CRAZING RESISTANT CAN END STOCK
Provided herein are an aluminum can end stock (CES) and methods for producing CES. The CES includes a laminated metal strip having a polymer film coating and beneficially exhibiting crazing resistance. In some cases, the crazing-resistant CES described herein also exhibit low feathering and high abrasion resistance. The laminated metal strip can include the laminated polymer coating on an interior-facing side of the metal strip. The laminated metal strip can further include a pretreatment coating between the polymer film coating and the metal strip. The CES is formed by laminating a polymer film to a side of the metal strip and annealing the laminated metal strip. In some cases, the polymer film laminated to the metal strip is a polyethylene terephthalate (PET) film.
1 . A process for preparing a crazing-resistant can end stock, comprising:
applying a pretreatment coating to a first side of a metal strip;
laminating a polymer film to the first side of the metal strip to form a laminated metal strip, wherein the polymer film is adhered to at least a portion of the pretreatment coating; and
annealing the laminated metal strip at an annealing temperature, wherein the annealing temperature is less than 250° C.
2 . The process of claim 1 , wherein the can end stock exhibits no visible crazing.
3 . The process of claim 1 , wherein the first side of the metal strip corresponds to an interior-facing side of a can end formed from the metal strip.
4 . The process of claim 1 , wherein the metal strip is an aluminum strip.
5 . The process of claim 1 , wherein the polymer film comprises a polyethylene terephthalate film.
6 . The process of claim 1 , wherein the pretreatment coating comprises a polymer or co-polymer.
7 . The process of claim 1 , wherein the annealing temperatures is less than 230° C.
8 . The process of claim 1 , wherein the annealing temperature is greater than 150° C.
9 - 12 . (canceled)
13 . A can end stock, comprising:
a metal strip;
a pretreatment composition; and
a polymer film,
wherein the can end stock exhibits no visible crazing.
14 . The can end stock of claim 13 , wherein the can end stock exhibits no visible crazing within 24 hours after a strain test, wherein the strain test comprises application of a 2% strain with a 10 N/mm 2 ·s force.
15 . The can end stock of claim 13 , wherein the can end stock exhibits no visible crazing under UV light within 24 hours after the strain test, wherein the strain test further comprises coating the samples with a fluorescent marker.
16 . The can end stock of claim 13 , wherein the metal strip is an aluminum strip.
17 . The can end stock of claim 13 , wherein the polymer film comprises a polyethylene terephthalate.
18 . The can end stock of claim 13 , wherein the pretreatment composition is a polymer or co-polymer.
19 . The can end stock of claim 13 , wherein the polymer film exhibits an FTIR absorbance peak intensity ratio (A/B) greater than 0.4, wherein A indicates a first absorbance peak at a wavenumber from 1330 cm −1 to 1350 cm −1 and B indicates a second absorbance peak at a wavenumber from 1400 cm −1 to 1420 cm −1 .
20 . The can end stock of claim 13 , wherein the absorbance peak intensity ratio (A/B) is greater than 1.0.
21 . A system, comprising:
a lamination system for accepting a metal strip and applying a polymer film to a first side of the metal strip; and
an annealing furnace positioned downstream of the lamination system for accepting a laminated metal strip and heating the laminated metal strip at an annealing temperature, wherein the annealing temperature is less than 250° C.
22 . The system of claim 21 , wherein the metal strip is an aluminum strip.
23 . The system of claim 21 , further comprising a pretreatment coating application system for applying a pretreatment coating to the metal strip, wherein the lamination system is configured to apply the polymer film to the pretreatment coating.
24 . The system of claim 21 , wherein the lamination system is coupled to a supply of polyethylene terephthalate film.
25 - 30 . (canceled)