Offset Coating Knives for Multilayer Film Thickness Control
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Solution Overview
Problem
Existing methods for forming multilayer films, such as die-coating, face challenges with layer uniformity, thickness control, and adhesion due to physical mixing and thickness variations, especially when forming thin layers or using high-viscosity precursors, leading to delamination and surface roughness issues.
Innovation Solution
A continuous self-metered process using offset coating knives to form multilayer films with substrate and outlet gaps, allowing precise control of layer thickness, especially for thin layers, and simultaneous application of a release liner to prevent exposure and mixing, resulting in uniform and stable films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If die-coating method is used to form multilayer films, then coating process is established, but layer uniformity and thickness control deteriorate due to physical mixing and thickness variations
Solution Approach 1:
The coating apparatus is divided into multiple independent coating units, each with its own coating knife and gap formation mechanism. This segmentation allows independent control of each layer's thickness and positioning, eliminating the physical mixing problem that occurs in conventional die-coating where all layers are coated simultaneously in a single die.
Solution Approach 2:
The coating knives are pre-positioned at specific offsets from the substrate to create predetermined gaps before the coating process begins. This preliminary arrangement of coating knives at controlled positions enables precise thickness control from the start of coating, preventing thickness variations and physical mixing that occur during the coating process in conventional methods.
2Manufacturing precision
If thin layers are formed with high-viscosity precursors, then layer thickness is reduced, but adhesion deteriorates due to delamination
Solution Approach 1:
The coating process continues without interruption as the substrate moves continuously through the coating apparatus. Each coating knife continuously applies its layer immediately after the previous layer is deposited, ensuring continuous coverage and eliminating gaps or defects that would compromise adhesion in thin-layer structures.
Solution Approach 2:
The offset coating knives act as intermediaries between the precursor material and the substrate. By positioning the knives at specific offsets that create gaps, they control the thickness of the thin layers while ensuring proper material distribution and bonding, preventing delamination even in thin-layer structures.
3Ease of manufacture
If conventional coating methods are used, then coating process is simple, but surface roughness issues occur leading to film quality deterioration
Solution Approach 1:
The conventional die-coating mechanical system is replaced with a knife-based coating system where coating knives mechanically define the layer thickness through controlled gaps. This substitution provides superior control over layer thickness and surface smoothness, eliminating the surface roughness issues inherent in die-coating while maintaining process simplicity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process achieves high uniformity and stability in multilayer film formation with precise control over layer thickness, reduced mixing, and improved adhesion, even with high-viscosity precursors, resulting in films with enhanced mechanical properties like T-peel strength.
Implementation Method 1
providing two or more coating knives which are offset, independently from each other, from said substrate and/or from an adjacent coating knife to form at least one substrate gap relative to the surface of the substrate and at least one outlet gap relative to the surface of an adjacent coating knife
Implementation Method 2
moving the substrate relative to the coating knives in a downstream direction
Implementation Method 3
curing the precursor of the multilayer film thus obtained
Data Source
AI summary
The invention relates to a continuous self-metered process of forming a multilayer film comprising at least two superimposed polymer layers comprising the steps of: (i) providing a substrate (5); (ii) providing two or more coating knives (2, 3, 4) which are offset, independently from each other, from said substrate (5) and/or from an adjacent coating knife to form at least one substrate gap (9) relative to the surface of the substrate (5) and at least one outlet gap (10) relative to the surface of an adjacent coating knife; (iii) moving the substrate (5) relative to the coating knives (2, 3, 4) in a downstream direction (6), (iv) providing curable liquid precursors of the polymers (I, II, III) to the upstream side of the coating knives (2, 3, 4) thereby coating the two or more precursors (I, II, III) through the respective gaps (9, 10) as superimposed layers (12, 13, 14) onto the substrate (5); (v) optionally providing one or more solid films (1 1) and applying these essentially simultaneously with the formation of the adjacent lower polymer layer, and (vi) curing the precursor of the multilayer film thus obtained; wherein a lower layer of a curable liquid precursor (I, II, III) is covered by an adjacent upper layer of a curable liquid precursor (I, II, III) or a film (1 1), respectively, essentially without exposing said lower layer of a curable liquid precursor (I, II, III).