涤纶POY纺丝工艺的计算机模拟研究

基于熔融纺丝动力学模型及理论,在已知物性参数的情况下,计算模拟了不同线密度、纺丝速度、吹风速度对涤纶预取向丝(POY)丝条温度、速度、应力、直径在纺程上的变化.结果表明:随着线密度、纺丝速度、吹风速度的增加,涤纶POY丝条温度、速度、应力沿纺程递增;纤维直径随线密度的增加而增加,纺丝速度、吹风速度对纤维直径的影响很小.     

干法纺丝制备聚碳硅烷纤维中残留溶剂含量的影响因素

研究了聚碳硅烷纤维纺丝线上残留溶剂含量的影响因素.结果表明:在纺丝线上距离喷丝孔约0.3 m之内,溶剂的挥发主要由对流和闪蒸过程控制,残留溶剂含量呈指数速率减小,且溶剂挥发量约为纺丝线上溶剂挥发总质量的80%～90%;纺丝原液浓度的增大、纺丝甬道温度的升高和纺程的增加有利于残留溶剂含量的降低,而纤维直径的增大则会提高残留溶剂含量.较佳的纺丝条件为:纺丝原液中聚碳硅烷的质量分数为65%～68%,纺程0.3～1.5 m,纺丝甬道温度为室温.     

花色纺丝II.冷管热管纺丝张力不匀及工艺调节

冷管与热管上纺丝因不同的纺丝温度导致纤维的张力不同 ,丝条集束后在卷绕时引起卷绕成型不良。为解决由于采用新工艺所产生的卷绕张力不匀 ,在不同的纺丝工艺下 ,利用计算机对纺丝成形张力进行了数学模拟计算。计算结果显示 ,改变冷管的直径和起始位置 ,对卷绕张力无调节作用 ,且不影响纤维的结晶和取向 ,而改变热管直径 ,对卷绕张力也无调节作用 ,但使快速结晶时的位置沿纺程后移。因此 ,需要在集束点之前加装一个张力调节补偿装置 ,或者使用变径热管纺丝系统装置来调节纺丝张力     

花色纺丝Ⅱ.冷管热管纺丝张力不匀及工艺调节

冷管与热管上纺丝因不同的纺丝温度导致纤维的张力不同,丝条集束后在卷绕时引起卷绕成型不良.为解决由于采用新工艺所产生的卷绕张力不匀,在不同的纺丝工艺下,利用计算机对纺丝成形张力进行了数学模拟计算.计算结果显示,改变冷管的直径和起始位置,对卷绕张力无调节作用,且不影响纤维的结晶和取向,而改变热管直径,对卷绕张力也无调节作用,但使快速结晶时的位置沿纺程后移.因此,需要在集束点之前加装一个张力调节补偿装置,或者使用变径热管纺丝系统装置来调节纺丝张力.     

聚丙烯高速纺时筒管上的后收缩

聚丙烯高速纺丝工业化的技术难关是聚丙烯纤维在筒管上的后收缩。本工作在有导丝盘系统高速纺丝机上对后收缩过程进行研究,摸清了后收缩机理及各纺丝工艺对后收缩的影响。后收缩的产生,是熔体细流在固化过程中产生的高弹形变所致。减少或消除后收缩的原则是选择正确的纺丝温度和冷却条件以控制纺程上丝条高弹形变的产生。在一定的张力条件下,需尽可能地提供丝条的松弛时间。导丝盘的超喂是一种有效的松弛办法。     

花色纺线 Ⅱ．冷管热管纺丝张力不匀及工艺调节

冷管与热管上纺丝因不同的纺丝温度导致纤维的张力不同，丝条集束后在卷绕时引起卷绕成型不奶。为解决由于采用新工艺所产生的卷绕张力不匀，在不同的纺丝工艺下，利用计算机对纺丝成形张力进行了数学模拟计算。计算结果显示，改变冷管的直径和起始位置，对卷绕张力无调节作用，且不影响纤维的结晶和取向，而改变热管直径，对卷绕张力也无调节作用，但使快速结晶时的位置沿纺程后移。因此，需要在集整束点之间加装一个张力调节补偿装置，或者使用变径热管纺丝系统装置来调节纺丝张力。     

涤纶细旦丝纺丝理论及实践

本文根据纺丝运动学及动力学计算了涤纶不同纤度纤维的纺丝固化长度L_K及冷却速率dT/dX,定量地讨论了喷丝孔径d.对纺丝拉伸比S及剪切速率γ_w的影响,定性地分析了单丝纤度dpf对纺程上的摩擦力、流变力的影响,从而得出了细旦丝纺丝的特征.     

