Intermediate Drying Units for Non-Polar Plastic Foil Inkjet Printing

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Solution Overview

Problem

Existing printing processes for water-soluble inks on non-polar plastic foils are inefficient and incomplete, requiring complex drying processes that often result in incomplete drying and color bleeding.

Innovation Solution

A system with multiple intermediate drying units, each subordinate to a corresponding print unit, is used to partially dry the pressure medium, increasing viscosity and preventing color bleeding by forming a skin on the ink droplets.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single intermediate drying unit is used after each printing unit, then the drying process is simplified, but the drying completeness is insufficient leading to color bleeding

Engineering Contradiction:
Improvedrying system complexityVSAvoiddrying completeness
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The intermediate drying unit is divided into multiple drying zones (first, second, and third drying zones) arranged in sequence. Each zone contains drying elements that work together to progressively remove solvent from the printed material, achieving complete drying and preventing color bleeding while maintaining system simplicity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The drying system transitions from a single-point drying approach to a distributed multi-zone drying approach along the material transport path. This spatial distribution of drying zones ensures thorough solvent removal without requiring complex individual drying units at each printing position.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If multiple intermediate drying units are used after each printing unit, then drying completeness improves, but the device complexity increases

Engineering Contradiction:
Improvedrying completenessVSAvoiddrying system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

Multiple drying zones are merged into a single integrated intermediate drying unit that processes the material continuously. This consolidation achieves the drying completeness of multiple separate units while avoiding the operational complexity of managing multiple independent drying systems after each printing unit.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The intermediate drying unit with multiple zones serves as a universal drying solution that can handle various printing configurations (single or multiple printing units). This multi-functional design provides complete drying capability without requiring separate specialized drying units for each printing position.

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

3Productivity

If conventional drying methods are used, then the process is simple, but the drying time is too long affecting productivity

Engineering Contradiction:
Improvedrying speedVSAvoiddrying time
Core Design Contradiction:
ProductivityVSDuration of action of moving object

Solution Approach 1:

The intermediate drying unit provides continuous drying action through multiple sequential zones that continuously remove solvent from the printed material as it passes through. This continuous multi-zone drying process significantly reduces drying time compared to conventional single-stage methods, thereby improving productivity without requiring complex intermittent drying cycles.

Inventive Principle:
Principle #20Continuity of useful action

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 enables more efficient and complete intermediate drying on non-absorbing surfaces, improving the printing result by preventing color bleeding and ensuring better adhesion of the ink to the plastic foil.

Implementation Method 1

a first intermediate drying unit, which is arranged downstream of a first printing unit and is configured to at least partially dry a first printing fluid discharged by the first printing unit on a surface of a printing medium

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 2

EP 2 644 391 A1 discloses a printing system with a plurality of inkjet printing units, each of which is followed by infrared drying units

Methodology Applied
Scientific EffectInfrared radiation: Infrared Radiation

Implementation Method 3

A printing system in which a plurality of inkjet printing units are used, followed by microwave heating devices, is known from the publication EP 1 738 916 A1

Methodology Applied
Scientific EffectMicrowave heating: Microwave Radiation

Data Source

PatentEP3921173B1System and process for intermediate drying of a printed material
Publication Date: 2025.04.16 WINDMOELLER & HOELSCHER GMBH
  • EP3921173B1 patent drawingFigure 1
  • EP3921173B1 patent drawingFigure 2
  • EP3921173B1 patent drawingFigure 3

AI summary

A system for intermediate drying of a printing medium, comprising: a first intermediate drying unit arranged downstream of a first printing unit and designed to at least partially dry a first printing liquid discharged from the first printing unit on a surface of a printing medium; and a second intermediate drying unit arranged downstream of a second printing unit, different from the first printing unit, and designed to at least partially dry a second printing liquid discharged from the second printing unit on the surface of the printing medium.