EP2851307B1

EP2851307B1 - Method for reducing corrosion in filled and seamed beverage cans

Info

Publication number: EP2851307B1
Application number: EP13185241.0A
Authority: EP
Inventors: Ivan Mijatovic
Original assignee: Rexam Beverage Can Europe Ltd
Current assignee: Ball Beverage Packaging Europe Ltd
Priority date: 2013-09-19
Filing date: 2013-09-19
Publication date: 2016-07-20
Anticipated expiration: 2033-09-19
Also published as: BR112016006166A2; WO2015040017A1; US20160236825A1; ES2592333T3; EP2851307A1

Description

TECHNICAL FIELD

The invention relates to filling and seaming beverage containers; more particularly, the invention relates to reducing corrosion of filled and seamed aluminum beverage cans.

BACKGROUND OF THE INVENTION

Referring to FIG. 1, typical end closures or can ends 10 for beer and beverage containers have an opening panel 20 and an attached leverage tab 26 for pushing the opening panel 20 into the container to open the end. The container is typically a drawn and ironed metal can, usually constructed from a thin plate of aluminum. End closures 10 for such containers are also typically constructed from a cutedge of thin plate of aluminum or steel, formed into a blank end, and manufactured into a finished end by a process often referred to as end conversion. These ends are formed in the process of first forming a cutedge of thin metal, forming a blank end from the cutedge, and converting the blank into an end closure which may be seamed onto a container.
These types of container ends 10 have been used for many years, with almost all such ends in use today being the "ecology" or "stay-on-tab" ("SOT") ends in which the tab 26 remains attached to the end after a tear panel 20, including large-opening ends ("LOE"), is opened. The tear panel 20 being a portion of the can end defined by a frangible score length 22. The tear panel 20 may be opened, that is the score 22 may be severed, and the tear panel 20 displaced at an angular orientation relative to the remaining portion of the can end 10, thus creating a pour opening through which the beverage may be poured from the container. The tear panel 20 remains hingeably connected to the remaining portion of the can end by a hinge segment 25, leaving an opening through which the user draws the contents of the container. In an LOE, the pour opening is about 3.2 square centimeters (0.5 square inches) in area.
Opening of the tear panel 20 is operated by the tab 26 which is attached to the can end 10 by a rivet 34 through a rivet island on the tab 26. The tab 10 is attached to the can end 10 such that a nose 30 of the tab 26 extends over a proximal portion of the tear panel 20. A lift end 32 of the tab 26 is located opposite the tab nose 30 and provides access for a user to lift the lift end 32, such as with the user's finger, to force the nose 30 against the proximal portion of the tear panel 20.
When the tab nose 30 is forced against the tear panel, the frangible score 22 initially ruptures at a vent region of the score. This initial rupture of the score 22 is primarily caused by the lifting force on the tab 26 resulting in lifting of a central region of the can end 10, immediately adjacent the rivet. As the tab 26 is lifted further, the score rupture propagates along the length of the score 22, eventually stopping at the hinge segment 25.
Again, these end closures are typically manufactured from a sheet of a metal substrate, such as aluminum, tin plated steel, or tin free steel. The metal sheet may have a cured protective coating on the opposing upper and lower surfaces. The protective coating protects the exterior of the end closure from corrosion, either during processing or during storage of the packaged product. Any oxidation, corrosion or rust on the surface of the end closure 10 represents an unattractive product appearance to the consumer and is unacceptable to can manufacturers in general.
Forming the frangible score 22 can damage the protective coating. The scoring process requires penetration of a forming tool into a thickness of the coated metal sheet. This penetration moves metal in the sheet to form the frangible score 22 creating a score depth well into the thickness of the coated metal sheet (e.g., about ½ to about ²/₃ of the metal thickness). This often destroys the integrity of the protective coating on the exterior surface, creating a site where corrosion can occur.
Referring to FIG. 2, end closures 10 of this type are attached to an open end 36 of a container body 40 after the container body 40 has been filled with a beverage in a process called double seaming. The seaming process typically requires the container body 40 and the end closure 10 to be elevated and clamped between a base plate and a seaming chuck 44. A first set of seaming rollers 48 is rotated about the seaming chuck 44 along the open end of the container with sufficient pressure to form a first portion of a double joining seam. When the first step in forming the double seam has been completed, the first pair of opposed seaming rollers 48 is retracted, and the seaming rollers of a second pair 52 are actuated to complete the double seam. When the seaming of the end closure 10 to the can body 40 is complete, the second set of seaming rollers 52 is retracted, and a base plate piston is retracted. At the same time, a seamer knockout piston carried centrally of the seaming chuck 44 is actuated striking the exposed outer surface of the end closure 10 to ensure freeing of the sealed container from the chuck 44 to complete the seaming operation. The double seaming process can result in scratches 56 on the exposed outer surface of the end closure 10 (see FIG. 1). Similar to damage inherent with the scoring process, a protective coating applied subsequent to scoring but prior to seaming can be damaged during the double seaming process.
The prior art describes methods of providing a sprayer to repair can ends subsequent to scoring but prior to seaming. However, these solutions do not adequately address providing corrosion resistance for damage occurring to can bodies and can ends subsequent to can end manufacture and/or subsequent to can filling and can end double seaming.
US 6,244,020 describes a process for manufacturing a container and a container which can be readily opened without a tool wherein after sterilization of the sealed container a wall of the container is weakened to permit the top to be twisted off without the use of a tool. WO 2004/013240 describes cans with a body portion and an end portion, wherein at least one of the body and end portions are aluminum and are coated on at least one major surface with a coating composition. Suitable coating compositions described include one or more polyester resins, wherein at least one of the polyester resins has a glass transition temperature less than about 50°C, and wherein the polyester resin is formed by the reaction of one or more polyacid molecules and one or more polyol molecules; and a crosslinker.
The present invention is provided to solve the problems discussed above and other problems, and to provide advantages and aspects not provided by prior end closures of this type. A full discussion of the features and advantages of the present invention is deferred to the following detailed description, which proceeds with reference to the accompanying drawings.

