JP2006248573A - Method of producing printed film bonded can body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of producing a printed film bonded can body, which contributes to improvement in printing efficiency and reduction in production cost, and is free from an inconvenience when heated. <P>SOLUTION: The method of producing the printed film bonded can body has a substrate treatment step, a printing step, a film bonding step, and an ultraviolet irradiation step. In the substrate treatment step, a substrate layer 11 is formed on a surface other than one surface of a thermoplastic resin film 2, on which a clear coat layer is formed. In the printing step, a print layer 12 in a tentatively cured state is formed on a surface of the substrate layer by ejecting ultraviolet curing ink from an ink-jet printer to stick the ink to the surface of the substrate layer, and an adhesive is applied to the print layer, followed by heating and drying the print layer, thereby forming the printed film. In the film bonding step, the printed film is bonded on a can body section of the heated cylindrical can body 1. In the ultraviolet irradiation step, after bonding of the printed film on the can body section, ultraviolet rays are applied to the printed film to permanently cure the ultraviolet curing ink. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a printed film-attached can body in which a printed resin film printed using an ultraviolet curable ink is attached to the outer surface of a can body of a metal can body.

  As a metal can currently distributed as a beverage can or a food can, a seamless metal can with an integrated bottom made of steel or aluminum, and a bottom lid and a canopy (including an easy open can lid) are wrapped around both ends of the can body There are known three-piece cans and reseal cans such as bottle-type cans in which a screw part is provided at the opening of the can body and the cap is wound to give the cap a reseal function.

  These various types of cans are decorated with decorations such as figures and trademark characters from the viewpoint of anticorrosion and design. Generally, as a method of applying such decorations to the can body, For example, Patent Document 1 or Patent Document 2 discloses a technique for attaching a printed film to an outer surface of a can body of a two-piece can formed integrally with a bottom portion and having no seam portion on its side surface through an adhesive layer. As disclosed, many proposals have already been made, and commercialization has already been implemented by the applicant.

  Also, like a soldering can, a welding can or an adhesive can, it is formed by rounding a metal plate and joining both ends in the circumferential direction, and bonding it to the can body of a three-piece can having a seam on the side surface The technical idea itself for adhering a printed film (film label) provided with an agent layer is disclosed in Patent Document 3.

  Furthermore, the varnish is applied to the outer surface side of the film, printing is performed on the can body side of the film, the adhesive is applied to the printing surface side and dried, and the laminate is laminated with the end on the outer periphery of the can body. This is disclosed in Patent Document 4. In this Patent Document 4, a flexographic printing method, a flat plate printing method, a screen printing method, a gravure printing method, an electrophotographic printing method, an ink jet printing method, etc. are used to preliminarily decorate a PET film and apply an adhesive to the outer surface of the can body It is also described that the sticking is performed via

  Recently, in order to cope with the diversification of products due to changes in consumer trends and needs, or quick and timely product shipments, there is a demand for a form of production / shipment in a variety of products and small lots. In order to satisfy the requirements of such manufacturing / shipping form, a heat-shrinkable film already decorated by printing or a heat-shrinkable tube formed in a cylindrical shape is wrapped around or covered with a can. A heat-shrinkable metal can is described in Patent Document 5.

Furthermore, using sublimation ink, characters or figures are printed on a medium such as paper or plastic film by ink jet printing method or laser printing method, and the printed surface is wound so as to be in contact with the surface of the metal can. Patent Document 6 describes a method in which a medium is heated in an oven or the like to closely adhere and fix the ink to a metal can, and then the medium is removed to obtain a printed metal can.
JP-A-3-230940 Japanese Patent Laid-Open No. 10-683 JP-A-52-24789 JP 2003-54567 A Japanese Patent Laid-Open No. 9-226738 JP 2001-315495 A

  As described above, with the progress of multi-product and small-lot production of products, demands for product delivery time and cost are increasing, and quick and timely product shipment is required with short delivery time. In order to meet these requirements, for example, a method in which a printed film is manufactured separately in advance and a metal can body is manufactured by coating the printed film according to a customer order is advantageous in terms of shortening the delivery time of the product. It is. However, a large number of types and quantities of printed films must be prepared in advance before ordering from a customer, and they are held in stock, which is not economically satisfactory.

  In addition, when a can body is manufactured by sticking a film printed using a printing plate contact type printing method such as a gravure printing method to a can body, an original for printing must be manufactured. In addition, there is a problem that the plate making cost is high and the plate changing operation such as plate changing or ink changing must be performed for each lot, and the printing efficiency is lowered.

  On the other hand, if a non-contact printing method such as the electrophotographic printing method and the ink jet printing method exemplified in Patent Document 4 and Patent Document 5 described above is used, it is not necessary to produce an original plate, and the plate-making cost can be reduced. Therefore, it is possible to reduce the setup change work for each lot, and it is possible to reduce the product cost and improve the printing efficiency in response to the multi-product / small-lot production. As for the ink jet printing method, there has been proposed an ink jet image forming method in which an ultraviolet curable ink is ejected onto a surface to be printed by an ink jet head, and the ink is cured by irradiating the ultraviolet ray to form an image. Unlike inkjets using water-based inks, good images can be obtained. Therefore, practical application is expected mainly for non-absorbing media such as plastic films.

