Toner Annealing Process for Storage Stability
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Solution Overview
Problem
Toner systems for xerographic applications face challenges in maintaining storage stability and particle size integrity, with issues of agglomeration and offset onto fuser rollers, and require reduced fixing temperatures to conserve energy and extend fuser system lifetime.
Innovation Solution
A continuous annealing process is introduced, involving melt-mixing of amorphous and crystalline resins with colorants and optional waxes, followed by pelletizing and annealing at temperatures above the glass transition temperature to increase the toner's glass transition temperature, thereby enhancing storage stability and heat cohesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional melt kneading and extrusion processes are used to prepare toner particles, then toner can be produced with basic functionality, but the toner exhibits poor storage stability and particle size integrity leading to agglomeration
Solution Approach 1:
The patent applies preliminary action by conducting annealing treatment on toner particles before they are used in the xerographic process. The toner particles are heated to a temperature above their glass transition temperature (Tg) for a specific duration to reorganize their molecular structure, then cooled to lock in the improved properties. This pre-treatment ensures particles remain intact and resist agglomeration during storage and handling, addressing the reliability issue before the toner enters service.
Solution Approach 2:
The patent utilizes parameter changes by controlling the annealing temperature and time to modify the physical and chemical properties of the toner particles. Specifically, heating above the glass transition temperature alters the molecular mobility and free volume of the polymer matrix, improving particle stability. The patent specifies annealing at temperatures from Tg to Tg+50°C for 1-24 hours, which optimizes both storage stability and particle size integrity simultaneously.
2Reliability
If high fixing temperatures are used to fuse toner onto paper, then complete fusion and good image quality are achieved, but energy consumption increases and fuser system lifetime decreases
Solution Approach 1:
The patent applies parameter changes by modifying the glass transition temperature of the toner particles through controlled annealing. By heating the toner above its original Tg and holding it there, the polymer matrix reorganizes to achieve a new, higher Tg. This elevated Tg allows the toner to fuse at lower temperatures while maintaining complete fusion and image quality, thereby reducing energy consumption and extending fuser system lifetime.
Solution Approach 2:
The annealing process serves as a preliminary action that prepares the toner particles for low-temperature fusion. The pre-heating and structural reorganization during annealing creates toner particles with improved fusibility characteristics, enabling them to bond effectively at reduced temperatures without compromising image quality.
3Ease of manufacture
If toner is stored at ambient conditions without special treatment, then storage is simple and convenient, but toner particles agglomerate and lose their integrity over time
Solution Approach 1:
The patent applies preliminary action by performing annealing treatment during the toner manufacturing process, before the toner is packaged for storage. This pre-treatment stabilizes the particle structure and prevents agglomeration during subsequent storage and handling. The annealed toner maintains its particle size integrity under ambient storage conditions without requiring special environmental controls, thus preserving both storage simplicity and particle stability.
4Ease of manufacture
If the glass transition temperature of the toner is low, then toner is easier to process and fuse, but toner exhibits poor heat cohesion and offsets onto the fuser roller
Solution Approach 1:
The patent applies parameter changes by controlling the annealing temperature and duration to precisely adjust the glass transition temperature of the toner. By heating above the original Tg and maintaining it there for specific time periods, the polymer structure reorganizes to achieve an optimized Tg that provides adequate heat cohesion. This prevents hot offset onto the fuser roller while maintaining ease of processing and fusion.
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 process results in toners with improved storage stability, reduced plasticization, and increased glass transition temperature, preventing agglomeration and offset issues while allowing for lower fusing temperatures, thus reducing energy consumption and extending fuser system lifespan.
Implementation Method 1
continuously annealing the pelletized toner by heating the toner to a temperature of from about 50° C. to about 90° C. for a period of time from about 2 minutes to about 60 minutes, said temperature being above the glass transition temperature of the toner
Implementation Method 2
The present disclosure provides processes for producing toners which include a continuous annealing step, which increases the glass transition temperature of the resulting toner
Data Source
AI summary
The present disclosure provides processes for producing toners which include an annealing step and toners produced by these processes. The process includes a continuous annealing step, which increases the glass transition temperature of the resulting toner.