Why Masterbatch Is Preferred Over Pigment Powder in Plastic Coloring

Masterbatch is a concentrated mixture of pigments or dyes encapsulated into a carrier resin through a heat process. It offers a range of advantages over direct pigment powder coloring, especially in plastic extrusion, injection molding, and film blowing.

Advantages of Using Masterbatch

1. Improved Pigment Dispersion

During masterbatch production, pigments are finely processed to enhance dispersion and color strength. The carrier resin of the masterbatch matches the base plastic (e.g., PE, PP, ABS), ensuring excellent compatibility. Once melted, pigments distribute evenly within the polymer matrix.

2. Enhanced Pigment Stability

Direct pigments can absorb moisture and oxidize during storage, causing quality loss. Masterbatch encapsulates pigments in a resin carrier, protecting them from air and humidity, thus maintaining long-term stability.

3. Consistent Product Color

Masterbatch pellets are similar in size to polymer granules, making measurement and mixing more precise. This guarantees stable dosage and uniform color distribution in the final product.

4. Improved Operator Safety

Pigment powder can become airborne during handling, posing respiratory risks. Masterbatch eliminates this dust hazard, protecting worker health.

5. Cleaner Production Environment

No pigment dust means a cleaner, more efficient production floor.

6. Easy Handling

Masterbatch is easy to store, transport, and feed into processing machines.

Basic Components of Masterbatch

1.Pigments or Dyes

• Organic pigments: Phthalocyanine Blue, Phthalocyanine Green, Azo Red, Permanent Yellow, Permanent Violet, etc.

• Inorganic pigments: Titanium Dioxide, Carbon Black, Cadmium Red, Iron Oxide Red, etc.

2.Carrier Resin

The polymer base of the masterbatch, ideally matching the processing resin for best compatibility and flowability.

3.Dispersing Agents

Promote uniform pigment distribution and prevent clumping. Common agents include low molecular weight polyethylene wax and stearates.

4.Additives (optional)

Such as flame retardants, brighteners, anti-static agents, UV stabilizers, antioxidants, and antimicrobial agents.

Types & Grades of Masterbatch

By Carrier Resin:

• PE Masterbatch

• PP Masterbatch

• ABS Masterbatch

• PVC Masterbatch

• EVA Masterbatch

By Application:

• Injection Molding Masterbatch (high-grade & general-purpose)

• Blow Molding Masterbatch (high-grade & general-purpose)

• Fiber Spinning Masterbatch

• Film Blowing Masterbatch

By Product Grade:

• High-grade: For cosmetics packaging, toys, and appliance housings.

• General-purpose: For daily-use items and containers.

• Low-grade: For non-critical products like trash bins.

Specialized vs. Universal Masterbatch

• Specialized Masterbatch: Uses the same resin as the target product (e.g., PP masterbatch for PP products). Offers best color predictability and physical properties.

• Universal Masterbatch: Uses a low-melting resin (often PE) as the carrier, suitable for multiple resins. While convenient, it has limited compatibility, lower color accuracy, and can weaken product strength.

Note: Most professional masterbatch manufacturers avoid universal types due to their performance drawbacks.

Functional Masterbatch

Masterbatch can be customized to combine color with functional properties such as:

• Flame retardancy

• UV resistance

• Anti-static performance

• Antioxidation

• Antimicrobial properties

Heat Resistance of Masterbatch

The heat stability of masterbatch is aligned with the processing resin’s requirements. Under normal processing temperatures, it maintains color integrity. Excessive heat or prolonged machine stoppage may cause discoloration.

Masterbatch vs. Pre-colored Pellets

Advantages of Masterbatch Coloring:

1.One-step coloring during product processing.

2.Reduced polymer degradation from extra heating cycles.

3.Lower energy consumption.

Masterbatch Production Processes

1.Ink Method: Pigment is pre-dispersed in resin using a three-roll mill, then compounded and pelletized via single-screw or twin-screw extruders.

2.Flushing Method: Pigments are ground in water with dispersants, transferred into an oil phase, dried, and pelletized.

3.Kneading Method: Pigment and oily carriers are kneaded to form stable dispersion.

4.Metal Soap Method: Pigments are coated with metallic stearates to prevent flocculation.

Processing equipment: Single-screw extruders, twin-screw extruders, high-torque compounding lines.

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