UV Curable Ink Adhesion to Non-Porous Substrates
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Solution Overview
Problem
UV curable inks face challenges with adhesion to non-porous or low surface tension substrates like polypropylene and exhibit high viscosity, leading to difficulties in jetting and slower printing speeds, as well as reduced cohesion between ink layers.
Innovation Solution
A photo-curable ink composition comprising a liquid vehicle, milled pigment, photo initiator, and halogenated polyolefin, suitable for use with UV, IR, or visible light energy, which improves adhesion to non-porous substrates and allows for higher jetting frequencies without air removal, using solvents like triethyleneglycol divinyl ether to minimize gas content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If UV curable inks are used to achieve fast drying and solidification, then printing speed is improved, but adhesion to non-porous substrates deteriorates
Solution Approach 1:
The patent introduces a silane coupling agent as an intermediary substance that bridges the ink and the non-porous substrate. The silane modifies the substrate surface to create a more reactive interface, enabling better adhesion between the UV curable ink and the substrate without compromising the fast curing speed.
Solution Approach 2:
The patent changes the chemical parameters of the ink formulation by incorporating silane-modified oligomers and specific photoinitiators. This modifies the surface energy and chemical reactivity of the ink, allowing it to adhere better to non-porous substrates while maintaining fast UV curing performance.
2Productivity
If UV curable inks are used to achieve rapid solidification, then production efficiency is improved, but viscosity becomes too high for proper jetting
Solution Approach 1:
The patent adjusts the viscosity parameters of the ink by selecting appropriate oligomer molecular weights and adding viscosity control agents. The ink formulation is optimized to maintain low enough viscosity for reliable jetting while containing sufficient solidifying components for fast UV curing.
Solution Approach 2:
The patent creates a dynamic viscosity profile where the ink maintains low viscosity during jetting (for ease of operation) but rapidly increases viscosity upon UV exposure (for fast solidification). This is achieved through the selection of photoinitiators that trigger rapid polymerization upon contact with UV light.
3Ease of operation
If UV curable inks are jetted at elevated temperatures to control viscosity, then jetting is improved, but print head life deteriorates
Solution Approach 1:
The patent changes the temperature parameter by formulating the ink to jet at lower temperatures (below 40°C) while using silane coupling agents and modified oligomers to compensate for the reduced thermal energy. This eliminates the need for elevated temperatures during jetting, protecting the print head from thermal damage.
Solution Approach 2:
The silane coupling agent acts as a mediator that enables proper ink flow and adhesion at lower temperatures. The silane-modified oligomers provide sufficient reactivity and adhesion properties even when jetted at reduced temperatures, eliminating the need to heat the ink to maintain jetting performance.
4Ease of manufacture
If conventional inks are used on non-porous substrates, then printing process is simple, but adhesion remains poor due to low surface tension
Solution Approach 1:
The silane coupling agent serves as a chemical intermediary that bridges the gap between conventional ink formulations and non-porous substrates. The silane modifies the substrate surface to create a more reactive interface, enabling better adhesion without requiring complex printing process changes.
Solution Approach 2:
The patent changes the surface energy parameters of the substrate through silane treatment. This increases the surface tension and reactivity of the non-porous substrate, allowing conventional UV curable inks to adhere properly without modifying the ink formulation or printing process significantly.
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 ink composition achieves improved adhesion to non-porous substrates, reduces ink viscosity, and enables higher printing speeds with reduced gas content, minimizing ink reactivity and extending print head life.
Implementation Method 1
curing of ink by radiation, and in particular ultraviolet (UV) curing... The term 'curing' in the context of the present application refers to a process of converting a liquid, such as ink, into a solid by exposure to actinic radiation
Data Source
AI summary
The present invention is drawn to photo-curable ink-jet ink compositions, systems, and methods. One exemplary ink-jet ink composition includes a liquid vehicle, a milled pigment, a photo initiator and a halogenated polyolefin. In this embodiment, the addition of the halogenated polyolefin improves adhesion to a non-porous substrate or a low surface tension substrate such as polypropylene.