Actinic-Curable Offset Ink for Plastic Film Adhesion

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Solution Overview

Problem

Active energy ray-curable inks for offset printing face issues with curability, adhesiveness to plastic films, transferability, and hiding power, particularly due to high viscosity, volume shrinkage, and poor leveling properties, which lead to toning and hollow holes on printed surfaces.

Innovation Solution

The development of an active energy ray-curable ink formulation incorporating a pigment, polyfunctional (meth)acrylate with a hydroxyl group, and a resin with ethylenic unsaturated and hydrophilic groups, along with (meth)acrylates having alicyclic or aliphatic skeletons, to enhance dispersibility, cohesive force, and adhesiveness, while reducing viscosity and surface energy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If highly curable monomers with multiple reactive groups are used to improve curability, then curability is improved, but volume shrinkage during curing increases and adhesiveness to plastic film deteriorates

Engineering Contradiction:
ImprovecurabilityVSAvoidadhesiveness
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent changes the chemical structure parameters of the monomer from highly crosslinkable multi-functional monomers to monomers with hydroxyl groups and alicyclic/aliphatic structures. This parameter change reduces volume shrinkage during curing while maintaining curability through the reactive groups, thereby improving adhesiveness to plastic film substrates.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite ink formulation combining monomers with hydroxyl groups, alicyclic structures, and aliphatic structures. This composite approach balances curability (through reactive groups), reduces volume shrinkage (through specific molecular structures), and improves adhesiveness (through hydroxyl groups that can form hydrogen bonds with the substrate).

Inventive Principle:
Principle #40Composite materials

2Ease of operation

If ink viscosity is decreased to improve transferability and leveling properties, then transferability and leveling are improved, but cohesive force under high shearing stress deteriorates and toning occurs

Engineering Contradiction:
ImprovetransferabilityVSAvoidcohesive force
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The patent changes the viscosity parameter to an optimal range (50-200 cP) through careful selection of monomer molecular weight and structure. This parameter change improves transferability and leveling properties while maintaining sufficient cohesive force to prevent toning during the printing process.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by having different molecular weight components in the ink formulation. Lower molecular weight components provide low viscosity for good transferability, while higher molecular weight components provide cohesive strength to prevent toning, creating a multi-component system with differentiated functions.

Inventive Principle:
Principle #3Local quality

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 ink exhibits improved curability, toning resistance, transferability, and high hiding power, ensuring strong adhesion to plastic films and preventing hollow holes, thereby producing high-quality printed matter with reduced toning and improved mechanical properties.

Implementation Method 1

active energy ray-curable ink for offset printing (Patent Literature 1) combined with a specific photopolymerization initiators

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentEP3594293B1Actinic-ray-curable ink for lithographic printing and method for producing printed matter using same
Publication Date: 2024.02.21 TORAY INDUSTRIES INC

AI summary

Provided is active energy ray-curable ink for offset printing which has marked curability and toning resistance during printing, exhibits good transferability and adhesiveness to plastic films having low wettability, and imparts high hiding power to printed matter. The active energy ray-curable ink for offset printing includes a pigment, a polyfunctional (meth) acrylate having a hydroxyl group, and a resin having an ethylenic unsaturated group and a hydrophilic group.