JP2002292785A - Method for manufacturing printed film bonded can body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a printed film bonded can body, not bringing about the deterioration of content-resistant properties or production efficiency caused by the softening of a protective film at the time of bonding of a printed resin film and preventing the peeling of the printed resin film or the protective film from the can body at the time of subsequent processing of the can body. SOLUTION: As the protective film 12 on the inner surface side of the can, a film comprising a thermoplastic resin with a stickiness starting temperature of 170 deg.C or higher is used and, as the adhesive layer 24 of the printed resin film 20, a layer comprising a resin thermally bondable to the thermoplastic resin of the protective film 13 on the outer surface side of the can is used. When the printed resin film 20 is bonded to the outer surface of the body part of the can body 1A integrally molded from a coated metal panel 10 of which both inner and outer surfaces are coated with the protective films 12 and 13, the can body is subjected to short-time post heat treatment at a temperature, which is not lower than the activation temperature of the adhesive layer 24 of the printed resin film 20 and not lower than the melting points of the thermoplastic resins of the protective films 12 and 13 covering both inner and outer surfaces of the can body 1A, and immediately subjected to quenching treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a printed film-laminated can body having a printed resin film adhered to the outer surface of the body of the can body, and more particularly to a method for producing an amorphous amorphous body. For a can body that is integrally molded from a coated metal plate whose inner and outer surfaces are coated with a protective coating of a thermoplastic resin, a resin film printed on the outer surface of the body of the heated can body is bonded to an adhesive layer. The present invention relates to a method for producing a printed film-adhered can body, which is further processed after being adhered through a can.

[0002]

2. Description of the Related Art An appropriate printing method such as gravure printing or overprinting by offset printing can be applied to a three-piece can in which characters and / or patterns are previously printed on a blank for a plate-shaped can body. On the other hand, in the case of a two-piece can in which the body and the bottom are integrally formed, printing is performed on the body of a can body (a two-piece can body) formed in a cylindrical shape with a bottom. Conventionally, dry offset printing is generally applied because overprinting by printing or offset printing is practically impossible, but in this printing method,
Overprinting with inks of different colors is virtually impossible, and the number of colors and color tones are limited, so realistic printing that faithfully reproduces the appearance of the actual food and other materials filled in the can, even with subtle color changes. It is impossible to perform luxurious and elegant decorative printing using multicolor inks.

However, with regard to canned products made of two-piece cans, a more beautiful appearance is required due to diversification of products due to changes in consumption trends and needs, and for this reason, for example, Japanese Patent Application Laid-Open No. 9-29539 and Kaiping 1
As described in 1-1147515 and the like,
Rather than directly printing on the outer surface of the body of the can, beautiful multicolor printing characters and patterns are applied to a thermoplastic resin film such as a biaxially oriented polyester resin film by a gravure printing method in advance. At the same time, an adhesive layer of a thermosetting resin is formed on the inner surface side of the printed resin film (the surface in contact with the outer surface of the body of the can), and the printed resin film is coated with the adhesive layer. Conventionally, it is possible to provide a print design of characters and designs by gravure printing or the like to the outer surface of the body of a two-piece can by attaching it to the outer surface of the body of the can via a heat bonding method. And commercial production has actually been done.

On the other hand, bisphenol A, which is a raw material of thermosetting epoxy resin and phenolic resin, which has been widely used as a paint applied as a protective coating on a metal surface of a can body, has recently entered the human body. Since the theory that it acts like a hormone and adversely affects fertility has been published and has become a problem, protection of thermoplastic resins such as polyester resins, polypropylene resins, polyethylene resins, and polyamide resins that do not contain bisphenol A is protected. The coating is laminated on one surface (metal surface on the inner surface of the can) or both surfaces of the metal plate, and from the coated metal plate, a two-piece can body (body and bottom) or a three-piece can body (glasses can) ) And can lids (canopies and bottom lids) have been proposed,
2. Description of the Related Art Two-piece can bodies (can bodies) are manufactured from electrolytic chromic acid-treated steel sheets having a polyester resin film (film) laminated on both sides.

[0005] However, after a protective film of a thermoplastic resin such as a polyester resin or a polyolefin resin is coated on only one surface of the metal plate (the metal surface on the inner side of the can),
When a cup is formed by punching and drawing, then redrawing is performed to form a deep drawn can, or when redrawing is performed and then further ironed to form a drawn and drawn can, a metal plate is used. Other side (metal surface on the outer side of the can)
It is necessary to redraw or iron while applying or spraying a large amount of lubricant, otherwise,
When redrawing or ironing, heat is generated by forming a metal plate, so that the cup is burned to the redrawing die (die) or ironing die (die), or the body of the cup is damaged. There is a problem that the can is continuously broken due to breakage.

Therefore, when only the metal surface on the inner side of the can of the metal plate is coated with the protective coating of the thermoplastic resin and the opposite metal surface is not coated with the protective coating of the thermoplastic resin, both sides of the metal plate are required. A large amount of lubricant is used as compared with a case where the lubricant is coated with a protective coating of a thermoplastic resin, and a large amount of washing is required since a step of degreasing, chemical conversion, and washing with the lubricant is required. Water is needed, and
It is necessary to apply a new spray coating of thermosetting resin or the like as a protective coating on the bottom of the can body that will not be subjected to characters or patterns by direct printing or pasting of a printed resin film later. (If the protective coating is not applied, the bottom metal surface may corrode during storage of the can body or canned product).

On the other hand, a can body (seamless metal can) is formed by drawing and ironing or deep drawing using a coated metal plate whose both surfaces are coated with a protective coating of a thermoplastic resin. For example, it is known that a printed resin film having a beautiful print design previously applied by gravure printing is attached to the outer surface side of the body of the can body thus formed by thermal bonding, for example, as described in JP-A-2000-2000. -17
It has been conventionally known, for example, from JP-A-7745.

That is, a high-temperature volatile lubricant (glamor wax) is uniformly applied to a coated metal plate having both surfaces of an aluminum alloy plate coated with a thermoplastic copolyester resin film. At the same time as drawing and ironing, thinning is performed by drawing and ironing to form a deep drawing cup, then doming molding according to the usual method, and then heat-treating the deep drawing cup to remove processing distortion of the film and wax It is disclosed in the above-mentioned publication that a can body before the printed resin film is attached is manufactured by volatilizing and removing the resin.

