Core-Shell Toner Resin for Electrophotography
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Solution Overview
Problem
Toners for electrophotography face challenges in achieving both good heat-resistant storage properties and low-temperature fusing properties, as these properties are often contradictory, and existing core-shell structures with crystalline polyester can compromise durability.
Innovation Solution
A toner with a core-shell structure where the core portion contains an amorphous resin with a softening point of 105°C or lower, obtained by polycondensing alkenyl succinic acid with an alcohol component, and the shell portion contains an amorphous resin polycondensed with an aliphatic diol and a trivalent or higher-valent polycarboxylic acid compound in limited amounts, enhancing compatibility and maintaining the core-shell structure for improved durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a core-shell structure with crystalline polyester is used, then low-temperature fusing property is improved, but heat-resistant storage property deteriorates
Solution Approach 1:
The invention applies local quality by creating a core-shell structure where the core portion contains crystalline polyester for low-temperature fusing, while the shell portion contains amorphous resin with specific softening point (105°C or lower) for heat-resistant storage. This spatial differentiation of material properties resolves the contradiction between low-temperature fusing and heat-resistant storage by assigning different functional characteristics to different regions of the same particle.
Solution Approach 2:
The invention uses composite materials by combining crystalline polyester in the core with amorphous resin containing specific carboxylic acid components (alkyl succinic acid, alkenyl succinic acid, or alkyl alkenyl succinic acid) in the shell. This composite structure allows the toner to simultaneously achieve low-temperature fusing property from the crystalline core and heat-resistant storage property from the amorphous shell with controlled softening characteristics.
2Temperature
If compatibility between amorphous resin and crystalline polyester is enhanced, then low-temperature fusing property is improved, but durability deteriorates
Solution Approach 1:
The invention applies parameter changes by carefully controlling the softening point of the amorphous resin in the shell to be 105°C or lower, and limiting the content of trivalent or higher-valent polycarboxylic acid compounds to 20 mol% or less. These parameter optimizations ensure sufficient compatibility with crystalline polyester for low-temperature fusing while preventing excessive compatibility that would compromise durability and heat-resistant storage property.
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 results in a toner that excels in heat-resistant storage, low-temperature fusing, and durability, maintaining the core-shell structure's effectiveness while minimizing the production of low-molecular weight components that could compromise compatibility.
Implementation Method 1
an amorphous resin (A) having a softening point of 105° C. or lower which is obtained by polycondensing a carboxylic acid component containing an alkenyl succinic acid with an alcohol component
Implementation Method 2
a shell portion containing an amorphous resin (B) obtained by polycondensing an alcohol component containing an aliphatic diol having 2 to 6 carbon atoms with a carboxylic acid component containing a trivalent or higher-valent polycarboxylic acid compound
Implementation Method 3
a toner for electrophotography including core-shell particles as a resin binder each including a core portion containing an amorphous resin (A) having a softening point of 105° C. or lower
Data Source
AI summary
The present invention relates to a toner for electrophotography including core-shell particles as a resin binder each including a core portion containing an amorphous resin (A) having a softening point of 105° C. or lower which is obtained by polycondensing a carboxylic acid component containing an alkenyl succinic acid with an alcohol component; and a shell portion containing an amorphous resin (B) obtained by polycondensing an alcohol component containing an aliphatic diol having 2 to 6 carbon atoms with a carboxylic acid component containing a trivalent or higher-valent polycarboxylic acid compound in an amount of 20 mol % or less. The toner for electrophotography according to the present invention is excellent in heat resistant storage property, low-temperature fusing property and durability.