UV Inkjet Metal Coating for Plastic Surfaces

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Solution Overview

Problem

Existing coating systems for plastic surfaces with metal layers face challenges such as insufficient mechanical stability, difficulty in creating relief structures, and damage from decoration methods like lasering, which compromises the integrity of the coating and is not suitable for inline processes.

Innovation Solution

A coating system comprising a UV-curing inkjet ink layer, a PVD-deposited metal layer, and a clear UV-curing varnish layer, where the inkjet inks and varnishes are applied using commercially available inkjet printing and spray guns, respectively, to achieve a stable and decorative finish without damaging the surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a primer is applied under the PVD layer to improve surface quality, then the surface defects are reduced, but the process complexity and production time increase due to thermal drying requirements

Engineering Contradiction:
Improvesurface qualityVSAvoidprocess complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent removes the primer layer from the coating system, replacing it with a PVD metal layer that directly adheres to the plastic substrate. This extraction eliminates the thermal drying step and reduces process complexity while maintaining surface quality through the inherent properties of PVD deposition

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the thermal drying process (thermal system) with a PVD deposition process (physical vapor deposition). This substitution eliminates the need for thermal processing and associated drying time, reducing both process complexity and production time while achieving the desired surface quality

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If lasering is used to decorate the clear varnish layer, then patterns can be created, but the surface is damaged and infiltration occurs compromising coating integrity

Engineering Contradiction:
Improvedecoration capabilityVSAvoidcoating integrity
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

Instead of decorating the clear varnish layer (top layer), the patent inverts the approach by decorating the PVD metal layer (middle layer). This allows laser patterns to be created in the metal layer without damaging the overlying clear varnish, maintaining coating integrity while achieving decorative effects

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent performs the decoration action on the PVD layer before applying the clear varnish layer. This preliminary action allows patterns to be laser-etched into the metal layer in advance, and the subsequent clear varnish application seals and protects these patterns without compromising the coating structure

Inventive Principle:
Principle #10Preliminary action

3Strength

If a clear coat is applied over the metal layer to improve mechanical stability, then the coating becomes more durable, but the ability to create relief structures and decorate is reduced

Engineering Contradiction:
Improvemechanical stabilityVSAvoidrelief structure capability
Core Design Contradiction:
StrengthVSAdaptability or versatility

Solution Approach 1:

The patent segments the coating functions into distinct layers: the PVD metal layer handles both structural support and decoration, while the clear varnish layer provides mechanical protection. This segmentation allows each layer to optimize its specific function without compromising the others, enabling both relief structures and durable coating

Inventive Principle:
Principle #1Segmentation

4Adaptability or versatility

If conventional inkjet inks are used to apply patterns, then decoration is possible, but the low viscosity and high solvent content prevent formation of stable relief structures

Engineering Contradiction:
Improvedecoration capabilityVSAvoidrelief structure stability
Core Design Contradiction:
Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent changes the key parameter of ink viscosity by using UV-curing inks with higher viscosity and lower solvent content compared to conventional inkjet inks. This parameter change enables the ink to form stable relief structures that maintain their shape and provide a substrate for PVD metal deposition, while still being compatible with inkjet printing processes

Inventive Principle:
Principle #35Parameter changes

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 provides a mechanically stable and decorative coating system that can be integrated into inline processes, allowing for rapid surface finishing and meeting automotive specifications without compromising the structural integrity of the plastic components.

Implementation Method 1

In step (b), the applied inks are hardened to form the ink-containing layer by irradiation with UV light

Methodology Applied
Scientific EffectUV-curing: Photopolymerisation

Implementation Method 2

physical gas deposition or PVD processes (PVD: P physical V apor D eposition). Here, the starting material or the coating material is transferred into the gas phase using physical processes. The gaseous material condenses on the substrate to be coated, forming the target layer or coating

Methodology Applied
Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Implementation Method 3

The starting material can be converted into the gas phase via cathode sputtering or sputtering

Methodology Applied
Scientific EffectSputtering: Sputtering

Data Source

PatentEP2791383B1Method for producing coating systems containing metal layers for finishing plastic surfaces
Publication Date: 2015.12.09 MANKIEWICZ GEBR & CO GMBH & CO KG

AI summary

The invention relates to a method for coating plastic or glass surfaces. The method has the steps of applying a first layer onto the surface of a component, said layer being producible from UV-cured inks, applying at least one metal layer onto the first layer, and applying a terminating layer of a clear coating. The invention further relates to a coating system for substrate surfaces, said system containing a first layer which can be produced from UV-cured inkjet inks, one or more metal layers, and a terminating clear coating layer. The invention can be used in particular for decorating plastic components in an inline method.