Plastic Substrate Deinking Composition for Peeling Cured Ink Layers

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Solution Overview

Problem

Existing methods struggle to effectively peel off ink layers from plastic substrates, particularly those with complex configurations or multiple layers, leading to difficulties in recycling and deteriorating the quality of recycled plastics.

Innovation Solution

A deinking method using a deinking agent composed of 20% or more water-soluble solvent and 0.1% to 10% inorganic base, such as sodium hydroxide, facilitates the removal of ink layers from plastic substrates, including those with cured ink films and laminated structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If high-acid-value resin ink is used to peel off ink from plastic substrate with alkaline solution, then ink removal is achieved, but a large amount of alkaline solution is required due to neutralization

Engineering Contradiction:

Improveamount of alkaline solutionVSAvoidcost of deinking process

Core Design Contradiction:

Quantity of substanceVSEase of manufacture

Solution Approach 1:

The patent changes the chemical parameters of the deinking agent by incorporating specific surfactants and organic solvents alongside the alkaline solution. This modifies the mechanism of ink removal from purely alkaline neutralization to a combined surfactant-alkaline action, reducing the amount of alkaline solution needed while maintaining effective ink removal.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The deinking agent is formulated as a composite solution containing multiple components: alkaline solution, surfactants, and organic solvents. This composite approach allows each component to contribute differently to the ink removal process, reducing reliance on large quantities of alkaline solution alone and improving overall deinking efficiency.

Inventive Principle:

Principle #40Composite materials

2Strength

If thermosetting type ink is used on plastic substrate, then adhesion and designability are improved, but peeling of ink film becomes more difficult

Engineering Contradiction:

Improveadhesion of ink to substrateVSAvoiddifficulty of peeling ink film

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The surfactant acts as an intermediary substance that penetrates between the thermosetting ink film and the plastic substrate. It reduces the interfacial adhesion forces, allowing the strongly adhered thermosetting ink to be peeled off without requiring excessive mechanical force or damaging the substrate.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces purely mechanical peeling methods with a chemical approach using surfactants and organic solvents. Instead of relying on mechanical force to separate the strongly adhered thermosetting ink, the chemical agents soften and loosen the ink film, making peeling easier and more efficient.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If multilayer ink layers are formed to increase designability, then print quality is improved, but peeling process becomes more complex and difficult

Engineering Contradiction:

Improveprint quality and designabilityVSAvoidcomplexity of peeling process

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The deinking agent is designed with universal applicability to handle multiple types of ink layers simultaneously. The combination of surfactants and organic solvents creates a multi-functional solution that can penetrate and loosen different ink formulations (thermoplastic, thermosetting, solvent-based, water-based) in a single treatment step, simplifying the peeling process for multilayer printed substrates.

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 method enables easy and efficient removal of ink layers from various plastic substrates, improving the quality of recycled plastics by ensuring they are free from ink adhesion and allowing for high-quality recovery.

Implementation Method 1

a deinking agent that contains (a) 20 mass % or more of a water-soluble solvent and (b) 0.1 mass % to 10 mass % of an inorganic base

Methodology Applied

Scientific EffectDissolution: Solvation

Implementation Method 2

the ink layer by using a deinking agent that contains (a) 20 mass % or more of a water-soluble solvent and (b) 0.1 mass % to 10 mass % of an inorganic base

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Data Source

PatentUS12503613B2Deinking method, deinking agent for use in said deinking method, and plastic substrate recovery method using same

Publication Date: 2025.12.23 DIC CORP

AI summary

The invention provides a deinking method including a step of peeling off and removing, from a plastic substrate having an ink layer, the ink layer by using a deinking agent that contains (a) 20 mass % or more of a water-soluble solvent and (b) 0.1 mass % to 10 mass % of an inorganic base. According to the invention, it is possible to provide a deinking method that can easily peel off an ink layer printed on a plastic substrate, a deinking agent that can be used in the deinking method, and a plastic substrate recovery method using the same.