Electrophotographic Developer Set with Crystalline Polyester Resin
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Solution Overview
Problem
Existing electrophotographic developer sets face challenges in achieving both sufficient adhesive strength and hot offset resistance when forming images and adhesive portions on paper bags, as previous methods either fail to provide adequate adhesion or result in hot offset issues due to temperature-related deformations.
Innovation Solution
An electrophotographic developer set comprising a toner and a powder adhesive, where the powder adhesive includes a crystalline polyester resin and a thermoplastic resin, with a crystalline polyester resin content of 21% or more, a melting point between 55°C to 100°C, and specific viscoelastic properties to ensure adequate adhesive strength and hot offset resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the adhesive portion is heated and melted at a high temperature to obtain adhesive strength, then adhesive strength is improved, but hot offset occurs and the image portion melts and transfers to the fixing unit
Solution Approach 1:
The patent changes the physical and chemical parameters of the powder adhesive by specifying a melting point range of 55°C to 100°C and controlling the storage elastic modulus ratio (Gt'(100)/Gb'(100) ≥ 1.2). These parameter changes enable the adhesive to melt at lower temperatures sufficient for bonding while preventing the image toner from melting and causing hot offset.
Solution Approach 2:
The patent uses a composite powder adhesive system comprising crystalline polyester resin (21% or more by mass) combined with other thermoplastic resins. This composite material structure provides both the necessary adhesive strength through controlled melting and the thermal stability to prevent hot offset of the image portion.
2Temperature
If a lower limit temperature of appropriate fixing temperature of the adhesive toner is made lower than that of a toner used for image formation, then the adhesive toner can be melted at a temperature at which the toner used for image formation is not melted, but sufficient adhesive strength may not be obtained
Solution Approach 1:
The patent optimizes multiple parameters simultaneously: melting point (55°C to 100°C), crystalline polyester resin content (21% or more by mass), and storage elastic modulus ratio (Gt'(100)/Gb'(100) ≥ 1.2). This multi-parameter optimization ensures that the adhesive melts at a lower temperature than image toner while achieving sufficient adhesive strength through the controlled viscoelastic properties.
Solution Approach 2:
The patent utilizes the phase transition properties of the crystalline polyester resin, which melts within a specific temperature range (55°C to 100°C). This controlled phase transition enables the adhesive to change from solid to liquid state at temperatures below image toner melting points, facilitating bonding without compromising adhesive strength.
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 developer set effectively achieves both sufficient adhesive strength for paper bonding and resistance to hot offset, ensuring the integrity of the paper bag formation process by controlling the melt viscosity and storage elastic modulus of the powder adhesive and toner.
Implementation Method 1
the melting point of the crystalline polyester resin is 55° C. to 100° C.
Implementation Method 2
in a viscoelasticity measurement, where Gt′(100) denotes a storage elastic modulus of the toner at 100° C. and Gb′(100) denotes a storage elastic modulus of the powder adhesive at 100° C.
Data Source
AI summary
An electrophotographic developer set comprising a toner, and a powder adhesive, wherein the powder adhesive comprises a crystalline polyester resin, and a thermoplastic resin other than the crystalline polyester resin; the amount of the crystalline polyester resin in the powder adhesive is 21% by mass or more; the melting point of the crystalline polyester resin is 55° C. to 100° C.; in a viscoelasticity measurement, where Gt′(100) denotes a storage elastic modulus of the toner at 100° C. and Gb′(100) denotes a storage elastic modulus of the powder adhesive at 100° C., Gb′(100) is 1.0×105 Pa or less and Gt′(100)/Gb′(100) is 1.2 or more.