Solvent cast technology – a versatile tool for thin film production

From the end of the 19th century, the development of a process for manufacturing thin plastic films was tightly linked to the emerging industry for movies and photographic films. 5 mil (125 micron) film was produced using a discontinuous device with a caster moving over 200 feet long glass plates at Eastman KODAK [1]. Soon, first patents were issued to cast celluloid films on a moving surface by the ‘‘Celluloid Company’’ in the United States and patented in 1896 [2]. For economic reasons, Eastman KODAK developed a continuous casting process parallel to the Celluloid Company, resulting in a patent infringement. KODAK switched over from the discontinuous to the continuous casting process about 5 years later. At that time, photographic film base was produced from cellulose nitrate and campher as a plasticizer from solutions in solvents such as acetone, ether and alcohol on wheels with diameters of 9 feet ( 21⁄2 meters) at a maximum speed of approx. 150 feet/h (50 m/h). That translates into about 50 square meters / hour. The knowhow required to manufacture highly stable huge steel wheels with perfectly polished surfaces was perfected by the Eastman KODAKCompany over the next 100 years. It was an interesting ‘‘switch’’ in industrial history, that the competing European film companies started some years later with belt casting technology and even now both manufacturing processes still run parallel in the US and elsewhere. The use of an endless flexible belt seemed to offer certain advantages in terms of process speed. On the other hand, the technology needed to produce belts with a uniform thickness, invisible joints and polished surface was not very far developed in the early 20th century. Progr Colloid Polym Sci (2005) 130: 1–14 DOI 10.1007/b107336 Published online: 3 June 2005 Springer-Verlag 2005