【作者】 刘志勇；

【导师】 蹇锡高； 王锦艳；

【作者基本信息】 大连理工大学 ， 材料学， 2007， 博士

【摘要】 近年来，随着环境污染日益严重，水性涂料已经成为世界共同关注的低挥发性有机物（Volatile Organic Compounds，VOC）排放涂料的研究热点。但是，大多数水性涂料由于耐热性能差而限制了它们的应用范围，采用耐高温树脂制备耐热水性涂料则是重要的方法之一。然而由于耐高温树脂的刚性结构，难以获得稳定的水分散体系，极少有基于这类树脂的耐热水性涂料的文献报道。因此，本论文尝试设计一些新方法应用于耐热水性涂料的制备，以期为将来工业化生产和应用提供理论依据。新型含二氮杂萘酮联苯结构的聚芳醚腈酮（PPENK）是本课题组863计划重大项目成果之一，是目前耐热等级最高的可溶性聚芳醚新品种，性能价格比优异，具有很好的应用前景。为了制备耐热水性涂料，通过水解反应对PPENK进行亲水改性，经FT-IR和¹H-NMR表征证实PPENK分子中的氰基转化为亲水性基团COOH或CONH₂，对三个不同反应时间的水解产物HPPENKa（0.5 h），HPPENKb（1.5 h）和HPPENKc（3.5 h）分别进行了性能测试和分析。结果显示，随着反应时间的延长，水解产物的氰基转化率增加，玻璃化转变温度（T_g）略有增加，但热失重温度下降，水解产物的亲水性能得到较大改善，比如当氰基转化率为93.82％时，水解产物的水接触角为54.4°，而PPENK为75.3°。研究了水解反应的动力学，在反应温度为100℃、110℃、120℃和130℃时，反应表观速率常数分别为7.2×10^-3 min^-1、1.0×10^-2 min^-1、1.5×10^-2 min^-1和2.2×10^-2 min^-1，反应的表观活化能为47.8 kJ／mol。通过研究反应共溶剂、反应温度和NaOH浓度对水解反应的影响，得到优化的工艺条件如下：反应温度为120℃，6mol／LNaOH溶液，反应共溶剂为DMAc。制备了基于上述三种亲水改性树脂的水分散体，其稳定性如下：HPPENKc＞HPPENKb＞HPPENKa。其中，基于HPPENKc的水分散体具有较好的分散稳定性和成膜性能；优选出了适用于HPPENK水分散体的固化剂和乳化剂。HPPENKc固化膜性能如下：铅笔硬度（6 H）、耐热性能（300℃，24 h）、耐冲击性能（50 cm）以及附着力（1级）。从分子设计出发，以甲苯-2，4-二异氰酸酯（TDI）、二羟甲基丙酸（DMPA）、聚乙二醇（PEG）和4-（4’-羟基苯基）-2，3-二氮杂萘-1-酮（DHPZ）为主要原料，用阴离子自乳化法制备了一系列新型聚氨酯水分散体（Polyurethane dispersions，PUDs）涂料。红外测试结果显示二氮杂萘酮联苯结构已被成功引入到聚醚型聚氨酯分子主链中，当PEG分子量分别为570、1000和2000时，DHPZ的含量（投料质量比，下同）分别小于18.06％、22.98％和20.07％时，均可得到较稳定的水分散体，超过这个值则难以实施分散。所得水分散体固含量在22.3～31.2％之间，粒径和粘度随着DHPZ含量的增加而增大；PEG的分子量越大，水分散体的粒径和粘度越大。将二氮杂萘酮联苯结构引入到聚氨酯分子中增加了分子链的刚性，改善了涂层的耐热性能。如DHPZ含量为18.06％的PU-A4样品，其分子硬段T_g达到263℃、5％热失重温度为252℃，远高于不含二氮杂萘酮联苯结构聚氨酯的同类数值。随着PUDs中DHPZ含量的增加，固化膜的吸水率下降、水接触角增大、拉伸强度增大、断裂伸长率下降；随着PEG分子量增大，固化膜的吸水率增加、水接触角减小，拉伸强度增加、断裂伸长率减小。通过调节DHPZ和DMPA的含量（投料质量比，下同）和PEG的分子量，可开发出不同耐热等级的综合性能良好的新型聚氨酯水性涂料，具有广阔的应用前景。采用相反转乳化法制备了基于未改性PPENK（η=0.51 g／dL，CHCl₃）的水分散体。设计了四因素三水平（L₉（3⁴））的正交试验，考察了聚乙烯醇（PVA）水分散液的浓度、PPENK的氯仿溶液浓度、PVA对PPENK的承载率(树脂质量比：W_PVA／W_PPENK)以及分散机的转速等因素对于水分散体性能的影响。结果表明，试样PD-4具有较好的综合性能，其工艺条件为：PVA水分散液的浓度为2.5％、PPENK的氯仿溶液浓度3.0％、PVA对PPENK的承载率(树脂质量比：W_PVA／W_PPENK=1.25)以及分散机的转速为3000 r／min。PD-4乳液中PPENK微粒粒径在365～666 nm之间，透射电镜观察到微粒形貌有分形的特性，在水相中具有较好的分散性能；PD-4水分散体具有良好的成膜性能，在180℃固化条件下，PD-4涂膜的附着力为1级、铅笔硬度为6 H、冲击强度为50 cm，可以在270℃条件下长期使用。通过超临界反溶剂（SAS）过程，成功得到了平均粒径为170～400 nm的PPENK微粒，证明制备PPENK直接水分散涂料是完全可能的。当PPENK／CHCl₃溶液浓度为10.0％时是一个上限值。在操作压力10MPa-12MPa范围内，温度35℃，CO₂流速1.0 m³／h以及PPENK／CHCl₃溶液流速4 mL／min时，PPENK／CHCl₃浓度为3.0％时的微粒粒径小于浓度为1.0％时的粒径；压力的变化和微粒粒径的大小关系显得较为复杂。当温度为35℃，PPENK／CHCl₃溶液浓度为1.0％，PPENK／CHCl₃溶液流速为4 mL／min以及CO₂流速为1.0 m³／h时，微粒粒径在9 MPa-17 MPa操作压力范围内，呈现先增大后减小的趋势。当PPENK／CHCl₃浓度为3.0％时，操作压力9 MPa-12 MPa实验范围内，压力对粒径的影响趋势与浓度1.0％时大致相同。聚合物微粒具有分形的特性。更多还原

【Abstract】 In recent years, with the environmental pollution becoming serious, water-borne coating has been a topical subject for low volatile organic compounds （VOC） coating. However, most of them have low heat-resistant temperature that means their applications are limited in certain areas. In order to obtain heat-resistant waterborne coatings, one of the important ways is to use some heat-resistant resins. But it is difficult to obtain a finely dispersed system due to their rigid structures. Therefore, few papers have been reported on aqueous dispersions based on these resins. In this paper, several novel methods are designed and applied in preparing