Screen Device for Toner Production Preventing Mesh Clogging
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Solution Overview
Problem
Current methods for producing toners for electrostatic charge images struggle to achieve high image quality and scratch resistance while efficiently removing coarse particles, leading to clogging issues in the screening process and poor yield.
Innovation Solution
A method involving a specific screening process where toner host particles are passed through a screen with a particular configuration, characterized by a formula that ensures efficient particle passage without clogging, and a screen device with specific properties such as vibration and material characteristics to change mesh openings dynamically, allowing continuous screening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet methods (suspension polymerization, emulsion polymerization flocculation, or dissolution suspension) are used to produce toner host particles, then particle diameter control and narrow distribution are improved, but coarse particles still form due to agglomeration and deposition, and shape control remains inadequate
Solution Approach 1:
The screen is vibrated in the vertical direction during the screening process to prevent coarse particles from clogging the mesh openings. The vibration causes particles to bounce and prevents them from settling and blocking the screen, enabling continuous operation without clogging while effectively removing coarse particles
Solution Approach 2:
The screening step is performed on the toner host particles before auxiliary agents are added. This preliminary screening removes coarse particles at the earliest stage possible, preventing them from causing agglomeration issues in subsequent processing steps and ensuring high-quality toner particles
2Object-generated harmful factors
If dry screening is performed after adding auxiliary agents to remove coarse particles, then coarse particle removal is achieved, but screen clogging occurs frequently, reducing productivity and increasing operational costs
Solution Approach 1:
The screen device applies vertical vibration during screening to prevent coarse particles from settling and clogging the mesh. This mechanical vibration keeps the screen surface active, allowing continuous operation without frequent interruptions for screen cleaning or replacement
Solution Approach 2:
The toner host particles are screened in a liquid medium (water or alcohol), which prevents static accumulation and reduces particle adhesion to the screen surface. The liquid medium facilitates smoother particle flow through the screen openings, reducing clogging compared to dry screening
3Productivity
If conventional screen devices are used for continuous screening, then high productivity is maintained, but screen clogging occurs, increasing device complexity and operational costs
Solution Approach 1:
The screen device incorporates a vibration mechanism that operates continuously during screening. This vibration system prevents clogging without requiring complex additional components for screen maintenance, simplifying the overall device while enabling continuous operation
Solution Approach 2:
The screening is performed in a liquid medium rather than dry conditions, fundamentally changing the operational parameters. This parameter change reduces particle adhesion and static accumulation, allowing continuous screening without the complex maintenance systems required by conventional dry screening devices
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 approach enables the production of toners with excellent image characteristics and scratch resistance, maintaining high yield and reducing clogging, thus prolonging screen life and lowering installation and running costs.
Implementation Method 1
the shape of the minimum opening unit of the screen to let particles pass therethrough, changes from the stationary state by vibration during the screening step
Data Source
AI summary
To provide a method for producing a toner for developing an electrostatic charge image, which is capable of producing toner host particles in good yield and which is excellent in image characteristics, image quality, scratch resistance of a developing device and toner consumption, and a screen device which is capable of screening continuously without clogging.A method for producing a toner for developing an electrostatic charge image, which comprises a step of screening a dispersion of toner host particles by a screen, characterized in that when the above step is carried out, Y≦{1/(M2+r2+2Mr)}×108×0.6 is satisfied where Y is the number of particles (number/cm2) existing on the screen and having sizes of at least the mesh size of the screen, M is the mesh size (μm) of the screen, and r is the diameter (μm) of wire constituting the screen; a screen device characterized in that the screen is one wherein the shape of the minimum opening unit to let particles pass therethrough, changes from the stationary state by vibration in the screening step; a screen device characterized in that the screen is one to which substantially no tension is applied; and a method for producing a toner for developing an electrostatic charge image, which employs such a screen device.