Common fillers used in injection molding

Injection molding in plastic manufacturing is a process to form concrete parts by injecting molten polymers into a specially-designed mold. Host material (thermoplastic and thermosetting polymers) is transferred into a barrel where it could be heated, mixed with fillers and forced into a mold. The plastic is then let cooled down within the mold then released in a concrete shape.

There are several types of fillers and additives commonly used in plastic injection molding. They are usually classified according to six functions.

Filler to adjust rigidity

Glass fiber, carbon fibers and talc fibers are used to enhance the rigidity of plastic. Among these reinforcement materials, the most common one is glass fiber. Normally, coating materials are added to clad the mechanical bonding between the fibers and the polymer matrix, resulting in a more rigid plastic material.

Glass fiber to reinforce polymer structure

On the other hand, plasticizers (also known as dispersants) seeks to decrease the viscosity of plastic material. These are often liquids added to lower the connection between polymer chains. As a result, it enhances their flexibility and plasticity. They are widely used in manufacturing PVC pipe. In 2014, the global plasticizers market reached a total of 8.4 million metric tons.

Filler to reduce cost

CaCO3 filler to reduce cost

The most common cost-reducing filler for plastic comes from CaCO3 (Calcium Carbonate). According to Plastic Technology, CaC03 filler has become the rule for survivor. Climbing resin prices, heavy tariff and strict competition, firms are turning to increase their stock of mineral filler. More Filler, Less Resin has become the solution for plastic bag producers or other plastic sectors prioritize cost value.

Filler to improve processing

Mold release agent is necessary to operate injection molding process

Mold release (release agent) and lubricants also go hand in hand with the activation process of injection molding. The injection process often operates under high pressure, therefore mold entrance and cavity needs to be coated with a purposed mold release agent. Engineers also ensure to apply lubricant to maintain the quality of mechanical parts.

Filler for special application purpose

UV stabilizers added into the host material

There are several material used as specialized filler but two categories receive most attention: flame retardants and UV stabilizers. Manufacturers add flame retardants agent into polymers to reduce the flammability rate and smoke formation potential rate. Meanwhile, UV stabilizers clad plastic material from sun exposure and increase the resistance of plastic product. UV stabilizers are extremely important in plastic film manufacturing.

Filler for appearance

Colored Masterbatch

These are often called masterbatch or concentrate, a method to mix pigment into resin. The market for masterbatch is thriving in Asia, which accounts for 46% global production. There are three types of masterbatch categorized by the most popular shades: white, black and colored masterbatch.

About Polyfill

We are Vietnam’s leading provider of filler masterbatch and masterbatch. With the enormous CaCO3 resource in Vietnam, we offer the most cost-effective filler masterbatch at the best quality. Our factory is located near the seaport of the Hai Phong Industrial Province, an ideal location to deliver our pacels oversea.


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