Researchers from the Lithuania-based维尔纽斯大学and theKaunas University of Technology已经开发了一种环保的，可回收的树脂，可在光学3D打印（O3P）过程中使用。
生物金来自大豆，满足了3D打印中使用的常规聚合物的技术，功能和耐用性要求，同时以较低的成本提供了增强的生物兼容性。新的生物材料可用于小批量生产服务，将O3DP制造转向使用基于生物的树脂，而不是非回收石油的光聚合物。
A greener alternative to photopolymers in 3D printing
Bio-based polymers are increasingly being adopted within the 3D printing industry as an alternative to photopolymers due to their carbon neutrality, biodegradability, and recyclability. Vegetable oil for instance, is widely available, and can be used as a starting material for many polymer-substitutes, while displaying an inherent degradability and low toxicity. O3DP methods, meanwhile, have also been developed as a way of achieving low waste production, but many still rely on petroleum-derived resins.
O3DP manufacturing methods offer many benefits, such as its integration of post-processing, which allows for the fabrication of free-form structures that serve as 3D templates for producing pure glass, ceramic and metal objects. In addition, the production techniques allow the flexible manufacturing of multi-dimensional, hierarchical, or arbitrary structures, which accelerates the 3D printing process within a range of applications.
In order to continue reaping the benefits of O3DP printing, albeit in a more environmentally-friendly way, the Lithuanian researchers devised their new biopolymer. The resin, constructed from soybean extracts, is suitable for O3DP in the scales from nano- (hundreds nm) to macro-dimensions (cm). Moreover, by optimizing pulsed-exposure during printing, the resin can be processed purely, and without the need to add any artificial photoinitiators (PIs).
测试和分析环保树脂
根据其应用，树脂需要不同的辐射强度和可实现的分辨率，并且团队选择了丙烯酸化的环氧化豆油（AESO）来证明基于生物的树脂在O3DP中的适用性。例如，大多数桌面3D打印机与丙烯酸酯或甲基丙烯酸酯的树脂兼容，用于宏观对象的原型化。Nanoscribe另一方面，提供了一种多尺度的2PP材料，但实际上使用了三种不同的光蛋白，这些光蛋白旨在为每个空间尺度生产零件。根据立陶宛团队的说法，没有一个照片树脂能够实现真正可扩展的制造。
同时，Aeso材料的优点是适合于跨越五个数量级的制造物体。此外，根据研究人员的说法，不仅缺乏诸如PIS之类的光吸收化合物，还使其生物棒适合与O3DP方法一起使用。材料的最终化学制剂，物理特性，粘度和反应机制在确定其3D照片结构质量和可回收性方面也具有重大影响。
立陶宛团队使用标准FormLabs Form 2 Optical System上的深灯投影仪（DLP）3D打印，在不同尺度上生产了一系列的板凳标记样品。这些型号包括两个名为“ Tower”和“ Marvin”的象棋式碎片，这是一种非线性光刻（NLL） - 印刷脚手架结构，并达到数百万μm的外部尺寸，并且只有几次单个特征。根据该团队的说法，这些部分的特征证明了其树脂适用于商业上提供小批量生产服务，此外除了快速原型制作外。
ASIGA PICO2 39 UV和Autodesk Ember DLP 3D打印机被公开用于测试定制的树脂，以实现线性吸收和适合宏观添加剂制造。印刷对象显示出与使用聚合物树脂生产的对象相似的层厚度，并且其他NLL测试使用了常见的激光光刻设置，该设置方便3D打印精确的MM尺度原型。此外，证明了特征大小小于1μM的周期结构的精细制造，这意味着生产不限于笨重的整体物体。
Overall, the AESO resin had demonstrable performance advantages over existing resins used with O3DP, as it can be processed with either DLP or NLL printing, while maintaining over 60% of its bio-renewable carbon. In addition, the rheological and optical properties of AESO were easily modified by mixing it with diluents and PIs, enabling the team to produce multi-scale (from hundreds nm to cm) objects from a single material.
的》cal properties of the AESO resin such as its elastic modulus, tensile strength and elongation at break, are still being investigated and results will be published separately according to the team. Nonetheless, the resin’s demonstrated compatibility with a range of O3DP techniques, could make it radically simpler and more affordable for desktop 3D printer owners to manufacture products, and in a more eco-friendly way.
Environmentally-friendly initiatives in 3D printing
A series of studies have been commissioned in recent years, aiming to assess the overall environmental impact of 3D printing.
全球贸易集团Additive Manufacturer Green Trade Association(AMGTA) for instance,announced a系统评价into the environmental sustainability of metal 3D printing in June 2020. The organization’s first literary-based appraisal aims to promote the green benefits of additive manufacturing.
Researchers from马萨诸塞州理工学院(MIT),Yale Universityand the诺丁汉大学警告说3D打印被高估了in September 2018. The team’s research suggested that on-demand 3D printing and rapid prototyping could lead to “dramatic increases in throw-away consumer products.”
In December 2017, a special edition of the “Journal of Industrial Ecology” produced at the耶鲁大学林业与环境研究学校(F&ES) warned that it wastoo early to conclude that 3D printing was sustainable。研究人员指出，大多数研究都获得了好处，而不是3D印刷的生态影响的弊端。
The researchers’ findings are detailed in their paper titled “A Bio-Based Resin for a Multi-Scale Optical 3D Printing”发表在Scientific Reportsjournal on June 16th 2019. The report was co-authored by Edvinas Skliutas, Migle Lebedevaite, Sigita Kasetaite, Sima Rekštytė, Saulius Lileikis, Jolita Ostrauskaite and Mangirdas Malinauskas.
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Featured image shows the polymerization process used by the researchers in the development of their eco-resin. Image via Scientific Reports.