  However, in such a non-contact type printing method, there is a problem that the printing quality becomes unstable due to ink bleeding on the film, and the contents are put on the can body in order to sterilize the contents of the can body. During the sterilization process such as retort sterilization performed after filling and sealing, there is a problem that the adhesion of the ink is lowered by the heat applied at that time, and there is still room for improvement in these respects .

  The present invention has been made paying attention to the above technical problem, and uses ultraviolet curable ink to produce a printing film that is attached to a can body by an ink jet printing method that does not require plate making. Reduces time-setting work, improves printing efficiency and reduces product costs in response to a wide variety of products and small lots, and even when retorted and heated An object of the present invention is to provide a method for producing a printed film sticking can body in which the adhesion of ink does not decrease.

  In order to achieve the above object, according to the invention of claim 1, after forming a cylindrical can body from a metal plate, a thermoplastic resin film having a printed layer is bonded to the heated can body portion of the cylindrical can body. In the manufacturing method of a printing film sticking can body which manufactures a film sticking can body by heat-bonding via an agent layer, the other side of the thermoplastic resin film in which a clear coat layer is formed on one side In addition, a base treatment process for improving the adhesion to the printed layer is performed to form a base layer, and an ultraviolet curable ink is ejected from the ink jet printer onto the other surface on which the base treatment is performed. A printing layer in which a temporarily cured printing layer is formed, the adhesive is applied thereon, and the adhesive is heated and dried to form a printing film; and a glass transition point of the printing film. A film adhering step for adhering the adhesive layer relative to the can body portion of the cylindrical can body heated to a temperature range below the melting point, and the printed film is attached to the can body portion After that, the method includes an ultraviolet irradiation step of irradiating the printing film with ultraviolet rays to fully cure the ultraviolet curable ink.

  The invention according to claim 2 is the invention according to claim 1, wherein the base treatment step is performed by coating the other surface of the thermoplastic resin film with a coating material made of an ultraviolet curable resin. The method characterized by forming.

  Further, the invention of claim 3 is the invention of claim 1, wherein after the printing film is attached to the can body, the inner surface of the cylindrical can body is coated while rotating the cylindrical can body, It is a method characterized by further comprising an inner surface coating step of drying the coating surface by heating and completely curing the adhesive.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the rib portion at the bottom of the cylindrical can body is coated with a thermosetting paint between the film attaching step and the inner surface coating step. The method further comprises a coating heating step of forming a lubricant-containing protective coating layer by drying by heating and curing.

  According to the first aspect of the present invention, the ultraviolet ray curable ink is ejected and adhered by the inkjet printer to the thermoplastic resin film subjected to the base treatment for improving the adhesion with the printing layer, thereby forming the printing layer. As a result, a printing film to be attached to the can body is printed. Then, the printing film is thermally bonded to the can body portion of the metal cylindrical can body via an adhesive, and then the ultraviolet light is irradiated to the printing film adhered to the can body portion, and the ultraviolet curable type The ink is fully cured, that is, completely cured, and a printed film sticking can body is manufactured. Therefore, it is not necessary to use an original plate for printing, and it is possible to reduce plate making costs, reduce setup change work at the time of printing, and reduce manufacturing costs. In addition, the lead time of the printing process can be shortened, and a printed film sticking can body can be manufactured in conformity with a wide variety of products and small lots. Furthermore, after the printing film on which the temporarily cured printing layer is formed is attached to the can body, the ink is completely cured by irradiation with ultraviolet rays, so that the ink is prevented from cracking and the ink on the film Thus, it is possible to attach a printing film in a state where the printing quality is stabilized, and it is possible to obtain a printing film adhesion can body that prevents a decrease in the adhesion of ink in the retort heat treatment.

  In addition, according to the invention of claim 2, by applying an ultraviolet curable resin as the base treatment, when the coating layer is dried and cured, the thermal effect of the film is reduced and the film becomes brittle. And the adhesion of the ultraviolet curable ink to the film can be improved. As a result, a printed film having a stable film size after printing can be obtained. Further, when post-processing such as neck molding, flange molding, and screw molding is performed, it is possible to prevent the printed film from peeling from the can body. Furthermore, when the printing film is attached to a two-piece can, the adhesion between the printing film and the can body can be improved, so that the can body is spun when coating the inner surface of the can body of the two-piece can. By doing so, it is possible to prevent the adhered printed film from being peeled off from the can body.

  Furthermore, according to the invention of claim 3, for example, a seamless can such as a drawn can, a thinned deep drawn can (stretch can), a squeezed iron can (DI can), a bottle-type can, etc. For the inner surface coated can that requires painting on the peripheral surface, the inner surface coating is applied after the printing film is adhered to the can body, and the coating film is heated and dried. And when the adhesive used for sticking of the said printing film consists of a thermosetting resin by the heating, the adhesive is hardened completely. Therefore, the adhesiveness of a printing film improves and the printing film sticking can body with which printing quality was stabilized can be obtained.

