Vacuum Curing Composition with Gas-Generated UV Radiation
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Solution Overview
Problem
Existing methods for forming thin, solid polymeric films in vacuum chambers face challenges such as unwanted solid formation on equipment and low rates of electron beam-induced cationic polymerization, which hinder high-speed coating applications and uniformity on non-oxidized metal surfaces.
Innovation Solution
A radiation curable composition comprising a polymerizable component and a cationic photoinitiator is applied in liquid form under vacuum, with a gas introduced to emit UV and plasma radiation upon electron beam exposure, facilitating polymerization or crosslinking without transitioning into a gas phase, and enhancing the curing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If liquid monomer is vaporized and deposited in vacuum chamber, then thin solid polymeric films can be formed, but unwanted solid forms on equipment surfaces making cleanup difficult
Solution Approach 1:
The invention changes the physical state parameter of the composition by formulating it to remain liquid under vacuum conditions rather than vaporizing. This is achieved by selecting components with appropriate vapor pressures and using reactive diluents that maintain liquid state, thereby preventing deposition on equipment surfaces while still enabling film formation on substrates.
Solution Approach 2:
The invention uses vacuum as an inert environment to prevent oxidation of metal substrates while maintaining the composition in liquid state. The vacuum chamber provides a controlled atmosphere that allows liquid deposition without solvent evaporation, and the composition is formulated to be stable and non-vaporizing in this inert environment.
2Reliability
If electron beam radiation is used to cure composition in vacuum, then complete curing can be achieved, but cationic polymerization rate is too slow for high-speed applications
Solution Approach 1:
The invention introduces a photoinitiator system as an intermediary that converts electron beam energy into UV radiation, which then initiates cationic polymerization. This two-stage energy conversion process (electron beam → UV → chemical reaction) provides faster polymerization rates compared to direct electron beam curing, enabling high-speed coating applications while maintaining complete curing.
Solution Approach 2:
The invention replaces direct electron beam-induced polymerization with a photopolymerization mechanism initiated by UV radiation. This substitution changes the fundamental curing mechanism from direct radiative polymerization to photochemical polymerization, which proceeds at faster rates and is better suited for high-productivity applications.
3Manufacturing precision
If composition is applied in liquid form under vacuum, then uniform coating on non-oxidized metal surfaces is achieved, but composition must not transition to gas phase
Solution Approach 1:
The invention modifies the composition's physical parameters by formulating it with components having low vapor pressures and using reactive diluents that maintain liquid state under vacuum. The composition is designed with specific molecular weights and intermolecular forces that prevent vaporization while maintaining fluidity for uniform coating application.
Solution Approach 2:
The invention uses composite formulation combining polymerizable monomers, oligomers, and reactive diluents in specific ratios. This composite approach allows the composition to exhibit both low vapor pressure (for vacuum stability) and appropriate viscosity (for uniform coating), achieving both phase stability and coating uniformity simultaneously.
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 allows for efficient, uniform curing of the composition on substrates with high adhesion and minimal equipment contamination, achieving rapid and complete polymerization or crosslinking, even on non-oxidized metal surfaces, while maintaining the composition in a liquid state under vacuum conditions.
Implementation Method 1
electron beam radiation which generates ultraviolet radiation and plasma radiation upon exposure thereto
Implementation Method 2
plasma radiation, or combinations of ultraviolet radiation and plasma radiation upon exposure to electron beam radiation
Implementation Method 3
ultraviolet radiation, plasma radiation, or combinations of ultraviolet radiation and plasma radiation upon exposure to electron beam radiation
Implementation Method 4
a cationic photoinitiator which generates an acid upon exposure to ultraviolet radiation, plasma radiation, electron beam radiation or combinations thereof, thus causing polymerizing or crosslinking
Data Source
AI summary
A process for producing polymeric films by applying a liquid composition onto a surface of a substrate under vacuum conditions in a vacuum chamber. The composition has a first component which is polymerizable or crosslinkable in the presence of a sufficient amount of an acid; and a cationic photoinitiator which generates an acid upon exposure to ultraviolet radiation, electron beam radiation or both to cause polymerizing or crosslinking of the first component. A gas which emits ultraviolet radiation upon exposure to electron beam radiation is introduced into the vacuum chamber. The composition and the gas are exposed to electron beam radiation to cause the cationic photoinitiator to generate an amount of an acid to cause polymerizing or crosslinking of the first component. The composition is exposed to both electron beam radiation and gas-generated ultraviolet radiation and cured.