Disquisition Of The Structure Performances And Finishing Of The Stitch-Bonded Material

Combined with the application of stitch-bonded materials used in car-repellent layer projects in Shanghai ShenDa Nonwovens Co., Ltd, the factors and techniques which will have influence on the structure, physical and mechanical properties, and water or oil repellence of the stitch-bonded materials were studied in this thesis.Stitch-bonded fabric is a hybrid technology, using elements of nonwovens. It is used in sewing and knitting processes to produce a wide range of fabrics that are used in home furnishings and industry fabrics. It was first applied in the 1950's in Europe.The main machine for the production of stitch-bonding materials is Malivelies, which can work without the use of thread. The needles hook some fiber from the web and consolidate the strength of the fiber web by the loop which is shaped by the Malivilies. There are four steps in one cycle-take off, bend fiber, wreathe and pull. But it always need the finish treatment, such as coating, hot set, agglutinate, add the pastern, water proof and so on.The main production procedure for stitch-bonded material is: opening→blending→carding→cross extending→stitching→rolling→finishing. This is a typical procedure for nonwovens and posses the characteristic of nonwovens: brief process, occupy small area, little noise. Meanwhile, the web can be reinforced into finial product with only one step.The raw material for stitch-bonded fabric is chemical fiber like wool. The fiber fineness is 033-0.88tex with some crimps. The fiber in length direction should occupy most of the web when the fiber is feed in. By doing this, the slot needle can cross the fiber in the web and wreathe.The key points in production technique of stitch-bonded fabric procedure include the web evenness, thickness, density and the balance of machines speed. The web evenness includes the evenness of forming the web and evenness of laying the web. In order to obtain the good quality product with lower cost, the fiber in the web must be blended fully and distributed evenly. The unevenness of single fiber web can be overcome by putting webs layer by layer. The web density becomes consistent by this way. The density of stitch-bonded fabric is decided by the density and thickness of fiber weight.The structure of stitch-bonded material is different from some other non-woven materials, such as needle punching material, water jet material, thermal bonding material, melt blowing material and spunlaid material. The face presents clear loops and the end of the fiber protrude the back of stitch-bonded material; there are clearly needle marks along the landscape orientation in the back. The factors that affect the structure of stitch-bonded materials are mainly the size of needle, fiber fineness, fiber length, web density, and climbing and laying techniques. The finer of the fiber, the more detailed non-woven materials we can get. The longer of the fiber, the more stable of the fabric can be. With suitable web density, the final product can have perfect structure and visual effect with good hand.The tenacity of fiber web in the horizontal direction is bigger than in vertical direction. The fracture of stitch-bonded material is caused by the slippage of fiber. The fibers in the web cannot be damaged at the same time and there will be fluctuation of fiber intensity when the material was damaged. There are some difference with the destroy format between the horizontal direction and vertical direction. The main factors which affect the tenacity of stitch-bonded materials are the fabric kind, structure, thickness and needle:size .etc. The bursting strength of stitch-bonded material has a linear relationship with fabric density. It has only one time of stitch so the interlude of the fiber is little. The fiber can be easily pulled out when the web is subjected to friction.After several experiments the best techniques for water & oil resistance finish is: TK 285E finish liquor, finish liquor in 30 centigrade, adding JFC inhydronium surface active reagent, 30g/L thickness of finish liquor, double dip and double roll, 10 seconds dip time, baking in 180 centigrade three minutes and drying to dry. In order to get good oil resistance, the concentration of finish liquor should be improved.When stick the stitch-bonded material and melt blowing material by melt powder, the temperature should be 20℃higher than melt centigrade of the melt powder so the melt powder can melt in short time with its best glutinosity. The pressure should be set with the request of the peel off and don't damage the cloth cover. The experiment indicated that when 3155 type melt powder was used the best techniques were: 145 centigrade, 5 kg/cm~2 pressure, 5 seconds pressure time. Under this technique the peel off strength of the:stick material can get 25.20 N and little damage to the material cover.A comprehensive idea about the structure and basic performance of the stitch-bonded nonwovens can be obtained through the above research. This provides a theoretical foundation for the finishing. The factors influence the oil and water repellency and optimum technique can be found out. This research will be very helpful for the factory to develop the stitch-bonded materials used in the Automobile repellent...