【作者】 娄春华；

【导师】 顾继友；

【作者基本信息】 东北林业大学 ， 生物材料工程， 2011， 博士

【摘要】 为实现功能性交联剂(稳定化异氰酸酯)与水性高分子共混或共聚创生新型单组分水性胶黏剂,本文采用2,4,6-三氯苯酚(2,4,6-TCP)作为封闭剂对多亚甲基多苯基异氰酸酯(PAPI)封闭的方法制备低温解封的封闭型异氰酸酯作为功能性交联剂。首先,本文采用一氯代苯酚(2-氯苯酚/邻氯苯酚和4-氯苯酚/对氯苯酚)作为封闭剂分别封闭常用的甲苯二异氰酸酯(TDI),系统地研究了邻/对氯苯酚封闭异氰酸酯的各个影响因素,详细讨论了封闭剂与异氰酸酯基的摩尔比、封闭剂结构、封闭反应温度、封闭反应时间、催化剂、反应介质对封闭反应的影响。采用二正丁胺回滴法、傅里叶转换红外光谱分析等方法对封闭结果进行了表征,并对封闭产物的稳定性进行了研究。其次,选用性能更佳、毒性较低的多亚甲基多苯基异氰酸酯作为原料,分别采用氯代苯酚(2-氯苯酚/邻氯苯酚和4-氯苯酚/对氯苯酚)和二氯代苯酚(2,4-二氯苯酚和2,6-二氯苯酚)作为封闭对其进行封闭,结果表明,二氯代苯酚由于其酚羟基的邻、对位较一氯代苯酚的又多了一个吸电子取代基,封闭反应的速率加快。确定酚羟基邻、对位全部由吸电子基团Cl原子取代的2,4,6-三氯苯酚作为最终的封闭剂对PAPI进行封闭,以实现低温解封闭的目的。讨论了—OH与——NCO的摩尔比、反应温度、溶剂、反应时间、催化剂等因素对异氰酸酯封闭反应的影响,利用红外光谱分析手段进行了表征。结果表明：较适宜的封闭剂与异氰酸根的摩尔比为(1.1～1.2)：1；升高温度有利于封闭反应的进行,较佳的反应温度为80℃；极性溶剂有利于封闭反应的进行,溶剂的极性越大,封闭反应越容易进行；延长反应时间,有利于封闭率的增加,但到一定程度,反应趋于平衡；添加有机锡类催化剂能大大提高封闭反应的速率,缩短封闭反应时间。并对封闭物进行了1H NMR和13C NMR表征,结果表明：产物中存在着氨基甲酸酯键。本文还建立了直接红外光谱法测定异氰酸酯封闭率的方法。利用848cm-1处的四取代苯环上两个孤立氢原子C—H面外变形特征吸收峰做定量分析峰,以红外光谱法计算体系中残留的异氰酸酯基的含量,该法具有简便、量小、准确、快速的特点,具有一定的实际应用价值。本文对封闭型异氰酸酯试样选择不同的条件,对其用邻甲苯胺法进行升温解封测试最低的解封温度。探讨了封闭异氰酸酯的解封闭温度以及影响封闭产物解封闭的主要因素,如不同解封溶剂、催化剂、升温速率等。FTIR谱图揭示出随着解封闭反应的进行,2250cm-1处的——NCO基团的特征吸收峰增强。热分析结果表明,2,4,6-三氯苯酚封闭PAPI封闭物的初始解封温度为75℃。试验结果表明：存在极性溶剂的条件下进行解封反应,所得最低的解封温度要比热分析得出的解封闭温度低很多。采用自乳化法合成水性化2,4,6-三氯苯酚封闭的PAPI,并利用激光粒度仪和扫描电子显微镜进行表征。激光粒度和扫描电镜分析结果表明,封闭异氰酸酯乳化后形成的乳胶粒为圆球状,并且以氢氧化钾为中和剂制备的水性封闭异氰酸酯乳液平均粒径小,但粒径分布宽,而以三乙胺为中和剂制备的平均粒径大,粒径分布窄；通过DSC测试,发现该封闭产物的起始解封温度为70℃,并且在120℃时能够完全解封。最后,利用DSC法研究了水性高分子-封闭异氰酸酯体系的反应机理,结果表明,对于乳白胶-封闭异氰酸酯体系,其动力学参数△E=4.190kJ/mol,n=0.7;对于聚乙烯醇-封闭异氰酸酯体系,其动力学参数△E=14.483kJ/mol,n=0.87。更多还原

