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    • 4. 发明授权
    • Fabrication including sol-gel processing
    • 制作包括溶胶 - 凝胶加工
    • US5944866A
    • 1999-08-31
    • US89859
    • 1998-06-03
    • You-Lung ChenSanjay PatelJorge Luis Valdes
    • You-Lung ChenSanjay PatelJorge Luis Valdes
    • C03B8/02C03B20/00C03B37/012C03C1/00C03B37/016
    • C03C1/006Y10S65/901
    • The invention provides an alternative to conventional sol-gel methods that utilize undesirably high amounts of a stabilizing agent such as TMAH and a gelling agent such as methyl formate. The method involves the steps of (a) providing a colloidal silica dispersion containing a stabilizing/gelling agent, where only a portion of the molecules of the agent ionize, and (b) subsequently adding to the silica dispersion a pH-reducing additive. The stabilizing/gelling agent has a dual function. The agent, e.g., an amine, initially acts as a stabilizer in the silica dispersion in that a portion of its molecules ionize, while an appreciable amount of the agent remains non-ionized. The agent later transforms in situ to a gelling agent upon addition of a pH-reducing additive. Specifically, as the pH-reducing additive lowers the pH to values at or around the pK.sub.a of the stabilizing/gelling agent, more of the agent's molecules are ionized, these cations contributing to charge neutralization, and thus gellation, of the colloidal silica particles.
    • 本发明提供了常规溶胶 - 凝胶方法的替代方案,其使用不希望的大量稳定剂如TMAH和胶凝剂如甲酸甲酯。 该方法包括以下步骤:(a)提供含有稳定/胶凝剂的胶态二氧化硅分散体,其中只有一部分试剂的分子离子化,和(b)随后向二氧化硅分散体中加入pH降低添加剂。 稳定剂/胶凝剂具有双重功能。 该试剂,例如胺最初充当二氧化硅分散体中的稳定剂,因为其一部分分子离子化,而相当量的试剂保持非离子化。 该添加剂随后在添加pH降低添加剂时原位转化为胶凝剂。 具体地说,随着pH值降低添加剂将pH降低至稳定/胶凝剂的pKa值或周围值,离子化剂的分子越多,这些阳离子有助于胶体二氧化硅颗粒的电荷中和,从而凝胶化。