Electrophotographic Toner Binder Using Acrylate Solubility Parameters
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Solution Overview
Problem
Conventional electrophotographic toner binders face challenges in achieving simultaneous low-temperature fixability, hot-offset resistance, and storage stability, with polyester-based binders suffering from poor charging characteristics and high production costs, while polymer-based binders derived from ethylenically unsaturated monomers lack sufficient intermolecular cohesive force.
Innovation Solution
A polymer binder is developed using a combination of (meth)acrylates with C18-C36 acyclic hydrocarbon groups and other monomers, specifically designed to satisfy a solubility parameter relational expression, which enhances the binder's properties without requiring polycondensation reactions, allowing for production via emulsion polymerization or suspension polymerization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polyester is used as the main component of the toner binder, then the intermolecular cohesive force is improved, but the charging characteristics deteriorate due to decreased volume resistivity from moisture absorption
Solution Approach 1:
The invention uses a composite polymer system consisting of a polycondensation polymer component (providing cohesive force) and a polymer component derived from ethylenically unsaturated monomers (providing high volume resistivity and good charging characteristics). This composite approach combines the advantages of both material types to achieve both strong intermolecular cohesive force and excellent charging characteristics.
2Reliability
If a polymer derived from a monomer having an ethylenically unsaturated bond is used as the main component, then the charging characteristics are improved, but the intermolecular cohesive force deteriorates, failing to provide low-temperature fixability and hot-offset resistance
Solution Approach 1:
The invention combines a polymer component derived from ethylenically unsaturated monomers (providing good charging characteristics and high volume resistivity) with a polycondensation polymer component (providing strong intermolecular cohesive force). This composite structure enables the toner binder to simultaneously achieve excellent charging characteristics and sufficient intermolecular cohesive force for low-temperature fixability and hot-offset resistance.
Solution Approach 2:
The invention specifies precise compositional parameters: the polycondensation polymer component comprises 30-70 mass% of the total binder, and the polymer component derived from ethylenically unsaturated monomers comprises 30-70 mass% of the total binder. This parameter control optimizes the balance between cohesive force and charging characteristics.
3Temperature
If a crystalline acrylate resin is used to improve low-temperature fixability, then the melting properties are improved, but the storage stability deteriorates due to lower melting point from inhibited crystallinity when acid value is added
Solution Approach 1:
The invention carefully controls the acid value parameter of the crystalline acrylate resin to be within 0-50 meq/kg, and optimizes the compositional ratio of the polycondensation polymer component (30-70 mass%). This parameter optimization maintains the crystallinity and melting properties necessary for low-temperature fixability while preventing excessive acidification that would inhibit crystallinity and reduce storage stability.
4Strength
If a combination of crystalline acrylate resin and crosslinking agent is used to improve hot-offset resistance, then the cohesive force is improved, but the viscosity increases and low-temperature fixability deteriorates
Solution Approach 1:
The invention uses a composite system of polycondensation polymer and ethylenically unsaturated polymer components, which provides hot-offset resistance through strong intermolecular cohesive force without requiring crosslinking agents. This approach avoids the viscosity increase and loss of low-temperature fixability that result from crosslinking.
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 resulting toner binder exhibits excellent low-temperature fixability, hot-offset resistance, and storage stability, while being cost-effective and applicable to both pulverized and chemical toners.
Implementation Method 1
a polymer component derived from ethylenically unsaturated monomers... production via emulsion polymerization or suspension polymerization
Data Source
AI summary
The present invention provides an electrophotographic toner binder containing, as a main component, a polymer whose constituent monomer is a monomer having an ethylenically unsaturated bond, the electrophotographic toner binder being excellent in low-temperature fixability, hot-offset resistance, and storage stability. The present invention provides an electrophotographic toner binder containing a polymer (A) containing a monomer (a) and a monomer (x) different from the monomer (a) as essential constituent monomers, wherein the monomer (a) is a (meth)acrylate having a C18-C36 acyclic hydrocarbon group, the polymer (A) has an acid value of 40 or less, and the polymer (A) satisfies the following relational expression (1):1.1 (cal/cm3)0.5≤|SP(x)−SP(a)|≤8.0 (cal/cm3)0.5 relational expression (1):wherein SP(a) is the SP value of a structural unit derived from the monomer (a) constituting the polymer (A); andSP(x) is the SP value of a structural unit derived from the monomer (x) different from the monomer (a) constituting the polymer (A).