SEED SEMICONTINUOUS EMULSION MULTI-COPOLYMERIZATION OF (METH) ACRYLATES WITH HIGH-SOLID CONTENT: EFFECT OF THE OPERATION CONDITIONS

The seeded semicontinuous emulsion multi-copolymerization of butyl acrylate (BA), 2-ethylhexyl acrylate (2EHA), methyl methacrylate (MMA), 2-hydroxyl propyl acrylate (HOPA) and acrylic acid (AA) was used to prepare the acrylic latexes with high-solid content. The effects of monomer emulsion feed rates (R(a)) and (R/E)(E) values, the ratio of emulsifier amount between the initial charge (R) and the addition monomer emulsion (E), on the polymerization reaction features, the viscosities, surface tensions,particle sizes and particle sizes distributions of latexes, T-g and the insoluble fractions of films, the 180 degrees peel strength, tack and holding power of pressure-sensitive adhesive (PSA) tapes, prepared from the latexes, were studied. Experimental study shows that the grafting and crosslinking fraction in the PSA tapes must be controlled within a suitable range to keep the balance of the 180 degrees peel strength, tack and holding power.

STUDY ON THE FORMATION MECHANISM OF MONODISPERSE PARTICLES IN THE EMULSIFIER-FREE EMULSION POLYMEAIZATION OF METHYL METHACRYLATE AND BUTYL ACRYLATE

The formation mechanism of monodisperse polymer latex particles in the emulsifier-free emulsion polymerizationof methyl methacrylate and butyl acrylate with potassium persulfate as initiator was investigated. A multi-step formationmechanism for the monodisperse polymer particles was proposed. The nucleation mechanism is considered to be thecoagulation of the precursor particles by homogeneous nucleation when the primary particles reach a critical size with highsurface charge density and sufficient stability. It had been proved by a special experiment that the early latex particles formedby the coagulation were stable. The primary particles grow by absorbing monomers and radicals in the polymerization systemand then become colloidally unstable again due to the understandable decrease of particle surface charge density, which leadsto the aggregation of the growing particles and the formation of larger latex pedicles therefrom. Aner the nucleation period,the preferential aggregation of the smaller particles in the propagation process leads to the change of the particles towards auniform size and narrower particle size distribution. The coexistence and competition of homogeneous nucleation,coagulation, propagation and aggregation result in the increase of the polydispersity index (U = D_(43)/D_(10)) in the first Stage,then its decrease in the later stage because of the competition of propagation and aggregation, and the gradual formation ofthe monodisperse particles.

Synthesis and properties of acrylate latex modified by vinyl alkoxy siloxane

Acrylate latex modified by vinyl triisopropoxy silane (C-1706) was synthesized by seeded emulsion polymerization with anionic emulsifier sodium dodecyl sulphonate(SDS) and nonionic emulsifier OP-10 as the multiple emulsifiers at (78±2) ℃. The effects of different factors, such as the emulsifier, C-1706 monomer and its feeding manner on the properties of acrylate latex modified by C-1706 were investigated. The particle size distribution and the structure, the configuration, the weather durability and stain resistance of copolymer latex were characterized by particle size analyzer, Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope(TEM), scanning electron microscope(SEM) and ultraviolet aging instrument respectively. The results show that SDS to OP-10 as multiple emulsifiers can lead to coordinated efficiency, the optimal emulsifier dosage is 2.4%?3.2%(mass fraction), and the mass ratio of SDS to OP-10 is 1?1? 1?2. The seeded emulsion polymerization can effectively introduce a organic-siloxane bonding in a macromolecule inter polymer, and the obtained acrylate latex modified by organic-siloxane possesses narrow distribution of particle size with mean diameter of 51.8?76.6 nm and has the excellent properties in weather durability and stain-resistance especially.

