How to Choose Food Flexible Packaging Ink Brands and Solvent Combinations

A Professional Choice, A Foundation of Safety: The Scientific Decision-Making Path for Food Flexible Packaging Ink Brands and Solvent Combinations

In today's highly developed food industry, flexible packaging has become a core carrier for food protection and brand display due to its lightweight, durability, high barrier properties, and rich printing effects. However, behind these glossy and attractive packages, the importance of selecting inks and solvents—key materials that directly or indirectly contact food—cannot be overstated. A poor decision can, at best, affect printing quality and production efficiency, and at worst, trigger food safety risks, legal disputes, and devastating blows to brand reputation. Therefore, establishing a scientific, systematic, and forward-looking system for selecting ink brands and solvent combinations is an essential task for every responsible flexible packaging manufacturer.

This article will follow the core principle of "safety and compliance as the premise, performance matching as the core, production adaptability as the key, and cost-effectiveness as the guarantee" to dissect the entire process of this professional decision-making step by step.

Part 1: The Foundation and Red Line—Safety and Compliance Assessment

Before any technical or economic considerations, safety and compliance are non-negotiable bottom lines.

Regulatory Compliance: The Passport to Global Markets

Food packaging inks must adhere to strict regulations in global and target markets.

Chinese Standards: Focus on the general requirements for food contact materials and inks under the GB 4806 series, as well as testing methods for migrants like GB 31604.1-2015. Compliance with the Food Safety Law and related announcements is also required.

International Standards:

European Union: Follow EU No. 10/2011 (Regulation on plastic food contact materials) and its subsequent amendments, while paying attention to specific requirements of member states. Switzerland's Ordinance (SR 817.023.21) imposes particularly strict requirements on harmful substances in inks and is often regarded as a de facto industry benchmark.

United States: Adhere to the relevant provisions of the FDA's Chapter 21 CFR to ensure ink components are safe under intended use conditions.

Brand Owner Standards: Many large food companies (e.g., Nestlé, Mars, Coca-Cola) have more stringent "negative substance lists" and compliance requirements than regulations. When selecting an ink brand, confirm it meets these customer standards.

Low Migration and Non-Benzene/Non-Ketone Trends

Low Migration Inks: This is the current mainstream and future direction. Their design ensures that ink components, especially photoinitiators, monomers, and solvent residues, do not migrate significantly into food during packaging, storage, or transportation. When selecting a brand, request comprehensive migration and specific migration test reports from suppliers for specific food simulants.

Non-Benzene/Non-Ketone: Due to the potential toxicity and residue risks of benzene and ketone solvents, non-benzene/non-ketone inks have become the industry standard. Leading ink brands have completed their technological transition, offering ink products based on safer solvent systems like esters and alcohols.

Brand Selection Insight: At this stage, prioritize well-known brands with a long history, strong R&D capabilities, and global compliance experience and support. Examples include Siegwerk, Hanghua Co., Ltd., DIC, and PPG. These companies typically excel in regulatory tracking, product certification, and providing test data, helping you avoid significant compliance risks.

Part 2: Performance and Compatibility—Systematic Matching of Technical Parameters

After ensuring safety and compliance, technically achieve precise matching of inks with substrates, processes, and end requirements.

Ink System Selection: Solvent-Based, Water-Based, or UV?

Solvent-Based Inks: Still dominant in medium to high-speed printing, especially excellent on films like PET, BOPP, and NY. They offer fast drying speed, strong adhesion, and good printability. Solvent combination selection is core, detailed later.

Water-Based Inks: Environmentally friendly, very low VOCs emissions, high safety, often used for paper and paper-plastic composite packaging. However, drying speed, adhesion, and print vibrancy on non-absorbent films remain technical challenges.

UV-LED Inks: Instant curing, no solvent emissions, high print quality. Particularly suitable for labels, caps, and effects requiring local glazing. Pay attention to low migration formulations and thorough curing.

Substrate Compatibility Testing

Different substrate films (e.g., BOPP, PET, NY, PE, AL) have varying surface energy and polarity. Strict adhesion tests (cross-cut test), rub resistance, retort resistance, and content resistance (acid, alkali, oil) tests are essential. Brands should provide specialized ink series for different substrates.

Print Effect and Post-Processing Adaptability

Color Performance: Includes color strength, transparency, and vibrancy. High-end brand inks typically have stable hues and minimal batch variation, aiding color management.

Resistance: Such as lightfastness (to prevent shelf-life fading) and water/retort resistance (for high-temperature sterilization packaging).

Compatibility with Downstream Processes: The ink layer must be compatible with lamination adhesives (dry lamination, solvent-free lamination), metallization processes, and bag-making heat sealing, without issues like "color bleeding" or "delamination."

Brand Selection Insight: At this stage, choose brands with comprehensive product lines and strong technical support. They can provide full solutions from surface printing to reverse printing, from ordinary packaging to water/retort packaging, and send technical personnel to assist with proofing and troubleshooting.

Part 3: The Core Engine—Scientific Formulation and Optimization of Solvent Combinations

For mainstream solvent-based inks, solvents are the "lifeblood" of the ink, and their combination directly determines the success of the printing process.

Core Functions of Solvents

Dissolving Resins: Form the vehicle, the foundation of ink film formation.

Adjusting Viscosity: Adapt to different printing speeds and requirements.

Controlling Drying Speed: Match the printing press oven temperature and air speed for perfect drying.

The "Golden Triangle" Balance of Solvent Combinations

An ideal solvent formulation requires the best balance between dissolving power, drying speed, and cost.

Dissolving Power: Ensures complete resin dissolution, ink stability, and prevents "pigment reagglomeration" or "gelling." True solvents (e.g., esters, ketones) and diluents (e.g., alcohols) are often used together.

Drying Speed: Requires gradient volatility design. Too fast can cause plate scumming or drying on the plate; too slow can lead to high residue and blocking. A typical combination blends fast-drying solvents (e.g., ethyl acetate), medium-drying solvents (e.g., ethanol), and slow-drying solvents (e.g., n-propanol, isopropanol) in specific ratios.

Cost and Safety: Optimize the formulation to control costs while meeting performance requirements, ensuring all solvents' flash points comply with safety production regulations.

Dynamic Adjustment in Practice

Standard Formulations: Ink brands provide "standard diluent formulations" for different ink types and printing speeds.

Environmental Adaptability Adjustments: Fine-tune based on workshop temperature and humidity. In high temperature and humidity, increase the proportion of fast-drying solvents to prevent moisture absorption reducing dissolving power; in low temperature and humidity, reduce fast-drying solvents to prevent plate drying.

Printing Speed Adaptation: Higher speeds require faster drying, necessitating an increased proportion of fast-drying solvents.

Synergy Between Brand and Solvent Combination: Excellent ink brands not only provide high-quality inks but also a scientific, transparent, production-guiding solvent system. They clearly explain each solvent's purpose, formulation principles, and adjustment methods, and strictly control solvent purity to minimize the impact of impurities on print quality and safety.

Conclusion

Selecting food flexible packaging ink brands and solvent combinations is a complex systematic project integrating materials science, chemical engineering, regulatory knowledge, and production practice. It requires decision-makers to have a forward-looking vision and a rigorous attitude. Abandon short-sighted "price-only" approaches and instead ally with excellent brands that treat safety as paramount, are driven by technology, and create value through service. Only then can you strengthen the line of defense for food safety, showcase the brilliance of your brand image, and achieve sustainable enterprise development in the fierce market competition.