Composite Toner Binder Resin for Fixing and Stability
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Solution Overview
Problem
High-speed electrophotographic machines face issues with image density non-uniformity and reduced developing performance due to the use of crystalline resins, which affect low-temperature fixability and heat-resistant storage stability, as they lead to charge leaks and uneven toner charging.
Innovation Solution
A toner formulation with a binder resin comprising a polymer A that includes specific monomer units with controlled solubility parameters and molecular weight, ensuring high storage elastic modulus and maintaining crystallinity for improved low-temperature fixability and heat-resistant storage stability, while preventing charge leakage and ensuring uniform image density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a large amount of crystalline vinyl resin is used to improve sharp-melt property, then low-temperature fixability is improved, but image density non-uniformity during fixing worsens
Solution Approach 1:
The invention uses a composite binder resin system combining crystalline vinyl resin (5-50 mass%) with amorphous polymer (50-95 mass%). This composite structure allows the crystalline component to provide sharp-melt property for low-temperature fixability while the amorphous component maintains consistent viscosity and prevents image density non-uniformity during fixing.
Solution Approach 2:
The invention optimizes the content ratio of crystalline vinyl resin to amorphous polymer, specifying crystalline vinyl resin at 5-50 mass% and amorphous polymer at 50-95 mass%. This parameter control ensures sufficient sharp-melt property while preventing excessive sensitivity to temperature fluctuations that causes image density non-uniformity.
2Reliability
If crystalline resin is used to improve heat-resistant storage stability, then storage stability is improved, but developing performance worsens due to charge leaks
Solution Approach 1:
The composite binder resin system combines crystalline vinyl resin (providing heat-resistant storage stability through its crystalline structure) with amorphous polymer (maintaining charge retention capability). This composite structure prevents charge leaks while preserving developing performance, resolving the contradiction between storage stability and developing performance.
Solution Approach 2:
The invention controls the crystalline vinyl resin content at 5-50 mass%, which is sufficient to provide heat-resistant storage stability but limited enough to prevent excessive charge leakage that would degrade developing performance. This optimized parameter range balances both requirements.
3Temperature
If glass transition temperature of amorphous binder resin is reduced to improve low-temperature fixability, then fixability is improved, but heat-resistant storage stability worsens
Solution Approach 1:
The invention utilizes the phase transition characteristics of crystalline vinyl resin, which has a sharp melting point rather than a gradual glass transition. This allows the toner to exhibit low-temperature fixability through sharp melting while maintaining heat-resistant storage stability through its crystalline structure, avoiding the trade-off inherent in amorphous resins.
Solution Approach 2:
The composite system combines crystalline vinyl resin (providing both low-temperature fixability and heat-resistant storage stability) with amorphous polymer. This allows achieving low-temperature fixability without reducing glass transition temperature, thereby maintaining heat-resistant 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 achieves excellent heat-resistant storage stability, low-temperature fixability, and image density uniformity, enhancing developing performance and compatibility with high-speed machines.
Implementation Method 1
the melting point is 60°C to 80°C
Implementation Method 2
crystalline resins have the property of not changing their states before the melting point. Because they form regular arrays of molecules, moreover, they have a sharp-melt property of melting rapidly at the melting point.
Data Source
AI summary
A toner comprising a toner particle containing a binder resin, the storage elastic modulus Gt' (150) of the toner at 150°C is at least 1.0 × 104 Pa, the binder resin contains a polymer A having a first monomer unit derived from a first polymerizable monomer and a second monomer unit derived from a second polymerizable monomer different from the first polymerizable monomer, the first polymerizable monomer is selected from specific (meth)acrylic acid esters, the contents of the first monomer unit and second monomer unit in the polymer A are within specific ranges, and the SP values of the first monomer unit and second monomer unit are within specific ranges.