White Toner Particle Ratio for Masking and Fixability
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Solution Overview
Problem
Conventional white toners fail to adequately balance masking performance on recording media and low-temperature fixability in electrophotography systems, leading to image defects such as fogging and reduced image intensity.
Innovation Solution
An image formation method and toner set where the volume median diameter and average circularity of the white toner and adjacent toner layers are optimized within specific ratios (Dw/Dc < 1.300 and Sc/Sw < 1.060) to improve masking performance and low-temperature fixability, using a combination of white and color toners with crystalline polyester resin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the content of white pigment in the white toner is increased to improve masking performance, then the masking ability improves, but the electrostatic chargeability deteriorates causing fogging and decreased image intensity
Solution Approach 1:
The patent applies parameter changes by precisely controlling the volume median diameter (Dw) and average circularity (Sw) of white toner particles, and their ratios to color toner parameters (Dc, Sc). By optimizing Dw/Dc to 0.950-1.200 and Sc/Sw to 0.980-1.030, the patent achieves both adequate pigment content for masking and proper electrostatic chargeability for image formation.
2Ease of manufacture
If a conventional white toner is used, then the masking function can be provided, but the low temperature fixability is insufficient
Solution Approach 1:
The patent employs parameter changes by optimizing the physical parameters of white toner particles (diameter and circularity) to enable low-temperature fixation. The controlled Dw and Sw values, along with their ratios to color toner parameters, allow the white toner to be fixed at lower temperatures while maintaining masking performance.
Solution Approach 2:
The patent uses composite materials by combining white and color toners with specific physical property ratios. This composite approach allows the white toner layer to provide masking while the optimized particle characteristics enable low-temperature fixation of the entire toner image.
3Ease of manufacture
If the particle size of white toner is increased to improve masking, then the masking ability improves, but the image intensity in fixing decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the volume median diameter (Dw) of white toner and its ratio to color toner diameter (Dc). By setting Dw/Dc to 0.950-1.200, the patent optimizes particle size to achieve both adequate masking ability and high image intensity during fixation.
Data Source
AI summary
The invention provides an image formation method, a toner set, and a white toner, by which a masking function of an image layer formed by a white toner on a recording medium can be developed efficiently, and low temperature fixability can be improved. An image formation method for fixing an image forming layer (A) to be formed using a white toner, and an image forming layer (B) to be formed adjacent to the image forming layer (A) using a toner different from the white toner on a recording medium; wherein the following relational expressions (1) and (2) are satisfied:1.000<Dw/Dc<1.300 (1);and1.000<Sc/Sw<1.060 (2).