HSL Coated Aluminium Foil For Blister Pack

HSL coated aluminium foil is a high-performance composite material and is heat-sealed in blister packaging to achieve a strong bond to the plastic substrate. Heat seal lacquer (HSL) is applied to the aluminum foil surface, achieving a reliable seal with plastic substrates while maintaining the aluminium foil’s high barrier properties and mechanical strength. Its barrier properties, sealability, and processability make it a core packaging material for pharmaceuticals, food and other applications.

Structural Composition of HSL Coated Aluminium Foil:

HSL coated aluminum foil typically utilizes a multi-layer composite structure, for example:

– Aluminum foil substrate:

8011 aluminum foil with a purity of ≥99.9% and a thickness ranging from 20-30μm, providing excellent barrier properties (light blocking rate >99.9%) and mechanical strength.

– Heat seal coating (HSL):

Mainly composed of solvent-based vinyl/acrylic resin or water-based acrylic emulsion, with a thickness of 3-8g/m², it ensures a strong heat seal with plastic substrates such as PVC and PVDC while meeting non-toxic and solvent-resistant requirements. Water-based coatings can reduce VOC emissions by over 90%, aligning with environmental trends.

– Printing Primer (OP): Used to improve the surface tension of aluminum foil (typically treated to 38-42 dynes), enhance ink adhesion, and support multi-color printing with UV and water-based inks.

Technical Parameters of HSL Coated Aluminium Foil:

1. Heat Seal Performance:

– Temperature Range: Conventional heat sealing temperature is 210-220°C. Low-melting-point coatings (e.g., 65°C) are suitable for heat-sensitive products.

– Seal Strength: ≥8N/15mm (Asian standard) or ≥12N/15mm (European standard), ensuring package integrity.

– Hot Tack: Provides instant seal strength even before complete cooling, preventing bag breakage on high-speed production lines.

2. Barrier Performance:

– Water Vapor Transmission Rate (WVTR): ≤0.5g/(m²/24h)

– Oxygen Transmission Rate (OTR): ≤0.5cm³/(m²/24h/0.1MPa), far exceeding pharmaceutical packaging requirements (e.g., vaccines require a WVTR ≤0.002g/(m²/24h)).

3. Mechanical Properties:

– Hardness: Made of hard anodized aluminum, it easily opens with a push-through mechanism, with a rupture force within a range of 5-15N.

– Flexibility: Adapts to the tensile deformation during blister molding without cracking or coating delamination.

4. Safety and Compliance:

– Certifications: FDA 21CFR 175.300 and EU EC 10/2011 food contact certifications are met. Pharmaceutical-grade products must comply with China’s NMPA standards and ISO 15378 medical device packaging requirements.

– Migration Testing: Heavy metal (Pb, Cd, As) migration is ≤ 0.1mg/kg, ensuring drug compatibility.

Performance Advantages of HSL Coated Aluminium Foil In Blister Packaging:

– Barrier Properties: Aluminum foil possesses excellent barrier properties, effectively blocking light, oxygen, water vapor, and odors, extending the shelf life of the contents.

– Sealing: The HSL coating provides a strong heat-seal strength with the plastic substrate, forming a secure seal after heating, preventing the ingress of moisture and oxygen, and preventing contents from leaking or becoming damp.

– Corrosion Resistance: The HSL coating improves the corrosion resistance of the aluminum foil, adapting to various packaging environments and ensuring it remains intact during transportation and storage.

– Printability: HSL coated aluminium foil allows for high-quality printing, facilitating branding and product information display.

– Processing Compatibility: It supports high-speed automated packaging lines and is compatible with processes such as compression molding and blister molding.

– Safety: The coating material must meet food/drug contact standards, ensuring no migration or odor.

– Environmental Protection: The aluminum foil is recyclable, meeting current environmental requirements.

Applications of HSL Coated Aluminum Foil in Blister Packaging

– Pharmaceutical Packaging

Tablets and Capsules: HSL-coated aluminum foil is laminated with PVC rigid sheet to form individual blisters, protecting the drug from contamination and mechanical damage.

High Barrier Requirements: When used in conjunction with a PVDC composite substrate, it is suitable for oxygen-sensitive drugs (such as antibiotics and vitamins).

– Food Packaging

Candy and chocolate: HSL-coated aluminum foil provides moisture and oxidation protection while supporting easy-tear designs for an enhanced user experience.

Functional foods, such as probiotics and dietary supplements, require the barrier of aluminum foil to maintain their long-term activity.

HSL coated aluminium foil, due to its excellent heat-sealing properties, high barrier properties, and regulatory compliance, has become the preferred material for blister packaging.