Talc in Plastic Industry




Plastic is a polymeric material that has the capability of being molded or shaped, usually by the application of heat and pressure. This property of plasticity, often found in combination with other special properties such as low density, low electrical conductivity, transparency, and toughness, allows plastics to be made into a great variety of products. The most commonly used additives in different types plastic materials are: plasticizers, flame retardants, antioxidants, acid scavengers, light and heat stabilizers, lubricants, pigments, antistatic agents, slip compounds and thermal stabilizers. While a large range of minerals are used in plastics, a handful of minerals account for most of the mineral usage in plastics: calcium carbonate, talc, kaolin, wollastonite and mica. Conversely, the addition of talc can be much more effective in heat resistance.






It can be said that Talc fillers cause the following changes in plastics:


• Density increase
• Increased printing and bending values with E module
• Improvement of surface hardness and quality
• Decrease in the heat effect of mechanical values
• Cost reduction.

Talc allows the following changes in plastics:


• Ease of use of plastics
• Printing and forming times are shortened
• More heat resistance
• It is possible to meet the dimensions, the depressions are reduced
• Creep problems are eliminated
• Reduced tendency to release itself under load
• Better bending and impact values






The use of filled reinforced plastics are increasing rapidly. Although some special fillers also increase, 50% calcite is still preferred in filled plastics. The greatest increase in addition to calcite is observed in talc, because it gives toughness and provides smoothness. The excessive increase in oil prices causes the cost of plastic materials which are the source of petroleum and the cheapness provided with fillers becomes more important. With the new research and development efforts, filler types and their compatibility with plastics are investigated and solutions are sought with higher fill rates. These researches aim at the both cheapness and superior quality with new fillers, new resins and easer mixing methods. Talc increases gliding properties for improved surface appearance without sacrificing mechanical properties. Moreover, its water repellent characteristics make it an effective desiccant which further enhances its ability to reduce the cost of producing plastic items with high-performance fillers.








Polystyrene resin (PS)

Polystyrene resin has shortcomings such as high brittleness and sensitivity to environmental stress cracking. After adding talc, it can adjust rheological properties, improve impact toughness, increase perturbation modulus, and increase tensile yield strength. For example: adding 40% superfine talc powder or talc powder masterbatch, the perturbation modulus increases from 23800kg/cm2 to 58800kg/cm2, and the tensile strength increases from 336kg/cm2 to 385kg/cm2.

Polyvinyl chloride resin (PVC)

The average particle size is 5 microns or 2000 mesh talc. After adding to 40-45% volume, the yield strength is even higher than the original breaking strength, which has a significant enhancement effect on the PVC system; the unnotched impact strength is 15% by weight There is basically no reduction in the weight, and the notched impact strength is reduced; it can significantly increase the flexural modulus.








Polystyrene resin (PS)

Polystyrene resin has shortcomings such as high brittleness and sensitivity to environmental stress cracking. After adding talc, it can adjust rheological properties, improve impact toughness, increase perturbation modulus, and increase tensile yield strength. For example: adding 40% superfine talc powder or talc powder masterbatch, the perturbation modulus increases from 23800kg/cm2 to 58800kg/cm2, and the tensile strength increases from 336kg/cm2 to 385kg/cm2.

Polyvinyl chloride resin (PVC)

The average particle size is 5 microns or 2000 mesh talc. After adding to 40-45% volume, the yield strength is even higher than the original breaking strength, which has a significant enhancement effect on the PVC system; the unnotched impact strength is 15% by weight There is basically no reduction in the weight, and the notched impact strength is reduced; it can significantly increase the flexural modulus.






The influence of talcum powder on plastic properties


• Improve the molding shrinkage rate of plastic products as the content of talc powder increases, the shrinkage rate of polypropylene plastics gradually decreases. The addition of talc powder increases its viscosity and decreases creep properties, thus reducing the crystallinity of the plastic; talc powder itself has no shrinkage, thus Reduce the overall material molding shrinkage.

• Surface hardness and surface scratch resistance Surface hardness and surface scratch resistance are requirements for certain plastic products. Adding talc to polyethylene and polypropylene plastics can effectively improve the surface hardness and surface scratch resistance of products.

• Flexural modulus the addition of white talc with flake structure to any kind of plastic can significantly increase its flexural modulus. For general mineral filling, this is the most significant feature of talc. Tensile Strength The content of talc powder within a certain range can increase the tensile strength. After adding 1500 mesh activated talc to polypropylene, the tensile strength of the material changes. When the content of talc powder is less than 20%, the tensile strength of the material increases slightly. When the content of talc powder is above 20%, the tensile strength of the material gradually decreases as the content increases. The main reason is that the talc powder further increases, which weakens the polypropylene. Caused by the intermolecular gravitation.

• Impact strength the effect of talc on the impact strength of plastic materials is similar to the effect of talc on the tensile strength of plastic materials. When the content of various mineral additives is less than 10%, they all have an effect on improving the impact toughness. When the content is greater than 10%, the impact performance begins to decrease.

• Deformation temperature Talc has a significant effect on the thermal deformation temperature of plastic materials, and can effectively increase the thermal deformation temperature of various plastics, thereby increasing the heat resistance of plastics.





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