A Study On The Performance Of The Hydrophilic Polyester Spunlaced Nonwovens And The Entanglement Mechanism Of Fibers During The Hydroentangling Process

The hydroentangling technology is a unique technique in the nonwoven web consolidation process and the basic theory of that is relatively weak due to the relatively short development. The relationship among the materials, forming technology and the product performance is not very clear so far which limited the types of fibers spunlaced process. The hydroentangled nonwovens have be widely used today. Nowadays the main row materials in the spunlaced process are polyester, viscose and some other fibers and the high hydrophilic polyester have be more and more widely used because of its excellent hydrophilicity. Based on such a background, this article puts forward that the study on the performance of the hydroentangled nonwovens and the entanglement mechanism of fibers during the hydroentangling process in order to provide the theory instruction of the new fibers development and produce some multi-functional spunlaced nonwovens with high additional value. This paper based on a large number of literatures review, self-made samples and experiment analysis does the following five aspects: firstly, it analyzes the different performance between the two kinds of polyester fibers and does a research on the carding and spunlaced process. Secondly, it analyzes the structure and performance of the two different PET fibers. Thirdly, it remodels the fiber structure of three-dimension in the spunlaced nonwovens by X-ray tomography analysis and characterizes the 3D structure of the fibers in order to track the fiber trajectory and analyze entanglement situation in the different nonwovens. Fourthly, it analyzes the pulling-out behavior of single fiber from hydroentangled nonwoven in order to reflect the entanglement of the fibers in the spunlaced nonwovens. Finally, it tests the cohesive force of the two different polyester fibers to study the influence factor of fiber entanglement.This paper obtains the following result from the above researches:(1)The fiber length, fineness and the curl degree of the two kinds of polyester fibers is similar and the fiber strength is very close too. The high hydrophilic polyester fiber has the smaller specific resistivity but higher friction coefficient and higher water absorption by the basic properties tests of two different polyester fibers.(2)The thickness of the high hydrophilic polyester spunlaced nonwoven is small and the web uniformity is very good and the high hydrophilic polyester spunlaced nonwoven also has the smaller bending stiffness and much higher water absorption than ordinary polyester spunlaced nonwoven by the basic properties tests of two different polyester nonwovens. It also analyzes mechanical properties of two different polyester spunlaced nonwovens and the result shows that both longitudinal and transverse tensile strength of high hydrophilic polyester spunlaced nonwoven is much higher than that of common polyester hydroentangled nonwoven, and tangle coefficient is bigger too.(3)It remodels the fiber structure of three-dimension in the spunlaced nonwovens by X-ray tomography analysis and characterizes the 3D structure of the fibers in order to track the fiber trajectory. It can be found that snarling knot is mainly in the form of "U" type.(4)The pulling-out behavior of single fiber from hydroentangled nonwoven is first studied and used to indicate the entanglement of the fibers in the hydroentangled nonwovens. The pulling-out force can be used to weight the fiber entanglement effect in the hydroentangled nonwovens. It is found that the bigger of the pulling-out force, the more fibers are broken, the more snarling knot is contained and the resultant hydroentangled nonwovens show better tensile property. While it analyzes the stress during single fiber pull-out test and establish a mechanics model which shows that the larger friction coefficient of the fiber is, the bigger friction among the fibers is, so the pulling-out force of the fibers is bigger and the strength of snarling knot is larger.(5)It tests the cohesion of the fiber web which is carded by the carding machine carding to indirectly reflect the cohesive force among fibers and it is found that the fibers in high hydrophilic polyester fiber web have bigger cohesion force and the fibers entangled with each other much better in the spunlaced nonwoven of high hydrophilic polyester fiber which has the bigger cohesion force so the tensile strength of that nonwoven will improve, too. It is because that if fiber cohesion is big, high pressure water jet can easily carry more fibers from the fiber web surface into the fiber network to form the more tangles. At the same time, the slip force among fibers is large due to the big cohesion force so the entanglement in the web of the spunlaced nonwoven can not be easily disentangled.