【Abstract】 In order to achieve novelty one-component aqueous polymer-isocyanate adhesive, functionality curing agents, stabilization isocyanats, were blended or copolymerized with aqueous adhesive. In this paper, low temperature deblockable blocked-isocyanate, i.e., functionality curing agent, was prepared by2,4,6-trichlorophenol (2,4,6-TCP) blocked polymethylene polyphenlene isocyanate (PAPI).Firstly, on the basis of the previously study, we studied systematicly the various influencing factors when P-chlorophenol and O-chlorophenol blocked toluene diisocyanate (TDI), and discussed the effects of molar ratio of blocking agents and isocyanate, the structure of blocking agents, blocking reaction temperature, blocking reaction time, catalyst, reaction medium on the blocking reaction. The blocked adducts were characterized by the methods of di-n-butylamine back titration and Fourier transform infrared (FTIR) spectroscopy. And stability of blocked adducts was studied.Next, PAPI was checked as reagent because of its better performance and lower toxicity than TDI, which was blocked by blocking agents such as2-chlorophenol,4-chlorophenol,2,4-dichlorophenol and2,6-dichlorophenol. The experimental results showed that the reaction velocity of dichlorophenol as blocking agent was faster than that of monochlorophenol, since one more attracting electron substituent group, Cl atom, was at adjacent and contraposition of phenol hydroxyl.2,4,6-trichlorophenol was selected as a final blocking agent of polymethylene polyphenlene isocyanate to the purpose of low temperature deblocking. The effects of molar ratio of—OH/—NCO, reaction temperature, solvent, reaction time and catalyst on this blocking reaction were discussed. Fourier transform infrared was used to characterize these blocking adducts. Experimental results showed that it was propitious to the blocking reaction when the optimal molar ratio of-OH/-NCO was (1.1-1.2):1and the optimal reaction temperature at80℃. Meanwhile, experimental results also exhibited that the polar solvents could accelerate the blocking reaction and the reaction velocity was faster when the solvent polarity was stronger, and that it made for increasing blocking rate when the reaction time was prolonged, but to some extent, the reaction reached the equilibrium. In addition, experimental results also showed that the catalysts of organic tin could quicken significantly the blocking reaction velocity and reduced the blocking reaction time. TCP-blocked PAPI adduct was characterized by1H NMR and13C NMR. The results showed that there was-NH/-COO—formed in adducts.The method that determine blocking ratio using Fourier transform infrared was founded in this paper. The quantitative analysis peak was checked the characteristic absorption peak of the two isolated H on the four-substituent benzene which was at848cm-1. Then the rudimental content of—NCO was calculated. This method was of easy, little quantity, precision and rapidness.In different conditions, o-toluidine method was used to test the deblocking temperature of blocked isocyanate. It was discussed that the deblocking temperature of blocked isocyanate and the key influencing factors of deblocking, such as different solvents, catalyst and heating velocity, etc. Deblocking temperature was analyzed by DSC instrument, Fourier Transform Infrared Spectroscope and Thermal Gravimetric Analysis. The FTIR results showed that the characteristic absorption peak of—NCO which was presented at2250cm-1was increased gradually along with the deblocking reaction. The thermal analysis indicated that the initial deblocking temperature of2,4,6-TCP blocked PAPI was75℃. And the experimental results showed that the deblocking temperature would be declined when the blocked adduct in polar solvents.The emulsifiable2,4,6-TCP blocked PAPI was synthesized by the method of self-emulsification. The shape and size of the latex particles waterborne blocked isocyanates were characterized by laser particle size analysis instrument and scanning electron microscope (SEM). The results showed that, when TEA was neutralizing agent, the latex particle size was larger and distribution was narrower than that of KOH was neutralizing agent. And differential scanning calorimetry was showed that the blocking adduct was deblocked at70℃and deblocked perfectly at120℃.Finally, the curing mechanism of aqueous polymer-blocked isocyanate was studied by differential scanning calorimetry. The experimental results demonstrated that the dynamic parameters were deduced that ΔE=4.190kJ/mol, n=0.7for the system of poly vinyl acetate emulsion adhesive-blocked PAPI and ΔE=14.483kJ/mol, n=0.87for polyvinyl alcohol-blocked PAPI.更多还原