Laminated can end blank

Abstract

Provided herein is a can end stock (CES) and a method for producing a CES. The CES includes a laminated metal strip having a polymeric film coating and beneficially exhibits low feathering, low linting, and high abrasion resistance. The laminated metal strip can include a laminated polymeric coating on an exterior-facing side and a lacquered coating on an interior-facing side. The CES is formed by laminating a polymeric film to one side of the metal strip and annealing the laminated metal strip. In some cases, the polymeric film laminated to the metal strip is a colorable polyethylene terephthalate (PET) film.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit and priority of U.S. Application No. 63 / 178,323, filed April 22, 2021, which is hereby incorporated in its entirety by reference for all purposes. Technical Field

[0003] This disclosure relates generally to metal processing, and more specifically to laminated metal strips suitable for use as can end blanks and their production. Background Technology

[0004] Certain metal products (such as aluminum beverage cans) may require or otherwise benefit from a protective layer between the metal and its contents. For example, beverage cans typically require adequate protection between the metal of the can and the beverage it contains to prevent damage to the metal from strong beverages (such as soda and cola) and to avoid adverse effects on the beverage (such as discoloration or taste changes). Furthermore, metal products may benefit from a protective layer between the metal and the external environment. For instance, an external protective layer on the beverage can protects it from abrasion or other damage during the manufacturing process. An external protective layer on the beverage can may also be necessary or beneficial for incorporating external design elements into the can.

[0005] There are typically requirements for protective layers placed on both the inner and outer surfaces of metal products. For example, the protective layer must adhere adequately to the metal product. As a further example, on the outer surface, the protective layer must generally exhibit uniform color, abrasion resistance, appropriate opening behavior, and suitable general behavior during final manufacturing. Conventional protective layers (such as paint) have been found to exhibit insufficient abrasion resistance. Furthermore, previously attempted alternatives to conventional protective layers have been found to exhibit undesirable fuzzing and feathering. In addition, conventional protective layers exhibit insufficient adhesion to metal products and require expensive and time-consuming production processes. Therefore, conventional protective layers are ineffective. Summary of the Invention

[0006] In some aspects, this disclosure provides a process for preparing a can end blank, the process comprising: preheating a metal strip to a first temperature below 250°C; laminating a polymer film onto a first side of the metal strip to produce a laminated metal strip, wherein the first side of the metal strip corresponds to the outward-facing side of the can end formed by the metal strip; and annealing the laminated metal strip at an annealing temperature greater than 175°C. In some cases, the metal strip is an aluminum strip. In some cases, the polymer film comprises a polyethylene terephthalate film. In some cases, the process further comprises applying an adhesive coating to the metal strip, wherein laminating the polymer film onto the first side of the metal strip comprises laminating the polymer film onto the adhesive coating. In some cases, the polymer film contains a colorant. In some cases, the colorant is selected from the group consisting of carbon black and titanium dioxide. In some cases, the process further comprises applying a paint layer to a second side of the metal strip, wherein the second side of the metal strip corresponds to the inward-facing side of the can end formed by the metal strip. In some cases, the paint comprises an epoxy-based solution, a polyester solution, or a combination thereof. In some cases, the annealing temperature is greater than 225°C. In some cases, the annealing temperature is less than 300°C. In some cases, the process further includes cooling the laminated metal strip after annealing. In some cases, the process further includes applying a lubricant to the laminated metal strip after annealing.

[0007] In some aspects, this disclosure provides a can-end preform product prepared according to the process described herein. In some cases, the first side of the metal strip corresponds to the outward-facing side of the can-end preform product. In some cases, the polymer film has a thickness of less than 150 μm.

[0008] In some aspects, this disclosure provides a beverage can comprising a can body and an end cap, wherein the end cap is formed from a can end blank prepared by any of the processes described above.

[0009] In some aspects, this disclosure provides a system comprising: a preheating furnace for receiving a metal strip and preheating the metal strip to a preheating temperature; a lamination system positioned downstream of the preheating furnace for receiving the metal strip at the preheating temperature and applying a polymer film to a first side of the metal strip, wherein the first side of the metal strip corresponds to the outward-facing side of a can end formed by the metal strip; and an annealing furnace positioned downstream of the lamination system for receiving the laminated metal strip and heating the laminated metal strip at an annealing temperature greater than 200°C. In some cases, the metal strip is an aluminum strip. In some cases, the system further includes an adhesive coating application system for applying an adhesive coating to the metal strip, wherein the lamination system is configured to apply the polymer film to the adhesive coating. In some cases, the lamination system is coupled to a polyethylene terephthalate (PET) film supply source. In some cases, the system further includes a paint application system for applying a paint layer to a second side of the metal strip. In some cases, the annealing temperature is greater than 225°C. In other cases, the annealing temperature is less than 300°C. Attached Figure Description

[0010] The present disclosure is described in detail below with reference to the accompanying drawings, wherein like reference numerals indicate similar parts.

[0011] Figure 1 This is a schematic diagram of a system for preparing can end blanks according to certain aspects of this disclosure.

[0012] Figure 2 yes Figure 1 A close-up side view of the can end blank.

[0013] Figure 3A It is a can end blank sheet according to certain aspects of this disclosure.

[0014] Figure 3B Depicting certain aspects of this disclosure after being cut Figure 3A The blank sheet at the end of the can.

[0015] Figure 3C Depicting certain aspects of this disclosure by Figure 3A A set of can end blanks produced from can end blank sheets.

[0016] Figure 3D Depicting certain aspects of this disclosure, including those by... Figure 3C Beverage cans formed from can end blanks.

[0017] Figure 4It is an isometric sectional view depicting a section of the can end blank according to certain aspects of this disclosure, in multiple layers.

[0018] Figure 5 This is a flowchart depicting a process for preparing can end blanks according to certain aspects of this disclosure.

[0019] Figure 6 This is a schematic diagram of a lamination system according to certain aspects of this disclosure. Detailed Implementation

[0020] This article describes a process and system for producing can end blanks from metal strips (such as aluminum strips). In the process described herein, a polymer film (such as polyethylene terephthalate film) is laminated onto the outside of the metal strip. The resulting can end blank can be used, for example, in beverage cans.

[0021] The can end blanks produced according to the method described herein advantageously exhibit improved properties. In particular, the can end blanks exhibit improved abrasion resistance. Furthermore, the can end blanks described herein have been specifically developed to exhibit low feathering and low fuzzing in addition to high abrasion resistance. As described below, feathering and specific implementations are problems encountered in the development of abrasion-resistant can end blanks. The can end blanks described herein achieve all three aspects: abrasion resistance, low feathering, and low fuzzing.

[0022] Furthermore, the method described herein provides a more efficient means of applying a protective film to a metal strip. Conventional processes typically require multiple process steps. In some cases, conventional processes apply consecutive paint layers for different purposes, such as a protective paint layer and paint layers of different colors. On the other hand, the method described herein achieves both protection and display (e.g., coloring) in a single layer. Moreover, the method described herein eliminates the need for a drying step (e.g., to remove solvents from the paint layer applied to the outer surface of the metal strip). These improvements save both time and cost.

[0023] Definition and description

[0024] As used herein, the terms “invention,” “this invention,” “the invention,” and “this invention” are intended to refer to all the subject matter of this patent application and the following claims. Statements containing these terms should not be construed as limiting the subject matter described herein or limiting the meaning or scope of the patent claims below.

[0025] In this specification, reference is made to alloys identified by aluminum industry names (such as "Series" or "7xxx"). For information on the numbering systems most commonly used to name and identify aluminum and its alloys, see "International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys" or "Registration Record of Aluminum Association Alloy Designations and Chemical Composition Limits for Aluminum Alloys in the Form of Castings and Ingot" published by the Aluminum Association.

[0026] Aluminum alloys are described herein based on their elemental composition as a percentage (wt.%) of the total weight of the alloy. In certain examples of each alloy, the remainder is aluminum, with the total sum of impurities not exceeding 0.15% by weight.

