共查询到18条相似文献,搜索用时 93 毫秒
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《涂料技术与文摘》编辑部 《涂料技术与文摘》2009,30(7):15-21
介绍了全球涂料用添加剂市场情况,着重介绍了涂料用增稠剂。对缔合型增稠剂、与水相相结合的非缔合型增稠剂、无机增稠剂、有机触变胶等类型的增稠剂分别加以阐述。 相似文献
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增加乳胶漆着色时黏度稳定性的缔合增稠剂 总被引:1,自引:0,他引:1
《涂料技术与文摘》2005,26(2):8-11
本文介绍了一种新型的采用氨基树脂的缔合增稠剂。通过在分子中引入比聚氨酯型缔合增稠剂更多的憎水部分,从而达到使用缔合增稠剂后,即使再向水性涂料中加入溶剂如二元醇或表面活性剂时,黏度也能保持稳定。 相似文献
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新型的碱溶胀缔合型增稠剂 总被引:1,自引:0,他引:1
前言 鉴于缔合型增稠剂优越的流变性,已得到了广泛的认可,并已成为大部分建筑涂料所钟爱的产品。传统使用的二种主要的增稠剂是水溶性的纤维素,特别是羟乙基纤维素(HEC)及羟丙基甲基纤维素(HPMC)和碱溶胀或可溶型乳液(总称ASE)。如同其它分子量较高的非缔合型水性聚合物一样,这些增稠剂主要是通过流体力学机理,仅能提高水相的粘度(图1)。在有分散相胶体粒子存在的情况下,即颜料及乳胶粒子,增稠和流变将进一步受到另外的非缔合机理的影响。这可称为“体积限制”(Volume restri-ction)或“减液”(depletion)絮凝。 相似文献
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增稠剂可以提高物系黏度,使物系保持均匀稳定的悬浮状态或乳浊状态,或形成凝胶。目前常用的增稠剂有纤维素及其衍生物类、聚丙烯酸及其共聚物类、非离子缔合型聚氨酯类等,对不同增稠剂特性的了解对于根据需要选择合适的增稠剂非常重要。主要以纤维素及其衍生物类、聚丙烯酸及其共聚物类、非离子缔合型聚氨酯类这三类主要的增稠剂为主,综述了乳液增稠的相关增稠机理以及研究应用技术。 相似文献
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利用二异氰酸酯和聚乙二醇在封端剂的存在下合成了一种水性聚氨酯缔合型增稠剂;考察了不同单体、封端剂以及反应工艺对产物增稠性能的影响;讨论了增稠剂的相对分子质量和相对分子质量分布与其增稠性能的关系。 相似文献
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A. J. Reuvers 《Progress in Organic Coatings》1999,35(1-4):171-181
Water-borne decorative topcoats generally show inferior leveling and open time compared to solvent-based paints. Basically, this behavior is caused by the divergent viscosity–solid content relationship for dispersions and emulsions and by the relatively high evaporation rate of water. Employment of associative thickeners may improve leveling and open time of latex paints only if they introduce a substantial amount of ‘network viscosity,' characterized by a short relaxation time and little dependence on solid content. This network viscosity enables one to formulate a paint with sufficient high-shear viscosity at a particle-packing density far below the value where low-shear viscosity starts to diverge. Addition of an associative thickener not only affects rheology, but also the interaction between latex particles: Associative HEUR thickeners may induce undesired phase separation by strong bridging between the latex particles. The influence of HEUR thickeners on latex particle interaction has been studied by turbidity measurements. The experimental results could qualitatively be interpreted very well by two-particle interaction potentials computed using the Self-Consistent-Field theory of Scheutjens and Fleer. It is demonstrated how viscosity, created by the addition of an associative thickener to a highly concentrated latex, can be split up into a polymer network viscosity and a contribution to (relative) dispersion viscosity. According to these analyses, reduction of the molecular weight of tri-block HEUR thickeners yields an increase of the favorable network viscosity and a reduction of the unfavorable dispersion viscosity. However, reduction of the molecular weight of the HEUR thickener is limited by the introduction of undesired phase separation (bridging flocculation) below a certain molecular weight. 相似文献
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通过二并氰酸酯和聚乙二醇在封端剂的存在下合成了一种水性聚氨酯缔合型增稠剂,考察了不同的单体、链封端剂以及反应的工艺条件对产物增稠性能的影响,并讨论了增稠剂相对分子质量和相对分子质量分布与其增稠性能之间的关系。 相似文献
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The chemistry of radiation curable polyurethane dispersions is outlined with an emphasis on the microstructure of the aqueous polymer dispersion and the possible interactions with associative thickeners. The steady-shear flow was studied for two model dispersions prepared from the same unsaturated polyurethane but showing significantly different particle size distributions. A hydrophobically modified ethoxylated urethane (HEUR) associative thickener with a linear structure was incorporated at different amounts to the dispersions with varying particle volume fractions. The steady-state viscosity at 25 and 10 °C was always reached quickly after instant flow rate changes so that no significant thixotropic effects were reported within the experimental timescale. Without thickener, the flow curves of the two model dispersions exhibited a Newtonian behavior except at the highest volume fractions where shear thinning became apparent. The maximum packing values determined from the Krieger–Dougherty relationship were essentially the same for the two systems. In the presence of thickener, the flow curves were characterized by a Newtonian plateau followed by a marked shear thinning region even at low particle volume fractions. This behavior typically suggests the formation of a physical network between polyurethane particles and thickener molecules partly adsorbed onto the polymer surface. The zero-shear viscosity of the two dispersions was compared with respect to: (i) particle volume fraction and (ii) particle surface area at different HEUR concentrations. At a given volume fraction, the particle size affects the viscosity of thickened models. As a corollary, a relationship is found between the particles size and the level of thickener required to reach a target viscosity. This study offers practically relevant data in terms of application conditions and provides a better insight into the thickening protocol. 相似文献
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Gijsbert Kroon 《Progress in Organic Coatings》1993,22(1-4):245-260
The associative behavior of hydrophobically modified hydroxyethyl cellulose (HMHEC) in polymer dispersions has been determined as a function of the composition of both the associative thickener (AT) and the latex. How changes in interaction between HMHEC and the latex influence the rheology of the latex thickener systems is discussed. Adsorption of HMHECs onto an acrylic emulsion strongly depends on the hydrophobe type and degree of substitution, as well as on the molecular weight of the associative thickener. The degree of latex adsorption is influenced dramatically by the stabilization system utilized, that is choice and level of surfactant and carboxylic acid content, in addition to the composition of the monomer mix. Rheological measurements demonstrate that HMHECs of specific composition can provide gloss emulsion paints with a balance of rheological properties, combining excellent levelling with sag resistance. 相似文献