【作者】 丛丽晓；

【导师】 冯圣玉；

【作者基本信息】 山东大学 ， 高分子化学与物理， 2008， 硕士

【摘要】 水性聚氨酯(WPU)是以水为主要分散介质的聚合物,具有机械性能良好、粘接强度大、柔韧性好、不燃、无污染、易加工等优点,是一种绿色环保型材料,得到了广泛的应用。但是WPU本身的耐水、耐溶剂性能不好,为了解决这些问题,需要对其进行改性。聚硅氧烷具有低温柔顺性好、热稳定性高、耐侯性和耐水性好等优异性能,用聚硅氧烷改性WPU可以得到性能优异的材料。一般采用羟基硅油改性WPU,但由于形成的是Si-O-C键型,所以耐水解性差。而用羟烃基封端聚硅氧烷则得到的是Si-C-O键型,耐水解性好。本文对双羟烃基封端聚硅氧烷改性水性聚氨酯进行了研究,制备了羧酸型的阴离子水性聚氨酯,并探讨了改性后的水性聚氨酯的性能。以溴乙烷、甲基三乙氧基硅烷为主要原料制备了四甲基四乙基环四硅氧烷。并用烯丙醇、四甲基二硅氧烷和四甲基四乙基环四硅氧烷为主要原料制备了一系列分子量在8000以下的双羟丙基封端聚甲基乙基硅氧烷(PEMS-OH)。用核磁和红外表征了PEMS-OH合成过程中的各步产物的结构。并用端基分析法、~1HNMR法分别测定了各种PEMS-OH的分子量。结果表明,两种方法得到的结果均与理论值很接近。以甲苯二异氰酸酯(TDI)、聚醚二元醇(PPG)、PEMS-OH、二羟甲基丙酸(DMPA)、乙二醇、丙三醇、三乙胺为主要原料,用丙酮法制备了阴离子型有机硅改性水性聚氨酯(PSU)。实验采用顺序加料的方式,即先加入PEMS-OH和TDI反应一段时间然后再加入PPG和其他组分继续反应。通过透射电镜(TEM)研究发现,PEMS-OH中PDS分子量大于4000、含量高于8%时,乳液中容易出现棒状聚集体,其他条件下出现球形或类球形聚集体。粒径测试结果表明,PSU和WPU乳液的平均粒径在400-500mm之间,大部分粒径分布比较集中,但也存在一些粒径达微米级的大粒子。扫描电镜(SEM)研究PSU胶膜断面形态发现,PSU胶膜随PEMS-OH含量和分子量的增加相分离增强,并且聚硅氧烷富集在PSU胶膜表面。机械性能测试表明,PEMS-OH分子量在2000-4000、含量在4%时,所得胶膜的力学性能最好。耐水耐溶剂性能测试表明,PEMS-OH分子量在4000、含量在8%时,胶膜的耐水性最好;而PEMS-OH分子量在2000、含量在8%时,胶膜的耐溶剂性能最好。通过热重分析(TG)发现,PEMS-OH分子量在2000左右、含量在4%左右,胶膜的耐热性最好。聚硅氧烷和聚氨酯的相容性不好,在相分离达到一定程度时,其耐水性,力学性能均有一最佳值,相分离继续增加,则性能变差。得到的PSU乳液属于单组分水性聚氨酯,与WPU胶膜相比,其胶膜的耐水性和耐甲苯性能得到很大的提高,而且力学性能也有所增强。这些优异的性能将使PSU乳液在涂漆、涂料、皮革涂饰剂、织物整理剂等方面得到广泛的应用。更多还原

【Abstract】 Waterborne polyurethane(WPU)is a dispersible polymer in water medium.WPU possess characteristic such as good mechanical capability, high adhesion strength,good flexibility,noncombustible,non-pollution, easy processing,so it is regarded as a kind of green and environment-friendly materials and widely used in many industries nowadays.However,WPU has poor the water resistance and solvent resistance,so it has to be chemically modified for its application. Polysiloxanes,with good low-temperature flexibility,thermal stability, weather resistance and excellent water resistance and good performance, could be used to modify WPU.Hydroxyalkyl terminated polysiloxanes were generally used to modify WPU.However,due to the formation of the Si-O-C bond in modification of WPU with these polysiloxanes,the material has poor hydrolysis resistance performance.When hydroxyalkyl terminated polysiloxanes are used to modify WPU,hydrolysis resistance performance can be reached because of the Si-C-O bond formation. Therefore,in the thesis,dihydroxyalkyl-terminated polysiloxanes are used to modify the WPU,and anionic acid type WPU was synthesized.At the same time,the properties of WPU were also explored.Tetramethyltetraethylcyclotetrasiloxane was prepared through reactions between bromoethane and methyltriethoxysilane.Meanwhile,a series of dihydroxypropyl-terminated polysiloxanes(PEMS-OH),with molecular weight below 8000,are prepared using allyl alcohol, tetramethyldisiloxane and tetramethyltetraethylcyclotetrasiloxane.The final and intermediate products in each process of PEMS-OH preparations were fully characterized by the FT-IR and NMR spectra.The molecular weights of PEMS-OH were estimated by end-group analysis and ~1HNMR respectively.Good agreements between the theoretical molecular weights and those obtained from end-group analysis and ~1HNMR are obtained.The anionic WPU modified with PEMS-OH were prepared from toluene diisocyanate,polypropylene glycol,PEMS-OH, dimethylolpropionic acid,ethylene glycol,glycerol,and triethylamine through acetone method.Experiment was implemented by the gradual addition method.First PEMS-OH and TDI were added to the flask to react. After a period of time,the PPG and other components were put into the flask in form.The target product was investigated by transmission electron microscope(TEM).When the molecular weight of PEMS-OH was higher than 4000 and the content is above 8%,rod shaped aggregates were observed.In the rest of the experiments,spherical or spheroid aggregates were found.The results of the size and the size distribution of particles show that the mean particle diameter of WPU and PSU is about between 400 nm and 500 nm.The distribution of most of particle size is relatively concentrated,however,micron sized large particles were also detected. The morphologies of fractured section of PSU films are observed using scanning electron microscope(SEM).The results show that phase separation in PSU films increases with the increase in PEMS-OH content and its molecular weight,and polysiloxane enriches in PSU film surface. Mechanical property tests show that better performance can be obtained when the molecular weight of PEMS-OH is between 2000 and 4000 and its content at 4%.Water and solvent resistant properties test show that the material has better water-resistant performance when the molecular weight of PEMS-OH is 4000 and its content at 8%,while the better solvent-resistant performance appears when the molecular weight of PEMS-OH is 2000 and its content at 8%.Thermal gravimetric analyses (TG)indicate that the material has better heat-resistant performance when the molecular weight of PEMS-OH is about 2000 and its content at 4%. Polysiloxane and PU have the poor compatibility.When the phase separation reaches a certain level,its water-resistance,and mechanical properties are in an optimum value.As the phase separation continues to increase,the performance deteriorated.The PSU belongs to monocomponent WPU emulsion.Compared with WPU film,PSU film has the better water resistance,solvent resistance and mechanical properties.Own to these high-performances,PSU emulsion can be widely applied in painting,coating,leather finishing agent,fabric finishing agent,etc.更多还原