Carrier Resins with Ester and Nitrogen Groups for Charge Control
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Solution Overview
Problem
Current carrier coatings for toners face challenges in achieving high triboelectric charge and relative humidity (RH) sensitivity, often resulting in low or incorrect toner charge due to the use of silica additives, which are RH sensitive and can compromise resin hardness and glass transition temperature (Tg) when nitrogen-containing compounds are introduced.
Innovation Solution
A carrier coating comprising monomers with ester functional groups and cyclic aliphatic groups containing nitrogen atoms, which enhances charge transfer and RH sensitivity while maintaining resin hardness and Tg, using acrylates and methacrylates as suitable monomers and incorporating nitrogen-containing moieties like N-alkyl piperidinyl or amide groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If smaller-sized silica particles are used as external additives to achieve high triboelectric charge, then charge increases, but developability at low toner area coverage degrades over time
Solution Approach 1:
The patent extracts the problematic smaller-sized silica particles from the toner formulation and replaces them with larger-sized silica particles (average size of 20 nm or more), thereby removing the source of the developability degradation while maintaining the charge enhancement benefit
Solution Approach 2:
The patent changes the particle size parameter of silica additives from smaller sizes (less than 20 nm) to larger sizes (20 nm or more), which fundamentally alters the tribological behavior and prevents the additives from impacting into the toner surface over time
2Reliability
If larger-sized silica particles are used to maintain developability, then developability is preserved, but triboelectric charge decreases and charge through occurs
Solution Approach 1:
The patent creates a composite carrier coating system combining silicon oxide particles (0.1-10 μm) with a polymer matrix containing nitrogen-containing groups, where the polymer component compensates for the reduced charge of larger silica particles while the silica maintains developability
Solution Approach 2:
The carrier coating is designed to perform multiple functions simultaneously: the polymer matrix provides high charge through nitrogen-containing groups while the larger silica particles maintain developability, creating a multi-functional system that addresses both requirements
3Use of energy by moving object
If nitrogen-containing compounds are added to increase charge, then triboelectric charge improves, but resin hardness and glass transition temperature decrease
Solution Approach 1:
The patent carefully controls the molecular weight, concentration, and chemical structure parameters of nitrogen-containing compounds to achieve optimal charge while minimizing the softening effect on the resin matrix
Solution Approach 2:
The nitrogen-containing groups are distributed throughout the polymer matrix to provide charge enhancement at specific locations without uniformly compromising the overall resin hardness and structural integrity
4Use of energy by moving object
If nitrogen-containing compounds are added to increase charge, then triboelectric charge improves, but relative humidity sensitivity worsens
Solution Approach 1:
The patent optimizes the hydrophobicity parameter of nitrogen-containing compounds by selecting appropriate alkyl chain lengths and structures, reducing their affinity for water vapor and thereby minimizing RH sensitivity while maintaining charge enhancement
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 provides toners with improved triboelectric charge and RH sensitivity, maintaining resin hardness and Tg, thus addressing the limitations of existing carrier coatings by optimizing charge transfer and environmental sensitivity.
Implementation Method 1
Toners having triboelectric charge within the range of about −30 μC/g to about −45 μC/g may be achieved by including smaller-sized silica particles as external additives
Implementation Method 2
The nitrogen containing groups have been shown by modeling to have a much lower barrier to charge transfer than the best performing conventional resins, especially with silica as a toner additive on the toner
Data Source
AI summary
The disclosure generally describes carrier resins, and in particular, resins used for carrier coatings which include at least one ester functional group and at least one cyclic aliphatic group containing at least one nitrogen atom in the cyclic ring structure. Carriers having such resins in the coating exhibit high charge and excellent relative humidity (RH) sensitivity of charge to changing environmental conditions.