The outermost clear coat layer is provided from the viewpoint of preventing scratching of the film in the high-speed can-making process and improving the slipperiness on the outer surface side of the thermoplastic resin film, and has a coefficient of static friction of 0.2 or less. For example, an acrylic or polyester-based paint to which Si-based fine particles or an organic lubricant is added is applied. The thickness is 0.5-4 μm. If it is less than 0.5 μm, the friction coefficient is not reduced and no effect is seen. If it exceeds 4 μm, there is no further decrease in the friction coefficient, and the effect becomes saturated. The clear coat layer is for improving the slipperiness on the outer surface side of the thermoplastic resin film and preventing scratches. As the clear coat layer, for example, a polyester resin, an epoxy resin, an epoxy-modified polyester resin, an acrylic resin, or the like added with a curing agent such as an amino resin is used. In addition, you may make a hardening | curing agent contain a well-known lubricant.

Moreover, in the outer surface printing film to be attached as a film attachment can, the length in the circumferential direction is set to be about 0.5 mm to 5 mm longer than the entire circumference of the can body 2, and the length of the outer surface printing film is a can. The length is set to be shorter by 0.3 mm to 1 mm so as not to protrude beyond the height of the body 2. In addition, it is preferable from the point of rust prevention to repair the exposed metal parts that are not covered with film. For example, felt that includes paint in the vicinity of both ends of a cylindrical container body to which an outer printed film is attached. It is preferable to press and cover the material.
(Example)

  The outer surface coating film is a 12 μm biaxially stretched polyester film, coated with 2 μm of thermosetting polyester paint with silicone lubricant added, dried, and then gravure printed (2 μm) on the opposite side with 4 color trademark designs. On the ink layer, a 5 μm urethane adhesive added with titanium oxide was applied and dried. The total thickness of the manufactured printed film was 21 μm.

  The total thickness of the 11 μm biaxially stretched polyester film and the urethane adhesive 1 μm film was 12 μm.

  On the other hand, the above-mentioned printed film and inner surface coating film were each thermocompression bonded to a steel plate having a plate thickness of 0.19 mm and a hardness of T2.5, which was subjected to a normal chromium / chromate treatment.

  From the laminated steel sheet thus obtained, a bonded can body is produced by forming a cylindrical shape so that the surface of the printed film becomes the outer surface of the can, and overlapping and welding the ends thereof (of the joined portion of the can body) Step 0.06 mm), the joint 16 is repair-painted on the outer surface side of the joint can body with an epoxy resin thermosetting paint 22 (see FIG. 7), and the inner surface side of the joint 16 is a tape-like polyester resin film 20 Repair coating.

  Therefore, the first layer of the inner surface coating of the joint can body is made of a thermoplastic resin having a melting point of 205 ° C., and the second layer is made of a biaxially oriented thermoplastic resin having a melting point of 235 ° C. Furthermore, the melting point of the thermoplastic resin constituting the second layer is 30 ° C. higher than the melting point of the thermoplastic resin constituting the first layer. Furthermore, the thickness of the first layer is 82% of the total thickness of the tape-shaped resin film.

  The 200-diameter jointed can body produced in this way (can body inner diameter φ50) was expanded to 202 diameter, and the neck of the open end of the unexpanded portion was subjected to neck-in multiple times, and the neck with a diameter reduction ratio of 20%. An inner diameter φ40 is formed, and the opening end is folded and precurled and threaded to form a screw thread 10. Then, a seam curl (precurled portion crushing) is formed and a step difference on the surface of the curled portion is set to 0. 04 mm or less. And bead molding was performed. Next, an aluminum cap (an epoxy-phenol resin in which an olefin resin powder is dispersed is applied on the inner surface side is applied to the container mouth portion in which the screw thread is formed, and the low-density polyethylene and ethylene-propylene copolymer are coated on the liner. Using a well-known synthetic capping device and applying pressure to the top plate of the cap using a well-known synthetic capping device, each forming roll (not shown) of the threading roll and the stationary roll Is pressed against the peripheral surface of the cap to deform the cylindrical part of the cap skirt so that it follows the thread (male thread) of the container mouth. The lower end of the pill fur proof band formed in the cap is wrapped around the bead portion of the container mouth portion so as to engage with the upper portion of the container mouth portion. Mounted, the stepped portion of the joint to produce a threaded can container of the wide-mouth directed in the unplugging direction.