SUMMARY OF THE INVENTION

The present invention is directed to a method for reducing the likelihood of corrosion occurring on a beverage container as set out in the claims. A first aspect of the present invention is directed to a method for reducing the likelihood of corrosion occurring on a beverage container wherein a metallic beverage can body has an end closure attached thereto using, the steps of: (1) filling a beverage can body with a liquid beverage; (2) placing an end closure with a frangible score defined in the end closure to allow opening of the container over an open end of the beverage can body filled with the beverage; attaching the end closure to the beverage can body, for example by: (3) placing a seaming chuck within a perimeter of the end closure; (4) bringing a seaming roller into engagement with a curled outer perimeter of the end closure against a force provided by the seaming chuck; and (5) rotating the seaming roller about the seaming chuck along the open end of the beverage can body with sufficient pressure to form a joining seam. The method is characterized by the further step of rinsing the end closure in a solution comprising a corrosion inhibitor subsequent to attaching the end closure to the beverage can body.
The first aspect of the invention may include one or more of the following features, alone or in any reasonable combination. The beverage can body may be rinsed in the solution subsequent to attaching the end closure to the beverage can body. The end closure may be immersed in a bath of the solution subsequent to attaching the end closure to the beverage can body. The beverage can body may be immersed in a bath of the solution subsequent to attaching the end closure to the beverage can body. The solution may comprise de-ionized water. The solution may be delivered by a sprayer. The solution may react with a bare aluminum oxide layer on the end closure to produce a water resistant layer. The liquid beverage may be pasteurized within the beverage can body wherein the rinsing step is carried out prior to the pasteurizing step. The end closure may be rinsed a second time with a solution comprising a corrosion inhibitor subsequent to the pasteurizing step. The liquid beverage may be pasteurized within the beverage can body wherein the rinsing step is carried out subsequent to the pasteurizing step. The method may be further characterized by the step of forming a water resistant layer on a frangible score on the end closure subsequent to attaching the end closure to the beverage can body. The solution may comprise an acrylic polymer. The acrylic polymer may be a polyacrylate. The solution may comprise 25g/l to 150 g/l of the corrosion inhibitor and 50 g/l to 100 g/l of an acrylic polymer. The solution may comprise 25g/l of a chromium-free corrosion inhibitor and 50 g/l of an acrylic polymer. The corrosion inhibitor may be Deoxylyte®-444.
A second aspect of the present invention is directed to a method for reducing the likelihood of corrosion occurring on a beverage container wherein a metallic beverage can body has an end closure attached thereto using, for example, the steps of: (1) filling a beverage can body with a liquid beverage; (2) placing an end closure with a frangible score defined in the end closure to allow opening of the container over an open end of the beverage can body filled with the beverage; attaching the end closure to the beverage can body, for example by: (3) placing a seaming chuck within a perimeter of the end closure; (4) bringing a seaming roller into engagement with a curled outer perimeter of the end closure against a force provided by the seaming chuck; and (5) rotating the seaming roller about the seaming chuck along the open end of the beverage can body with sufficient pressure to form a joining seam. The method is characterized by the further step of forming a water resistant layer on a frangible score on the end closure subsequent to attaching the end closure to the beverage can body.
The second aspect of the invention may include one or more of the following features, alone or in any reasonable combination. The end closure may be rinsed in a solution comprising a corrosion inhibitor subsequent to attaching the end closure to the beverage can body. The beverage can body may be rinsed in the solution subsequent to attaching the end closure to the beverage can body. The end closure may be immersed in a bath of the solution subsequent to attaching the end closure to the beverage can body. The beverage can body may be immersed in a bath of the solution subsequent to attaching the end closure to the beverage can body. The solution may be delivered by a sprayer. The solution may react with a bare aluminum