Crystalline Polyester Toner for Offset and Fogging
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Solution Overview
Problem
The existing toner formulations face challenges in maintaining high-quality image output under high-temperature and high-humidity environments, particularly with regards to trailing end offset, density unevenness, and fogging, due to the compatibility of crystalline polyester with the binder resin, which affects viscoelastic properties and charge stability.
Innovation Solution
A toner composition with specific viscoelastic modulus ranges and domain size control of crystalline polyester and wax, ensuring a melting point between 65°C and 80°C, and storage elastic modulus values at 50°C, 80°C, and 120°C that satisfy certain ratios, enhancing the toner's stability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If crystalline polyester is used to improve low-temperature fixing performance, then fixing performance is improved, but charge stability deteriorates due to surface seepage
Solution Approach 1:
The patent applies local quality by creating a dual-layer structure where the toner particle surface has different composition from the interior. The surface layer is enriched with binder resin and depleted of crystalline polyester, while the interior maintains high crystalline polyester content for low-temperature fixing. This spatial differentiation resolves the contradiction by localizing the crystalline polyester away from the surface, preventing charge instability while preserving fixing performance.
Solution Approach 2:
The patent uses composite materials by combining crystalline polyester, binder resin, and external additives in a structured composite where each component serves specific functions. The crystalline polyester provides low-temperature fixing capability, the binder resin provides charge stability, and their controlled phase separation creates a composite structure that achieves both fixing performance and charge stability simultaneously.
2Stability of the object's composition
If crystalline polyester compatibility with binder resin is reduced to prevent surface seepage, then charge stability is improved, but low-temperature fixing performance deteriorates
Solution Approach 1:
The patent resolves this contradiction by applying local quality differently - the interior maintains low compatibility for charge stability while the surface achieves high compatibility through phase separation. The crystalline polyester is distributed such that it remains incompatible with binder resin in the bulk (preventing seepage) but creates surface enrichment of binder resin that provides charge stability without sacrificing interior fixing performance.
3Reliability
If storage elastic modulus is increased to prevent fogging, then resistance to severe environment is improved, but trailing end offset under high-temperature high-humidity conditions worsens
Solution Approach 1:
The patent applies phase transitions by utilizing the melting behavior of crystalline polyester at specific temperatures. The crystalline polyester melts at a controlled temperature range during the fixing process, providing temporary reduction in storage elastic modulus that enables trailing end offset prevention. After fixing, the crystalline polyester re-crystallizes, restoring high storage elastic modulus for fogging resistance. This temporal phase transition resolves the contradiction between maintaining high modulus for environmental resistance and allowing modulus reduction for offset prevention.
4Stability of the object's composition
If crystalline polyester degree of crystallinity is increased to reduce surface presence, then charge stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-forming toner particles with controlled crystalline polyester distribution and crystallinity before final processing. The crystalline polyester is pre-positioned in the interior of toner particles during particle formation, and pre-crystallization is achieved during the particle creation process itself. This preliminary structuring simplifies subsequent manufacturing steps while ensuring the desired charge stability through high interior crystallinity.
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 effectively suppresses trailing end offset, density unevenness, and fogging, even under severe environmental conditions, by controlling the viscoelastic behavior and domain structure, resulting in improved image quality and durability.
Implementation Method 1
the crystalline polyester becomes rapidly compatible with the binder resin of the toner and promotes melt deformation of the toner
Implementation Method 2
promotes melt deformation of the toner
Implementation Method 3
the degree of crystallinity of the crystalline polyester is improved by controlling the cooling rate
Implementation Method 4
an annealing step is provided during cooling to increase the degree of crystallinity
Implementation Method 5
controlling viscoelastic characteristics of the toner has been extensively studied
Data Source
AI summary
A toner comprises toner particles, each of which contains a binder resin, a colorant, a wax and a crystalline polyester. The melting point P(t) of the crystalline polyester is at least 65.0° C. and not more than 80.0° C., and regarding a storage elastic modulus G′ obtained in dynamic viscoelasticity measurement of the toner, where G′ at 50° C. is denoted by G′(50), G′ at 80° C. is denoted by G′(80), G′ at 120° C. is denoted by G′(120), and G′ at the melting point P(t) of the crystalline polyester is denoted by G′(t), the following formulas are satisfied: 4.2×108 Pa≤G′(50), 3.0×102≤G′(50)/G′(80), and G′(t)/G′(120)≤7.0×102.