Homogeneous Low Hardness Polyurethane Roller
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In electrophotography, polyurethane rollers with inconsistent or contaminated surfaces result in poor print quality due to issues with hardness and surface characteristics, and the use of conventional curatives leads to phase separation and defects like 'potholes', affecting the roll's performance and longevity.
Innovation Solution
The introduction of oleochemical polyol curatives, which are reacted into the polyurethane matrix, reduces hardness and improves surface uniformity, combined with a polydiene and conductive metal salts to create a roll with controlled resistivity and oxidation, preventing migration and phase separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional curatives are used to reduce polyurethane hardness, then roller compliance improves, but phase separation and surface defects (potholes) occur
Solution Approach 1:
The patent changes the chemical parameters of the curative system by using oleochemical polyols with specific molecular weights (200-2000) and functional groups, which fundamentally alters how crosslinking occurs in the polyurethane matrix. This parameter change enables reduced hardness without the phase separation problems caused by conventional curatives
Solution Approach 2:
The patent creates a composite curative system combining oleochemical polyols with specific functional groups (carboxyl, hydroxyl, amino) that work synergistically to provide both the desired compliance and surface uniformity. This composite approach integrates multiple functions into a single curative system that avoids the defects of conventional separate curative components
2Strength
If plasticizers are added to reduce roller hardness, then compliance improves, but plasticizer migration to surface causes toner coalescence
Solution Approach 1:
The patent fundamentally changes the approach to achieving compliance by using oleochemical polyols as integral curative components rather than adding separate plasticizer additives. This parameter change in the curative system provides compliance through controlled crosslinking density without the migration issues inherent in additive-based plasticization
Solution Approach 2:
The patent extracts the problematic plasticizer component from the formulation entirely and replaces its compliance-providing function with oleochemical polyol curatives that achieve softness through molecular structure and crosslinking density rather than through migratory additive plasticization
3Adaptability or versatility
If multiple curatives are used to achieve desired properties, then roller performance improves, but curative incompatibility increases causing phase separation
Solution Approach 1:
The oleochemical polyol curatives perform multiple functions simultaneously: they provide crosslinking, control hardness, ensure surface uniformity, and maintain curative compatibility. This multi-functionality eliminates the need for multiple separate curative components that would be incompatible with each other
Solution Approach 2:
The patent merges the functions of multiple curatives into a single oleochemical polyol curative system. By combining crosslinking, hardness control, and surface uniformity functions into one compatible curative system, the patent avoids the phase separation issues that arise from using multiple incompatible curatives
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 solution achieves a reduction in defects and maintains desirable hardness and compression set properties, ensuring consistent toner distribution and improved print quality over an extended period with reduced sensitivity to environmental changes.
Implementation Method 1
The oxidation of polybutadiene, in the presence of certain conductive metal salts, produces a highly resistive layer at the surface of the roll
Data Source
AI summary
This invention employs a polyol derivative of a fatty acid that is reacted into a polyurethane formed also with a urethane prepolymer, a polydiene, and optionally, a curative for cross-linking. The fatty acid moiety becomes a relatively short side chain of the polyurethane formed. In embodiments, the polyol is an ester of the fatty acid. This achieves reduction in hardness of the polyurethane with a homogeneity that provides consistent surface characteristics over an extended period desirable for use for electrophotographic development and the like when the material is used as a developer roller.