  According to the fourth aspect of the present invention, the lubricant-containing protective coating layer can be formed on the can bottom including the rib portion of the can body before the inner surface coating step. Therefore, in the subsequent inner surface coating process, even when the can body is spun when the inner surface of the can body is coated, peeling of the printed film can be prevented. In addition, by covering the rib part with a protective coating film containing a lubricant, for example, in the post-process such as a can manufacturing process or a filling process, the slipperiness of the can can be improved, Faster movement is possible and productivity can be improved.

  Next, the present invention will be described more specifically. A can body 1 as an object of the present invention shown in FIG. 1 is made of metal, and a metal plate as a material thereof is a surface-treated steel plate such as an aluminum plate, an aluminum alloy plate, tin-free steel, tinplate, or a chrome-plated steel plate. Aluminum plated steel plates, nickel plated steel plates, and other various alloy plated steel plates can be used. Moreover, the raw material which coat | covered the surface which should become the can inner surface side of a metal plate with an orientation thermoplastic resin can also be used. The can body 1 is a three-piece can composed of a can body and a canopy and a bottom lid, or a can bottom and a can body such as a drawn can, a redrawn can, a stretch can, a squeezed iron can, and an impact can. Seamless cans, ie two-piece cans. Normally, neck-in processing and flange processing are performed on the opening end portion of the can body to form the neck-in portion 1a and the flange portion 1b, and finally the canopy is wound up.

  In addition to the three-piece can and the two-piece can as described above, the can body 1 is a reseal can or bottle type in which a threaded portion is formed at the neck-opened opening end and the cap is wound around the threaded portion. The top dome is molded on the bottom of the can or seamless can body, the mouth and neck and shoulders are formed, the cap is tightened on the screw formed on the mouth and neck, and the opening at the bottom of the can body Neck-in processing and flange processing are applied to the bottle, and another bottle-type can in which the bottom lid is wound is also possible.

  Specifically, the thermoplastic resin film 2 attached to the can is a copolymer made of a polyester resin such as polyethylene terephthalate resin or polybutylene terephthalate resin, a copolymer of polyethylene terephthalate and isophthalic acid, or the like. A thermoplastic resin composed of a single transparent polymer resin selected from polyester resins, polypropylene resins, polycarbonate resins, polystyrene resins, polyolefin resins, vinyl chloride resins, polyvinylidene chloride copolymers, etc., or a composite of the above resins. A resin film is used. Among these, a polyethylene terephthalate resin film that extends to some extent in the circumferential direction of the can 1 at a linear pressure of 147 to 588 N / cm (15 to 60 kgf / cm) and that has heat resistance is used in the attaching step. preferable. The thickness of the resin film can be determined as appropriate. For example, a resin film having a thickness of about 10 to 30 μm can be used.

  A clear coat layer can be formed in advance on one surface of the thermoplastic resin film 2. As the clear coat, specifically, a polyester resin, an epoxy resin, an epoxy-modified polyester resin, an acrylic resin, etc., which uses a curing agent such as an amino resin, and contains a known lubricant as a coating material. It can be illustrated. For example, the polyester resin preferably contains organic or inorganic fine particles as a lubricant as necessary in order to improve film winding property during film formation, film transportability, and the like. Examples of such fine particles include calcium carbonate, calcium oxide, aluminum oxide, kaolin, silicon oxide, zinc oxide, crosslinked acrylic resin particles, crosslinked polystyrene resin particles, urea resin particles, melamine resin particles, and crosslinked silicone resin particles. In addition to fine particles, other resins such as colorants, antistatic agents, antioxidants, lubricants, catalysts, polyethylene, polypropylene, ethylene-propylene-polymers, and olefinic ionomers are optional as long as the transparency is not impaired. Can be contained.

  FIG. 2 schematically shows a process of coating the thermoplastic resin film 2 with a clear coat. When the film 2 fed from the feed roll 3 passes through the gravure roll coater 4, one of the films 2 is here. The surface is continuously or spot-coated with clear paint, then passes through the dryer 5, and after the clear coat is dried, it is wound on a winding roll 6. In addition, since the spot coat in which the clear paint is spot-coated is performed for each length of one can on the long film, the clear coat layer has a length corresponding to one round of the can body as one unit. Although repeated, it is preferable to select a continuous coat on which the clear paint is continuously coated from the viewpoint of paintability. Moreover, as the dryer 5, a warm air dryer, a hot air dryer, an infrared dryer which heats by irradiating infrared rays, etc. can be used. In addition, the adhesion amount of a clear coat shall be the quantity from which the thickness will be 0.5-3 micrometers, for example. Further, the method for performing the clear coating is not limited to the gravure roll coater, and the coating may be performed by a known method such as a roll coater or a die coater.

