苯丙乳液的最低成膜温度及其影响因素分析

简单介绍聚合物乳液的最低成膜温度及其测定方法，详细讨论了聚合物乳液组成、聚合物极性、单体亲水性、聚合物乳胶粒子性能、乳化剂、增塑剂及成膜助剂等因素对聚合物乳液最低成膜温度的影响。     

核-壳苯丙微乳液最低成膜温度的研究

通过核-壳微乳液聚合技术合成了具有较高玻璃化转变温度(Tg)的苯丙微乳液,研究了核-壳单体用量比、壳单体组成、交联剂、聚合物极性对乳液最低成膜温度(MFT)的影响;同时比较了三种成膜助剂对乳液MFT的作用。研究发现,成膜温度随核-壳比的增大而上升;交联剂羟甲基丙烯酰胺(NMA)能有效地降低成膜温度;醇酯—12是一种良好的成膜助剂,同一成膜助剂对极性不同的乳胶粒子MFT的降低效果明显不同。     

有机硅-苯丙乳液的最低成膜温度

清华大学的杜奕等人以有机硅单体、丙烯酸丁酯、甲基丙烯酸、苯乙烯等为原料,采用半连续法制备了稳定的有机硅-苯丙乳液,研究了软硬单体配比和有机硅单体含量对共聚物玻璃化温度(Tg)及乳液最低成膜温度(TMF)的影响;并选用3种成膜助剂分别考察了成膜助剂的种类、用量对乳液TMF的     

低温高湿水痕恢复苯丙真石漆乳液的研制

分析了真石漆配方,考察了成膜助剂、防冻剂、砂子配比对真石漆水痕恢复的影响,发现成膜助剂和砂子配比对水痕恢复性能影响较大,即通过降低乳液的成膜温度可以改善水痕恢复性能,但是成膜温度过低会造成黏结强度不达标,以及冻融不太稳。通过核壳工艺、亲水单体、交联单体的配合使用制备出了水痕恢复性能好的苯丙真石漆乳液,能够达到轻痕的效果。     

有机硅-苯丙乳液最低成膜温度的研究

采用半连续法制备了稳定的有机硅-苯丙乳液，研究了软硬单体配比和有机硅单体含量对共聚物玻璃化转变温度(Tg)和乳液最低成膜温度(MFT)的影响：并选用3种成膜助剂(TXL、DPD和二乙二醇二乙醚)分别考察了成膜助剂的种类和用量对乳液产品MFT的影响。结果表明，共聚物T和乳液的MFT呈较好的线性关系，该乳液体系MFT/Tg约为0．97；乳液产品的MFT随成膜助剂用量的增加而大幅降低，其中二乙二醇二乙醚的效果最好。     

含氟丙烯酸酯乳液高疏水性与低氟含量的平衡探索

为了研究含氟丙烯酸酯乳液涂膜的疏水性与氟含量的平衡关系,以甲基丙烯酸十二氟庚酯(DFHM)为含氟单体,双丙酮丙烯酰胺(DAAM)和己二酸二酰肼(ADH)为交联单体,采用半连续核壳乳液聚合的方法合成了一系列自交联含氟丙烯酸酯共聚物乳液。研究表明:含氟单体含量为12%(即氟含量为6.84%,均以聚合单体的总质量计,下同)时,含氟基团在涂膜表面可以达到饱和,乳液固含量可达38.2%;再添加4%交联单体,涂膜的水接触角为116.6°。当含氟单体含量降为4%(氟含量2.28%)时,通过提高成膜温度或添加成膜助剂,也可使涂膜表面的水接触角达到104.2°,具有较好的疏水性能。     

乳液的最低成膜温度及其影响因素

乳胶漆的成膜行为可以通过最低成膜温度（MFT）进行表征。介绍了MFT的测定方法。详细讨论了玻璃化温度、乳液粒径、成膜助剂、干燥条件及贮存时间等因素对MFT的影响。     

降低苯丙乳液最低成膜温度的途径

对如何降低苯丙乳液的最低成膜温度（MFT）的途径进行了总结。通过改进聚合方式,调整玻璃化温度,使用增塑剂、防冻剂、成膜助剂,均可降低苯丙乳液的MFT。     

不同交联体系对丙烯酸树脂木器涂料用乳液涂膜性能的影响

采用半连续种子乳液聚合方法，以三羟甲基丙烷三丙烯酸酯（TMPTA）、N-羟甲基丙烯酰胺（NMA）、丙烯酸锌（ZA）、双丙酮丙烯酰胺（DAAM）和己二酰肼（ADH）为交联单体，合成了具有核壳结构的交联型丙烯酸树脂乳液，并借助差示扫描量热仪（DSC）、最低成膜温度（MFT）仪等测试手段考察了4种交联体系对丙烯酸树脂乳液涂膜基本性能的影响。结果表明：在乳液体系中通过添加具有交联作用的功能单体，对硬核软壳结构的丙烯酸树脂乳液粒子中硬核层进行适当的交联，可大幅度地提高乳液涂膜的硬度，同时又可以保证乳液的低温成膜性，对制备水性丙烯酸树脂木器涂料有指导意义。     

