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

该项目将研究使用槽模涂料作为钢结构建筑物外立面用钢涂料的可行性。.该项目旨在发展对狭缝模头和幕涂工艺的理解，使其能够为钢铁行业存款高粘度溶剂型涂料。该工艺可能提供更可重复和可控的涂料沉积方法，同时还允许更光滑的表面，更短的颜色之间的转换时间，多层湿对湿涂层和减少操作员暴露于VOC。它将使用建模和实验技术相结合，以调查的过程中，基板-芯片接触时，必须通过增加基板/芯片表面减轻操作包络。通过理解与流变学、基底润湿、自由流动和表面流动相关的基本物理机制，将理解沉积过程。WP 1-涂料流变特性与所有液体涂料工艺一样，液体涂料流变性与其沉积特性之间存在相互作用。WP 1将利用受控应力和振荡流变仪来研究液体涂层的物理流动特性。这将检查当前的油漆配方，通用模型涂层和定制的形成WP 1也将检查涂层在镀锌钢基材上的润湿特性。WP 1的主要输出是对狭缝模头涂层必须在其下操作的材料包络限制的理解，以及对如何改进配方以提高沉积质量的理解WP 2 -模头涂层表征WP 2将解决镀锌钢基材的狭缝模头涂层的实际问题。这将主要使用SPECIFIC的实验室片材狭缝模头涂布机进行，该涂布机配有根据WP 1中的流变特性和在其他TATA研发活动中已经收集的经验选择的模头/涂布机。参数研究将理解主要的控制策略，并为工艺开发操作窗口。这也将检查从“吻”到幕式涂布模式的过渡的影响。在接触模式中，衬底-管芯距离小，需要对衬底厚度、平坦度的更严格的公差，而帘幕模式容许衬底尺寸的变化，但在速度上可能不太稳定。涂层钢样品将使用各种技术进行表征，包括SEM和WLI。WP 2的主要输出是定义的操作范围、WP 3的验证和通过实验室规模的狭缝模头一致生产样品的方法。WP 3 -建模该WP将专注于开发可用于确定液体涂料的操作限制和配方边界的工艺模型。对于简单液体，存在两种策略的预测模型，但一旦考虑非牛顿颗粒负载材料，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最有希望的见解。WP 4-涂层性能评估WP 2中创建的钢样品的性能特征将进行标准实验室测试，以评估沉积工艺的变化是否对产品功能产生任何有益或有害的影响WP 5-系统规范WP 5将从实验和建模工作包中吸取经验教训，以开发槽/滑动模具卷材涂布系统。

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.