  When printing is performed on the thermoplastic resin film 2 using inkjet, the ink used for inkjet is generally water-based ink, oil ink, ultraviolet curable ink or the like in which a dye is dissolved as a coloring material in an aqueous solvent. However, unlike printing on paper, UV curable ink is used for printing on a medium having no ink absorption, especially on a synthetic resin film, because ink absorption cannot be expected. In addition, ultraviolet curable ink for ink jet printing has a low viscosity, is difficult to vaporize, and has excellent physical properties that are difficult to scatter. In order to reduce the viscosity of the ink and increase its fluidity, a photopolymerizable monomer can be used as a reactive diluent, or an organic solvent that dissolves an ultraviolet curing component can be added. The curable ink is preferably solvent-free because it is temporarily cured immediately after ink landing at the time of ink jetting and is finally cured after the printing film is attached to the can body. That is, if the solvent remains in the cured image, there may be a problem of deterioration in solvent resistance and a problem of the remaining solvent volatile organic compound (VOC). Therefore, it is preferable in view of dispersibility that the dispersion medium is not a solvent but a polymerizable compound, and among them, a monomer having the lowest viscosity is selected.

  For UV curable inks, radical polymerization type and cation polymerization type are known, but cation polymerization type ink has no cure shrinkage, no odor, no influence of polymerization inhibition by oxygen, etc. For reasons, it is suitable for beverage cans.

  The cationic polymerization ink contains at least a cationic polymerizable substance such as epoxy, oxetane, and vinyl ether, a photopolymerization initiator, and a coloring material, and is cured with ultraviolet rays and fixed on the film. In contrast to general coating and printing, the image forming method using ink jet is preferably a low-viscosity microdroplet in order to obtain a high-definition image.

  The viscosity of the ultraviolet curable ink is 30 mPa · s or less, preferably 20 mPa · s or less at 25 ° C. Further, the ultraviolet curable ink is configured to have an ideal ratio from the viewpoint of the pigment to resin binder ratio. Examples of the resin binder for this purpose include epoxy acrylate resins, polyester acrylate resins, polyurethane acrylate resins, polyether acrylate resins, polybutadiene acrylate resins, and the like, as long as they exhibit a polymerization reaction with ultraviolet rays. In addition, said ultraviolet curable resin can also be used as a single-piece | unit or 2 or more types of mixtures.

  Specific examples of the reactive diluent based on the photopolymerizable monomer include: a monofunctional monomer; a bifunctional monomer such as 2-hydroxyethyl acrylate and tetrahydrofurfryl acrylate; a dicyclobenthenyl acrylate, a dicyclobenzenialoxyethyl acrylate, Tri- or higher functional monomers such as 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, diethylene glycol, neoventyl glycol diacrylate, tripropene glycol diacrylate; Examples include methylolpropane triacrylate, bentaerythritol triacrylate, and dipentaerythritol hexaacrylate.

  It is preferable to mix a photopolymerization initiator in the ink composition. Specific examples of the photopolymerization initiator include acetophenone, benzophenone, Michler ketone, benzyl, benzoin, benzoyl isobutyl ether, benzine methyl ketal, tetramethyl thiuram sulfide, azo hisisobutyronitrile, benzoyl peroxide, di-tert-butyl peroxide. 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 2 -Chlorothioxanthone, methylbenzoyl formate and the like. These photopolymerization initiators may be used alone or in combination of two or more.

  Ink is printed using four colors of cyan (C), yellow (Y), magenta (M), and black (K), or magenta light color (LM) and cyan light color on CMYK. Six-color printing with (LC) added may be used. Further, six-color printing in which orange and green inks are added to CMYK may be used. The pigment dispersion is preferably such that the average particle diameter of the pigment particles is 0.08 to 0.5 μm <, so that the maximum particle diameter is 0.3 to 10 μm, preferably 0.3 to 3 μm. Selection of a pigment, a dispersant, a dispersion medium, dispersion conditions, filtration conditions, and the like are appropriately set. By such particle size control, clogging of the head nozzle can be suppressed, and ink storage stability, ink transparency, and curing sensitivity can be maintained.

  Various additives other than those described above can be used for the ultraviolet curable ink according to the present invention. For example, surfactants, leveling additives, matting agents, polyester resins for adjusting film properties, polyurethane resins, vinyl resins, acrylic resins, rubber resins, waxes, and the like can be added.

  In terms of ejection stability, the UV curable ink is ejected by heating and heating the head and the ink to 35 to 100 ° C., preferably 40 to 80 ° C. to improve the fluidity of the ink. preferable. UV curable ink has a large viscosity fluctuation range due to temperature fluctuations, and the viscosity fluctuation directly affects the droplet size and droplet jetting speed and causes image quality degradation. Therefore, it is as constant as possible while raising the temperature of the UV curable ink. It is necessary to keep on. The control range of the ink temperature is set temperature ± 5 ° C., preferably set temperature ± 2 ° C., more preferably set temperature ± 1 ° C.

