Electron Beam Cured Silicone Adhesives
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Solution Overview
Problem
Current silicone pressure sensitive adhesives (PSAs) face challenges in low VOC delivery and require catalysts for curing, limiting their versatility and performance, especially in hot-melt coating processes where premature curing is undesirable.
Innovation Solution
The development of a crosslinked silicone-based material cured by electron beam irradiation, which is non-functionalized and free of catalysts and initiators, using polysiloxane materials with an aromatic siloxane backbone and an MQ resin tackifier, allowing for a broader range of chemistries and improved performance without the need for solvents or reactive groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermal curing processes with catalysts are used, then adhesion performance is achieved, but the system requires catalysts and reactive functional groups which limits versatility and may cause premature curing
Solution Approach 1:
The patent replaces chemical curing mechanisms (catalysts and reactive functional groups) with physical electron beam irradiation. The electron beam provides energy to initiate crosslinking without requiring chemical catalysts, thus substituting a chemical system with a physical radiation system. This enables curing of non-functionalized silicones and expands chemistry versatility.
Solution Approach 2:
The patent changes the curing mechanism from thermal/chemical parameters to radiation energy parameters. By using electron beam irradiation with controlled energy levels, the system achieves curing without catalysts and can process a broader range of silicone chemistries including non-functionalized materials, thus improving adaptability while maintaining adhesion performance.
2Reliability
If high molecular weight starting materials are used, then adhesion performance is improved, but the materials require solvent dilution which increases VOC content
Solution Approach 1:
The patent applies electron beam irradiation to induce crosslinking and gelation during or after the coating process. This preliminary crosslinking action increases the effective molecular weight and network structure of the adhesive, improving adhesion performance without requiring high molecular weight starting materials that would need solvent dilution, thus reducing VOC content.
Solution Approach 2:
The patent creates a composite structure through crosslinking of silicone polymers with various functional groups (vinyl, hydrogen, epoxy, acrylate) to form a networked adhesive system. This composite crosslinked structure achieves the mechanical properties of high molecular weight materials while using lower molecular weight precursors that can be applied with reduced solvent content.
3Reliability
If crosslinking is added to improve adhesion, then adhesion performance is enhanced, but conventional crosslinking requires catalysts and reactive functional groups
Solution Approach 1:
The patent replaces complex chemical crosslinking systems (multiple catalysts and reactive functional groups) with a simpler physical crosslinking method using electron beam irradiation. The electron beam directly provides the energy needed to break bonds and form radicals that initiate crosslinking, eliminating the need for complex catalyst systems and reducing overall system complexity.
Solution Approach 2:
The patent extracts and removes the catalyst and initiator components from the crosslinking system. By using electron beam irradiation as the sole crosslinking mechanism, the system eliminates the need for platinum catalysts, peroxides, tin catalysts, and other chemical initiators, simplifying the formulation and reducing the number of components required.
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 method enables the production of silicone PSAs with enhanced adhesion and stability, achieving comparable performance to traditionally cured adhesives without the use of catalysts, and allows for the creation of silicone foams with controlled cell structures and uniform distribution, offering improved control over foam properties.
Implementation Method 1
cured by exposure to electron beam irradiation
Data Source
Figure 1~2
AI summary
Methods of preparing silicone materials using electron beam curing are described. The materials are hot melt processed and cured in the absence of an effective amount of catalysts and initiators. Both functional and nonfunctionalized silicone materials may be used. Exemplary cured materials include silicone pressure sensitive adhesives, silicone foams, and non-tacky silicone films.