核壳结构水性丙烯酸树脂乳液的可控制备及其流变行为研究

发布时间：2018-05-02 07:00

本文选题：核壳结构 + 水性丙烯酸树脂　；参考：《武汉大学》2015年博士论文

【摘要】：涂料是典型且复杂的胶体体系,一般由成膜树脂、颜填料、助剂以及溶剂组成。涂料在我们的生产生活中无处不在,它涂装于底材表面,在赋予材料美丽外观的同时,也起到关键的保护作用。随着科技进步和环保法规的日益严格,全球涂料工业整体在向环保型涂料转变,我国的涂料工业目前也正处在这一关键转型期。我国是一个涂料大国,2014年涂料产量世界第一。但我国却并非涂料强国,以汽车涂料为例,我国的汽车产量连续六年世界领先,目前进入我国市场的众多合资品牌轿车已基本囊括世界各大著名汽车厂商,但为之配套的汽车涂料供应商却完全为国外企业所垄断(如阿克苏、BASF、立邦等)。即使是正在兴起的国产自主品牌轿车,所用涂料也基本是国外品牌。经过近三十年的发展,中国涂料技术取得了长足进步,溶剂型工业涂料水平已基本与国外公司相当,但在水性工业涂料领域,仍处于起步阶段。国内在水性涂料用高端原材料、关键树脂合成技术、配方应用方法以及施工工艺等诸多方面与国外涂料企业相比仍有巨大差距,这些都需要我们涂料研究者扎扎实实地进行系统而深入的研究与知识积累。汽车涂料通常代表着工业涂料技术的最高水平,而金属闪光漆作为目前全球最流行的汽车面漆,在其中扮演着重要角色。金属闪光漆体系通常需要低固含量和高触变性,以帮助金属粉定向排列并获得好的随角异色性能(FLOP INDEX)。但溶剂型金属漆在施工过程会排放大量有机溶剂污染环境,因此金属闪光漆的水性化是汽车涂料环保改造的重要环节,其中的关键技术是水性金属闪光漆体系的流变控制方法。本课题从常用的丙烯酸树脂乳液入手,系统研究其合成与结构调控技术,同时深入探究该水性树脂的流变特性及其影响因素,并将这种树脂进一步应用于水性金属漆中来制备汽车面漆,以期为开发具有自主知识产权的水性金属漆关键树脂奠定基础。整篇论文的结构框架可分为五个部分,以五个章节展开：第一章系统综述了水性丙烯酸树脂的历史与发展、合成方法及应用、水性金属漆的研究动态、流变控制问题以及水性涂料的流变控制方法,并提出自己的选题背景与研究思路。第二章主要涉及水性金属漆用核壳结构丙烯酸树脂的合成。以常见丙烯酸酯类单体为原料,过硫酸铵为引发剂,十二烷基硫酸钠(SLS)和烷基酚聚氧乙烯醚(OP-10)为复配乳化剂,采用核壳乳液聚合技术制备水性金属漆用丙烯酸树脂乳液。系统考察了反应温度、引发剂浓度、乳化剂配比及浓度对于反应转化率、粒径和分子量等的影响。结果显示小幅度的温度变化对反应转化率影响不大,随引发剂浓度从0.30%增加到0.62%,体系的转化率先增加后降低,而分子量却-直在下降,最适引发剂浓度在0.39%。乳化剂的用量和配比对反应转化率和粒径分布有很大影响。随复配的阴：非离子乳化剂中OP-10的增多,反应转化率下降的同时产物粒径增大,分布变宽,推测其原因可能是由于OP-10的乳化能力弱于SLS所致。在固定阴：非离子乳化剂(质量比)=1：0.5的情况下,随总乳化剂用量从1.0%增加到2.5%,反应转化率先增加后趋于平稳,并且乳液粒径分布变窄。优化各种影响因素得到最佳的合成路线为：SLS:OP-10=1:0.5,乳化剂浓度1.40%,引发剂浓度0.39%,反应温度76℃,体系转化率可达96.4%。由此所得树脂乳液采用电镜、红外、GPC、热重等进行了详细表征,并将其应用于水性金属漆配方中,获得良好的铝粉定向效果以及成膜性能,FI值为23.04。第三章以所开发的碱溶胀型核壳结构丙烯酸树脂乳液为模型,系统研究聚合物单体组分对于树脂增稠性能及粘弹性的影响规律。结果表明酸单体甲基丙烯酸(MAA)是树脂增稠的根源和主因,对于树脂的增稠和流变调控性影响最大。在固定其它组分含量不变的情况下,随羟基单体甲基丙烯酸羟丙酯(HPMA)用量的增加,树脂溶胀能力不断增强,体系粘度和模量都有小幅度增加；随核层软硬单体组成中软单体丙烯酸丁酯(BA)含量的增加,树脂的溶胀能力也在不断加强,但体系模量则先增加后减小,推测BA含量高时体系粘度不升反降的原因是聚合物结构强度降低所致。壳层软硬单体对于体系粘弹性的影响规律与核层-致。第四章是深入考察了水性金属漆用碱和助剂共增稠树脂乳液的制备及其增稠机理。碱(有机胺,如二甲基乙醇胺)溶胀型水性丙烯酸树脂乳液在中和后,由于羧基解离,聚合物链段溶胀增稠从而实现流变控制。但体系所用有机胺中和剂容易随着储存时间的延长或环境温度的升高而挥发,从而影响体系触变性甚至产品稳定性。为解决这一问题,本章设计合成壳层含有交联单体(二乙烯基苯)的核壳结构丙烯酸树脂乳液,该乳液直接加碱不会增稠,但加入少量成膜助剂乙二醇丁醚后却可显著增稠并具有强触变性。采用粒度仪、表面张力仪、流变仪以及扫描电镜等手段对该乳液在碱和助剂共同作用下的溶胀行为、界面性质、微观结构以及流变性质进行了详细的表征与研究,结果显示碱可以小幅度溶胀乳胶粒子,助剂不能溶胀粒子但可改变乳液界面性质从而使其发生絮凝,碱和助剂共增稠的机理是树脂碱溶胀能力和助剂絮凝效应的加和。这种碱和助剂共增稠分散体的流变性质可以通过固含量、中和度和助剂用量来调控,并且这种增稠分散体非常稳定,室温密封储存六个月无相分离,仍可以被很好剪切。第五章为验证碱和助剂共增稠机理的有效性与普遍性,我们将这种共增稠模式引入到常见的非核壳结构丙烯酸乳液体系,仅以甲基丙烯酸、丙烯酸丁酯和甲基丙烯酸甲酯三种单体利用乳液聚合技术制备出简单的丙烯酸共聚乳液。由于共聚物中大量羧基被包埋在粒子内部,乳液直接加碱中和也不能增稠,而继续加入乙二醇丁醚后体系可获得较强的增稠能力和触变性。研究显示树脂增稠的原因仍然是树脂碱溶胀能力和助剂絮凝效应的加和。对体系的流变性质进行进一步研究发现,树脂增稠能力同时受聚合物组成、助剂用量及其种类的影响。此外,将碱和助剂共增稠的模式引入到传统苯丙乳液体系,发现同样适用,推测该模式应具有一定普适性,还可以推广到乙丙乳液、醋丙乳液等其它水性丙烯酸乳液体系。
[Abstract]:Paint is a typical and complex colloid system, usually composed of film forming resin, pigments, fillers, auxiliaries and solvents. The coating is ubiquitous in our production and life. It is coated on the surface of the base material and plays a key protection role while giving the beautiful appearance of the material. With the progress of Science and technology and the increasingly strict environmental regulations, the global paint is becoming more and more strict. Industry as a whole is changing to environment-friendly coatings. China's paint industry is now in this key transition period. China is a big country in paint, the production of paint in 2014 is the first in the world. But China is not a powerful coating country. As an example of automobile coatings, China's automobile production has been leading the world for six years in a row, and many joint ventures have entered the market of our country. Brand cars have basically included the world's most famous automobile manufacturers, but the matching automotive coatings suppliers are completely monopolized by foreign enterprises (such as Akesu, BASF, Li bang, etc.). Even the emerging domestic independent brand cars are basically foreign brands. After nearly thirty years of development, China's coating technology has been obtained. The level of solvent based industrial coatings has been basically equal to that of foreign companies, but in the field of water-based industrial coatings, it is still in its infancy. There are still huge gaps in the high quality raw materials used in water-based coatings, key resin synthesis