工业用水性丙烯酸面漆的制备

采用乳液聚合方法制备水性丙烯酸乳液,以该丙烯酸乳液为成膜物质制备水性丙烯酸面漆,其各项性能指标可以达到H G/T 4 7 5 8—2 0 1 4中II型水性丙烯酸树脂涂料标准要求。同时研究了乳液玻璃化温度、成膜助剂用量和配比及其他水性助剂对涂膜性能的影响。     

Self film‐forming and opaque hollow latexes fabricated via seeded emulsion polymerization followed by alkali post‐treatment

In order to obtain novel hollow latexes with both opaque and self film‐forming properties, the four‐layer core/shell latex particles—sequentially consisting of a high carboxyl‐containing soft core, a transition layer, a rigid supporting layer, and an outermost film‐forming layer—are first designed and prepared by emulsion polymerization, and then treated with alkali to fabricate self film‐forming hollow latexes. On the basis of the previous research on the three‐layer core/shell latex, influences of the composition and thickness of the film‐forming layer on the properties and morphologies of the four‐layer core/shell and the final hollow latexes are investigated. Results show that under optimized conditions with butyl acrylate/styrene (BA/St) mass ratio of 2/1, divinyl benzene (DVB) content of 1 wt %, and core/film‐forming layer mass ratio of 1/6 in the film‐forming layer preparation, the final hollow latex particles exhibit best morphology considering both light scattering efficiency and film‐forming capability at room temperature. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42541.     

核壳型聚丙烯酸酯乳液的耐水性能研究

采用种子乳液二阶段聚合法,制备了经丙烯酸(AA)/丙烯酰胺(AM)交联、具有核壳结构的甲基丙烯酸甲酯(MMA)/丙烯酸丁酯(BA)/丙烯腈(AN)复合乳液,研究了核壳软硬单体比、AN及壳层中交联单体AM含量对乳胶膜吸水率的影响。结果表明:乳胶膜吸水率主要受壳层软硬单体比例的影响,软硬单体比值越小,乳胶膜的吸水率越低;丙烯酸/丙烯酰胺复合交联剂对乳胶膜吸水率的影响不明显;功能单体丙烯腈可明显降低乳胶膜的吸水率,乳胶膜吸水率随丙烯腈含量的增加而逐渐降低,最低达到9.40%。     

Cationic latex interaction with pulp fibers. II. Modification of sheet properties by styrene butadiene latex with quaternized amino groups

Unbeaten kraft fibers covered with experimental cationic latexes were formed into sheets in which direct fiber-fiber bonds are replaced by polymeric bonds. The effect on sheet properties—breaking length, elongation at break, folding endurance, opacity, and light scattering—was evaluated as a function of latex composition. The composition was altered by either the ratios of styrene to butadiene in the polymer or by mixing soft film-forming and hard nonfilming latex. It is shown that, regardless of latex composition and mechanical properties of the polymeric film, all the latexes can modify the sheet properties to a similar extent, providing that the sheets are heated above the polymer's glass transition temperature. An improvement of tensile strength is accompanied by increased elongation. As a probable mechanism of reinforcement, it is suggested that the polymer acts as a filler of the fiber's surface irregularities, thus providing a larger contact area between fibers and an improved stress transfer between them.     

Analytical aspects and film properties of two-pack acetoacetate functional latexes

In theory crosslinking of binders during or after film formation will result in an improvement of the physical and mechanical properties of the final paint film. Our investigation has been focused on the reaction of an acetoacetate moiety with a multifunctional amine in a latex binder system. Various aspects of two-pack acetoacetate functional latexes have been investigated. Firstly model latexes have been prepared and characterized in terms of partition of functional groups and binder material over the continuous and organic phases. It has been shown that incorporation of the acetoacetate functional monomers in the latex is successful and that the protection against hydrolysis is adequate. Secondly the reactivity with a multifunctional amine compound has been studied. The decline of the number of reactive groups has been associated with the film forming capacity and the influences on the film properties. Reaction of the components starts just after mixing, resulting in alternation of the particles and consequently influencing the film forming process negatively.     

Mechanistic considerations of particle size effects on film properties of hard/soft latex blends

Blends of hard (T_g ∼ 60°C) and soft (T_g ∼ 0°C) latexes were studied as a function of particle size ratio (R_soft/R_hard) and blend ratio (mass soft phase/mass hard phase). Addition of hard phase latex to the soft film forming latex significantly improved block resistance, even at blend ratios as low as 70/30. Film properties were not sacrificed, except at high concentrations of the hard phase (50/50). For a given blend ratio, the particle size ratio had a dramatic effect on the block resistance. For a 70/30 blend ratio, the block resistance of a blend with R_soft/R_hard=4.0 was equivalent to that of a control latex having the same overall composition, but with a minimum film temperature 20°C higher than the blend. The phenomenon can be explained in terms of the bulk and surface contributions to adhesion. The hard phase increases the elastic modulus (G’) of the film. The magnitude of G’ was found to increase with increasing R_soft/R_hard, an effect that is consistent with percolation theory. The effect of particle size ratio on the surface contribution to adhesion can be explained by particle packing. Visual models indicate that a high apparent surface concentration of hard particles would be expected for a large value of R_soft/R_hard, given ideal packing conditions. This effect was confirmed by scanning electron microscopy. Presented at the 74th Annual Meeting of the Federation of Societies for Coatings Technology, on October 25, 1996, in Chicago, IL. Emulsion Polymers Research, 1604 Building, Midland, MI 48674.     

