Polyol-Based Electron Beam Curable Compositions for Thick Ink Films

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Solution Overview

Problem

Current UV-curable inkjet solutions face challenges in achieving satisfactory cure through thick ink sections due to UV attenuation, leading to residual uncured monomers and potential contamination in packaging applications, especially in food and pharmaceutical packaging.

Innovation Solution

Incorporating alcohols, particularly polyols like diethylene glycol, triethylene glycol, and trimethylolpropane, which are essentially free of ethylenically unsaturated groups, to promote Electron Beam (EB) curing of compositions comprising ethylenically unsaturated monomers and oligomers, reducing the amount of uncured monomers and minimizing migration risks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If UV-curable compositions are used for thick ink sections, then UV light penetration is required, but UV attenuation by pigments and photoinitiators prevents satisfactory cure at base levels

Engineering Contradiction:
Improvecure qualityVSAvoidUV light penetration
Core Design Contradiction:
Manufacturing precisionVSIllumination intensity

Solution Approach 1:

The patent replaces UV light-based curing (optical system) with electron beam curing (particle radiation system). Electron beams have much higher penetrating power through thick ink films containing pigments and photoinitiators, enabling complete cure at base levels where UV light is attenuated and cannot effectively polymerize monomers.

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

Solution Approach 2:

The patent changes the fundamental curing parameter from UV wavelength (100-400 nm) to electron beam energy (typically 50-200 keV). This parameter change allows the curing radiation to penetrate through thick ink sections (exceeding 20 μm) that completely block UV transmission, achieving uniform cure throughout the entire ink film thickness.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If conventional UV-curable inks are used, then photoinitiators are required for curing, but high concentrations of photoinitiators increase ink viscosity and cause migration issues

Engineering Contradiction:
Improvecure effectivenessVSAvoidink formulation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent eliminates the need for photoinitiators by replacing UV photochemical curing with electron beam-induced free radical curing. Electron beams directly ionize and excite monomer molecules, generating radicals without requiring photoinitiator mediators, thereby simplifying the ink formulation and eliminating migration issues associated with high photoinitiator concentrations.

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

3Object-affected harmful factors

If UV-curable inks are used for food packaging, then complete cure is required to prevent contamination, but UV attenuation leaves residual uncured monomers that can migrate

Engineering Contradiction:
Improvecontamination riskVSAvoidcure completeness
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent replaces UV curing with electron beam curing to achieve complete polymerization of monomers in thick ink films. The high penetrating power and direct energy transfer of electron beams ensure that even monomers at the base level of thick ink sections (exceeding 20 μm) are fully cured, eliminating residual uncured monomers that could migrate and contaminate food products.

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

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 use of polyols significantly reduces the amount of uncured monomers in EB-cured ink films, enabling faster press speeds and minimizing contamination risks in packaging applications, while ensuring compliance with migration limits, particularly in food packaging.

Implementation Method 1

Electron Beam (EB) curable compositions comprising alcohol containing substances

Methodology Applied
Scientific EffectElectron beam curing: Electron Beam

Implementation Method 2

compositions comprising ethylenically unsaturated monomers and oligomers

Methodology Applied
Scientific EffectFree radical polymerization: Photopolymerisation

Implementation Method 3

the inclusion of alcohols, and especially polyols... can promote the EB-curing of compositions comprising ethylenically unsaturated monomers and oligomers

Methodology Applied
Scientific EffectRadiation-induced radical formation: Radiation

Data Source

PatentUS11279838B2Electron beam curable compositions comprising polyols
Publication Date: 2022.03.22 SUN CHEMICAL CORP

AI summary

Electron beam curable compositions including polyols, and any blend of ethylenically unsaturated monomers and oligomers. The polyols of the invention are preferably essentially free of any ethylenically unsaturated groups, have greater than one hydroxy group and preferably have boiling points in excess of 170° C.