technology, formula application and construction technology, compared with foreign coatings enterprises. It is necessary for our coatings researchers to carry out systematic and in-depth research and knowledge accumulation. Automotive coatings usually represent the highest level of industrial coating technology, and metal flash paint plays an important role in the world's most popular automotive finish. The metal flash paint system usually requires low solid content and high thixotropy. In order to help the metal powder to arrange and obtain the good FLOP INDEX, the solvent type metal paint will discharge a large amount of organic solvent pollution in the construction process, so the water character of the metal flash paint is an important link in the environmental protection reform of the automobile coatings, and the key technology is the rheological control of the water based metal flash paint system. Methods. From the common acrylic resin emulsion, the synthetic and structural regulation techniques are systematically studied, and the rheological properties and influencing factors of the water-borne resin are deeply explored, and the resin is further applied to the water based metal paint to prepare the automotive finish, in order to develop a water-based metal paint with independent intellectual property right. The framework of the key resin is laid. The structure of the whole paper can be divided into five parts, which are divided into five chapters. The first chapter is a systematic review of the history and development of water-based acrylic resin, the synthesis method and application, the research trend of the water based metal paint, the rheological control and the rheological control method of the water-based coatings, and put forward its own topic. In the second chapter, the second chapter mainly deals with the synthesis of acrylic resin with core and shell structure for water-based metallic paint. Using common acrylate monomers as raw material, ammonium persulfate as initiator, twelve alkyl sodium sulfate (SLS) and alkyl phenol polyoxyethylene ether (OP-10) as compound emulsifiers, the preparation of water-based metal lacquer by core shell emulsion polymerization technology The effects of reaction temperature, initiator concentration, emulsifier ratio and concentration on reaction conversion, particle size and molecular weight were systematically investigated. The results showed that the small amplitude of temperature change had little effect on the conversion rate. As the concentration of initiator increased from 0.30% to 0.62%, the transformation of the system was first increased and then decreased, and the molecular weight was increased. However, the amount and proportion of the optimum initiator concentration in the 0.39%. emulsifier have a great influence on the conversion and particle size distribution. With the addition of the negative: the increase of OP-10 in the non ionic emulsifier and the decrease of the reaction rate, the particle size of the product increases and the distribution becomes wider. The reason may be that the emulsifying ability of OP-10 is weaker than that of SLS. In the case of fixed Yin: non ionic emulsifier (mass ratio) =1:0.5, the amount of the total emulsifier increased from 1% to 2.5%, the reaction conversion first increased and then tended to be stable, and the particle size distribution of the emulsion narrowed. The optimum synthesis route was SLS: OP-10=1:0.5, the concentration of emulsifier 1.40%, and the concentration of initiator 0.39%. The reaction temperature is 76 C, the conversion rate of the system can reach 96.4%., and the resin emulsion is characterized by electron microscope, infrared, GPC, hot weight and so on. It is applied to the formulation of water based metal paint, and good aluminum powder orientation and film forming properties are obtained. The FI value is 23.04. third chapter of the developed alkali swelling core shell structure acrylic resin. The effect of the monomer composition of the polymer on the thickening property and viscoelasticity of the resin was studied systematically. The results showed that the acid monomer