What is a 31.5x24 mm ROPP Aluminum Cap?
“31.5x24 mm” indicates a cap diameter of 31.5 mm and a height of 24 mm. “ROPP” stands for Roll-On Pilfer-Proof, describing an aluminum cap that is mechanically roll-formed onto the bottle neck for a precise, tamper-evident, leak-proof seal.
ROPP Technology: Dual Protection for Safety and Freshness
ROPP closures are an outstanding application of modern packaging technology. They’re more than simple screw caps—they feature an ingenious tamper-evident design:
Custom-Formed Threads:
Unlike pre-threaded caps, ROPP caps are roll-formed on the bottling line. Specialized capping equipment presses the aluminum cap onto the bottle neck, creating perfectly matched threads on-site. This “tailored fit” delivers superior sealing performance.Tamper-Evident Band:
A distinctive tear-off band at the cap’s base breaks automatically upon first opening and remains on the bottle neck. This clearly indicates the product is being opened for the first time, preventing tampering or refilling before sale, and boosting consumer confidence.
Olive Oil-Specific Liners and Pourers
A high-quality olive oil aluminum cap is about more than just size and material—it’s also about its internal structure:
Specialized Liners:
The inside typically contains a dedicated liner made of non-toxic, oil-resistant, and chemically inert materials (such as specific grades of polyethylene or butyl rubber). These ensure no chemical reaction with olive oil, preserving its quality and preventing off-flavors.Pourer Inserts:
Premium olive oil caps often integrate a plastic pourer. This insert helps consumers precisely control the flow of oil, avoiding splashing or drips down the bottle, enhancing user experience.
31.5x24 mm ROPP Aluminum Closure Specifications
| Size | 31.5 × 24 mm |
| Material | Aluminum 8011 |
| Color | Standard gold, silver, or custom colors |
| Liner Options | PE liners, disc liners, aluminum foil liners, etc. |
| Printing Options | Side printing, hot stamping (gold/silver), silk screen, embossing, QR codes, etc. |
| Design | Tamper-evident roll-on closure |
| Applications | Designed for olive oil, mineral water, or beverage glass and plastic bottles |
| Lead Time | Standard caps 15–20 days |
| Packaging | Carton + pallet |
| MOQ | 100,000 pcs |
Why Choose a 31.5 mm Cap for Olive Oil Packaging?
1. Excellent Sealing and Freshness Preservation
Olive oil is highly sensitive to light, air, and humidity, making it prone to oxidation and spoilage if poorly packaged. 31.5x24 mm ROPP aluminum caps typically use food-grade EPE liners or PVDC coatings to create an effective barrier against air and moisture, extending shelf life.
2. Tamper-Evident Structure Enhances Brand Trust
The cap’s breakaway band irreversibly indicates first opening, assuring consumers the product is factory-sealed and original. This helps protect against counterfeiting and builds brand reputation.
3. Lightweight and Eco-Friendly, Ideal for Sustainable Packaging
Aluminum is 100% recyclable, making it a greener choice than plastic caps. It is also lightweight, reducing shipping costs and improving transport efficiency.
4. High-Precision Printing and Customization
ROPP aluminum caps support multiple printing methods (offset, screen, hot-stamping, etc.). Brands can customize logos, graphics, and security codes, turning every cap into a promotional medium.
5. Compatible with Various Bottle Types and Filling Lines
The 31.5x24 mm cap is widely used with standard glass or PET bottles. It suits automated filling lines well, ensuring high capping consistency, speed, and low wastage.
ROPP Cap Manufacturer – HAOMEI Aluminum
Customization Options
Supports various surface finishing techniques: offset printing, embossing, UV inkjet coding, hot stamping, silk screen printing, etc.
Custom logos, QR codes, or security codes available (requires advance design files). Perfect for brand protection and traceability.
Production and Supply Details
Minimum Order Quantity (MOQ):
Standard orders start at 100,000 pcs. Mixed colors or styles supported.
Delivery and Logistics:
In-stock orders: Ship within 7 days.
Custom orders: Approx. 1 month production cycle (expedited production negotiable).
Packaging: Standard export cartons (custom inner partitions or reinforcements available).
Certification and Quality Control:
ISO/SGS food safety certified.
Compliant with food-contact material standards.
Fully automated production-line inspection to ensure sealing integrity and dimensional precision.