  Further, the irradiation of ultraviolet rays is divided into two stages, that is, after the ultraviolet curable ink is first landed, the ultraviolet rays are irradiated and temporarily cured by the method described above, and after the film sticking described later is completed, the ultraviolet rays are further irradiated. Irradiating and curing the resin, it is possible to suppress shrinkage of the thermoplastic resin film that occurs when the ink is cured.

  The curing time of the UV curable ink depends on the thickness of the printing film, the UV source, the photopolymerization initiator, the reactive diluent, the distance between the UV source and the coating surface to be cured, the desired curing condition, etc. Although it is different, the time is appropriately determined in the range of 0.001 seconds to 2.0 seconds. Adjust the curing time of the UV curable ink so that the followability of the ink and the printed appearance are good when performing post-processing such as necking and screw forming after the printing film is attached to the can. The landed ink is temporarily cured to be tack-free, that is, the surface of the ink is cured by about 80%, the surface is not sticky, and the middle part of the ink is made smaller than the surface curing rate. Manufacturing efficiency can also be improved by setting it as the hardening state of about%.

  In addition, as a head used for printing, a continuous discharge method and a DOD (drop on demand) method are known, but the DOD type is more widely used. Among the DOD types, two types, a thermal method and a piezo (piezoelectric) method, are known. Commercially, a piezo head that pressurizes ink and changes the volume of a pressure chamber for ejecting from a nozzle is used. Piezo method is desirable.

  From the viewpoint of printability and workability, or transferability of printing that is likely to occur when the printed film 2 is wound and stored, the surface on which the printing of the film 2 is performed is subjected to a ground treatment, Patterns and characters are formed on the surface by ink jet printing. As the surface oxidation treatment of the surface to be subjected to such printing, there are treatment methods such as corona discharge treatment, flame treatment, plasma treatment, glow discharge treatment, ozone treatment, etc., preferably on the film surface by corona treatment, flame treatment. Oxidation treatment is performed.

  Further, after such an oxidation treatment, a base coating (anchor coating) is further applied to the surface to improve the adhesion to ink. As the surface modifier at that time, those selected mainly from a primer and an antistatic polymer can be used as a single substance or as a mixture of two or more kinds. For example, from the viewpoint of improving printability, a primer is preferable as the above surface modifier, and when it is necessary to impart antistatic properties, a primer and an antistatic polymer can be used in combination.

  As the primer, polyethyleneimine, ethyleneimine / ethyleneurea copolymer or the like is used as an anchor coating agent. Among these, in order to improve the adhesion with the ultraviolet curable ink landed by the ink jet method, and to prevent the landed ink dots from becoming large and to prevent ink bleeding, An easy adhesion primer obtained by blending a cured polyester resin and an ultraviolet curable resin or a primer made of a porous material is used. For example, an aqueous primer solution of an alkyl-modified ethyleneimine polymer is applied on the resin film 2. It is preferable to dry and form a film layer. Examples of the halide used as the modifier include methyl chloride, ethyl bromide, n-butyl chloride, lauryl chloride, stearyl iodide, oleyl chloride, cyclohexyl chloride, benzyl chloride and the like. Further, by adding porous silica to the resin used for the primer, it is possible to prevent ink jet ink from bleeding. That is, the ink can enter a small depression or hole on the silica surface and prevent bleeding. A thermosetting resin such as an acrylic resin or an epoxy resin is used for this primer, and silica having a particle size of about 0.3 μm to 5 μm, preferably about 0.8 μm to 3 μm is added to the resin. The amount to be added is preferably about 0.1% to 2%, and if it exceeds 2%, the primer coating is applied to the film, the transparency of the film is lowered, which is not preferable in terms of printed appearance. On the other hand, if it is less than 0.1%, the effect of preventing ink bleeding is weak.

  The coating agent comprising the resin composition as described above is applied on a film and then dried to form a base film (underlayer) on the film. The anchor coating agent is a silk screen printing method or gravure printing method. However, as other coating methods, a normal coating method using a roll coater, a reverse coater, a die coater, a spray coater, or the like is also employed.

  After ink jet printing, colored inks that have landed on each other can be applied to the can 1 after being dried and cured by irradiating with ultraviolet rays from an ultraviolet lamp. If the film is completely cured, stress cracks are likely to occur in the ink due to changes in the pressure and shape when the film is adhered to the can 1, and the cracks are caused by the molding force during post-processing. There is a problem in that it promotes adhesion defects and deteriorates workability. Therefore, a printed layer is formed on the landed ink in an uncured or incompletely cured temporarily cured state. A conventionally known thermosetting adhesive, electron beam curable adhesive, or ultraviolet curable adhesive, which is easily adhered by heating and pressing, is applied onto the temporarily cured printing layer. .

Specific examples of the thermosetting adhesive include polyester resin, epoxy resin, polyurethane resin and the like containing a curing agent such as amino resin and isocyanate resin, and have a melting point of 140 to 160 ° C. and a softening point of 60. The thing of -70 degreeC can be illustrated. As the adhesion method, it is preferable to employ a spray method because the landed ink is in a temporarily cured state. The coating amount at that time is preferably 70 to 130 mg / dm ² . As the electron beam curable adhesive, one prepared by mixing a resin component composed of a polyester resin and an oligomer, a stress relaxation agent and, if necessary, a color pigment, and diluting with an organic solvent or the like is used. The UV curable adhesive basically consists of three components: photopolymerizable prepolymer, photopolymerizable monomer, and photoinitiator. Sensitizer, solvent, leveling agent, tackifier, polymerization Inhibitors, stabilizers, etc. are added.

