Everything you need to know about Masterbatches
3 Mar, 2023
Plastic has taken up every possible role in the consumer & industrial market, be it FMCG, White Goods, Medical or the Automotive segment, but can plastic alone, in its raw form, be this versatile and meet the varied expectations from such a diversified range of applications? The answer is no. It requires supporting additives to give it the shape, color and have the desired characteristics so that the end product meets the intended functional requirements. This role is accomplished by addition of masterbatches / filler compounds. It is one of the most economical ways for coloring and adding various additives to the base polymer during various plastic processing operations such as Injection Moulding, Blow Moulding, Extrusion, etc.
Essentially, Masterbatch is a supplementary ingredient that is added to plastic polymers to impart properties such as color, coloring effects, strength, fire retardant properties and other traits. The Masterbatches / filler compounds have a base polymer in which a high concentration of pigments / additives is embedded during compounding which essentially involves extruding and granulating the mix so as to get the granules.
How are masterbatches made?
It is important to understand that masterbatches are different from plastics in the way that plastics are complex and long chains of polymers, while masterbatches are simple polymers or resins along with very high concentrations of desired chemicals. These are highly concentrated mixtures of pigments and additives that are added during final plastic processing in the required proportions.
Masterbatches are made using either simple polymers like high density polyethylene (HDPE) or more complex carbon-fiber composites. Manufacturers are normally tailored and manufactured as per customer specific requirements and involve the following steps:
- Mixing: The polymers, additives, chemicals are mixed to get a homogenous consistency.
- Extrusion: Polymers undergo the extrusion process, where they're heated and passed through smaller apertures in extruders. The pigments and additives are added over time to the mixture in specific dosages to get the desired properties.
- Wetting: To avoid clumping and even dispersion of the pigments, the mixture is moistened periodically.
- Cooling: The mixture is then cooled off completely and passed through a pelletizer or pulverizer to make granules, pellets, or powder as per the requirements. In certain cases the Masterbatches may be supplied in liquid form also (Pigments used for Coloring PET Preforms.
- Later, the mixture is packaged to be stored or transported conveniently.
Different Types of Masterbatches
Masterbatches are classified depending upon the final application.
- White Masterbatch: White concentrates make the plastic opaque due to its Titanium Oxide content, which has the ability to scatter light and thus make the object appear opaque. It has many applications, such as lamination, protective filming, coating, pipes, thermo-forming, fibers, and primarily in blow moulded and injection moulded plastic components.
- Black Masterbatch: It is a very cost effective method to impart certain features like UV protection, conductivity and color with good performance by using carbon black to generate the black color in plastics. The carbon black gives a range of tones, from alcohol blue to warm brown. It makes the plastic durable and resistant to extreme weather. It has multiple applications in the plastic and engineering industries like laminated tarpaulin, PE films, telecom duct pipes, HDPE pipes for agriculture, PP fibers and filaments, and Roto Moulded tanks.
- Color Masterbatch: Color concentrates are used to impart color effects to the plastic. It can be specific to the brand's specifications, or used to create a specific effect like marble, glitter, metallic, granite, wood, fluorescent effect, etc. These masterbatches find wide uses across industries and consumer products, for instance, in home appliances, toys, CDs, cosmetic bottles, plastic furniture, textiles, etc. Apart from color, these also provide thermal stability to the plastic products.
- Additive Masterbatches: These are added to the plastic to improve its heat resistance, impart fire retardant properties, provide slippage, anti bacterial properties, etc. By virtue of the additives added, the polymer becomes more heat conductive, takes less time to melt and cool off and has improved stability to sustain heat and shearing during processing. It becomes more rigid and durable and less susceptible to oxidation or UV exposure. These additives can be very specific in terms of their function, like optical brightener, flame retardant, UV stabilizer, anti static agent, PP clarifying agent, blowing agent, anti-oxidant, etc. These type of additive masterbatches find application in practically all applications wherein polymers are used like packaging, consumer goods, automotive, building and construction, agricultural equipment, etc.
- Filler Masterbatches: It is a compound of CaCO3, Talc, Glass Fibres, speciality compounds like Molybdeum di Sulphide, etc and primary plastic resin plus other additives as per customer specific requirements. Primary plastic polymers are costly and non-biodegradable. Filler masterbatches are mixed with the primary polymers to increase their range of functionality, cost-effectiveness, improve productivity, etc. CaCO3 fillers increase the rigidity and plasticity of the end product. Cost effective CaCO3 masterbatches find use in the production of ceiling panels, plastic frames, plastic doors, PVC pipes, electrical cables, films, fibers, blow moulding and injection moulding.
Why choose masterbatches?
Masterbatches are one of the most convenient methods to add a desired property to a polymer / plastic product. It has a lot of advantages over concentrated pigments or additives while adding to the final product.
- Ease of blending additives: Since the masterbatches are premixed with carrier resins and additives of known concentration in the form of pallets or granules, it becomes easier to incorporate them directly into the polymer mixture without any specialized dosing equipment.
- Accuracy of Additives: The masterbatches have a predetermined percentage of dosage, therefore, calculating the amount to be added to the polymer is simpler and does not require much precision. Also, it reduces the chances of variation during the manufacturing of products over course of time.
- Better product consistency: Because masterbatches and polymers have similar physical properties, they easily blend together, giving the product a consistent color, opacity, or other characteristic. Due to uniform dispersion of additives, the complete manufacturing lot has the same characteristics, minimizing rejections and saving on cost.
- Safely Managing Hazardous Materials: Masterbatches are convenient and safe to handle since the additives or pigments are embedded into the inert resins. There is no chance of an airborne hazard, as well as no dust or powder spills, which could be a danger to both the environment and humans. Thus, requiring no specialized safety equipment or gear.
- Easy Handling of Material: Masterbatches are also easy to handle, store, and transport, with no risk of spills or dust accumulations on the surfaces. As a result, there is no cross-contamination, cleaner work floors, and a quick transition to different production lines.
- Better shelf life: Once the additives are encapsulated in the resins, they lose their reactivity and become stable. Also, they are less affected by external factors like temperature, humidity, and UV exposure, thus increasing their stability and shelf life.
Masterbatches are simple compounds with exceptional qualities, which make the manufacturing process a lot simpler, cost-effective and much more efficient. With the reduction in complicated procedures, handling equipment, and the dire need of accuracy, manufacturers can achieve higher levels of quality, consistency, and reliability in their final products with better productivity.
Due to the materbatches, polymers have been used to manufacture a diverse range of products for varied applications thus improving the overall quality of life of human beings and making many products easily available at affordable prices.
