Liquid Developer Toner Crystalline Resin Offset Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Liquid developers with low-temperature fixability often suffer from high-temperature offset and document offset issues, where toner adheres to fixation rollers and softens, leading to contamination and color transfer, respectively, compromising gloss and fixation strength.
Innovation Solution
A liquid developer with toner particles containing a crystalline urethane-modified polyester resin, which has a peak in differential scanning calorimetry (DSC) curves at specific temperatures and a storage elastic modulus within certain ranges, preventing toner melting and ensuring elasticity at high temperatures, thereby preventing offset and maintaining moderate gloss and fixation strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a liquid developer excellent in low-temperature fixability is employed, then low-temperature fixability is improved, but high-temperature offset occurs due to toner adhering to fixation roller
Solution Approach 1:
The invention changes the physical and chemical parameters of the toner particles by controlling the crystallinity of the polyester resin and adjusting the molecular weight of the resin component. Specifically, the toner particles are designed with a crystalline polyester resin having a melting point of 60°C or higher and a number-average molecular weight of 10,000 to 50,000, which modifies the toner's thermal behavior to prevent adhesion at high temperatures while maintaining low-temperature fixability.
Solution Approach 2:
The invention uses a composite material system consisting of crystalline polyester resin combined with other resin components (such as amorphous polyester resin or polyurethane resin) to create toner particles with optimized thermal properties. This composite approach allows the toner to exhibit both low-temperature fixability and high-temperature stability, resolving the contradiction between these two requirements.
2Temperature
If a liquid developer excellent in low-temperature fixability is employed, then low-temperature fixability is improved, but document offset occurs when printed matter is stored in high-temperature or pressurized condition
Solution Approach 1:
The invention modifies the thermal parameters of the toner particles by selecting a crystalline polyester resin with a melting point of 60°C or higher and controlling its number-average molecular weight to be 10,000 to 50,000. These parameter changes ensure that the toner maintains its structural integrity under high-temperature storage conditions, preventing color transfer and document offset while preserving low-temperature fixability.
Solution Approach 2:
The invention applies beforehand cushioning by designing toner particles with enhanced thermal stability through the use of crystalline polyester resin with controlled molecular weight and melting point. This pre-engineered thermal resistance acts as a cushion against future high-temperature storage conditions, preventing document offset before it can occur.
3Strength
If toner particles are softened to ensure fixation strength, then fixation strength is improved, but gloss becomes uncontrolled and offset increases
Solution Approach 1:
The invention precisely controls the softening behavior of toner particles by selecting a crystalline polyester resin with a melting point of 60°C or higher and a number-average molecular weight of 10,000 to 50,000. This controlled softening ensures sufficient fixation strength while preventing excessive gloss and offset, as the toner softens just enough to bond to the substrate without becoming overly fluid.
Solution Approach 2:
The invention applies local quality by creating toner particles with a core-shell structure or heterogeneous composition where the crystalline polyester resin provides controlled softening for fixation strength, while other components maintain structural integrity and control gloss. This localized functional differentiation allows simultaneous achievement of fixation strength and offset prevention.
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 solution effectively prevents high-temperature offset and document offset while ensuring moderate gloss and fixation strength, as confirmed by experiments where images remained intact under high temperature and pressure conditions without contamination or damage.
Implementation Method 1
The toner particles have a peak in a differential scanning calorimetry (DSC) curve in temperature increase at 55° C. or higher, have a peak in the DSC curve in temperature decrease at 30° C. or higher
Implementation Method 2
When a liquid developer excellent in low-temperature fixability is employed, molten toner tends to adhere to a fixation roller during fixation
Implementation Method 3
The resin contains a crystalline urethane-modified polyester resin resulting from increase in chain length of a component derived from a polyester resin
Implementation Method 4
have a storage elastic modulus at 80° C., not lower than 1×105 Pa and not higher than 1×107 Pa
Data Source
AI summary
A liquid developer includes an insulating liquid and toner particles which are dispersed in the insulating liquid and contain a resin and a coloring agent. The resin contains a first resin which is a crystalline urethane-modified polyester resin resulting from increase in chain length of a component derived from a polyester resin by a compound containing an isocyanate group. The toner particles have a peak in a DSC curve in temperature increase at 55° C. or higher, have a peak in the DSC curve in temperature decrease at 30° C. or higher, and have a storage elastic modulus at 80° C., not lower than 1×105 Pa and not higher than 1×107 Pa.