Toner Resin Phase Separation for Fixing and Storage
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Solution Overview
Problem
Conventional toners face challenges in achieving both excellent low-temperature fixing performance and long-term storage stability under high-temperature environments, especially when used in systems with low fixing nip internal pressure and rapid image formation, where compatibility between amorphous and crystalline resins is difficult to balance for optimal results.
Innovation Solution
A toner composition comprising polyester resin A with a crystalline portion and polyester resin B without crystalline capabilities, where the molecular weight distribution and solubility parameters are specifically tailored to allow phase separation at room temperature and compatibility at elevated temperatures, using a crystal nucleating agent to enhance crystallinity and control the phase transition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the compatibility between amorphous resin and crystalline 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 patent applies parameter changes by precisely controlling the solubility parameters (SP values) of both amorphous and crystalline resins to fall within specific ranges, and by limiting the compatibility ratio between them. This quantitative control allows the system to achieve optimal low-temperature fixing while preventing excessive compatibility that would harm storage stability. The SP value parameters serve as controllable variables to balance the contradiction.
Solution Approach 2:
The patent uses a composite material system combining amorphous resin and crystalline resin in specific proportions (amorphous:crystalline = 70:30 to 90:10). This composite approach allows the system to benefit from both resin types - the amorphous resin provides low-temperature flexibility while the crystalline resin provides structural stability, achieving a balance between fixing performance and storage reliability.
2Reliability
If the compatibility between amorphous resin and crystalline resin is decreased to improve heat-resistant storage property, then the heat-resistant storage property is improved, but the low-temperature fixing property is degraded
Solution Approach 1:
The patent resolves this contradiction by adjusting the solubility parameter values within specific ranges and controlling the compatibility ratio. By making minor adjustments to these parameters, the system achieves sufficient compatibility for acceptable fixing performance while preventing excessive compatibility that would compromise storage stability. This parameter optimization allows simultaneous satisfaction of both requirements.
3Reliability
If the content of low molecular weight component in resin is decreased to improve resistance to deterioration, then the resistance to deterioration is improved, but the fixing property under low pressure cannot be sufficiently attained
Solution Approach 1:
The patent employs a composite resin system where amorphous and crystalline resins work synergistically. The amorphous resin with controlled low molecular weight content provides flexibility and adhesion under low pressure, while the crystalline resin contributes structural integrity and resistance to deterioration. This composite approach allows the system to achieve both fixing performance and durability that cannot be obtained with a single resin type.
Solution Approach 2:
The patent applies local quality by having different resin components perform different functions within the same toner system. The amorphous resin primarily provides low-temperature flexibility and adhesion, while the crystalline resin provides structural stability and durability. This functional differentiation allows each component to optimize its contribution without compromising the other.
4Temperature
If amorphous polyester and crystalline polyester are used to improve low-temperature fixing property, then the low-temperature fixing property and glossiness are improved, but the toner becomes overly plasticized and may block under high temperature and high humidity
Solution Approach 1:
The patent resolves this contradiction by precisely controlling the solubility parameters and compatibility ratio between amorphous and crystalline polyesters. By limiting the compatibility to specific ranges, the system achieves sufficient low-temperature fixing performance while preventing excessive plasticization that would cause blocking under high temperature and humidity conditions. This parameter control balances flexibility with thermal 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 achieves improved low-temperature fixing properties and storage stability, maintaining image quality even under high-temperature conditions and low pressure, with controlled phase transition ensuring effective adhesion and preventing image peeling or glossiness unevenness.
Implementation Method 1
a crystal nucleating agent portion, which is bonded to an end of the polyester portion
Implementation Method 2
allow phase separation at room temperature and compatibility at elevated temperatures
Data Source
AI summary
The toner of the present invention includes toner particles containing polyester resins A and B and a colorant, the A has a polyester portion including a portion capable of forming a crystal structure and a crystal nucleating agent portion, which is bonded to an end of the polyester portion, the B is free from any portions capable of forming a crystal structure, in a chart obtained as a result of GPC of a THF-soluble matter of the B, a ratio of a component having a molecular weight of 1500 or less in the B is 5.0 to 15.0% by area, and when an SP value of the polyester portion of the A is represented by Sa ((cal/cm3)1/2) and an SP value of the B is represented by Sb ((cal/cm3)1/2), the SP values Sa and Sb satisfy the following relationships:9.50≦Sa≦11.00−0.65≦Sb−Sa≦0.70.