不同PET切片固相缩聚主副反应规律研究(Ⅲ)

本文接近于工业生产的装置上对几种不同工艺生产的PET切片的固相缩聚进行了对比研究,指出在固相缩聚中,PET的链增长仍符合普通的二级反应动力学方程,且与文献报道一致。用直接酯化工艺生产的有光切片和半消光切片进行固相缩聚时,其动力学行为相似;用酯交换工艺生产的PET切片进行固相缩聚时,难以得到高分子量的产物;直接酯化中不同TPA/EG配比所得到的PET切片的固相缩聚动力学行为相似。实验还发现,在PET切片的固相缩聚中,羧端基含量有所下降,醚键含量基本不变。这些结果对于为满足不同用途而选择固相缩聚所用的PET切片具有重要意义。     

PET固相缩聚工艺技术分析

综述了聚酯(PET)固相缩聚过程特点,重点对比分析了Bepex、Buhler、Sinco及Dupont的NG3连续固相缩聚工艺、关键设备构型及主要操作参数。PET固相缩聚过程中结晶增长与缩聚反应共存并互相耦合,因而结晶工序是固相缩聚工艺的重要组成部分,也是各工艺专利商的专利技术之所在。有效的结晶增长、结晶形态与缩聚反应的解耦合是强化固相缩聚技术的科学基础。     

聚对苯二甲酸乙二酯(PET)固相缩聚动力学研究

本文以小型真空转鼓为反应装置,研究了PET的固相缩聚动力学,采用的PET预聚体是直接酯化工艺生产的未消光切片和酯交换工艺生产的不同厚度的薄膜。实验结果指出:在本实验条件下,PET预聚体的链增长速度在215℃处有一转折。动力学数据处理的结果表明:在固相缩聚期间PET的链增长按二级反应进行,而且与文献报道的动力学结果基本一致。对不同厚度的薄膜进行固相缩聚动力学研究,并用拉格朗日插值法外推到厚度为零,得到了消除样品层厚度影响的化学反应的表观动力学。实验结果还发现,左PET预聚体的固相缩聚期间,羧端基含量有所降低,醚键含量基本不变,并从反应机理上给予了说明。     

FDY高强聚酯长丝生产技术研究

较系统地研究了 PET 切片的固相缩聚工艺、高粘度切片的熔融纺丝以及拉伸卷绕工艺.研究结果表明:采用国内 TPA 法生产的 PET 大有光切片,选择合理的固相缩聚工艺,可满足高强聚酯长丝的生产需要;在切片固相缩聚过程中,对粘度增长贡献的大小依次为:真空度>温度>时间;无油丝粘度在0.92dL/g 左右,聚酯纤维可获得优良的物理机械性能和良好的热稳定性.     

固相缩聚扩链PET的结晶与流变性能研究

利用固相缩聚法在不同缩聚时间制备扩链聚对苯二甲酸乙二醇酯(PET),对扩链PET的流变性能及结晶行为进行了研究。结果表明:PET粉末经过8 h的固相缩聚,特性黏度最佳为1.30 dL/g,此时扩链PET的流动性明显降低,熔体流动速率(MFR)由纯PET的81.3 g/10 min降至34.9 g/10 min。流变性能也有一定程度的变化,随着固相缩聚时间的延长,扩链PET复数黏度呈现依次升高的趋势,并且与改性前的PET相比,剪切变稀现象更明显。同时,固相缩聚后PET的结晶能力变差,产物在降温过程中甚至难以形成明显的结晶峰,结晶度从30.7%降至3.6%。     

CDP固相缩聚的研究

对N_2保护下CDP的固相缩聚进行了基础研究,得出了CDP固相缩聚的一般规律,并对实验结果进行了讨论,与常规PET固相缩聚的一些规律进行了比较,同时还比较了不同反应氛围下CDP的分子量变化情况.     