[0027] As used herein, "feathering" refers to the elongation and delamination of a protective layer (e.g., a polymer film) on a metal strip. The degree of feathering is measured by the amount of protective layer (e.g., a polymer film) that extends along the cut edge of the aluminum due to elongation and delamination. Feathering is particularly prone to occur in can-end blanks when cutting discs from can-end blanks to produce can ends. Additionally, feathering is a risk of metal breakage, such as the opening created when opening a beverage can.

[0028] As used herein, "fuzzing" refers to the formation of visible, hair-like deformation within the protective layer (e.g., a polymer film) on a metal strip. Fuzzing is particularly prone to occur in can-end blanks when the protective layer (e.g., the polymer film) is cut through, for example, to create score lines. In some cases, fuzzing is caused by poor adhesion between the protective layer and the metal strip.

[0029] Alloy tempering or tempering is mentioned in this application. For the most commonly used descriptions of alloy tempering, see “American National Standards (ANSI) H35 on Alloy and Temper Designation Systems”. F tempering or tempering refers to the aluminum alloy at the time of manufacture. O tempering or tempering refers to the aluminum alloy after annealing. T1 tempering or tempering refers to the aluminum alloy cooled from a hot work and subjected to natural aging (e.g., at room temperature). T2 tempering or tempering refers to the aluminum alloy cooled from a hot work, subjected to cold working, and subjected to natural aging. T3 tempering or tempering refers to the aluminum alloy subjected to solution heat treatment, cold working, and natural aging. T4 tempering or tempering refers to the aluminum alloy subjected to solution heat treatment and natural aging. T5 tempering or tempering refers to the aluminum alloy cooled from a hot work and subjected to artificial aging (at high temperature). T6 tempering or tempering refers to the aluminum alloy subjected to solution heat treatment and artificial aging. T7 tempering or tempering refers to the aluminum alloy subjected to solution heat treatment and artificial over-aging. T8x temper or tempered refers to aluminum alloys that have undergone solution heat treatment, cold working, and artificial aging. T9 temper or tempered refers to aluminum alloys that have undergone solution heat treatment, artificial aging, and cold working.

[0030] As used herein, unless the context clearly indicates otherwise, “a,” “an,” and “the” means both singular and plural references.

[0031] As used herein, "room temperature" can mean a temperature from about 15°C to about 30°C, such as about 15°C, about 16°C, about 17°C, about 18°C, about 19°C, about 20°C, about 21°C, about 22°C, about 23°C, about 24°C, about 25°C, about 26°C, about 27°C, about 28°C, about 29°C, or about 30°C.

[0032] All ranges disclosed herein should be understood to encompass any and all subranges contained herein. For example, the stated range of “1 to 10” should be considered to include any and all subranges between the minimum value of 1 and the maximum value of 10 (and include both the minimum and maximum values); that is, all subranges that begin with a minimum value of 1 or greater (e.g., 1 to 6.1) and end with a maximum value of 10 or less (e.g., 5.5 to 10).

[0033] metal strip

[0034] This disclosure provides processes and systems for producing can-end blanks from metal strips. More specifically, the methods described herein involve laminating a polymer film onto a first side of a metal strip. The composition of the metal strip on which the polymer film is laminated is not limited. The methods described herein are particularly suitable for, but not limited to, aluminum strips. The polymer film can, for example, be applied to any suitable aluminum alloy, such as continuous coils of aluminum alloys. Suitable aluminum alloys include, for example, 1xxx series, 2xxx series, 3xxx series, 4xxx series, 5xxx series, 6xxx series, 7xxx series, and 8xxx series aluminum alloys.

[0035] As a non-limiting example, exemplary 1xxx series aluminum alloys used as metal strips may include AA1100, AA1100A, AA1200, AA1200A, AA1300, AA1110, AA1120, AA1230, AA1230A, AA1235, AA1435, AA1145, AA1345, AA1445, AA1150, AA1350, AA1350A, AA1450, AA1370, AA1275, AA1185, AA1285, AA1385, AA1188, AA1190, AA1290, AA1193, AA1198, or AA1199. In some cases, aluminum alloys are at least 99.9% pure aluminum (e.g., at least 99.91%, at least 99.92%, at least 99.93%, at least 99.94%, at least 99.95%, at least 99.96%, at least 99.97%, at least 99.98%, or at least 99.99% pure aluminum).

[0036] Non-limiting examples of 2xxx series aluminum alloys used as metal strips may include AA2001, AA2002, AA2004, AA2005, AA2006, AA2007, AA2007A, AA2007B, AA2008, AA2009, AA2010, AA2011, AA2011A, AA2111, AA2111A, AA2111B, AA2012, AA2013, AA2014, and AA2014A. , AA2214, AA2015, AA2016, AA2017, AA2017A, AA2117, AA2018, AA2218, AA2618, AA2618A, AA2219, AA231 9. AA2419, AA2519, AA2021, AA2022, AA2023, AA2024, AA2024A, AA2124, AA2224, AA2224A, AA2324, AA242 4. AA2524, AA2624, AA2724, AA2824, AA2025, AA2026, AA2027, AA2028, AA2028A, AA2028B, AA2028C, AA2 029, AA2030, AA2031, AA2032, AA2034, AA2036, AA2037, AA2038, AA2039, AA2139, AA2040, AA2041, AA20 44. AA2045, AA2050, AA2055, AA2056, AA2060, AA2065, AA2070, AA2076, AA2090, AA2091, AA2094, AA209 5. AA2195, AA2295, AA2196, AA2296, AA2097, AA2197, AA2297, AA2397, AA2098, AA2198, AA2099 or AA2199.

[0037] Non-limiting examples of 3xxx series aluminum alloys used as metal strips may include AA3002, AA3102, AA3003, AA3103, AA3103A, AA3103B, AA3203, AA3403, AA3004, AA3004A, AA3104, AA3204, AA3304, AA3005, AA3005A, AA3105, AA3105A, AA3105B, and AA3007. AA3107, AA3207, AA3207A, AA3307, AA3009, AA3010, AA3110, AA3011, AA3012, AA3012A, AA3013, AA3014, AA3015, AA3016, AA3017, AA3019, AA3020, AA3021, AA3025, AA3026, AA3030, AA3130 or AA3065.

[0038] Non-limiting exemplary 4xxx series aluminum alloys used as metal strips may include AA4004, AA4104, AA4006, AA4007, AA4008, AA4009, AA4010, AA4013, AA4014, AA4015, AA4015A, AA4115, AA4016, AA4017, AA4018, AA4019, AA4020, AA4021, AA4026, AA4032, AA4043, AA4043A, AA4143, AA4343, AA4643, AA4943, AA4044, AA4045, AA4145, AA4145A, AA4046, AA4047, AA4047A, or AA4147.

[0039] Non-limiting exemplary 5xxx series aluminum alloys used as metal strips may include AA5182, AA5183, AA5005, AA5005A, AA5205, AA5305, AA5505, AA5605, AA5006, AA5106, AA5010, AA5110, AA5110A, AA5210, AA5310, AA5016, AA5017, AA5018, AA5018A, AA5019, AA5019A, AA5119, and AA5119A. ,AA5021,AA5022,AA5023,AA5024,AA5026,AA5027,AA5028,AA5040,AA5140,AA5041,AA5042,AA5043,AA5049,AA5 149, AA5249, AA5349, AA5449, AA5449A, AA5050, AA5050A, AA5050C, AA5150, AA5051, AA5051A, AA5151, AA5251, AA52 51A, AA5351, AA5451, AA5052, AA5252, AA5352, AA5154, AA5154A, AA5154B, AA5154C, AA5254, AA5354, AA5454, AA55 54. AA5654, AA5654A, AA5754, AA5854, AA5954, AA5056, AA5356, AA5356A, AA5456, AA5456A, AA5456B, AA5556, AA555 6A, AA5556B, AA5556C, AA5257, AA5457, AA5557, AA5657, AA5058, AA5059, AA5070, AA5180, AA5180A, AA5082, AA518 2. AA5083, AA5183, AA5183A, AA5283, AA5283A, AA5283B, AA5383, AA5483, AA5086, AA5186, AA5087, AA5187 or AA5088.

