From the view point of environment protection, UNITIKA has developed a completely biodegradable synthetic fiber which causes no pollution by disposal and is compostable.

The main purposes of the development are to find the most suitable melt spinning process and to get enough physical properties for the practical use because the spinnability of biodegradable polymer is poor.

The targets are as follows;

　・ Melting Point : higher than 80℃, preferably 100℃

　・ Tensile Strength : higher than 4 g/d

　・ To clear the relation between the physical properties and biodegradation

It was the point to pay attention to the cooling method and conditions in melt spinning using an aliphatic polyester as a biodegradable polymer.

The problems during the melt spinning process of an aliphatic polyester are basically solved and the tensile strength of the fiber is higher than 4g/d.

Regarding biodegradability, when the degradation of the fiber in soil or in the ocean is observed for a long period, the degradation proceeds from the surface of fiber to the center. It is clear that the degradation rate is related to the surface area of fiber. Also it is turned out that the degradation rate depends greatly on the degree of crystallinity and the orientation of fiber. The earlier stage of degradation is thought to be amorphous phase, the orientation of crystal phase is disordered, and this disordered crystal phase is continuously degraded. The biodegadability is closely connected with the physical properties of fiber.

This biodegradable fiber is expected to be used widely in general living materials, civil engineering materials, agricultural/gardening materials to protect the environment of the earth. Even if left or disposed of after using, this synthetic fiber will be biodegraded by many micro-organisms in soil or in the ocean.