Talc in Automotive Industry

With the evolution in the automotive industry, the amount of plastic part in manufacturing of cars was also increased. Since 1950s, plastic materials were used in automobile manufacturing. In fact, use of plastic components was developed when advanced processing systems and tools became available to engineers. Due to the fact that Talc increases the hardness of the product, it is known as an excellent filler in the automotive industry. The finer the Talc is, the higher the stiffness will result in the polymeric composites, which reduces the weight without interfering with the performance of the product. In fact, most plastic parts of cars are composite materials. The application of thermoplastics, which is filled with Talc, can be ranked according to the final destination; such as the interior, exteriors and under the hood. For example, in the interior, the instrument panel, the door panel, pillar covers, consoles, seat backs, head liners, it is commonly made with Talc filled polypropylene. It should be noted that features like appearance and resistance to scratches and abrasion in the long run are also required. All of these parts are painted to fulfill car body aesthetic.

For under hood, composite filled with this mineral is also used. For this part, good thermal property is considered. The newest and latest available polymer grades, modified by talc (polypropylene based materials), are mostly used for the interior. This progress was made in the automotive industry with the continuous improvement of the polymeric materials enhanced and processed with this mineral. fillers are defined as materials that are added to the (plastic) formulation to lower the compound cost. In such situation, fillers are used as extenders; but extenders generally provide minor mechanical improvements (or some properties degradation). When, using filling materials, certain properties variations are requested, functional fillers must be used. A filler can be considered as “functional” when a certain property will result better in the final composite than in the unfilled material. A typical mechanical property enhanced with functional fillers is rigidity: by adding a functional filler to a certain polymeric matrix, a significant variation in stiffness can be obtained.

Talc is generally considered a functional material because it is able to modify significantly some properties in modified polymeric matrix, when properly dispersed. Talc is normally used to modify several polymeric matrixes used in automobile production. Whenever a stiffness increase is required in combination with good aesthetic and dimensional stability, talc is used. Besides polypropylene, talc is also used in polyamides, polyesters and other thermoplastic polymers. Talc is introduced into thermoplastic materials during a specific processing step, generally known as compounding. During such phase, also other modifiers (Pigments, impact modifiers, stabilizers, lubricants) are introduced into the final product. Compounded material, in pellet form is then transformed through an injection molding machine (or other shaping equipment’s) into the final item and assembled for final application. In fact, most of plastic parts used in automobile construction are composite products.

Main car applications where talc filled thermoplastics are used can be ranked according to the final destination as: interiors, exteriors and under the hood. In interiors, instrument panels, door panels, arm rests, pillar covers, consoles, seat backs, head liners, mirror housings are normally made with talc filled polypropylene. For most of these grades a good aesthetic associated with high mechanical resistance is required. Additionally, scratch resistance for long term appearance is also required. In general materials for interiors must be stabilized to resist too high temperature and UV irradiation. Main exteriors applications are represented by bumper fascia, rocker panels and grills. For all these applications a strong impact resistance and a very low thermal expansion is required to be jointed with metal parts having a very low dimensional variation with temperature. Most of these items are painted to match car body aesthetic.