Crystalline-Amorphous Polyester Toner for Low-Temperature Fixing
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Solution Overview
Problem
Toner formulations with crystalline and amorphous resins face challenges in achieving low-temperature fixing ability while maintaining high-temperature offset resistance, storage stability, and preventing uneven line formation on developer rollers, especially in nonmagnetic monocomponent developing devices.
Innovation Solution
A toner composition with a resin binder comprising a crystalline polyester and an amorphous resin, where the crystalline polyester is obtained by polycondensing an aliphatic diol and aromatic dicarboxylic or tricarboxylic acid compounds, with a weight-average molecular weight of 20,000 to 150,000, and a weight ratio of crystalline to amorphous resin of 55/45 to 95/5, enhancing low-temperature fixing and high-temperature offset resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a crystalline polyester with low softening point is used to achieve low-temperature fixing ability, then fixing temperature is reduced, but high-temperature offset resistance deteriorates
Solution Approach 1:
The invention uses a composite resin binder system comprising both crystalline polyester and amorphous polyester resins. The crystalline polyester (5-50 wt%) provides low-temperature fixing ability through its low softening point (85-150°C), while the amorphous polyester (50-95 wt%) with glass transition temperature of 40-80°C maintains high-temperature offset resistance. This composite approach allows simultaneous achievement of both low fixing temperature and high offset resistance that cannot be obtained with single resin systems.
Solution Approach 2:
The invention optimizes specific parameters of the crystalline polyester including softening point (85-150°C), weight-average molecular weight (20,000-150,000), and crystallinity (30-80%). By precisely controlling these parameters along with the resin composition ratio and amorphous polyester glass transition temperature, the toner achieves optimal balance between low-temperature fixing ability and high-temperature offset resistance.
2Temperature
If the content of crystalline polyester is increased to improve low-temperature fixing ability, then fixing temperature is reduced, but storage stability deteriorates
Solution Approach 1:
The invention identifies and controls critical parameters including crystalline polyester content (5-50 wt%), softening point (85-150°C), weight-average molecular weight (20,000-150,000), and crystallinity (30-80%). By optimizing these parameters within specific ranges, the invention achieves low-temperature fixing ability while preventing storage stability deterioration that occurs with excessive crystalline polyester content.
Solution Approach 2:
The composite resin binder system balances crystalline polyester (5-50 wt%) and amorphous polyester (50-95 wt%) with controlled glass transition temperature (40-80°C). This composition ratio and the amorphous component's properties compensate for the lower storage stability of high crystalline polyester content formulations, maintaining overall storage stability while achieving low fixing temperature.
3Temperature
If a crystalline polyester with low molecular weight is used to improve low-temperature fixing ability, then fixing temperature is reduced, but resin strength deteriorates
Solution Approach 1:
The invention optimizes the weight-average molecular weight of crystalline polyester within the range of 20,000-150,000. This molecular weight range provides optimal balance: lower molecular weight facilitates low-temperature fixing by enabling easier chain mobility and melting, while sufficiently high molecular weight maintains adequate resin strength and mechanical properties.
Solution Approach 2:
The composite resin binder system compensates for reduced resin strength from low molecular weight crystalline polyester through the amorphous polyester component. The amorphous polyester with controlled glass transition temperature (40-80°C) and appropriate molecular weight provides mechanical strength and structural integrity, allowing the use of lower molecular weight crystalline polyester for low-temperature fixing without sacrificing overall resin strength.
4Stability of the object's composition
If conventional resin formulations are used to maintain storage stability, then storage stability is maintained, but low-temperature fixing ability deteriorates
Solution Approach 1:
The invention employs a composite resin binder system with crystalline polyester (5-50 wt%) having low softening point (85-150°C) and controlled crystallinity (30-80%), combined with amorphous polyester (50-95 wt%) with glass transition temperature of 40-80°C. This composite formulation achieves low-temperature fixing ability (fixing temperature reduced to 150°C or below) while maintaining storage stability through the synergistic interaction of both resin components and controlled composition ratios.
Solution Approach 2:
The invention fundamentally changes the resin formulation parameters: introduces crystalline polyester with low softening point (85-150°C) and controlled crystallinity (30-80%), optimizes weight-average molecular weight (20,000-150,000), and controls the crystalline/amorphous polyester ratio (5-50/50-95 wt%). These parameter changes enable simultaneous achievement of low-temperature fixing ability and storage stability, overcoming the limitations of conventional single-resin formulations.
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 exhibits excellent low-temperature fixing ability, wide fixable region, and improved storage stability, along with suppression of uneven line formation on developer rollers, even in oil-less nonmagnetic monocomponent developing devices.
Implementation Method 1
a crystalline polyester obtained by polycondensing an alcohol component containing an aliphatic diol having 2 to 10 carbon atoms and a carboxylic acid component containing an aromatic dicarboxylic acid compound and an aromatic tricarboxylic or higher polycarboxylic acid compound
Data Source
AI summary
A toner for electrostatic image development containing at least a resin binder, the resin binder being composed of a crystalline resin and an amorphous resin, wherein the crystalline resin contains a crystalline polyester obtained by polycondensing an alcohol component containing an aliphatic diol having 2 to 10 carbon atoms and a carboxylic acid component containing an aromatic dicarboxylic acid compound and an aromatic tricarboxylic or higher polycarboxylic acid compound, wherein the crystalline polyester has a weight-average molecular weight of from 20,000 to 150,000, and wherein the crystalline resin and the amorphous resin are in a weight ratio, i.e. crystalline resin/amorphous resin, of from 55/45 to 95/5. The toner for electrostatic image development of the present invention can be suitably used in, for example, the development or the like of latent image formed in electrophotography, an electrostatic recording method, an electrostatic printing method, or the like.