Solvent Extraction Methods for NonFibrous Additives in Spun Yarns
Solvent extraction isolates spin finishes and waxes from spun yarns, preventing excess processing aids from inflating commercial mass and landed duty costs.
Soxtec Method
Extraction Protocol
Automated laboratory procedure used to determine the total fat or oil content in a solid sample through continuous solvent washing. The soxtec method improves upon older techniques by combining boiling, rinsing and solvent recovery into a faster, integrated process. It is the preferred standard for checking the oil content of yarn or the finish level on synthetic fibres.
Operational Sequence
Testing involves placing a weighed sample into a porous thimble which is then submerged in a boiling solvent for a fixed period. During the soxtec method, the solvent extracts the soluble matter before the thimble is lifted for a final rinse with fresh condensed solvent. This two-stage approach ensures that the extraction is complete in a fraction of the time required by a traditional extractor.
Finally, the solvent is evaporated and the extracted residue is weighed to determine the percentage of matter removed. High-temperature boiling significantly accelerates the dissolution of stubborn waxes and synthetic polymers.
Solvent Recovery
Automation allows for the capture of a high percentage of the chemical agent for reuse. This reduction in solvent waste lowers the cost per test and limits the exposure of laboratory staff to harmful vapours.
Sample Constraint
Accuracy depends on the sample being finely divided to allow the solvent to reach all surfaces. The soxtec method is only suitable for materials that do not degrade at the boiling point of the chosen solvent.