methylacrylic acid (MAA) was the root and main cause of the thickening of the resin, which had the greatest influence on the thickening of the resin and the regulation of the rheology. With the increase of HPMA content, the swelling ability of the resin is increasing and the viscosity and modulus of the system increase slightly. With the increase of BA content in the soft and hard monomer of the nuclear layer, the swelling ability of the resin is also strengthened, but the system modulus increases first and then decreases. It is inferred that the viscosity of the system is high when the content of BA is high. The cause of the rise and reverse is the decrease of the strength of the polymer structure. The effect of the shell and hard monomers on the viscoelasticity of the system and the nuclear layer. The fourth chapter is a thorough investigation of the preparation and thickening mechanism of the common thickening resin emulsion of the alkali and auxiliaries for water-based metallic lacquers and the thickening mechanism of the waterborne acrylic resin emulsion of alkali (organic amine, such as two methyl ethanolamine). After the solution is neutralized, the polymer chain segment swelling and thickening to achieve rheological control because of the dissociation of the carboxyl group. However, the organic amine neutralizer used in the system tends to volatilize with the prolongation of storage time or the increase of the ambient temperature, thus affecting the thixotropy of the system and even the stability of the product. The body (two vinyl benzene) core-shell structure acrylic resin emulsion, the emulsion can not thickening directly with alkali, but it can thicker and have strong thixotropy after adding a small amount of film forming auxiliary glycol butyl ether. The swelling line of the emulsion under the joint action of alkali and auxiliary agent is made with the hand segment of particle size instrument, surface tension meter, rheometer and scanning electron microscope. The interfacial properties, microstructure and rheological properties were characterized and studied in detail. The results showed that the alkali could expand the latex particles in a small margin. The additives could not be swelling particles but could change the interfacial properties of the emulsion to flocculate them. The mechanism of the common thickening of alkali and auxiliaries was the addition of the capacity of the tree fat alkali and the flocculation effect of the auxiliaries. The rheological properties of the common thickened dispersion can be regulated by the solid content, neutralization degree and the amount of auxiliaries, and the thickened dispersion is very stable. The room temperature is sealed for six months without phase separation and can be well cut. The fifth chapter is to verify the effectiveness and universality of the common thickening mechanism of the alkali and auxiliary agents. The thickening model was introduced into the common non nuclear acrylic emulsion system. Simple acrylic copolymerization emulsion was prepared by three monomers of methacrylic acid and methyl methacrylate methyl methacrylate, three monomers, which were embedded in the particles, and the emulsion was directly neutralized by alkali and could not be thickened. The study shows that the thickening of the resin is still the addition of the swelling capacity of the resin base and the flocculation effect of the additives. Further research on the rheological properties of the system shows that the thickening ability of the resin is also composed of the polymer, the amount of additives and the types of the additives. In addition, the model of the common thickening of alkali and auxiliaries was introduced into the traditional styrene acrylic emulsion system. It was found that the model was also applicable, and the model should be universality, and other water-based acrylic emulsion systems such as ethylene propylene emulsion, vinegar acrylic emulsion and other emulsion systems could be extended.

【学位授予单位】：武汉大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ630.1

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