Toner Binder Resin Composition for Fixing and Offset
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Solution Overview
Problem
Conventional toner binders fail to achieve a balance between low-temperature fixability, hot offset resistance, storage stability, electrostatic charging properties, and grindability, often compromising on one or more of these aspects due to conflicting relationships between molecular weight, cross-linking, and the use of external additives.
Innovation Solution
A toner binder comprising a polyester resin with an acid value of 5 to 25 mg KOH/g and a vinyl resin with a weight average molecular weight of 4,000 to 40,000, specifically designed to have a monomer with an SP value of 11.5 to 16.5, and a weight ratio of 80/20 to 99.5/0.5, without polyethylene or polypropylene units, to enhance productivity and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the molecular weight of toner binder is increased or cross-linked structure is introduced to improve hot offset resistance, then hot offset resistance is improved, but grindability is significantly reduced and productivity decreases
Solution Approach 1:
The invention changes the chemical composition parameters of the toner binder by using a specific polyester resin with controlled acid value (5-50 mg KOH/g) and combining it with a vinyl resin having specific glass transition temperature (0°C to 100°C). This parameter optimization allows achieving hot offset resistance without requiring high molecular weight or cross-linked structures that would harm grindability.
Solution Approach 2:
The invention creates a composite binder system by combining polyester resin (providing hot offset resistance) with vinyl resin (providing grindability and low-temperature fixability). This composite approach allows each component to contribute its strengths without the drawbacks of using single high-performance materials, thus resolving the contradiction between hot offset resistance and grindability.
2Productivity
If external additives such as fluidizer are added in large amounts to improve grindability, then grindability is improved, but fixing performance is impaired due to additive mixing into toner
Solution Approach 1:
The invention extracts the grindability-enhancing function from external additives and transfers it to the binder resin itself by optimizing the vinyl resin content (5-50 wt%). This eliminates the need for large amounts of external fluidizers that would contaminate the toner and harm fixing performance, while still achieving excellent grindability through the modified binder composition.
3Productivity
If conventional grinding aids are used to improve grindability, then grindability is improved, but fixing performance, storage stability, and electrostatic charging properties are impaired
Solution Approach 1:
The vinyl resin acts as an intermediary component that mediates between the polyester resin (providing hot offset resistance) and the toner particles. It transfers the grindability enhancement function to the binder system itself, eliminating the need for conventional grinding aids that would compromise fixing performance, storage stability, and electrostatic charging properties.
4Reliability
If a wide fixing temperature range is required to stabilize the fixing process, then fixing stability is improved, but low-temperature fixability is compromised
Solution Approach 1:
The invention optimizes the glass transition temperature parameter of the vinyl resin (0°C to 100°C) to enable low-temperature fixability. By controlling this parameter, the binder remains sufficiently flexible at low temperatures for easy fixing, while the polyester resin component ensures hot offset resistance, thus achieving both low-temperature fixability and fixing stability across a wide temperature range.
Data Source
AI summary
The present invention relates to a toner binder containing: a polyester resin (A); and a vinyl resin (B), wherein the polyester resin (A) has an acid value of 2 mg KOH/g or more, the vinyl resin (B) has a weight average molecular weight of 4,000 to 40,000, the vinyl resin (B) is a polymer essentially containing a monomer (m) whose homopolymer has an SP value of 11.5 to 16.5 as a constituent monomer, the weight percentage of the monomer (m) in monomers constituting the vinyl resin (B) is 1 wt% or more based on the total weight of the monomers constituting the vinyl resin (B), the polyester resin (A) and the vinyl resin (B) are present at a weight ratio (A)/(B) of 80/20 to 99.5/0.5, and when the vinyl resin (B) contains polyethylene units (C11) having a degree of polymerization of 70 to 210 and/or polypropylene units (C12) having a degree of polymerization of 70 to 210, the total weight percentage of the polyethylene units (C11) and the polypropylene units (C12) in the vinyl resin (B) is 9 wt% or less based on the weight of the vinyl resin (B).