Analysis on Multi-Dosage Form Adaptability and Full-Dimensional Barrier Protection Performance of 8011 aluminum alloy foil for pharmaceutical packaging

HW-A. Introduction: Core Requirements of Pharmaceutical Packaging Substrates and Positioning of 8011 Alloy Aluminum Foil

Pharmaceutical packaging serves as the “last line of defense” for ensuring drug quality. Its substrate must meet three core requirements: dosage form adaptability (adapting to packaging processes and usage scenarios of different drug forms), full-dimensional barrier property (resisting external environmental erosion on drugs), and compliance (meeting pharmaceutical-grade material safety standards). Among various pharmaceutical packaging substrates, 8011 alloy aluminum foil stands out as a top choice for domestic and international pharmaceutical companies, thanks to its excellent mechanical properties, chemical stability, and processability.
8011 alloy belongs to the Al-Fe-Si series non-heat-treatable aluminum alloy, with chemical composition complying with GB/T 3198-2020 (Aluminum and Aluminum Alloy Foils): Fe content (0.7%-1.1%), Si content (0.5%-0.9%), Cu content ≤0.1%, and Mn content ≤0.1%. This composition enhances the tensile strength and puncture resistance of the aluminum foil through solid solution strengthening, while retaining an elongation of 25%-30% (annealed state, tested per GB/T 228.1-2021). Through multi-pass cold rolling (cold rolling reduction rate ≥90%) and continuous annealing (annealing temperature 320-360°C), it can be processed into ultra-thin foil with a thickness of 0.015mm-0.05mm, meeting the lightweight and precision requirements of pharmaceutical packaging. Additionally, after chromate passivation (passivation film thickness 50-80nm, complying with YBB 00352004-2015), the heavy metal (Pb, Cd, Hg, As) migration of 8011 alloy aluminum foil is ≤0.1μg/g, which meets standards like YBB 00152002-2015 (Pharmaceutical Aluminum Foil) and provides a foundation for drug safety.

HW-B. Analysis on Multi-Dosage Form Adaptability of 8011 Alloy Aluminum Foil

The diversity of drug dosage forms (solid preparations, liquid preparations, semi-solid preparations, special dosage forms, etc.) imposes differentiated requirements on the morphology, mechanical properties, and processing technology of packaging substrates. 8011 alloy aluminum foil can cover the packaging needs of mainstream pharmaceutical dosage forms through performance adjustment and process adaptation. The table below summarizes its adaptive indicators for different dosage forms:

Table 1 Core Adaptive Parameters of 8011 Alloy Aluminum Foil for Multi-Dosage Form Packaging

A. Solid Preparations: Core Substrate for Blister Packaging and Aluminum-Plastic Composite Films

Solid preparations account for over 60% of the pharmaceutical market, and their packaging core needs focus on “high-precision formability + long-term sealing”. 8011 alloy aluminum foil achieves performance adaptation through process adjustment:

• PTP blister packaging: Uses 8011 aluminum foil in O state (fully annealed) with a thickness of 0.02-0.025mm. Multi-pass cold rolling ensures a thickness deviation of ≤±5% (GB/T 3198). During stamping, it can achieve a deep drawing depth of 3-5mm without cracking. When matched with the heat-sealing temperature (120-140°C) of PVC/PE substrates, it forms a sealed cavity with an oxygen concentration ≤0.5% (long-term storage), effectively inhibiting tablet hydrolysis and capsule softening.

• Aluminum-plastic composite film packaging: For moisture-sensitive granules, corona-treated 8011 aluminum foil (surface tension ≥38dyn/cm) is compounded with low-density polyethylene (LDPE) via polyurethane adhesive. The peel strength reaches ≥3N/15mm (YBB 00072004), enabling adaptation to high-speed packaging lines (150-200 packs/min) while meeting the usability requirement of “tear force ≤10N” (GB/T 27728).