  Further, an electron beam curable adhesive or an ultraviolet curable resin can be blended with the thermosetting adhesive, and in this case, an epoxy resin, an amino resin, or the like is used. The blending ratio with the thermosetting adhesive can be appropriately set depending on the ultraviolet curable ink and the use conditions such as the electron beam or ultraviolet irradiation conditions of the curing device for curing the adhesive and the environmental atmosphere.

(Manufacturing process)
FIG. 3 schematically shows a production process of a printed film sticking can body according to the present invention, and the thermoplastic resin film 2 coated with the clear coat on one side is fed out from an unwinding roll (process P0 to P3). The surface of the film 2 on which the clear coat is not applied is subjected to a ground treatment described later (processes P4 to P6), and yellow (Y) and magenta (M) are applied to the ground-treated surface from the inkjet printer head. Each ultraviolet curable ink such as cyan (C) and black (B) is landed (process P7).

  After a printed layer such as a pattern is formed by an ink jet method using the above ink, ultraviolet rays are irradiated using an ultraviolet irradiation device, and the composition in the ink is temporarily cured (process P8). The curing light source may be a general ultraviolet curing light source (wavelength: 300 to 450 nm), although it depends on the absorption wavelength of the photopolymerization initiator used.

  The ink printed in the polymer is taken in and fixed by temporary curing of the composition uniformly dispersed in the ink layer. Further, the ink layer itself is a tough flexible film.

  On the surface of the film 2 on which printing is to be performed, an anchor coating (primary surface treatment) having both thermosetting and ultraviolet curing properties as a pretreatment to prevent bleeding of the landed ink and to improve adhesion. Is applied to form a so-called base layer (base processing step; processes P4 and P5). Then, after inkjet printing with ultraviolet curable ink, ultraviolet rays are irradiated, the surface of the ink loses tackiness, and a printing layer is formed in a temporarily cured state where the ink is incompletely cured. At this time, a clear coat layer is formed on the upper surface of the film 2, and an adhesive is applied to the other surface (the surface on which the printing layer is formed) of the film 2 on the opposite side, and heating is performed. It is dried (printing process; processes P7 to P10). And it is wound up by a roll etc. once as a printing film stuck on the can 1 (process P11).

  Next, the printing film 2 is conveyed by a feed device (not shown), and is cut for each length corresponding to one round of the can body, so that the printing film 2 reaches a predetermined temperature within the temperature range above the glass transition point and below the melting point. It sticks to the heated can 1 (film sticking process; process P13).

  When the printing film is attached to the can 1, the surface of the can body to which the printing film is attached is again irradiated with ultraviolet rays, and the UV curable ink that has been in a temporarily cured state is fully cured, that is, completely cured. (Ultraviolet irradiation process; process P14).

  When the can body 1 is a seamless can such as a two-piece can or a bottle-type can, for example, the rib portion on the bottom of the can body 1 is coated with a thermosetting paint, and then heated in an oven. As a result, a lubricant-containing protective coating layer is formed on the rib portion (coating heating step; processes P15 and P16).

  Then, the inner surface of the can body 1 is coated with a predetermined paint and heated and dried (inner surface coating process; processes P17 and P18). At this time, the adhesive made of a thermosetting resin used when the above-described printing film is attached to the can 1 is also heat-dried to enhance the adhesion between the printing film and the can 1. . Thereafter, subsequent processes such as neck machining are sequentially performed (process P19).

  FIG. 4 schematically shows a cross section of the printed film and the can 1 to which the printed film is attached at the stage where the above steps are completed. First, an anchor-coated base layer 11 is formed, and a printing layer 12 that is inkjet-printed with ultraviolet curable ink is formed on the lower surface of the base layer 11. And the adhesive layer 13 is formed in the lower surface of the printing layer 12, and the printing film and the can 1 are adhere | attached through the adhesive layer 13. FIG. A clear coat layer 14 is formed on the upper surface of the film 2 in FIG.

(Manufacturing equipment)
FIG. 5 schematically shows an outline of a production apparatus for a printed film-attached can body according to the present invention, and a cutter roll 21 that sandwiches the above-described printed film and cuts it for each length corresponding to one round of the can body. And the fixed blade 22 are arranged close to the sticking roll 23. This cutter roll 21 is provided with a cutter that cuts a long film into a length corresponding to one round of the can body every rotation, and the long film runs so as to cut at the connecting portion of the printing screen. It is comprised so that it may rotate in synchronization with.

