铝银浆的特性

2020-04-07503

  铝银浆的特性

  溶剂的挥发会在湿膜内部引起强烈的涡旋,但是如果溶剂挥发太慢,则会形成所谓的“伯纳德涡旋”,这会阻碍铝银浆的平行取向并显得混浊。可以使用能促进溶剂快速挥发的树脂(例如乙酸丁酸纤维素CAB),也可以使用一些可以固定颜料颗粒的添加剂。据文献报道,蜡分散体可以起到“间隔效应”的作用,表面活性剂具有类似的功能。但是效果要使用前进行测试。

  超薄金属颜料对高剪切力非常敏感。机械剪切将导致颗粒变形或形成许多细颗粒,这将降低光学效果。在严重的情况下,剪切会产生大量未保护的金属表面,它们的活性会导致与涂层系统发生化学反应。因此,有必要注意金属颜料的机械性能,特别是当颜料分散时以及在要求严格的泵送系统和循环管线中使用金属涂料时。

  铝的化学性质很大地限制了系统中树脂和溶剂的选择(表3)。

  Characteristics of Aluminum paste

  The evaporating solvent creates powerful turbulences within the wet film, however, and if evaporation is too slow these hinder the orientation of the aluminium paste through the formation of so-called Benard cells (clouding).It is a help here to use binding agents which release the solvents quickly (e.g. cellulose acetobutyrate) or to include additives which fix the bronze particles. Attention is drawn in the relevant litera­ture to the positive effect of wax dispersions as "distance keepers"; surface active substances are also available for this purpose, but their effect in the binding agent must be tested first.

  Extremely thin metallic pigments are sensitive to high mechanical shear forces,The consequences of mechanical shear stress caused by deformation of the particles, the loss of optical properties by creating very fine particles could be the creation of specs, and in the worst case chemical reactions caused by the creation of unprotected metal surfaces and thus the chemical activation of the metallic pigments which can cause interaction with the paint system.Attention should be paid to the mechanical properties of the metallic pigments especially during dispersion but also when special effect metallic paints are being processed in critical pump systems or circulation lines.

  The chemical properties of aluminium, severely limit the choice of binders and solvents (Table 3).

  化学特性 / Chemical properties

  表3/Table 3

介质/Behaviour towards

铝/Aluminium

酸性介质/   Acid media

发气、发灰 /   Gas formation, greying

碱性介质 /   Alkaline media

发气 /   Gas formation

卤素/Halogens

发气 /   Gas formation



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