Toner Resin Composition for Hot Offset and Low-Temperature Fixing
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Solution Overview
Problem
Toners for electrostatic imaging face a challenge in balancing hot offset and low-temperature fixing properties, as existing solutions tend to be mutually contradictory, requiring improvement for speed and energy efficiency.
Innovation Solution
A polyester resin for toners with specific molecular weight, acid value, hydroxyl value, and THF-insoluble fraction content, combined with a colorant and optional additives like mold release agents, charge control agents, and fluidizing agents, to achieve enhanced hot offset and low-temperature fixing properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a toner is designed to have high hot offset property (resistance to fusing at high temperatures), then the low-temperature fixing property deteriorates (cannot be fixed at low temperatures)
Solution Approach 1:
The resin is segmented into multiple functional components with distinct roles: polyester resin (A) provides hot offset resistance through its THF-insoluble fraction, while polyester resin (B) enables low-temperature fixing through its low glass transition temperature. This segmentation allows each component to independently contribute to its specialized function without interfering with the other.
Solution Approach 2:
The invention uses a composite resin system combining polyester resin (A) and polyester resin (B) in specific proportions (70/30 to 95/5 by weight). This composite material integrates the high-temperature stability of resin (A) with the low-temperature flexibility of resin (B), achieving both hot offset property and low-temperature fixing capability simultaneously.
2Reliability
If the glass transition temperature of the resin is increased to improve hot offset property, then the low-temperature fixing property worsens
Solution Approach 1:
The resin system is segmented into two components with different glass transition temperatures: polyester resin (A) with Tg of 80°C or higher for hot offset resistance, and polyester resin (B) with Tg of -50°C to 50°C for low-temperature fixing. This segmentation resolves the contradiction by assigning different thermal characteristics to different functional roles.
Solution Approach 2:
The invention changes the parameter of glass transition temperature distribution by using multiple resin components instead of a single resin with a fixed Tg. This allows the toner to exhibit appropriate viscosity and flow characteristics at both high and low temperatures, improving both hot offset property and fixing efficiency.
3Reliability
If the resin composition is optimized for hot offset property, then the anti-blocking property and gloss generating property deteriorate
Solution Approach 1:
The composite resin system maintains proper balance between hot offset property and anti-blocking property through the synergistic combination of polyester resin (A) and polyester resin (B). The specific weight ratio range (70/30 to 95/5) ensures that the resin has appropriate viscosity and flow characteristics that prevent toner particles from adhering to each other while maintaining high-temperature stability.
Solution Approach 2:
The invention optimizes the parameter of resin composition by controlling the weight ratios of polyester resin (A) and (B), along with their respective molecular weights and glass transition temperatures. This parameter optimization achieves a balance between hot offset resistance, anti-blocking property, and gloss generating capability.
Data Source
AI summary
The object is to develop a resin for a toner, which has both of hot offset resistance and a low-temperature fixing property even when used in a high-speed and energy-saving toner. Thus, disclosed is a resin for a toner, which comprises a polyester resin (A) having a THF insoluble fraction content of 1 to 36 wt %, a peak top molecular weight of 4500 to 20000 as measured by gel permeation chromatography on a THF soluble fraction, and a softening point of 120 to 180° C., and meeting the requirements represented by the following formulae (1) and (2):(Acid value)/(hydroxyl value)≧1 (acid value=15 to 80 mgKOH/g, hydroxyl value≧3.0 mgKOH/g) Formula (1)(A numeric value of the THF-insoluble fraction content expressed in % by weight)/(a numeric value of the softening point expressed in degree ° C.)≦0.2 Formula (2).