Liquid Color Benefits for Plastics Processors

Due to the flowable nature of liquid products, you can pump the material to several different possible entry points.

You can dose into a blender if any premixing is necessary; you can dose directly into the throat through an adapter tube that can bring your dosing within 0.5 inches [1.27cm] of the screw; or you even have the ability to dose downline on the barrel of the extruder either through a vent hold or a manually drilled hold depending on desired location.

Liquid color and additives begin to disperse as soon as they are introduced to the material in the process, whereas other forms of colorant and additives rely heavily on heat and shear pressure to disperse fully. This can lead to better dispersion in the finished part when using liquid and also lends itself to the possibility of dosing further down the barrel for faster color changes. However, finding the dosing location that gives you the best combination of strength and dispersion along with shortest changeover and cleanout times is key.

With the Riverdale Gravimetric System (RGS) and Pump In A Drum (PIAD) technology, dosing is simple. Only electrical power and an air supply is needed to run the RGS dosing units. No calibration is required – an operator simply enters the let-down ratio of the liquid material, the throughput of the extruder (in lbs/h or kg/h), and the density of the liquid material (which can be found on the label of the pail/drum). The RGS also has the ability to run in continuous or extrusion following mode (where dosing is determined by the speed of the screw).

Optimal applications for liquids include production of pre-colored compounds and incorporation of highly concentrated additives at low let-down ratios.

Plastics processors handling recycled feedstocks may also benefit from the +Restore additive, which restores physical properties when using post-consumer recyclate (PCR) or regrind. +Restore has been shown to improve the physical properties of regrind to within 99% of virgin. It also ensures better flowing resin that is easier to process and has been shown to increase part consistency in injection molded applications.

Riverdale Global supplies several plastics processors who report that the use of liquid color technology allows them to make faster adjustments on-the-fly, and results in less build-up on the screw and easier management of raw materials. They are also cleaner, safer and easier to use than straight power pigments.