heat-resistant waterborne coatings, which are theoretical foundations in their industrialization and application in the future.Poly（phthalazinone ether nitrile ketone）s （PPENK） containing phthalazinone moieties developed by our group is one of the scientific achievements of Hi-tech Research and Development Program of China. PPENK has much better heat resistance and solubility than similar high performance polymers. For better properties, the polymers have a strong competitive capability in international market. PPENK is modified in a hydrolysis reaction in order to prepare heat-resistant waterborne coatings. The CN groups of PPENK are successfully converted into hydrophilic groups, COOH or CONH₂, which give macromolecule hydrophilicity. The structures of hydrolyzates （HPPENK） are confirmed by FT-IR and ¹H-NMR. The properties of hydrolyzates in different reaction time, HPPENKa （0.5 h）, HPPENKb （1.5 h） and HPPENKc （3.5 h）, are measured. The results indicate that the nitrile groups conversion ratio increases, glass transition temperature （T_g） of hydrolyzates increases slightly whereas the weight loss ratio of HPPENK decreases as hydrolysis time is prolonged. As expected, the hydrophilicity of HPPENK is improved greatly, e.g. when CN conversion ratio is 93.82 %, the water contact angles are decreased from 75.3°of PPENK to 54.4°of HPPENK. The kinetic of hydrolysis reaction is studied. When the reaction temperature are 100℃、110℃、120℃and 130℃, the apparent first-order rate constant K_ap1 for hydrolysis of PPENK are 7.2×10^-3 min^-1、1.0×10^-2 min^-1、1.5×10^-2 min^-1和2.2×10^-2 min^-1, respectively. The activation energy for the hydrolysis reaction is determined as 47.8 kJ/mol （CN）。By studying the effect of the different reaction co-solvents, reaction temperature and NaOH concentration on hydrolysis, the optimal synthetic technique could be concluded that it is of 6 mol/L NaOH solution and DMAc as co-solvent at 120℃. Aqueous dispersions based on three modified resins were prepared and their stability was in the following order: HPPENKc＞HPPENKb＞HPPENKa. Especially, the HPPENKc aqueous dispersion played good stability and good film-forming property. Curing agents and emulsifiers are screened and applied in HPPENKc aqueous dispersion. Cured film properties of HPPENKc were as follows: pencil rigidity （6 H）, heat-resistance （300℃, 24 h）, impact-resistance （50 cm） and adhesion （grade 1）.From the molecular design, a series of novel aqueous polyurethane dispersions （PUDs） were synthesized by cation self-emulsification. The main raw materials were TDI, PEG, TEA and DHPZ. The FT-IR spectra confirmed that the phthalazinone segments were introduced into the main chain of polyurethane. Under the same conditions, stable PUDs are obtained when molecular weight of PEG were 600, 1000 and 2000, and the tiptop content of DHPZ （Feeding weght ratio） were 18.03 %, 22.97 % and 20.03 %, respectively. The emulsion could not be dispersed if the tiptop content of DHPZ was exceeded. The solid content of PUDs was between 22.3～31.2 %. The particle size and viscosity of PUDs increased with DHPZ content, the same conclusion