Preparation of Styrene-acrylate Latex Used in Ultralow VOC Building Internal Wall Coating

Styrene-acrylate latex with high glass transition temperature （T）, low minimum film forming temperature（MFT） and good stability was prepared via core-shell emulsion polymerization. With semicontinuous process, high conversion rate of monomer and low gel rate were achieved. The weight ratio of core monomer to shell monomer was approximately 1.35. It is found that many factors such as emulsifiers, initiators, reaction temperature, pH value and polymerization technology have influences on the permormance of styrene-acrylate latex. The prepared latex was characterized by TEM and FTIR. The obtained latex with T of 20.57 ℃, MFT or5.0 ℃, and good stability, had good stability of film forming.

无氟拒水剂成膜表面形貌及其拒水性能研究

为考察无氟拒水乳液的成膜形貌对拒水性能的影响,将细乳液聚合得到的聚丙烯酸十八酯-丙烯酸丁酯[P(SA-BA)]胶乳分别与四种粒径的聚丙烯酸十八酯/γ-甲基丙烯酰氧基丙基三甲氧基硅烷[P(SA-A174)]胶乳按比例共混后,采用涂覆和浸轧两种工艺整理玻璃片和面料,以SEM和AFM考察了整理得到的两种基材表面形貌,并考察了对拒水性的影响。结果表明:P(SA-BA)和P(SA-A174)分别具有成膜和保型能力,二者复合而成的胶乳可形成具有纳米“指突”形貌的拒水膜,使整理基材的拒水性能明显提升。随着P (SA-A174)粒径的增大和用量的提高,涂层整理膜的“指突”高度和面密度同时增加,而浸轧整理时,仅“指突”高度增加,面密度和拒水性能变化不大。之后,通过降低浸轧液pH值,胶乳对织物亲和力以及吸附效率增强,浸轧整理织物拒水性能明显提升。

Effect of cationic monomer on properties of fluorinated acrylate latex

Cationic fluorinated acrylate latex was prepared via semi-continuous emulsion copolymerization of cationic monomer and other monomers. The resultant latex and its film were characterized with dynamic light scattering detector and contact angle meter. Influences of amount of DMDAAC on the properties of resultant latex and its film were investigated in detail. Results show that the particle size of the latex has the minimum value knd the zeta potential of the latex is increased when the amount of DMDAAC is increased. In addition, the particle size of the latex is unimodal distribution when the amount of DMDAAC is not more than 2.5%. However, the particle size of the latex is bimodal distribution when the amount of DMDAAC is more than 2.5%. The contact angle is varied slightly with the increase of amount of DMDAAC when it is not more than 2.5%. Nevertheless, the contact angle is decreased with the increase of the amount of DMDAAC when it is more than 2.5%.

有机硅改性丙烯酸酯共聚乳液合成方法及胶膜性能的研究

用一次投料法、单体乳液滴加法和引发剂滴加法合成了有机硅改性丙烯酸酯共聚乳液。聚合过程、胶粒形态及乳液稳定性的观测结果表明：单体乳液滴加法是合成该类乳液的最佳方法。研究了单体乳液滴加法中有机硅含量与聚合反应及胶膜性能的关系。结果表明：有机硅含量在１５％以下时，聚合反应可以顺利进行。胶膜性能不仅依赖于聚合时有机硅单体的总量，而且还依赖于有机硅单体中活性硅氧烷所占的比例。

印刷纸张用苯丙水性上光油的研制

采用苯乙烯、甲基丙烯酸甲酯、丙烯酸丁酯等为单体,吸取微乳液聚合和无皂乳液聚合的一些特点,以非预乳化的半连续加料方式加料,合成出苯丙共聚物乳液。研究了PH调节剂、后续单体滴加时间以及保温反应时间等工艺条件对乳液及乳胶膜性能的影响。结果表明,所制得的乳液的单体转化率、乳液固含量和凝胶率分别为95.31%、42.66%和0.41%;乳胶膜的光泽度达到94.8%,吸水率为19.2%,乳胶膜的硬度、柔韧性和附着力俱佳。

