Polyvinyl Alcohol Primer for Offset Media Inkjet Printing
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Solution Overview
Problem
Inkjet printing on offset media surfaces results in poor image quality, slow drying, and low durability due to hydrophobic and non-porous properties, which are not suitable for water-based inks, leading to issues like smearing and increased production costs.
Innovation Solution
A primer composition is applied to the media substrate, comprising polyvinyl alcohol with a weight average molecular weight of 50,000 to 250,000 Mw and a cationic salt, forming a complex structure that enhances wet film strength and instant dry smearfastness, allowing for high-speed printing without compromising print quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If offset coated paper with hydrophobic polymer coating is used for inkjet printing, then the media is suitable for conventional offset printing, but water-based inks exhibit poor image quality, slow drying, and poor durability
Solution Approach 1:
A primer coating is applied as an intermediary layer between the hydrophobic offset media and water-based inks. The primer contains hydrophilic polymers (polyvinyl alcohol, carboxymethyl cellulose) that attract and bind water-based inks, while also adhering to the offset coating. This mediator layer enables compatible interaction between incompatible materials.
Solution Approach 2:
The primer coating changes the surface properties of the offset media by introducing hydrophilic functional groups. The coating composition includes polymers with specific molecular weights and hydroxyl values that modify the surface energy and wettability, transforming the hydrophobic surface into a hydrophilic one suitable for water-based ink reception.
2Productivity
If conventional offset media is used for high-speed inkjet printing, then production speed can be maintained, but image quality and smear resistance deteriorate
Solution Approach 1:
The primer coating is applied in advance to the offset media before printing. This preliminary action prepares the surface to receive water-based inks properly, ensuring that when high-speed printing occurs, the inks are immediately absorbed and fixed by the primer layer, preventing smearing and maintaining image quality at high speeds.
3Ease of manufacture
If water-based inks are printed directly on offset media, then no additional coating process is needed, but drying time increases significantly and image durability decreases
Solution Approach 1:
The primer coating serves as a mediator that accelerates the drying process. Its hydrophilic polymer structure rapidly absorbs and binds water-based inks upon contact, enabling quick evaporation and fixation. This reduces drying time from over 24 hours to much shorter periods while maintaining a simple two-step process.
4Shape
If hydrophobic polymer coating is applied to paper for offset printing, then smooth non-porous surface is achieved, but water-based ink penetration and bonding are prevented
Solution Approach 1:
The primer coating introduces local hydrophilic quality to specific regions of the offset media surface. By applying the primer in controlled amounts (0.1-10 gsm), it creates localized zones of enhanced ink receptivity without compromising the overall smooth surface quality needed for high-quality printing.
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 primer composition improves the interaction of water-based inks with offset media, ensuring instant dry and wet smearfastness, preventing image smearing and allowing high-speed printing without additional drying time, thus maintaining print quality and reducing production costs.
Implementation Method 1
comprising polyvinyl alcohol with a weight average molecular weight of 50,000 to 250,000 Mw and a cationic salt, forming a complex structure that enhances wet film strength
Implementation Method 2
The primer compositions can be applied to a substrate to form an ink-receiving layer on the substrate before printing inkjet ink over or onto the primer layer
Data Source
AI summary
The present disclosure is drawn to primer compositions, which can include a polyvinyl alcohol, a cationic salt, and water. The polyvinyl alcohol can have a weight average molecular weight from about 50,000 Mw to about 250,000 Mw. The cationic salt can be present in an amount of at least 15 wt % of all dry components of the primer composition. The polyvinyl alcohol and cationic salt together can make up at least 30 wt % of all dry components of the primer composition.