Particulate Release Agent via Supercritical Fluid Depressurization
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Solution Overview
Problem
Existing toner production methods face challenges in achieving high yield with small average particle diameter, preventing toner adhesion to image bearing members, and maintaining image quality over time, while also ensuring effective release from heated fixing members.
Innovation Solution
A novel toner production method involving a particulate release agent prepared by heating a release agent to its melting point, dissolving it in a supercritical or sub-critical fluid, and quickly expanding the solution to form particles, which are then incorporated into a toner composition along with a binder resin and colorant, using a polymer chain growth method to create uniform toner particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pulverization methods are used to produce fine toner particles with small diameter, then image resolution and half toner property are improved, but yield deteriorates due to removal of fine and coarse particles in classification
Solution Approach 1:
The invention changes the fundamental parameter of toner particle formation from mechanical pulverization to controlled polymerization. By using polymer emulsion aggregation or suspension polymerization, toner particles are formed directly at the desired size range without subsequent classification, eliminating yield loss while achieving uniform particle diameter distribution suitable for high-quality imaging.
Solution Approach 2:
The invention performs preliminary preparation of polymer emulsion with controlled properties before particle formation. By pre-adjusting the polymer emulsion characteristics (molecular weight, composition, charge) and controlling the aggregation or polymerization conditions, toner particles are formed directly with the desired size distribution, avoiding the need for post-formation classification that causes yield deterioration.
2Length of moving object
If pulverization methods are used for toner production, then particle size can be reduced, but even dispersion of colorant and charge controlling agent in binder resin becomes difficult
Solution Approach 1:
The invention changes the production method from mechanical size reduction to controlled polymerization/aggregation. This allows colorant and charge controlling agent to be incorporated into the binder resin matrix during the polymer formation process itself, ensuring uniform molecular-level dispersion rather than mechanical mixing, thereby achieving both small particle size and homogeneous composition.
Solution Approach 2:
The invention merges the formation of binder resin with the incorporation of colorant and charge controlling agent into a single integrated process. Through polymer emulsion aggregation or suspension polymerization, all components are combined and formed into toner particles simultaneously, ensuring uniform distribution of additives within the binder resin matrix from the outset.
3Reliability
If release agent is included in toner to prevent adhesion to heated fixing member, then fixing release is improved, but toner adhesion to image bearing member occurs
Solution Approach 1:
The invention applies local quality by incorporating release agent specifically into the surface region of toner particles rather than uniformly throughout. Through the controlled polymerization and aggregation process, release agent concentrates at the particle surface, providing effective fixing release properties while minimizing interference with electrostatic adhesion to the image bearing member, thus resolving the contradiction between these two opposing requirements.
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
This method enables the production of toners with a sharp particle diameter distribution, improved adhesion prevention, and sustained image quality over time, while maintaining high temperature preservability and low temperature fixability, thus addressing the issues of yield, adhesion, and image quality.
Implementation Method 1
heating the release agent to a temperature not lower than the melting point of the release agent to melt the release agent
Implementation Method 2
dissolving the melted release agent in a supercritical fluid or a sub-critical fluid
Implementation Method 3
feeding the solution into a liquid to depressurize (i.e., quickly expand) the solution, so that the particulate release agent is formed in the liquid
Data Source
AI summary
A toner for developing an electrostatic image is provided. The toner includes at least a binder resin; a colorant; and a particulate release agent. The particulate release agent is prepared by heating the release agent to a temperature not lower than a melting point of the release agent to melt the release agent, dissolving the melted release agent in a supercritical fluid or a sub-critical fluid, and feeding the solution into a liquid so that the solution is depressurized and the particulate release agent is formed in the liquid.