Study Of Melt-spinning Process Of PVDC Resin Used For Wig

The PVDC series resin is defined as diblock copolymers polymerized by the vinylidenechloride(VDC)monomer and the second monomer such as Vinyl chloride(VC)，Methylacrylate(MA)，Acrylonitrile(AN)and so on. It is an available ideal oxygen and moisturebarrier packaging material due to the high degree of crystallinity and the dense structure,which depend on the high intermolecular forces and the symmetrical structure of PVDC blockcontained in the molecular chain. The high content of Cl in the polymer made it a flameretardant material which is beginning to be used in the Synthetic fiber and Paintareas.However, it is hard to operate and the material properties,produce equipment andtechnological parameters is strictly demanded in the process of melt spinning, as thechemically active and thermal sensitive property due to the structure of two Cl atomsconnecting to the same C atom in the VDC unit. As a result, the melt spinning processtechnique is highly monopolized by a few foreign companys. The unique high flame retardantof PVDC fiber compared with other commercially available fiber make it has a naturaladvantage and broad prospect when been used for wig. Harding to process has become thebiggest restrictive factor of the application of PVDC resin so far. As the melt spinning processis mainly determined by the factors of material properties,produce equipment andtechnological parameters, it is necessary to carry out further research of every effect factor ofPVDC melt spinning.Three-step strategy was adopted in according to the rational design of contrast tests andquantification of the experimental phenomena combined with the data analysis to study theeffect factors of spinning performance and product properties gradatim, include the process,equipment and the raw material. Step one is to determine the optimal processing parametersof the original test line, step two is to investigate the effect of different equipment on theproduct properties, and step three is to inspect the impact of the raw material on the productproperties.It turned out that the extrusion property can be improved by enlarging the spinneretdiameter, increasing the inner surface finish of the die, or magnifing the screw speed whenhunger feeding. The temperature of the fore screw should be set to low in the condition of using big hole and porous spinneret plate, flood feeding and low screw speed, otherwise theopposite. Both the relevant pressure almost linear decrease with the increase of feeding andmaintain the same value when the speed reach the saturation point, while the output increaselinearly and also remain unchangeable as soon as turning into flood feeding when hungerfeeding. However, it has little effect of the driving screw speed on the output in the abovecondition, and the output change unconspicuous over time at each different speed. The degreeof crystallization of the sample yarn from each roller was measured use the DSC method, theanalysis result show that the molten enthalpy of the sample yarn collected from the second,the third and the forth drafter’s roller almost the same, indicated that their degree ofcrystallization are similar,and the second sample yarn had reached or approached themaximum degree of crystallization. Then the draft speed curve was set according to the abovededuction,the type b curve,the result turn out to be good when adopt the type b curve. Thefinal yarn exhibit a fineness standard, larger hot shrinkage rate and poor feel performance inthe condition of type L combination temperature, flood feeding, big hole porous spinneretplate, no temperature control drafer, type C draft speed curve, water bath temperature controland dry hot oven heat treatment. Nevertheless, when drafted with hot rollers, an reverseproperty of fineness standard and good feel of the final yarn can be obtained in a condition ofhigh speed and power draft before the second drafter, maintain a velocity contrast of10~15m/min between the second and the third drafter,1m/min between the third and the forth,the fifth and the sixth drafter and5m/min more or less between the forth and the fifth drafterroller, the temperature of every hot roller remain the same value, the final diameter can reach0.07mm, the hot shrinkage rate12%and the Young modulus1.21GPa.