首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 140 毫秒
1.
反应条件对水性聚氨酯预聚反应的影响   总被引:4,自引:0,他引:4  
李士杰  廖水姣  李建宗 《粘接》2001,22(3):11-12,18
以TDI、N210、DMPA为基本原料,用丙酮法合成了稳定的聚氨酯乳液(WPU)。探讨了反应温度、溶剂、催化剂及用量对预聚反应的影响。结果表明:以丙酮为溶剂,以二月桂酸二丁基锡为催化剂(用量0.03%),反应温度80℃最为适宜。  相似文献   

2.
《聚氨酯》2004,(2):51-51
以TDI、N210、DMPA为基本原料,用丙酮法合成了稳定的聚氨酯乳液(WPU)。探讨了反应温度、溶剂、催化剂及用量等影响因素对预聚反应的影响。结果表明,以丙酮为溶剂,以二月桂酸二丁基锡为催化剂、反应温度80℃最为适宜。  相似文献   

3.
阴离子水性聚酯聚氨酯乳液预聚反应条件的研究   总被引:2,自引:0,他引:2  
采用聚酯多元醇(JW2503),甲苯二异氰酸酯(TDI),二羟甲基丙酸(DMPA)为基本原料,用丙酮法合成了稳定的聚酯型阴离子水性聚氨酯乳液。探讨了反应温度、反应时间、溶剂、催化剂及用量对预聚反应的影响。实验结果表明,以丙酮为溶剂,催化剂二月桂酸二正丁基锡的用量为0.03%,反应温度65℃最为适宜,反应时间为2h。  相似文献   

4.
刘建武  张跃 《精细化工》2021,38(5):1074-1080
液相条件下,以丙酮、氨水和双氧水为原料,钛硅分子筛(TS-1)为催化剂,溴化钠为助催化剂,叔丁醇为溶剂,在具有特殊微结构的连续流微通道反应器(AFR)中一步氧化合成了丙酮肟.考察了双氧水质量分数、氨水/丙酮物质的量比、双氧水/丙酮物质的量比、溶剂/丙酮物质的量比、催化剂和助催化剂用量、温度以及停留时间对氨肟化的影响.结果表明,AFR出口压力500 kPa、反应温度100℃、n(氨水):n(双氧水):n(叔丁醇):n(丙酮)=3.0:1.1:6.0:1.0、双氧水质量分数70%、氨水质量分数25%、催化剂用量8 g(以58.08 g丙酮的质量为基准,下同)、助催化剂用量3 mg、停留时间72 s条件下,丙酮转化率为75.7%、丙酮肟选择性和收率分别为96.8%和73.5%.AFR具有持液量小、停留时间短、强传质传热等特点,强化了反应物料和催化体系之间的协同效应,提高了氨肟化反应速率.  相似文献   

5.
冉利  张仕禄  阴新强 《工业催化》2013,21(10):66-70
合成了丁基碲盐,以丁基碲盐为催化剂,采用不同结构的醛作为反应物,合成α,β-不饱和化合物,考察反应溶剂、催化剂用量、反应温度、碱用量和反应时间,选择最佳反应条件。最佳反应条件为:溶剂为四氢呋喃和H2O,其用量分别为5 mL和0.04 mL,温度70 ℃,碱用量为反应物(醛)的2倍,催化剂用量0.05 mmol,反应时间24 h,此条件下,反应产率超过90%, 产物中E型结构达到98%,实验证明该催化剂可作为叶立德反应的高效催化剂,产率高,立体选择性好,反应后处理简单。  相似文献   

6.
杨春华 《工业催化》2010,18(8):61-64
探索了生物质甘油在铜铬催化剂作用下催化转化为羟基丙酮的反应条件,采用乙醇为溶剂,考察了甘油浓度、催化剂用量和反应温度等因素的影响。较优反应条件:反应温度240℃,采用连续滴样的进样方式,甘油浓度80%,未还原的铜铬催化剂[n(Cu)∶n(Cr)=1]用量为原料质量的2.5%,甘油转化率和羟基丙酮选择性分别达到95.4%和89.9%。  相似文献   

7.
液相法合成异佛尔酮反应研究   总被引:1,自引:0,他引:1  
董宇航  陈文强  宋琦  裴玲  赵伟  吕培 《广州化工》2011,39(15):89-91
研究以丙酮为原料液相法合成异佛尔酮的液相缩合反应动力学。考察了以氢氧化钠为催化剂时,催化剂浓度、压力、温度、反应时间对反应的影响,结果表明该反应温度215~220℃、丙酮与水质量比3∶1、催化剂用量0.13 mol NaOH、压力3.8~4.5 MPa下反应3 h为最优反应条件。  相似文献   

8.
以固体酸作为催化剂,以甘油和丙酮为原料合成丙酮缩甘油,考察了反应温度、反应时间、反应物配比、催化剂用量对反应的影响。实验结果表明,甲苯为带水剂,催化剂用量为甘油质量的6%,原料n(甘油)∶n(丙酮)为1∶3,反应时间为6 h,反应的温度为80℃,丙酮缩甘油的产率可达80%。本文采用固体酸作为催化剂,产品易分离且无需除酸,后处理简单。  相似文献   

9.
以苄叉丙酮和醛为原料,氢氧化钠水溶液为催化剂,采用两条路线合成了(1E,4E)-1-(4-溴苯基)-5-苯基-1,4-戊二烯-3-酮。考察了物料比、催化剂及其用量、反应温度、溶剂等因素对反应产率的影响。实验结果表明:苄叉丙酮与醛的物料比为1∶1.05,5%NaOH水溶液30 mL为催化剂,15 mL乙醇为溶剂,室温下进行反应。产率分别为84.6%和89.3%。通过熔点、IR和1H NMR确定了产物的结构。  相似文献   

10.
壳聚糖钯催化剂在合成有机酮反应中的催化作用研究   总被引:5,自引:1,他引:4  
吴春  聂芊 《化学与粘合》2004,(1):26-27,40
以壳聚糖为载体,负载金属Pd作为催化剂,研究了其对酰氯和三丁基锡化合物偶联反应的催化活性,详细考察了影响反应的各种因素,得出反应的最佳条件:有机锡试剂与酰氯的用量都是10mmol,催化剂用量0.2g。溶剂丙酮用量20ml。反应时间20h。催化剂可以重复使用,催化剂循环使用5次,偶联反应的产率仍为50%。  相似文献   

11.
12.
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.  相似文献   

13.
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.  相似文献   

14.
15.
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.  相似文献   

16.
17.
18.
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.  相似文献   

19.
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。  相似文献   

20.
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.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号