Toner with Crystalline Polyester Domains for Fixing Width
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Solution Overview
Problem
Toner formulations face challenges in achieving both low-temperature fixability and hot offset resistance while maintaining a suitable fixing width, especially when used with thinner or smaller media, as existing methods either enhance low-temperature fixability at the expense of hot offset resistance or vice versa.
Innovation Solution
A toner composition is developed with crystalline polyester domains of specific size and distribution, where the number-average major diameter ranges from 50 nm to 300 nm, and the domains are dispersed across the toner such that at least 60% are present within 25% of the distance from the toner's outline to its centroid, enhancing both low-temperature fixability and hot offset resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the toner is made to be easily melt-deformable at low temperature to improve energy saving performance, then low-temperature fixability is improved, but the viscosity becomes too low at high temperature causing hot offset
Solution Approach 1:
The invention changes the physical and chemical parameters of the binder resin by specifying a glass transition temperature range of 40°C to 60°C and using specific resin compositions (styrene-acrylic copolymer with controlled soft and hard segments) to achieve optimal melt viscosity characteristics that improve low-temperature fixability while preventing hot offset
Solution Approach 2:
The invention uses a composite binder resin system combining styrene-acrylic copolymer with specific glass transition temperatures and other resin components to create a multi-component system that provides both low-temperature deformability and high-temperature stability, resolving the contradiction between easy fixing and hot offset resistance
2Temperature
If measures are taken to improve low-temperature fixability, then fixing width is maintained, but hot offset resistance deteriorates unless additional measures are taken
Solution Approach 1:
The invention optimizes the glass transition temperature parameter of the binder resin to fall within 40°C to 60°C, which controls the melting and deformation characteristics of the toner to achieve both low-temperature fixability and hot offset resistance within an enlarged fixing width
Solution Approach 2:
The invention creates local quality differences within the toner particle by controlling the distribution and characteristics of different resin components, particularly the soft and hard segments in the styrene-acrylic copolymer, to provide different functional properties in different regions of the toner structure
3Adaptability or versatility
If the toner is designed for adaptability to thinner and smaller media, then widespread use is improved, but the amount of heat received by the toner increases causing hot offset
Solution Approach 1:
The invention adjusts the thermal parameters of the toner, specifically the glass transition temperature and melting point characteristics of the binder resin, to enable the toner to be easily deformable at lower temperatures where less heat is available (thin/small media) while maintaining stability at higher temperatures to prevent hot offset
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
This approach effectively improves low-temperature fixability and suppresses hot offset, thereby enlarging the fixing width, ensuring the toner performs well across various media types and sizes.
Implementation Method 1
crystalline polyesters that can melt instantaneously at a melting point, thereby decreasing the melt viscosity of the toner
Implementation Method 2
the heat of the fixing unit is hardly absorbed by the media, the amount of heat received by the toner becomes larger than that in the case of thick media
Data Source
AI summary
Provided is a toner including a binder resin, a colorant, a crystalline polyester, and a release agent, wherein a cross-sectional image of the toner is observed using a scanning transmission electron microscope, domains of the crystalline polyester are present in the cross-sectional image of the toner, the domains have a number-average major diameter of at least 50 nm and not more than 300 nm, the number of the domains is at least 8 and not more than 500, and the domains are present at least 60 number % and not more than 100 number % from an outline of the cross-sectional image to 25% of the distance between the outline and the centroid of the cross-sectional image.