Toner Resin Composition for Low-Temperature Fixing and Hot-Offset Resistance
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Solution Overview
Problem
Existing toners for electrophotographic image formation face challenges in achieving low-temperature fixing properties, heat-resistant storage stability, and hot-offset resistance, particularly at high speeds, due to limitations in resin composition and molecular structure, leading to issues like rough image surfaces and decreased image density.
Innovation Solution
A toner formulation incorporating a combination of crystalline polyester resin, non-crystalline resin, and composite resin, with specific molecular weight distributions and softening temperatures, to enhance low-temperature fixing, heat-resistant storage stability, and hot-offset resistance, while maintaining electrical resistance and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the glass transition temperature (Tg) of the resin is lowered to improve low-temperature fixing property, then the fixing temperature can be reduced, but the heat-resistant storage stability is degraded
Solution Approach 1:
The patent employs a composite resin system comprising multiple components: a polyester resin with specific Tg (80-120°C), a styrene-acrylic resin, and a non-olefin crystalline polymer. This composite structure allows the polyester resin to provide low-temperature fixing capability while the other components maintain heat-resistant storage stability and prevent hot offset, resolving the contradiction between low fixing temperature and storage stability.
Solution Approach 2:
The patent optimizes the molecular weight and molecular weight distribution of the polyester resin, specifying a weight-average molecular weight of 5,000-20,000 and a polydispersity index of 1.05-2.0. By precisely controlling these parameters, the resin achieves appropriate Tg for low-temperature fixing while maintaining sufficient heat-resistant storage stability.
2Temperature
If the softening temperature (T1/2) is lowered by reducing molecular weight to improve low-temperature fixing, then the fixing temperature can be reduced, but hot offset occurs
Solution Approach 1:
The patent uses a composite resin system where the polyester resin provides low-temperature fixing capability, while the styrene-acrylic resin and non-olefin crystalline polymer work together to prevent hot offset. The non-olefin crystalline polymer with melting point 60-100°C specifically contributes to preventing hot offset while allowing low-temperature fixing.
Solution Approach 2:
The patent specifies precise molecular weight parameters for the polyester resin (weight-average molecular weight 5,000-20,000, polydispersity index 1.05-2.0) to achieve the optimal balance between low-temperature fixing capability and hot offset resistance, preventing premature softening at high temperatures.
3Productivity
If system speed is increased to improve productivity, then the image forming speed increases, but the fixing performance deteriorates due to insufficient heat absorption
Solution Approach 1:
The patent modifies the thermal characteristics of the toner by using polyester resin with specific Tg (80-120°C) and molecular weight parameters, enabling the toner to fix at lower temperatures. This allows the fixing process to occur more quickly, matching high-speed image formation without sacrificing fixing quality.
Solution Approach 2:
The composite resin system in the toner formulation provides both low-temperature fixing capability and sufficient heat-resistant storage stability, allowing rapid fixing at high system speeds while preventing defects like rough surfaces and cold offset that would otherwise occur.
4Reliability
If the fixing temperature is increased to maintain image quality at high speed, then the fixing performance is maintained, but energy consumption increases and fixing member wearing accelerates
Solution Approach 1:
The patent changes the thermal parameters of the toner resin to achieve low-temperature fixing (Tg 80-120°C), which directly reduces the fixing temperature required. This lowers energy consumption in the fixing process and reduces thermal stress on the fixing member, decreasing wearing speed.
Solution Approach 2:
The composite resin system provides the optimal balance of low-temperature fixing capability and heat-resistant storage stability, enabling quality image formation at reduced temperatures, thereby saving energy and reducing fixing member wear compared to conventional high-temperature fixing.
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 proposed toner achieves exceptional low-temperature fixing, high hot-offset resistance, and favorable storage stability, ensuring high-quality image formation over a long period with improved molecular dispersion and resistance to thermal degradation.
Implementation Method 1
a crystalline polyester resin (A); a non-crystalline resin (B); a non-crystalline resin (C); and a composite resin (D) which includes a condensation polymerization resin unit and an addition polymerization resin unit
Implementation Method 2
use of a polyester resin which has superior low-temperature fixing property... a crystalline polyester resin (A)... a non-olefin crystalline polymer in a resin, where the polymer has a sharp-melting property at a glass transition temperature of the resin
Implementation Method 3
a technology to form a sea-island phase-separation structure of a crystalline polyester and a non-crystalline polyester, which are incompatible with each other
Implementation Method 4
a composite resin (D) which includes a condensation polymerization resin unit and an addition polymerization resin unit
Implementation Method 5
a composite resin (D) which includes a condensation polymerization resin unit and an addition polymerization resin unit
Data Source
AI summary
A toner for forming an electrophotographic image is provided, wherein the toner includes at least four types of binder resins,wherein the binder resins includes at least:a crystalline polyester resin (A);a non-crystalline resin (B);a non-crystalline resin (C); anda composite resin (D) which includes a condensation polymerization resin unit and an addition polymerization resin unit,wherein the non-crystalline resin (B) includes a chloroform insoluble matter,wherein the non-crystalline resin (C) has a softening temperature (T½) lower than that of the non-crystalline resin (B) by 25° C. or more, andwherein the toner has a main peak between 1,000 to 10,000 in a molecular weight distribution obtained by GPC from a tetrahydrofuran soluble matter, and the toner has a half-value width of the molecular weight distribution of 15,000 or less.