1. Introduction

DENSON SEP epoxy color paste is a pre-dispersed pigment concentrate designed for solvent-free and high-solids epoxy coating systems. This paper reviews its dispersion stability and compatibility with three major curing agent families—polyamide, alicyclic amine, and modified amine—based on colloid chemistry principles and engineering test data. For more technical literature, see DENSON technical articles.

2. Technical Features and Mechanism

Epoxy color paste is a pigment dispersion in epoxy resin carrier, where pigments are wetted by dispersants and mechanically dispersed to a target particle size. The SEP series uses nanoscale bead milling to achieve D50 ≤ 2.0 μm and fineness ≤ 15 μm, providing high color strength and low sedimentation. The dispersion mechanism follows DLVO theory: steric and electrostatic repulsion from adsorbed dispersant layers counteracts van der Waals attraction, preventing flocculation during storage and curing.

Figure 1: SEP epoxy color paste standard samples in glass beakers

3. Application Case 1: Polyamide Curing System for Industrial Flooring

In a 5,000 m2 epoxy flooring project, SEP-303 (gray) was dispersed into E-51 epoxy resin at 1.5 wt% using a high-speed disperser followed by bead milling. The cured film showed adhesion ≥ 4.0 MPa (GB/T 5210), wear resistance ≤ 0.02 g/1000r (GB/T 1768), and salt spray resistance ≥ 800 h (GB/T 1771). Color difference between batches ΔE ≤ 1.0 (GB/T 11186.3).

4. Application Case 2: Alicyclic Amine Curing System for Marine Anticorrosion

SEP-101 (red-brown) was formulated with IPDA-based curing agent for ballast tank coating. The system met IMO MSC.215(82) performance standards, with salt spray ≥ 1500 h, cathodic disbondment resistance −1.5 V/30 d (ISO 15711), and adhesion ≥ 4.5 MPa. The alicyclic amine showed good pigment wetting, with no visible flooding or floating after curing.

Figure 2: Laboratory nanobead mill used for SEP color paste dispersion

5. Application Case 3: Modified Amine Curing System for Electronic Potting

SEP-601 (black) was used in electronic potting compounds with modified amine curing. Volume resistivity ≥ 10¹³ Ω·cm (GB/T 1410), dielectric strength ≥ 20 kV/mm (GB/T 1408), and Tg ≥ 125°C. The color paste did not negatively impact curing shrinkage or electrical insulation properties.

6. Key Selection Parameters and Usage Recommendations

Usage recommendations: (1) Pre-mix color paste with epoxy resin for 10-15 min before adding curing agent; (2) recommended dosage 0.5-3.0 wt% depending on color; (3) store sealed at 5-35°C and use within 12 months.

Figure 3: Bench-top spectrophotometer for SEP color paste batch quality control

7. Conclusion

DENSON SEP epoxy color paste demonstrates excellent dispersion stability and broad compatibility with polyamide, alicyclic amine, and modified amine curing systems, making it suitable for industrial flooring, marine anticorrosion, and electronic potting applications.

8. FAQ

Q1: What is the typical dosage of SEP epoxy color paste?
A: The recommended dosage is 0.5-3.0 wt% based on total epoxy system weight, depending on pigment color and required film thickness.

Q2: Is SEP paste compatible with solvent-free epoxy systems?
A: Yes, SEP series is specifically designed for solvent-free and high-solids epoxy systems, with VOC < 50 g/L complying with GB 38508.

Q3: How to check batch color consistency?
A: Measure cured films with a bench-top spectrophotometer under D65 light source; batch-to-batch &Delta;E should be &le; 1.0 per GB/T 11186.3.

Q4: Does SEP color paste affect mechanical properties of cured epoxy?
A: At recommended dosage (&le; 3.0%), SEP paste does not significantly impact adhesion, impact resistance, or tensile strength of cured epoxy.

Q5: What is the shelf life of SEP epoxy color paste?
A: When stored sealed at 5-35&deg;C, the shelf life is 12 months. After opening, use promptly and reseal to avoid moisture uptake.