| With the prospect of extremely fast manufacture of very low cost devices, organic electronics prepared by thin film processing techniques that are compatible with roll-to roll(R2R) methods in emerging field of optoelectronic and energy are presently receiving an increasing interest and industrialization research. The paper aimes at the micro-gravure coating which is widely used in precision coating technology, improving the coating uniformity and precision thickness control as the entry point, focuses on the micro-gravure coating mechanism of great influence on the coating thickness and uniformity in the doctor blade wear and its mechanisms and analyzes how the wear of doctor blade effect on the coating thickness and uniformity. And to provides a theoretical basis so as to improve the accuracy of micro-gravure coating. The main research contents are as follow:(1) Firstly, on the doctor blade working condition, this paper has analysed the model of doctor blade set film thickness, which based on the lubrication theory and obtained downstream distance form roller surface layer thickness ∞. Secondly, on the micro-mechanism of wear, this paper has compared and analysed the estimation of sliding wear of adhesive wear volume and abrasion wear volume and the variety of worn surface morphologies under different operating conditions. Thirdly, on the macro behavior of wear, this paper has established the macro theoretical model of doctor blade wear and the wear stage theory under actual working conditions: based on cantilever beam model, simultaneous equations of large deflection model of AB beam and the stepped beam small deflection model of BC, analysis of the direct force worn area OCDE and the wear process is divided into three stages according to contour of section.(2)Online experimental data presented that the worn area ? of carbon steel doctor blade increases at first then decreases with an increase in characteristic pressure. As roll linear speed increasing, the ? has a positive linear correlation with sliding distance S. With increase of the viscosity of the coating liquid, ? is trending downward overall. The wear process of carbon steel doctor blade can be divided into stages of run-in and comparatively steady wear. Ni-based alloy ceramic doctor blade wear steadily, wear rate showed an oscillating at first, then became stable, and finally gradually increasing trend.. On the whole, a micro grinding effect is produced in worn surface. For plastic carbon steel material, there mainly are abrasive and adhesive wear in worn surface. For Ni-based alloy ceramics coatings, there mainly are ductile-mode cutting in hard-brittle material. The wear debris of carbon steel are between dozens of nanometers to a few micrometers in particle size. The coating liquid lubricanted. But on dry friction condition, soft carbon steel material self lubrication to reduce friction and wear.(3) According to the analysis of coating defects due to doctor blade and its causes, doctor blade wear leads to its overall length and blade tip ―heel‖ shape difference makes the set thickness of unstable. Doctor blade offset results in deviation of the left-most and right-most coating thickness. The ―Rainbow Stripe‖ is formed by the interference of light when the coating thickness is non uniform. When the rainbow stripe is not obvious, the peak-valley of spectrum curve appears more uniform and there is no significant fluctuations and absorption region. On the contrary, when the rainbow stripe is obvious, the spectrum curve fluctuated remarkably, the reflection increase and light absorption in a specified band occurred. The air bubble in the coating layer of optical film comes mainly from the coating liquid, substrate surface defects and the air entrainment. The round bubbles diameter is relatively uniform, between 10μm to 15μm. But the bubble surface layers with various morphologies are formed by the air bubble location, bubble surface layer film curing condition, bubble expansion and cooling. |
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