The 31.5x44mm aluminum cap is a high-performance sealing component specially designed for glass bottle packaging.
This cap provides sufficient decorative space and rolling distance for long-neck glass bottles, making it widely used in premium wine, spirits, extra virgin olive oil, high-value cosmetics, and pharmaceutical products.
The 31.5*44mm aluminum ROPP cap is typically equipped with a dedicated sealing liner, ensuring a perfect fit with the bottle mouth and forming an airtight barrier for complete product protection.
Liner Options for 31.5x44mm Aluminum Bottle Caps
| Liner Material | Suitable Contents | Technical Advantages |
| PE Foam (Polyethylene Foam) | General liquids, cosmetics | Cost-effective with good overall sealing performance. |
| Saranex | Wine, spirits | High oxygen barrier, effectively prevents oxidation and preserves product flavor. |
| PVC | Carbonated beverages (specific design) | Excellent gas retention; suitable for pressurized products when paired with compatible bottle necks. |
Printing and Decoration
Printing & Decoration: Offset printing, screen printing, and hot stamping can be applied to create multi-color designs, brand logos, and anti-counterfeiting marks.
Embossing / Debossing: Custom molds can create raised or recessed graphics or lettering on the top surface, enhancing brand presence and tamper-proof characteristics.
Performance Advantages of the 31.5×44mm Aluminum ROPP Cap
1. Protection Performance
Aluminum offers complete light blocking, effectively protecting light-sensitive contents (such as beer and pharmaceuticals) from UV degradation.
Its excellent gas barrier prevents oxygen and other gases from penetrating, maintaining product freshness and extending shelf life.
2. Mechanical Performance
Aluminum possesses high strength and rigidity, capable of withstanding the mechanical stress during bottling and transport.
It also has superior ductility, making it ideal for high-speed stamping and rolling processes to achieve complex shapes in a single forming cycle.
3. Lightweight Design
Compared with other metal closures, aluminum is significantly lighter, reducing packaging weight, logistics costs, and carbon emissions.
4. Safety and Hygiene
Aluminum meets both food-grade and pharmaceutical packaging standards, ensuring it will not react with the contents or cause contamination.
Its tamper-evident design provides an additional layer of product safety - consumers can easily verify product integrity by checking the unbroken closure ring.
5. Aesthetic Appearance
Multiple surface finishes are available, including glossy, matte, electroplated, printed, or hot-stamped effects, to achieve an elegant and premium appearance.
Technical Specifications of the 31.5×44mm Aluminum ROPP Cap
| Outer Diameter | 31.5 mm |
| Height | 44 mm |
| Material Thickness | 0.21-0.23 mm |
| Material Alloy | AA8011 / AA3105 / AA5052 aluminum alloy |
| Coating Type | Epoxy resin / BPA-free coating |
| Color Options | Silver, gold, red, black, blue – customizable |
| Neck Finish Type | Tamper-evident |
| Printing | Top and side offset printing, multicolor available |
| Surface Finish | Glossy / satin / matte |
| Processes | Flat printing, side offset printing, knurling, bridging, top embossing (with color). All paints, inks, and liners used are FDA approved. |
| Feature | Pilfer-proof |
| Type | Screw cap (ROPP) |
| Sample | Available |
| Packaging | Standard export carton/pallet or customized packaging |
| Application | Wine, spirits, whiskey, beverages, olive oil |
| MOQ | 80,000 pcs |
Application Fields
1. Beverage Industry
In high-end beer, carbonated drink, and functional beverage packaging, aluminum caps provide reliable sealing performance and an excellent platform for brand presentation.
Their light-blocking and gas-tight properties help preserve the original flavor and stability of beverages.
2. Food Industry
Used for sauces, condiments, and premium food packaging, the aluminum cap helps maintain product freshness and flavor, extending shelf life.
3. Pharmaceutical and Cosmetic Industry
The pharmaceutical sector values aluminum caps for their hygiene, safety, and protective features.
In cosmetics, aluminum closures add elegance and high-end visual appeal, while ensuring excellent product protection.
Key Quality Control Indicators (QC)
| Parameter | Description |
| Opening Torque | Maintained between 1.0 N·m - 2.5 N·m for easy consumer opening while ensuring airtight sealing. |
| Pressure Resistance | Capable of withstanding internal pressure, critical for carbonated or pressurized products. |
| Sealing Performance | Verified by vacuum retention and leakage testing to ensure airtightness. |
| Tamper Ring Separation | The pilfer ring must break cleanly without burrs or residual connections. |
| Coating Adhesion | Ensures printed and coated surfaces remain intact after the rolling and capping process. |
