Photopolymer formulation to minimize feature size, surface roughness, and stair-stepping in digital light processing-based three-dimensional printing
Photopolymer formulation to minimize feature size, surface roughness, and stair-stepping in digital light processing-based three-dimensional printing
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DOI：
10.1016/j.addma.2018.10.037
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发表时间：
2018-12-01
影响因子：
11
通讯作者：
Ge, Qi
中科院分区：
文献类型：
--
作者：
Kowsari, Kavin;Zhang, Biao;Ge, Qi
实现优化的横向和垂直分辨率是获得通过基于数字光处理（DLP）的3D打印技术制造的三维（3D）结构细节的关键因素，该3D打印技术利用数字化紫外（UV）或近UV光来触发局部光聚合，从而从液体聚合物树脂形成固体图案。已经做出了许多努力来通过改进光学系统来优化打印分辨率。然而，研究人员对聚合物配方对印刷分辨率和表面质量的影响的关注相对较少。在这里，我们报告了一项关于内部配制的（甲基）丙烯酸酯基光聚合物成分类型和浓度对基于底部曝光DLP的3D打印系统上打印的结构的分辨率和质量的影响的调查。我们研究了各种各样的树脂配方，以确定最佳配方，从而在合理的广泛机械性能范围内获得最佳打印分辨率和表面质量。我们展示了亚像素圆锥形和非球面光滑特征的受控制造，从而可以用树脂配方和工艺参数来规定形状和尺寸。这些特征在使用基于DLP的3D打印技术的微光学和微流体制造中具有很好的应用前景。此外，我们设计了基于二（甲基）丙烯酸酯的树脂制剂，其可以专门产生光学透明层，而不是由常用的基于二丙烯酸酯的树脂（包括可商购的那些）产生的不透明、粗糙表面。使用这种解决方案可以最大限度地减少以逐层方式打印的组件中的“阶梯效应”。我们还表明，最大的横向和垂直分辨率可达到使用我们目前的系统分别为7 μ m和4 μ m，同时保持统一的宽度和高度。总之，本发明的发现为优化的光聚合物树脂制剂提供了基础，所述光聚合物树脂制剂保持最大的垂直和横向分辨率以及最小的表面粗糙度和分层伪影，以获得适用于光滑自由形式固体的3D打印、微光学和具有功能表面的微流体平台的直接制造中的新型应用的多种机械和流变性质。
Achievement of optimized lateral and vertical resolution is a key factor to obtaining three-dimensional (3D) structural details fabricated through digital light processing (DLP)-based 3D printing technologies which exploit digitalized ultraviolet (UV) or near-UV light to trigger localized photopolymerization forming solid patterns from liquid polymer resins. Many efforts have been made to optimize printing resolution through improving the optical systems. However, researchers have paid comparatively little attention to understand the influences of polymer formulation on the printing resolution and surface quality. Here, we report an investigation on the effects of in-house formulated (meth)acrylate-based photopolymer constituent types and concentrations on the resolution and quality of structures printed on a bottom-exposure DLP-based 3D printing system. We examined a wide variety of resin formulations to determine optimal formulations that yield best printing resolution and surface quality over a reasonably broad range of mechanical properties. We demonstrated the controlled fabrication of sub-pixel conical and aspherical smooth features, whereby the shape and dimensions could be prescribed with the resin formulation and process parameters. Such features hold promising implications in micro optic and microfluidic fabrication using the DLP-based 3D printing technique. Additionally, we devised di(meth) acrylate-based resin formulations which could exclusively produce optically-clear layers in contrast to opaque, rough surfaces resulting from commonly-used diacrylate-based resins including those available commercially. Use of this solution minimized the 'stair-stepping' effect in components printed in a layer-by-layer manner. We also showed that the maximum lateral and vertical resolution attainable using our present system were 7 mu m and 4 mu m, respectively, while maintaining uniform width and height. Taken together, the present findings provide a basis for optimized photopolymer resin formulations that retain maximum vertical and lateral resolutions and minimal surface roughness and layering artifacts for a versatile range of mechanical and rheological properties suited to novel applications in 3D printing of smooth free-form solids, micro-optics, and direct fabrication of microfluidic platforms with functional surfaces.