[0009] By integrally molding the can body from the coated metal plate in which both surfaces of the metal plate are coated with the protective coating of the thermoplastic resin, the amount of the lubricant used during the molding process can be reduced, and the lubrication after the molding is performed. There is no need to use a large amount of washing water to remove the agent, and after forming into a cylindrical bottomed body (deep drawing cup), spray the protective coating on the inner surface and outer surface of the can. It is not necessary, and the protective coating on the inner surface of the can that comes into contact with the contents of the can is made of a copolymerized polyester resin that is a thermoplastic resin that does not contain bisphenol A. There is an advantage that there is no fear that bisphenol A elutes.

[0010] When the can body is integrally formed from the coated metal plate in which both surfaces of the metal plate are coated with the protective coating of the thermoplastic resin, the coated metal plate before the can body is integrally formed is as follows. It is preferable to make the thermoplastic resin of the protective coating covering both surfaces of the metal plate amorphous from the viewpoint of the adhesion between the protective coating and the metal plate and the moldability of the coated metal plate.

[0011]

By the way, as described above, a can body (seamless metal can) integrally formed from a coated metal plate coated on both sides with a protective coating of a thermoplastic resin is printed on the outer surface of the body. When attaching the resin film, the can body is heated in advance by high-frequency induction heating or the like so that the temperature is equal to or higher than the thermal bonding temperature of the adhesive layer formed on the printed resin film, and the film is attached. For the can body attached to the mandrel of the device, the printed resin film cut into sheets of the size of each can is placed so that the adhesive layer side contacts the outer surface of the body of the can body. It is heat-bonded by pressing with a sticking roll to stick it.

The can body to which the printed resin film is adhered is usually subjected to neck-in processing for reducing the diameter of the opening end by one or more steps, and further to flange processing. While there is a risk that the printed resin film may peel off from the metal surface of the can body during the processing of some of the can bodies, the printed resin film and the can can be separated to such an extent that such peeling does not occur. Conventionally, the temperature of the can (the temperature of the outer surface of the body of the can) before applying the printed resin film is preferably 170 to 210 ° C. so that the adhesion of the body can be sufficiently ensured. Heating.

However, as a result of the research by the present inventors, when the printed resin film is adhered while the can body is heated to a temperature of 170 to 210 ° C., the following problems may occur. found. That is, when attaching the printed resin film, the can body is heated to a relatively high temperature (170 to 210 ° C.), and the protective coating of the thermoplastic resin covering the inner surface side of the can becomes softened. The can body is strongly pressed by the mandrel of the film sticking device by the pressing force applied from the sticking roll to the can at the time of sticking the film, and the thermoplastic resin of the protective coating covering the inner side of the can turns white. Each time the film sticks, it becomes difficult to separate the can body from the mandrel because the mandrel of the film sticking device and the thermoplastic resin on the inner surface of the can stick and the can body is difficult to come off. It has been found that there is a problem that the production efficiency deteriorates due to the necessity of stopping the dressing device.

On the other hand, in order to solve such a problem, the inventor of the present invention has proposed a method for producing a printed film-adhered can body, wherein the protective coating on the inner surface of the can has an adhesion initiation temperature of 170 ° C. or higher. The thermoplastic resin of the above is used, and as the adhesive layer of the printed resin film, a resin that can be thermally bonded at 100 to 160 ° C. with the thermoplastic resin of the protective coating on the outer surface of the can is used. At the time of sticking to the outer surface of the torso, the temperature of the outer surface of the torso of the can is set to 100 to 160 ° C., and the can after the printed resin film is adhered is bonded to the printed resin film. A method of post-heating at a heating temperature (for example, 100 to 180 ° C.) or higher than the activation temperature of the agent layer has already been proposed prior to the present application (Japanese Patent Application No. 2001-48942). According to the printed tree Without causing deterioration of the deterioration and production efficiency content resistance by softening of the protective film during sticking of the film, it is possible to secure the adhesive strength between the printed resin film and the can body.

However, the present inventor has further examined that, in the case of a can body integrally formed from a coated metal plate in which a thermoplastic resin (protective coating) covering both the inner and outer surfaces is made amorphous, In the post-heating treatment after the printed resin film is adhered to the body, the thermoplastic resin of the protective coating is subjected to heating treatment at a relatively low temperature (100 to 180 ° C.) for a certain period of time, so that the amorphous resin becomes amorphous. The spheroidization progresses in the part that has been denatured (the part that has not been oriented and crystallized in the previous processing), and as a result, the protective film is easily damaged in the subsequent processing step, and the dent resistance ( Even when the can is shocked and dents are formed, the properties of the protective coating in that part where the adhesion and covering properties are required to be completely maintained are reduced, and fine cracks are formed in the protective coating. Easy to occur, inside When the can body after filling and sealing is subjected to an impact due to dropping, etc., the protective coating is easily scratched, and when used for highly corrosive contents such as carbonated beverages, the can body may be corroded. It turns out that there is.

An object of the present invention is to solve the above-mentioned problems. More specifically, the present invention relates to a coated metal plate whose inner and outer surfaces are coated with a protective coating made of an amorphous thermoplastic resin. After attaching the printed resin film to the integrally molded can, without causing the deterioration of the content resistance or the production efficiency due to the softening of the protective coating when the printed resin film is attached. It is an object of the present invention to prevent the printed resin film and the protective film from peeling off from the can body during the subsequent can processing without reducing the dent resistance of the protective film by the post-heating treatment.

[0017]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is to integrally form a coated metal plate whose inner and outer surfaces are coated with a protective film made of an amorphous thermoplastic resin. A method for producing a printed film-attached can body, in which a printed resin film is adhered to an outer surface side of a body portion of a heated can body via an adhesive layer, with respect to the can body, Adhesion onset temperature is 17 as an inner protective film
Using a thermoplastic resin of 0 ° C. or higher, as the adhesive layer of the printed resin film, using a resin that can be thermally bonded at 100 to 160 ° C. with the thermoplastic resin of the protective coating on the outer surface of the can, and a printed resin film When the is adhered to the body outer surface side of the can body, the temperature of the body outer surface of the can body is set to 100 to 160 ° C., and further processing is performed on the can body on which the printed resin film is adhered. Before applying, the post-heating treatment is performed in a short time at a temperature not lower than the activation temperature of the adhesive layer of the printed resin film, and not lower than the melting point of the thermoplastic resin of the protective coating covering the inner and outer surfaces of the can body. This is characterized in that the quenching treatment is performed immediately after the cooling.