[0040] Non-limiting exemplary 6xxx series aluminum alloys used as metal strips may include AA6101, AA6101A, AA6101B, AA6201, AA6201A, AA6401, AA6501, AA6002, AA6003, AA6103, AA6005, AA6005A, AA6005B, AA6005C, AA6105, AA6205, AA6305, AA6006, AA6106, AA6206, AA6306, AA6008, AA6009, AA6010, AA6110, AA6110A, AA6011, AA6111, AA6012, AA6012A, AA6013, AA6113, AA6014, AA6015, AA6016, AA6016A, AA6116, AA6018, AA6019, AA6020, AA6021, AA6022, AA6023, AA6024, AA6025, AA6026, AA6027, AA6028, A A6031, AA6032, AA6033, AA6040, AA6041, AA6042, AA6043, AA6151, AA6351, AA6351A, AA6451, AA6951, AA6053, A A6055, AA6056, AA6156, AA6060, AA6160, AA6260, AA6360, AA6460, AA6460B, AA6560, AA6660, AA6061, AA6061A, A A6261, AA6361, AA6162, AA6262, AA6262A, AA6063, AA6063A, AA6463, AA6463A, AA6763, A6963, AA6064, AA6064A, AA6065, AA6066, AA6068, AA6069, AA6070, AA6081, AA6181, AA6181A, AA6082, AA6082A, AA6182, AA6091 or AA6092.

[0041] Non-limiting examples of 7xxx series aluminum alloys used as metal strips may include AA7011, AA7019, AA7020, AA7021, AA7039, AA7072, AA7075, AA7085, AA7108, AA7108A, AA7015, AA7017, AA7018, AA7019A, AA7024, AA7025, AA7028, and AA703. 0.AA7031, AA7033, AA7035, AA7035A, AA7046, AA7046A, AA7003, AA7004, AA7005, AA7009, AA 7010, AA7011, AA7012, AA7014, AA7016, AA7116, AA7122, AA7023, AA7026, AA7029, AA7129, A A7229, AA7032, AA7033, AA7034, AA7036, AA7136, AA7037, AA7040, AA7140, AA7041, AA7049 ,AA7049A,AA7149,AA7204,AA7249,AA7349,AA7449,AA7050,AA7050A,AA7150,AA7250,AA7 055, AA7155, AA7255, AA7056, AA7060, AA7064, AA7065, AA7068, AA7168, AA7175, AA7475, AA7076, AA7178, AA7278, AA7278A, AA7081, AA7181, AA7185, AA7090, AA7093, AA7095 or AA7099.

[0042] Non-limiting exemplary 8xxx series aluminum alloys used as metal strips may include AA8005, AA8006, AA8007, AA8008, AA8010, AA8011, AA8011A, AA8111, AA8211, AA8112, AA8014, AA8015, AA8016, AA8017, AA8018, AA8019, AA8021, AA8021A, AA8021B, AA8022, AA8023, AA8024, AA8025, AA8026, AA8030, AA8130, AA8040, AA8050, AA8150, AA8076, AA807bA, AA8176, AA8077, AA8177, AA8079, AA8090, AA8091, and AA8093.

[0043] In some implementations, the metal strip comprises AA3104, AA5006, AA5182, or combinations thereof.

[0044] Although aluminum alloy products are described throughout this disclosure, the methods and products are applicable to any metal strip. In some embodiments, the metal strip is aluminum, aluminum alloy, magnesium, magnesium-based materials, titanium, titanium-based materials, copper, copper-based materials, steel, steel-based materials, bronze, bronze-based materials, brass, brass-based materials, composite materials, sheets used in composite materials, or any other suitable metal or combination of materials. The product may include monolithic materials as well as non-monolithic materials, such as roll-bonded materials, cladding materials, composite materials, or various other materials. In some examples, the metal article is a metal coil, metal strip, metal plate, metal sheet, metal billet, metal ingot, etc.

[0045] The metal strip can be prepared from any alloy that is suitable for tempering. In some examples, the alloy can be used in tempering with F, O, T3, T4, T6, or T8x. The alloy can be produced by direct cooling casting (including direct cooling co-casting) or semi-continuous casting, continuous casting (including, for example, by using a twin-belt casting machine, a twin-roll casting machine, a block casting machine, or any other continuous casting machine), electromagnetic casting, hot-top casting, or any other casting method.

[0046] polymer film

[0047] The process described herein, and the can end blank produced therefrom, includes laminating a polymer film onto a metal strip. Specifically, the process disclosed herein includes laminating the polymer film onto a side of the metal strip corresponding to the outward-facing side of the can end formed by the metal strip (e.g., a first side). Thus, the polymer film forms a portion of the common side of the can end blank.

[0048] As further detailed in the examples below, the use of a polymer film (e.g., instead of paint) on the outward-facing side of the can end advantageously improves the quality of the can-end product. In particular, the polymer film exhibits higher abrasion resistance compared to conventional can-end products. Furthermore, the polymer films described herein, especially those processed according to the production methods described herein, demonstrate reduced feathering and / or fuzzing.

[0049] Polymer films are not particularly limited and may contain any polymer suitable for the desired use of the can-end preform (e.g., as a beverage can). Suitable polymers for polymer films include, for example, polyethylene, polypropylene, and polyethylene terephthalate (PET). In some cases, the polymer film laminated to the metal strip is a biaxially oriented polymer, such as biaxially oriented polyethylene terephthalate (BoPET) film.

[0050] In some embodiments, the polymer film also contains a colorant, such as a dye or colorant. In other words, the polymer film can be a colored polymer film (e.g., a colored PET film). As further detailed in the examples below, it has been found that the use of colored polymer films advantageously improves the quality of canned products. Compared to colorless polymer films, colored films have been found to exhibit a lower tendency to fuzz. Without being bound by theory, it can be considered that the presence of colorant particles in the film affects the film composition, thereby facilitating smooth film breakage (e.g., when forming an opening when opening a beverage can).

[0051] The colorants used in coloring polymer films are not particularly limited. Suitable colorants include, for example, titanium dioxide (e.g., for producing white polymer films) and carbon black (e.g., for producing black polymer films).

[0052] In some embodiments, the average thickness of the polymer film is from 5 μm to 150 μm, for example, 5 μm to 125 μm, 5 μm to 100 μm, 5 μm to 75 μm, 5 μm to 50 μm, 5 μm to 25 μm, 6 μm to 150 μm, 6 μm to 125 μm, 6 μm to 100 μm, 6 μm to 75 μm, 6 μm to 50 μm, 6 μm to 25 μm, 8 μm to 150 μm, 8 μm to 125 μm, 8 μm Up to 100μm, 8μm to 75μm, 8μm to 50μm, 8μm to 25μm, 10μm to 150μm, 10μm to 125μm, 10μm to 100μm, 10μm to 75μm, 10μm to 50μm, 10μm to 25μm, 12μm to 150μm, 12μm to 125μm, 12μm to 100μm, 12μm to 75μm, 12μm to 50μm or 12μm to 25μm.

[0053] Regarding the lower limit, the average thickness of the polymer film can be greater than 5 μm, for example, greater than 6 μm, greater than 8 μm, greater than 10 μm, or greater than 12 μm. Regarding the upper limit, the average thickness of the polymer film can be less than 150 μm, for example, less than 125 μm, less than 100 μm, less than 75 μm, less than 50 μm, or less than 25 μm.

[0054] Examples of suitable average thicknesses for polymer films include 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, 33 μm, and 34 μm. Thicknesses of 35μm, 36μm, 37μm, 38μm, 39μm, 40μm, 41μm, 42μm, 43μm, 44μm, 45μm, 46μm, 47μm, 48μm, 49μm, 50μm, 51μm, 52μm, 53μm, 54μm, 55μm, 56μm, 57μm, 58μm, 59μm, 60μm, and any thickness in between.

