Cold rolled strip for double zero aluminum foil
Cold-rolled strip for double-zero aluminum foil is a specialized raw material for producing aluminum foil with a thickness of ≤ 0.01mm (“double-zero” refers to two decimal places with zeros when expressed in millimeters). Featuring extremely high purity, uniform microstructure, and excellent plasticity, it is a high-end product in the aluminum processing industry and widely used in food packaging, pharmaceutical packaging, and electronic devices. Its primary materials are aluminum alloys such as 1235 and 8011. 1235 aluminum foil strip has a purity of ≥99.35%, a high aluminum content, and low impurities, making it suitable for producing extremely thin foil. 8011 aluminum foil strip, with a manganese content of 0.8%-1.3% and an iron content of 0.6%-1.0%, offers increased strength and is suitable for packaging applications requiring a certain degree of stiffness. Cold-rolled strip typically has a thickness of 0.3-0.6mm and a width of up to 1800mm. Its surface finish Ra is ≤ 0.1μm, and its flatness deviation is ≤ 2I, providing high-quality stock for subsequent foil rolling.
The production process of cold-rolled strip for double-zero aluminum foil is a delicate one, requiring constant control of purity and uniformity. First, aluminum ingots with a purity of at least 99.7% are melted in a furnace at a controlled temperature of 720-740°C. Hydrogen (≤ 0.15ml/100gAl) and inclusions (≤ 10μm) are removed through an online degassing and filtration system. The melt is then continuously cast and rolled into cast-rolled coils with a thickness of 6-8mm at a speed of 1.2-1.8m/min to ensure uniform grain size (average grain size ≤ 50μm). Subsequently, the coil undergoes multiple cold rolling passes, gradually reducing the thickness to 0.8-1.2mm, with a reduction of 20%-30% per pass. Annealing treatment (350-400°C for 4-6 hours) is performed to eliminate work hardening. The finishing stage utilizes a 24-high cold rolling mill, rolling the strip to a thickness of 0.3-0.6mm at a rolling speed of 60-100m/min. The tension is controlled to maintain a stable ±5% to ensure flatness. Finally, degreasing and cleaning (oil film ≤ 3mg/m²) and annealing (300-330°C) are performed to achieve an elongation of ≥30%. Microstructure testing (for the absence of segregation and inclusions) and surface quality inspection ensure compliance with the requirements for double-zero aluminum foil rolling.
In the food packaging sector, cold-rolled strip for double-zero aluminum foil is a core raw material for aseptic packaging. Aluminum foil for powdered foods like milk powder and coffee is made from 1235 cold-rolled strip, with a thickness of only 0.006-0.008mm . It offers excellent barrier properties (oxygen transmission rate ≤ 0.1cm³/m² / day ). A certain milk powder brand’s shelf life has been extended to 24 months using this foil . Chocolate and candy packaging uses 8011 cold-rolled strip, rolled into 0.009-0.01mm thick foil. This foil offers both flexibility and stiffness, resisting cracking when folded. This has helped one chocolate manufacturer reduce packaging waste by 15% . In the convenience food sector, the aluminum foil layer of retort pouches uses double-zero aluminum foil, which can withstand sterilization at temperatures up to 121 °C. The foil used for a certain brand of self-heating rice has been tested for 1,000 flex cycles without breaking.
The pharmaceutical packaging and electronics sectors demand extremely high purity from cold-rolled strip for double-zero aluminum foil. Tablet and capsule blister packaging aluminum foil uses 1235 cold-rolled strip, rolled to a thickness of 0.007-0.009mm. After a surface coating treatment, it possesses excellent corrosion resistance and sealing properties. This has resulted in a pharmaceutical company’s blister packaging aluminum foil pass rate reaching 99.8%. Infusion bag aluminum foil covers use 8011 cold-rolled strip, rolled to a thickness of 0.01mm. Its excellent puncture resistance ensures smooth needle insertion, while its sealing properties prevent contamination of medications. A medical device manufacturer has achieved a 100% pass rate for these aluminum foil covers. In the electronics sector, capacitor electrode aluminum foil uses ultra-high-purity cold-rolled strip (99.9% aluminum content), rolled to a thickness of 0.005mm, and then treated with corrosion treatment. This increases the specific surface area by over 100 times, increasing the capacitor capacity of an electronic component manufacturer by 30%.
With the advancement of the packaging industry and the miniaturization of electronic devices, the performance of cold-rolled strip for double-zero aluminum foil continues to break through. Manufacturers have developed ultra-thin cold-rolled strip (0.2-0.3mm thick), which can be rolled into 0.004mm aluminum foil for high-end electronic packaging, increasing material utilization by 20%. To address environmental concerns, a biodegradable coated cold-rolled strip has been developed. The coating naturally degrades after the foil is discarded, reducing environmental pollution. A European packaging company has already adopted this product in large quantities. In terms of process innovation, asynchronous rolling technology is used to maintain a thickness tolerance of ±0.002mm for cold-rolled strip, ensuring stable production of double-zero aluminum foil. In the future, with the development of new energy batteries and flexible electronics, cold-rolled strip for double-zero aluminum foil will move towards higher purity and thinner gauges, and its application areas will continue to expand.
