封闭型异氰酸酯的反应机理与应用

封闭型异氰酸酯是一类在室温下能保持端异氰酸酯基团的封闭,而在适当的条件下（如一定的高温）能够发生解封反应,释放出-NCO基团的聚氨酯树脂。着重从端-NCO基团的封闭-解封反应机理、封闭剂种类、解封温度的影响因素和研究方法以及封闭型异氰酸酯在水性聚氦酯上的应用进展等方面做一个讨论。     

甲乙酮肟封闭聚氨酯预聚体的研究

首先用聚己二酸-1,4-丁二醇酯二醇和甲苯二异氰酸酯(TDI)制备端异氰酸酯预聚体,然后用甲乙酮肟封闭预聚体的异氰酸酯基团。用化学分析方法研究了封闭反应温度、反应时间以及物料的配比对异氰酸酯基团封闭率的影响,用红外光谱仪研究了封闭前、封闭后和加热解封后的预聚体异氰酸酯基团特征吸收峰的变化。实验结果表明:随反应温度的升高、反应时间的增加或N(活泼-H)/N(-NCO)增加,异氰酸酯基团封闭率增大;在80℃,N(活泼-H)/N(-NCO)=1.2,反应4 h的条件下,甲乙酮肟可完全封闭异氰酸酯基团;甲乙酮肟封闭的聚氨酯预聚体能在135℃下解封。     

封闭型水性多异氰酸酯固化剂的制备及其性能研究

利用甲乙酮肟（MEKO）与IPDI三聚体反应并接枝聚乙二醇单甲醚（MPEG）制备了封闭型水性多异氰酸酯固化剂，采用红外光谱仪、热失质量仪和透射电镜等设备研究了该固化剂的结构、解封温度及胶束形态，同时考察了固化剂对羟基型水性聚氨酯树脂的固化效果及其混合乳液的贮存稳定性。结果表明，该水性固化剂的解封温度在95～249℃之间，最佳使用温度在160℃左右；该固化剂可明显改善羟基型水性聚氨酯膜的耐水、耐溶剂及力学性能，另外固化剂与水性聚氨酯的共混乳液具有良好的贮存稳定性。     

一种封闭型多异氰酸酯树脂的合成

以3,5-二甲基吡唑、甲乙酮肟为封闭剂,制备解封温度较低的110～120℃封闭型多异氰酸酯;讨论了封闭剂种类,活性氢与异氰酸酯基团的量之比、反应温度、反应时间对封闭反应的影响;探讨了封闭物的解封反应,确定其解封温度.用红外光谱比较了封闭前后和加热解封后的预聚体的差别.     

丁酮肟封闭多亚甲基多苯基多异氰酸酯的研究

以丁酮肟为封闭剂,制备了封闭型多异氰酸酯树脂;通过实验,讨论了丁酮肟与异氰酸酯基团的摩尔比、反应温度、反应时间对封闭反应的影响;并通过红外光谱研究了封闭产物解封温度。结果表明,最佳反应条件为n(丁酮肟)/n(-NCO)为1.2,反应温度60℃,反应3 h,且封闭物在120℃左右可以解封。     

封闭剂用于非异氰酸酯预聚体扩链制备聚氨酯弹性体材料的研究

使用甲乙酮肟和苯酚分别对聚醚型聚氨酯预聚体进行封端,然后与端氨基非异氰酸酯基聚氨酯预聚体嵌段扩链,制备聚氨酯膜。分析了甲乙酮肟和苯酚的封端温度、解封温度和封端效果;分别考察了封闭剂对膜力学性能与热性能的影响。结果表明,差示扫描热量法显示苯酚和甲乙酮肟的封端反应温度分别为100 ℃和80 ℃;从封闭效果、膜的力学性能及环保角度分析比较,甲乙酮肟作聚醚型预聚体的封闭剂优于苯酚,甲乙酮肟封闭预聚体扩链后膜的拉伸强度为25.1 MPa,断裂伸长率为424 %;热重分析表明膜的热性能基本不受封闭剂种类的影响。     

封端型水性聚氨酯的合成与研究

以异佛尔酮二异氰酸酯(IPDI)、二羟甲基丙酸(DMPA)、聚醚多元醇(PPG、PTMG、PEG)等为主要原料进行反应,分别采用亚硫酸氢钠(NaHSO3)和甲乙酮肟(MEKO)封端,合成了系列水性聚氨酯乳液。讨论了多元醇类型及配比、不同封端剂对水性聚氨酯乳液及胶膜性能的影响。结果表明,由PPG-220合成的水性聚氨酯具有较好的耐水性,由PTMG2000合成的水性聚氨酯具有优异的力学性能,当PPG-220∶PTMG2000摩尔比为3∶1复配使用时所得的水性聚氨酯能达到优良的综合性能。以NaHSO3为封端剂其成膜性较好,解封温度为60.5~68.0℃;以MEKO为封端剂其稳定性较好,解封温度为110~124℃。     

新型合成革用高固含量聚氨酯胶黏剂的研制

制备了一种新型合成革用高固含量封闭型聚氨酯胶黏剂。该胶黏剂主剂以聚酯二醇PBDA-2300、PEBA-1000、甲苯二异氰酸酯(TDI)和封闭剂丁酮肟等为主要原料制备,固含量为80%;三乙烯四胺作为交联剂。研究发现,在NCO/OH摩尔比值为1.22~1.24时,主剂的黏度符合实际使用要求。该胶黏剂固化时氨基与解封的异氰酸酯的摩尔比值在1.0~1.4时,胶膜的强度最好。另外,用该胶黏剂配制的工作浆可于48 h内符合生产需求。     

水性聚氨酯胶黏剂发展概况

简述可水分散性多异氰酸酯胶黏剂、乙烯基聚氨酯水性胶黏剂和水分散性聚氨酯(PUD)胶黏剂等水性聚氨酯胶黏剂国内外应用和技术发展状况,对我国水性聚氨酯胶黏剂的发展提出初步看法和建议。     

聚醚二元醇与异氰酸酯封端反应的研究

以聚醚二元醇和二苯甲烷二异氰酸酯(MDI)为原料合成预聚体,分别以丙酮肟、甲乙酮肟、丁二酮肟和硝基甲烷作为封闭剂,制备了二苯甲烷二异氰酸酯固化剂。用于阴极电泳涂料,以降低固化温度。利用化学滴定、红外光谱和热重分析(TG)等分析手段对预聚体和异氰酸酯固化剂进行了表征和分析。实验结果表明解封反应时间及解封温度与封闭剂种类有关,甲乙酮肟封闭的异氰酸酯固化剂的解封温度最低,为130℃,解封时间为20 min。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料，介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比，介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序，对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.