[0055] In some embodiments, the process of this disclosure includes laminating a multilayer polymer film onto a metal strip. In these embodiments, each polymer film may independently be a polymer film as described above. In some cases, a multilayer polymer film is laminated onto the metal strip, and each layer is identical (e.g., in terms of composition, colorant, and / or thickness). In some cases, a multilayer polymer film is laminated onto the metal strip, and each layer is different (e.g., in terms of composition, colorant, and / or thickness).

[0056] Adhesive coating

[0057] In some embodiments, the can end preform produced according to this disclosure includes an adhesive coating. Specifically, the adhesive coating may be applied to a metal strip, and a polymer film may be laminated onto the adhesive coating. The adhesive coating advantageously secures the polymer film to the metal strip.

[0058] As illustrated in the examples below, adhesive coatings can provide improved feathering properties. In particular, the adhesion between the polymer film and the metal strip can be controlled (e.g., improved) by selecting an appropriate adhesive coating and by controlling process parameters such as annealing temperature, as described below.

[0059] In some implementations, the adhesive coating is a pretreatment applied to the metal strip, such as a pretreatment suitable for the metal strip. Commercial examples of suitable pretreatments that can be used as adhesive coatings include Addibond 712-CP 30 from Solvay (Brussels, Belgium).

[0060] Wax coating

[0061] In some embodiments, the can-end preforms produced according to this disclosure include a wax coating. In some cases, for example, the wax coating may be applied to the outward-facing surface of the polymer film. The wax coating advantageously improves the appearance of the can-end preform. In particular, the wax coating according to this disclosure exhibits a uniform appearance with minimal streaks or no streaks in its appearance. Additionally, the wax coating acts as a lubricant to reduce friction on the surface. Lubrication may be required to ensure proper operation of the machinery used in the production of the can-end preform.

[0062] The wax coating may comprise a wax solution, such as carnauba wax. Commercial examples of suitable wax products for use as a wax coating include LUBA-print965-A from Münzing (Abstadt, Germany). In some embodiments, the wax coating comprises a diluted solution of carnauba wax in water. For example, the wax coating may comprise a diluted solution of carnauba wax (e.g., LUBA-print965-A) to water at a volume ratio of 1:2 to 1:50 (e.g., 1:5, 1:6, 1:8, 1:10, 1:12, 1:14, 1:16, 1:18, or 1:20). Diluting the wax coating ensures that it can be pumped into the roll gap during commercial applications and reduces foaming, which has been found to dry and produce solid carnauba wax particles on the surface of the can-end blank.

[0063] In some implementations, the average thickness of the wax coating is 5 mg / m². 2 Up to 150 mg / m 2 For example, 5mg / m 2 Up to 120 mg / m 2 5mg / m 2 Up to 115 mg / m 2 5mg / m 2 Up to 110 mg / m 2 5mg / m 2 Up to 105 mg / m 2 5mg / m 2 Up to 100 mg / m 2 6mg / m 2 Up to 150 mg / m 2 6mg / m 2 Up to 120 mg / m 2 6mg / m 2 Up to 115 mg / m 2 6mg / m 2 Up to 110 mg / m 2 6mg / m 2 Up to 105 mg / m 2 6mg / m 2 Up to 100 mg / m 2 7mg / m 2Up to 150 mg / m 2 7mg / m 2 Up to 120 mg / m 2 7mg / m 2 Up to 115 mg / m 2 7mg / m 2 Up to 110 mg / m 2 7mg / m 2 Up to 105 mg / m 2 7mg / m 2 Up to 100 mg / m 2 8mg / m 2 Up to 150 mg / m 2 8mg / m 2 Up to 120 mg / m 2 8mg / m 2 Up to 115 mg / m 2 8mg / m 2 Up to 110 mg / m 2 8mg / m 2 Up to 105 mg / m 2 8mg / m 2 Up to 100 mg / m 2 9mg / m 2 Up to 150 mg / m 2 9mg / m 2 Up to 120 mg / m 2 9mg / m 2 Up to 115 mg / m 2 9mg / m 2 Up to 110 mg / m 2 9mg / m 2 Up to 105 mg / m 2 9mg / m 2 Up to 100 mg / m 2 10mg / m 2 Up to 150 mg / m 2 10mg / m 2 Up to 120 mg / m 2 10mg / m 2 Up to 115 mg / m 2 10mg / m 2 Up to 110 mg / m 2 10mg / m 2 Up to 105 mg / m 2 Or 10mg / m 2 Up to 100 mg / m 2 .

[0064] As for the lower limit, the average thickness of the wax coating can be greater than 5 mg / m.2 For example, greater than 6 mg / m³ 2 Greater than 7mg / m 2 Greater than 8mg / m 2 Greater than 9mg / m 2 or greater than 10 mg / m 2 In terms of upper limits, the average thickness of the wax coating can be less than 125 mg / m². 2 For example, less than 120 mg / m 2 Less than 115mg / m 2 Less than 110 mg / m 2 Less than 105 mg / m 2 or less than 100 mg / m 2 .

[0065] paint

[0066] In some embodiments, the can end blank produced according to this disclosure includes a paint layer. In some cases, for example, the paint layer may be applied to the surface of the metal strip, such as the inward-facing surface. In these embodiments, the paint forms a protective layer between the metal strip and the contents of the can end blank (e.g., the contents of a beverage can formed from the can end blank).

[0067] The compositions of paints suitable for the processes described herein are not particularly limited. In some cases, the paint comprises a water-based and / or solvent-based composition, which is preferably applicable to the surface of the metal strip by spraying, pouring, or otherwise. In some embodiments, the paint applied to the surface of the metal strip comprises an epoxy-based solution, a polyester solution, or a combination thereof. Commercial examples of compositions suitable for use as paints of this disclosure include EzDex from Sherwin-Williams (Cleveland, Ohio).

[0068] In some embodiments, the average thickness of the paint layer is 2 μm to 20 μm, for example, 2 μm to 18 μm, 2 μm to 16 μm, 2 μm to 14 μm, 2 μm to 12 μm, 2 μm to 10 μm, 3 μm to 20 μm, 3 μm to 18 μm, 3 μm to 16 μm, 3 μm to 14 μm, 3 μm to 12 μm, 3 μm to 10 μm, 4 μm to 20 μm, 4 μm to 18 μm. 4μm to 16μm, 4μm to 14μm, 4μm to 12μm, 4μm to 10μm, 5μm to 20μm, 5μm to 18μm, 5μm to 16μm, 5μm to 14μm, 5μm to 12μm, 5μm to 10μm, 6μm to 20μm, 6μm to 18μm, 6μm to 16μm, 6μm to 14μm, 6μm to 12μm, or 6μm to 10μm.

[0069] Regarding the lower limit, the average thickness of the paint layer can be greater than 2 μm, for example, greater than 3 μm, greater than 4 μm, greater than 5 μm, or greater than 6 μm. Regarding the upper limit, the average thickness of the paint layer can be less than 20 μm, for example, less than 18 μm, less than 16 μm, less than 14 μm, less than 12 μm, or less than 10 μm.

[0070] Examples of suitable average thicknesses for the coating include 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, and 20μm, and any thickness in between.

