Ink jet printing on a metal can substrate

Abstract

A method for forming a beverage can end (34a) having ink jet markings (50a) on its tab (36a) comprises a step of applying ink via an ink jet to a surface of tab stock, wherein the tab stock surface is unlubricated and substantially free of factory lubricant. The method further includes a step of lubricating the tab stock after the step of applying ink, a step of forming the tab stock into tabs, and a step of combining the tabs with an end shell to from the beverage can end.

Claims

1. A method for forming a beverage can end having ink jet markings on its tab, comprising the steps of: treating a tab stock with a solvent to remove factory lubricant; after the step of treating the tab stock, feeding the tab stock into a printing station without coiling the tab stock; at the printing station applying ink via an ink jet to a surface of the tab stock, the tab stock surface being unlubricated and substantially free of factory lubricant; after the step of applying ink, feeding the tab stock via a lubrication station directly into a tab press without coiling the tab stock, where the printing station, the lubrication station, and the tab press belong to a system; forming the tab stock into tabs in the tab press; and combining the tabs with an end shell to form the beverage can end.

2. The method of claim 1 further comprising a step of uncoiling the tab stock, wherein the applying step is performed after the uncoiling step.

3. The method of claim 1 wherein the applying step is performed on an underside of the tab stock.

4. The method of claim 1 wherein the applying step is performed on top side of the tab stock.

5. The method of claim 1 wherein the applying step includes applying indicia to the tab stock.

6. The method of claim 1 wherein the factory lubricant is DOS and the solvent is configured to remove DOS from the tab stock surface.

7. The method of claim 6 wherein, before the applying step, the tab stock has a surface energy of between 36 dyn/cm and 44 dyn/cm on a surface tension test.

8. The method of claim 6 wherein, before the applying step, the tab stock has a surface energy of less than 42 dyn/cm on a surface tension test.

9. The method of claim 6 wherein, before the applying step, the tab stock has a surface energy of less than 40 dyn/cm on a surface tension test.

10. The method of claim 6 wherein, before the applying step, the tab stock has a surface energy of less than 38 dyn/cm on a surface tension test.

11. The method step of claim 1 further comprising steps of receiving the tab stock; and cleaning factory lubricant from the tab stock.

12. The method step of claim 1 further comprising a step of increasing the surface energy of the tab stock.

13. The method of claim 1, wherein the factory lubricant includes DOS, and wherein the tab stock is suitable for being formed into beverage or food can tabs.

14. The method of claim 1, wherein the method for forming the beverage can end is performed at line speeds of over 400 strokes per minute.

15. The method of claim 14, wherein the tab stock includes at least a two tab width stock.

16. The method of claim 2, wherein the treating step is performed after the uncoiling step.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 is a schematic view of a system illustrating aspects of the present invention;

(2) FIG. 2 is a perspective view of beverage can illustrating a first tab embodiment;

(3) FIG. 3 is a perspective view of beverage can illustrating a second tab embodiment; and

(4) FIG. 4 is a perspective view of beverage can illustrating a first tab embodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(5) A system and methods for ink jet printing are described for aluminum beverage can tab stock. As shown in FIG. 1, a system 10 for forming a beverage can tabs include a coil 12 of aluminum tab stock, a dereeler 14, an isolation mechanism 16, an ink jet printing station 18, a lubrication station 20, and a tab press 22. Dereeler 14 and isolation roller system 16 preferably are conventional.

(6) Ink jet printing station 18 preferably employs conventional ink jet printing technology using an ink that is compatible with the materials and coating common to the beverage can industry. Lubrication system 20 preferably is conventional. Tab press 22 forms tabs by cutting and bending portions of material strip (not shown in FIG. 1). Press 22, for example, may be a model BSTA-90/20 made by Bruderer of Switzerland or a model PM2-80 made by Minster in the United States.

(7) The coiled tab stock typically has a width for three or four tabs. Tab stock typically is a 5000 series alloy, such as a 5182 alloy having a thickness of 0.0110 inches or less. The tab stock is substantially free of factory lubricant such as DOS such that it has a suitable surface for adherence of coatings from the ink jet printing process. The ink jet printing preferably is applied to the underside of the tab stock (that is, the surface that becomes the underside of the tab upon formation in the tab press). The present invention also encompasses ink jet printing on the top side of the tab stock. High flexibility UV cured inkjet inks are applied during the print process having been fully approved for the intended application.

(8) FIG. 2 illustrates a beverage can 30 including a can body 32 and a can end 34 attached to can body 32 by a double seam. A tab 36 includes an underside 38 and a top side 40 (not shown in FIG. 2). Indicia 50, illustrated by a 2D bar code such as a QR code, is located on tab underside 38. 2D bar code 50 is produced according to the methods described herein. The present invention encompasses other indicia, such as information, promotional, or sweepstakes information without limitation.

(9) FIG. 3 illustrates a beverage can 30a that includes a tab 36a. Indicia 50a, illustrated by a logo, is located on the top side 40a. Logo 50a is produced according to the methods described herein.

(10) FIG. 4 illustrates a beverage can 30b that includes a tab 36b. Indicia 50b, illustrated by a logo, is located on the underside 38b of the tab. Logo 50b is produced according to the methods described herein in a way such that the inkjet printing forms a negative of logo 50b. Logo 50b is formed by ink surrounding visible aluminum.

(11) The tab stock coil 12 may come from the supplier substantially free of factory lubricant, such as DOS, or the tab stock may be treated before the ink jet printing station 18. The coil may be cleaned with a conventional solvent chosen for the particular lubricant. Other conventional means, such as corona treatment, plasma treatment, and flame treatment, may be used to increase the surface energy of the tab stock before it enters the ink jet printing station. After forming the printed tabs, the tabs may go to a conversation press (not shown in the figures) for application to can end shells. Alternatively, the ink jet printing may occur before the tab stock is coiled, such as by the aluminum producer.

(12) At least in circumstances in which the factory lubricant is DOS, it may be an advantage to treat, such as by solvent cleaning or other conventional method, the tab stock to have a surface energy that is less than 44 dyn/cm on a surface tension test, preferably less than 42 dyn/cm, or less than 40 dyn/cm, 38 dyn/cm, or more preferably less than 36 dyn/cm on a surface tension test. There is a lower practical limit for the minimum surface energy that will depend on the particular choice of ink and substrate properties, as will be understood by persons familiar with printing on metal packaging substrates.

(13) According to the present technology, the ink jet process is a single stage process, as distinguished from commercial laser ablation of a colored coating. Further, the ink applied by the present technology typically will be dark on a light aluminum background. Therefore, 2D codes would be printed conventionally as opposed to being inverted as might be contemplated with laser etching. In this regard, a 2D code applied by ink jet printing may be easier to read by smartphones and other wireless communication devices. Also, ink jet printing technology is flexible in that is provides many colors, speed that can match commercial tab stock line speeds of over 400 strokes per minute, preferably over 600 strokes per minute, and more preferably over 700 strokes per minute with a two, three, four, or more tab width stock.

(14) Preferred embodiments and methods have been described herein to illustrate aspects of the present invention. The present invention is not limited to the particular embodiments and methods described herein. Rather, the inventors intend the invention to be given its fully scope as defined in the claims.