as PEG molecular weight.The rigidity of polyurethane chain is enhanced and heat-resistance of cured films was improved due to the aromatic structure of the phthalazinone moiety. As to PU-A4 with 18.06 % DHPZ content, the T_g and 5 % weight loss temperature of hard segments were 263℃and 252℃, respectively, outclass the PUDs without DHPZ. With the DHPZ content increased, the water contact angle, hardness and tensile strength of cured films increased, in contrast, water swell, impact resistance and elongation at break decreased significantly. With the PEG molecular weight increased, the water contact angle, hardness and tensile strength of cured films decreased, in contrast, water swell, impact resistance and elongation at break increased. According to different applications, the novel PUDs with different heat resistant class and perfect combination properties could be exploited by controlling the molecule weight of PEG and content of DHPZ and DMPA.Phase inversion emulsification is applied in preparing aqueous dispersion based on PPENK （η=0.51 g/dL, in CHCl₃） without any modification. The orthogonal layout of four factors and three levels （L₉（3⁴）） was designed to study the effect of concentration of PVA/water, concentration of PPENK/CHCl₃, W_PVA/W_PPENK, and stirring velocity on properties of dispersions. Among the formulations, PD-4 played perfect combination properties. The optimal technology of PD-4 was as follows: 2.5 % PVA/water, 3.0 % PPENK/CHCl₃, W_PVA/W_PPENK=1.25, and 3000 r/min rotational speed of dispersion machine. PD-4 emulsion played good stability. The particle size of PPENK micro-particle was 365～666 nm. The micro-particles of PPENK could be observed fractal characteristic by TEM and stably dispersed in water phase. PD-4 aqueous dispersion played perfect film-forming property and its cured film baked in 180℃showed adhesion（1 grade）, pencil hardness（6H） and impact resistance （50cm）. The cured film of PD-4 could be used at 250℃for a long time.Supercritical anti-solvent （SAS） process was applied to preparation of PPENK micro-particle of mean particle size 170～400 nm when chloroform and supercritical CO₂ were used as organic solvent and anti-solvent, respectively. This confirmed that it was possible to prepare aqueous dispersion based on the micro-particle. Upper limit value of PPENK/CHCl₃ concentration was 10.0%. When PPENK/CHCl₃ concentration was 3.0 %, particle size of PPENK micro-particle was less than that of 1.0 % PPENK/CHCl₃ at the follow operation conditions: 10 MPa-12 Mpa, 35℃, CO₂ velocity of flow 1.0 m³/h, and PPENK/CHCl₃ solution velocity of flow 4 mL/min. The experimental data indicated that it was a complex relationship between pressure variation and particle size. Keeping the other operation conditions, particle size of PPENK micro-particle was shown the variation trend of from increase to decrease when operation pressure was 9 MPa-17 MPa. When PPENK/CHCl₃ concentration was 3.0% and operation pressure was 9 MPa-12 MPa, particle size of PPENK micro-particle was similar as that of 1.0 % PPENK/CHCl₃. The polymer micro-particles possessed fractal characteristic.更多还原