再生聚酯直纺涤纶工业丝成套设备技术探讨

采用回收聚酯(PET)瓶片,通过液相增黏直接纺丝生产涤纶工业丝,探讨了再生聚酯直纺涤纶工业丝的成套设备和工艺技术。结果表明:对干燥设备和螺杆挤压机进行改造,利用双级熔体预过滤器和液相增黏系统,聚酯瓶片再生增黏后特性黏数可达(0.85±0.01)dL/g;该成套设备的关键是采用单轴式液相增黏反应器;调整纺丝和拉伸工艺,直接纺丝生产的涤纶工业丝线密度为1 189 dtex,断裂强度为7.98 cN/dtex,断裂伸长率为14.66%,达到了常规固相增黏法生产的涤纶工业丝的性能指标。     

涤纶工业丝液相增黏技术的研发

通过比较卧式和立式增黏反应器对聚酯液相增黏反应的影响,自主设计研制了生产能力为29 t/d的立式液相增黏反应器;将聚酯切片螺杆加热熔融后的熔体进行增黏反应,探讨了液相增黏工艺条件,并对比分析了液相增黏与固相缩聚后纺制的涤纶工业丝的性能。结果表明:聚酯液相增黏后的熔体特性黏数达1.05 dL/g,b值小于3,端羧基浓度约25 mol/t;增黏后的熔体进行直接纺丝,生产的涤纶工业丝的各项性能指标均能达到固相缩聚熔融纺丝工艺的同等水平,断裂强度为8.33 cN/dtex,断裂伸长率为15.4%;液相增黏技术具有设备投资省、能耗和运行成本低等特点。     

废聚酯直纺涤纶工业丝成套装备和工艺开发

涤纶工业丝以往多用固相缩聚的方法制备,液相增黏均化技术使废聚酯通过预处理,螺杆,均化增黏,熔体输送,纺丝等过程直纺工业丝,很好地满足了循环经济的需求,形成了具有自主知识产权的高黏度聚酯生产装备和技术工艺。     

涤纶工业丝熔体直纺生产技术的研发

采用液相增黏聚酯熔体,开发了200 kt/a涤纶工业丝熔体直纺生产技术,探讨了高黏熔体输送和大容量多头重旦纺丝等工艺,并与固相缩聚切片纺进行了对比分析。结果表明:涤纶工业丝熔体直纺技术省去了冷却切粒、固相缩聚、熔融挤出等工序,工艺流程紧凑,提高了生产效率,比固相缩聚熔融纺丝设备投资减少44.3%,生产能耗下降32.46%;生产的各种规格的涤纶工业丝质量指标符合国家标准GB/T16604—2008。     

纳米SiO_2对PET熔体的增稠作用及改进方法

研究了分散剂种类、纳米SiO2添加量、微观结构、以及PEG的添加对PET特性黏数的影响。结果表明:纳米SiO2对聚合物熔体具有增稠作用,随着纳米SiO2含量的增加,PET的特性黏数下降;且具有多孔结构的纳米SiO2对PET熔体的增稠作用显著;分散剂的种类对合成PET/纳米SiO2复合物的分子量亦有一定影响,采用A1230时其分子质量最大;添加PEG共聚后,纳米复合材料的特性黏数可相应提高。     

再生聚酯的流变性能研究

以废旧聚酯(PET)纺织品为原料,加入不同量的乙二醇使其醇解,经液相增黏制得再生PET切片。采用毛细管流变仪对再生PET及纯PET的流变行为进行了对比研究。结果表明:再生PET流体为非牛顿假塑性流体,其流变行为与纯PET基本相同;在同一温度和剪切速率下,再生PET的熔体特性黏数小于纯PET熔体特性黏数;再生PET的黏流活化能(Eη)大于纯PET的Eη,最高达到246.1 kJ/mol;不同再生PET对温度有不同的敏感性,在纺丝加工时应采用不同工艺。     

液相增黏再生聚酯非等温结晶动力学研究

将废旧聚酯(PET)纺织品摩擦成形制成摩擦料,再经螺杆熔融挤出制得其共混摩擦料,然后采用立卧双釜串联系统对共混摩擦料进行液相增黏制得再生PET(R-PET),实现废旧PET纺织品的再生利用;利用差示扫描量热(DSC)对R-PET进行非等温结晶动力学研究,并与常规PET切片进行比较。结果表明:R-PET的特性黏数由未增黏前的0.580~0.595 d L/g增加至0.635~0.655 d L/g;DSC分析中,在同一降温速率下,R-PET的结晶峰温度高于常规PET切片,半结晶时间小于常规PET切片;利用Mo法可以较好地描述R-PET及常规PET切片的非等温结晶过程。     

