Polyurethane Coating for Watch Recesses

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Solution Overview

Problem

Existing decorative coatings for watch components lack intense color options, are not conformal to recess surfaces, and have poor resistance to scratches, environmental conditions, and ultraviolet degradation.

Innovation Solution

A polyurethane-based conformal coating composition that includes a binder, pigments, fillers, and solvents, applied in recesses of watch components to provide intense colors with enhanced scratch resistance and ultraviolet radiation resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If conventional PVD metallic coatings are used, then the coating can be deposited, but the available metallic colours are limited and intense colours cannot be achieved

Engineering Contradiction:
Improvecolour intensityVSAvoidavailable metallic colours
Core Design Contradiction:
Quantity of substanceVSAdaptability or versatility

Solution Approach 1:

The patent changes the fundamental parameter of the coating material from metallic PVD coatings to organic polymer-based coatings with pigments. This allows achieving intense colours that were impossible with conventional metallic PVD coatings, directly resolving the contradiction between colour intensity and colour variety.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If thin coloured coatings are applied only to the bottom of recesses, then scratch resistance is improved, but the side walls of recesses are not coated and the visual aspect is affected

Engineering Contradiction:
Improvescratch resistanceVSAvoidcontour uniformity
Core Design Contradiction:
ReliabilityVSShape

Solution Approach 1:

The patent uses a composite coating system consisting of multiple layers: a first coating layer applied to the bottom of recesses for scratch resistance, and a second conformal coating layer applied to all surfaces including side walls for uniform visual appearance. This multi-layer composite approach resolves the contradiction between scratch resistance and contour uniformity.

Inventive Principle:
Principle #40Composite materials

3Quantity of substance

If organic matrix coatings with ceramic particles are used to fill recesses, then intense colours can be achieved, but the coating requires polishing to be flush with the upper surface

Engineering Contradiction:
Improvecolour intensityVSAvoidpolishing requirement
Core Design Contradiction:
Quantity of substanceVSEase of manufacture

Solution Approach 1:

The patent changes the formulation parameters of the organic matrix coating by optimizing the ratio of organic matrix to ceramic particles and using specific polymer resins that cure to form a coating flush with the substrate surface without requiring polishing, while maintaining intense colour through pigment selection.

Inventive Principle:
Principle #35Parameter changes

4Ease of manufacture

If conventional varnishes or lacquers are applied to recesses, then the coating can be applied easily, but the resistance to environmental conditions and ultraviolet degradation is poor

Engineering Contradiction:
Improvecoating applicationVSAvoidenvironmental resistance
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent uses a composite coating formulation combining organic polymer matrices with inorganic ceramic particles and UV-stabilizing additives. This composite structure maintains the ease of application of organic coatings while significantly improving resistance to environmental conditions and ultraviolet degradation through the inorganic components.

Inventive Principle:
Principle #40Composite materials

5Shape

If conformal coating is applied to all surfaces of recesses, then the visual aspect is improved, but the resistance to scratches and environmental conditions deteriorates

Engineering Contradiction:
Improvecontour uniformityVSAvoidscratch and environmental resistance
Core Design Contradiction:
ShapeVSReliability

Solution Approach 1:

The patent employs a multi-layer composite coating system where a first layer provides scratch and environmental resistance, and a second conformal layer provides uniform visual appearance. The composite structure of multiple functional layers resolves the contradiction between contour uniformity and durability.

Inventive Principle:
Principle #40Composite materials

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 coating achieves high abrasion and scratch resistance, maintains color integrity under ultraviolet exposure, and provides a visually appealing, conformal finish that enhances the aesthetic and functional durability of watch components.

Implementation Method 1

Actual solutions for conformal coatings are either limited in the available metallic colours that can be deposited by PVD

Methodology Applied
Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Implementation Method 2

The coating shows an intense colour with enhanced resistance to ultraviolet radiation and other environmental influences

Methodology Applied
Scientific EffectUV resistance: Absorption (EM radiation)

Implementation Method 3

The coating achieves high abrasion and scratch resistance

Methodology Applied
Scientific EffectAbrasion resistance: Abrasion

Data Source

PatentEP3819718B1Coloured coating adapted for watch components
Publication Date: 2025.02.19 ROLEX SA
  • EP3819718B1 patent drawingFigure 1~3
  • EP3819718B1 patent drawingFigure 4~6
  • EP3819718B1 patent drawingFigure 7

AI summary

Disclosed is a coating composition for watch elements, comprising • a binder, preferably a two-component polyurethane; • one or more pigments, preferably in quantities from 19 to 58% by weight of pigments (based on total solids of the composition); • at least one filler; • a solvent or a solvent combination, preferably butyl acetate and/or ethyl lactate. • optionally one or more commonly used additives, customary auxiliaries or combinations of them. Further disclosed are a kit-of-parts, a coating on a watch element, a process for coating a watch element and a watch obtainable by said process or comprising said coating.