Toner Composition with Composite Polyester Resins for Fixability
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Solution Overview
Problem
Current toners for high-speed printing lack sufficient low-temperature fixability and hot offset resistance, leading to image density fluctuations and fogging issues, especially after long-term printing.
Innovation Solution
A toner composition featuring a blend of polyester resins with different softening points, where one resin has a high softening point and the other a low softening point, both derived from aromatic diols, with specific polyhydric alcohol and polyvalent carboxylic acid units, ensuring uniform dispersion and improved stability through oxyalkylene ether and aliphatic dicarboxylic acid components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the glass transition point and softening point of the binder resin are reduced to achieve low-temperature fixability, then the fixability at low temperature is improved, but the hot offset resistance is reduced
Solution Approach 1:
The invention uses a composite binder resin system consisting of a polyester resin base and a polyether-modified polyester resin. The polyester resin provides hot offset resistance through its higher softening point, while the polyether-modified component contributes to low-temperature fixability by reducing the glass transition point. This composite structure allows simultaneous achievement of both low-temperature fixability and hot offset resistance that cannot be obtained with a single resin type.
Solution Approach 2:
The invention modifies the molecular structure parameters of the polyester resin by introducing polyether chains through modification. This changes the glass transition point and softening point parameters of the resin, enabling the material to exhibit both low-temperature flexibility and high-temperature stability. The specific parameter adjustment involves controlling the polyether content and molecular weight to optimize the balance between fixability and hot offset resistance.
2Reliability
If polyester resins with different softening points are used to achieve compatibility between low-temperature fixability and hot offset resistance, then both properties are improved to some level, but the fixability is insufficient for high-speed printing requiring about 100 sheets per minute
Solution Approach 1:
The invention optimizes the molecular weight and softening point parameters of the polyester resin to achieve rapid melting characteristics. By adjusting these parameters, the resin melts quickly at the fixing temperature, enabling high-speed printing. The specific parameter range is controlled to ensure both fast melting for high productivity and sufficient hot offset resistance.
3Productivity
If conventional toners are used for high-speed printing, then printing speed is maintained, but density fluctuation enlarges and fogging occurs in white portions after long-term printing
Solution Approach 1:
The invention employs a composite resin system that maintains toner particle integrity and uniformity during long-term high-speed printing. The combination of polyester resin and polyether-modified polyester resin prevents toner degradation, density fluctuation, and fogging by providing stable melting and solidification characteristics that preserve image quality over extended printing periods.
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 achieves enhanced low-temperature fixability and hot offset resistance, reducing image density fluctuations and fogging, even after prolonged printing, by maintaining the durability and stability of the toner particles.
Implementation Method 1
The glass transition point and softening point of the binder resin of the toner are reduced, and a binder resin having sharp-melt property is used
Implementation Method 2
The glass transition point and softening point of the binder resin of the toner are reduced
Implementation Method 3
the hot offset resistance of a toner that achieves low-temperature fixability is apt to reduce
Data Source
Figure 1
AI summary
Provided is a toner obtained by melting and kneading a binder resin containing a polyester resin A and a polyester resin B, a colorant, and a wax, in which in the resin A, the content of a polyhydric alcohol unit derived from an aromatic diol, the content of a polyhydric alcohol unit derived from an oxyalkylene ether of a novolac type phenol resin, and the content of a polyvalent carboxylic acid unit derived from an aliphatic dicarboxylic acid, which contains a straight-chain hydrocarbon having 4 or more to 16 or less carbon atoms as a main chain and has carboxyl groups at both of its terminals, fall within specific ranges, and in the resin B, the content of a polyhydric alcohol unit derived from an aromatic diol and the content of a polyvalent carboxylic acid unit derived from an aromatic dicarboxylic acid or a derivative thereof fall within specific ranges.