Study On The Meltblown Process And Performance Of Watersoluble Polyvinyl Alcohol

Water-soluble polyvinyl alcohol(PVA) nonwovens have ideal water soluble temperature, enough tenacity and favorable properties when resist to acid, alkali and heat, its water solution is innoxious and transparent, it can decompose naturally in very short time without polluting the environment. Thus it is 100% environmentally friendly product. Because of its special water soluble property, different kinds of PVA nonwovens are developed and used in more fields.In this dissertation, a great deal of literature of home and worldwide were reviewed, the manufacturing technology and application of water-soluble PVA fiber and water-soluble PVA nonwovens were introduced, the prospect of water-soluble PVA nonwovens were predicted, and the water soluble mechandism of fiber was briefly analysed as well. The rheological behavior, melting piont and crystallinity of PVA slice were tested, which can provide evidence to determine the spinning process parameters. The investigation of this paper can provide certain basis for the development of water-soluble meltblown nonwovens in China. In this research, through analysing the properties of PVA slice, then some conclusions are as follows:(1)Because PVA is a pseudoplastic fliud which exhibits the shear thinning behavior, non-newtionian index number of PVA increase with increase of the temperature, the shear thinning behavior becomes more obvious in the range from 220-230℃, which means that the flow behavior becomes better with the increase of the temperature.(2)The melting point of PVA is 212.5℃is on the curve of Differential Scanning Calorimetry, and it started to lose weight at about 353℃on the curve of thermogravimetic.(3)In this paper was used PP to wash the extruder, when all PP was push out, the spinning temperature of the screw was cooled down to 220-240℃. By adjusting screw bolt temperature, the temperature and the pressure of hot air, the speed of rolling drum and the receiving distance, the spinning parameters were determined finally.After analysing the structure and performance of meltblown fiber web, we can get conclusions as follows:(1) relationship between the hot air temperature and the structure and performances of PVA meltblown nonwoven.PVA fibers become finer with the increase of the air temperature, the fineness of PVA fiber fall from 75μm to 45μm, and the tenacity of meltblown nonwoven is improved as well. It's tenacity in CD direction is bigger than that in MD direction. The maximum and average pore size of meltblown PVA calendered nonwovens decreased with increase of the pressure of hot air in a range. The water soluble temperature of PVA nonwovens increases with crystallinity increment, but the weight loss inthe hot water will decrese by increasing crystallinity of fiber.(2) relationship between hot air pressure and the structure and performances of PVA meltblown nonwovenPVA fibers become finer with the increase of the air pressure. The maximum and average pore size of PVA meltblown calendered nonwovens can decrease by increasing pressure of hot air in a range. The water soluble temperature of PVA nonwovens increases with crystallinity increment, but the weight loss in the hot water will decrese by increasing crystallinity of fiber.(3) relationship between transverse times and the structure and performance of PVA meltblown nonwovenThe density and tenacity of PVA nonwoven increase with the transverse times, and obviously the CD direction of the PVA nonwoven's tenacity is bigger than that in MD direction.