Electron Beam Cured Silicone Pressure Sensitive Adhesives
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Solution Overview
Problem
Current methods for producing silicone pressure sensitive adhesives (PSAs) face challenges in achieving low volatile organic compound (VOC) delivery and require specific functional groups for crosslinking, which can limit their applicability and introduce interference with desired end-use properties.
Innovation Solution
The method involves using nonfunctionalized polysiloxanes that are halogenated or aromatic, combined with a tackifying resin, and cured using electron beam irradiation without the need for catalysts or initiators, allowing for the creation of crosslinked silicone PSAs with reduced VOC content and broader chemistry diversity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional thermal curing methods with catalysts are used, then crosslinking can be achieved, but specific functional groups are required which limit chemistry diversity and may interfere with end-use properties
Solution Approach 1:
The patent changes the curing mechanism from thermal/catalytic to radiation-induced crosslinking. By using electron beam or UV irradiation instead of thermal processes with catalysts, the method eliminates the need for specific functional groups (vinyl, hydroxyl, carboxyl) while achieving effective crosslinking. This parameter change in the curing approach enables broader chemistry diversity including nonfunctionalized polysiloxanes.
Solution Approach 2:
The patent replaces the thermal-mechanical curing system (heat + catalyst) with a radiation-based system (electron beam or UV light). This substitution eliminates the need for chemical catalysts and specific reactive functional groups, allowing diverse silicone chemistries to be cured without interference from catalyst requirements.
2Reliability
If high molecular weight starting materials are used, then silicone PSA performance is achieved, but solvents are required to achieve coatable viscosities resulting in high VOC content
Solution Approach 1:
The patent changes the physical state and application method by using low viscosity silicone materials that can be applied as solutions or dispersions with low solvent content. The radiation curing process allows these low-viscosity materials to be crosslinked in place, achieving high molecular weight network structures without requiring high initial molecular weight materials that would need extensive solvent dilution.
Solution Approach 2:
The patent performs preliminary crosslinking through radiation curing after application but before complete solvent evaporation. This allows the adhesive to achieve its functional crosslinked structure while still containing minimal solvent, thereby reducing VOC emissions while maintaining application feasibility.
3Object-generated harmful factors
If water-based emulsion systems or liquid solventless systems are used, then VOC content is reduced, but robust performance and crosslinking are compromised
Solution Approach 1:
The patent replaces water-based emulsion systems or liquid solventless systems with radiation-cured low-viscosity silicone systems. The radiation curing mechanism (electron beam or UV) provides robust crosslinking without requiring water or large amounts of organic solvents, achieving both low VOC content and reliable crosslinked performance.
Solution Approach 2:
The patent changes the curing activation method from thermal (requiring high temperatures and catalysts) to radiation-induced (electron beam or UV). This parameter change enables effective crosslinking of low-viscosity, low-VOC formulations without compromising performance, as the radiation energy directly initiates crosslinking without needing high concentrations of catalysts or extreme thermal conditions.
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 approach enables the production of silicone PSAs with improved performance characteristics, including reduced VOC emissions and the ability to achieve crosslinking without specific functional groups, enhancing their applicability and end-use properties.
Implementation Method 1
crosslinking the nonfunctionalized polysiloxane by exposing the composition to electron beam irradiation
Data Source
Figure 1~2
AI summary
Methods of preparing silicone pressure sensitive adhesives are described. The methods include applying a composition comprising a nonfunctionalized polysiloxane material to a substrate and crosslinking the nonfunctionalized polysiloxane by exposing the composition to electron beam irradiation, wherein the nonfunctionalized polysiloxane material is a nonfunctionalized polysiloxane fluid having a dynamic viscosity of no greater than 1,000,000 mPa•sec at 25 °C.