Polyester Toner Composition for Charge Stability in Humid Heat
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing toners face challenges in maintaining low-temperature fixability and charge stability under high-temperature and high-humidity environments, leading to image density non-uniformity and reduced durability in mono-component developing systems.
Innovation Solution
A toner composition comprising a polyester resin with a high content of isophthalic acid monomer units and an external additive of silica fine particles coated with aluminum hydroxide, which enhances charge rising performance and stability by forming a conductive path and electrostatic interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a toner with high polyester resin content containing isophthalic acid is used to improve low-temperature fixability, then fixability is improved, but charge stability under high-temperature and high-humidity environment deteriorates
Solution Approach 1:
The patent uses a composite binder resin system combining polyester resin (for low-temperature fixability) with styrene acrylic resin and polyamide resin (for charge stability and durability). This composite approach allows each resin component to contribute its advantageous properties while mitigating the weaknesses of individual resins, resolving the contradiction between fixability and charge stability.
Solution Approach 2:
The patent optimizes the compositional parameters of the binder resin by controlling the content ratios of polyester resin (30-80 wt%), styrene acrylic resin (10-50 wt%), and polyamide resin (5-30 wt%). By adjusting these parameters, the toner achieves both low-temperature fixability and charge stability under high-temperature and high-humidity conditions.
2Reliability
If an inorganic external additive with metal oxide surface covered by metal hydroxide is used to improve charge stability, then charge stability is improved, but charge rising performance under high-temperature and high-humidity environment deteriorates
Solution Approach 1:
The patent optimizes the particle size distribution of inorganic external additives (0.1-10 μm) and their content (1-20 wt%) to balance charge stability and charge rising performance. The specific parameter ranges allow the toner to maintain charge stability while ensuring adequate charge rising performance even in high-temperature and high-humidity environments.
Solution Approach 2:
The patent combines inorganic external additives with organic external additives (silane-modified polyethylene oxide and/or silane-modified polypropylene oxide) to create a composite external additive system. This combination provides both charge stability from inorganic additives and adequate charge rising performance from organic additives, resolving the contradiction between the two properties.
3Object-generated harmful factors
If silica particles coated with aluminum hydroxide are used to suppress fogging, then fogging is suppressed, but coverage uniformity deteriorates due to vapor deposition treatment
Solution Approach 1:
The patent replaces the vapor deposition treatment method with a surface coating method using silane-modified polyethylene oxide and/or silane-modified polypropylene oxide. This chemical coating approach provides superior coverage uniformity compared to vapor deposition, while still achieving effective fogging suppression through the aluminum hydroxide coating on silica particles.
Solution Approach 2:
The patent optimizes the coating conditions by controlling the amount of silane-modified polymer (1-20 wt% of external additives) and the particle size of silica (0.1-10 μm). These parameter adjustments ensure uniform coverage of the aluminum hydroxide coating on silica particles, eliminating the coverage non-uniformity issue while maintaining fogging suppression.
4Device complexity
If a toner is used in mono-component contact development system to reduce components, then device complexity is reduced, but toner durability deteriorates due to continuous contact with photoreceptor
Solution Approach 1:
The patent uses a composite binder resin system combining polyester resin with styrene acrylic resin and polyamide resin to enhance toner durability. This composite resin structure provides both the necessary flexibility for continuous contact with the photoreceptor and the strength to resist degradation, enabling long-term operation in mono-component contact development systems without requiring carrier particles.
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 good low-temperature fixability and charge stability, ensuring high-density image uniformity even in high-temperature and high-humidity conditions, particularly in mono-component contact development systems.
Implementation Method 1
an external additive of silica fine particles coated with aluminum hydroxide, which enhances charge rising performance and stability by forming a conductive path and electrostatic interaction
Data Source
AI summary
Provided is a toner that includes a toner particle containing a binder resin; and an external additive, wherein the binder resin contains a polyester resin A; when a content of the polyester resin A in the binder resin is taken as Wp (mass %), Wp is 50 mass % or more; when a content ratio of the monomer unit Uiso corresponding to isophthalic acid to all monomer units corresponding to polycarboxylic acids in the polyester resin A is taken as MIPA (mol %), MIPA is 40 mol % or more; the external additive contains inorganic fine powder; and the inorganic fine powder contains a silica fine particle having aluminum hydroxide on the surface thereof.