What are the key differences in formulation between water-based inks and solvent-based inks?

Water-based inks use water and co-solvents like propylene glycol methyl ether (60-80% water content) as carriers, with acrylic or polyurethane resins forming the film. They contain ≤50g/L VOCs. Solvent-based inks rely on volatile organic compounds like ethyl acetate/toluene (50-70% content) with chlorinated rubber/polyurethane resins, typically containing 300-500g/L VOCs. The resin systems differ fundamentally - water-based versions require self-emulsifying modifications while solvent-based resins dissolve directly in organic solvents.

Why do solvent-based inks still dominate certain applications despite environmental concerns?

Solvent-based inks maintain advantages in: 1) Drying speed (0.5-2 mins vs 2-5 mins for water-based), 2) Adhesion on non-polar substrates like metals (5B vs 4B on PET via ASTM D3359), 3) High-precision printing (200-300LPI vs 150-200LPI). Their resin systems create denser films through oxidative curing, essential for extreme conditions like metal can printing (600+ cans/min) and automotive coatings requiring 10-year weatherability (ΔE<2).

Comparison of Water-based and Solvent-based Ink Formulations

Date: May 26 2025 From: Star Color Views:

The formulation designs of water-based inks and solvent-based inks form completely different component architectures due to their core solvents. This difference directly determines the physical and chemical properties, printing adaptability, and environmental attributes of the inks.

I. Comparison of Core Formulation Components

1. Solvent Systems: The Game Between Environmental Protection and Efficiency

Component	Water-based Ink	Solvent-based Ink	Technical Differences
Main Solvent	Deionized water (60-80%)	Ethyl acetate/toluene (50-70%)	High polarity of water → poor wettability but near-zero VOCs
Co-solvent	Propylene glycol methyl ether (5-15%)	Isopropyl alcohol/butanone (10-20%)	Adjust volatility rate and dissolving power
VOC Content	≤50g/L	300-500g/L	Environmental regulations drive the substitution of water-based inks

2. Comparison of Resin Systems

Type	Water-based Ink	Solvent-based Ink	Performance
Main Resin	Water-based polyurethane dispersion (PUD, Tg -20~60℃)	Chlorinated vinyl acetate resin/polyurethane (soluble in esters)	Water-based resins require self-emulsifying modification
Curing Mechanism	Water evaporation + self-crosslinking	Solvent evaporation + oxidation polymerization	Higher film density in solvent-based inks
Adhesion (PET)	4B-5B (ASTM D3359)	5B	Water-based polyurethane approaches solvent-based performance on non-polar substrates

Experimental Data:

Water-based Polyurethane:
- Solid content: 30-40% (requires low-temperature drying)
- Peel strength: 5.2N/15mm (BOPP/CPP composite structure)
- Abrasion resistance: Weight loss ≤15mg/1000 cycles (Taber test, CS-10 wheel, 1kg load)
Solvent-based Polyurethane:
- Solid content: 20-25% (high solvent proportion)
- Peel strength: 6.8N/15mm
- Abrasion resistance: Weight loss ≤10mg/1000 cycles

3. Comparison of Pigments and Dispersion Systems

Component	Water-based Ink	Solvent-based Ink	Technical Challenges
Pigment Type	Alkali-resistant (stable at pH 8-9)	Conventional organic/inorganic pigments	Water-based systems require anti-flocculation treatment
Dispersant	Polyacrylate (HLB 12-14)	Phosphate esters (polar matching)	Higher dosage of water-based dispersants (1-3%)
Grinding Process	Nano sand grinding (zirconia beads 0.3mm)	Three-roll grinding (particle size D50 1-5μm)	Higher shear force required for water-based inks

Actual Measurement Comparison: Carbon black water-based ink has D50=0.2μm (solvent-based: 0.5μm), but storage stability is 30% worse.

4. Comparison of Functional Additives

Additive Type	Water-based Ink	Solvent-based Ink	Mechanism of Action
Defoamer	Polyether-modified siloxane (0.1-0.5%)	Mineral oil-based (0.05-0.2%)	Stronger defoaming needed due to high foam stability in water-based systems
Leveling Agent	Fluorocarbon compounds (0.05-0.1%)	Silicone-based (0.02-0.08%)	Reduces surface tension differences
Preservative	Isothiazolinone (0.1-0.3%)	Not required	Microbial growth prevention in water-based systems

II. Performance Comparison Matrix of Formulations

Index	Water-based Ink	Solvent-based Ink	Root Cause of Gap
Drying Speed (25℃)	2-5 minutes (requires hot air)	0.5-2 minutes (natural evaporation)	High latent heat of water evaporation (2257kJ/kg)
Water Resistance (24h immersion)	3-4 grades (prone to blistering)	Grade 5 (no change)	Residual hydrophilic groups in resins
Printing Precision	180-250LPI	200-300LPI	Slightly lower fluidity in water-based inks
Storage Stability	6-12 months (anti-freezing required)	18-24 months	Tendency to phase separate/mildew in water-based systems

III. Analysis of Typical Formulation Cases

1. Water-based Plastic Ink Formulation

Component	Proportion	Function
Water-based acrylic resin	35%	Film formation/adhesion
Phthalocyanine blue pigment	12%	Color development
Propylene glycol methyl ether	8%	Reduces surface tension
Polyurethane thickener	0.8%	Thixotropy control
Bactericide	0.2%	Anticorrosion

Performance Parameters: Viscosity 35s (coating cup #4), adhesion 4B, VOC 42g/L

2. Solvent-based Composite Ink Formulation

Component	Proportion	Function
Chlorinated vinyl acetate resin	25%	Heat-resistant/high adhesion
Benzidine yellow pigment	15%	High covering power
Ethyl acetate	45%	Fast-drying solvent
Polyethylene wax	1.5%	Anti-scratch
Dispersant	2%	Pigment stabilization

Performance Parameters: Viscosity 22s (coating cup #4), adhesion 5B, VOC 380g/L

The formulation differences between water-based inks and solvent-based inks essentially represent a trade-off between environmental protection and performance. Water-based systems are gradually breaking through bottlenecks through resin modification and nanotechnology, while solvent-based inks remain irreplaceable in special fields due to their mature processes. Over the next decade, the two will coexist long-term, evolving dynamically in the game between "low-carbon regulations" and "performance needs."