| In the field of synthetic fiber, although a lot of gray silk with hollow structure were developed, it has been very hard to make natural fiber with hollow structure by techniques. Hollow material has been a controller of synthetic fiber. Producing hollow cotton yarn mainly utilizes water soluble PVA fiber and a PVA yarn is used as the core and cotton fibers form the sheath and then form cotton/PVA core-spun yam. The water soluble PVA in the center is removed from the yarn structure in the boiling water with a good extraction of more than 90%. "Hollow " yarns have the properties with light-weight, flexible and more warm, even if they were laundered several times, they can maintain soft style.In this paper, we produced " ZZ " and " SZ " core-spun yarns ,and then get hollow cotton yarn through removing PVA fiber. We have analyzed and tested the properties of them and their fabric to meet the need of industrialized production of hollow cotton yarn. Some conclusions had been drawn:1.Through simple modifying ASS 11 ring spinning frame, a cotton/PVA core-spun yarns with " ZZ ", " SZ " direction of twist can be made and the sheath fiber hide the core completely. The PVA yam as the core and the cotton fiber as the sheath are interlaced, which is helpful to set the boiled hollow yarn. The factors that affects the coverage for core are core coverage, tension, gauge, pipe socket, traveler and the position of the core yam for feeding.2.The factors that affects removability of PVA in core-spun yam and their fabric are the soluble temperature of water soluble PVA fiber, water temperature-, the twist multiplier of the core and the core-spun yarn, the percentage of the core, the structure of fabric. The best removing time is about 30 minutes for " SZ " core-spun yarn and 40 minutes for "ZZ" core-spun yarn.3.Through removing experiment of the core-spun yam, we find some factors that affects hollow effects of the hollow cotton yam, as follows: the kind of PVA fiber, the twist and direction of twist of the core, the twist of the core-spun yarn, the percentage of the core, the core coverage of the core-spun yam.4.The strength experiment of the yarn indicates that the strength of yarn appears up and down fluctuating curve with the boiling time going. After PVA fiber is removed entirely, the strength tends to stabilization. Compared with "SZ" strength curve , " ZZ " strength curve postpones totally. Attaining the highest strength " SZ " takes less boiling time .So in the condition of the same experiment we should choose" SZ " core-spun yam for making hollow cotton yam.5.The weight of loss experiment of the core-spun yarn indicates the extraction of PVA is more than 90%,but as for "SZ" and "ZZ "core-spun yarns with the same tex, same percentage of the core, the extraction of PVA of former is higher than that of later.6.From the twist experiment we can see that the true twist of the core of " SZ " core-spun yarn is twice than their primary twist and the twist of the core of " ZZ " core-spun yarn decreases one multiple.7.The loss of weight experiment of fabric indicates blending single fabric , "SZ" core-spun single fabric and "ZZ" core-spun single fabric with the same tex , the same percentage of the core, the loss rate of weight is biggest for the blending single fabric, the "SZ" core-spun yarn is the second, the " ZZ " core-spun single fabric is the last. The loss curves of weight of three kinds of fabric all appears increased and then maintain stable, which also show the removing process of PVA fiber.8.The bursting strength of knit fabric using hollow yarn is lower than using conventional pure cotton yarn, when the boiling time is 40 minutes, the bursting strength of "ZZ" hollow single fabric is 26.8kgf, " SZ " hollow single fabric is 24.0kgf, the blending single fabric is 19.4kgf, the conventional pure cotton single fabric is 36.3kgf.9.Fabric air permeability test indicates the air permeability of knit fabric using hollow yarn is better than using conv... |
