Digital Printing Ink Chemical Bonding for Resin Adhesion

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Solution Overview

Problem

Existing digital printing methods for producing flat or web-like workpieces, such as kitchen countertops or decorative laminates, face challenges in achieving sufficient adhesion between printed layers and the underlying material, leading to insufficient ink retention and reduced optical brilliance due to physical rather than chemical bonding between the ink and resin.

Innovation Solution

The method employs acrylate-based inks with crosslinkers that form a chemical bond with melamine or phenolic resin mixtures during a thermal pressing process, ensuring improved adhesion and higher ink retention, using a digital inkjet printing process with a crosslinker that reacts above 50°C and a radiation-curing ink with photoinitiators for partial curing, followed by impregnation and curing in a heating press.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If physical adhesion between ink and resin is used, then manufacturing process is simple, but adhesion strength is insufficient

Engineering Contradiction:
Improveadhesion strengthVSAvoidprocess complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent changes the chemical parameters of the ink by incorporating functional groups (isocyanate, hydroxyl, carboxyl, amino, or epoxy groups) that can chemically react with the resin. This transforms the adhesion mechanism from physical to chemical bonding, significantly improving adhesion strength while maintaining process simplicity.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite ink system combining acrylate polymers with reactive functional groups that can form chemical bonds with the resin matrix. This composite approach enables both strong chemical adhesion and compatibility with the existing resin impregnation process.

Inventive Principle:
Principle #40Composite materials

2Illumination intensity

If high ink application is used, then color brilliance is improved, but adhesion between ink and resin deteriorates

Engineering Contradiction:
Improveoptical brillianceVSAvoidadhesion strength
Core Design Contradiction:
Illumination intensityVSStrength

Solution Approach 1:

By changing the chemical composition of the ink to include reactive functional groups, the patent enables high ink application (up to 10 g/m² or more) without adhesion failure. The chemical bonding capability allows the ink to maintain strong attachment to the resin even at higher concentrations and thicker applications.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If ink droplets are positioned deep in the workpiece, then ink retention is improved, but optical brilliance deteriorates

Engineering Contradiction:
Improveink retentionVSAvoidoptical brilliance
Core Design Contradiction:
ReliabilityVSIllumination intensity

Solution Approach 1:

The patent uses the reactive functional groups in the ink as intermediaries that create chemical bonds between the ink droplets and the resin matrix. This chemical anchoring allows ink droplets to remain securely positioned near the surface (within 0.1-10 µm depth) without sinking deeper, maintaining both retention and optical brilliance.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

This approach enhances the adhesion and durability of the printed surface, allowing for higher ink application and producing a more brilliant, high-quality image with a firm chemical bond between the ink and resin, surpassing the limitations of physical adhesion in prior methods.

Implementation Method 1

A crosslinker is used as an additional additive in this acrylate-containing printing ink, which, when thermally activated, produces a chemical bond between the acrylate-containing printing ink and the resin mixture used for impregnation

Methodology Applied
Scientific EffectChemical bonding: Chemical Bonding

Implementation Method 2

The crosslinker only enters into a chemical bond with both the acrylate compound and the resin compound during a pressing process in a hot press

Methodology Applied
Scientific EffectThermal activation: Heating

Implementation Method 3

a radiation-curing ink with photoinitiators for partial curing

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Implementation Method 4

subsequent curing of the melamine resin (condensation reaction)

Methodology Applied
Scientific EffectCondensation reaction: Condensation

Data Source

PatentEP2431190B1Method for manufacturing a digitally printed workpiece
Publication Date: 2013.09.11 THEODOR HYMMEN HLDG
  • EP2431190B1 patent drawingFigure 1
  • EP2431190B1 patent drawingFigure 2
  • EP2431190B1 patent drawingFigure 3~4

AI summary

The method involves providing a digital data set for a digital print device (1). A workpiece (20) is supplied to the print device. The workpiece is digitally printed by the printing device using acrylate containing printing color. A supplied resin mixture (5) and/or the color is contained with chemical binder as a component. The binder forms a chemical composition between polymerization acrylate of the color and the mixture in a heating press (7). The mixture is hardened by the press by simultaneous chemical reaction of the binder with the acrylate of the color and the mixture.