我国茂金属催化剂及其聚烯烃研究开发过程

本文在简述茂金属催化剂特性和预测国内外茂金属聚烯生产能力,需求的基础上,报道了我国近年来茂金属催化剂及其聚烯烃的开发进程,包括藏金属催化剂的开发,茂金属催化烯烃聚合的研究以及茂金属基烯烃树脂的结构表征及品牌开发。     

聚烯烃催化剂的发展及我们的对策

评述了聚烯烃催化剂的几个重要发展阶段，讨论了Ziegler-Natta催化剂，茂金属催化剂及非茂有机金属催化剂的组成及特征，提出了我国在聚烯烃催化剂开发方面的对策。     

后过渡金属烯烃聚合催化剂研究进展

烯烃在催化剂的作用下形成聚合物 .改变催化剂的结构 ,可以得到特定分子结构和特定性能的聚烯烃产物 ,因而催化剂的研究开发是聚烯烃升级换代的核心 .烯烃聚合催化剂的发展大致经历了 3个阶段 :Ziegler- Natta催化剂 -茂金属催化剂 -后过渡金属催化剂 .Ziegler[1]和 Natta[2 ]发现了用于各种 α-烯烃聚合的催化剂 ,并已作为主导技术应用于工业化大生产 . 2 0世纪 80年代初 ,Kaminsky等 [3～ 5] 发现 ,二氯二茂锆与烷基铝氧烷组成的体系(茂金属催化剂 )是一种高催化活性、高立体选择性、长寿命的催化剂 .茂金属催化剂的设计、合成和应用 ,…     

负载型茂金属烯烃聚合催化剂有机载体研究进展

综述了近年来各种有机载体负载茂金属催化剂的负载方法,介绍了有机载体型茂金属催化剂的特点、负载方式、负载化对催化烯烃聚合性能和聚合物性能的影响。目前还不能完全解释清楚有机载体对聚烯烃形态以及聚合活性的影响效果。在有机载体合成方面,可以通过高分子工程,进行有机载体的设计,将茂金属催化剂负载到有机载体上,进一步提高有机载体型茂金属催化剂的活性、改善有机载体的形态和结构,将会推进有机载体负载型茂金属催化剂的工业化开发。     

茂金属聚合催化剂的研究现状

198 0年德国汉堡大学的化学家 Sinn等[1] 发现了烯烃聚合用的茂金属催化剂 .茂金属催化剂为两个环戊二烯中间夹有过渡金属如 Zr、Hf、Ti等的具有三明治结构的有机金属化合物 .茂金属催化剂与传统的多相 Ziegler- Natta催化剂相比 ,具有可溶且聚合活性物种单一 ,对乙烯等烯烃的聚合活性高 ,高分子产物的分子量及组成分布窄等特点 .选择不同的茂金属催化剂 ,可获得所需立构规整性的高分子物 ,除能获得全同立构的聚烯烃外 ,还可获得由 Ziegler- Natta催化剂不能合成的间规立构聚烯烃 ,如聚苯乙烯 [2 ]与聚丙烯 [3 ] .由 Ziegler- Natta催化…     

聚烯烃催化剂及聚合物新产品研发进展

综述了已广泛应用于聚烯烃行业中聚乙烯和聚丙烯聚合用催化剂的研究进展,重点介绍了齐格勒-纳塔催化剂、茂金属催化剂、铬系催化剂、后过渡金属催化剂、复合型催化剂等催化剂研究方法及应用领域。全面阐述了齐格勒-纳塔催化剂研究趋势,总结了国内聚烯烃催化剂研究现状及应用情况。同时还论述了不同类型聚乙烯和聚丙烯新产品的聚合工艺及研究现状,重点说明了新产品的结构性能及其应用领域。最后展望了聚烯烃领域的某些可能发展方向。     

烯烃聚合催化剂和聚合反应

简要叙述了传统齐格勒－－纳塔催化剂的发展和演变,介绍了茂金属催化睡聚烯烃工业的新发展,并对新一代后过渡金属烯烃聚合催化剂的研究进展作了综合评述。     

国外聚乙烯催化工艺研究进展

聚乙烯(PE)以其性优、价廉的优势,成为通用合成树脂中产量最大的品种,主要包括低密度聚乙烯(LDPE)、线性低密度聚乙烯(LLDPE)、高密度聚乙烯(HDPE)、中密度聚乙烯(MDPE)、以及一些具有特殊性能的专用料树脂。催化剂是聚烯烃工业的核心,通过调控活性中心和改善聚合工艺,提高了催化剂活性,完善了所得聚烯烃的性能,推动了聚乙烯工业的蓬勃发展。研发特殊性能或优异性能聚烯烃树脂的催化剂,是目前聚烯烃领域关注的焦点。本文对近年来国外聚乙烯催化剂的研究进展进行了综述,重点阐述了目前研究开发中的催化工艺,涵盖了Ziegler-Natta催化剂、铬催化剂、茂金属催化剂、过渡金属催化剂以及制备双峰或宽峰分布聚烯烃的复合催化剂等;对各类新型催化剂的制备方法和工艺特点进行了总结,同时指明了相关工艺的研发公司,以便国内相关研究部门借鉴。     