丙烯酸甲酯与醋酸乙烯酯的种子乳液聚合

以过硫酸铵（ＡＰＳ） 为引发剂，合成了粒径分布较均匀的聚醋酸乙烯酯种子乳液（ＰＶＡｃ） ，然后以丙烯酸甲酯（ ＭＡ） 为第二单体和以油溶性偶氮二异丁腈（ＡＩＢＡ） 为引发剂，分别进行不溶胀与溶胀条件下的无皂种子乳液聚合，并用透射电子显微镜（ＴＥＭ） 表征了胶粒形态．表明在不溶胀条件下，胶粒形态随ＰＶＡｃ／ ＭＡ 重量比的不同而变化，当ＰＶＡｃ／ ＭＡ 为１／２ 时，形成以ＰＭＡ 为核，ＰＶＡｃ 为壳的胶粒．在溶胀条件下则得到类似互穿网络型乳胶粒．

核／壳型聚硅氧烷丙烯酸酯复合乳液的制备

采用种子乳液聚合的方法制备了具有核／壳结构的聚硅氧烷丙烯酸酯复合乳液，考察了乳化剂、单体的加入方式及配比对产生乳液粒子的影响。结果表明，乳化剂在核阶段和壳阶段的单体聚合中都起着很重要的作用，当乳化剂分子在乳液粒子上的覆盖率低于４０％时，可制得较理想的核／壳型复合乳液．

化学交联及物理缔合对聚丙烯酸增稠剂的作用

采用反相乳液聚合法合成聚丙烯酸类增稠剂，比较了交联型单体及疏水型共聚单体对聚合产物在水中粘度及耐电解质的影响。结果指出，一定量的交联型单体及疏水型长链单体都能明显增加粘度。疏水单体中甲基丙烯酸十六酯（ＨＭ）的影响大于甲基丙烯酸十二酯（ＬＭ）的影响。含疏水型长链单体的缔合型交联增稠剂比非缔合型交联增稠剂的性能更优良。此外，还研究了两种类型的聚合物浓度及反相剂对粘度的影响以及用扫描电镜（ＳＥＭ）观察了聚合物胶乳的粒子形态。

涂料用可交联聚丙烯酸酯乳液的研究进展

对涂料用可交联丙烯酸乳液的制备方法、组成、结构与乳液及涂膜性能的相互关系和各种乳液体系的交联机理作了较详细的综述。

水性涂料用阳离子聚丙烯酸酯乳液的合成

采用种子预乳化半连续法,合成了固含量高的阳离子型聚丙烯酸酯乳液。考察了在乳液聚合中反应性乳化剂、引发剂种类及功能单体含量对乳液聚合稳定性及乳液性能的影响。结果表明:在乳液聚合体系中,功能单体HEA含量为1%最佳;合理的反应性乳化剂用量及加入方式可使乳液固含量达到41%;选用AIBN与BPO复配的引发剂制备的乳液性能良好。

环氧改性丙烯酸树脂复合乳胶的合成及其性能研究

利用乳胶胶束的包裹作用,在水相中将双酚A环氧二丙烯酸酯与丙烯酸酯单体混合物束缚其内。通过乳液聚合实现两相在水相体系中的有效共聚,得到环氧改性丙烯酸树脂的复合乳胶。通过傅里叶变换红外光谱(FT-IR)、热重分析(TGA)、粒径分析(DLS)、扫描电镜(SEM)、透射电镜(TEM)等对所制备的复合乳胶进行了表征,并测试了涂膜的力学性能、极化曲线。结果表明:乳胶粒子呈均匀的球形;当双酚A环氧二丙烯酸酯用量为整体复合树脂质量的5%时,涂膜的力学性能、热稳定性和耐腐蚀性均较优异,可较广泛应用于金属防护等领域。

