During the production of color and additive masterbatch, compounders face two main processing challenges: particle agglomeration and high equipment torque / back pressure. If not properly addressed these challenges can lead to poor quality masterbatch, low efficiency / output, and damage to expensive processing equipment.
In the manufacture of masterbatch, particle agglomeration is a primary concern. Color and additive masterbatch is typically filled with pigments, minerals, and other additives that have tendency to agglomerate if not properly dispersed. Particle agglomeration leads to reduced color yield and less efficient masterbatch.
Torque & Die Pressure
The high melt viscosity of filled masterbatch are a primary cause of excessive torque and back pressure during manufacturing. This torque and pressure can lead to off quality masterbatch and extended downtimes to fix manufacturing equipment. In addition to machinery wear-and-tear, excessive torque and pressure increase energy consumption and thus the cost of manufacturing operations.
The challenges to masterbatch manufacturing outlined above need to be considered when formulating and optimizing a masterbatch. Improving the dispersion of pigments, fillers, and additives in a masterbatch formulation increases yield and makes for a more efficient end product. Likewise, reducing torque and die pressure can improve output and reduce cost of the manufacturing process. Historically, achieving these two tasks often require tinkering with carrier resin selection and extrusion parameters while also maintaining the desired physical properties of the end product. This can prove to be a daunting task. Luckily, there are additives that can improve both dispersion and extrusion conditions without altering the tensile properties of the end product.
Epolene® Dispersion & Processing Aids
Epolene® is a line of polyethylene and polypropylene polymers that are outstanding dispersing agents and processing aids for masterbatch compounding applications.
To demonstrate the usefulness of Epolene® as a pigment dispersing agent in masterbatch, an independent lab study was performed that compared particle size and distribution of an LLDPE / pigment blue 15:3 masterbatch compounded with and without Epolene®. The microscopy images from the study are below:
The images above show that the addition of Epolene® C-10 to the masterbatch promotes a more homogeneous dispersion with far fewer pigment agglomerations. This improvement in dispersion results in an increase in color yield that allows for less pigment to be used to achieve the desired color. In addition, filter pressure is reduced due to the decrease in agglomerations resulting in more efficient manufacturing runs.
Epolene® has also proven to be extremely useful as a processing aid for highly filled masterbatch. In a separate study, a 50% LLDPE / 50% mineral filler masterbatch was compounded with and without Epolene®. The torque, die pressure, and mechanical properties of the masterbatch were measured.
Average Die Pressure
A 14% reduction in die pressure was observed at a 5% loading of Epolene® C-15 versus the control.
A 28% reduction in torque was observed at 5% loading of Epolene® C-15 versus the control.
The ability of Epolene® to reduce torque and die pressure during compounding results in energy savings and an increase in production rate. Masterbatch is able to be compounded faster with a reducion in power consumption resulting an more efficient and economical process. It is also important to highlight that while compounding pressure and torque were significantly reduced, the tensile properties of the control compared to the Epolene® modified masterbatch remained virtually unchanged.
Selecting an Epolene® Polymer for Compounding
There are various commercially available grades of Epolene® that vary in polymer type, molecular weight, drop point, density, and melt viscosity. Additionally, certain grades of Epolene® are modified with maleic anhydride. These maleated grades are often used as compatibilizers in compounding composites.
*Solid at this temperature. Brookfield viscosity at 190°C = 300 cP
As with any formulation, selection of the proper materials is critical to success. If you would like assitance in selecting the appropriate grade of Epolene® for your application, contact us today to speak with our highly trained team of product experts.