oxide layer on the end closure to produce a water resistant layer. The liquid beverage may be pasteurized within the beverage can body wherein the rinsing step is carried out prior to the pasteurizing step. The end closure may be rinsed a second time with a solution comprising a corrosion inhibitor subsequent to the pasteurizing step. The liquid beverage may be pasteurized within the beverage can body wherein the rinsing step is carried out subsequent to the pasteurizing step. The solution may comprise an acrylic polymer. The acrylic polymer may be a polyacrylate. The solution may comprise 25g/l to 150 g/l of the corrosion inhibitor and 50 g/l to 100 g/l of an acrylic polymer. The solution may comprise 25g/l of a chromium-free corrosion inhibitor and 50 g/l of an acrylic polymer. The corrosion inhibitor may be Deoxylyte®-444.
A third aspect of the present invention is directed to a method of filling a beverage container with a liquid beverage. The method comprises the steps of: (1) filling a beverage can body with a liquid beverage; (2) placing an end closure with a frangible score defined in the end closure to allow opening of the container over an open end of the beverage can body filled with the beverage; (3) placing a seaming chuck within a perimeter of the end closure; (4) bringing a seaming roller into engagement with a curled outer perimeter of the end closure against a force provided by the seaming chuck; (5) rotating the seaming roller about the seaming chuck along the open end of the beverage can body container with sufficient pressure to form a joining seam whereby attaching the end closure to the beverage can body; (6) rinsing the end closure in a solution comprising a corrosion inhibitor subsequent to attaching the end closure to the beverage can body wherein the solution reacts with a bare aluminum oxide layer on the end closure to produce a water resistant layer.
The method of the invention results in an (optionally) filled beverage container comprising: a metallic beverage can body; an end closure attached to the can body with a frangible score defined in the end closure to allow opening of the container; (optionally a liquid beverage within the can body;) and characterized by at least one of a corrosion inhibitor or a water resistant layer on the frangible score on the end closure. It will be appreciated that a can formed by the method of the invention differs from known containers by the presence of the corrosion inhibitor or a water resistant layer on the frangible score. Optionally wherein, when both are present, the corrosion inhibitor is part of/is held within, the water resistant layer. It will be appreciated also that instead of treating the entire can end it is possible to treat only a discrete area of the can end. For example it is possible to treat only a sufficient area of the can end to ensure the frangible score is treated with corrosion inhibitor or a water resistant layer where the remainder of the can end has been already been treated.
It will be appreciated that the beverage container formed by the method of the invention is of the type described above and as shown in the drawings, for example Figure 1. It will have a tear panel being a portion of the can end defined by a frangible score length. The tear panel may be opened, that is the score may be severed, and the tear panel displaced at an angular orientation relative to the remaining portion of the can end, thus creating a pour opening through which the beverage may be poured from the container. The tear panel remains hingeably connected to the remaining portion of the can end by a hinge segment, leaving an opening through which the user draws the contents of the container. The container of the invention can be formed using the methods of the invention.
Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

To understand the present invention, it will now be described by way of example, with reference to the accompanying drawings in which:

FIG. 1 is a top view of a can end showing a frangible score and other handling damage that can reduce or eliminate the protective coating in localized areas;
FIG. 2 is an illustration of a beverage can seaming operation;
FIG. 3 is a schematic of a beverage can filling and seaming process;
FIG. 4 is an illustration of a filled and seamed beverage can immersed in a solution comprising a corrosion inhibitor;
FIG. 5 is an illustration of the a filled and seamed beverage can being sprayed with a solution comprising a corrosion inhibitor; and
FIG. 6 is a graph summarizing results from a trial carried using principles of the present invention; and
FIG. 7 is a graph summarizing results from a trial carried using principles of the present invention.

