Toner Binder Resin Low-Temperature Fixation

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Solution Overview

Problem

Current image forming apparatuses face challenges in achieving high-quality images with low-temperature fixation properties, anti-offset properties, storage stability, and filming resistance, while also reducing odor generation and preventing abnormalities like density decrease or background smear, especially during high-speed continuous printing.

Innovation Solution

The use of a toner comprising a binder resin with a combination of polyester-based resins (A) and (B), where resin (A) is derived from (meth)acrylic acid-modified rosin and resin (B) from fumaric acid/maleic acid-modified rosin, both having melting and softening points at least 10°C higher than resin (A), enhancing molecular weight and crosslinking for improved fixation and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single latent electrostatic image bearing member is used with 4 developing units, then the apparatus size and cost are reduced, but the image formation speed decreases

Engineering Contradiction:
Improveapparatus sizeVSAvoidimage formation speed
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The patent divides the image forming system into multiple independent image forming elements, each with its own latent electrostatic image bearing member and developing units. This segmentation allows parallel processing of different colors, enabling high-speed full-color image formation while keeping each individual element compact and cost-effective.

Inventive Principle:
Principle #1Segmentation

2Productivity

If multiple latent electrostatic image bearing members are used for parallel processing, then image formation speed increases, but the apparatus size increases

Engineering Contradiction:
Improveimage formation speedVSAvoidapparatus size
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent employs a compact modular design where multiple image forming elements are arranged in a space-efficient configuration. Each element is designed as an integrated module with nested components, allowing parallel processing capability while minimizing the overall apparatus footprint through efficient spatial arrangement.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Device complexity

If down-sizing of image forming elements is performed, then apparatus size and material cost are reduced, but high performance and stability of each unit become more difficult to achieve

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

Solution Approach 1:

The patent optimizes critical parameters of the down-sized image forming elements, including the electrical and mechanical properties of the latent electrostatic image bearing members and developing units. Through precise parameter control and optimization, the invention achieves high performance and stability in compact configurations, resolving the trade-off between size reduction and reliability maintenance.

Inventive Principle:
Principle #35Parameter changes

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 extremely high-quality images with excellent low-temperature fixation, anti-offset, and storage stability, reducing odor and preventing image abnormalities, even during long-term use and high-speed printing.

Implementation Method 1

the surface of a latent electrostatic image bearing member (hereinafter sometimes referred to as a 'photoconductor,' an 'electrophotoconductor' or an 'image bearing member') is charged

Methodology Applied
Scientific EffectElectrostatic charging: Electrostatics

Implementation Method 2

the charged surface is then exposed to form a latent electrostatic image thereon

Methodology Applied
Scientific EffectPhotoconductivity: Photoconductivity

Implementation Method 3

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

Methodology Applied
Scientific EffectThermal heating: Heating

Implementation Method 4

the binder resin comprises a polyester-based resin (A) and a polyester-based resin (B) having a melting point which is at least 10°C higher than that of the polyester-based resin (A)

Methodology Applied
Scientific EffectMelting: Melting

Data Source

PatentEP1862864B1Image forming apparatus, image forming method and process cartridge including a toner
Publication Date: 2012.05.30 RICOH CO LTD
  • EP1862864B1 patent drawingFigure 1~2
  • EP1862864B1 patent drawingFigure 3~4
  • EP1862864B1 patent drawingFigure 5~6

AI summary

To provide an image forming apparatus including a latent electrostatic image bearing member; a charging unit; an exposing unit; a developing unit; a transferring unit; and a fixing unit, wherein the binder resin of a toner comprises a polyester-based resin (A) and a polyester-based resin (B) having a melting point which is at least 10°C higher than that of the polyester-based resin (A), the polyester-based resins (A) is a resin which is derived from a (meth)acrylic acid-modified rosin and which has a polyester unit obtained by condensation polymerization of an alcohol component and a carboxylic acid component containing a (meth)aciylic acid-modified rosin, and the polyester-based resin (B) is a resin derived from a fumaric acid/maleic acid-modified rosin and has a polyester unit obtained by condensation polymerization of an alcohol component and a carboxylic acid component containing any one of a fumaric acid-modified rosin and a maleic acid-modified rosin.