B. Liquid Preparations: Chemical Resistance Adaptation for Bagged Packaging and Bottle Stopper Gaskets

Liquid preparations have strict requirements for “chemical inertness + sterile barrier” of packaging. 8011 alloy aluminum foil achieves adaptation through material compounding and state adjustment:

• Composite flexible bags for oral solutions: Adopts a three-layer structure (PET/Al/PE), where 8011 aluminum foil has a thickness of 0.03-0.04mm and undergoes double-sided chromate passivation (passivation film impedance ≥1000Ω). After sterilization at 121℃/30min, its adsorption rate for organic acids (e.g., citric acid) and alkaloids (e.g., ephedrine) is ≤0.1% (USP <1086), with no leachables detected in the 72h immersion test (YBB 00142002).

• Bottle stopper gaskets for injections: Uses 8011 aluminum foil in H12 state (partially annealed) with Vickers hardness controlled at HV 25-30. It is thermocompressed with halogenated butyl rubber, resulting in a puncture debris rate ≤0.1% (far lower than the 0.5% specified in YBB 00332004). The sealing retention rate after puncture exceeds ≥99% (pressure decay test, ISO 11607-2), avoiding particulate contamination and microbial invasion of liquids.

C. Semi-Solid Preparations and Special Dosage Forms: Process Adaptation for Hoses and Aerosols

Semi-solid preparations (ointments, creams) and special dosage forms (aerosols, patches) require higher “mechanical tolerance + functional adaptability” of packaging. 8011 alloy aluminum foil achieves precise matching through thickness and state optimization:

• Aluminum-plastic hoses for ointments: Uses 8011 aluminum foil in H18 state (cold-rolled hardened) with a thickness of 0.025-0.03mm and tensile strength ≥110MPa. It shows no cracks after 180° bending (mandrel diameter = aluminum foil thickness, GB/T 22639). When compounded with the inner PE layer, it exhibits excellent swelling resistance to ointment bases (e.g., petrolatum, lanolin) and no delamination after 12 months of storage at 25℃.

• Composite aerosol cans: 8011 aluminum foil (thickness 0.035-0.045mm) forms a cylindrical can body via laser welding. When matched with tinplate bottom lids, it achieves a burst pressure ≥1.5MPa (ISO 11602) and can withstand long-term internal pressure (0.8-1.2MPa at 25℃) from propellants (e.g., dimethyl ether, propane). The leakage rate at welds is ≤1×10⁻⁶Pa·m³/s (helium mass spectrometry leak detection).

HW-C. Analysis on Full-Dimensional Barrier Protection Performance of 8011 Alloy Aluminum Foil

The main causes of drug deterioration include oxygen, water vapor, light, microorganisms, and volatile substances in the external environment. Relying on its close-packed hexagonal metal crystal structure, 8011 alloy aluminum foil builds a “full-dimensional barrier”. Its protection performance is analyzed based on key influencing factors:

A .Oxygen Barrier: Zero-Permeation Characteristics of Dense Metal Structure

Oxygen is the primary factor causing drug oxidative degradation (e.g., vitamin C dehydrogenation, β-lactam antibiotic ring opening). For 8011 alloy aluminum foil, the oxygen transmission rate (OTR) meets GB/T 1038-2022, measuring ≤0.1cm³/(m²·24h·atm) at 23℃ and 50% RH—far lower than that of pharmaceutical PE (OTR≈500cm³/(m²·24h·atm)) and EVOH (OTR≈5cm³/(m²·24h·atm)). The barrier mechanism lies in the dense, pore-free crystal structure formed by closely arranged aluminum atoms. The activation energy for oxygen molecule diffusion exceeds ≥80kJ/mol (much higher than 20-40kJ/mol of polymer substrates), preventing penetration via molecular diffusion. Even during a 2-year shelf life, the oxygen concentration inside the packaging can remain ≤0.5% (headspace gas chromatography, GB/T 28765), effectively delaying drug oxidative degradation.