The sticking start temperature (softening start temperature) of the thermoplastic resin is narrowed by a pair of pressing rolls while the thermoplastic resin film is in contact with the heated metal plate, and a linear pressure of 40 kg / cm is applied. While 100m /
At a rate of minutes, the heating temperature of the metal plate was changed little by little, and then for each sample obtained, a peel test was performed to peel the thermoplastic resin film from the thermoplastic resin film-attached metal plate. Then, the peel strength (T-peel strength) was measured, and when the strength of 1 kg / cm ² or more was obtained, the lowest temperature of the heating temperature of the metal plate was defined as the adhesion start temperature.

According to the method for manufacturing a printed film-adhered can body as described above, when the printed resin film is adhered to the outer surface of the body of the can, the inner surface of the can is protected by heating the can. Since the thermoplastic resin of the coating is not softened, the protective coating on the inner surface of the can is not discolored white and scratched even if the can is strongly pressed by the mandrel of the film sticking device, and the film There is no possibility that the protective coating on the inner surface of the can adheres to the mandrel of the sticking device and the can body does not easily come off the mandrel.

Further, since the can body after the printed resin film is adhered is post-heat-treated at a heating temperature not lower than the activation temperature of the adhesive layer of the printed resin film, the subsequent processing can be performed. At the same time, the adhesiveness between the two is sufficiently ensured so that the printed resin film does not peel off from the can body, and at a temperature equal to or higher than the melting point of the thermoplastic resin of the protective coating covering the inner and outer surfaces of the can body. By performing the post-heating treatment in a short time and then immediately quenching, the thermoplastic resin of the protective coating becomes amorphous, and as a result, the adhesion between the thermoplastic resin of the protective coating and the metal surface of the can body is obtained. And the processing resistance of the protective coating is improved, and the dent resistance is also improved.

That is, even if the thermoplastic resin of the protective coating covering the metal plate is made amorphous before being formed into a can, it is partially oriented by being stretched in the subsequent step of forming the can. Although crystallized, in the step of post-heating treatment on the can after sticking the printed resin film,
Heat treatment in a short time at a temperature equal to or higher than the melting point of the thermoplastic resin and immediately quenching immediately melts the thermoplastic resin of the protective coating and immediately turns it amorphous, so that it is amorphous before the post heat treatment. The entire protective coating of the can is made amorphous without the spheroidization progressing in the as-modified part (the part that has not been oriented and crystallized by the previous processing) and the dent resistance is not reduced. It is possible to improve the processing resistance of the protective coating and the adhesion to the metal surface of the can body.

As a result, the can body is then subjected to severe processing (for example, processing such as forming a curled portion or a threaded portion on the mouth and neck of a bottle-shaped can, and opening the barrel end of a cylindrical can. ), The printed resin film is peeled off from the can, or the protective coating of the thermoplastic resin is applied to the can. It does not peel off from the metal surface,
Further, even when an impact such as dropping is given after filling and sealing the contents of the can body, the inner surface of the can is not corroded due to a decrease in the dent resistance of the protective coating.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing a printed film-adhered can according to the present invention will be described in detail with reference to the drawings, using an embodiment applied to the manufacture of a bottle-shaped can.
FIG. 1 shows a bottle-shaped can as an example of a can body manufactured by the method of the present invention, and FIG. 2 schematically shows an example of a manufacturing process for manufacturing the bottle-shaped can shown in FIG. 3 shows each step of forming the cervix and neck in the top dome forming step of the manufacturing process shown in FIG. 2, and FIG. 4 shows (A) a coated metal plate and (B) a printed metal plate. It is a figure which shows each lamination structure of each cross section about a resin film and the trunk | drum of the (C) printed film sticking can body. It should be noted that the dimensions of each part shown in FIG. 4 are merely schematically shown regardless of the actual dimensions.

As shown in FIG. 1, a bottle-shaped can manufactured by the method for manufacturing a printed film-adhered can body according to the present embodiment has an arc-shaped vertical section upward from a large-diameter cylindrical body 2. A small-diameter cylindrical threaded mouth-neck portion 4 is integrally formed via a dome-shaped shoulder portion 3 of the above, and the lower end opening of the body portion 2 is tightly closed by tightly fastening a bottom lid 5. On the outer surface of the body 2, a printed resin film on which a desired multicolor printing is performed in advance is attached to a portion surrounded by oblique lines.

An example of the manufacturing process of the bottle-shaped can will be schematically described. A metal plate 1 as shown in FIG.
1. A coated metal plate 10 on which protective films 12 and 13 made of thermoplastic resin in an amorphous state are formed on both surfaces is used as a material, and a lubricant (preferably, on both surfaces (on the protective films 12 and 13)) is used. After applying a high-temperature volatile lubricant), as shown in FIG. 2, first, in a cup forming step, a blank obtained by punching a coated metal plate into a disk shape is drawn and formed into a cup shape. In the next can body forming step, the cup is subjected to at least one or more redrawing, stretching, or ironing to form a cylindrical body having a small diameter and a thin bottom.

In the top dome forming step, the drawing process is performed a plurality of times (three times in FIG. 2) on the bottom side of the cylindrical can body having a bottom so that the inclined shoulder portion and the unopened portion are formed. After molding the mouth and neck (bottomed cylinder), in the lubricant removal process,
Remove the lubricant from at least the outer surface of the can body whose mouth and neck are not opened and the lower end of the body is opened (the temperature at which the outer surface of the can body is washed away with hot water or the like, or in the case of a high-temperature volatile lubricant, is volatilized) Heat the can body as described above), and in the trimming step, trim the opening end side of the body part opposite to the mouth and neck to make the can body a predetermined length, and then proceed to the printed film sticking step Send out.

