Condensation vs Addition-cure Silicone Chemistry
缩合型与加成型硅胶的化学机理对比
标签：硅胶化学, 交联机理, 铂金催化, 收缩率
两类 RTV 硅胶的机理决定其适用性：缩合型（脱醇/脱酮肟型）以锡催化室温交联，放出小分子醇，线性收缩 0.3–0.7%、有气味、对石膏母模附着性好，但催化剂残留会抑制后续树脂固化；加成型（铂金催化）通过硅氢加成固化，无副产物，收缩小于 0.1%、无毒无味、有食品接触级，但痕量的硫、磷、胺（乳胶手套、油泥、某些 3D 打印树脂）即可令铂金催化剂中毒不固化。选型口诀：长期生产与精细纹理选加成型，一次性低成本翻模选缩合型。
The chemistry decides the job: condensation-cure RTV (alcohol/oxime types) is tin-catalysed at room temperature, releases small alcohols, shrinks 0.3–0.7%, smells, and grips plaster masters well—but catalyst residues inhibit later resin casts. Addition-cure (platinum) crosslinks by hydrosilylation with no by-product: shrinkage under 0.1%, odourless, with food-contact grades—yet traces of sulphur, phosphorus or amines (latex gloves, plasticine, some printed resins) poison the platinum and stop the cure. Rule of thumb: platinum for production and fine texture; condensation for cheap one-off moulds.