Aqueous Primer Coating Composition for High-Speed Digital Printing
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Solution Overview
Problem
High-speed digital printing presses require primers that enhance liquid toner transfer and adhesion to substrates while maintaining water resistance, as existing primers fail to perform effectively at higher speeds and exhibit poor water resistance.
Innovation Solution
An aqueous primer coating composition comprising cationic polyurethane and polymer oxazoline or N-vinylpyrrolidone, which provides superior toner transfer and adhesion, and includes a wetting agent, defoamer, surfactant, biocide, and pH adjuster to ensure effective coating on various substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing primers are used on substrates for high-speed digital printing presses, then liquid toner transfer and adhesion are improved, but water resistance deteriorates
Solution Approach 1:
The patent uses a composite primer composition comprising a polyurethane polymer and a polyester polymer with specific functional groups. This composite material combines the adhesion properties of polyurethane with the water resistance and reactivity of polyester, achieving both good liquid toner transfer/adhesion and water resistance simultaneously
Solution Approach 2:
The patent specifies precise parameter ranges for the polymer components including molecular weight (5,000-50,000 g/mol), functional group content (0.5-5 mmol/g), and composition ratios (70-95% polyurethane, 5-30% polyester). These parameter optimizations enable the primer to achieve both high-speed printing performance and water resistance
2Productivity
If activation temperature is reduced for high-speed printing, then toner transfer speed is improved, but primer effectiveness deteriorates
Solution Approach 1:
The patent lowers the activation temperature parameter to 50-150°C (optimally 70-120°C) while maintaining primer effectiveness through the use of polyester polymers with carboxyl or hydroxyl groups that react at these reduced temperatures, enabling high-speed printing without sacrificing toner transfer quality
Solution Approach 2:
The primer composition includes specific functional groups (carboxyl, hydroxyl) at controlled concentrations (0.5-5 mmol/g) that create localized reactive sites on the substrate surface, enabling effective toner adhesion at lower activation temperatures required for high-speed 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 coating composition achieves excellent liquid toner transfer and adhesion, maintains non-blocking properties, and provides enhanced water resistance, suitable for high-speed digital presses like the HP Indigo WS 6000 series, without the need for additional coatings.
Implementation Method 1
enhance their adhesion to a substrate
Implementation Method 2
includes a wetting agent
Data Source
AI summary
An aqueous primer coating composition to a substrate comprises an aqueous cationic polyurethane and an aqueous polymer of oxazoline or N-vinylpyrrolidone. Also disclosed is a method applying the coating composition to the substrate and an electrophotographical printing medium coated with the coating composition.