Active Energy Ray Curable Ink Adhesion and Strength Balance

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Solution Overview

Problem

Active energy ray curable inks used in building materials face challenges in achieving a balance between strength and adhesion properties, especially when exposed to high temperatures, and existing solutions for improving adhesion require costly undercoating processes and specialized equipment.

Innovation Solution

A composition incorporating dicyclopentenyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, and polyfunctional polymerizable compounds that form a cured product with a glass transition temperature of 60°C or more and high adhesion to polycarbonate substrates, ensuring strength and adhesion simultaneously without the need for undercoating layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a monofunctional monomer with high glass transition temperature is used to achieve high hardness and strength, then strength is improved, but adhesion property deteriorates due to inner stress

Engineering Contradiction:
ImprovestrengthVSAvoidadhesion property
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The invention changes the chemical composition parameters of the polymerizable compound mixture, specifically incorporating monomers with different glass transition temperatures and molecular structures. This includes using monofunctional monomers (Tg: 80-120°C) combined with difunctional monomers (Tg: 50-90°C) in specific ratios, which modifies the physical and chemical properties of the cured coating to achieve both high strength and good adhesion simultaneously

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite polymer system by combining multiple polymerizable compounds with different functions and properties. The mixture includes monofunctional monomers for strength, difunctional monomers for adhesion and flexibility, and polyfunctional monomers for crosslinking density control. This composite approach allows the coating to exhibit both high strength and good adhesion properties that individual components cannot achieve alone

Inventive Principle:
Principle #40Composite materials

2Reliability

If an undercoat layer is applied to improve adhesion property, then adhesion property is improved, but device complexity and cost increase

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

Solution Approach 1:

The invention extracts and eliminates the unnecessary undercoat layer from the coating process. By reformulating the single-coat composition to include specific polymerizable compounds with adhesion-promoting properties, the patent removes the need for separate undercoating equipment and processes, thereby simplifying the overall system while maintaining or improving adhesion performance

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention makes the main coating composition universally functional by incorporating compounds that simultaneously provide adhesion, strength, and flexibility properties. The polymerizable compound mixture includes components that can perform multiple functions: bonding to substrates, forming strong cured networks, and providing flexibility. This multi-functional formulation eliminates the need for specialized undercoat layers, allowing a single coating to replace multiple layers

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

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 composition provides a cured product with enhanced strength and adhesion to polycarbonate substrates, maintaining integrity at elevated temperatures and eliminating the need for costly undercoating processes, thus offering a cost-effective solution for building materials.

Implementation Method 1

active energy ray curable composition includes a polymerizable compound composition comprising dicyclopentenyl acrylate... after a lapse of 15 seconds, the film is irradiated with an active energy ray

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentEP3118270B1Active energy ray curable composition, active energy ray curable ink, inkjet ink, inkjet recording method, two-dimensional or three-dimensional image forming apparatus, cured product, and processed product
Publication Date: 2021.09.01 RICOH CO LTD
  • EP3118270B1 patent drawingFigure 1A~1D
  • EP3118270B1 patent drawingFigure 2~3
  • EP3118270B1 patent drawingFigure 4~5

AI summary

In accordance with some embodiments of the present invention, an active energy ray curable composition including a polymerizable compound composition is provided. When the active energy ray curable composition is formed into a film having an average thickness of 10 µm on a substrate and, after a lapse of 15 seconds, the film is irradiated with an active energy ray having a light quantity of 1,500 mJ/cm2 to become a cured product, the cured product satisfies the following conditions (1) and (2): (1) when the substrate is a polypropylene substrate, the cured product has a glass transition temperature of 60°C or more; and (2) when the substrate is a polycarbonate substrate, an adhesion between the polycarbonate substrate and the cured product is 70 or more, the adhesion being measured according to a cross-cut adhesion test defined in Japanese Industrial Standards K5400.