In the step of attaching a printed film, desired printing is performed in advance by a gravure printing method or the like on the surface of a resin film such as a biaxially stretched polyester film having good printability and excellent heat resistance and abrasion resistance. And 100 ~
A printed resin film provided with an adhesive layer that can be adhered at a temperature of 160 ° C. is cut into a film sheet slightly longer than the length of the body of one can and cut into 10 pieces in advance.
Affixed to the cylindrical body of a can body (bottle-shaped can with the mouth, neck, shoulder, and body integrally formed) heated to 0 to 160 ° C., and then subjected to post-heating treatment (after film attachment) In the step of heat treatment of the can body) at a temperature not lower than the melting point of the thermoplastic resin of the protective coating covering the inner and outer surfaces of the can body for a short time (for example, 240 to
By heating immediately at a temperature of 270 ° C. for 10 to 50 seconds) and immediately quenching, the protective coating of the thermoplastic resin covering the inner and outer surfaces of the can is made amorphous.

Next, in the screw / curl forming step, first,
After opening the mouth and neck by trimming the closed end of the unopened mouth and neck, the open end is formed into an annular curl by external winding, and then the cylindrical shape below the curl A thread portion for screwing the cap is formed on the peripheral wall, and an annular concave bead portion for fixing the lower end portion of the break band of the pill fur proof cap is formed at a slight interval below the thread portion.

Then, in a neck / flange forming step, a neck-in process and a flange process are sequentially performed on a lower end opening end of the body portion opposite to the mouth / neck portion, and then a bottom cover winding process (not shown) is performed. In the above, by using a seamer (can lid winding machine), the bottom lid of another member made of a metal plate material is integrally fixed to a flange formed at the lower end opening of the body by a double winding method, A bottle can as shown in FIG. 1 is completed.

The respective materials used in the method for manufacturing a printed film-attached can of this embodiment by the above-described manufacturing steps will be described in detail. The metal plate for integrally forming the can is shown in FIG. As shown in FIG. 1A, a coated metal plate 10 in which protective films 12 and 13 made of a thermoplastic resin are laminated on both surfaces of a metal plate 11,
1 is a pure aluminum plate or an aluminum alloy plate subjected to a surface treatment such as a chemical conversion treatment, or a metal plate such as a tin plated steel plate, an ultra-thin tin plated steel plate, a nickel plated steel plate, a galvanized steel plate, or the like. Further, a thin sheet of a metal sheet for cans such as a surface-treated steel sheet, an electrolytic chromic acid-treated steel sheet, and an organic-inorganic chemical conversion-treated steel sheet further subjected to a chemical conversion treatment can be used as appropriate.

Both sides of metal plate 11 (inner side of can and outer side of can)
The thermoplastic resin to be coated as the protective coatings 12 and 13, respectively, is not particularly limited. Examples thereof include polyolefin resins such as polyethylene, polypropylene, ethylene / propylene copolymer, and modified olefin, polyethylene terephthalate, and polyolefin resin. Polyester resins such as butylene terephthalate, polyethylene naphthalate, ethylene terephthalate / isophthalate copolymer, ethylene terephthalate / adipate copolymer, butylene terephthalate / isophthalate copolymer, ethylene naphthalate / terephthalate copolymer, polycarbonate resin, nylon Resins and mixed resins of two or more thereof can be suitably used.

The protective coatings 12 on both sides of the metal plate 11,
As for 13, the same thermoplastic resin may be used on both surfaces, but different thermoplastic resins may be used on both surfaces. The mode of coating is not limited to a single layer, and different types of resin may be used. In any case, in the method of the present embodiment, when the printed resin film is stuck to the can body, the printed resin film is pressed by the mandrel of the film sticking device, and thus may be damaged. Or, in order not to adhere to the mandrel and make it difficult to remove the can body from the mandrel, at least the protective coating 12 on the inner surface side of the can body,
A thermoplastic resin having an adhesion start temperature of 170 ° C. or more is used.

In the present embodiment, as shown in FIG. 4B, the top coat layer 21 / thermoplastic resin is applied to the printed resin film adhered to the outer surface of the body of the can body (bottle-shaped can). The laminated film 20 is used in which the film layer 22 / printing ink layer 23 / adhesive layer 24 is laminated in this order.
Top coat layer 21 and printing ink layer 23 on both sides of
The printing ink layer 23 is covered with the top coat layer 21 on the same side (outer side) of the thermoplastic resin film 22 without being limited to those formed separately on the outer surface side and the inner surface side. It may be formed as an appropriate laminated structure, for example, it may be formed.

The thermoplastic resin film 22 serving as the base material of the printed resin film 20 serves as a holding portion for the printing ink layer 23, and basically, a transparent resin film may be used. Desirable (in the case of a type in which a printing ink layer is formed on the inner surface side of the thermoplastic resin film and a top coat layer is formed on the outer surface side, the clarity and gloss of the printed appearance of characters and patterns to be printed are ensured. In order to increase the adhesive strength between the can body and the amorphous resin of the protective coating, it must have heat resistance enough to withstand post-heating treatment for amorphizing the thermoplastic resin of the protective coating. Since it is necessary, it is preferable to use a film of a polyester resin or a nylon resin, and in particular, from the viewpoint of transparency and heat resistance, a biaxially stretched film of oriented and crystallized polyester resin. Arm is optimal.

As the polyester resin used as the thermoplastic resin film 22 of the printed resin film 20,
Specifically, homopolymers such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polyethylene isophthalate; copolymerized polyesters such as ethylene terephthalate / isophthalate copolymer, butylene terephthalate / isophthalate copolymer; There are various resins such as a blend resin of terephthalate and polyethylene isophthalate and a blend resin of polyethylene terephthalate and polybutylene terephthalate.

As shown in FIG. 4C, after the printed resin film 20 is attached to the can 1A,
In order to prevent the printed resin film 20 from being greatly damaged when performing a post-heating treatment for amorphizing the thermoplastic resin of the protective coatings 12 and 13 covering both the inner and outer surfaces of the printed resin film, The thermoplastic resin 22 serving as the base material of the finished resin film 20 has a melting point close to the melting point of the thermoplastic resin laminated on the inner and outer surfaces of the can body as the protective coatings 12 and 13 (about 5 ° C. may be lower). It is necessary to select a polyester resin having a high melting point or a higher melting point. As such a polyester resin, polyethylene terephthalate is most preferable in terms of relatively high heat resistance and economical efficiency.

