What is the migration phenomenon in packaging inks?

Migration refers to the transfer of ink chemicals (monomers, photoinitiators) to products via direct contact (Fick's law), vapor (VOCs), or heat (e.g., microwaved food). 2022 EU data linked 34% of food contamination to ink migration, involving harmful substances like aniline.

What defines low-migration inks, and why are they safer?

They meet strict limits: EU/US/China set total migration, benzene, and lead caps. Using high-molecular prepolymers (>1000Da), they reduce migration risk to 1/50 of traditional inks. Key technologies include safe raw materials, optimized curing, molecular barriers, and smart monitoring.

What are low migration inks?

Date: Apr 21 2025 From: Star Color Views:

The migration of inks used in packaging and printing is a significant concern. Data from the EU's RASFF notification system in 2022 revealed that 34% of food contamination incidents were related to the migration of packaging inks. Chemical components in inks, such as monomers, photoinitiators, and plasticizers, can transfer through various pathways, posing threats to the safety of food, pharmaceuticals, and other products.

I. Definition of Low-Migration Inks

1.1 What is the Migration Phenomenon?

The migration phenomenon refers to the transfer of chemical components in inks when they come into contact with products. It mainly occurs through the following three pathways:

Direct Migration: Substances penetrate through the contact surface, following Fick's laws of diffusion.
Indirect Migration: Volatile organic compounds (VOCs) spread through the gas phase.
Temperature-Driven Migration: High-temperature environments accelerate molecular movement, commonly seen in the packaging of microwaveable foods.

The hazards of the migration phenomenon cannot be underestimated. According to the EU's RASFF notification system data in 2022, 34% of food contamination incidents were associated with the migration of packaging inks, involving harmful substances such as aniline and phthalates.

1.2 Criteria for Defining Low-Migration Inks

Testing standards for low-migration inks vary across regions, as shown in the following table:

Testing Items	EU Standard (EU 10/2011)	US FDA 21 CFR	China GB 9685
Total Migration	≤10mg/dm²	≤0.1mg/in²	≤5mg/dm²
Benzene Series	≤0.01ppm	Not Detected	≤0.02ppm
Heavy Metals (Pb)	≤0.5mg/kg	≤1ppm	≤0.3mg/kg

Modern low-migration inks use high-molecular-weight prepolymers (molecular weight > 1000Da), reducing the migration risk to 1/50 of that of traditional inks, achieving a significant technological breakthrough.

What are low migration inks?

II. Four Core Technologies for Achieving Low Migration

2.1 Stringent Raw Material Screening

Safe Monomer Library: Only substances listed in the EFSA positive list are selected, such as isobornyl acrylate.
Photoinitiator Substitution Solutions:
- Traditional Type: Benzophenone (high migration risk).
- Low-Migration Type: Ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate (TPO-L).

2.2 Curing Process Optimization

Parameters	Conventional UV Curing	Low-Migration Optimization Scheme
Energy Density	80 - 120mJ/cm²	150 - 200mJ/cm²
Inert Gas Environment	None	Nitrogen purity ≥ 99.999%
Post-Curing Treatment	None	60℃ hot air assistance for 2 minutes

2.3 Molecular Structure Design

Increased Crosslink Density: The proportion of difunctional monomers is ≥ 35%.
Molecular Barrier Technology: Nano-scale zeolites (pore size ≤ 3Å) are added to adsorb free small molecules.

2.4 Intelligent Monitoring System

Embedded Sensors: Real-time monitoring of the concentration of migrating substances with an accuracy of 0.1ppb.
Blockchain Traceability: Recording the entire process data from ink production to printing, in compliance with FDA CFR Part 11.

III. Key Application Scenarios and Test Data

3.1 Food Packaging

Take the printing of baby milk powder cans as an example. Under the test conditions of 40℃ for 10 days (simulating an 18-month shelf life), the nonylphenol migration was ≤ 0.003ppm, lower than the EU limit of 0.01ppm.

3.2 Pharmaceutical Packaging

Blister aluminum foil printing has the following characteristics:

Gamma Ray Sterilization Resistance: After 50kGy irradiation, the adhesion remains at level 4B (ASTM D3359).
Chemical Stability: No substance release in pH 1.2 - 8.0 simulated solutions.

3.3 Electronics

Printing on wearable devices has passed the following tests:

Artificial Sweat Immersion Test: 48 hours (ISO 3160-2).
Abrasion Resistance: Withstood > 500 cycles of steel wool rubbing (ASTM D5264).

Zhongzhixing Low-Migration Water-Based Inks

Among low-migration ink products, Zhongzhixing low-migration water-based inks stand out. Using water as the solvent, these inks significantly reduce the migration risks associated with organic solvents. They strictly adhere to international safety standards, integrate the four core technologies, and offer excellent printing adaptability and color expressive. Whether for food, pharmaceutical packaging, or electronics printing, Zhongzhixing low-migration water-based inks provide reliable safety guarantees, making them an ideal choice for enterprises aiming for safe and high-quality printing.