Comparative study of degradation between the carbon black back coat layer and magnetic layer in magnetic audio tapes using attenuated total reflectance Fourier transform infrared spectroscopy and machine learning techniques

Abstract

AbstractMost magnetic audio tapes in the industry were initially made with only two layers, the base film with polyethylene terephthalate (PET) and the binder layer with polyester polyurethane (PEU). The binder layer seems to undergo degradation from hydrolysis, causing the condition “sticky shed syndrome (SSS).” Hydrolysis is a reversible reaction where atmospheric moisture reacts with weak ester bonds to form degradation products, alcohols, and carboxylic acids, which produce sticky materials, hindering the playability of tapes. Later, another layer called “back coat” was introduced to magnetic audio tapes. This layer consists of carbon black embedded in PEU or polyether polyurethane. Carbon black particles in this layer absorb water, facilitate high‐speed tape winding, and remove static electricity charges. However, due to the ability to absorb water, hydrolysis can occur in the back coat layer as well. For this reason, there is a study claiming that the back coat is responsible for the degradation of magnetic audio tapes, and by removing it, SSS can be overcome. To test the validity of the above claim, this study uses attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT‐IR) with multivariate statistics to determine the degradation of the back coat layer and compare the results with the magnetic layer of the same tape identities. Results obtained show poor predictability in the back coat test set when compared with the results collected from the magnetic side, which indicates that to determine the playability status of this specific magnetic audio tape collection, the preferred side to obtain spectra is the magnetic layer.