Role of particle size on latex deformation during film formation

The ability of latex particles to deform and coalesce to form an integral film upon drying is an important property in many latex coating applications. Many theories have been proposed to account for the origin of the deformation forces. The capillary forces which depend inversely on particle size have been accepted as important for latex deformation and film formation. The minimum film forming temperature (MFFT) has been found to be a function of the particle size of latexes and has been used as evidence that the capillary forces are responsible for film formation. In this study, the deforming force at MFFT has been determined from the moduli of water-equilibrated latex polymers. No particle size dependence was observed. The magnitude of the deforming forces was at least an order of magnitude lower than that predicted by the capillary force theory. Electron microscopy of film formed below the MFFT, a condition that corresponds to early stage film formation, showed significant deformation, indicating that at the beginning of film formation, forces of magnitude predicted by the capillary force theory are present. However, the magnitude of the forces decreases rapidly as film formation progresses. The MFFT particle size dependency can be explained by the difference in the degree of water plasticization. Evidence that latexes of different particle size were plasticized by water to different extents was determined from the T_gs of the latex emulsions. Presented at the 76th Annual Meeting of the Federation of Societies for Coalings Technology, on October 15, 1998, in New Orleans, LA. Emusion Polymers Research 1604 Building, Midland, MI 48674.     

Characterization of Molecular Structure of Emulsion Acrylic Microgels: Exploring the Impact of Molar Mass on Coating Properties of Self-Cross-Linkable Latexes

Self-cross-linkable latexes of core–shell microgel particles were synthesized by the emulsion polymerization of acrylic monomers. The molar mass of copolymers forming the shell layer was gradually reduced by isooctyl 3-mercaptopropionate included in the synthesis of the shell layers. The molar mass distribution of latex particles was determined using size exclusion chromatography and asymmetric flow field-flow fractionation, respectively, both separation methods being coupled with a multiangle light scattering detector. The results confirmed theoretical predictions and described empirically the effects of molar mass of the shell layer copolymer on decreasing the minimum film-forming temperature and influencing the end-use properties of coatings.     

Effects of core-shell latex morphology on film forming behavior

A series of core-and-shell latex particles were made from methyl methacrylate/butyl acrylate copolymers. All latexes were almost monodisperse in particle size. The polymer hardness was varied by changing the methyl methacrylate/butyl acrylate ratio between the limits of 40/60 and 60/40 parts by weight. The minimum film temperatures(MFTs) of these particles were expected to vary with core and shell characteristics in the following order: soft/hard > medium/medium > hard/soft. In fact, this order was observed only if the shell thickness was greater than a certain minimum value that depends on the diameter of the core polymer. Thinner, softer shells on harder cores may require higher drying temperatures than thicker shells with the same composition because the former are required to deform more to produce void-free films.     

Investigation on the film surface and bulk properties of fluorine and silicon contained polyacrylate

A series of fluorine and silicon acrylic latexes have been prepared from acrylic monomers, 2,2,3,4,4,4-hexafluorobutyl acrylate (HFBA) and vinyltriethoxysilane (VTES) via emulsion polymerization. Morphology and particle size distribution were evaluated by transmission electron microscopy (TEM) and dynamic light scattering (DLS) methods. Surface properties of latex films were investigated in terms of ATR-FTIR spectrometry, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and water resistance measurement. It is indicated that fluorine content at the surface of fluorosilicone acrylic film decreased as the film forming temperature was increased. A high temperature favored silicon condensation at the film surface, which limited migration ability of fluorine chains. Fluorine segment contributed to surface hydrophobicity while silicon component was beneficial to improve water repellency of the film bulk. Silicon containing particles were more difficult to coalesce than fluorine acrylic particles due to the rigid crosslinked network derived from silanol crosslinking.     

聚硅氧烷/聚丙烯酸酯共聚乳液的合成与表征

合成了含氢聚甲基硅氧烷／聚丙烯酸酯共聚乳液。研究了聚合工艺，配组成及操作方式对聚合稳定性，动力学，乳液的粒径分布和产物性能的影响。采用部分预乳化单体滴加法（工艺A）的部分纯单体滴加法（工艺B）两种工艺，聚硅氧烷采用高速预乳化滴加进料方式。用COULTER LS粒径仪和Nicolet傅立叶变换红外光谱仪分别测定共取乳液的粒径分布和产物的结构。研究结果表明，采用A，B两种工艺均能得到平均粒径为0.101-0.103μm的单峰窄分布共聚乳液，并能有效地将含氢聚硅氧烷引入了到共取物大分子中。含氢聚硅氧烷的引入量为3％（质量）时，共聚物涂膜具有柔软，滑爽和强度高等优点。