4-甲基-1-戊烯与烯烃共聚用催化剂的研究进展

4-甲基-1-戊烯(4M1P)是烯烃工业中一种重要的支链α-烯烃,它的主要用途是用于制备均聚物和共聚物。虽然绝大部分4M1P共聚物尚未进入工业化生产阶段,但由于共聚物作为一类新型的合成树脂具有突出的力学性能和光学性能,已成为国外聚烯烃领域的一个研究热点。本文阐述了4M1P与烯烃共聚反应催化剂包括Ziegler-Natta催化剂、茂金属催化剂及后过渡金属催化剂的开发研究现状;重点阐述了催化剂的结构对共聚物分子结构的影响;同时也简要介绍了二亚胺镍催化剂催化4M1P共聚反应作用机理,展望了这一领域的发展趋势。为开发高端聚烯烃新材料提供参考。     

烯烃配位聚合二十年

聚烯烃树脂是消费量最大的合成树脂种类,性能优异,用途广泛。二十多年来,烯烃配位聚合技术取得了突飞猛进的发展,在催化剂、聚合方法、聚合工艺方面都有重大突破。本文综述了二十多年来烯烃配位聚合的研究发展情况,包括Ziegler-Natta催化剂,茂金属催化剂,非茂金属催化剂,配位聚合机理,功能化聚烯烃的制备,原位共聚制备LLDPE,原位聚合制备纳米复合材料,活性配位聚合以及Spherizone工艺等方面的成就。     

On the way to biodegradable poly(hydroxy butyrate) from propylene oxide and carbon monoxide via β-butyrolactone: Multisite catalysis with newly designed chiral indole-imino chromium(III) complexes

Enantioenriched poly(hydroxy butyrate) (PHB) is a biodegradable polyester of significant commercial interest as an environmentally benign substitute of commodity polyolefines. We report on the design and development of new chiral indole-based ligand families and on their chromium(III) complexes as enantioselective catalysts for the conversion of propylene oxide and carbon monoxide to enantioenriched β-butyrolactone, the key monomer for the production of PHB by ring-opening polymerization. The enantioselective carbonylation catalysts are based on new chiral tri- and tetradentate [N₂O] and [N₄] chromium(III) complexes containing chiral indolaldimine ligand scaffolds. The conceptual design of these ligands is inspired by Jacobsen’s salicylaldimine lead structure; the key difference is an exchange of the salicyl-O-donor against an indole-N-donor, allowing additional structural diversity and stereoelectronic tuning by the indole substitution pattern. Synthetically, chiral indolealdimines are easily accessible from 7-formylindoles by standard Schiff base condensation with chiral amine building blocks; the 7-formylindoles in turn are synthesized from the corresponding 7-bromoindoles by the Rapoport synthesis, and the starting 7-bromoindoles are accessible from 2-bromoaniline by the classical Fischer indole synthesis. Three generations of chiral [N₂O] and [N₄] chromium(III) catalysts have been developed and evaluated in the enantioselective carbonylation of racemic propylene oxide with carbon monoxide using tetracarbonylcobaltate as the nucleophilic reagent for the insertion of carbon monoxide into the activated propylene oxide/chiral Lewis acid complex. The best catalyst out of 10 candidates showed at a temperature of 80 °C an activity of 37% conversion, 100% chemoselectivity, and 19% stereoselectivity.     

Post-irradiation grafting of tetrafluoroethylene at low temperatures

Low-temperature postirradiation grafting of tetrafluoroethylene (TFE) to polyolefines and silicone elastomers was the subject of study. After preliminary dissolution of TFE in the polymer at 273°K the system was slowly cooled to 77°K. In this process a certain part of TFE in polyolefines (ethylene-propylene copolymer and polypropylene) is retained by the vitreous polymer matrix. When slowly heated after radiolysis at 77°K this system shows graft polymerization of dissolved TFE after T_g. The graft copolymer is soluble and its IR spectra contain absorption bands characteristic of polytetrafluoroethylene. In polydimethylsiloxane rubber (SKT) the dissolved TFE when frozen to 77°K remains sorbed between the SKT crystallites rather than in a separate phase. When these radiolyzed samples are heated the graft-polymerization occurs primarily over the temperature range between the TFE and SKT melting points. The technique provedes for 100–150% grafting of TFE. This method also permits grafting to silicone rubbers and to several other polymers and elastomers.     

Quelques caracteristiques morphologiques de melanges de polymeres a base de propene et de butene

This paper reports a study of the morphology of blends of polypropene with polybutene as a function of composition. Techniques such as differential thermal analysis, thermomechanical analysis and dilatometry were used. The “compatibility” of these polyolefines is considered. Glass transition temperatures of the homopolymers are detectable when using the various techniques.     

