In the pharmaceutical, cosmetics, food, and chemical industries, the choice of sealing material for small vials plays a decisive role in product quality, safety, and long-term stability. Coated aluminum sheet also known as lacquered aluminum sheet has become the mainstream material for vial sealing due to its excellent sealing performance, corrosion resistance, formability, and hygienic safety.

What Is a Coated Aluminum Sheet?

A coated aluminum sheet is produced through degreasing, chemical pretreatment, lacquer coating (clear/epoxy/acrylic), and oven curing.
The coating applied to the aluminum surface not only significantly enhances corrosion resistance but also improves appearance, increases compatibility with rubber liners, and ensures a smooth and safe opening experience.

8011 and 3105 aluminum alloys are the two most commonly used grades for small bottle seals. 8011 aluminum alloy has good formability and a high ear-making rate, making it suitable for deep drawing of long bottle caps. 3105 aluminum closure plates have excellent machinability and can guarantee the standard strength required for the product.

In addition, aluminum closure sheets often undergo chromate or DOS (dioctyl sebacate) surface treatment, which improves coating adhesion and further enhances corrosion protection.

Technical Specifications of Aluminum Sheets for Vial Sealing

Why Choose Coated Aluminum Sheet for Vial Sealing?

1. Corrosion Resistance: The 8011 and 3105 aluminum sheets undergo degreasing, chemical treatment, and baking curing, providing resistance to chemical corrosion. Whether it's acidic liquids, alcoholic reagents, or salt solutions, the small bottle sealing system maintains long-term stability.

2. Formability: The bottle cap aluminum sheets can be deep-drawn, rolled, and hook-rolled, maintaining high strength and shape accuracy after forming.

3. Superior Barrier Properties: Aluminum itself has excellent light, oxygen, and moisture barrier properties, providing the strongest protection for not only small-volume but also often high-value contents (such as antibiotics, essential oils, and premium spirits).

4. Ease of Opening and Security: The aluminum cap has a stable torsional torque, ensuring both tightness and ease of opening for consumers (e.g., ROPP tamper-evident caps).

5. High Temperature Resistance: Resistant to pasteurization, high-temperature sterilization, and other high-temperature processes.

6. Lightweight and Low-Cost: Aluminum has only one-third the density of steel, reducing transportation weight while maintaining sufficient strength. It's ideal for sealing small bottles, ensuring performance while reducing costs.

7. Aesthetics and Brand Enhancement: Painted aluminum sheets have a smooth, glossy surface, supporting multi-color printing and significantly enhancing the product's shelf image.

8. Environmentally Friendly: Aluminum is 100% recyclable, producing no harmful residues.

Application Fields

• Pharmaceutical Packaging: 10ml/20ml oral liquid puncture-resistant aluminum caps, vials with aluminum-plastic composite caps (requires non-toxicity and high-temperature resistance).

• High-end Alcoholic Beverages: 50ml mini bottle caps, whiskey/vodka tamper-evident long-necked caps (requires good deep-drawing performance and exquisite printing).

• Cosmetics and Health Products: Essential oil dropper aluminum rings, collagen drink bottle caps, bird's nest bottle sealing caps.

How to Select High-Quality Aluminum Sheets for Vial Caps?

1. Extremely Low Earing Rate

Small bottle caps have small diameters. If the material has high anisotropy during stamping, noticeable "ears" (uneven edges) can appear on the edges. High-quality 8011/3105 painted aluminum sheets, through a rigorous heat treatment process, control the earing rate to an extremely low level, ensuring a smooth and aesthetically pleasing seal edge and significantly improving material utilization.

2. Food-Grade Coating Safety

Inner Coating: Typically uses epoxy resin or polypropylene (PP) coating. It must be FDA and SGS certified to ensure acid and alkali resistance, and will not peel off after high-temperature cooking or react with pharmaceuticals/foods.

Outer Coating: Uses polyester or acrylic topcoat, with vibrant colors and scratch resistance, providing a perfect base for subsequent offset or pad printing.

3. Strict Thickness and Shape Control

Small bottle sealing often involves high-speed automated capping machines. The thickness tolerance of aluminum plates usually needs to be controlled within ±0.005mm, and the plate surface must be flat and free of oil spots (DOS oil treatment must be uniform) in order to ensure that there is no jamming or cap jumping on the high-speed production line with hundreds of pieces per minute.