涂层固化过程中胶乳粒子迁移的机理（Ⅱ）

Mechanism of Latex Particle Migration during Coating Consolidation (II)

关键词:  涂层固化  胶乳粒子  迁移机理  布朗运动  XPS

Key Words:coating consolidation  latex particle  migration mechanism  Brownian motion  XPS

摘要:研究了涂布纸涂层固化过程中胶乳粒子向涂层表面发生迁移的现象，对此提出了一种新的基于Einstein经典粒子扩散理论和表面效应的机理来进行解释，澄清了涂料及相关领域对粒子迁移机理的争议。以微米级高岭土、亚微米级羧基丁苯胶乳为主要原料制备涂料进行涂布，用 X射线光电子能谱仪（XPS）检测涂层表面的元素组成和含量，建立了原子数比值与胶乳用量之间的回归方程；通过该方程将不同条件下固化的涂层表面XPS检测结果转化为表面胶乳含量，定量分析了不同因素对胶乳粒子迁移程度的影响。结果表明，干燥温度升高、高温干燥时间延长、涂料初始固含量降低会促进胶乳向涂层表面迁移，而胶乳粒径增大、涂料黏度增加、基质吸收性增强会抑制其迁移，验证了新机理的合理性。

Abstract:The migration of latex particles to the coating surface during consolidation was investigated, and a new mechanism based on Einstein classical particle diffusion theory and surface trapping effect was proposed to clarify the controversy in coating and related fields. X-ray photoelectron spectroscopy (XPS) technique was used to determine the elemental composition and content at the surface of coating comprised mainly of micron sized kaolin clay and sub-micron sized styrene butadiene latex, and regression equation was established between surface atomic concentration and latex amount in the formulation. By converting the surface XPS results of coatings dried under various conditions to latex content using the above equation, the effect of various factors on the degree of latex particles migration was analyzed quantitatively for the first time. The results showed that latex migration to coating surface can be promoted by increasing drying temperature and drying time, and decreasing the initial solid content of coating colors, while impeded by raising its particle size, the substrate absorption, initial solids content and viscosity of coating colors, and therefore the new mechanism was verified.