Sizing Agent Selection for Fine Spun Bast Yarns
Optimal fine bast yarn sizing requires balancing PVA and CMC polymers to achieve eleven percent dry add-on without causing warp brittleness.
Sizing Liquor Temperature
Thermal Process Variable
Thermal energy levels maintained in the sizing sow box determine the viscosity, solubility, and penetration of the protective adhesive mixture. Controlling the sizing liquor temperature is essential for ensuring that the starch or synthetic polymers remain fully dissolved and active. This parameter directly affects how well the protective coating adheres to the flax fibres.
Thermal Management
Heat levels in the application bath must be kept within a narrow range to prevent premature gelation of the sizing starch or polymer mixture. If the sizing liquor temperature drops below the target range, the viscosity of the mix increases rapidly, leading to uneven coating and excessive pick-up. High heat levels, on the other hand, can break down the starch molecules, reducing the adhesive strength of the protective film.
Automated steam valves are typically installed to regulate the bath temperature dynamically during continuous runs. This constant adjustment ensures that each metre of flax yarn receives an identical protective treatment.
Yarn Protection
Consistent thermal conditions during the sizing stage produce a uniform, elastic coating that withstands loom tensions. Maintaining the correct sizing liquor temperature prevents the formation of hard crusts or soft spots on the yarn surface. This stability minimizes yarn breakage during fabric manufacture.