[0071] In some cases, the thickness of the paint layer can be expressed in terms of basis weight. In some embodiments, the basis weight of the paint layer is 1 g / m³. 2 Up to 15g / m2, for example, 1g / m 2 Up to 14g / m 2 1g / m 2 Up to 12g / m 2 1g / m 2 Up to 10g / m 2 1g / m 2 Up to 8g / m 2 1g / m 2 Up to 6g / m 2 1.5g / m 2 Up to 15g / m 2 1.5g / m 2 Up to 14g / m 2 1.5g / m 2 Up to 12g / m 2 1.5g / m 2 Up to 10g / m 2 1.5g / m 2 Up to 8g / m 2 1.5g / m 2 Up to 6g / m 2 2g / m 2 Up to 15g / m 2 2g / m 2 Up to 14g / m 2 2g / m 2 Up to 12g / m 2 2g / m 2 Up to 10g / m 2 2g / m 2 Up to 8g / m 2 2g / m 2 Up to 6g / m 2 2.5g / m 2 Up to 15g / m 22.5g / m 2 Up to 14g / m 2 2.5g / m 2 Up to 12g / m 2 2.5g / m 2 Up to 10g / m 2 2.5g / m 2 Up to 8g / m 2 2.5g / m 2 Up to 6g / m 2 3g / m 2 Up to 15g / m 2 3g / m 2 Up to 14g / m 2 3g / m 2 Up to 12g / m 2 3g / m 2 Up to 10g / m 2 3g / m 2 Up to 8g / m 2 or 3g / m 2 Up to 6g / m 2 .

[0072] As for the lower limit, the basis weight of the paint layer can be greater than 1 g / m³. 2 For example, greater than 1.5g / m 2 Greater than 2g / m 2 Greater than 2.5g / m 2 or greater than 3g / m 2 In terms of upper limits, the basis weight of the paint layer can be less than 15 g / m³. 2 For example, less than 14g / m 2 Less than 12g / m 2 Less than 10g / m 2 Less than 8g / m 2 or less than 6g / m 2 .

[0073] Examples of suitable basis weights for paint coatings include 1 g / m³. 2 1.5g / m 2 2g / m 2 2.5g / m 2 3g / m 2 3.5g / m 2 4g / m 2 4.5g / m 2 5g / m 2 5.5g / m 2 6g / m 2 6.5g / m 2 7g / m 2 7.5g / m 28g / m 2 9g / m 2 10g / m 2 11g / m 2 12g / m 2 13g / m 2 14g / m 2 15g / m 2 And any thickness in between.

[0074] In some embodiments, the can end blank produced according to this disclosure includes an adhesive coating between a metal strip and a paint layer. Specifically, the adhesive coating may be applied to the metal strip, and the paint may be applied onto the adhesive coating. The adhesive coating advantageously bonds the paint to the metal strip. In some embodiments, the adhesive coating is a pretreatment applied to the metal strip, e.g., a pretreatment suitable for the metal strip. The adhesive coating between the metal strip and the paint layer may be the same as or different from the adhesive coating between the polymer film and the metal strip. Commercial examples of suitable pretreatments that can be used as the adhesive coating between the metal strip and the paint include titanium-zirconium (Ti-Zr) based pretreatments, such as Bonderite from Henkel Adhesive Technologies (Düsseldorf, Germany).

[0075] Processes and systems for preparing can end blanks

[0076] In some aspects, this disclosure provides processes for preparing can-end blanks. The methods described herein advantageously produce laminated can-end blanks with low feathering and low fuzzing. In some embodiments, the methods described herein produce laminated can-end blanks that also exhibit high performance in other test parameters, such as in acetic acid tests, which can evaluate the corrosion resistance of the laminate under acidic conditions that may lead to delamination. These processes may include laminating a polymer film onto a metal strip and annealing the laminated metal strip at an annealing temperature (T2), and may further include preheating the metal strip to a preheating temperature (T1) prior to laminating the polymer film onto the metal strip. According to the process of this disclosure, annealing the laminated metal strip includes heating to a temperature T2 greater than 175°C. Without being bound by theory, it can be considered that annealing at these temperatures improves the adhesion of the polymer film to the metal strip, and thereby greatly improves the performance characteristics of the produced can-end blank.

[0077] In some embodiments, coating is applied to both sides of the metal strip. In embodiments according to this disclosure, the metal strip may be laminated on one side and painted on the opposite side. For example, the metal strip may be laminated on the inward-facing side and painted on the outward-facing side, but other configurations may also be used. This hybrid laminated / painted metal strip can provide improved functional properties inside the can end preform by using paint, while maintaining high aesthetic and functional properties on the exterior of the can end preform by using a polymer film that may be prone to fuzzing. In some cases, as described above, the polymer film may contain additives, such as colorants, which provide color to the film and have been found to improve the performance characteristics of the can end preform.

[0078] In some cases, the laminated metal strip is fed directly from the lamination process to the annealing process (e.g., into an annealing furnace). In other cases, the laminated metal strip is fed directly from the lamination process to the paint application system and then to the annealing process (e.g., into an annealing furnace). In some cases, the laminated metal blank is quenched (e.g., air-quenched or water-quenched) before entering the paint application system.

[0079] In some conventional processes used to prepare can end blanks, both sides of the metal strip are coated with paint. Because the paint composition has a relatively high solvent content, it is not possible to apply the paint to both sides of the metal strip and simultaneously anneal it in a furnace. Furthermore, the high solvent content of the paint composition necessitates an additional drying step. Therefore, conventional processes typically require multiple process steps to apply and dry the paint composition. This limits production line speed and requires additional passes during production, thus increasing costs.

[0080] This document describes the processes and systems described herein, along with their various additional features and examples, with reference to the accompanying drawings. In the drawings, the same reference numerals indicate the same elements, and directional descriptions are used to describe illustrative embodiments, but, as with illustrative embodiments, are not intended to limit this disclosure. Elements included in the illustrations herein may not be drawn to scale.

[0081] Figure 1This is a schematic diagram of a system 100 for preparing can end preforms (CES) according to certain aspects of this disclosure. A metal strip 102 is fed into a preheating furnace 112, which heats the metal strip 102 to a preheating temperature (T1). The preheating temperature T1 is much lower than the melting temperature of the polymer film 120 to be laminated to the metal strip 102. In some implementations, the preheating temperature T1 is a temperature ranging from 175°C to 300°C, for example, 175°C to 290°C, 175°C to 280°C, 175°C to 270°C, 175°C to 260°C, 175°C to 250°C, 185°C to 300°C, 185°C to 290°C, 185°C to 280°C, 185°C to 270°C, 185°C to 260°C, 185°C to 250°C, 195°C to 300°C, 195°C to 290°C, 195°C to 280°C, 195°C to 270°C, 195°C to 260°C. The temperatures range from 195°C to 250°C, 205°C to 300°C, 205°C to 290°C, 205°C to 280°C, 205°C to 270°C, 205°C to 260°C, 205°C to 250°C, 215°C to 300°C, 215°C to 290°C, 215°C to 280°C, 215°C to 270°C, 215°C to 260°C, 215°C to 250°C, 225°C to 300°C, 225°C to 290°C, 225°C to 280°C, 225°C to 270°C, 225°C to 260°C, or 225°C to 250°C. For the lower limit, T1 can be greater than 175°C, for example, greater than 185°C, greater than 195°C, greater than 205°C, or greater than 215°C. In terms of upper limits, T1 can be less than 300°C, for example, less than 290°C, less than 280°C, less than 270°C, less than 260°C, or less than 250°C.

[0082] In some implementations, the surface of the metal strip 102 may be degreased (e.g., using an acid solution, such as sulfuric acid, hydrofluoric acid, phosphoric acid, or a combination thereof) to clean the surface before it enters the preheating furnace.

[0083] A preheated metal strip 104 enters a lamination system 114. As a preheated metal strip 104, a metal strip 102 passes through the lamination system 114, which applies a polymer film 120 to one side of the metal strip 102. In some cases, the polymer film may be applied to both sides of the metal strip 102. The lamination system 114 can be any suitable system for laminating the polymer film 120 to the metal strip 102. In some cases, the lamination system 114 is a hot-melt lamination system. The laminated metal strip 106 exits the lamination system 114, thereby bonding the metal strip 102 to the polymer film 120.