微醇解-液相增黏法制备高品质再生聚酯

为了寻求低成本、高附加值的再生方法,提出了微醇解与液相增黏结合的方式回收废旧聚酯(PET)纺织品。通过工艺探索及优化,确定了最佳工艺参数为:m[Zn(OAc)2]∶m(EG)∶m(PET)=1∶2.5∶1 000,醇解温度280℃,醇解时间10 min,自由沉降反应器温度275℃、压力4.0×104Pa,圆盘成膜反应器温度280℃、压力100 Pa。制备的再生PET熔体的特性黏度为0.658 d L/g,多分散性系数为2.14。与不经微醇解直接液相增黏的工艺对比,该再生方法使过滤器使用周期延长1.8倍,螺杆的加热和电机功率降低16%,节约了大量的能耗;且能够有效解决液相增黏过程中旋风分离器管道与反应釜之间管道堵塞和蒸汽喷射泵冷凝器易结焦的问题。     

分子量分布对聚酯性能的影响

研究了不同分子量分布聚酯的热性能、结晶性能和熔体挤出性能。结果表明,随分子量分布加宽,熔体结晶峰的峰温逐步升高,过冷程度降低,蜂形由宽矮形变为高尖形,而冷结晶峰峰温逐渐降低,峰形由宽变窄。同时,随分布加宽,结晶速度加快。在等混结晶过程中,在180℃附近出现结晶速度极大值,而且此极大值与分子量分布无关。此外,随分子量分布加宽,聚酯热稳定性略为下降,在熔体挤出过程中的粘度降增大,挤出过程迅速恶化,以致于难以成形。     

高黏度聚酯流变行为的研究

采用毛细管流变仪研究了高黏度聚酯(PET)的表观黏度及黏流活化能随温度(280～300℃)及剪切速率(20～104s-1)的变化。结果表明:高黏度PET熔体随着剪切速率的增加出现切力变稀现象,随着熔体温度升高,剪切速率对熔体的表观黏度的影响降低;高黏度PET的黏流活化能随着剪切速率的提高而降低;在温度为300℃,剪切速率为3 000 s-1时,高黏度PET熔体具有较好的流动性。     

Study on the melt‐spinnability of poly(L‐lactic acid)

In this work, three kinds of different poly(L ‐lactic acid) (PLLA) materials for melt‐spinning were investigated with respect to the molecular weight (MW) and molecular weight distribution (MWD), racemization, optical purity, thermal properties, and melt‐spinnability. It was found that the high MW was not the only factor to affect the melt spinnability of PLLA, the racemization and the amount of residual monomer would also affect the thermal properties and melt‐spinnability of PLLA. The results showed that it could be melt‐spun and hot‐drawn by using the general melt‐spinning device for PLLA pellet with good stereoregularity and comparatively high MW. For PLLA pellet with high MW and moderate stereoregularity, it must be treated at an appropriate temperature to increase the crystallinity before dry and extrusion, which could make the pellet be spun without agglomeration, whereas the draw ability of such as‐spun fiber was still poor. However, if the stereoregularity of PLLA pellet was poor, it could not be spun even it had very high MW. Only when MW, racemization, and the amount of residual monomer of the PLLA pellets all meet the requirements, PLLA fibers could be prepared by melt‐spinning. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

用于制备高强Lyocell纤维的纤维素混合浆粕的研究

研究了在高聚合度的纤维素浆粕中添加少量的中等聚合度浆粕,所形成的混合浆粕的纺丝情况及得到的Lyocell纤维的性能。在此基础上,利用凝胶渗透色谱法(GPC)测定了混合浆粕的相对分子质量及其分布,分析了混合浆粕的相对分子质量及其分布对可纺性及纤维性能的影响。结果表明:这种混合浆粕的相对分子质量分布明显变宽,其中高相对分子质量的峰几乎没有变化,但中低相对分子质量部分含量增多,出现了较小的中低相对分子质量峰。这些中低相对分子质量部分的纤维素起了增塑作用,使加工更容易,而高相对分子质量部分则赋予纤维良好的力学性能。     

PET废丝再生直纺涤纶工业丝技术的开发

研究了PET工业废丝液相增粘再生工业丝的加工工艺及再生熔体的流变性能,并与传统废丝再生的能耗做了比较.结果表明：再生聚酯熔体为切力变稀流体,其流变性能与原生聚酯基本一致;与传统工艺相比,采用液相增粘技术减少了加工工序,大大降低了能耗;纺制的丝强度为7.51 cN/dtex,断裂伸长率为14.4％,干热收缩率（177℃,0.05 g/D,1 min）为7.1％,满足涤纶工业丝的性能要求.     

