Core-Shell Toner with Polyester-Vinyl Binders for Fixability
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Solution Overview
Problem
Conventional toners with polyester resins have difficulty achieving a good balance between low temperature fixability and high temperature preservability, and often use environmentally unfriendly organic tin compounds as catalysts.
Innovation Solution
A toner composition featuring a core with a polyester resin and a shell of vinyl copolymer, where the weight ratio of the shell to the core is between 0.05 and 0.5, and the toner has a volume average particle diameter of 3 to 8 μm, enhancing both low temperature fixability and high temperature preservability while replacing organic tin compounds with more environmentally friendly catalysts like titanium or bismuth types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a binder resin with low thermal property (low melting point) is used to enable low temperature heat fixing, then low temperature fixability is improved, but high temperature preservability deteriorates causing toner blocking
Solution Approach 1:
The toner is divided into core and shell portions with different binder resin compositions. The core contains polyester resin for low temperature fixability, while the shell contains vinyl resin for high temperature preservability. This segmentation allows each portion to provide its specific function without compromising the other.
Solution Approach 2:
The invention uses a composite binder resin system combining polyester resin and vinyl resin in specific proportions (polyester 30-70 wt%, vinyl 30-70 wt%). This composite material achieves a balance between low temperature fixability (from polyester) and high temperature preservability (from vinyl), resolving the contradiction between these two properties.
2Reliability
If polyester resin is used as binder resin to achieve good combination of low temperature fixability and high temperature preservability, then preservability is improved, but durability of toner image deteriorates
Solution Approach 1:
The invention optimizes the molecular weight parameters of the binder resins. Polyester resin has molecular weight 5,000-20,000 and vinyl resin has molecular weight 30,000-100,000. These parameter adjustments ensure that the polyester provides flexibility and adhesion for durability, while the vinyl provides thermal stability for preservability.
Solution Approach 2:
The composite binder resin system combines the adhesive properties of polyester resin with the thermal stability of vinyl resin. The specific composition ratio (30-70 wt% polyester, 30-70 wt% vinyl) ensures both durability through polyester adhesion and preservability through vinyl thermal resistance.
3Temperature
If aliphatic or alicyclic polyhydric alcohol is used to prepare polyester resin for good flexibility, then low temperature fixability is improved, but durability deteriorates due to low molecular weight
Solution Approach 1:
The invention compensates for the low durability of aliphatic/alicyclic polyester resin by combining it with vinyl resin in a composite system. The vinyl resin component provides additional strength and durability, while the polyester component maintains low temperature fixability. The synergistic effect of this composite resolves the contradiction between flexibility and durability.
Solution Approach 2:
The invention carefully controls the molecular weight of the aliphatic/alicyclic polyester resin (5,000-20,000) to balance flexibility and durability. This parameter optimization, combined with the vinyl resin addition, ensures adequate durability while maintaining low temperature fixability.
Data Source
AI summary
A toner including a core including at least a colorant, a release agent and a first binder resin; and a shell located overlying the core and including at least a second binder resin, wherein the first binder resin includes a polyester resin including a unit obtained from a diol selected from the group consisting of aliphatic diols and alicyclic diols, and the second binder resin includes a vinyl copolymer, and wherein a weight ratio (S/C) of the shell (S) to the core (C) is from 0.05 to 0.5 and the toner has a volume average particle diameter of from 3 to 8 μm.