Spray-polymerization

SPP工艺喷涂的目的是评估流体特性、喷涂参数和合成粉末的性能之间的相互依赖关系。喷雾聚合过程合成了一种聚合物固体。从单体合成聚合物的过程已经在喷嘴内开始，并在雾化后的液滴内继续进行。固体是由于反应过程以及载体溶剂的干燥而形成的。在一步法工艺中，工艺策略将聚合物的合成与颗粒性质的设计结合在一起，这通常需要至少两个独立的步骤。喷雾聚合被认为允许合成尺寸在5-100微米范围内的具有特定颗粒特性的聚合物颗粒。这里的一个特殊技术挑战是聚合物的综合交联性。目前的技术水平只有有限的选择来生产尺寸在1-50微米范围内的特定聚合物粒子。乳液聚合和悬浮聚合导致了致密的球形粒子。由于聚合物材料的弹性性质，自顶向下的干法精细研磨在达到约50微米以下的颗粒尺寸方面存在严重问题。一项专利审查显示了喷雾聚合的原理证明，但没有与工艺设计相关的定量数据。聚合反应和干燥过程的联合动力学是实验室和中试工作的重点，它与反应的理论描述是一致的。该技术的实现还需要开发一套专门的技术组件来控制反应的起始阶段。分析流变仪中聚合反应的实验室规模表征有力地支持了这些组分的布局，提供了反应进度和粘度的关系。后者是保证雾化工艺应用的关键性能。所使用的原料是(中和的)丙烯酸作为单体，这导致了聚丙烯酸钠的微粒。这种盐可以合成为线型聚合物或交联凝胶。此外，还评估了在喷雾聚合过程中是否有可能使现有的高分子链发生交联。

The vision of the SPP Process Spray is the evaluation of the interdependency of the fluid properties, spraying parameters and the properties of the synthesized powder. The process of spray-polymerization synthesizes a polymeric solid. The synthesis of the polymer form the monomer starts already within the spraying nozzle and is continued within the drop after atomization. The solid is formed due the reaction progress as well as due to the drying of the carrier solvent. In a one-step-process the process strategy combines the synthesis of the polymer with the design of the particle properties, which typically needs at least two independent steps. The spray polymerization is supposed to allow the synthesis of polymeric particles in the size range of 5-100 µm with specified particle properties. A special technical challenge here is the integrated crosslinking of the polymer. The state of technology has only limited options to produce defined polymeric particles in the size range from 1-50 µm. Emulsion- and suspension polymerization lead to compact dense spherical particles. The top-down approach by dry fine milling has severe problems in reaching a particle size below about 50 µm due to the elastic properties of the polymer material. A patent review shows a prove of principle for spray polymerization, but no quantitative data related to process design. The kinetic of the combined polymerization reaction and drying process is the main focus of experimental work in lab and pilot scale, it goes along with a theoretical description of the reaction. The technical realization also needs the development of a specialized technical components to control the start phase of the reaction. The layout of these components is strongly supported by lab scale characterization of the polymerization within an analytical rheometer, providing the relation of reaction progress and viscosity. The latter is the key property to ensure the application of the atomization process. The materials used are (neutralized) acrylic acid as monomer, which leads to particles of poly- -acrylic-acid sodium salt. This salt is synthezied either as linear polymer or as crosslinked gel. Furthermore it is also evaluated whether it is possible to crosslink existing polymer chains during spray polymerization.