无油牵伸技术生产涤纶FDY的工艺探讨

采用无油丝先牵伸、热定形后再上油的新工艺路线生产83 dtex/36 f涤纶全拉伸丝(FDY),讨论了熔体特性黏度、U-guide进出距离、预网络气压、热辊温度等对纤维可纺性和染色M率的影响。结果表明:当熔体黏度和预网络气压控制在0.639 d L/g和0.020 MPa,U-guide进出距离控制在1.0~1.5 cm,热辊GRa、GRb、GRc和GRd的温度分别为65、70、128和128℃时,纤维可纺性和染色M率都较好。     

3000t/a回收聚酯布液相增黏装置工艺

介绍了3 000 t/a回收聚酯布液相增黏装置的工艺流程,包括原料的前期预处理,螺杆挤出过滤,均化增黏,熔体输送,真空和热媒系统,工艺设备及布置,投料生产以及"三废"治理。该项目作为创新性的清洁化生产工艺,具有示范作用和推广价值。     

国产Z30S聚丙烯纺制细旦丙纶复丝的研究

研究了国产Ｚ３０Ｓ聚丙烯及其改性切片的分子量（ＭＷ）和分子量分布（ＭＷＤ）以及纺丝工艺对纺制细旦丙纶复丝可纺性和卷绕丝结构性质的影响。研究表明，采用Ｚ３０Ｓ切片即使纺丝温度高达２８０℃时，卷绕丝仍是α晶型结构，若添加少量降温母粒共纺或经改性后纺丝，卷绕丝可获得准晶型或混晶型结构，有较好的可纺性和后拉伸性；纺丝工艺条件，诸如纺丝温度、冷却条件、泵供量和纺丝速度等对卷绕丝的结构和性质虽起重要的影响，但ＰＰ的ＭＷ和ＭＷＤ则起首要的影响。     

超高速BOPP薄膜专用料的研制和开发

研究了超高速双向拉伸聚丙烯薄膜(BOPP)专用料的分子结构,即分子质量和分子质量分布、熔融与结晶行为,优化了生产工艺和添加剂体系。结果表明,所研制的专用料分子质量分布宽,达7.0,并增加了超高分子质量部分,熔点和结晶度略低,分别为163.37℃、40.33%,链段规整性稍差,具有良好的抗热、氧降解能力,在450 m/m in的超高速拉伸速度下能长期连续稳定生产。     

热熔型纸塑复合预涂膜的研制

以EVA弹性体为主体材料,配以适宜的增粘树脂及其他助剂,制成热熔胶粘剂并涂于BOPP或聚酯膜上,用于纸塑复合。讨论了各种基料对热熔胶软化点、熔融粘度的影响。该预涂膜性能优良,无毒无污染,复合工艺简单,可提高生产效率。     

Flow properties of molten ethylene–vinyl acetate copolymer and melt fracture

In an investigation of the behavior and formation mechanism of melt fracture the flow properties of molten ethylene–vinyl acetate (EVA) copolymer in the region of high shear rate were measured with a capillary-type rheometer. EVA copolymer differs slightly in flow curve from low-density polyethylene (LDPE); it seems, however, that the difference is due to the difference in molecular weight distribution (MWD) rather than to the materials themselves. The fluidity of molten EVA copolymer having a narrow MWD is equivalent to that of LDPE having a broad MWD and, generally, EVA copolymer has a higher fluidity than LDPE. It is expected that the fluidity increases with incorporation of vinyl acetate at the same MWD and the same M?_w. The critical shear rate increases with melt index and temperature. It cannot be found that the materials themselves and the MWD directly influence the critical point of melt fracture formation when the melt index is taken as a parameter. The critical viscosity (η_c) at which melt fracture forms decreases in an almost straight line with an increase of melt index. It was found from the studies of end correction and behavior of melt fracture formation that melt fracture occurs at the inlet of the die, and it is supposed that the melt fracture formation is caused by the elastic turbulence in the flow pattern due to a failure of recoverable shear strain at the die inlet.     

The application of size-exclusion chromatography to study molecular-weight changes of flame-retardant fiber-reinforced polyesters

Reinforced plastics based on poly(cyclohexanedimethylene terephthalate) (PCT) are excellent for electrical and electronic applications, particularly in the manufacture of electrical connectors. PCT offers a high heat deflection temperature, low cost, and relative ease of processing. For the injection molding process, stability of the melt is an important consideration, especially for materials with high melting points such as PCT. The combination of the polyester resin with flame retardant additives, processing aids, and thermal stabilizers results in a number of competing reactions which can change the molecular weight and molecular-weight distribution (MWD) of the base polymer in the composite. Typical analytical techniques such as melt or dilute solution viscosity do not give adequate means of monitoring these changes so as to allow the polymer chemist to determine the effects of various additives on MWD. Size-exclusion chromatography (SEC), by virtue of providing information on the entire MWD, was found suitable to study molecular-weight changes in the melt due to both branching and chain cleavage, even when both phenomena occur simultaneously. Changes in the MWD over time at processing temperatures can be used to determine kinetic parameters and have been used to optimize PCT additive formulations for best processability and mechanical property retention.