Photocurable Ink Adhesion on Polycarbonate via Delayed Curing
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Solution Overview
Problem
Existing printing technologies using photocurable ink on high chemical resistance printing media, such as polycarbonate, face issues with weak adhesive force between the ink and the medium, leading to potential damage during processing and expansion of the medium.
Innovation Solution
A printing method involving a layered structure where the first photocurable ink layer is cured after at least three seconds of irradiation, forming a compatible layer with the medium, followed by additional ink layers, to enhance adhesive force and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ultraviolet ray light source is arranged neighboring the recording head and moves integrally with the recording head, then productivity is improved due to short curing time, but adhesive force deteriorates because compatible layer is not sufficiently formed
Solution Approach 1:
The patent segments the printing process into distinct stages: a first recording head applies a first photocurable ink layer that is NOT immediately cured, allowing a compatible layer to form; then a second recording head applies additional ink layers which ARE cured by an ultraviolet ray light source. This segmentation separates the compatible layer formation process from the curing process, resolving the contradiction between productivity and adhesive force.
Solution Approach 2:
The patent applies preliminary action by first forming the compatible layer through the first photocurable ink layer before applying and curing the remaining ink layers. The first ink layer is applied and allowed to intermix with the printing medium surface to create the compatible layer, and only after this preliminary action is complete are the subsequent layers cured with ultraviolet rays. This ensures strong adhesion while maintaining efficient processing.
2Productivity
If curing is performed immediately after ink discharge, then productivity is improved, but reliability deteriorates due to weak adhesive force causing ink layer damage during processing
Solution Approach 1:
The patent divides the ink application into two segments: a first photocurable ink layer applied by a first recording head that serves as an adhesive promoter and is NOT cured immediately, and subsequent ink layers applied by a second recording head that ARE cured by ultraviolet rays. This segmentation allows the first layer to reliably bond with the medium while maintaining high processing efficiency through immediate curing of the image-forming layers.
Solution Approach 2:
The first photocurable ink layer acts as an intermediary between the printing medium and the subsequent ink layers. It is applied and allowed to form a compatible layer with the medium surface, creating a reliable bonding interface. The ultraviolet ray light source then cures the subsequent layers, which are now firmly anchored to the medium through this intermediary layer, ensuring ink layer stability during processing.
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 significantly increases the adhesive force of the ink to the printing medium, ensuring the image is stably supported and preventing damage during processing and expansion of the medium.
Implementation Method 1
a photocurable ink is discharged from the recording head onto a printing medium while the carriage moves in the main scanning direction, thereby forming an image and the image is cured while being irradiated with light from the ultraviolet ray light source
Data Source
AI summary
A printing apparatus that prints an image while forming a layered body, which has a layered structure in which a plurality of ink layers formed by applying a photocurable ink is layered and at least a portion of the plurality of ink layers is an image layer, on a printing medium, is provided with a first ink layer forming section that coats a printing medium with a first photocurable ink that configures a lowermost layer of the plurality of ink layers to form the lowermost layer, and causes the lowermost layer to be cured while irradiating the lowermost layer with light after at least three seconds elapse; and a second ink layer forming section that applies an ink layer other than the lowermost layer after the first photocurable ink is cured.