Toner Silica Surface Treatment for Charge Stability
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Solution Overview
Problem
Existing toners face challenges in maintaining excellent charge rising properties, particularly in low print intermittent modes under low-temperature and low-humidity environments, leading to excessive chargeability and density unevenness.
Innovation Solution
A toner composition featuring a binder resin and silica fine particles with a dimethylsiloxane structure and dodecylbenzenesulfonic acid, where the silica fine particles are surface-treated to control silanol groups and boron-oxygen bonds, ensuring balanced chargeability and fluidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silica treated with dimethyldichlorosilane is used as external additive to improve chargeability, then charge rising property is improved, but chargeability becomes excessive in low print intermittent mode leading to density unevenness
Solution Approach 1:
The patent changes the chemical parameters of the silica surface treatment by specifying precise ratios of dimethylsiloxane groups to silanol groups. The silanol group content is controlled to 0.05-2.0 mmol/g, and the dimethylsiloxane-to-siloxane ratio is controlled to 0.1-5.0, which modulates the chargeability to prevent excessive charging while maintaining good charge rising properties
Solution Approach 2:
The patent creates a composite surface structure on silica particles by combining multiple functional groups (siloxane, silanol, and dimethylsiloxane groups) in specific proportions. This composite material approach allows balancing between charge rising property and chargeability stability that cannot be achieved with single-function treatments
2Productivity
If toner is charged frequently in low print intermittent mode, then charge rising opportunity increases, but chargeability becomes excessive causing rapid decrease when mixed with low chargeability toner
Solution Approach 1:
The patent modifies the surface chemical parameters of silica to create a buffer effect against frequent charging cycles. By controlling silanol group content and dimethylsiloxane ratios, the silica surface can accommodate repeated charging without developing excessive chargeability, preventing the rapid chargeability decrease that occurs when such toner mixes with low chargeability toner
3Reliability
If silica fine particle surface is treated to improve chargeability, then fluidity and charge rising property improve, but control over chargeability becomes difficult under low-temperature and low-humidity environment
Solution Approach 1:
The patent designs a composite surface treatment on silica particles that combines hydrophobic dimethylsiloxane groups with polar silanol groups. This composite structure provides environmental adaptability by maintaining stable chargeability characteristics across different temperature and humidity conditions, preventing both excessive chargeability and poor charge rising in low-temperature, low-humidity environments
Solution Approach 2:
The patent optimizes physical and chemical parameters of the silica surface, including particle size (3-10 μm), specific surface area (5-50 m²/g), and surface group composition. These parameter changes enable the toner to maintain consistent performance across varying environmental conditions
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 solution effectively suppresses excessive electrostatic charging while maintaining high charge rising properties, ensuring stable image formation even in challenging environmental conditions.
Implementation Method 1
a silica fine particle A, wherein (I) in TOF-SIMS measurement of the toner particle, a fragment peak derived from a boron atom and a fragment peak derived from a boron-oxygen structure are detected
Implementation Method 2
The charge rising property of the toner can be improved by enhancement of the chargeability and fluidity of the toner
Implementation Method 3
the toner comprises at least one selected from the group consisting of dodecylbenzenesulfonic acid and a dodecylbenzenesulfonate
Implementation Method 4
the toner comprises at least one selected from the group consisting of dodecylbenzenesulfonic acid and a dodecylbenzenesulfonate; (II) in measurement of the silica fine particle A by time-of-flight type secondary ion mass spectrometry, a fragment ion is observed which corresponds to a structure shown by the following Formula (1)
Data Source
AI summary
The present invention provides a toner which can form a stable image even in a low print intermittent mode under a low-temperature and low-humidity environment, while having excellent charge rising property. A toner includes a toner particle and a silica fine particle A, wherein (I) in TOF-SIMS measurement of the toner particle, a fragment peak derived from a boron atom and a fragment peak derived from a BO structure are detected, and the toner contains dodecylbenzenesulfonic acid or a dodecylbenzenesulfonate; (II) in TOF-SIMS measurement of the silica fine particle A, a fragment ion is observed which corresponds to a dimethylsiloxane structure; when 2.00 g of the silica fine particle is dispersed in a mixed liquid of 25.0 g of ethanol and 75.0 g of an aqueous solution of 20% by mass of NaCl, and the dispersion is subjected to a titration operation which uses sodium hydroxide, Sn defined by Sn=[(a−b)×c×NA]/(d×e) satisfies 0.10≤Sn≤0.80.