  The adhering roll 23 is a roll having a circumferential length equivalent to a plurality of cans, and adsorbs a plurality of printed films cut to a length corresponding to one round of the can body at predetermined intervals on the outer circumferential surface. To hold. The sticking roll 23 is disposed at a predetermined location close to a turning circle of a plurality of mandrels 24 that are fitted with the can body 1 and turn and move. A supply station 25 is provided on the so-called upstream side in the turning direction of the mandrel 24 in the turning circle, and a supply conveyor 26 is arranged toward the supply station 25. The supply conveyor 26 conveys the cans 1 formed by drawing or drawing ironing using a metal plate such as an aluminum plate in a line, and the mandrel of the supply station 25 at the most advanced portion. The can body 1 is delivered to 24 and fitted therein.

  An induction heating device 27a that heats the surface of the mandrel 24 between the upstream side and the downstream side in the swirling direction of the mandrel 24 with respect to the supply station 25 and the above-described sticking roll 23, and a mandrel 24 An induction heating device 27b that heats the can body 1 fitted in is disposed. The induction heating devices 27a and 27b heat the temperature of the can body 1 and the mandrel 24 so that the temperature is sufficient for the heat bonding of the film 2. The heating can be performed by heating only the induction heating device 27b. Although it is possible to set temperature to 150-170 degreeC, for example, in order to make heating temperature rise of the can 1 uniform, it supplies after heating the can 1 before being fitted to the mandrel 24 It is preferable to use both heating devices, and it is preferable to advance the curing reaction of the adhesive in this sticking step in order to minimize the thermal history of the film 2.

  Of the swirl circle of the mandrel 24, the point close to the adhering roll 23 is the bonding station 28, and the cut film 2 can be separated with the adhesive layer facing outward, that is, the adhesive layer can be bonded at the bonding station 28. Adsorbed and held on the sticking roll 23 in a direction opposite to the body 1. A film having a length of one can that is adsorbed and held on the sticking roll 23 is pressed against the can 1 that has been heated and heated, thereby being wound around the can 1. Further, the holding force at that time is set to, for example, 294 N / cm (30 kgf / cm) as a linear pressure.

  A pressing station 29 is provided continuously to the bonding station 28, and a pressing roll 30 is disposed in the pressing station 29. The pressing roll 30 is rotated to come into contact with the can body 1 to press the film 2 adhered to the surface of the can body 1 to increase the adhesiveness of the adhesive. By adjusting the distance from the mandrel, for example, it is set to 392 to 588 N / cm (40 to 60 kgf / cm). The film 2 cut to a length corresponding to one round of the can body is bonded to the can body 1 with both end portions of the film 2 being overlapped.

  Further, an ultraviolet irradiation device 31 is disposed on the downstream side in the turning direction of the mandrel 24 with respect to the pressing station 29, and is adhered to the can 1 at the bonding station 28 and the pressing station 29, The pressed printing film is irradiated with ultraviolet rays, and the ultraviolet curable ink is fully cured, that is, completely cured.

  And the carrying-out station 32 is provided in the downstream in the turning direction of the mandrel 24 with respect to said ultraviolet irradiation device 31, and the can 1 to which the printing film was stuck and the ultraviolet-ray was irradiated is this carrying out. It is sent out from the station 32 toward the carry-out conveyor 33. The carry-out conveyor 33 is a conveyor for transporting the can body 1 with the film 2 attached thereto to a subsequent process such as neck-in processing, flange processing, or can lid winding processing.

  In the above specific example, the process from the unwinding of the film 2 to the printing and winding up is separated from the process of pasting the printing film. It is also possible to manufacture a printed film sticking can body by a process in which printing and sticking are consistent.

  Furthermore, in the above specific example, the uncoated film 2 is subjected to a clear coat (process P0 to P2), and then subjected to a base treatment (process P4, P5), but the order of these steps is reversed. It is also possible to produce a printed film sticking can.

  And in said specific example, although the example for two-piece cans is described as film sticking can body 1, this invention is not limited to this, Three-piece cans, such as a welding can, a bottle type can, etc. It can also be applied to. In addition, in a film laminate can formed from a resin-coated laminate plate that does not require inner surface coating, the inner surface coating step can be omitted and the present invention can be similarly applied to other steps. Furthermore, both ends of the film 2 when the printing film is wound around the can body may be in a state of being overlapped with each other or a state of being abutted with each other. In addition, in the case of a laminated can molded with a resin-coated film laminated plate, or a two-piece can molded with a metal plate coated with a thermosetting coating film such as polyester resin, or a bottle-shaped can, the can It is also possible to omit painting of the bottom rib.

  Moreover, although the main curing process of the ultraviolet curable ink of the printing film adhered to the can body 1 is provided before the post-processing process such as neck-in processing, the inner surface coating of the can body 1 is performed after the film is adhered. If it is an inner surface resin-coated can body that does not require, a main curing step of irradiating with ultraviolet rays after the post-processing step may be provided. By doing so, the followability of the printed layer is improved, and the adhesion can be further improved.

