Toner Composition with Segmented Binder Resin for Low-Temperature Fixing
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Solution Overview
Problem
Conventional toners face challenges in achieving a wide range of fixing temperatures, superior low-temperature fixing ability, heat-resistant storage stability, and stable image density across varying environmental conditions, particularly with the use of plant-derived resins like polylactic acid, which suffer from moisture sensitivity and crystallinity issues.
Innovation Solution
A toner composition comprising an amorphous polyester resin with a polyhydroxycarboxylic acid skeleton of 80% or less optical purity, combined with a crystalline organic compound such as a crystalline polyester resin or low molecular compound, and a core-shell structure to enhance low-temperature fixing and heat-resistant storage stability, while maintaining image density stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the glass transition temperature of the binder resin is excessively decreased to achieve low temperature fixing ability, then the low temperature fixing ability is improved, but the heat resistant storage stability is degraded
Solution Approach 1:
The invention divides the binder resin into two distinct phases: a matrix phase containing a first binder resin with specific glass transition temperature (50-80°C) and a domain phase containing a second binder resin with lower glass transition temperature (0-50°C) dispersed within it. This segmentation allows each phase to fulfill different functions - the matrix phase provides heat resistant storage stability while the domain phase provides low temperature fixing ability, thereby resolving the contradiction between these two opposing requirements.
Solution Approach 2:
The invention creates a composite binder resin system by combining two different binder resins with distinct thermal properties into a single functional unit. The matrix phase binder resin and domain phase binder resin are compatible with each other, forming a stable composite structure where the domain phase is dispersed within the matrix phase. This composite structure enables the toner to exhibit both high heat resistant storage stability (from the matrix phase) and excellent low temperature fixing ability (from the domain phase), effectively resolving the technical contradiction.
2Temperature
If a fixing aid compatible with the binder resin is added to decrease the glass transition temperature, then the low temperature fixing ability is improved, but the binder resin is plasticized and the heat resistant storage stability is degraded
Solution Approach 1:
Instead of uniformly plasticizing the entire binder resin with a fixing aid, the invention segments the binder resin into two phases with different glass transition temperatures. The domain phase contains the fixing aid compatible with the second binder resin, creating a localized plasticized region that provides low temperature fixing ability without compromising the overall structural integrity and heat resistant storage stability provided by the matrix phase.
3Adaptability or versatility
If polylactic acid is used as a plant-derived binder resin, then environmental sustainability is improved, but moisture sensitivity and crystallinity issues arise
Solution Approach 1:
The invention creates a composite binder resin system where the matrix phase contains a first binder resin (which can be polylactic acid or other resins) and the domain phase contains a second binder resin with specific properties (glass transition temperature 0-50°C). This composite structure allows the use of environmentally sustainable plant-derived resins like polylactic acid while the domain phase modulates the overall moisture sensitivity and thermal properties, preventing excessive crystallinity and improving 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 a wide range of fixing temperatures, improved low-temperature fixing ability, and enhanced heat-resistant storage stability, along with stable image density under different environmental conditions, effectively addressing the limitations of plant-derived resins.
Implementation Method 1
by adding a material which is compatible with the binder resin and exhibits plasticization effect (hereinafter, referred to as a fixing aid) to a toner, the glass transition temperature (Tg) of the binder resin can be decreased
Implementation Method 2
a crystalline organic compound which has a melting point of 60°C to 100°C
Implementation Method 3
a large amount of electric power is necessary in the course of heat melting and fixing a toner onto a recording medium such as paper
Data Source
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AI summary
A toner including: a first binder resin; a colorant; a releasing agent; and a crystalline organic compound, wherein the first binder resin contains an amorphous polyester resin (a) having a polyhydroxycarboxylic acid skeleton derived from optically active monomers in a part of a main chain of the amorphous polyester resin, and the polyhydroxycarboxylic acid skeleton has an optical purity X, calculated on the monomer basis, of 80% or less, and the optical purity X is determined from the following equation, OpticalPurityX%=XL-form-XD-form where X (L-form) represents, calculated on the monomer basis, an L-form ratio (mol%), and X (D-form) represents, calculated on the monomer basis, a D-form ratio (mol%), and wherein the crystalline organic compound is any one of a crystalline polyester resin (b) and a crystalline low molecular compound which has a melting point of 60°C to 100°C, and is selected from a group consisting of fatty acid having 16 to 24 carbon atoms, alcohol having 16 to 24 carbon atoms, a fatty acid ester compound, and aliphatic carboxylic acid amide.