What are the key physical property differences between acrylic and polyurethane water-based inks?

Polyurethane water-based inks generally outperform acrylic inks in adhesion (4B vs. 2B on PET),Ethanol resistant wiping (200 rubs vs. 50 rubs), weather resistance (ΔE@500h of 1.8 vs. 5.2), and surface hardness (2H vs. HB). Acrylic inks excel in drying speed, achieving touch-dry in 18 seconds at 25℃ compared to polyurethane's 45 seconds for full cure, due to their physical drying mechanism versus chemical crosslinking.

In which specific food packaging applications are acrylic vs. polyurethane water-based inks recommended, and why?

Acrylic inks are suitable for ordinary food carton printing due to their cost-effectiveness and fast drying at room temperature. Polyurethane inks are preferred for retort pouches and frozen packaging because they can withstand high temperatures (up to 121℃ for Steaming and sterilization) and maintain chemical resistance, thanks to their chemical crosslinking structure that forms a durable, heat-stable film.

Acrylic vs. Polyurethane Water-Based Inks

Date: May 09 2025 From: Star Color Views:

With the vigorous development of green printing technology, acrylic and polyurethane water-based inks have become two mainstream systems, widely used in packaging, textiles, electronics, and other fields due to their low VOC emissions and safe, environmentally friendly properties. Although both belong to the category of water-based inks, their fundamental differences in chemical structure and curing mechanisms lead to significant disparities in physical properties, environmental performance, and application scenarios. Drawing on over a decade of experience in the printing industry, this article analyzes the differences between these two ink systems from the molecular level to practical applications, incorporating authoritative test data to provide a scientific reference for industry selection.

I. Differences in Chemical Structure and Reaction Mechanisms

Property	Acrylic Water-Based Ink	Polyurethane Water-Based Ink
Main Chain Structure	Linear polymer with C-C single bonds	Alternating copolymer with urethane bonds
Crosslinking Mechanism	Physical film formation (water evaporation)	Chemical crosslinking (isocyanate reaction)
Functional Groups	Carboxyl groups (-COOH)	Isocyanate groups (-NCO)
Curing Temperature	Ambient - 80℃	80-140℃ (triggers chemical crosslinking)
Molecular Weight Distribution	Broad (PDI=2.5-3.5)	Narrow (PDI=1.8-2.2)
Microscopic Characterization	FTIR Spectroscopy: Strong C=O peak at 1720cm⁻¹ TEM Imaging: Emulsion particle size 100-200nm	FTIR Spectroscopy: Characteristic NCO peak at 2270cm⁻¹ TEM Imaging: Uniform emulsion particle size 50-80nm

At the molecular level, acrylic inks rely on physical film formation of carboxyl groups, drying at room temperature; polyurethane inks form a crosslinked network through isocyanate groups, requiring high temperatures to trigger the reaction. These fundamental differences directly impact film-forming properties, weather resistance, and processing techniques.

II. Physical Property Testing Comparison

Test Item	Acrylic Water-Based Ink	Polyurethane Water-Based Ink	Test Standard
Adhesion (PET)	2B (Cross-Cut Test)	4B	ASTM D3359
Ethanol Resistance (Rubs)	50 rubs (failure)	200 rubs (no change)	GB/T 23989-2009
Weather Resistance (ΔE@500h)	5.2	1.8	ISO 11341
Surface Hardness	HB (Pencil Hardness)	2H	ISO 15184
Drying Speed (25℃)	18 seconds (touch-dry)	45 seconds (full cure)	ASTM D1640

Test data shows that polyurethane inks excel in adhesion, chemical resistance, weather resistance, and hardness, thanks to their dense crosslinked film structure. Acrylic inks, however, dominate in drying efficiency with a 18-second touch-dry time, ideal for scenarios sensitive to drying speed.

III. Environmental Performance and Compliance Standards

1. Hazardous Substances Comparison (ppm)

Substance	Acrylic System	Polyurethane System	Regulatory Limit
Glycol Ethers	1200	Not Detected	EPA ≤500 (TSCA)
APEO	Positive	Negative	REACH Annex XVII
Free Formaldehyde	8	<0.5	GB 38507-2020

2. Life Cycle Assessment (LCA)

Indicator	Acrylic (/kg Ink)	Polyurethane (/kg Ink)
Carbon Footprint	2.8kg CO₂eq	3.5kg CO₂eq
Non-Renewable Resource Consumption	4.3MJ	5.7MJ
Freshwater Ecotoxicity	0.45CTUe	0.62CTUe

In environmental performance, polyurethane systems meet strict international regulations (e.g., REACH, TSCA) due to their absence of glycol ethers and APEO. Acrylic systems have slightly better carbon footprint and freshwater ecotoxicity but require attention to excessive hazardous substances.

IV. Diverse Application Scenarios

Application Field	Acrylic Advantage Scenarios	Polyurethane Advantage Scenarios
Food Packaging	Ordinary carton printing	Retort pouches/frozen packaging
Electronics	Outer box labeling	Circuit board masking inks
Textiles	Low-cost textile printing	High-elasticity sportswear fabrics
Construction & Decoration	Indoor poster printing	Outdoor weather-resistant advertising films

The two systems complement each other: acrylic inks suit low-cost, room-temperature drying applications, while polyurethane inks are indispensable for high-temperature, high-wear, and high-weather resistance environments. For example, polyurethane inks can withstand 121℃ retort sterilization for food contact materials, whereas acrylic inks only meet basic carton printing needs.

V. Latest Technological Advancements

1. Acrylic System Upgrades

Nano-Modification: Adding SiO₂ aerogel (particle size <50nm) increases temperature resistance from 80℃ to 120℃, breaking through traditional heat resistance limitations.
Bio-Based Raw Materials: Replacing 30% of acrylic monomers with itaconic acid derivatives (derived from corn fermentation) boosts bio-based content to 45%, reducing reliance on petroleum-based materials.

2. Polyurethane System Innovations

Light-Triggered Curing: Introducing UV-responsive isocyanates reduces drying time from 45 seconds to 8 seconds, compatible with high-speed flexographic printing (speed >300m/min).
Self-Healing Coatings: Incorporating dynamic disulfide bonds enables 80%+ scratch repair at 50℃ within 2 hours, extending the service life of outdoor advertising films by 30%.

Recommendation: Zhongzhixing Water-Based Inks

Huizhou Zhongzhixing Color Technology Co., Ltd., a leading player in the water-based ink industry, offers differentiated solutions for both systems, balancing environmental protection and performance to adapt to various printing substrates and environments:

Food-Grade Safety Certification: Certified by ROHS, FDA, and SGS, with free formaldehyde <0.5ppm, compliant with GB 4806.14-2023 food safety standards, suitable for direct food contact applications like cake paper and aluminum foil packaging.
High Temperature Resistance & Adhesion: The SC9000 series withstands temperatures up to 220℃ and achieves 4B adhesion on PET, BOPP, and other substrates, meeting the demands of retort pouches and medical packaging.
High-Speed Printing Compatibility: Flexographic water-based inks support speeds up to 450m/min with VOC content <1%, far exceeding industry standards.

Committed to the core values of "environmental protection, efficiency, and safety," Zhongzhixing’s products are widely used in food packaging, hygiene materials (e.g., diapers, milk/beer cartons), and serve as an ideal alternative to traditional solvent-based inks. Choose Zhongzhixing for cutting-edge technology and sustainable development.