Research On Alkali Weight Reduction Properties Of Islands-in-The-Sea Fibers Weft Knitted Fabric

The islands-in-the-sea fiber is a new achievement in the field of synthetic fibers. Because of its particular fiber components and construction, it has excellent softness, drape, air permeability and absorbent quality. As an ideal material for synthetic suede, it shows great developing potentiality.The dissertation puts emphasis on the alkali treatment for the weft knitting fabric made of islands-in-the-sea filaments. Main factors of the alkali treatment are found, relationships between the wearabilities and the alkali weight reduction rate are studied, and the influences the weight reduction velocity does on the fabric are revealed, which makes the function of every individual factor clearer and deepens the understanding of alkali treatment. Besides, the dissertation also does detailed research on the raw material and the heat setting process to make the study more comprehensive and practical.Study on the yarns' properties shows that it's not commended to use the islands-in-the-sea fiber alone but to compound a special kind of highly-contractive polyester yarn to it. Later heating process could make the special fibers contract, tightening the fabric and ensure the fabric quality after alkali treatment. Therefore the heat setting process and its influences on the alkali weight reduction rate is studied. Through the experiment, the best parameter is (190℃, 1min). Fabric's alkali weight reduction rate is slightly different with and without pre-heat setting. It will rise when the heating temperature is below 160℃ and drop over 160℃.Later, the dissertation focuses on the alkali treatment step by step.First, the main alkali treatment factors are studied and found out. It shows that time, temperature, alkali consistency and accelerant consistency are the main effective factors in Alkali treatment, while the bath ratio is comparatively a minor factor. As for the time, The whole weight reduction process is composedof two linear fragments--the "sea" component's dissolving and the "islands"component's dissolving; As for the temperature, the weight reduction is veryslow below 80℃ and turns much faster over that; As for the consistency of the alkali and the accelerant, both will greatly increase the weight reduction whereas when the consistency exceeds a critical value, their influences on the weight reduction will decrease gradually.Then the best alkali weight reduction rate is decided as 23% through the study of relationship between the weight reduction rate and the wearabilities such as strength, elastic recovery, drapery, bulkiness, air permeability and wicking.At last, in order to draft a reasonable alkali treatment process chart, we established the regression equations and based on that deduced the relation between the alkali treatment properties and weight reduction velocity. It shows that the influence velocity has on the fabric is not simple. It's connected with which stage the treatment is at and which way to accelerate the velocity. To accelerate the velocity by increasing the alkali consistency is good to both the evenness of alkali treatment and the fabric strength; There is a critical value to accelerate the velocity by increasing the accelerant consistency, below which increasing accelerate is good to the evenness of alkali treatment and above which it's adverse. Too high accelerant consistency also do harm to fabric's strength; At the early alkali treatment stage, high temperature is not preferable to fabric weight reduction evenness while at the late stage high temperature will contribute largely to it. Low temperature raising velocity is more favorable if there is a temperature raising process in alkali treatment.Based on the analysis above, a reasonable alkali treatment for weft knitting fabric made from islands-in-the-sea filament is designed.