Gravure Roll with Diamond-Like Carbon Coating
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Solution Overview
Problem
The gravure coating process using hard inorganic fillers like silica and alumina particles leads to roll abrasion and clogging of recesses on the gravure roll, resulting in impurities and uneven coating quality.
Innovation Solution
A gravure roll with a metal body, obliquely extending protrusions and recesses, entirely covered with a diamond-like carbon (DLC) layer, which is water-repellent and has a thickness between 0.1 to 3 micrometers, along with an intermediate layer of hard chromium for enhanced adhesion, preventing abrasion and clogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a gravure roll is used to coat a coating liquid containing hard inorganic fillers, then the coating process can be performed, but the gravure roll surface is abraded and recesses are clogged
Solution Approach 1:
The gravure roll employs a composite structure with a metal roll body and a DLC (diamond-like carbon) coating layer on the surface. This composite material approach provides both the mechanical strength of metal and the extreme wear resistance of diamond-like carbon, allowing the roll to withstand abrasion from hard inorganic fillers while maintaining surface integrity and coating precision.
2Manufacturing precision
If hard inorganic fillers are used in the coating liquid, then the desired coating properties are achieved, but the fillers aggregate and stick to the gravure roll surface
Solution Approach 1:
The invention changes the surface parameter of the gravure roll by applying a DLC coating layer with specific properties (extreme hardness, low surface energy, chemical inertness). This parameter change prevents filler aggregation and adhesion to the roll surface, allowing hard inorganic fillers to remain dispersed in the coating liquid and be transferred uniformly to the substrate.
3Ease of operation
If the gravure roll makes direct contact with the base film, then coating is achieved, but roll abrasion occurs at the protrusion summits
Solution Approach 1:
The invention applies local quality enhancement by coating only the surface layer of the gravure roll with DLC material. This localized treatment provides extreme wear resistance exactly where contact with the base film occurs (at the protrusion summits and recesses), while the bulk metal roll body maintains its mechanical properties. The DLC layer thickness is optimized to provide protection without interfering with the coating transfer function.
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 solution prevents roll abrasion and ensures stable, uniform coating by reducing friction and preventing inorganic fillers from sticking to the DLC layer, maintaining superior coating performance and uniformity.
Implementation Method 1
The gravure roll... entirely covered with a diamond-like carbon (DLC) layer... preventing abrasion and clogging
Implementation Method 2
a diamond-like carbon (DLC) layer, which is water-repellent and has a thickness between 0.1 to 3 micrometers... preventing inorganic fillers from sticking to the DLC layer
Data Source
AI summary
A gravure roll, in which the outside peripheral surface of a metal roll main body has a plurality of oblique line shaped protrusions forming a prescribed angle with the center axis of the roll main body and the coating liquid can be held in a plurality of oblique line shaped recesses formed between each of the plurality of protrusions, is configured such that the roll main body has a diamond-like carbon layer on the entire outer peripheral surface thereof, a head part for each of the plurality of protrusions is cut down, and each of the plurality of protrusions has a trapezoidal cross-sectional shape that becomes gradually narrower in width moving in direction toward the head part. A separator with a uniform weight per unit area can be manufactured wherein the coating liquid is coated onto a base material film using this gravure roll.