PCS Liquid Masterbatch Technology

Liquid masterbatch technology has been commercially available in limited markets since the late 60’s/early 70’s for coloring of thermoplastics. However, at the time when liquid masterbatch was introduced as an alternative coloring method, there were many difficulties associated with controlling the dosing of the liquid into the resin being colored. In addition to this, the product was also not fully developed and understood and housekeeping was problematic. These problems resulted in very small markets for the technology and was therefore suited for very specific and limited applications.

Today, with readily available microprocessors to accurately control dosing, and with the extensive research that has been invested into developing the technology, liquid masterbatch technology is becoming more and more popular with end users who are looking to make their production facilities more efficient, streamlined and more economical. The result is that these end users are able to become more relevant and competitive to the market into which they supply. This article discusses liquid masterbatch technology with a brief overview of the technology and information that is important to consider when looking to use liquid masterbatch

What is liquid masterbatch?

Liquid masterbatch is a combination of pigments/dyes and other processing additives that have been dispersed/dissolved in a suitable liquid carrier. The resultant liquid system is designed so that it is compatible with the polymer to be coloured. By dispersing/dissolving the ingredients into a liquid, higher concentrations of pigments/dyes can be added to the carrier system compared to granular masterbatches therefore reducing dose rates. In some cases, does rates can be lower than 0.05%.

How is liquid masterbatch introduced into the polymer?

Referring to the below figure, the liquid masterbatch is introduced into the polymer by means of a pumping system. The pumping system is controlled by a microprocessor that ensures accurate and consistent dosing. The liquid is stored inside a container/reservoir and then pumped directly into the injection/extrusion machine at the feed throat of the machine under the hopper. With production running, the user is able to start, adjust or stop the colour without stopping the injection/extrusion machine or changing the contents of the hopper. As the polymer resin flows from the hopper into the injection/extrusion machine, the required amount of liquid is added to the resin at that instant the resin enters the feed throat of the machine therefore keeping the material in the hopper colour free until it enters the injection/extrusion machine for processing. This also eliminates the requirement of having mixing equipment such as high speed mixers to mix the masterbatch uniformly into the resin.

Schematic of liquid masterbatch coloring setup.

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