‘The Polyester used by Esterlam is a bi-axially oriented material. The process of stretching the material in the two directions aligns the molecules in the polymer, which creates a much stronger structure with far higher chemical and temperature characteristics.
The melt temperature of Polyester is 240°C compared to 130-170°C for other extruded polymers. While doctor blades rarely reach these temperatures, it does mean that Esterlam blades stays far more stable all the way through the temp curve and offer a much higher working/service temperature.
The same characteristics also apply with chemical resistance. Esterlam blades have a much wider resistance than extruded polymer blades. Esterlam learned this early on when evaluating different doctor blade materials for a myriad of coating and printing applications. This also applies to hot water which sometimes causes softening and buckling with various extruded polymers. Bi-axially oriented Polyester provided the best overall results in stability and longevity.
Another important benefit is spring memory. Polyester is highly crystalized. During the manufacturing process the material is taken to very high temperatures, stretched with enormous energy, and then rapidly cooled. This gives the material excellent ‘spring memory’, (Steel blades are all made from ‘spring’ steel) This spring memory provides more consistent pressure on the anilox roll over a longer period of time and subsequently more consistent ink values.’