Toner Binder Resin Crystallization Control for Low-Temp Fixing
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Solution Overview
Problem
Toner for developing electrostatic images faces challenges in maintaining low-temperature fixing properties during storage at high temperatures due to accelerated crystallization of crystalline polyester resin, leading to impaired fixing properties and poor charging characteristics.
Innovation Solution
A toner composition with a binder resin containing a vinyl resin component and a crystalline polyester resin component, where the crystalline polyester resin has alkyl chains of different lengths repeated via ester bonds, and the vinyl resin component has a structural unit derived from an alkyl (meth)acrylate monomer, which retards crystallization and maintains microdispersion of crystalline domains, ensuring superior low-temperature fixing properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If crystalline polyester resin is used to improve low-temperature fixing properties, then fixing properties at low temperatures are improved, but crystallization accelerates during high-temperature storage, impairing fixing properties
Solution Approach 1:
The patent changes the chemical structure parameters of the crystalline polyester resin by controlling the difference in carbon atom numbers between polyvalent carboxylic acid and polyhydric alcohol components. By setting |Cacid - Calcohol| within 2-10, the resin achieves optimal balance between low-temperature fixing capability and high-temperature storage stability, preventing accelerated crystallization while maintaining fixing properties.
Solution Approach 2:
The patent creates a composite binder resin system combining crystalline polyester resin with amorphous resin components (styrene-acrylic copolymer and polyether modified polyester resin). This composite structure allows the crystalline component to provide low-temperature fixing while the amorphous components inhibit excessive crystallization during storage, resolving the contradiction between fixing performance and storage stability.
2Reliability
If compatibility between crystalline resin and amorphous resin is increased to prevent crystalline domain exposure, then charging characteristics improve, but plasticization occurs before thermal fixation, reducing thermal resistance
Solution Approach 1:
The patent optimizes the compatibility parameter between crystalline and amorphous resins by controlling the carbon atom difference |Cacid - Calcohol| and selecting specific amorphous resin components. This creates moderate compatibility that prevents crystalline domain exposure (improving charging) while avoiding excessive plasticization (maintaining thermal resistance).
Solution Approach 2:
The patent creates local quality differentiation in the binder resin structure, where crystalline polyester resin domains are dispersed within an amorphous resin matrix. The crystalline domains maintain their structure for charging characteristics, while the amorphous matrix provides thermal resistance, achieving both requirements simultaneously.
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 maintains superior low-temperature fixing properties and thermal resistance even after storage at high temperatures, preventing exposure of crystalline domains and ensuring consistent image quality.
Implementation Method 1
accelerated crystallization of the crystalline polyester resin during transportation of the toner in high-temperature environments (e.g., 40 to 50° C.) or during storage of the toner in an image-forming apparatus at such high temperatures
Implementation Method 2
Such a toner requires a reduction in melting temperature or melting viscosity of a binder resin contained in the toner
Data Source
AI summary
Provided is a toner for developing electrostatic images containing a toner particle. The toner particle contains a binder resin and a release agent. The binder resin contains a vinyl resin component and a crystalline polyester resin component. The vinyl resin component has a structural unit derived from an alkyl (meth)acrylate monomer represented by Formula (1):H2C═CR1—COOR2 Formula (1):In Formula (1), R1 represents a hydrogen atom or a methyl group, and R2 represents an alkyl group having 8 to 22 carbon atoms.The crystalline polyester resin component satisfies Formula (2):5≤|Cacid−Calcohol|≤12 Formula (2):In Formula (2), Calcohol represents the number of carbon atoms of the main chain of a structural unit derived from a polyhydric alcohol and Cacid represents the number of carbon atoms of the main chain of a structural unit derived from a polyvalent carboxylic acid.