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Talc in Plastics

Talc is a highly functional additive that enhances key properties of numerous resins. In addition to being a cost-effective filler, talc can effectively provide antiblocking, reinforcement, and improved barrier properties. During polymer processing, talc, as the softest mineral, minimizes equipment wear. It also decreases mold shrinkage, and improves end product machining.


Uses For Talc In Plastics
Plastics exhibit increased stiffness, reduced mold shrinkage, improved heat stability and lower material costs when filled with the appropriately sized talc. Impact strength can be maintained when the particle size is carefully controlled to a 1 to 2 micron, ultrafine median particle size while maintaining a minimum top size. In addition to size, talc particle shape and particle aspect ratio can be used to further optimize these properties. Talc-filled polypropylene automotive parts, whether they are interior, exterior or under the hood applications, have the required stiffness, strength and other mechanical properties. Talc-filled polypropylene works well in appliance applications requiring load-bearing properties at ambient and elevated temperatures.  

Thermoplastic elastomers, whether they be homopolymer, copolymer or TPO resin systems, benefit from the addition of the appropriately sized, high aspect ratio talc. Talc filled olefins also exhibit ductile fracture while the base resin fractures tend to be brittle.   

As an example, talc with an aspect ratio of 10 to 1 when melt compounded with a homopolymer will provide a 250 percent increase in flexural modulus.

In polyethylene film applications, talc is an effective, low abrasion antiblock. Polyester gel coat barrier properties are improved with the addition of fine ground, platy talc. Talc also functions well as a nucleating agent during melt compounding. 

Some of the key plastic application areas for talc are:

  • Anti-block in
    • LLDPE, LDPE, & PP Films
  • Barrier in
    • BMC, Polyester Gel Coats
  • Reinforcement in
    • Polypropylene
    • TPOs/TPEs
    • HDPE
    • Nylon
    • Epoxy
    • Phenolics
  • Nucleation agent in
    • Nylon
    • Polyolefins


Specialty Minerals Talcs in Plastics
A variety of talcs are manufactured by Specialty Minerals to suit the formulator’s need to optimize the properties of a particular polymer system for a particular application. FlexTalc® talc products are ideal for the high performance automotive TPOs for interior and exterior applications. FlexTalc 610, an ultrafine 1 micron talc, provides the best performance. These high brightness products provide increased stiffness, i.e., improve the flexural modulus, improve the heat deflection temperature and the tensile strength of the base polymer. For the same high mechanical performance, but where high brightness is not essential, the Barretts, Montana, MicroTuff® AG talc series offers a cost-effective alternative. When mechanical demands are less, but brightness is still critical, the Mt. Vernon, Indiana, MicroTuff® 9100 talc series are recommended.

Specialty Minerals was the developer of talc-based antiblock additives for polyethylene films.  ABT® and Polybloc® talcs are best suited for general purpose blown films. When the highest clarity is required, the Optibloc® family of products should be used.

For nucleation, use an ultrafine ground talc such as UltraTalc® 609 talc. This and slightly coarser products act as nucleation centers, increasing the temperature at which the polymer crystallizes and solidifies, thereby reducing cycle time and increasing productivity.

 

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