Manufacturing of filament
As with cellulose-2.5-acetate in textile applications, the core process in the manufacturing of cellulose acetate yarn is dry spinning using acetone as a solvent. The production of fiber as yarn can be described in three principal steps.
STEP 1: Preparation of the spinning solution
Cellulose acetate flake and acetone are mixed together intensively. If there is a desire to alter the high luster look of bright acetate yarn, Ti02 or pigments can be added to the solution. To achieve a spinning solution free of particles that may block the spinneret holes, the mixing is followed by appropriate filtration.
STEP 2: Spinning
The acetone/cellulose solution is extruded through spinnerets to form individual filaments of the yarn strand. Acetone will be evaporated and to a large degree recovered during this spinning process. The filaments produced during extrusion are brought together at the exit of the extrusion cabinet. The filament bundle is then passed over lubrication devices to apply fiber spin finish, then through an entangling jet to provide strand cohesion just prior to being wound on cardboard tubes.
STEP 3: Packaging
The wound tubes of yarn are packed and prepared for shipping. Yarn properties such as lubricant level and type, entanglement level, and package size are determined for each product to meet customer requirements.