Silicone Release Layer Molecular Weight for Digital Offset Printing
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Solution Overview
Problem
In digital offset printing, intermediate transfer members (ITMs) with silicone release layers are prone to chemical and thermal degradation due to continuous exposure to carrier liquids and repeated heating and cooling cycles, leading to deteriorated ink transfer quality and the need for frequent ITM replacement.
Innovation Solution
The use of a cured silicone release layer formed by curing a curable silicone release formulation containing a polyalkylsiloxane with a weight average molecular weight of at least 65,000 g/mol, a polyalkylsiloxane cross-linker with Si—H bonds, and a catalyst or photoinitiator, which enhances the durability of the release layer without compromising mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional silicone release layers are used (formed by condensation curing or thermally assisted addition curing), then the ITM can be manufactured with standard processes, but the release layer deteriorates due to chemical and thermal degradation from carrier liquid exposure and heating/cooling cycles
Solution Approach 1:
The patent changes the molecular weight parameter of the polyalkylsiloxane from conventional lower values to at least 65,000 g/mol, and specifies a particular Si-H bond content range (0.5-2.0 mmol/g). These parameter changes result in a cured silicone release layer with significantly improved resistance to chemical degradation from carrier liquids and thermal degradation from heating/cooling cycles, thereby extending ITM lifespan while maintaining manufacturing feasibility
Solution Approach 2:
The patent creates a composite curing system combining polyalkylsiloxane with Si-H bonds and specific crosslinkers (such as polyalkylene glycol or organometallic compounds). This composite material approach produces a cured release layer with enhanced network structure that resists both chemical attack from carrier liquids and thermal stress from repeated heating/cooling, resolving the contradiction between durability and lifespan
2Reliability
If the polyalkylsiloxane molecular weight is increased to at least 65,000 g/mol to improve durability, then chemical and thermal degradation is reduced, but the formulation complexity increases
Solution Approach 1:
The patent establishes specific parameter ranges to balance performance and simplicity: polyalkylsiloxane molecular weight of at least 65,000 g/mol, Si-H bond content of 0.5-2.0 mmol/g, and crosslinker content of 1-20 parts by weight per 100 parts polyalkylsiloxane. These quantified parameters provide a straightforward formulation specification that achieves superior durability without excessive complexity
Solution Approach 2:
The patent focuses the complexity enhancement specifically in the polyalkylsiloxane molecular weight and crosslinking structure, while keeping other formulation aspects simple and conventional. This localized quality improvement allows the release layer to achieve superior degradation resistance without making the entire formulation overly complex
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
This solution significantly reduces the deterioration of the release layer, thereby improving the long-term print quality and extending the lifespan of the ITM by mitigating chemical and thermal degradation, thus reducing the frequency of ITM replacement.
Implementation Method 1
a cured silicone release layer formed by curing a curable silicone release formulation comprising: a polyalkylsiloxane containing at least two vinyl groups having a weight average molecular weight of 60,000 g/mol or less; a polyalkylsiloxane containing two vinyl groups having a weight average molecular weight of at least 65,000 g/mol; a polyalkylsiloxane cross-linker containing at least two Si—H bonds; and a catalyst or a photoinitiator
Data Source
AI summary
There is described an intermediate transfer member for digital offset printing, comprising: a cured silicone release layer formed by curing a curable silicone release formulation comprising: a polyalkylsiloxane containing at least two vinyl groups having a weight average molecular weight of 60,000 g/mol or less; a polyalkylsiloxane containing two vinyl groups having a weight average molecular weight of at least 65,000 g/mol; a polyalkylsiloxane cross-linker containing at least two Si—H bonds; and a catalyst or a photoinitiator. There is also described a method of producing an intermediate transfer member, and a curable silicone release formulation for an intermediate transfer member.