Slot die pre metered coating process for organic coating of architectural steels

该项目将研究将槽模涂料作为一种在钢结构建筑的外立面上涂覆钢材的方法的可行性。。该项目旨在加深对缝隙模具和窗帘涂层工艺的了解，使其能够为钢铁工业沉积高粘度的溶剂型涂层。这些工艺潜在地提供了一种更具可重复性和可控性的涂料沉积方法，同时还允许更光滑的表面、更短的颜色转换时间、湿涂层上的多层湿涂层以及减少操作员暴露在VOCs中。它将使用建模和实验技术的组合来研究当基板-芯片接触必须通过增加基板/芯片表面来缓解时工艺的操作范围。通过了解与流变学、基材润湿、自由流动和表面流动相关的基本物理机制，将了解沉积过程。WP1-涂层流变性与所有液体涂层工艺一样，液体涂层的流变性与其沉积特性之间存在交互作用。WP1将利用受控应力和振荡流变学来研究液体涂层的物理流动特性。这将检查当前的涂料配方、通用模型涂层和定制结构WP1还将检查镀锌钢衬底上涂层的润湿特性。WP1的主要成果是了解槽模具涂层必须在其下运行的材料包络限制，以及了解如何改进配方以提高沉积质量WP2-模具涂层特性WP2将解决镀锌钢衬底的槽模具涂层的实际方面。这将主要是使用实验室板材槽式模具涂布机在特定位置安装模具/垫片，这些模具/垫片是根据WP1中的流变特性和在塔塔其他研发活动中积累的经验选择的。参数研究将是为了了解主要的控制策略并开发该过程的操作窗口。这也将考察从“亲吻”到窗帘涂层模式转变的影响。在KISS模式下，基板与芯片的距离较小，需要对基板厚度和平整度有更严格的公差，而窗帘模式可以容忍基板尺寸的变化，但速度稳定性较差。涂层钢样将使用包括扫描电子显微镜和WLI在内的各种技术进行表征。WP2的主要输出是定义的操作包络，WP3的验证，以及在实验室规模通过缝隙模具一致地制造样品的方法。WP 3-模型化本WP将专注于开发可用于确定液体涂料的操作极限和配方边界的工艺模型。对于简单的液体，预测模型存在这两种策略，但一旦考虑到非牛顿颗粒物质，这些预测的质量就会降低，因为许多基本假设是不正确的。将在WP中规定的时间点进行审查，以检查哪种方法对材料特性、操作参数和涂层均匀性之间的关系提供了最有希望的洞察。WP4-涂层性能评估WP2中创建的钢样的性能特征将接受标准的实验室测试，以评估沉积过程的变化对产品功能是否有任何有利或不利的影响WP5-系统规范WP5将汇集从实验和建模工作包中学到的知识，以制定槽/滑模线圈涂层系统的材料和操作规范。

The project will examine the feasibility of using slot die coating as a means of coating paint to steel which is used for exterior facades on steel buildings. . The project aims to develop the understanding of the slot die and curtain coating processes to allow it to deposit a high viscosity solvent based coating for the steel industry. The processes potentially offer a more repeatable and controlled means of depositing the paint, while also allowing smoother surfaces, shorter changeover times between colours, multi-layer wet on wet coating and reduced operator exposure to VOCs. It will use a combination of modelling and experimental techniques to investigate the operational envelope of the process when substrate - die contacted must be mitigated by an increased substrate / die surface. Through understanding of the underlying physical mechanisms associated with rheology, substrate wetting, free and surface flows, the deposition process will be understood. WP1 - Coating rheological characterizationAs with all liquid coating processes, there is an interaction between the liquid coating rheology and its deposition characteristics. WP1 will utilize controlled stress and oscillatory rheometry to investigate the physical flow characteristics of liquid coatings. This will examine current paint formulations, generic model coatings and bespoke formations WP1 will also look to examine the wetting characteristics of the coating on the galvanized steel substrate. The primary output from WP1 is an understanding of the material envelope limitations under which the slot die coating must operate and the understanding of how the formulation can be refined in order to improve the deposition quality WP 2 - Die coating characterizationWP2 will address the practical aspects of slot die coating of galvanized steel substrates. This will predominantly be carried out using a laboratory sheet slot die coater at SPECIFIC fitted with a die / shims which have been selected according to the rheological characterization in WP1 and that experience which has already been gathered in other TATA R&D activities. Parametric studies will be to understand primary control strategies and develop the operating window for the process. This will also examine the impact of the transition from "kiss" to curtain coating mode. In kiss mode, substrate - die distances are small requiring tighter tolerances on substrate thickness, flatness while curtain mode is tolerant to changes in substrate dimensions but can be less stable at speed. Coated steel samples will be characterized using a variety of techniques including SEM and WLI. The primary outputs from WP2 are a defined operational envelope, validation for WP3 and a means of consistent manufacture of samples through slot die at laboratory scale. WP 3 - ModellingThis WP will focus on developing process models which can be used to determine operational limits and formulation boundaries for the liquid coating. Predictive models exist either strategy for simple liquids, but the quality of these predictions reduces once non-Newtonian particulate laden materials are considered as many fundamental assumptions are incorrect. A review will be undertaken at a prescribed point in the WP to examine which methodology provides the most promising insight into the relationship between material properties, operational parameters and coating uniformity. WP4 - Coating performance evaluationThe performance characteristics of the steel samples created in WP2 will undergo standard laboratory testing to evaluate whether the change in deposition process has any beneficial or detrimental impact on product functionWP5 - System specificationWP5 will bring together the learnings from the experimental and modelling work packages to develop the material and operational specification of a slot / slide die coil coating system.