PET固相缩聚反应动力学研究

建立了综合考虑 PET固相缩聚化学反应、小分子副产物物理扩散、大分子结晶三方面的 PET固相缩聚动力学模型 ,并用文献报道的实验测定数据验证该模型。运用该模型 ,研究了水、乙二醇、乙醛小分子副产物的含量与分布及其对固相缩聚的影响 ,从乙醛含量分布图可以得出 ,随着反应时间的延长 ,切片内各层乙醛含量降低不明显     

卡尔费休固相缩聚装置与工艺的改造

针对K·F连续同相缩聚生产装置存在的结晶不均、结晶度不够,粘料及乙醛含量高等问题,对原装置和工艺进行了技术改造.改造后,各项技术指标达到了预期目标,PET的连续固相缩聚技术和产品质量在国内处于领先地位。     

十四烷辅助下聚酯的固相缩聚

在200～240℃研究了聚对苯二甲酸乙二醇酯(PET)在十四烷辅助下的固相缩聚反应.结果表明,溶剂辅助下的固相缩聚(分散相固相缩聚)的反应速度较传统气相环境中的固相缩聚更快,最佳反应温度为230℃左右.随着反应温度的升高,分散相固相缩聚得到的PET切片的熔点和结晶度也相应提高.分散相固相缩聚前后PET切片的孔隙率并未发生明显变化.用苯酚处理之后的PET孔隙率增加,有利于小分子扩散,使缩聚反应速率加快.聚合物在十四烷中溶胀导致链活动性增强可能是分散相固相缩聚分子量提高的主要原因.     

非结晶态PET片材切片色相的影响因素

论述了原料、添加剂、聚合生产工艺及固相缩聚工艺对APET片材用PET切片色相的影响,对生产配方及工艺提出建议。     

PET固相缩聚生产技术的新进展

介绍了传统的PET SSP生产技术,包括间歇法和连续法SSP的生产工艺,对不同垂直式连续SSP进行了比较。对杜邦NG3的缩聚SSP生产技术的生产流程、工艺和应用情况进行了说明。重点介绍了M&G公司的SSP最新技术——Easy UP,窑式SSP。介绍了该技术的工艺流程、工艺原理和特点,与其他反应器比较的优势。指出Easy UP PET SSP生产技术是PET固相增黏技术的新进展。     

Solid-state polycondensation of poly(ethylene terephthalate): Kinetics and mechanism

A numerical method to seek a solution for the solid-state polycondensation (SSP) proces has been proposed to analyze the mechanism of SSP. Results expound that, for the industrial SSP process of PET, the overall reaction rate in a single pellet is appropriately simulated by the diffusion and reaction rate jointly controlling the model. From the core to the surface the SSP rate increase monotonically due to a gradual reduction of the concentration of such by-products as ethylene glycol and water. However, the SSP rate at any location within the pellet is constrained between two purely reaction rate controlling cases. © 1995 John Wiley & Sons, Inc.     

PET瓶级切片品质控制

从共聚有光切片和固相缩聚生产工艺条件2个方面分析了影响PET瓶级切片性能的因素。通过优化工艺参数和调整共聚有光切片的配方来满足市场要求,为提高瓶级切片的品质作进一步的探讨。     

Microstructure and properties of poly(ethylene terephthalate)/organoclay nanocomposites prepared by water‐assisted extrusion: Effect of organoclay concentration

Poly(ethylene terephthalate) (PET)/Cloisite 30B (C30B) nanocomposites containing different concentrations of the organoclay were prepared using two different twin‐screw extrusion processes: conventional melt mixing and water‐assisted melt mixing. The reduction of the molecular weight of the PET matrix, caused by hydrolysis during the water‐assisted extrusion, was compensated by subsequent solid‐state polymerization (SSP). X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy analyses showed intercalated/exfoliated morphology in all PET/C30B nanocomposites, with a higher degree of intercalation and delamination for the water‐assisted process. Rheological, thermal, mechanical, and gas barrier properties of the PET nanocomposites were also studied. Enhanced mechanical and barrier properties were obtained in PET‐C30B nanocomposites compared to the neat PET. The nanocomposites exhibited higher tensile modulus and lower oxygen permeability after SSP. The elongation at break was significantly higher for SSP nanocomposites than for nanocomposites processed by conventional melt mixing. POLYM. ENG. SCI., 54:1879–1892, 2014. © 2013 Society of Plastics Engineers     

