Crystalline Polyester Resin for Toner Fixing
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Solution Overview
Problem
Current toners fail to simultaneously achieve low-temperature fixability, hot offset resistance, image gloss, and storability, as existing crystalline polyester resins are difficult to pulverize, have low yields, and lack sufficient hot offset resistance and electrostatic properties.
Innovation Solution
A crystalline polyester resin is developed through condensation polymerization of a mixture with a C8-12 aliphatic dicarboxylic acid and diol, with a specific ratio of carboxyl and hydroxyl groups, achieving excellent low-temperature fixability, hot offset resistance, and image gloss, and is used in a binder resin dispersion for toner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If crystalline polyester resin is used as binder resin to achieve low-temperature fixability and storability, then fixing temperature can be lowered and storability improved, but hot offset resistance becomes insufficient and productivity decreases due to difficulty in pulverization
Solution Approach 1:
The patent changes the chemical composition parameters of the crystalline polyester resin by specifying the use of C8-12 aliphatic dicarboxylic acid and C8-12 aliphatic diol with specific molecular weights and structures. This parameter optimization enables the resin to have improved pulverization characteristics while maintaining low-temperature fixability and hot offset resistance
Solution Approach 2:
The patent creates a composite binder resin system by combining crystalline polyester resin with specific amorphous polyester resin in defined weight ratios (crystalline: 30-70 wt%, amorphous: 30-70 wt%). This composite structure synergistically improves both pulverization efficiency and hot offset resistance while maintaining low-temperature fixability
2Stability of the object's composition
If crystalline polyester resin content is increased to improve storability and low-temperature fixability, then glass transition point is maintained higher, but hot offset resistance deteriorates due to deep toner penetration into paper
Solution Approach 1:
The patent optimizes the molecular weight parameters of both crystalline and amorphous polyester resins. The crystalline polyester has weight-average molecular weight of 5,000-15,000 and the amorphous polyester has weight-average molecular weight of 10,000-30,000. This parameter control prevents excessive melting and deep penetration into paper, thereby improving hot offset resistance while maintaining storability
Solution Approach 2:
The patent employs a composite binder resin system where amorphous polyester resin acts as a matrix and crystalline polyester resin provides structural stability. The amorphous component controls melting behavior and penetration depth, while the crystalline component maintains high-temperature resistance and storability, achieving synergistic effect
3Temperature
If conventional crystalline polyester resin is used to achieve low-temperature fixability, then fixing temperature can be reduced, but electrostatic properties become insufficient due to resin structure
Solution Approach 1:
The patent combines crystalline polyester resin with amorphous polyester resin that has specific glass transition point (40-80°C). The amorphous component contributes to electrostatic charge retention and electrification properties, while the crystalline component provides low-temperature fixability. This composite structure achieves both low-temperature fixability and sufficient electrostatic properties
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 crystalline polyester resin enables the production of toners with improved low-temperature fixability, hot offset resistance, and image gloss, while maintaining storability and electrostatic properties, addressing the limitations of previous toner technologies.
Implementation Method 1
A crystalline polyester resin is developed through condensation polymerization of a mixture with a C8-12 aliphatic dicarboxylic acid and diol, with a specific ratio of carboxyl and hydroxyl groups
Data Source
Figure 1
AI summary
The invention provides a crystalline polyester resin obtained by condensation polymerization of a mixture comprising a polycarboxylic acid component and a polyol component, present in a range such that the ratio of the number of carboxyl groups from the polycarboxylic acid component and the number of hydroxyl groups from the polyol component is in the range of 100:108 to 100:120, and having an acid value of 5 to 20 mgKOH/g, wherein the polycarboxylic acid component includes a C8-12 aliphatic dicarboxylic acid, the content ratio of carboxyl groups from the C8-12 aliphatic dicarboxylic acid is at least 90 mol% of the total amount of carboxyl groups from the polycarboxylic acid component, the polyol component includes a C8-12 aliphatic diol, and the content ratio of hydroxyl groups from the C8-12 aliphatic diol is at least 90 mol% of the total amount of hydroxyl groups from the polyol component.