(Example)
Next, examples of the present invention will be described. The surface of a polyethylene terephthalate (PET) resin film having a thickness of 16 μm was subjected to a base treatment (an easy-adhesion primer obtained by blending a thermosetting polyester resin and an ultraviolet curable resin, blending ratio = 2: 8). A clear coat made of a polyester resin was spot-coated on one surface of the long film. (Applied at a rate of 10 mg / dm ² )

  The above-mentioned surface treatment coating material (adhesive primer) and clear film layer are dried and cured on the surface of the long surface, that is, on the surface that is not clear-coated, in four colors of yellow, magenta, cyan, and black. On the upper layer of the printed layer, the ultraviolet curable ink is landed using an inkjet method to form a printed image, and further, the printed image is irradiated with ultraviolet rays to be temporarily cured to an incomplete state with a curing rate of 30 to 80%. A thermosetting adhesive (polyurethane resin) containing white pigment (titanium oxide) was applied by spraying. The color ink has an ultraviolet curable resin as a main component, and the composition was such that a pigment part by weight (5) was mixed with a binder part by weight (95).

The melting point of each ink was 100 ° C. (softening point was 60 ° C.), the color ink was deposited to a thickness of 1.0 μm, and the upper layer adhesive was deposited to a thickness of 110 mg / dm ² . The curing time by ultraviolet irradiation for temporarily curing these color inks and adhesives was 0.5 seconds.

  A steel DI can molded into a cylindrical shape from a steel metal plate is heated to 150 ° C. by induction heating, and the printed film is wrapped around the can through an adhesive to slightly overlap both ends of the film. Pasted. The pressing load at the pressing station at this time was a linear pressure of 392 to 588 N / cm (40 to 60 kgf / cm).

  Then, in the ultraviolet irradiation station, ultraviolet rays were irradiated from the outer surface side of the film sticking can body, and the base treatment coating material and the ultraviolet curable color ink were fully cured.

  Next, at the paint heating station, the rib part on the bottom of the can is coated with a thermosetting paint containing lubricant, dried and cured, and then the inside of the can is applied while rotating the can body and heated. Dried.

  And when visually observing the obtained film sticking can body, the peeling of the film accompanying the rotation of the can body is not seen, and the influence of bleeding and dot gain of the color image is within a practically negligible range, No abnormalities were observed in the patterns and letters, and a beautiful high-quality printed image with high whiteness was obtained.

  In addition, when the neck-in process and the flange process were performed, no wrinkling or peeling of the film occurred. Furthermore, in order to sterilize the contents of the can body, a sterilization process such as a retort sterilization treatment performed after filling and sealing the contents of the can body was performed, but there was no problem in film adhesion.

It is a side view which shows an example of the can object made into object by this invention. It is a schematic diagram for demonstrating the application | coating process of a clear coat. It is a schematic diagram which shows the manufacturing process of the printing film sticking can body in the method of this invention. It is a schematic diagram which shows the cross section of a printing film and a can body of the stage which completed each manufacturing process of the printing film sticking can body in the method of this invention. It is a schematic diagram which shows the manufacturing process of the printing film sticking can body in the method of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Can body, 2 ... Film, 11 ... Underlayer (anchor coat layer), 12 ... Printing layer, 13 ... Adhesive layer, 14 ... Clear coat layer, 27 ... Induction heating apparatus, 28 ... Bonding station, 29 ... Press Station, 31 ... UV irradiation device.

Claims (4)

After forming a cylindrical can body from a metal plate, a film-bonded can body is obtained by thermally bonding a thermoplastic resin film having a printed layer to a heated can body portion of the cylindrical can body via an adhesive layer. In the manufacturing method of the printed film sticking can body to be manufactured,
A base treatment step for forming a base layer by applying a base treatment for improving adhesion to the print layer on the other surface of the thermoplastic resin film on which a clear coat layer is formed on one side;
A UV-curable ink is ejected from an ink jet printer and adhered to the other surface on which the base treatment has been performed to form a temporarily cured printing layer, on which the adhesive is applied, and the adhesive is applied. A printing process in which the film is heated and dried to form a printing film;
More than the glass transition point of the printing film, a film sticking step of sticking the adhesive layer relative to the can body portion of the cylindrical can heated to a temperature range below the melting point,
After the printing film is stuck to the can body, the printing film is characterized by having an ultraviolet irradiation step of irradiating the printing film with ultraviolet rays to fully cure the ultraviolet curable ink. Method for producing a canned body.   2. The printing film according to claim 1, wherein in the base treatment step, the base layer is formed by coating the other surface of the thermoplastic resin film with a coating material made of an ultraviolet curable resin. Manufacturing method of sticking can body.   After the printing film is attached to the can body part, the inner surface of the cylindrical can body is coated while rotating the cylindrical can body, the coating film is heated and dried, and the inner surface of the adhesive is completely cured. The method for producing a printed film sticking can according to claim 1, further comprising a painting step.   Between the film adhering step and the inner surface coating step, the rib portion at the bottom of the cylindrical can body is coated with a thermosetting paint, dried by heating and cured, and a protective coating film containing a lubricant The manufacturing method of the printing film sticking can body of Claim 3 which has further the coating heating process which forms a layer.

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