传热系数对中空纤维周向和径向温度梯度分布的影响

由侧吹风引起的传热系数 (h)对纤维的传热影响较大 ,尤其是不对称冷却吹风将引起纤维截面温度分布的不对称性。文中利用计算机纺丝模拟 ,详细讨论了中空纤维在强吹风条件下 ,h随纺程在截面上的变化及其对温度截面梯度的影响。对强吹风中空纤维的纺丝模拟的传热系数进行了修正     

TCS工艺对PET FDY纤维成形的影响

采用热管纺丝 ( TCS)技术 ,生产 5 5 dtex/2 4f,78dtex/36 f PET-F DY长丝。探讨了纺丝工艺对纤维成形及产品力学性能的影响。结果表明 :张力对纤维结晶取向影响不大 ,热管温度对纤维取向、结晶及力学性能均有影响 ,结晶随热管温度的升高进一步完善 ,冷却吹风温度、湿度 ,集束位置均影响纤维成形 ,一般选择冷却风温度 2 2± 1℃ ,相对湿度 6 0 %～ 80 %。集束位置根据热管长度、丝条长度等进行选择     

β晶相聚丙烯纺丝工艺的研究

本文研究了三种不同β晶成核剂的聚丙烯切片的纺丝工艺条件与初生纤维中结晶结构的关系。研究表明,制得的初生纤维中的β晶含量主要取决于含β成核剂聚丙烯的结晶速率和纺丝成形中的冷却速率。含β成核剂E3B聚丙烯的结晶速率最大,纺制的初生纤维β晶含量最高;纺丝成形中的冷却速率愈高,初生纤维中的β晶含量愈低;在一定的温度范围内,纺丝温度对初生纤维中β晶相对含量影响甚微;纺丝冷却条件和纤维束的集束状况对β晶含量有明显的影响;β晶的晶粒尺寸与β晶含量相对应,而初生纤维中的结晶度多在55％左右,受纺丝工艺参数的影响甚小。     

影响干法氨纶中残留溶剂含量的因素

考察了甬道温度、原液质量分数、纺丝速度、单丝纤度、喷丝孔形状等对氨纶丝残留溶剂含量的影响。结果表明:在甬道长度恒定的情况下,甬道温度的增加、纺丝速度的降低以及单丝纤度的减少都有利于降低氨纶丝中残留溶剂的含量;原液质量分数对残留溶剂含量的影响则比较复杂,原液质量分数35%时,残留溶剂含量随原液质量分数的升高而降低,而原液质量分数35%时,残留溶剂的含量随浓度的升高而升高;另外,选择合适形状的喷丝板也有利于降低残留溶剂的含量。     

DRYING BEHAVIOR OF ACETATE FILAMENT IN DRY SPINNING

Drying behavior of acetate filament in dry spinning is investigated, including the elongational deformation of polymer solution thread in the early stage of drying. Variations of diameter, velocity, temperature, solvent concentration profile in the thread and tension distribution along the threadline in the spinning column, are calculated for spinning conditions encountered commercially by means of the equations of simultaneous momentum, heat and mass transfer between the thread and hot air flow in the spinning column. Concentration and temperature dependencies of the mutual diffusion coefficient from desorption experiment are correlated by the free volume theory. The elongational viscosity is estimated from the shear viscosity data using Krevelen theory. Residual acetone concentratio in the thread and tension at the exit of the spinning column are compared between the calculated results and the experimental data by a commercial apparatus; satisfactory agreement is found. Rapid decreases of temperature and surface concentration of the dope thread after extrusion confine the elongational deformation within several centimeters below the spinnerette. Initial elongational rate and die swell ratio are related to the winding velocity and tension at the exit of the spinning column. The tension is determined mainly by initial viscous force and air drag.     

DRYING BEHAVIOR OF ACETATE FILAMENT IN DRY SPINNING

Drying behavior of acetate filament in dry spinning is investigated, including the elongational deformation of polymer solution thread in the early stage of drying. Variations of diameter, velocity, temperature, solvent concentration profile in the thread and tension distribution along the threadline in the spinning column, are calculated for spinning conditions encountered commercially by means of the equations of simultaneous momentum, heat and mass transfer between the thread and hot air flow in the spinning column. Concentration and temperature dependencies of the mutual diffusion coefficient from desorption experiment are correlated by the free volume theory. The elongational viscosity is estimated from the shear viscosity data using Krevelen theory. Residual acetone concentratio in the thread and tension at the exit of the spinning column are compared between the calculated results and the experimental data by a commercial apparatus; satisfactory agreement is found. Rapid decreases of temperature and surface concentration of the dope thread after extrusion confine the elongational deformation within several centimeters below the spinnerette. Initial elongational rate and die swell ratio are related to the winding velocity and tension at the exit of the spinning column. The tension is determined mainly by initial viscous force and air drag.     

