Coating black paint on the door sash of automobiles has been a separate process from the body coating. Recently, moany automotive manufacturers are switching this secondary coating process to adhesive tape technology for various advantages. These advantages include reduction of VOC (volatile organic carbon), rationalization of assembly process, cost reduction and so on. Since this application is considered a variation of exterior decal film, most of the commercially available products are currently based on PVC (Polyvinyl chloride) film. (See Photo 1.)
The automotive industry has increasingly been sensitive to the use of PVC due to its potential environmental problems. One of the problems is that the product cannot be incinerated when disposed of since it generates hydrogen chloride gas, dioxin and other toxic chlorinated organic matters. Also, reportedly its plasticizer may act as an endocrine disruptor (also known as ‘an environmental hormone’) when dissolved in water.
Nitto Denko has developed an environmentally friendly polyolefin door sash tape as an alternative to the PVC tape. By optimizing polymer chemistry and film composition, the new polyolefin door sash tape exhibits high dimension stability in physical properties for a wide range of temperatures. Also, proprietary surface conditioning of this film ensures resistance to long-term outdoor exposure. An acceleration test has proved that the product retains 93% of glossiness compared to that of initial, with colorimetric change (delta E*ab) of only +0.12, for six and half years equivalent of solar ray radiation.
Also, we did not detect toxic gases when we performed incineration tests. Only water vapor, carbon mono-oxide and carbon dioxide were detected in the given detection limit. This test has clearly demonstrated that the product causes significantly lower environmental damage than that of PVC.