[0084] In some cases, the laminated metal strip 106 may enter the paint application system 116. The laminated metal strip 106 may be cooled (e.g., air-cooled or water-quenched) before entering the paint application system 116. Paint 124 is applied to the laminated metal strip 102 by the paint application system 116. The paint application system 116 can be any suitable system for applying paint 124 to the metal strip 102. The paint application system 116 may include a furnace for heating or curing paint 124 onto the laminated metal strip 102. In some cases, the paint application system 116 is downstream of the lamination system 114 (e.g., after the lamination system). In some cases, the paint application system 116 is upstream of the annealing furnace 118 (e.g., before the annealing furnace). In some cases, the paint application system 116 is upstream of the lamination system 114 or the preheating furnace 112. In some cases, the paint application system 116 is downstream of both the lamination system 114 and the annealing furnace 118. Figure 1 In the illustrated embodiment, the paint application system 116 is located between the lamination system 114 and the annealing furnace 118. The laminated and painted metal strip 108 can then leave the paint application system 116.

[0085] When the upstream paint system 116 is used, the laminated and painted metal strip 108 can enter the annealing furnace 118. In some cases, the laminated metal strip 106 can enter the annealing furnace without using the paint application system 116 between the lamination system 114 and the annealing furnace 118.

[0086] Annealing furnace 118 may be located downstream (e.g., after) of lamination system 114 and optionally paint application system 116. In some cases, annealing furnace 118 is located immediately downstream of paint application system 116, such that the painted laminated metal strip 108 leaving paint application system 116 enters annealing furnace 118 before entering or contacting other machinery or systems.

[0087] Annealing furnace 118 raises the temperature of the coated laminated metal strip 108 to the annealing temperature (T2). In some embodiments, the annealing temperature T2 is a temperature ranging from 175°C to 300°C, for example, 175°C to 290°C, 175°C to 280°C, 175°C to 270°C, 175°C to 260°C, 175°C to 250°C, 185°C to 300°C, 185°C to 290°C, 185°C to 280°C, 185°C to 270°C, 185°C to 260°C, 185°C to 250°C, 195°C to 300°C, 195°C to 290°C, 195°C to 280°C, 195°C to 270°C, 195°C to 260°C. The temperatures range from 195°C to 250°C, 205°C to 300°C, 205°C to 290°C, 205°C to 280°C, 205°C to 270°C, 205°C to 260°C, 205°C to 250°C, 215°C to 300°C, 215°C to 290°C, 215°C to 280°C, 215°C to 270°C, 215°C to 260°C, 215°C to 250°C, 225°C to 300°C, 225°C to 290°C, 225°C to 280°C, 225°C to 270°C, 225°C to 260°C, or 225°C to 250°C. For the lower limit, T2 can be greater than 175°C, for example, greater than 185°C, greater than 195°C, greater than 205°C, or greater than 215°C. In terms of upper limits, T2 can be less than 300°C, for example, less than 290°C, less than 280°C, less than 270°C, less than 260°C, or less than 250°C.

[0088] The coated laminated metal strip 108 is subjected to an annealing furnace 118 for a sufficient duration to impart desired properties to the coated laminated metal strip 108, including annealing of the metal strip 102 and desired adhesion of the polymer film 120. The duration within the annealing furnace 118 can be based on the furnace length and the speed of the metal strip. In some cases, the duration can range from about 2 seconds to about 30 seconds, from about 9 seconds to about 15 seconds, from about 10 seconds to about 14 seconds, or about 12 seconds. In some cases, the duration can be adjusted as needed (e.g., by adjusting the speed of the metal strip) to compensate for temperature variations within the annealing furnace 118.

[0089] After leaving the annealing furnace 118, the can end blank 110 (e.g., an annealed, painted, and laminated metal strip) may optionally be quenched, such as with air or a quenching liquid (e.g., water) or by applying a coolant to the can end blank 110. The can end blank 110 may be cooled immediately after leaving the annealing furnace 118 by quenching or other means.

[0090] In some cases, the can end blank 110 produced by system 100 may include a metal strip 102, to which a laminated polymer film layer 120 has been applied, and a paint layer 124 has been applied to a second side of the metal strip, such as... Figure 1 and Figure 2 As shown.

[0091] In some cases, the metal strip 102 may include one or more adhesive coatings, as described above. In some embodiments, for example, one or more adhesive coatings may be pre-applied before entering the preheating furnace 112 or lamination system 114.

[0092] In some cases, a wax coating may be applied to the can end blank 110 after it has left the annealing furnace 118.

[0093] Figure 2 yes Figure 1 A close-up side view of the can end blank 110. The can end blank 110 includes a metal strip 102 sandwiched between a laminated polymer film 120 and a paint layer 124.

[0094] As described above, in some cases, to prepare the metal strip to provide enhanced adhesion properties, one or more layers of adhesive coating 202 may be applied to the bare metal. This adhesive coating 202 provides enhanced adhesion, low whitening after pasteurization, and good corrosion resistance in acetic acid testing. In some cases, the metal strip 102 may include one or more adhesive coatings 202 located between one or both of the laminated polymer film 120 and the varnish layer 124.

[0095] Figures 3A to 3D This is an isometric depiction of can end blank 302 at various stages of production. In some cases, can end blank 302 is a can end blank as described herein, including laminated polymer films and paints.

[0096] Figure 3A It is the can-end blank sheet 302 according to certain aspects of this disclosure. The can-end blank sheet 302 can be Figure 1 The can end blank 110 or similar can end blank is depicted in the figure. Figure 3B Depicting the scene after cutting Figure 3B The can end blank sheet 302. The can end blank sheet 302 may be die-cut, perforated, or otherwise cut to produce, as... Figure 3C The can end blank 306 shown is shown. Figure 3C Depicting by Figure 3A A set of can end blanks 306 produced from can end blank sheets. Figure 3D Depicting including by Figure 3C The beverage can 310 is formed from the can end blank 306 to the can end 308.

[0097] The can end 308 includes an outward-facing side (e.g., in...). Figure 3D(See the outside) and the inside side (e.g., facing the inside of beverage can 310). As described herein, the can end 308 may be formed such that the laminated polymer film is present on the outside side and the paint layer is present on the inside side, but this is not necessary.

[0098] Figure 4 This is an isometric cross-sectional view depicting multiple layers of a section of a can end blank 400 according to the present disclosure. The can end blank 400 may include a metal layer 404 (such as aluminum (e.g., an aluminum alloy)) and a paint layer 406 surrounded by a laminated polymer film 402. The can end blank 400 may be... Figure 1 The can end blank 110.

[0099] Figure 5 This is a flowchart depicting a process 500 for preparing a can end blank according to an embodiment of the present disclosure. At box 502, a metal strip is provided. The metal strip may be an aluminum strip suitable for forming a can end blank. The surface of the metal strip may optionally be degreased (e.g., using an acid solution). At box 503, an adhesive coating is optionally applied to the metal strip. At box 504, the metal strip is preheated to a preheating temperature T1. At box 506, the metal strip is laminated with a polymer film (e.g., a PET film). At box 508, a wax coating is optionally applied to one or both sides of the metal strip. At box 510, the laminated metal strip is annealed at an annealing temperature T2. In box 512, the annealed metal strip is optionally quenched.

[0100] Figure 6 This is a schematic diagram of a lamination system 614 according to certain aspects of this disclosure. The lamination system 614 can be... Figure 1 The lamination system 114 or another lamination system. Figure 6 Some of the elements depicted are shown at an enlarged scale for illustrative purposes only.

[0101] The lamination system 614 may include a pair of rollers 652 through which a preheated metal strip 604 may pass. The rollers 652 may be made of any suitable material, such as rubber or metal (e.g., steel). In some cases, one of the rollers 652 (e.g., a roller on the polymer film side) is made of rubber, and the other of the rollers 652 (e.g., a roller on the opposite side) is made of steel. The preheated metal strip 604 may include materials that have already been passed through, such as... Figure 1 The metal strip 602 is preheated in the preheating furnace 112. In some cases, the preheated metal strip 604 includes one or more conversion layers 603.