DRY SPINNING OF FILAMENT

ABSTRACT

Drying and extensional behaviours of a threadline in dry spinning were investigated for polyvinylalcohol-water system. Diffusion equation, differential heat balance equation and momentum equation for extensional deformation were solved simultaneously by numerical calculation. Concentration and temperature dependencies of mutual diffusion coefficient, Trouton viscosity and vapour pressure at threadline surface, were taken into account, Rapid decrease of temperature and surface concentration of a threadline just below a spinneret cause rapid increase of the viscosity inside a threadline and limits the extensional deformationwithin a short distance.Contributions of initial viscous stress, inertia, air drag, gravity and surface tension to spinning tension were discussed. Diffusion of solvent in a threadline is controlling step of the drying rate of a threadline except the short distance below a spinneret. Changes of average concentration and temperature of a threadline in a spinning column are well correlated by a term of (distance from spinneret) / (mass velocity of polymer).     

52.5dtex/36f锦纶6POY试纺工艺

介绍了在进口锦纶高速纺生产线上试纺锦纶６多孔细旦ＰＯＹ的生产工艺,试生产证明调整和稳定切片质量,提高纺丝温度,适当缩短喷丝板与上油嘴之间的距离,采用合适的组件装配方式,降低侧吹风速度,提高纺丝上油量等是生产锦纶６细旦丝的工艺技术关键。     

PET吸管冷却熔融纺丝动力学及计算机模拟

对ＰＥＴ吸管冷却纺丝侧吸风速度（Ｖｙ＊）及吸管内空气温度（Ｔ＊）沿纺程的分布进行了理论分析,并得到纺程上丝条的应力、速度、温度以及吸管内空气温度沿纺程分布的偏微分方程组,由此计算吸管冷却条件下的纺丝动力学量。由计算机模拟结果表明,Ｖｙ＊最大处刚好就是丝条形变速度最大处,也就是丝条开始凝固处或最需冷却处。吸管内丝条的环境温度是一个分布。在靠近喷丝板的区域,Ｔ＊较高,即相当于吸进热风。随着与喷丝板距离的加大,Ｔ＊迅速下降并趋近于室温,即相当于吸进冷风。     

微细旦PA6 HOY的开发

介绍了在常规PA6 HOY生产设备上直接纺制微细旦PA6 HOY的生产工艺,分析了纺丝工艺条件、喷丝板设计、卷绕工艺等的影响。结果表明,当纺丝温度262～264℃,喷丝孔长径比2．5∶1,侧吹风温度18℃,油剂质量分数为8%,卷绕速度4 500 m/min时,可生产出单丝线密度约1．0 dtex的微细旦PA6 HOY。     

Studies on high‐speed melt spinning of noncircular cross‐section fibers. III. Modeling of melt spinning process incorporating change in cross‐sectional shape

A numerical analysis program for high‐speed melt spinning of flat and hollow fibers was developed. Change in cross‐sectional shape along the spin line was incorporated adopting a formulation in which energy reduction caused by the reduction of surface area was assumed to be equal to the energy dissipation by viscous flow in the plane perpendicular to the fiber axis. In the case of flat fiber spinning, the development of temperature distribution in the cross section was considered. It was found that the empirical equations for air friction and cooling of the spin line of circular fibers can be applied for the flat fiber spin line if the geometrical mean of long‐axis and short‐axis lengths was adopted, instead of fiber diameter, as the characteristic length for Reynolds number and Nusselt number. Three features expected through the high‐speed spinning of noncircular cross‐section fibers could be reproduced: (1) although cooling of the flat fiber spin line was enhanced, calculated tension at the position of solidification was not affected much by the difference in cross‐sectional shape; (2) change in cross‐sectional shape proceeded steeply near the spinneret; and (3) temperature at the edge became significantly lower than that at the center in the cross section of flat fibers. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1589–1600, 2001     

DRY SPINNING OF FILAMENT

Drying and extensional behaviours of a threadline in dry spinning were investigated for polyvinylalcohol-water system. Diffusion equation, differential heat balance equation and momentum equation for extensional deformation were solved simultaneously by numerical calculation. Concentration and temperature dependencies of mutual diffusion coefficient, Trouton viscosity and vapour pressure at threadline surface, were taken into account, Rapid decrease of temperature and surface concentration of a threadline just below a spinneret cause rapid increase of the viscosity inside a threadline and limits the extensional deformationwithin a short distance.Contributions of initial viscous stress, inertia, air drag, gravity and surface tension to spinning tension were discussed. Diffusion of solvent in a threadline is controlling step of the drying rate of a threadline except the short distance below a spinneret. Changes of average concentration and temperature of a threadline in a spinning column are well correlated by a term of (distance from spinneret) / (mass velocity of polymer).     

120 dtex/144 f涤纶直纺预取向丝生产工艺探讨

通过对熔体质量和工艺条件的选择,采用喷丝板孔径0.13mm,纺丝温度296℃,侧吹风风速0.35m/s,集束点位置600～700mm,纺丝速度2750m/min,以及适当控制其它工艺条件,纺得涤纶POY微细旦丝的断裂强度2.48cN/dtex,断裂伸长率127.6%,可满足后加工要求。