Scratch resistance
Polypedia > Defects in polymers
Scratch Resistance | ||
The scratch resistance of polymers can be determined by the scratch test. The graphical resistance of rigid polymers is related to abrasion. In general, the scratch resistance of polymers is proportional to the module. | ||
Current situation: predominant technologies | ||
Improving the scratch resistance of PP and TPO remains a key unmet need in the automotive industry. Current technologies applied include: 1. Anti-slip additives 2. Special fillings 3. Siloxane additives 4. Replace other polymers | ||
Sliding additives | ||
These additives act by lubricating the surface to provide an antiscratch effect and also reduce whitening. However, several disadvantages related to uncontrolled migration: • Exudation on the surface of the pieces • Stickiness after aging / the weather can be a problem • Nebulization (critical for interior applications) • Low paint capacity (partial painting and retouching applications) • Bad adhesion (parts can be joined with adhesives) • The effect is not permanent • The weather is poor • A stronger antiscratch effect is desired | ||
Special fillings | ||
One of the most used fillers is wollastonite. Provides better scratch resistance to TPO. and PP vs talcum. However, Wollastonite has some limitations, for example, • Higher cost vs. talcum powder • It is difficult to incorporate during the composition due to the high aspect ratio (it must be fed down river) • Various grades of wollastonite-filled materials are available. The other commonly used filler is based on Nanoclays. It also provides improved scratch Resistance against talcum but suffers from the following limitations: • Very high cost • It is not yet a mature and commercially viable technology. • Adopted on some low volume platforms to test | ||
Siloxane additives | ||
Like the anti-slip additives, these additives act by lubricating the surface to provide an antiscratch effect and reduce whitening. However, they require higher load levels and have a higher effect price (> 10x) compared to slip additives. Although, these additives are less migratory than landslides, but still have some of the same disadvantages: • Low paint capacity (partial painting and retouching applications) • Bad adhesion (parts can be joined with adhesives) • The effect is not permanent. • A stronger antiscratch effect is desired. • No commercial success to date | ||
Replacing polymers | ||
Plastics such as PVC, PC / ABS and ionomer have superior scratch resistance compared to PP and TPO. These products generally have a higher cost and have lower resistance to weathering than PP and TPO. PC / ABS. Can only be used in interior applications without paint. In addition, PVC is under environmental pressure due to problems with the contamination of the recycled components. |