Plastic Pigments - The complete guide on How Colorants Work | 3devo

In the field of Fused Deposition Modeling (FDM) 3D printing, the scope for innovation is virtually limitless. The array of available thermoplastics is large, encompassing materials such as PLA, ABS, TPU, PA6, and PEEK, among others. Each of these materials exists in many forms, specifications, and grades, offering multiple options for various applications.

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While 3D-printed objects often fulfill roles in rapid prototyping and functional applications, the potential for customization extends beyond mere form and function. Indeed, the aesthetic aspect—particularly color—plays a critical role in differentiating products. This article explores the nuanced subject of filament customization, with a particular emphasis on the employment of masterbatches to imbue 3D-printing filaments with vibrant and enduring colors.

What Are Pigment Colorants Anyway?

Pigment colorants play a crucial role in determining the appearance and quality of 3D-printed objects. These colorants are added to the base polymer material to give it a specific hue. Unlike dyes, which dissolve into the material, pigments are insoluble particles that are mixed into the polymer matrix.

The addition of pigments occurs in minimal proportions, yet the impact on the filament's color is significant. One key advantage of pigments is their resistance to various environmental factors, such as light and heat, which contribute to the long-term stability of the product's color. The inert nature of pigments also ensures that they do not interfere with the chemical structure of the polymer, thus maintaining the material's inherent properties. This makes pigments a preferred choice for applications that require both aesthetic appeal and functional integrity.

In summary, pigment colorants are essential in 3D printing, offering both vibrant colors and durability without compromising the material's structural integrity.

Curious about experimenting with pigment colorants? Our Filament Maker can help! Learn more!

Understanding Masterbatches

What Are Masterbatches?

A polymer masterbatch is a concentrated mixture composed of a base polymer and various additives or agents, such as pigments, fillers, stabilizers, and other processing aids that you want to infuse into your base polymer.

Let’s assume your base polymer is ABS. However, the masterbatch would also be made of ABS, containing a certain concentration of additives. Typically, 2% of the masterbatch is enough to modify the properties of the full batch. We can see it like this: 98% of virgin ABS + 2% of ABS masterbatch = 100% of enhanced ABS. Masterbatches are polymer-specific – an ABS masterbatch cannot be blended into PLA filament.

How Do Masterbatches Work?

These masterbatches serve as convenient and efficient methods for incorporating specific properties, colors, or functionalities into polymers during manufacturing. Masterbatches are typically produced via a compounding process, during which the additives are thoroughly mixed and dispersed within the polymer matrix, resulting in a homogenous blend that can be easily incorporated into end products. A small pouch of masterbatch pellets at a lab scale will help you enhance several kilograms of polymer. Masterbatches come with speed and freedom of experimentation.

The Focus on Pigment Masterbatches

Characteristics

In the case of pigment masterbatch, the additive in focus is pigment. Pigments are finely ground, colored particles that are inert in the polymer matrix, meaning that the pigment is to be dispersed into the base polymer without reacting chemically. This characteristic is pivotal, as it enables the pigments to maintain their color integrity while weaving seamlessly into the filament's structure.

The Role of the Carrier

Pigment masterbatches are precisely formulated mixtures containing a high concentration of pigment dispersed within a compatible polymer carrier. Said carrier acts as a medium for the pigments and facilitates their uniform dispersion within the polymer melt, ensuring consistent and even coloration throughout the final product. By melting inside the extruder, the carrier will release the pigment into the whole matrix, resulting in colored filament.

Why not use pure pigment?

Pigments are colorful substances ground into very fine powder. Adding pure pigment powder to virgin polymer is possible but challenging. The challenges are:

• Dosing the right proportion of polymer vs pigment
• Feeding particles of different shapes into one system homogeneously. Including fine powder, which is also difficult to handle
• Mixing homogeneously once the plastic melts

Certain twin-screw extruders are specialized in such mixing but are not suited for filament making. Sequencing the process into 2 steps is the easiest strategy:

• Pre-compounding the plastic and pigment into masterbatch pellets. Or buying the masterbatch pre-made