B. Water Vapor Barrier: Hydrophobic Enhancement of Passivation Film

Water vapor causes moisture absorption and caking of solid preparations (e.g., aspirin hydrolysis, cephalosporin granule deliquescence) and concentration changes of liquid preparations. The water vapor transmission rate (WVTR) of 8011 alloy aluminum foil meets GB/T 1037-2021, measuring ≤0.1g/(m²·24h) at 38℃ and 90% RH—1/500 to 1/1000 that of pharmaceutical PE. Chromate passivation forms a dense Cr₂O₃·nH₂O oxide film on the aluminum foil surface, with a contact angle ≥90° (hydrophobic property, GB/T 30693), significantly reducing the affinity between water molecules and the foil surface. Even in humid environments (e.g., rainy seasons in southern China), the relative humidity inside the packaging can be controlled ≤30% (GB/T 11793), avoiding drug deterioration due to moisture absorption.

C. Light Barrier: Opaque Light Shielding Effect

Some drugs (e.g., vitamin B2, nitroglycerin, nifedipine) are sensitive to 200-400nm ultraviolet light and 400-800nm visible light, prone to photolysis. The optical density (OD value) of 8011 alloy aluminum foil meets YBB 00122003, reaching ≥6.0 (completely opaque), which blocks 100% of light in the 200-800nm wavelength range. This outperforms PP with light blockers (OD≈3.0) or brown glass (OD≈4.5) in light shielding. In practical applications, nitroglycerin tablets packaged in PTP blisters with 8011 aluminum foil show a photolysis rate ≤0.5% after 10 days of exposure to 4500lx light—far lower than the 15% of brown glass bottle packaging (HPLC method, USP <1191>).

D. Microbial and Chemical Barrier: Sterile Barrier and Inertness

• Microbial barrier: 8011 alloy aluminum foil has no biological activity. After sterilization with saturated steam at 121℃ for 30min (ISO 11134), the microbial residue is ≤1CFU/100cm² (YBB 00012003). When combined with heat-sealing structures, it forms a “sterile barrier system” meeting ISO 11607-1, with a microbial invasion rate ≤0.01% (accelerated aging test: 40℃, 75% RH for 6 months). It is suitable for packaging sterile preparations such as injections and sterile powder injections.

• Chemical barrier: The chemical stability of 8011 alloy aluminum foil meets YBB 00152002-2015, showing no corrosion in the pH range of 1-12 and no chemical reactions with common drug components (acids, alkalis, organic solvents, surfactants). The migration of heavy metals (Pb, Cd, Hg, As) is ≤0.1μg/g, and the migration of substances (volatile organics, plasticizers) is ≤0.5mg/dm² (YBB 00312004), avoiding chemical migration impacts on drug purity.

HW-D. Performance Optimization and Practical Application Cases

A .Performance Optimization: Composite Technology and Surface Modification

To expand application scenarios, 8011 alloy aluminum foil often enhances comprehensive performance through composite technology and surface modification. Typical optimization solutions include:

1. Multi-layer composite structure optimization:

• • Injection flexible bags: Adopt a three-layer structure of “PET (12μm)-Al (35μm, 8011 alloy)-PE (50μm)”. The PET layer improves puncture resistance (puncture force ≥30N, YBB 00212004), the PE layer provides heat-sealing properties, and the 8011 aluminum foil ensures barrier performance. It can withstand freezing storage at -40℃ and sterilization at 121℃.

• • Pharmaceutical aluminum-paper composite films: Use a structure of “paper (60g/m²)-Al (20μm, 8011 alloy)-PE (30μm)”. The paper layer improves printability (ink adhesion ≥95%, GB/T 1720), and the Al layer ensures barrier performance. It is suitable for tablet outer packaging boxes, balancing aesthetics and protection.