[0102] As the polymer film 624 passes through roller 652, it can be pressed onto the preheated metal strip 604 to produce a laminated metal strip 606. In some cases, the individual lamination system 614 may include additional roller sets to apply a second polymer film to the side of the preheated metal strip 604 opposite to the polymer film 624. In some cases, roller 652 may additionally apply a second polymer film to the side of the preheated metal strip 604 opposite to the polymer film 624.

[0103] Characteristics of can-end blanks

[0104] As described above, the can end blanks of the present invention (e.g., can end blanks produced according to the described process) advantageously exhibit many improved properties.

[0105] In some embodiments, the can end blanks of this disclosure exhibit low burring. As defined above, burring refers to visible, hair-like deformation forming in the protective layer (e.g., polymer film) on the metal strip, particularly at fractures in the metal (such as openings created when a beverage can is opened). Burring has been found to be particularly problematic during the development of the can end blanks of this disclosure. In some cases, burring can be visible and make the can end blank unsightly and unsuitable for commercial use. In some cases, burring can lead to corrosion of the can end blank. In early tests (detailed below), can end blanks with a polymer film on the outer surface exhibited burring.

[0106] However, the can end preforms of this disclosure overcome the fuzzing problem. In some embodiments, the can end preforms do not exhibit severe (e.g., visible) fuzzing. In particular, embodiments of can end preforms having a colored (e.g., black or white) polymer film are particularly resistant to fuzzing. In some cases, can end preforms including a colorless (e.g., transparent) outer coating exhibit fuzzing in the score line area during can opening. Embodiments including a colored (e.g., black or white) polymer film exhibit a significantly reduced tendency to fuzz. Without being bound by theory, it can be considered that the colorant (e.g., carbon black or titanium dioxide) particles in the polymer film contribute to smooth film rupture.

[0107] In some respects, can end blanks exhibit low or no burring during the can end making process. For example, conventional can ends may be particularly prone to burring during the stamping of notches (e.g., V-shapes). However, the can end blanks of this disclosure exhibit low or no burring during such a process.

[0108] In some respects, the can-end preforms exhibit low or no fuzzing during opening. Here, we conducted tests under pristine conditions and after a pasteurization process. For example, conventional can ends may be particularly prone to fuzzing when opening beverage cans. However, the can-end preforms of this disclosure exhibit low or no fuzzing during such a process.

[0109] In some embodiments, the can-end preforms of this disclosure exhibit improved adhesion. In some cases, for example, the can-end preforms of this disclosure exhibit improved results in a 3% acetic acid test. As used herein, the 3% acetic acid test may include evaluating the coating's resistance to a diluted acidic medium at about 100°C for 30 minutes. The test may include cutting cross-shaded lines on the sample and immersing the sample in a 3% acetic acid solution at about 100°C for 30 minutes, then removing the sample and cooling it. After cooling, another set of cross-cuts is made on each sample, and tape is placed on the cross-shaded areas before and after the acid bath and steadily removed at an angle of about 60° within 0.5 to 1 second. The test results (e.g., based on the presence and strength of delamination) can be used to determine whether the metal strip is acceptable or unacceptable at a given desired specification. The degree of delamination is observed and evaluated on a scale from 1 (lowest degree of delamination) to 5 for the degree of delamination. As used herein, if a sample exhibits no or low delamination, the sample passes the 3% acetic acid test.

[0110] Conventional metal strips (e.g., metal strips with a paint layer applied to the outer surface) typically score poorly in the 3% acetic acid test. In some cases, the annealed laminated can-end blanks disclosed herein achieve more favorable results in the 3% acetic acid test compared to standard painted can-end blanks (e.g., low or no delamination). In some cases, the can-end blanks disclosed herein pass the 3% acetic acid test with low delamination. In some cases, the annealed laminated can-end blanks disclosed herein pass the 3% acetic acid test without delamination.

[0111] In some embodiments, the can end blanks of this disclosure exhibit reduced feathering. In some cases, for example, the can end blanks of this disclosure exhibit improved results in standard feathering tests. As used herein, a standard feathering test can be performed on the can end and may include immersing the can end in a deionized water bath at approximately 75°C for thirty minutes, rinsing the can end with cold deionized water to restore it to room temperature, and then immediately opening the end pull ring of the can end. Feathering can be observed and measured on a notched panel or barn opening. In some cases, the feathering test can be performed on a flat metal sheet (such as a flat can end blank sheet). In such cases, the feathering test may include immersing the sample in demineralized water at 80°C for forty minutes, then allowing the sample to cool to room temperature, and cutting the sample, which can be separated by pulling the metal strip in a direction away from the cut. In any feathering test, the amount of feathering can be measured, and can end blanks exhibiting a maximum amount of feathering less than 0.7 mm are considered to pass the test.

[0112] In some examples, the can-end preforms described herein passed standard feathering tests. In some embodiments, the can-end preforms exhibit a maximum feathering of less than 0.7 mm (e.g., less than 0.6, less than 0.5 mm, less than 0.4 mm, less than 0.3 mm, or less than 0.2 mm). This feathering may be located at certain indicated positions along the orifice of the open can end. The feathering of the membrane also depends on the design of the product's cutting, forming, and stamping tools.

[0113] In some embodiments, the can-end blanks of this disclosure exhibit improved wear resistance. In some cases, for example, the can-end blanks exhibit a weight reduction of less than 0.25% after exposure to 2000 cycles of tribological wear, such as less than 0.2%, less than 0.15%, less than 0.14%, less than 0.13%, less than 0.12%, less than 0.11%, or less than 0.1%.

[0114] Example

[0115] The following examples are intended to further illustrate the invention, but do not constitute any limitation thereof. Rather, it should be clearly understood that various embodiments, modifications, and equivalents of the invention may be taken, and these embodiments, modifications, and equivalents will be apparent to those skilled in the art upon reading this specification without departing from the spirit of the invention.

[0116] Example 1: Can-end blank

[0117] Several samples of can end blanks were prepared according to the disclosed method. Samples were prepared using AA5182 aluminum alloy with a gauge of 0.208 mm as the metal strip. Samples for each test are shown in Table 1. Each sample underwent pretreatment as shown in Table 1, and the can end blanks were prepared by laminating a polymer film onto the first side (exterior), applying a paint layer to the second side (interior), and annealing at an annealing temperature. A comparative sample (A) was also prepared using AA5182 aluminum alloy, but by applying a paint layer to the first side (exterior), laminating a polymer film onto the second side (interior), and annealing at an annealing temperature.

[0118] Table 1

[0119]

[0120]

[0121] To evaluate the performance of the above-mentioned sample can-end blanks, various tests were performed. For adhesion assessment, each sample was tested according to the 3% acetic acid test described above. The observed degree of delamination was evaluated on a scale from 1 (minimum delamination) to 5. Grade 1 indicates no delamination observed. Grade 2 indicates a delamination area less than 5% of the sample. Grade 3 indicates a delamination area between 5% and 15% of the sample. Grade 4 indicates a delamination area greater than 15% of the sample. Grade 5 indicates the sample exhibits complete delamination. Grades 1 or 2 are considered acceptable, Grade 3 is considered barely acceptable, and Grades 4 or 5 are considered unacceptable. The results of this test are shown in Table 2.

[0122] To evaluate feathering, the above test was performed by immersing the samples in demineralized water at 80°C for forty minutes. Samples from exemplary can-end blanks were tested before and after pasteurization. Maximum feathering less than 0.7 mm was considered acceptable, maximum feathering between 0.7 mm and 0.8 mm was considered barely acceptable, and maximum feathering greater than 0.8 mm was considered unacceptable. The results of this test are also shown in Table 2.

[0123] To assess fuzzing, the can end blank was observed for visible fuzzing during joining and / or opening. Each sample was assigned a grade from 1 to 3. Grade 1 indicates no fuzz and is considered acceptable. Grade 2 indicates small fuzz and is considered barely acceptable. Grade 3 indicates long fuzz and is considered unacceptable. The results of these tests are shown in Table 3.

