Epilame Copolymer Coating for Wash-Resistant Watch Substrates

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Solution Overview

Problem

Existing epilame agents face issues such as low resistance to watch washing, limited material compatibility, complex synthesis processes, and environmental regulatory concerns, particularly with the use of fluorinated substances.

Innovation Solution

A copolymer comprising M and N units covalently bonded through their main chains, with optional V units for concentration control, is used to create an epilame agent that adheres to various substrates, offering improved wash resistance and environmental sustainability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional epilame agents (e.g., Fixodrop) are used, then the surface energy is reduced and oleophobicity is achieved, but the resistance to watch washing is insufficient and material compatibility is limited

Engineering Contradiction:
Improvewash resistanceVSAvoidmaterial compatibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The copolymer epilame agent is designed with dual functionality: the M units provide universal anchoring capability through covalent bonding to diverse substrate surfaces (metal, ceramic, polymer, sapphire), while the N units provide the oleophobic epilame effect. This multi-functional design allows a single agent to work across all watchmaking materials while maintaining high wash resistance.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The invention uses a composite copolymer structure combining two distinct functional units (M and N) in a single polymer chain. The M units contain anchoring groups for substrate attachment, while the N units contain fluorinated chains for oleophobicity. This composite approach integrates multiple functions into one material, resolving the contradiction between reliability and adaptability.

Inventive Principle:
Principle #40Composite materials

2Reliability

If fluorinated epilame agents (e.g., C6F13 units) are used to achieve high-performance epilame effects, then oleophobicity is improved, but environmental regulatory pressure increases

Engineering Contradiction:
Improveepilame performanceVSAvoidenvironmental impact
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention modifies the chemical structure of the fluorinated units by replacing some fluorine atoms with hydrogen atoms in the N units, creating a partially fluorinated structure. This parameter change reduces the environmental persistence and toxicity associated with fully fluorinated compounds while maintaining sufficient oleophobic performance for watchmaking applications.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention acknowledges the environmental concerns with fluorinated substances but converts this challenge into a benefit by using reduced-fluorine-content units that provide adequate epilame performance without the severe environmental persistence and bioaccumulation problems of traditional perfluorinated compounds.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If mixed epilame compositions (thiol and bisphosphonic compounds) are used to achieve synergistic adhesion, then adhesion to substrate is improved, but the synthesis process becomes long and complex

Engineering Contradiction:
Improveadhesion strengthVSAvoidsynthesis complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention merges the adhesion function and the epilame function into a single copolymer molecule. The M units provide anchoring through covalent bonding to substrates, while the N units provide oleophobicity. This unified structure eliminates the need for separate thiol and bisphosphonic compounds, simplifying both the agent formulation and the synthesis process while maintaining strong adhesion.

Inventive Principle:
Principle #5Merging (Combining)

4Reliability

If perfluorohexanoic acid and related substances are used for epilamation, then effective surface treatment is achieved, but environmental regulatory pressure increases

Engineering Contradiction:
Improvesurface treatment effectivenessVSAvoidregulatory pressure
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention changes the chemical composition parameters of the epilame agent by using copolymers with reduced fluorine content (partial fluorination) instead of fully fluorinated compounds like perfluorohexanoic acid. This parameter modification maintains effective surface treatment performance while reducing environmental persistence, bioaccumulation, and toxicity concerns that drive regulatory pressure.

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 copolymer provides high-performance epilame effects with enhanced wash resistance and universal applicability across materials, while avoiding regulatory pressures and reducing the use of polluting fluorinated solvents.

Implementation Method 1

M units and N units are associated by covalent bonds through their main chains

Methodology Applied
Scientific EffectCovalent bonding: Chemical Bonding

Implementation Method 2

The copolymer provides high-performance epilame effects with enhanced wash resistance and universal applicability across materials

Methodology Applied
Scientific EffectAdsorption: Adsorption

Data Source

PatentEP4394020B1Substrate comprising a surface coated with an epilame agent and method for epimerising such a substrate
Publication Date: 2025.07.16 THE SWATCH GRP RES & DEVELONMENT LTD
  • EP4394020B1 patent drawingFigure 1~3
  • EP4394020B1 patent drawingFigure 4
  • EP4394020B1 patent drawingFigure 5

AI summary

The invention relates to a substrate comprising a surface at least a part of which is coated with an epilame agent, characterized in that said epilame agent comprises at least one compound in the form of a copolymer comprising M units and N units, associated by covalent bonds by their main chains, where M is N is where R1 and R2, identical or different, are H, a C1-C10 alkyl group, a C2-C10 alkenyl group; X and Y, identical or different, are spacer arms consisting of a heteroatom or a hydrocarbon chain containing at least one heteroatom, linear or branched, comprising at least one carbon atom; A, identical or different, constitutes a substrate anchoring group; L, identical or different, is a halogenated ether group according to formula (I) where Q is a halogen atom;P, identical or different, is a C1-C10 alkyl group or a C2-C10 alkenyl group comprising at least one halogen atom and being linear or branched; p is chosen between 1 and 4; and n is chosen between 1 and 20. The invention also relates to a method for de-pilling such a substrate, as well as a watch or jewelry component comprising an element containing such a substrate.