2. Surface modification technology:

• • Chromium-free passivation: Uses zirconate passivation (ZrO₂ film thickness 30-50nm) instead of traditional chromate passivation, meeting the EU REACH regulation (restricting hexavalent chromium use) while maintaining WVTR ≤0.15g/(m²·24h), aligning with environmental trends.

• • Antibacterial coating: Coats the aluminum foil surface with a nano-silver antibacterial layer (thickness 10-20nm), achieving an antibacterial rate ≥99% (GB/T 21866). It is suitable for packaging mucosal preparations (e.g., ointments, patches) to reduce microbial contamination risks.

B.Application Case: Packaging Upgrade for Amoxicillin Capsules in a Large Pharmaceutical Enterprise

A domestic antibiotic manufacturer (annual production capacity: 5 billion capsules) upgraded the packaging of amoxicillin capsules from 1235 alloy aluminum foil (traditional substrate) to 8011 alloy aluminum foil. The specific application parameters and effects are as follows:

• Aluminum foil parameters: Thickness 0.022mm (O state), elongation 28%, surface tension 40dyn/cm, chromate passivation.

• Packaging form: PTP blister (PVC substrate thickness 0.25mm), heat-sealing temperature 130℃, heat-sealing time 0.5s.

• Performance improvements:

1. 1. Forming qualification rate: Increased from 95% to 99.5%, reducing annual packaging loss by 225 million capsules (based on 5 billion capsules of annual capacity).

1. 2. Stability: In the accelerated test (40℃, 75% RH for 6 months), the dissolution rate change of capsules decreased from 3% to 0.8% (HPLC method, USP <711>), and the content of oxidative degradation product (amoxicillin thiazole acid) was ≤0.1% (far below the pharmacopoeia limit of 0.5%).

1. 3. Cost optimization: The processing efficiency of 8011 alloy aluminum foil increased by 15% (cold rolling speed from 600m/min to 690m/min), reducing the comprehensive packaging cost by 8% and saving approximately 1.2 million yuan annually.

This case verifies the dual advantages of 8011 alloy aluminum foil in “performance improvement + cost optimization”. Currently, it has become the standard packaging substrate for cephalosporin and penicillin capsules in this enterprise.

HW-E. Conclusions and Outlook

With precise multi-dosage form adaptability (covering mainstream dosage forms such as solid and liquid preparations through thickness, state, and process adjustment to meet differentiated needs for formability, puncture resistance, and heat-sealing) and excellent full-dimensional barrier performance (effective protection against oxygen, water vapor, light, and microorganisms, meeting core requirements of pharmaceutical packaging), 8011 alloy aluminum foil has become a preferred solution for pharmaceutical packaging substrates. Its core technical advantages lie in: the solid solution strengthening effect of Al-Fe-Si alloy composition (balancing strength and ductility), the barrier mechanism of dense metal structure (near-zero permeability), and compliance with international pharmaceutical standards (meeting YBB, USP, ISO, etc.).
In the future, as pharmaceutical packaging moves toward “lightweight, environmental protection, and functionalization”, the technical optimization of 8011 alloy aluminum foil can focus on three directions:

1. Ultra-thin processing: Through multi-pass cold rolling (reduction rate ≥95%) and precision annealing control, reduce the thickness to 0.012-0.015mm, cutting material consumption by over 30% while maintaining elongation ≥20%, to adapt to the packaging of micro-dose preparations (e.g., sublingual tablets, implants).

2. Eco-friendly modification: Promote chromium-free passivation (zirconate, titanate) and degradable composite structures (Al-polylactic acid (PLA)) to meet global environmental regulations (e.g., EU ECODESIGN, China’s “dual carbon” goals).

3. Functional integration: Develop “barrier + intelligent monitoring” integrated aluminum foil, such as integrating pH-sensitive coatings (monitoring drug deterioration) and RFID tags (tracking drug flow) on the foil surface, to improve the intelligence level of pharmaceutical packaging and further consolidate its core position in high-end pharmaceutical packaging.