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。     

Solid state polymerization (SSP) of low molecular weight poly(ethylene terephthalate) (PET) copolyesters compared to conventional SSP of PET

SSP, starting from very low molecular weight (MW) poly(ethylene terephthalate) (PET) precursors, is claimed to offer significant production cost advantages over conventional PET production. However, as the intrinsic viscosity (IV) of the PET precursor is reduced, there is a significant change in the crystallization behavior of PET and morphology that affects reactivity in SSP. Using small particle size PET to significantly reduce the effects of diffusion so that SSP is under chemical reaction control and using a kinetic model that describes an overall SSP rate, the effect of ethylene isophthalate substitution on the SSP rate from low MW PET precursor was determined. As the ethylene isophthalate comonomer content increases, the rate of SSP for low MW PET increases. The activation energy for SSP of low MW PET decreases with an increase in the ethylene isophthalate content. For the low MW PET copolyesters in this study, the SSP activation energy is comparable to conventional process when the comonomer content of the low MW polyester is around 7 mol % and the conventional precursor is around 3 mol %. However, even though the activation energy is reduced through the use of higher comonomer content, the overall rate of SSP for the low MW copolyesters studied is significantly slower than conventional SSP. This reduction in rate is explained by differences in crystallinity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 230–238, 2002     

Solid‐state polymerization of poly(ethylene terephthalate): Effect of organoclay concentration

Poly(ethylene terephthalate) (PET)/Cloisite 30B (C30B) nanocomposites of different organoclay concentrations were prepared using a water‐assisted extrusion process. The reduction of the molecular weight (M_w) of the PET matrix, caused by hydrolysis during water‐assisted extrusion, was compensated by subsequent solid‐state polymerization (SSP). Viscometry, titration, rheological, and dynamic scanning calorimetry measurements were used to analyze the samples from SSP. The weight‐average molecular weight (M_w) of PET increased significantly through SSP. PET nanocomposites exhibited solid‐like rheological behavior, and the complex viscosity at high frequencies was scaled with the M_w of PET. The Maron–Pierce model was used to evaluate the M_w of PET in the nanocomposites before and after SSP. It was found that the extent and the rate of the SSP reaction in nanocomposites were lower than those for the neat PETs, due to the barrier effect of clay platelets. Consequently, the SSP rate of PET increased with decreasing particle size for the neat PET and PET nanocomposites. The effect of the M_w of PET on the crystallization temperature, crystallinity, and the half‐time, t_½, of nonisothermal crystallization was also investigated. With increasing M_w of PET, t_½ increased, whereas T_c and X_c decreased. POLYM. ENG. SCI., 54:2925–2937, 2014. © 2014 Society of Plastics Engineers     

瓶级聚酯的生产技术和应用

叙述了瓶级聚酯生产概况 ,介绍了以固相缩聚 (SSP)法生产瓶级聚酯过程及其优化技术 ;此外 ,还介绍了它的应用 :如用于矿泉水、碳酸软饮料 (CSD)、热灌装饮料、啤酒等的灌装     

PET固相缩聚生产过程优化

对PET(聚对苯二甲酸乙二酯)连续固相缩聚生产过程进行探讨,对生产过程中的并颗和结晶度变化进行分析,讨论原料切片、反应温度、升温速率、反应时间和循环氮气流量及纯度对固相缩聚反应的影响,用于指导生产,调整优化工艺,提高产品质量。     

PET recycling: Evaluation of the solid state polymerization process

Many studies have been carried out to make bottle‐to‐bottle recycling feasible. One of the difficulties found is the decrease in the polymer's molar mass, which damages the injection blow molding process. A method usually employed to increase the molar mass of virgin PET consists of solid‐state polymerization (SSP). In this work, we studied the SSP process applied to post‐consumer recycled PET by analyzing the inherent viscosity and amount of carboxylic end groups, and the results of dynamic flow rheometry. Although the results show that the recycling process decreases polymer molar mass, and this indicates degradative processes, SSP was successful in increasing molar mass in post‐consumer recycled PET. This made feasible bottle‐to‐bottle recycling. In addition, the parallel plate rheometry technique was powerful in assessing the degradative process and, therefore, that the SSP process was successful. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006