As for the top coat layer 21 which is the uppermost layer of the printed resin film 20, it is possible to prevent the resin film 20 from being damaged due to insufficient slipperiness of the can body (film-attached can body) and to prevent the resin film 20 from being retorted. Physical change of
That is, it is provided in order to prevent a change in crystallinity and a change in optical characteristics due to water content. In any case, the purpose is to ensure the appearance of the printed finish, so that it has good slipperiness and retort treatment resistance. Not only that, it is necessary that the coating layer be further colorless and transparent. As such a top coat layer 21, a thermosetting resin paint, an electron beam curable resin paint, an ultraviolet curable resin paint, or the like is used. can do. Further, a lubricating agent such as silicon or wax may be added in order to further improve the lubricating property.

The printing ink layer 23 is not particularly limited since characters and designs are applied by printing, but inks using a thermosetting urethane resin as a binder are generally used. The printing method includes gravure printing, flexo printing, offset printing, etc.
Various printing methods can be selected as appropriate. However, when it is desired to print characters and designs with rich colors and beautiful colors by using a large number of colors, it is preferable to use a gravure printing method.

That is, by applying a printed resin film to the body of the cylindrical can body,
It is possible to apply gravure printing, which has high printing clarity and excellent gradation expression (it is practically difficult to apply gravure printing directly to the outer surface of the cylindrical body), and thereby, the cylindrical body Compared to the case where dry offset printing is directly performed on the outer surface, a luxurious print design with a deeper depth can be provided.

The adhesive layer 24 provided on the lowermost layer of the printed resin film 20 is basically made of an adhesive which can be easily attached to the outer surface of the body of the can by applying pressure and heat. And thermosetting adhesives such as unsaturated polyester resins, isocyanate resins, amino resins, polyurethane resins, epoxy resins, and acrylic resins. In particular, polyester-isocyanate-amino adhesives, polyester-epoxy-amino Adhesives, epoxy-phenol adhesives, and epoxy-amino adhesives can be preferably used.
Adhesives that combine heat curing and electron beam curing can also be used. Also, not only the adhesive of the resin composition as described above,
Additives (such as white pigments made of inorganic pigments such as titanium oxide and mica, dyes, adhesion-imparting agents, anti-blocking agents, etc.) can be added to such a resin composition.

However, in any case, according to the method of the present embodiment, when the printed resin film 20 is adhered to the can body, the thermoplastic resin of the protective coating 12 on the inner surface side of the can is caused by the mandrel of the film adhering device. The heating temperature of the can is limited so that the protective film 12 is not damaged by the pressure applied to the can and the protective coating 12 does not stick to the mandrel and the can is difficult to remove from the mandrel.
The adhesive used as the zero adhesive layer 24 must be an adhesive that can be bonded at a temperature (100 to 160 ° C.) lower than the temperature at which the thermoplastic resin of the protective coating 12 on the inner surface of the can starts to adhere. It is.

As described above, as the printed resin film 20, a printing ink layer 23 is formed on the same surface as the top coat layer 21, and the top coating layer 21 is coated on the printing ink layer 23. In this case, the side (back side) that contacts the can body is formed of a thermoplastic resin having a low melting point, and the opposite side (front side) is used as the thermoplastic resin film 22 serving as the base material. ) Uses a two-layered thermoplastic resin film formed of a high-melting thermoplastic resin, so that the low-melting thermoplastic resin (protection of the inner surface of the can) can be applied without applying and drying an adhesive. 100 to 160 lower than the adhesion start temperature of the thermoplastic resin of the coating film
The adhesive layer 24 can be made to function as a thermoplastic resin layer (a resin that can be heat-bonded at a temperature of ° C.).

In such a case, the thermoplastic resin having a low melting point includes acid-modified polyolefin, ionomer, polyolefin resin such as ethylene-vinyl acetate copolymer, ethylene terephthalate / isophthalate copolymer, ethylene terephthalate / adipate copolymer. Copolymerized polyester resins such as a copolymer, an ethylene terephthalate / sebacate copolymer, a butylene terephthalate / isophthalate copolymer, and a copolymer of two or more dicarboxylic acids and two or more diols; A blend resin in which two or more kinds of resins are mixed can be used.

In this manner, a low-melting-point thermoplastic resin layer serving as an adhesive layer is formed when the thermoplastic resin film serving as the base material is formed, and a printing ink layer is formed on the same side as the top coat layer. When a printed resin film is manufactured by a back printing method in which an adhesive layer is formed on a printing ink layer by forming a film (top coat coating, drying, film winding. Unwinding the film, printing and bonding Coating, drying, and film winding.) Compared to printing and drying, adhesive is not applied and dried. Since it is only necessary to form the coat layer and wind it on a reel, the production speed of the printed resin film can be increased, and the production efficiency can be increased. Also,
The transparency of the resin for producing the thermoplastic resin film does not matter (it may be opaque).

The method for producing a printed film-adhered can of this embodiment, which is carried out using the above-described materials, will be described in detail below. First, a coated metal plate to be a metal plate for can-making By laminating a thermoplastic resin film on both sides of the strip-shaped metal plate (the inner surface of the can and the outer surface of the can), both surfaces of the metal plate 11 are made of thermoplastic resin as shown in FIG. A strip-shaped plate material of the coated metal plate 10 covered with the resin protective coatings 12 and 13 is manufactured and prepared. At this time, as the protective coating 12 on the inner surface of the can, a thermoplastic resin having an adhesion initiation temperature of 170 ° C. or more is used. As the protective coating 13 on the outer surface of the can, a thermoplastic resin having an adhesion initiation temperature of 180 ° C. or more is used. Uses resin.

