UV-Curable Overcoat for Electrostatic Printed Labels

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Solution Overview

Problem

Printed labels using electrostatic inks are vulnerable to chemical and water environments, leading to durability issues, especially in products exposed to wet conditions like shampoo and beer bottles.

Innovation Solution

A method involving a UV curable overcoat composition applied to electrostatically printed labels, comprising UV curable monomers or oligomers, a slip agent, and a photoinitiator, cured under UV irradiation with a power of 2500 W or less, enhancing durability and resistance to water and chemicals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If electrostatic inks are used for printing labels, then printing efficiency and coverage are improved, but durability and resistance to water/chemicals deteriorate

Engineering Contradiction:

Improveprinting efficiencyVSAvoiddurability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies a multi-layer composite structure consisting of electrostatic printed ink layers combined with UV-curable overcoat layers. The overcoat layers are formulated with specific resin systems (acrylic, polyester, polyurethane) and crosslinking agents to create a protective composite material that maintains the printability benefits of electrostatic inks while adding water and chemical resistance through the cured overcoat system.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent modifies the chemical and physical parameters of the ink system by introducing UV-curable components with specific functional groups (acrylate, methacrylate) and controlling the curing process parameters (UV irradiation dose, photoinitiator concentration). This transforms the ink from a simple electrostatic deposit to a crosslinked, chemically resistant network structure that maintains electrostatic printing efficiency while gaining durability.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If protective overcoats are applied to enhance durability, then resistance to water and chemicals is improved, but device complexity and process steps increase

Engineering Contradiction:

Improveresistance to water and chemicalsVSAvoidprocess steps

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple functions into integrated layers: the electrostatic ink layer serves both as the primary printing medium and as a substrate for the UV overcoat, while the overcoat itself provides multiple functions (protection, gloss, chemical resistance) in a single applied layer. This merging reduces the need for separate protective coating processes and simplifies the overall manufacturing workflow.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces traditional mechanical or thermal curing methods with UV photopolymerization. Instead of requiring high-temperature ovens or mechanical pressing to cure protective coatings, the system uses UV light irradiation to initiate rapid photopolymerization of the overcoat, significantly reducing equipment complexity and process time while achieving equivalent or superior protective properties.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Strength

If UV curing is used to enhance durability, then scratch resistance is improved, but energy consumption increases

Engineering Contradiction:

Improvescratch resistanceVSAvoidenergy consumption

Core Design Contradiction:

StrengthVSUse of energy by moving object

Solution Approach 1:

The patent employs periodic or pulsed UV irradiation rather than continuous high-power exposure. The curing process uses controlled UV doses delivered in specific time intervals, allowing the photoinitiators to efficiently polymerize the resin system without requiring sustained high energy input. This periodic action achieves full crosslinking and scratch resistance while minimizing total energy consumption compared to continuous thermal or high-power UV methods.

Inventive Principle:

Principle #19Periodic action

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 significantly increases the durability and scratch resistance of printed labels, maintaining visibility and integrity under various environmental conditions, including water exposure.

Implementation Method 1

curing the overcoat composition under UV irradiation

Methodology Applied

Scientific EffectPhotopolymerisation: Photopolymerisation

Data Source

PatentEP3541879B1labels

Publication Date: 2022.11.09 HP INDIGO BV

Figure 1~2
Figure 3

AI summary

Herein is described a method of providing a printed label. The method comprises: providing a printed label substrate having disposed thereon an electrostatically printed ink; applying a UV curable overcoat composition to the printed ink, wherein the UV curable overcoat composition comprises (i)a component selected from UV curable monomers and UV curable oligomers, and (ii)a slip agent; curing the overcoat composition under UV irradiation with an output power of 2500 W or less. Printed labels and an ink and overcoat composition set are also described herein.