非离子型乳化剂对聚丙烯酸酯乳液性能的影响

在非离子型表面活性剂用量和聚氧乙烯(EO)链长数目变化的条件下制备了纯丙烯酸酯聚合物乳液(简称纯丙乳液),考查了非离子型乳化剂用量和EO链长对乳液聚合稳定性及乳液冻融稳定性,Ca2+稳定性,玻璃化温度(Tg),粒径和黏度的影响.实验结果表明,非离子乳化剂用量和EO链长的增加,有助于乳液聚合反应的平稳进行,得到的乳液粒径较小,黏度较大,Tg较低,乳液的冻融稳定性和Ca2+稳定性显著提高.

有机硅／纳米TiO2改性丙烯酸酯乳胶涂料的研究

采用溶胶-凝胶法制备二氧化钛(TiO_2)溶胶,并用含有可聚合基团的硅烷偶联剂(KH-570)对其进行接枝改性,制备可聚合的有机硅改性纳米TiO_2溶胶,然后通过核壳乳液聚合法,制备有机硅/纳米TiO_2改性丙烯酸酯乳液,并配制乳胶涂料。研究了改性纳米TiO_2溶胶、乳化剂和引发剂的用量对乳液及乳胶膜性能的影响。结果表明:有机硅/纳米TiO_2改性乳胶膜玻璃化转变温度和热稳定性有所提高,乳胶涂料的综合性能也有所改善。

聚合条件对聚丙烯酸胶乳增稠性能的影响

用反相乳液聚合方法合成了对水增稠性能好的交联聚丙烯酸胶乳。研究了交联剂的用量、引发剂的种类和用量、水相的ｐＨ值、共聚单体内烯酰胺（ＡＭ）的用量、单体浓度以及聚合温度等因素对胶乳增稠性能的影响。同时指出，通过控制水相的ｐＨ值和引入非离子型亲水性单体如ＡＭ的方法，可提高聚丙烯酸胶乳增稠剂的耐电解质能力。

基于磷酸酯乳化剂的丙烯酸乳胶及其漆膜性能影响研究

采用磷酸酯类乳化剂,通过乳液聚合方式制备了新型水性金属防腐乳胶,研究了乳化剂种类、硬单体比例以及体系玻璃化转变温度的变化对丙烯酸乳胶以及漆膜性能的影响。对制得的乳胶尺寸与分散性进行了表征;研究了漆膜的力学性能及耐腐蚀性等性能。结果表明:使用磷酸酯乳化剂,由于在体系中引入了磷酸根离子,其可与金属离子产生络合作用,能有效提高丙烯酸酯乳胶的耐腐蚀性:同时以苯乙烯作为硬单体主体,设定适当的玻璃化转变温度,可使最终的丙烯酸乳胶体系具有良好的力学性能及耐腐蚀性。

聚氨酯-聚丙烯酸树脂乳液聚合特征

讨论了在聚氨酯水分散体中进行丙烯酸酯乳液共聚合的一些特征。研究表明：聚氨酯水分散体起着种子乳液的作用，所得聚氨酯－聚丙烯酸酯乳液具备有核壳型结构特征，综合性能显著提高。

苯丙乳液的制备及其性能影响因素研究

以苯乙烯、丙烯酸丁酯为主单体,丙烯酸(AA)为功能单体,SDS/OP-10为复合乳化剂,过硫酸铵为引发剂,采用单体预乳化、半连续种子乳液聚合工艺,制备出性能优异的苯丙乳液。采用FT-IR、DSC、GPC、Nano-ZS90等对聚合物乳液进行了表征,系统研究了单体配比、复合乳化剂、引发剂用量、聚合温度等因素对乳液成膜性、耐水性、稳定性等常规性能的影响。结果表明,乳胶粒粒径受复合乳化剂种类及用量的影响较大,同时也与引发剂用量有关;单体配比是乳液玻璃化温度(Tg)的关键影响因素。