Toner Matrix-Domain Structure for Low-Temperature Fixing
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Solution Overview
Problem
Toner fusion to the surface of photosensitive member drums in electrophotographic devices leads to image density non-uniformity, blank dots, and image smearing, especially in high-temperature, high-humidity environments during mass print output at high speeds, due to low-temperature fixability issues and viscosity drops.
Innovation Solution
A toner composition with a matrix-domain structure comprising a crystalline resin and amorphous resin, where the crystalline resin has specific monomer units and a wax is added, allowing for controlled viscoelasticity to prevent fusion, achieved through a melt-kneading and annealing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a crystalline resin is used as the main component of binder resin to achieve low-temperature fixability, then fixing performance at low temperature is improved, but toner strength at normal temperature deteriorates and fixed images become vulnerable to scraping and scratching
Solution Approach 1:
The patent uses a composite binder resin system comprising both crystalline resin and amorphous resin. The crystalline resin provides low-temperature fixability while the amorphous resin provides high-temperature strength and resistance to scraping and scratching. This composite approach allows the toner to exhibit both low-temperature fixability and high-temperature strength simultaneously.
2Productivity
If mass print output is performed at high speed in high-temperature, high-humidity environment, then productivity is improved, but toner viscosity drops and fusion to drum surface occurs
Solution Approach 1:
The patent modifies the viscoelastic properties of the binder resin by incorporating specific amorphous resin components and controlling the molecular weight distribution. This changes the temperature-dependent viscosity characteristics to maintain stable toner adhesion even at elevated temperatures and during high-speed operation, preventing fusion to the drum surface while maintaining productivity.
3Speed
If crystalline resin with sharp melt property is used to achieve faster toner melting, then fixing speed is improved, but toner exhibits low strength at normal temperature
Solution Approach 1:
The patent combines crystalline resin with sharp melt properties (for fast fixing) with amorphous resin (for high-temperature strength). The crystalline resin component provides rapid melting and fast fixing speed, while the amorphous resin component ensures high toner strength at normal and elevated temperatures, resolving the contradiction between fixing speed and strength.
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 toner exhibits excellent low-temperature fixability, preventing fusion to the drum and maintaining high-quality print output even in challenging environmental conditions, by controlling viscoelasticity and ensuring the toner does not adhere to the drum, thus enhancing productivity and image quality.
Implementation Method 1
the toner exhibits excellent low-temperature fixability, such that fusion of the toner to a drum can be suppressed, while delivering high-quality print articles
Implementation Method 2
a melt-kneading step of melt-kneading a mixture that contains the binder resin having the crystalline resin and the amorphous resin, and the wax
Implementation Method 3
an annealing step of holding a melt-kneaded product obtained after the melt-kneading step at a temperature of 40 to 60° C., for 30 minutes or longer
Data Source
AI summary
A toner comprises a toner particle that contains a binder resin having a crystalline resin and an amorphous resin, and a wax, wherein a matrix-domain structure made up of a matrix including the crystalline resin, and domains including the amorphous resin, is present in a cross-sectional observation of the toner, the crystalline resin has a specific monomer unit, in a differential curve, which is obtained through differentiation of a temperature-storage elastic modulus curve by temperature, with temperature being a horizontal axis and a common logarithm Log G′ of a storage elastic modulus G′ being a vertical axis as obtained in a viscoelasticity measurement of the toner, the differential curve has specific minimal values P1 and P2 within specific temperature ranges, and has storage elastic moduli G′ at the temperatures of the minimal values P1 and P2 lie in respective specific ranges.