A permanganic etchant for polyolefines

A permanganic etchant has been developed which reveals lamellar and other fine detail in surfaces of at least three crystalline polyolefines, viz., polyethylene (of both high and low density), isotactic polypropylene, and isotactic poly(4-methylpentene-1). In typical treatments of high-density polyethylene ca. 2 μm of material is removed with defective regions suffering preferential attack. The etchant also discriminates between lamellar orientations, eating deeper where side surfaces of laminae are exposed than on fold surfaces, and between different polymers, attacking isotactic polypropylene more strongly than polyethylene. Comparison with other techniques authenticates the detail exposed and samples appear to be otherwise unaltered by their treatment. Besides normal imaging, it is also possible to use etched samples for transmission diffraction studies in the electron microscope. The method has very considerable application for revealing lamellar details in crystalline polyolefines (which can be chosen to be representative or selective according to the nature of the surface used). Examples are given of a wide variety of melt-crystallized morphologies for the three polymers cited and also of lamellae in a drawn polyethylene sample. It is pointed out that permanganic etching is complementary to the technique of chlorosulfonation used to stain polyethylene in a similar way as bright field microscopy is to dark field.     

Surface modification of polypropylene: Hydrophilic finishing with carbohydrates

Conversion of hydrophobic polypropylene surfaces to hydrophilic, water wettable surfaces by adsorption of amphiphilic carbohydrates (“surfactant immobilization”) as well as by covalent bonding of sucrose residues via azid photolysis (“photochemical immobilization”) was investigated. Improvement of surface hydrophilicity was determined by contact angle measurements and application of special test inks for polyolefines.     

Inorganic-Organic Polymers as Migration Barriers Against Liquid and Volatile Compounds

In addition to the barrier properties against water vapor and oxygen, inorganic-organic polymers can also function as protection layers against unwanted migration of chemical substances in two ways. First, hybrid polymers prevent components from migrating out of polymer substrates. This is of special interest for polymeric materials containing substances like plasticizing agents, unreacted monomers or catalysts. Thus the olfactory nuisance and the toxicological emission are decreased. The plastics are also prevented from becoming prematurely brittle. Second, the coated materials are also protected against the interaction of dyes or dirt staining the material.These functions can be achieved by thermally or UV curable coating materials, synthesized by the sol-gel technique. Since several polymer materials show only a low heat resistance (e.g. PVC, polyolefines), this publication is focussed on the development of new migration barriers based on photochemically curable sols.Another advantage of the UV process in comparison to thermal treatments are the short curing times and low power consumption which make this process even more attractive for industrial applications. The coatings were characterized by IR and solid state NMR spectroscopy. The migration barrier properties were tested according to industrial standards.Due to the choice of specific functional groups, these hybrid polymers can be further modified in order to combine the migration barrier function with additional properties: scratch and abrasion resistance, hydrophobicity, antistatic effects. Examples of feasible combinations of properties are also given.     

等离子体处理云母对填充聚烯烃结构影响的研究

<正> 近年出现的用冷等离子体处理填料的方法被认为是偶联剂技术的一个新发展。它是通过等离子体作用,使填料表面产生有利于与基体树脂相容的结构变化,从而实现改善填充体系使用和加工性能的目的。这种处理方法具有作用强度大而穿透力小、效率高,无公害等特点。与采用硅烷、钛酸酯偶联剂等较成熟的处理方法不同,等离子体处理的研究尚在起步阶段,基本局限于对处理效果的探讨,有关处理对填充体系结构影响的研究尚不多见。本文以经乙烯等离子体处理的云母为填料,初步研究了填料与HDPE、IDPE及PS界面的水扩散特性、界面极化特性,以及基体的松弛转变行为。     

Polarized FT-IR photoacoustic spectroscopy on polymer fibers

The orientation of macromolecular chains in two melt-spun polymer fibers (segmented polyurethane elastomer and melt-modified polyolefine fibers) was studied by photoacoustic spectroscopy (PAS) with polarized light in the mid-infrared range. The PAS orientation functions calculated from the photoacoustic signal intensities of orientation sensitive bands describe the orientation of the different chain segments with respect to the fiber axis. Thus, the orientation of hard and soft segments in the unstressed polyurethane fiber is different and both are similiar to that of the corresponding injection molded bars. With increased spinning velocity an improved orientation of the polyolefine chains along the fiber axis, but only in the amorphous regions of the polymer, were detected. Only a slight reduction of orientation was measured as a result of the subsequent chemical crosslinking in the polyolefines.     

DSC Study of Oxidation Induction Periods

A theory of the evaluation of kinetic parameters of induction periods for non-isothermal processes is outlined and a method to obtain the parameters from non-isothermal differential scanning calorimetry measurements, based on the dependence of onset temperature of oxidation peak on heating rate, is presented. The applicability of the method is demonstrated on the study of oxidation induction periods of edible oils and polyolefines. In all cases, the parameters of an Arrhenius-like equation describing the temperature dependence of induction period have been obtained. It is shown that the method gives the parameters not affected by oxygen diffusion which are transferable to be used in modelling the non-isothermal induction periods where the effects of diffusion, heat transfer and evolution of reaction heat are explicitly involved. A method of estimating the residual stability after a thermooxidative stress of the material is suggested. This revised version was published online in July 2006 with corrections to the Cover Date.