Polyester Toner Crystallinity and Storage Stability
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Solution Overview
Problem
Existing toners face challenges in achieving both excellent low-temperature fixing performance and long-term storage stability, particularly under severe fixing conditions with low internal fixing pressure, where they tend to degrade in heat-resistant storage and exhibit image curling due to incomplete crystallization and phase separation.
Innovation Solution
A toner composition comprising polyester resin A with a crystal nucleating agent segment bonded to its end and polyester resin B, where the SP values of these resins are carefully controlled to ensure compatibility and phase separation, allowing for reversible phase transition and improved crystallinity, thereby enhancing low-temperature fixing and storage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the compatibility between crystalline resin and amorphous resin is increased to improve low temperature fixing property, then the low temperature fixing property is improved, but the heat-resistant storage property and crystallizability are degraded
Solution Approach 1:
The invention changes the chemical structure parameters of the crystalline resin by introducing specific segments (adipic acid segment, cycloaliphatic dicarboxylic acid segment, and/or alicyclic diol segment) to control the SP value within 9.0-10.5. This parameter optimization allows the resin to maintain appropriate compatibility with amorphous resin for low-temperature fixing while preserving sufficient crystallizability and heat-resistant storage property.
Solution Approach 2:
The invention creates a composite resin system by combining crystalline resin with specific functional segments and amorphous resin in controlled proportions (crystalline resin 10-60 parts, amorphous resin 40-90 parts). This composite structure enables the toner to exhibit both low-temperature fixing capability and heat-resistant storage stability through the synergistic effect of the two resin types.
2Stability of the object's composition
If the compatibility between amorphous resin and crystalline resin is lowered to improve crystallizability, then the crystal formation is facilitated, but the low temperature fixing property is degraded under severe conditions
Solution Approach 1:
The invention optimizes the SP value parameter of the crystalline resin to fall within 9.0-10.5 by incorporating specific chemical segments. This parameter control ensures that the compatibility between crystalline and amorphous resin is neither too high nor too low, thereby maintaining both crystallizability and low-temperature fixing property under severe fixing conditions.
3Speed
If inorganic crystal nucleating agent content is increased to accelerate crystallization, then the crystallization speed is improved, but the melt viscosity increases and charging characteristic is affected
Solution Approach 1:
The invention extracts the crystal nucleating function from inorganic additives and transfers it to the molecular structure of the crystalline resin itself through the incorporation of adipic acid segments, cycloaliphatic dicarboxylic acid segments, and/or alicyclic diol segments. This eliminates the need for inorganic nucleating agents, avoiding their harmful effects on melt viscosity and charging characteristics while maintaining fast crystallization speed.
4Speed
If organic crystal nucleating agent is used to accelerate crystallization, then the crystallization is promoted, but the agent segregates on toner surface and shows insufficient effect
Solution Approach 1:
The invention removes external organic nucleating agents from the toner system and instead integrates crystal-nucleating functional segments directly into the crystalline resin polymer chain. This ensures that the nucleating function is permanently embedded in the resin structure, preventing segregation and ensuring consistent crystallization performance and storage stability.
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 improved low-temperature fixing properties and long-term storage stability, preventing image curling and peeling, even under severe conditions, by balancing compatibility and phase separation through controlled SP values and molecular weights.
Implementation Method 1
a polyester resin A containing a polyester portion (I) having a segment capable of forming a crystal structure and a crystal nucleating agent segment which is bonded to an end of the polyester portion (I)
Implementation Method 2
allowing for reversible phase transition and improved crystallinity, thereby enhancing low-temperature fixing and storage stability
Implementation Method 3
the SP values Sa and Sb satisfy the following relationships: 9.00≦Sa≦10.50; and −0.40≦Sb−Sa≦0.80
Data Source
AI summary
The toner includes toner particles containing a polyester resin A, a polyester resin B and a colorant, the polyester resin A has a polyester portion including a segment capable of forming a crystal structure and a crystal nucleating agent segment, which is bonded to an end of the polyester portion, and the polyester resin B is a resin which is free of any segments capable of forming a crystal structure, the polyester resin B has a weight average molecular weight Mwb by GPC of a THF soluble matter of 3000 or more and 100000 or less, and an SP value Sa ((cal/cm3)1/2) of the polyester portion of the polyester resin A and an SP value Sb ((cal/cm3)1/2) of the polyester resin B satisfy the following relationships:9.00≦Sa≦10.50−0.40≦Sb−Sa≦0.80.