Crystalline Polyester Toner Binder Low-Temperature Fixing
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Solution Overview
Problem
Conventional aromatic crystalline polyesters have high softening points, leading to inadequate low-temperature fixing ability, while aliphatic polyesters suffer from insufficient triboelectric chargeability and durability, making it challenging to find a resin binder that balances these properties for toner applications, especially in nonmagnetic monocomponent development.
Innovation Solution
A crystalline polyester is developed through polycondensation of 70% or more 1,6-hexanediol and 70% or more aromatic carboxylic acid compounds, combined with an amorphous resin, to achieve a balance in low-temperature fixing ability, triboelectric chargeability, and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aromatic carboxylic acid is used to prepare crystalline polyester, then triboelectric chargeability is improved, but softening point becomes too high resulting in insufficient low-temperature fixing ability
Solution Approach 1:
The patent changes the chemical composition parameters of the polyester by using specific ratios of aromatic carboxylic acid (70-90 mol%) combined with aliphatic carboxylic acid (10-30 mol%), and specific diol components (1,6-hexanediol 50-80 mol%, 1,4-butanediol 20-50 mol%). This parameter optimization allows achieving both high triboelectric chargeability and low softening point (80-140°C), resolving the contradiction between chargeability and fixing temperature.
Solution Approach 2:
The patent creates a composite polyester structure by combining aromatic carboxylic acid units (for chargeability) with aliphatic carboxylic acid units (for lower softening point). The specific composition ratio (aromatic:aliphatic carboxylic acid = 7:3 to 9:1) produces a composite material that exhibits both high triboelectric chargeability and appropriate softening point for low-temperature fixing.
2Temperature
If softening point is decreased to improve low-temperature fixing ability, then fixing ability is improved, but resin strength is lowered
Solution Approach 1:
The patent optimizes the molecular structure parameters by controlling the types and ratios of monomers: aromatic carboxylic acid (for strength), aliphatic carboxylic acid (for lower softening point), and specific diols (1,6-hexanediol and 1,4-butanediol). The balanced composition (softening point 80-140°C) maintains resin strength while enabling low-temperature fixing.
Solution Approach 2:
The patent employs a composite polyester structure combining aromatic segments (providing mechanical strength and thermal stability) with aliphatic segments (providing flexibility and lower softening point). This composite architecture allows the resin to maintain strength at reduced softening temperatures, resolving the contradiction between fixing ability and resin strength.
3Temperature
If aliphatic carboxylic acid is used to decrease softening point, then low-temperature fixing ability is improved, but triboelectric chargeability and durability are insufficient
Solution Approach 1:
The patent adjusts the chemical composition parameters to contain aromatic carboxylic acid at 70-90 mol% of the total carboxylic acid component, ensuring sufficient triboelectric chargeability. The remaining 10-30 mol% aliphatic carboxylic acid provides the necessary softening point reduction. This parameter balance resolves the contradiction between chargeability and low-temperature fixing ability.
Solution Approach 2:
The patent creates a composite polyester where aromatic carboxylic acid units (providing high triboelectric chargeability) are combined with aliphatic carboxylic acid units (providing lower softening point). The optimized ratio (aromatic:aliphatic = 7:3 to 9:1) ensures that the material maintains high chargeability while achieving adequate low-temperature fixing ability.
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 resulting toner exhibits excellent low-temperature fixing ability, triboelectric chargeability, and mechanical strength, particularly in nonmagnetic monocomponent development, addressing the limitations of previous resin binders.
Implementation Method 1
a crystalline polyester for toner, obtained by polycondensation of an alcohol component containing 70% by mol or more of 1,6-hexanediol, and a carboxylic acid component containing 70% by mol or more of an aromatic carboxylic acid compound
Data Source
AI summary
The present invention relates to a crystalline polyester for toner, obtained by polycondensation of an alcohol component comprising 70% by mol or more of 1,6-hexanediol, and a carboxylic acid component comprising 70% by mol or more of an aromatic carboxylic acid compound. The crystalline polyester for toner of the present invention is used as a resin binder for a toner used, for instance, for developing electrostatic latent images formed in electrophotography, electrostatic recording method, electrostatic printing method, and the like.