Toner Composition with Crystalline Polyester Resin for Heat Resistance
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Solution Overview
Problem
Toner particles using crystalline plasticizers face issues with heat resistance and low-temperature fixability, leading to adhesion defects in electrophotographic systems, particularly in double-sided printing where image defects are more common due to compatibility between the binder resin and plasticizer.
Innovation Solution
A toner composition with a controlled ratio of carbon atoms in the diol and dicarboxylic acid of the crystalline polyester resin, combined with an amorphous polyester resin having a linear alkyl group, promotes phase separation and recrystallization, enhancing heat resistance and low-temperature fixability while preventing adhesion of ejected paper.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a crystalline polyester resin is used as a plasticizer to achieve blocking resistance, then the toner can maintain particle separation in high-temperature environments, but the heat resistance of the fixed image deteriorates causing adhesion of ejected paper
Solution Approach 1:
The invention changes the chemical composition parameters of the crystalline polyester resin by controlling the carbon atom ratios of diol (COH) and dicarboxylic acid (CAc) components. Specifically, it uses a crystalline polyester resin where COH/CAc ≥ 3.5 and 0 ≤ |COH - CaPES| ≤ 3, where CaPES is the carbon atoms of the linear alkyl group. This parameter optimization allows the plasticizer to achieve appropriate phase separation for blocking resistance while maintaining sufficient diffusibility for heat resistance.
Solution Approach 2:
The invention creates local quality differences in the toner composition by using an amorphous polyester resin with a linear alkyl group at the molecular chain terminal as the binder resin. The linear alkyl group (8 ≤ CaPES ≤ 20) provides local hydrophobic character that promotes recrystallization of the crystalline plasticizer after fixing, improving heat resistance of the fixed image while maintaining low-temperature fixability.
2Reliability
If the compatibility between crystalline plasticizer and binder resin is lowered to improve heat resistance, then recrystallization is promoted, but the diffusibility of plasticizer into binder resin decreases causing deterioration of low-temperature fixability
Solution Approach 1:
The invention optimizes the chemical structure parameters of both the binder resin and crystalline plasticizer. The amorphous polyester resin contains a linear alkyl group with 8-20 carbon atoms, and the crystalline polyester resin satisfies COH/CAc ≥ 3.5 and 0 ≤ |COH - CaPES| ≤ 3. These parameter settings create optimal balance between compatibility and phase separation, enabling both heat resistance and low-temperature fixability.
3Temperature
If a high softening temperature polyester resin is used to improve blocking resistance, then toner particles resist fusing in high-temperature environments, but the low-temperature fixability of the toner is lowered
Solution Approach 1:
The invention uses a composite resin system consisting of an amorphous polyester resin as the main binder and a crystalline polyester resin as a plasticizer. The amorphous binder provides low-temperature fixability, while the crystalline plasticizer provides blocking resistance. This composite approach allows both contradictory requirements to be satisfied simultaneously.
Solution Approach 2:
The invention exploits phase transition properties of the crystalline polyester resin. The crystalline plasticizer undergoes phase transition at specific temperatures, providing sharp melt property that enables both blocking resistance at high temperatures and low-temperature fixability. The controlled composition ensures the phase transition occurs at optimal temperature points.
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 improved resistance to adhesion of ejected paper while maintaining low-temperature fixability and blocking resistance, ensuring high-quality image output even in high-temperature environments.
Implementation Method 1
it is possible to achieve appropriate phase separation property between the plasticizer and the binder resin
Implementation Method 2
it is possible to recrystallize the crystalline plasticizer after fixing and improve the heat resistance of the fixed image
Implementation Method 3
the number of carbon atoms of a linear alkyl group present at the end of the binder resin and the number of carbon atoms of the diol or dicarboxylic acid constituting the crystalline polyester resin are in a specific relationship. As a result, recrystallization of the crystalline polyester can be promoted.
Implementation Method 4
it is possible to achieve appropriate phase separation property between the plasticizer and the binder resin and diffusibility of the plasticizer in the binder resin
Data Source
AI summary
A toner comprising a toner particle including a binder resin and a crystalline polyester resin, wherein the binder resin is an amorphous polyester resin having a linear alkyl group at a molecular chain terminal; the crystalline polyester resin is a polycondensate of a diol and a dicarboxylic acid; the number of carbon atoms CaPES of the linear alkyl group, the number of carbon atoms COH of the diol, and the number of carbon atoms CAc of the dicarboxylic acid, excluding carbon that belongs to carboxyl groups, satisfy the following relationships; and a glass transition temperature of the toner as measured by a differential scanning calorimeter is from 40.0° C. to 55.0° C.8≤CaPES≤20 (1)CAc/COH≥3.5 and 0≤|CAc−CaPES|≤3 (2)COH/CAc≥3.5 and 0≤|COH−CaPES|≤3 (3)