DETAILED DESCRIPTION

While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated.
Referring to FIG. 3, an example of a beverage can filling apparatus 100 is schematically represented. In this example, beverage can bodies and end closures are fed to filler and seaming operation where a liquid beverage is introduced into each beverage can body and an end closure is seamed thereto according to the typical method described above and illustrated in FIG. 2.
In a typical system 100, such as the one illustrated, beverage can bodies are depalletized at a depalletizer 108 and fed via a system of conveyors 112 to a rinser 116. The beverage can bodies are rinsed and passed to a filler 120 where the liquid beverage is introduced into each beverage can body. A feeder 122 transports end closures to the filled beverage can bodies and a seamer 124 attaches an end closure to each filled beverage can body. The filled beverage containers undergo a fill check 128 are rinsed a rinse station 132. If required the liquid beverage is pasteurized in the seamed beverage container at a pasteurizer 136. A blower 140 delivers a fluid pressure to the beverage container subsequent to pasteurization. The beverage containers are then rinsed again at a second rinse station 148 and undergo a final fill check 152 and a fluid pressure blow off 156. The filled containers are accumulated at an accumulation table 160, tray loaded with shrink wrap 164, and palletized 178.
The present invention contemplates, rinsing filled and seamed beverage containers with a corrosion inhibitor as part of the typical beverage container filling process. This is not currently done, as deionized water is generally used to rinse the beverage containers in the beverage container filling and seaming process described above. Thus, it follows that a rinsing solution applied to the filled and seamed beverage containers at one or both of the rinse stations 132,148 comprises a corrosion inhibitor. It is contemplated that a water resistant and/or oxidation resistant layer can be formed on the seamed beverage container. For example, the corrosion inhibitor may react with a bare aluminum oxide layer on the end closure 10 to produce a water and oxidation resistant layer. Prior to the development of the present method and use of a corrosion inhibitor solution, beverage can fillers merely used deionized water for removing beverage residues on ends after filling.
The invention contemplates application of the corrosion inhibitor primarily for corrosion resistance on the end closure caused by production of the frangible score or other damage occurring subsequent to forming the end closure and prior to the first rinse at the first rinsing station 132 in the filling and seaming apparatus 100. Application can be accomplished by immersing the end closure 10 and the beverage can body 40 in a bath 182 of a rinsing solution 186 comprising the corrosion inhibitor (FIG. 4) or by spraying the end closure 10 and the beverage can body 40 using a typical spray head 190 and a rinsing solution 186 comprising a corrosion inhibitor (FIG. 5). These steps can take place using the current rinsing stations in place 132,148 or by introducing new stations and/or processes into the filling and seaming system 100.
It follows that in one embodiment the end closure 10 is rinsed in a solution comprising a corrosion inhibitor subsequent to attaching the end closure to the liquid beverage filled beverage can body 40. Using one or both of the application processes described above, i.e. immersion and/or spraying, both the end closure 10 and the beverage can body 40 can be treated with the corrosion inhibitor. This rinsing may occur either prior to or subsequent to pasteurization. Alternatively, the rinsing with the corrosion inhibitor may occur both before and after pasteurization.
In another embodiment, a water resistant layer is formed on a frangible score 22 on an end closure 10 subsequent to attaching the end closure 10 to the beverage can body 40. The water resistant layer can be formed by rinsing the end closure 10 in a solution comprising a corrosion inhibitor. In this embodiment, the beverage can body 40 may also receive the corrosion inhibitor substantially simultaneously (i.e. in the same process step) as the end closure 10. Again, using one or both of the application processes described above, i.e. immersion and/or spraying, both the end closure 10 and the beverage can body 40 can be treated with the corrosion inhibitor. This rinsing may occur either prior to or subsequent to pasteurization. Alternatively, the rinsing with the corrosion inhibitor may occur both before and after pasteurization.
In tests, it was discovered that a solution comprising a corrosion inhibitor slows down the process of stress corrosion. Preferably, a solution of 1.5% Deoxylyte®-444 (Deoxylyte® is trademark of Henkel AG & Co. KGaA of Dusseldorf, Germany) slows down filled and seamed beverage container's susceptibility to stress corrosion cracking as compared to untreated beverage containers and beverage containers treated with a solution comprising a corrosion inhibitor of 0.3% Deoxylyte®-444. During the test, 96 filled and seamed beverage containers were submitted to a laboratory for stress corrosion susceptibility testing with using a 1.5% salt solution. The U-shaped countersink and center panels of each end were filled with 2.0ml of the 1.5% NaCl solution, covered with Para film, and sealed with an elastic band. The filled and seamed beverage containers were stored upright at 35°C for 4 weeks. The beverage containers were examined everyday (except weekends) and any cans with burst frangible scores or loss of gas at the frangible score were noted and removed. The beverage containers were monitored over a period of 6 weeks and a graph indicating the relative performance of the different ends is shown in FIG. 6. The results on day 3 showed a significant difference between the 1.5% Deoxylyte®-444 solution and the 0.3% Deoxylyte®-444 and standard filled and seamed beverage containers.
In further tests, it was discovered that a solution comprising a corrosion inhibitor of 1.5-5% Deoxylyte®-444 combined with an additional water soluble acrylic-based polymer, such as polyacrylate produced better results. Forty-eight beverage filled beverage containers were tested. The beverage containers were commercially filled with carbonated soft drink product and immersed in the solution. The U-shaped countersink and center panels covering the score 22 of each end closure were filled with 2.0ml of a 1.5% NaCl solution and covered with Para film and sealed with an elastic band. They were then stored upright at 37°C for about two weeks (15 days). The cans were examined every day, and any cans with score bursts or loss of gas at the score 22 were noted, removed, and categorized as failures. The table below shows the failure tally for the untreated control group and beverage containers treated with the solution. Table 1: Results of Rinsing Filled Beverage Containers with Deoxylyte®-444/Polyacrylate