[0124] Table 2

[0125]

[0126]

[0127] The tested samples (samples 1 to 9) exhibited excellent adhesion, low feathering susceptibility, and no visible fuzzing.

[0128] To assess abrasion resistance, each sample was tested using a Taber abrasion tester from Taber Indus (Tonnawanda, NY), which applies frictional abrasion to the sample using two abrasive wheels. Test samples were cut to 10×10 cm pieces and perforated to secure them to the machine, and 2000 Taber abrasion tester cycles were performed. Weight was measured before and after testing, and the percentage weight reduction was also measured. Three samples from several exemplary can-end blanks were tested, and the average weight reduction is reported in Table 3.

[0129] Table 3

[0130] sample Wear weight reduction (%) 5 0.07 7 0.09 A 0.18 B 0.23

[0131] The tested samples (samples 5 and 7) exhibited high abrasion resistance, especially compared to the comparison samples (samples A and B).

[0132] illustration

[0133] As used below, any reference to a series of examples should be understood as a reference to each of those examples individually (e.g., "examples 1 to 4" should be understood as "examples 1, 2, 3 or 4").

[0134] Example 1 is a process for preparing a can end blank, the process comprising: preheating a metal strip to a first temperature below 250°C; laminating a polymer film onto a first side of the metal strip to produce a laminated metal strip, wherein the first side of the metal strip corresponds to the outward-facing side of the can end formed by the metal strip; and annealing the laminated metal strip at an annealing temperature greater than 175°C.

[0135] Example 2 is the process of any of the foregoing or subsequent examples, wherein the metal strip is an aluminum strip.

[0136] Example 3 is the process of any of the foregoing or subsequent examples, wherein the polymer film comprises a polyethylene terephthalate film.

[0137] Example 4 is the process of any of the foregoing or subsequent examples, the process further comprising applying an adhesive coating to the metal strip, wherein pressing the polymer film layer to the first side of the metal strip comprises pressing the polymer film layer to the adhesive coating.

[0138] Example 5 is the process of any of the foregoing or subsequent examples, wherein the polymer film contains a colorant.

[0139] Example 6 is the process of any of the foregoing or subsequent examples, wherein the colorant is selected from the group consisting of carbon black and titanium dioxide.

[0140] Example 7 is the process of any of the foregoing or subsequent examples, the process of which further includes applying a paint layer to a second side of the metal strip, wherein the second side of the metal strip corresponds to the inward-facing side of the can end formed by the metal strip.

[0141] Example 8 is the process of any of the foregoing or subsequent examples, wherein the paint comprises an epoxy-based solution, a polyester solution, or a combination thereof.

[0142] Example 9 is the process of any of the foregoing or subsequent examples, wherein the annealing temperature is greater than 225°C.

[0143] Example 10 is the process of any of the foregoing or subsequent examples, wherein the annealing temperature is less than 300°C.

[0144] Example 11 is the process of any of the foregoing or subsequent examples, the process of which further includes cooling the laminated metal strip after annealing.

[0145] Example 12 is the process of any of the foregoing or subsequent examples, the process of which further includes applying a lubricant to the laminated metal strip after annealing.

[0146] Example 13 is a can-end blank product prepared according to the process of any of the foregoing examples.

[0147] Example 14 is a can end blank product of any of the foregoing or subsequent examples, wherein the first side of the metal strip corresponds to the outward-facing side of the can end blank product.

[0148] Example 15 is a can-end preform product of any of the foregoing or subsequent examples, wherein the polymer film has a thickness of less than 150 μm.

[0149] Example 16 is a beverage can comprising a can body and an end cap, wherein the end cap is formed from a can end blank prepared according to the process of any of the foregoing examples.

[0150] Example 17 is a system comprising: a preheating furnace for receiving a metal strip and preheating the metal strip to a preheating temperature; a lamination system positioned downstream of the preheating furnace for receiving the metal strip at the preheating temperature and applying a polymer film to a first side of the metal strip, wherein the first side of the metal strip corresponds to the outward-facing side of a can end formed by the metal strip; and an annealing furnace positioned downstream of the lamination system for receiving the laminated metal strip and heating the laminated metal strip at an annealing temperature greater than 200°C.

[0151] Example 18 is any system in the foregoing or subsequent examples, wherein the metal strip is an aluminum strip.

[0152] Example 19 is a system of any of the foregoing or subsequent examples, the system further comprising an adhesive coating application system for applying an adhesive coating to the metal strip, wherein the lamination system is configured to apply the polymer film to the adhesive coating.

[0153] Example 20 is any system illustrated in the foregoing or subsequent examples, wherein the lamination system is coupled to a polyethylene terephthalate film supply source.

[0154] Example 21 is a system of any of the foregoing or subsequent examples, the system further comprising a paint application system for applying a paint layer to a second side of the metal strip.

[0155] Example 22 is any system in the foregoing or subsequent examples, wherein the annealing temperature is greater than 225°C.

[0156] Example 23 is any system in the foregoing or subsequent examples, wherein the annealing temperature is less than 300°C.

Claims

1. A process for preparing can-end blanks, the process comprising: Preheat the metal strip to a first temperature below 250°C; A polymer film containing a colorant is laminated onto a first side of the metal strip to produce a laminated metal strip, wherein the first side of the metal strip corresponds to the outward-facing side of the can end formed by the metal strip, and the colorant is selected from the group consisting of carbon black and titanium dioxide. A paint layer is applied to a second side of the metal strip, wherein the second side of the metal strip corresponds to the inward-facing side of the can end formed by the metal strip, and the paint comprises an epoxy-based solution, a polyester solution, or a combination thereof; and The laminated metal strip is annealed at an annealing temperature greater than 175°C.

2. The process of claim 1, wherein the metal strip is an aluminum strip.

3. The process of claim 1, wherein the polymer membrane comprises a polyethylene terephthalate membrane.

4. The process of claim 1, further comprising applying an adhesive coating to the metal strip, wherein pressing the polymer film layer onto the first side of the metal strip comprises pressing the polymer film layer onto the adhesive coating.

5. The process as described in claim 1, wherein the annealing temperature is greater than 225°C.

6. The process of claim 1, wherein the annealing temperature is less than 300°C.

7. The process of claim 1, further comprising cooling the laminated metal strip after annealing it.

8. The process of claim 1, further comprising applying a lubricant to the laminated metal strip after annealing the laminated metal strip.

9. A can-end blank product prepared according to the process described in claim 1.

10. The can end blank product of claim 9, wherein the first side of the metal strip corresponds to the outward-facing side of the can end blank product.

11. The can-end preform product of claim 9, wherein the polymer film has a thickness of less than 150 μm.

12. A beverage can comprising a can body and an end cap, wherein the end cap is formed from a can end blank prepared according to the process of claim 1.

13. A system comprising: A preheating furnace, the preheating furnace being used to receive metal strips and preheat the metal strips to a preheating temperature; A lamination system, positioned downstream of the preheating furnace, is used to receive the metal strip at the preheating temperature and apply a polymer film to a first side of the metal strip, wherein the first side of the metal strip corresponds to the outward-facing side of the can end formed by the metal strip, wherein the polymer film contains a colorant selected from the group consisting of carbon black and titanium dioxide; A paint application system for applying a paint layer to a second side of the metal strip; wherein the paint comprises an epoxy-based solution, a polyester solution, or a combination thereof; as well as An annealing furnace, located downstream of the lamination system, for receiving and heating the laminated metal strips at an annealing temperature greater than 200°C.

14. The system of claim 13, wherein the metal strip is an aluminum strip.

15. The system of claim 13, further comprising an adhesive coating application system for applying an adhesive coating to the metal strip, wherein the lamination system is configured to apply the polymer film to the adhesive coating.

16. The system of claim 13, wherein the lamination system is coupled to a polyethylene terephthalate film supply source.

17. The system of claim 13, wherein the annealing temperature is greater than 225°C.

18. The system of claim 13, wherein the annealing temperature is less than 300°C.

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