  An appropriate amount of warm water of 80 ° C. was filled in this threaded can container, and then a bottom cover was wrapped and sealed at the other open end of the can body, and pressure sterilization was performed in a retort kettle at 125 ° C. for 30 minutes. After that, when the opening torque was measured, a can container with a screw in which the step portion of the joint portion was directed in the direction opposite to the opening direction (the step portion in the screw groove and the step mark transferred to the cap opened the cap). The opening torque was reduced by about 10% in comparison with can containers in which screws were formed so as to mesh with each other by turning in the stopper direction.

  In addition, after opening the bottle, the outer surface of the can body and the inner surface of the cap, especially the joint of the can body or the vicinity thereof were checked for the presence or absence of foreign matter, but there was no adhesion of paint film and there was no quality problem. . In addition, although the opening direction of this embodiment is a right-hand thread, it is only necessary that the stepped portion of the joint is directed in the same direction as the opening direction, and the present invention can also be applied to a left-hand thread.

It is a front view which shows the wide mouth reseal can with a roll-on cap which is an example of this invention. It is a front view which shows the cap before roll-on shaping | molding, and the joining can body which has not tightened the bottom cover. It is a fragmentary sectional view which mainly shows the curl part and liner of a container mouth part. It is a typical figure which shows the opening part of the junction part of a container trunk | drum and a cap, Comprising: It is the elements on larger scale which show the fitting state of the cap at the time of opening. It is a schematic diagram which shows the opening part of the junction part of a container trunk | drum and a cap, Comprising: It is a fragmentary sectional view which shows the fitting state of the junction part in the middle of the operation which reseals after opening, and a cap. They are the partial expanded sectional view (A) which shows the fitting state of the curl part of a container mouth part before roll-on shaping | molding, and a liner, and the partial enlarged sectional view (B) which shows the state after roll-on shaping | molding. It is a fragmentary sectional view which shows the junction part by welding.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Reseal can (can body), 2 ... Joining can body, 3 ... Bottom cover, 5 ... Container mouth part, 7 ... Cap, 9 ... Screw groove, 10 ... Screw thread, 13 ... Shell, 16 ... Joining part, 17 ... Step mark, 18 ... Curl part, 19 ... Coating layer, 20 ... Inner surface repair coating layer, 21 ... Outer surface coating film, 22 ... Thermosetting paint (outer surface repair coating layer).

Claims (4)

There is a cylindrical container body having an overlapped joint with a step formed on the side surface, and a container mouth formed with a thread and a curl at the open end of the container body. Cover the container mouth with a cap with a bottom lid wrapped around the lower end and a resin sealing liner attached to the inner surface of the top plate, and thread the groove on the skirt of the cap according to the thread. In a can container with a screw sealed with a cap wrapped around the container mouth as if formed,
The threaded can container, wherein the screw thread is formed in a direction in which the cap is opened from the upper side to the lower side of the overlapped stepped portion with respect to the joint portion.   2. The threaded can container according to claim 1, wherein at least an inner surface side joint portion of the container body portion is covered with a repair layer to which a thermoplastic resin film is attached. Of the thermoplastic resin film, the portion covering the joint portion is constituted by a tape-shaped resin film, the width of the tape-shaped resin film in the circumferential direction of the body portion is set to 7 mm to 15 mm, and While the thickness of the tape-shaped resin film is set to 15 μm to 45 μm,
The tape-shaped resin film has a first layer facing the joint portion, and a second layer superimposed on the first layer and in contact with the contents on the inner surface side of the body portion, The first layer has a melting point of 175 ° C. to 230 ° C., the second layer has a melting point of 200 ° C. to 255 ° C., and is composed of a biaxially oriented resin to constitute the second layer. The melting point of the resin is 15 ° C. to 80 ° C. higher than the melting point of the resin constituting the first layer, and the thickness of the first layer exceeds 70% of the total thickness of the tape-shaped resin film. The threaded can container according to claim 2, wherein   The step of the joint is 0.07 mm or less, and the diameter is reduced by 15% or more with respect to the can body diameter, and the step of the joint located at the top surface of the container mouth is set to 0.05 mm or less. The can container with a screw according to claim 3 characterized by things.

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