A protective coating 1 made of a thermoplastic resin on a metal plate 11
As a method of laminating as 2, 13, besides a method of directly thermally bonding a thermoplastic resin film formed in advance to a metal surface (surface treated surface) of a preheated metal plate,
An adhesive primer layer or a curable adhesive layer or a thermoplastic resin layer having good thermal adhesion (for example, a two-layer thermoplastic resin in which the lower layer has a low melting point and the upper layer has a high melting point) (In the case of using a film), an appropriate method such as a method of thermally bonding to a metal surface of a metal plate through a method or a method of extruding a molten thermoplastic resin from a T-die onto a preheated metal plate and directly bonding the same is adopted. it can.

As described above, the thermoplastic resin is laminated on both surfaces of the metal plate 11 as the protective coatings 12 and 13, and the coated metal plate 10 is formed into a can body at a stage before forming the can body at the subsequent stage. From the viewpoint of improving processability and adhesiveness (adhesion between the thermoplastic resin and the metal plate surface), after the coated metal plate 10 is once heated to melt the thermoplastic resin (for example, the coated metal Rapid cooling (for example, by passing the board through water) allows the protective coatings 12, 13
Is made amorphous.

Prior to processing, the coated metal plate 10 in which the thermoplastic resin of the protective coatings 12 and 13 has been made amorphous is coated on the protective coatings 12 and 13 of the thermoplastic resin on both surfaces thereof, for example, before processing. One or more lubricants such as normal butyl stearate, liquid paraffin, petrolatum, polyethylene wax, edible oil, hydrogenated cooking oil, palm oil, synthetic paraffin, dioctyl sebacate, etc. In the cup forming step, blanks are punched into blanks for each can and drawn into a cup by drawing using the coated metal plate coated with the agent as a material. As a specific example, a blank punched into a disk having a diameter of 170 mm is formed into a blank having a height of 48.3 mm and an outer diameter of 100 m.
m is drawn into a cup shape.

In the can body forming step, the cup thus formed is further subjected to two re-drawing processes, one of which is subjected to bending and stretching (stretching), and thereafter, is subjected to ironing. By applying, it is formed into a bottomed cylindrical can body having a smaller diameter, a higher height and a thinner body than the original cup shape. As a specific example, a cup having a height of 48.3 mm and an outer diameter of 100 mm,
It is molded into a bottomed cylindrical can body having a height of 171.5 mm or more and an outer diameter of 65.9 mm.

Then, in the top dome forming step of the bottomed cylindrical can body formed as described above, first, as shown in FIG. A drawing die 51 having a shape of a convex curved surface which is a connecting portion between a portion and a shoulder portion) on the inner surface side of the distal end portion, a pusher 52 having a shape of a curved surface lower than the shoulder portion on the outer surface side of the distal end portion, The bottom portion 41 is punched by the punch 53 and the die 51 from the body portion 2 while the corner portion of the can bottom (the corner portion between the body portion 2 and the bottom portion 41) is wrinkled by the die 51 and the pusher 52. In addition to forming a small-diameter bottomed cylindrical portion 42 by drawing, the shoulder lower curved surface 31 is formed below the bottomed cylindrical portion 42.

In the portion of the bottle-shaped can that becomes the lower curved surface 31 of the shoulder, a punch whose outer peripheral surface is a curved surface having a large radius of curvature is formed at the time of or after molding of the cylindrical can body having a bottom (see FIG. (Not shown), and is preformed at the corner of the bottom of the can by using a die 53 and a pusher 52. The small diameter bottomed cylindrical portion 42 may be formed by drawing.

Next, the newly drawn small-diameter bottomed cylindrical portion 42 is connected to a tapered surface whose longitudinal section approximates the tangent of a vertical section circular arc of a virtual curved surface following the shoulder lower curved surface 31 by a substantially straight line. In a state where wrinkles are suppressed by using a redrawing die 54 and a wrinkle pressing pusher 55 provided in the portion, a redrawing punch 56 is used to redraw into a bottomed cylindrical shape 43 with a smaller diameter. Such redrawing is repeated once (the die 54 and the pusher 55 used here).
The inclination angle of the tapered surface with respect to the can axis becomes larger than that at the time of the previous redrawing. Also, the die 54 and the pusher 55
And the inner diameter or outer diameter of the punch 56 becomes smaller than that in the previous redrawing. ), The diameter of the bottomed cylindrical portion 43 is adjusted
The diameter is reduced until it becomes substantially the same as the diameter of the body (as a specific example, the body is reduced to a mouth and neck having an outer diameter of 28 mm for a body having an outer diameter of 65.9 mm).

In the present embodiment, redrawing (processing) is performed twice in forming the mouth and neck and the shoulder, but the outer diameter of the mouth and neck to be formed is determined. When the diameter of the cylinder is about 1/2 or more of the outer diameter of the body of the can, the re-drawing for re-drawing the small-diameter bottomed cylindrical portion formed by drawing to a smaller-diameter bottomed cylindrical portion may be performed once. For example, when the outer diameter of the body of the can is 65.9 mm and the expected outer diameter of the mouth and neck is about 38 mm, re-drawing only needs to be performed once.

Next, by repeating such drawing and redrawing, the shoulder with the original shoulder curved surface 31 and the two tapered surfaces 32 and 33 continuing from the original curved surface are finally formed. A pair of reshaping tools (die 57 and pusher 58) having the surface shape of the shoulder curved surface that is stretched out to form a continuous smooth shoulder 3
In the final stage of the top dome forming process, the upper neck is formed twice (see FIG. 2). The diameter of the upper half is reduced and the diameter of the upper neck is reduced by a quarter.

In the lubricant removing step, the lubricant such as normal butyl stearate, liquid paraffin, synthetic paraffin and the like applied to both the inner and outer surfaces of the can body is removed from the top dome shaped can body as described above. To do so, for example, a known degreasing agent and water or hot water or the like are sprayed onto the inner and outer surfaces of the can body to wash and remove the lubricant, or
The can body is heated to about 200 to 300 ° C. (preferably 255 to 30 ° C.).
0 ° C.), the lubricant is volatilized by heating to a high temperature, and the can body from which at least the outer lubricant has been removed in the lubricant removing step is subjected to a trimming step in a lower end opening end side of the body. After trimming the can body to a predetermined length,
It is sent to the printed film sticking process.

