Masterbatch and colour concentrates — additive granulate in transport and transloading

Definition

Masterbatch is a concentrated dye or functional additive embedded in a polymer carrier, supplied as granulate with a grain size close to the base plastics and dosed into them at a small share — most often a few percent — during processing. Instead of working with a pure, dusting pigment or powder additive, the processor adds ready granulate that disperses evenly in the plastic melt.

From the terminal’s perspective, masterbatch is a material with an important logistical feature: it flows through the same stream as the base granulate, often together with it, and is handled almost identically. The difference lies not in the physics of the transfer but in the weight of the individual batch and in the absolute requirement of cleanliness — because a few percent of concentrate decides the quality of the whole product.

What a masterbatch is

Masterbatch (in Polish most often “colour concentrate” or “additive concentrate”) is a semi-finished product of the plastics industry. Its essence is enclosing an active ingredient — a pigment or functional additive — in a polymer carrier at a high concentration, much higher than the target in the finished product. The carrier is usually the same or a compatible plastic to which the concentrate will go: for polyethylene products PE carriers are used, for polypropylene — PP carriers, and there are also concentrates on universal carriers.

The mechanism of use is simple: the processor mixes base granulate with masterbatch in a set proportion (e.g. 2-4%), and during plasticisation in the extruder or injection-moulding machine the concentrate “releases” the pigment or additive into the whole mass of plastic. The result is uniform colouring or the imparting of a desired property — UV resistance, antistatic behaviour, slip, flame retardancy — without the need to store and dose inconvenient powders.

The granulate form is key here. A pigment in pure powder form, such as carbon black or titanium dioxide, dusts strongly, is hard to distribute evenly and soils the surroundings. Masterbatch solves this problem at the level of logistics and processing at once: it delivers the same pigment, but in a clean, free-flowing, easily dosed granulate.

Types of masterbatch

The market divides masterbatches by the function of the active ingredient. In terminal practice we encounter all the types below — they differ in composition but behave similarly in transloading.

Colour masterbatch is the colour concentrates — the most numerous and most varied group, covering the full palette of colours selected for a specific product. From the transloading cleanliness point of view it is the most sensitive group, because every intense dye easily contaminates an adjacent batch and is visible in the finished product.

White masterbatch is based on titanium dioxide — the strongest white pigment. It is highly opaque and very “soiling” with light dust when used as a loose pigment, which is why the granulate form is especially desirable here. Black masterbatch is based on carbon black; it imparts blackness and at the same time protects the plastic against UV radiation, which makes it the standard in products used outdoors, such as pipes, agricultural films or technical elements.

Additive masterbatch is concentrates of functional additives — without colouring. It includes UV and thermal stabilisers, antistatics, slip agents, anti-blocking agents and flame retardants. This group is most closely linked with the topic of plastic additives, because masterbatch is simply the form in which these additives most conveniently reach processing.

Filler masterbatch is concentrates of mineral fillers, most often calcium carbonate. They are used to modify properties and reduce the share of the more expensive polymer in the product. These are batches of greater mass and a somewhat different character than the highly concentrated dyes, but still in the typical granulate form.

The boundary between these groups is sometimes fluid. Many real concentrates combine functions — a colouring masterbatch may at the same time carry a UV-stabilising additive, and a black concentrate often plays the dual role of pigment and light protection. From the logistics point of view, however, this division matters less than the physical character of the load: batch size, intensity of colour and sensitivity to contamination. It is these three features that determine the handling method at the terminal, regardless of the formal category of the concentrate.

Physical form and dosing

Masterbatch is supplied in the form of granulate with a grain size most often about 2-4 mm, visually close to the base plastics. Colour, white and black masterbatches are sometimes intensely coloured and highly opaque, but the grain size and flowability remain comparable to virgin granulate. This conformity of form is deliberate: it ensures easy, accurate and repeatable dosing on the processing line, whether by weight (gravimetric dosers) or by volume.

The essence of a concentrate is the high concentration of the active ingredient. The pigment or additive occurs in the masterbatch at a share many times higher than the target in the product, so it is enough to add a small percentage of concentrate to achieve the intended effect. This translates directly into logistics: masterbatch batches are usually smaller than base-granulate batches, because each tonne of finished plastic requires only a few dozen kilograms of concentrate.

Smaller batches mean that masterbatch more often travels in big bags (FIBC) and 25 kg sacks than in bulk. Bulk transport in silo tankers happens with large, uniform collections of a single concentrate — e.g. a mass black or white masterbatch for a pipe or film producer — but it is a rarer situation than with virgin granulate.

Dosing accuracy is here an economic and a quality matter at once. Because the concentrate is expensive per kilogram, while acting in a small share, processors use precise gravimetric dosers that maintain the set proportion to tenths of a percent. Too little additive gives weak, non-uniform colouring or insufficient protection; too much is a loss of costly material and sometimes a deterioration of the product’s mechanical properties. The form of even, clean granulate — without a dusting fraction and without sticking grains — is a condition for such dosing to work repeatably at all. This is another reason why gentle transfer and grain-quality control have real significance with masterbatch.

