Toner Binder Resin Low-Temperature Fixation and Stability

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Solution Overview

Problem

Current electrophotographic image forming apparatuses face challenges in achieving high-quality image formation with low-temperature fixation properties and storage stability while minimizing odor generation, and they often require complex and costly designs to achieve high-speed printing.

Innovation Solution

The use of a toner with a binder resin comprising a polyester resin obtained by condensation polymerization of an alcohol component and a carboxylic acid component containing (meth)acrylic acid modified rosin, which provides excellent low-temperature fixation properties, storage stability, and reduced odor, along with a charging unit that uniformly charges the latent electrostatic image bearing member without contact and a developing unit with a magnetic field generating developer bearing member.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a tandem system with multiple image forming elements is used to achieve high-speed printing, then productivity is improved, but device complexity and cost increase

Engineering Contradiction:
Improveprinting speedVSAvoidapparatus size
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent divides the image forming apparatus into multiple independent image forming elements (first, second, third, and fourth image forming elements), each capable of forming monochrome images. This segmentation allows parallel processing of multiple images simultaneously, achieving high-speed printing while keeping each individual element simple and manageable.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each image forming element is designed with universal components (charging unit, developing unit, transferring unit, cleaning unit) that can perform all necessary image formation functions. This multi-functionality allows the system to achieve high productivity through parallel processing while avoiding the need for specialized complex components in each element.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Device complexity

If down-sizing of the image forming apparatus is pursued to reduce cost and size, then device complexity is reduced, but it becomes difficult to impart high performances and enhance stability to each unit

Engineering Contradiction:
Improveapparatus sizeVSAvoidunit stability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent optimizes key parameters of the toner composition, specifically setting the polyester content to 30-70 wt% and the glass transition temperature to -50°C to 0°C. These parameter changes enable the toner to maintain stable properties at reduced sizes while achieving reliable low-temperature fixation and preventing abnormalities such as density decrease and background smear.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite toner material consisting of polyester (30-70 wt%), vinylidene fluoride (20-70 wt%), and vinyl fluoride (5-30 wt%). This composite material combines the advantages of different polymers to achieve both low-temperature fixation and high stability, allowing down-sized apparatus to maintain high performance and reliability.

Inventive Principle:
Principle #40Composite materials

3Use of energy by moving object

If low-temperature fixation is implemented to save energy and improve efficiency, then use of energy is reduced, but fixation quality and image stability may deteriorate

Engineering Contradiction:
Improvefixation temperatureVSAvoidfixation quality
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the toner by incorporating specific ratios of polyester (30-70 wt%), vinylidene fluoride (20-70 wt%), and vinyl fluoride (5-30 wt%), along with controlling the glass transition temperature (-50°C to 0°C). These parameter changes enable the toner to achieve reliable fixation at low temperatures without sacrificing image quality or stability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite toner material combining polyester, vinylidene fluoride, and vinyl fluoride in specific proportions. This composite material provides both low-temperature fixation capability and high fixation quality, allowing energy-saving operations while maintaining reliable image formation and preventing abnormalities such as density decrease and background smear.

Inventive Principle:
Principle #40Composite materials

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 solution enables the formation of high-quality images with consistent fixation properties and extended color tone stability, reducing the occurrence of abnormalities like density decrease or background smear, while also simplifying the apparatus design and reducing costs.

Implementation Method 1

a charging unit configured to charge a surface of the latent electrostatic image bearing member

Methodology Applied
Scientific EffectElectrostatic charging: Electrostatics

Implementation Method 2

an exposing unit configured to expose the charged surface of the latent electrostatic image to form a latent electrostatic image thereon

Methodology Applied
Scientific EffectPhotoconductivity: Photoconductivity

Implementation Method 3

a developing unit configured to develop the latent electrostatic image with a toner to form a visualized image

Methodology Applied
Scientific EffectElectrostatic attraction: Electrostatics

Implementation Method 4

a transferring unit configured to transfer the visualized image onto a recording medium

Methodology Applied
Scientific EffectElectrostatic transfer: Electrostatics

Implementation Method 5

the visualized image thus transferred is fixed to the medium by application of heat and/or pressure

Methodology Applied
Scientific EffectThermal heating: Heating

Data Source

PatentEP2010968B1Image forming apparatus, image forming method, and process cartridge
Publication Date: 2014.09.03 RICOH CO LTD
  • EP2010968B1 patent drawingFigure 1~2
  • EP2010968B1 patent drawingFigure 3~4
  • EP2010968B1 patent drawingFigure 5~6

AI summary

To provide an image forming apparatus including: a latent electrostatic image bearing member; a charging unit configured to charge the surface of the latent electrostatic image bearing member; an exposing unit configured to expose the charged surface of the latent electrostatic image to form a latent electrostatic image; a developing unit configured to develop the latent electrostatic image with a toner to form a visualized image; a transferring unit configured to transfer the visualized image onto a recording medium; and a fixing unit configured to fix the transferred image transferred onto the recording medium, wherein the toner comprises a binder resin and a coloring agent, and the binder resin comprises a polyester resin obtained by condensation polymerization of an alcohol component and a carboxylic acid component containing a (meth)acrylic acid modified rosin.