When a cleaning method is used to remove the lubricant, a can washer used in the degreasing / cleaning process of the squeezing and ironing can be used, and when the lubricant is volatilized, Hot air may be blown while the can body is placed on a net conveyor and transported with the opening side down. When the thermoplastic resin of the protective film covering the inner and outer surfaces of the can body is made amorphous again in the lubricant removing step, the temperature of the hot air is set to a temperature higher than the melting point of the thermoplastic resin. After blowing hot air, cool air (2
0 ° C. or less, preferably 15 ° C. or less).

On the other hand, separately from the production of the bottle-shaped can body as described above, a printed resin film to be adhered to the body of the can body is formed on a thermoplastic resin film band-like film as a base material. For example, after applying and drying a top coat on one side, printing and drying on the opposite side, and then applying and drying an adhesive so as to cover the printing ink layer, FIG. As shown in (B), a strip-shaped film of the printed resin film 20 having the adhesive layer 24 is manufactured and prepared. At this time, as the adhesive layer 24 contacting the outer surface of the body of the can, the protective coating 1 on the inner surface of the can is used.
Temperature lower than the tacking onset temperature of the thermoplastic resin of No. 2 (10
(0 to 160 ° C.).

The strip-shaped printed resin film manufactured as described above is cut into a width corresponding to one can, is once wound on a reel, and immediately before being adhered to the can body, the size of each printed resin film is determined. In the step of sticking the printed resin film to the can body, in the step of sticking the printed resin film to the can body, the heated can body is cut by one can every one can by a conventionally known appropriate film sticking apparatus. Is adhered by pressing the adhesive layer formed on the lowermost layer thereof against the outer surface side of the body of the can body and thermally bonding the sheet.

That is, in this embodiment, at least the lubricant on the outer surface side is removed in the lubricant removing step, and the can body trimmed to a predetermined length in the trimming step is mounted on the mandrel of the film sticking apparatus. In the film sticking station of the apparatus, the temperature is set so that the temperature is equal to or higher than the bonding temperature of the adhesive layer of the printed resin film.
A sheet of printed resin film is applied to the can body heated to 00 to 160 ° C. and attached to the mandrel, while the adhesive layer side of the sheet is in contact with the outer surface of the can body, and is attached by a sticking roll. 1961-923N (200-400
kgf), preferably 1961 to 2452 N
By pressing with a pressing force of (200 to 250 kgf), the printed resin film is thermally bonded to the outer surface of the body of the can via an adhesive layer.

Specifically, in a film sticking apparatus,
At a can supply station of the apparatus, pressurized air is blown to the bottom outer surface side of the can body to any of the mandrels attached at equal intervals around the rotating body provided in the apparatus main body. After moving the can body to the mandrel and vacuuming it through the air hole of the mandrel to completely cap the can body on the mandrel, while transporting the can body by the mandrel that moves in the circumferential direction as the rotating body rotates. After the printed resin film sheet is thermally bonded to the outer surface of the cylindrical body of the can by the pressing force of the bonding roll at the film bonding station of the apparatus, the air holes of the mandrel are formed at the can discharge station of the apparatus. The can body is discharged from the mandrel to the discharge conveyor by blowing out pressurized air from the container, where the can body is conveyed by magnet or vacuum suction. It is conveyed in a state of being adsorbed to the A.

For such a film sticking device,
For example, JP-A-8-1778 and JP-A-9-295
No. 639, Japanese Unexamined Patent Application Publication No. 10-683, etc., are basically conventionally known. When such an apparatus is diverted to a bottle-shaped can, it is different from a conventional cylindrical can. In comparison, it is only necessary to change the specific shape and length of the mandrel, or to perform a simple type change such as changing the interval between the mandrel and the discharge conveyor.

In the method of the present embodiment, the post-heating treatment (heating treatment of the can body after the film is adhered) is performed on the can body having the printed resin film adhered thereto and discharged from the film adhering apparatus. Before the can body is further processed (screw / curl forming or neck / flange processing), the inner and outer surfaces of the can body must be at or above the activation temperature (100 to 160 ° C.) of the adhesive layer of the printed resin film. Melting point of the thermoplastic resin of the protective coating that is applied (The onset temperature of the adhesive of the thermoplastic resin of the protective coating is 170 ° C or more on the inner surface of the can, and the adhesive onset temperature of the thermoplastic resin of the protective coating on the outer surface of the can is 180 ° C or more. At the above temperature, the can body is heated in a short time and then immediately cooled.

More specifically, in the post-heating treatment step, the can body on which the printed resin film is adhered is transported by a vacuum conveyor with the body opening end facing down and passed through the oven. Then, in the heating zone, the hot air blown from above to below the can body causes the temperature of the protective coating covering the inner and outer surfaces of the can body to be equal to or higher than the melting point of the thermoplastic resin for a short time (specifically, 200 to 270). After heating at a temperature of 10 ° C. for 10 to 50 seconds), in the cooling zone next to the heating zone, it is rapidly cooled by cold air blown downward from above the can body.

Then, as shown in FIG. 2, first, in the screw and curl forming step, the upper end small diameter portion of the mouth and neck portion is applied to the can body subjected to the post-heating treatment (and the quenching treatment). After opening the mouth and neck by trimming, an outer curl portion, a screw portion, and a concave bead portion are sequentially formed on the opened mouth and neck portion. Neck-in processing and flange processing are sequentially performed on the lower end opening end of the body part on the side opposite to the part, and although not shown, formed in the lower end opening of the can in the bottom cover winding step. A bottle-type can that can be filled with contents is obtained by double-tightening the bottom cover of a separate member to the flange portion with a seamer (can lid tightening machine).

According to the method for producing a printed film-adhered can body of the present embodiment as described above, when the printed resin film is adhered to the outer surface of the body of the can body, the heating (10
Since the thermoplastic resin (adhesion start temperature is 170 ° C. or more) of the protective coating on the inner surface side of the can is not softened by heating to 0 to 160 ° C., even if the can body is strongly pressed by the mandrel of the film sticking apparatus. The protective coating on the inner surface of the can does not discolor and become scratched, and the protective coating on the inner surface of the can adheres to the mandrel of the film sticking device, making it difficult for the can body to come off from the mandrel. Absent.