Days

2 3 4 5 6 7 8 9 10 11 12 13 14 15 Total Failures

Control

0 6 2 2 2 3 2 2 1 0 2 2 1 2 27

Treated 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

In still further tests, 48 beverage filled beverage containers were tested. Five different solutions were used. The solutions are summarized in Table 2.

Table 2: Test Solutions

Solution	Deoxylyte®-444	Polyacrylate	Rinse with De-ionized Water?
Variable 1	100g/l	100g/l	No
Variable 2	100g/l	100g/l	Yes
Variable
3	50g/l	50g/l	No
Variable
4	25g/l	50g/l	No
Variable
5	150g/l	0	No

Beverage can bodies were commercially filled with carbonated soft drink product. Can ends were double seamed to the filled can bodies, and the filled and seamed can bodies and can ends were immersed in the solutions. The U-shaped countersink and center panels covering the score 22 of each end closure were filled with 2.0ml of a 1.5% NaCl solution and covered with Para film and sealed with an elastic band. They were then stored upright at 37°C for about a month (32 days). The cans were examined every day, and any cans with score bursts or loss of gas at the score 22 were noted, removed, and categorized as failures. The results of this test are summarized in FIG. 7 and in Table 3. In Table 3, the failure tally after each day from day 1 to day 32 is listed in number of failures for each solution.
The words "comprises/comprising" and the words "having/including" when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.
It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.
While the specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the invention and the scope of protection is only limited by the scope of the accompanying Claims.

Claims

A method for reducing the likelihood of corrosion occurring on a beverage container wherein a metallic beverage can body (40) has an end closure (10) attached thereto using the steps of:
filling a beverage can body (40) with a liquid beverage;

placing an end closure (10) with a frangible score (22) defined in the end closure to allow opening of the container over an open end of the beverage can body filled with the beverage; and

attaching the end closure to the beverage can body, characterized by the further step of:
rinsing the end closure in a solution (186) comprising a corrosion inhibitor subsequent to attaching the end closure to the beverage can body.
The method of Claim 1 including the step of:
rinsing the beverage can body (40) in the solution (186) subsequent to attaching the end closure to the beverage can body.
The method of any of the preceding Claims including the step of:
immersing the end closure in a bath (182) of the solution (186) subsequent to attaching the end closure to the beverage can body (40).
The method of any of the preceding Claims including the step of:
immersing the beverage can body (40) in a bath of the solution (186) subsequent to attaching the end closure (10) to the beverage can body.
The method of any of the preceding Claims wherein the solution (186):
comprises deionized water; and/or

comprises 25g/l to 150 g/l of the corrosion inhibitor; and/or

comprises 50 g/l to 200g/l of an acrylic polymer; and/or

forms a water resistant layer;

or any combination thereof.
The method of any of the preceding Claims wherein the solution (186) is delivered by a sprayer (190).
The method of any of the preceding Claims wherein the solution (186) reacts with a bare aluminum oxide layer on the end closure (10) to produce an oxidation resistant layer.
The method of any of the preceding Claims including the step of:
pasteurizing the liquid beverage within the beverage can body (40) wherein the rinsing step is carried out prior to the pasteurizing step.
The method of any of the preceding Claims including the step of:
rinsing the end closure (10) a second time with a solution (186) comprising a corrosion inhibitor subsequent to the pasteurizing step.
The method of any of Claims 1 through 7 including the step of:
pasteurizing the liquid beverage within the beverage can body (40) wherein the rinsing step is carried out subsequent to the pasteurizing step.
The method of any preceding claim wherein the solution (186) comprises an acrylic polymer for example a polyacrylate.