What is the selection and combination of food flexible packaging materials?

Constructing the "Intelligent Garment" for Food: An Analysis of Selection and Combination Strategies for Food Flexible Packaging Materials

Abstract: In the modern food industry system, packaging is far more than a simple container; it is a critical link in ensuring food safety, extending shelf life, conveying brand value, and meeting convenient consumption needs. Among these, flexible packaging,lightweight, flexible, cost-effective, and high design freedom advantages, holds a significant position. However, faced with a wide array of substrates, functional layers, and composite technologies, how to scientifically and precisely select and combine materials has become a core issue that food production enterprises, packaging engineers, and R&D personnel must deeply study. This article will systematically analyze the internal logic and combination strategies for selecting food flexible packaging materials, aiming to provide a professional and rigorous decision-making framework for industry practice.

I. Core Functions and Performance Requirements of Food Flexible Packaging

Before selecting materials, it is essential to clarify the core mission the packaging must achieve. This forms the fundamental starting point for material selection.

Protection and Barrier Properties: This is the primary function of packaging.

Oxygen Barrier: Prevents oxygen ingress leading to food oxidation, rancidity, discoloration, and microbial growth.

Moisture Barrier: Prevents water vapor intrusion (causing dry goods to become damp) or escape (causing fruits, vegetables, and meats to lose water and weight).

Light Barrier: Especially blocking ultraviolet light to prevent fat photo-oxidation, vitamin decomposition, and food fading.

Aroma Retention: Prevents the loss of inherent food aromas and blocks the intrusion of external odors.

Mechanical Strength: Possesses sufficient tensile strength, tear resistance, and puncture resistance (for bones, nuts, etc.) to ensure integrity during transportation and stacking.

Safety and Hygiene:

Material Compliance: All materials must comply with national and target market regulations for food contact materials (such as China's GB 4806 series standards, EU's (EU) No 10/2011, etc.), ensuring no migration of toxic or harmful substances.

Chemical Inertness: Materials should not undergo chemical reactions with food components, affecting food flavor and safety.

Processability and Suitability:

Heat Sealability: Suitable for high-speed automatic filling and sealing equipment, forming strong, well-sealed closures.

Temperature Resistance: Able to withstand subsequent processing or usage conditions such as sterilization (e.g., pasteurization, high-temperature retorting), freezing, or microwave heating.

Commercial and User Experience:

Printability: Surface energy supports high-quality printing to display brand image and product information.

Convenience: Easy to open, reclose, carry, and use (e.g., stand-up pouches, spouted packaging).

Sustainability: While meeting functional requirements, consider the material's recyclability, biodegradability, or use of recycled materials, responding to environmental trends.

II. Performance Analysis of Common Flexible Packaging Materials

No single material can perfectly meet all needs. Therefore, understanding the characteristics of various base materials is a prerequisite for combination design.

III. Material Combination Strategies: A Systems Engineering Approach from Single Layer to Composite Structures

The limitations of single materials have given rise to composite packaging technology. By combining two or more materials with different properties, a "functional synergy" is formed, achieving a "1+1 > 2" effect.

Design Logic of Composite Structures

A typical composite structure usually consists of an outer layer, middle layer, and inner layer, each with its own role:

Outer Layer: Undertakes the roles of mechanical strength, printing display, and wear resistance. Often uses materials with high strength and good printability like BOPP, BOPET, PA.

Middle Layer: Undertakes the core barrier function. Often uses high-barrier materials like aluminum foil, metallized film, EVOH, PVDC. For EVOH, it must be sandwiched between moisture-proof layers (like PE, PP) to protect it from humidity.

Inner Layer: Directly contacts the food, undertaking heat sealing, hygiene, safety, and resistance to content corrosion. Often uses materials with excellent heat sealability and chemical stability like CPP, PE.

Examples of Typical Composite Structures

Medium Barrier Structure: BOPP / VMPET / PE

Interpretation: BOPP provides aesthetic printing and stiffness, VMPET provides good oxygen/moisture barrier and gloss, PE provides reliable heat sealing. Suitable for potato chips, puffed snacks.

High Barrier Retort Structure: PET / AL / CPP

Interpretation: PET provides strength and print surface, aluminum foil (AL) provides comprehensive ultimate barrier and light blocking, CPP provides the heat seal layer resistant to high-temperature retorting. Used for meat sauces, dishes, and other ambient temperature distribution products.

High Barrier Non-Aluminum Foil Structure: PET / EVOH / PE

Interpretation: PET as the outer layer, EVOH provides top-tier oxygen barrier, PE acts as the inner layer to protect EVOH and provide heat sealing. This structure is transparent, suitable for sauces, hams, etc., where content display is needed, and is microwaveable.

Liquid Packaging Structure: PE / Paper / AL / PE

Interpretation: This is a simplified structure of aseptic bricks like Tetra Pak. Paperboard provides rigidity, aluminum foil provides absolute barrier, inner and outer PE layers provide lamination with the paperboard and the food-contact heat seal layer, respectively.

Selection of Combination Processes

Dry Lamination: Most widely used, suitable for a wide range of materials, high strength, but may involve solvent residue issues.

Solventless Lamination: Environmentally friendly, no solvent residue, low cost, currently the mainstream development trend.

Co-extrusion: Multiple layers of material are extruded at once in a molten state, resulting in highly integrated structure and low cost, but material combinations are limited by similar processing temperatures.

Conclusion

The selection and combination of food flexible packaging materials is an interdisciplinary field integrating materials science, food chemistry, mechanical engineering, and marketing. It is by no means a simple piling up of materials, but rather a systems engineering project based on a deep understanding of product requirements, material characteristics, and processing technologies. In today's context of increasingly stringent environmental regulations and diversifying consumer demands, the future development of flexible packaging will place greater emphasis on high functionality, lightweighting, intelligence, and sustainability. Only by adhering to a professional and rigorous attitude and dynamically tracking the latest advancements in materials and technology can we design "intelligent garments" that perfectly protect food quality and safety while aligning with contemporary trends and business goals, thereby remaining invincible in the fierce market competition.