Before further processing (screw / curl forming or neck / flange processing) is performed on the can body after the printed resin film is adhered, the can body is subjected to a post-heating treatment step.
Activation temperature of the adhesive layer of the printed resin film (100
-160 ° C) or higher and the melting point of the thermoplastic resin of the protective coating (170 ° C or higher on the inner surface of the can, 180 ° C on the outer surface of the can)
Above) at a temperature above (200-270 ° C.) for a short time (10
By performing the quenching treatment immediately after the heat treatment after the heating treatment, the adhesive layer can be activated, the adhesiveness between the printed resin film and the can can be improved, and the Without lowering the dent property, the thermoplastic resin of the protective coating can be made amorphous,
The processing resistance of the protective film and the adhesion to the metal surface of the can body can be improved.

That is, even if the thermoplastic resin of the protective coating covering the metal plate is amorphized before being formed into a can, it is partially oriented by stretching in the subsequent can forming step. While being crystallized, the thermoplastic resin of the protective film is once melted and made amorphous by immediately post-heating at a temperature equal to or higher than the melting point of the thermoplastic resin and then immediately quenching. Therefore, the oriented and crystallized portion of the protective film can be surely made amorphous, and the portion of the protective film that remains amorphous (the portion that has not been oriented and crystallized by the previous processing) Also, the amorphous state is maintained. As a result, the dent resistance does not decrease due to the spheroidization of the thermoplastic resin of the protective film.

As described above, when the printed resin film is adhered, the protective film is softened without deteriorating the resistance to contents and the production efficiency. It is necessary to improve the adhesion between the printed resin film and the can body before entering the screw / curl forming step or the neck / flange forming step without reducing the dent resistance of the protective coating by post-heating treatment. In addition, by improving the processing resistance of the protective coating and the adhesion to the metal surface of the can body, it is possible to form a curl or screw on the mouth and neck without damaging the protective coating. It is practically possible to perform a proper processing or to perform a neck flange processing on the opening end of the body without peeling off the printed resin film or the peeling.

Although the embodiment of the method for producing a printed film-adhered can of the present invention has been described above, the present invention is not limited to the above-described embodiment. The present invention is not limited to the can body in which the bottom side of the bottomed cylindrical can is formed into the mouth and neck and the shoulder as shown in the embodiment, and three-stage neck-in processing is performed on the opening end of the body of the cylindrical can. It can also be applied to cans and the like that apply a large smooth neck-in process with a degree of diameter reduction equal to or greater, and also for a printed resin film to be adhered to the body of the can, a top coat layer and Not only a printed resin film consisting of a thermoplastic resin film layer, a printing ink layer, and an adhesive layer, but also a printed resin film in which layers such as a hologram forming layer and a metal deposition layer are appropriately formed. To implement Possible and so, it goes without saying as it can be changed as appropriate.

[0070]

According to the method for producing a printed film-adhered can body of the present invention as described above, when the printed resin film is adhered to the outer surface of the body of the can, the inner surface of the can is exposed. By not softening the thermoplastic resin of the protective coating, the protective coating on the inner surface of the can is damaged and the content resistance is deteriorated, and the protective coating on the inner surface of the can is adhered and the can hardly comes off from the mandrel. In addition to preventing the production efficiency from deteriorating, the post-heating treatment is performed on the can body on which the printed resin film is adhered, so that the thermoplastic resin of the protective coating becomes amorphous. By reducing the dent resistance of the protective coating, it is possible to sufficiently secure the adhesiveness between the printed resin film and the can body,
In addition, the processing resistance of the protective coating and the adhesion to the metal surface of the can body can be improved, preventing the printed resin film and the protective coating from peeling or scratching from the can body during subsequent processing. can do.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional side view showing a bottle-shaped can as an example of a can manufactured by the method for manufacturing a printed film-adhered can according to the present invention.

FIG. 2 is an explanatory side view schematically showing an example of a manufacturing process for manufacturing the bottle can shown in FIG.

FIG. 3 is an explanatory side view and a cross-sectional view showing a forming process of a mouth-neck portion and a shoulder portion in a top dome forming process in a manufacturing process of the bottle-shaped can shown in FIG. 2;

FIG. 4 shows (A) a coated metal plate and (B) a printed resin film which are materials for manufacturing the bottle-shaped can shown in FIG. 1, and (C) a body of the manufactured bottle-shaped can. Sectional drawing which shows the laminated structure in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Printed film sticking can body 1A Can body (can body excluding printed resin film) 2 Body (of can body) 10 Coated metal plate 12 Protective coating on inner surface of can (protective coating of thermoplastic resin) 13 Protective coating on outer surface of can (protective coating of thermoplastic resin) 20 Printed resin film 24 Adhesive layer (of printed resin film)

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 3E061 AA24 AB13 AC09 BA01 BB06 BB14 DA02 DB09 DB11 4F100 AB01A AB10A AB31A AK01B AK01C AK01D AK04B AK04C AK07B JAK12C EB07B12B12B12B12B12E JL13B

Claims (2)

[Claims] 1. A can body which is integrally formed from a coated metal plate whose inner and outer surfaces are coated with a protective coating of an amorphous thermoplastic resin, is provided on a body outer side of a heated can body. In the method for producing a printed film-adhered can body in which a printed resin film is adhered via an adhesive layer, as a protective film on the inner surface side of the can, a thermoplastic resin having an adhesion initiation temperature of 170 ° C or more is used. Used as the adhesive layer of the printed resin film, the thermoplastic resin of the protective coating on the outer surface of the can and 10
Using a resin that can be thermally bonded at 0 to 160 ° C., and when attaching the printed resin film to the outer surface of the body of the can, the temperature of the outer surface of the body of the can is set to 100 to 160 ° C., The can body after the printed resin film is adhered is at or above the activation temperature of the adhesive layer of the printed resin film, and is at or above the melting point of the thermoplastic resin of the protective coating covering the inside and outside surfaces of the can body. A post-heating treatment in a short time and then a quenching treatment immediately after the heating at the temperature of (1). 2. A can body to which a printed resin film is pasted is subjected to a post-heating treatment at a temperature of 200 to 270 ° C. for 10 to 50 seconds and then immediately quenched. The method for producing a printed film-adhered can according to claim 1.