Plastic Colorants: Types and Performance Guide

time：2025-05-13 click：

Plastics are rarely boring—thanks to colorants, they come in every shade imaginable. But not all colorants are the same. Some fade in sunlight, others bleed during molding, and a few might even be toxic. This guide breaks down the most common plastic colorants, their pros and cons, and how to choose the right one for your project.

Why Plastic Color Selection Matters

Picking the wrong colorant can lead to:

✔ Fading (poor UV resistance)
✔ Brittleness (some pigments weaken plastic)
✔ Regulatory issues (e.g., banned cadmium pigments)
✔ Recycling problems (black plastics often get trashed)

Fun Fact: The iconic "Barbie Pink" requires a special, ultra-stable pigment to stay vibrant for decades.

Types of Plastic Colorants

1. Dyes vs. Pigments – The Key Differences

Property	Dyes	Pigments
Solubility	Dissolve into plastic	Disperse as solid particles
Transparency	Transparent	Opaque or semi-opaque
Heat Stability	Lower (can degrade)	Higher (more resistant)
Cost	Generally cheaper	More expensive

Best For:

Dyes → Clear plastics (water bottles, lenses)

Pigments → Opaque products (toys, automotive parts)

2. Most Common Pigment Types

Pigment	Color Range	Performance	Common Uses
Titanium Dioxide	White	High opacity, UV-resistant	Food packaging, PVC pipes
Carbon Black	Black	Excellent durability, conductive	Tires, electronics
Phthalocyanine	Blue/Green	Bright, heat-stable, cost-effective	Toys, household items
Iron Oxide	Red/Yellow	Non-toxic, weather-resistant	Outdoor furniture
Cadmium*	Bright Reds/Yellows	Toxic (banned in many regions)	Legacy industrial uses

*Warning: Cadmium pigments are restricted under REACH & RoHS due to toxicity.

Performance Factors to Consider

Not all colorants behave the same way. Key factors include:

1. Heat Resistance

Low-stability dyes burn during injection molding (200°C+).

High-performance pigments survive extrusion (300°C+).

2. Lightfastness (UV Resistance)

Poor: Basic organic dyes fade quickly outdoors.

Excellent: Inorganic pigments (e.g., titanium dioxide) last years.

3. Chemical Resistance

Automotive plastics must resist oil, fuel, and cleaners.

Medical plastics need FDA-approved, non-leaching dyes.

4. Environmental Impact

Eco-friendly options: Bio-based pigments, non-toxic alternatives.

Recycling issues: Black plastics are hard to sort in recycling plants.

How to Choose the Right Colorant ？

Check regulatory compliance (FDA, REACH, RoHS).

Test for heat/light stability before mass production.

Consider end-of-life – Will it be recycled or landfilled?

Balance cost vs. performance – Cheap dyes may fail faster.