Producers and the market

Masterbatch is made both by large chemical corporations and by specialised compounding companies that produce “made-to-measure” concentrates for a customer’s specific applications and shades. The market is strongly globalised: a large part of concentrates circulates within the plastics-industry supply chains between Asia and Europe and within Europe itself, which is why masterbatch appears in the same container flows as imported granulate.

For an inland terminal the practical conclusion is important: masterbatch rarely travels on its own as a separate stream. Most often it accompanies the base granulate — a processor receiving PE or PP simultaneously brings in colour and additive concentrates for its production. For this reason we handle these materials together, in one collection rhythm, which simplifies planning but raises the requirements for batch separation and cleanliness.

Storage and sensitivity to conditions

Masterbatch is stored under dry and clean conditions, in tight big bags or sacks, under a roof and on a dry surface. Although the carrier is a thermoplastic, some concentrates are more sensitive to ambient conditions than pure base granulate. Some additive masterbatches contain hygroscopic or temperature-sensitive additives, so producers give recommendations on maximum moisture and storage time, and some concentrates require pre-drying before processing.

At the terminal what matters above all is preserving the integrity of the packaging and the traceability of the batch. Colour concentrates of different shades look similar from the outside, and confusing a batch or losing the marking is a real quality risk — hence the discipline of labelling and separation at every buffering stage. Sensitive white and light concentrates we keep away from dusting and dark materials, so that stray dust does not lower their cleanliness. This is an extension of the general principles of bulk material storage with an order regime proper to products with a strong effect in a small share.

ADR classification

A typical masterbatch in the form of polymer granulate is not classified as a dangerous good and is not subject to ADR regulations. The pigment or additive is permanently embedded in the polymer carrier, so the material behaves in transport like an ordinary plastic granulate — non-ADR, without marking and dangerous-goods transport documentation.

As always with chemical materials, however, the principle of caution applies. Some additive masterbatches with a high concentration of specific additives may have separate requirements arising from the nature of the additive itself. That is why, when accepting a load, we verify the status in the safety data sheet of the specific batch, rather than assuming it in advance. As standard, masterbatch fits into our basic stream of bulk materials — alongside PE, PP, ABS, PS, PA, PVC, PET and other plastics — as a non-ADR material.

Transloading cleanliness — the most important thing

With masterbatch, the cleanliness of the stream is not a formality but the core of handling. It is a product with a strong effect in a small share: a few percent of concentrate decides the colour or properties of the whole product batch. Any contamination with foreign material — especially another, coloured concentrate — is immediately visible in the finished product and disqualifies the load.

Imagine a few grains of black masterbatch that, with careless transfer, reach a batch of white concentrate or a light granulate for transparent film. The result is visible dark specks in the product and a complaint about the whole delivery. That is why between batches and colours we maintain a cleanliness regime comparable to handling the most sensitive granulates, described more broadly under the topic of cross-contamination.

In practice this means: cleaning the transfer path and equipment between batches, unambiguous traceability of every batch, separating coloured concentrates from light materials, and controlling the stream with cleaning sieves, which catch foreign grains and contaminants. With colour masterbatch an additional order discipline applies — we do not allow coloured dust or a single grain to wander between stations.

Transloading masterbatch at the terminal

In terms of transfer mechanics masterbatch behaves like a plastic granulate, so we handle it by the pneumatics-free method: a gentle, gravity-fed flow from big bags through a sieve into a silo tanker or back into sacks, without pneumatic conveying. Thanks to this we do not damage the grain, do not generate excess dust and do not disturb the uniformity of the concentrate.

At the terminal in Chorula, with a buffer warehouse of up to 2000 big bags, we most often handle masterbatch in parallel with the base granulate, in the customer’s collection rhythm. The difference from ordinary granulate lies not in the technique but in the organisation: we watch over batch and colour separation, document traceability and do not allow streams to mix. This is the same logic of bulk material storage that we apply to all sensitive loads, raised by the rigour of colour cleanliness.

The full transloading offering we describe on the big bag to silo tanker transloading page, and a broader context of bulk material transport can be found on the PHS Magnum portal. Masterbatch, as a non-ADR material in granulate form, fits into the standard stream we handle — everything that pours well and is not a dangerous good.

Related topics

Masterbatch is best understood as “additive granulate” that flows through the same stream as the base plastics — PE and PP — and is handled almost identically, only with a raised rigour of cleanliness. Its types link with other encyclopaedia topics: black masterbatch with carbon black, additive masterbatch with plastic additives. The transport forms remain big bags (FIBC) and sacks, and the core of safe handling — pneumatics-free transloading and control of cross-contamination.

Sources

• Technical materials and safety data sheets of masterbatch and colour-concentrate producers.
• Industry guidelines on plastic colouring and concentrate dosing in injection and extrusion processing.
• Operational practice of the SMIALA terminal, Chorula — Aleksy Pasternak.