Cork Stopper Polymeric Coating Curing Process
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Solution Overview
Problem
Cork stoppers contaminate white alcoholic beverages with phenolic and polyphenolic compounds, causing undesirable yellowish coloration due to the inefficacy of existing methods in preventing the migration of these compounds, which limits their market entry for high-alcohol content beverages.
Innovation Solution
A process involving a polymeric coating made of cross-linked silicone (PDMS) is applied to cork stoppers, ensuring complete surface and pore coverage, with a gradual curing process to prevent pore formation in the coating, thereby creating a high-impermeability barrier against these compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional coating methods (polyethylene, EVA, PVDC, PVC, polyurethane) are applied to cork stoppers, then coating adhesion is improved through heating or UV pre-treatment, but the migration of phenolic and polyphenolic compounds into white alcoholic beverages is not sufficiently delayed
Solution Approach 1:
The patent applies a gradual curing process with controlled temperature variation rates (3-6 °C/min) to transform the coating from a non-cured state to a cross-linked polymeric structure. This parameter change in temperature control during curing creates a dense, pore-free coating that effectively blocks phenolic and polyphenolic compound migration while maintaining adhesion to the cork stopper
Solution Approach 2:
The patent uses cross-linked silicone (PDMS) as a polymeric coating material that combines the adhesion properties of conventional coatings with superior barrier performance. The cross-linked polymeric structure creates a composite barrier system that simultaneously achieves reliable adhesion to cork and effective prevention of colored compound migration into beverages
2Productivity
If rapid curing is applied to the polymeric coating, then production time is reduced, but pore formation occurs in the coating reducing its barrier effectiveness
Solution Approach 1:
The patent implements a preliminary gradual curing stage before final curing, where temperature is increased at a controlled rate (3-6 °C/min) to prepare the coating structure. This preliminary action prevents pore formation by allowing gradual outgassing and uniform cross-linking initiation, ensuring the coating maintains its integrity and barrier properties throughout the curing process
Solution Approach 2:
The curing process is divided into distinct periodic stages: a gradual heating phase with controlled temperature variation rates, followed by a final curing phase at higher temperatures. This periodic action allows the coating to develop its barrier properties systematically, preventing pore formation while maintaining production efficiency through optimized time-temperature profiles
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 coating significantly reduces the migration of phenolic and polyphenolic compounds into beverages, allowing cork stoppers to be used in white alcoholic beverages for extended periods without causing coloration, surpassing the limitations of prior art methods.
Implementation Method 1
A coating with pores has a lower barrier effect than a free-pore coating. The coating process for cork stoppers of the invention provides an impermeability of stoppers to those undesirable compounds which was never achieved with the related prior art processes and coatings.
Implementation Method 2
gradual curing of the polymeric coating by applying a temperature variation rate in the range of about 3 °C/min to about 6 °C/min, in order to gradually raise the temperature from about 40 °C to about 110 °C
Implementation Method 3
depositing a polymeric film on cork stoppers providing a non-cured polymeric coating on said stoppers
Data Source
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AI summary
The present invention discloses a process for applying a polymeric coating that provides an efficient barrier effect to the migration of coloured compounds, namely polyphenols, from the cork stopper into a white alcoholic beverage. For this effect the process of the invention comprises the steps of: 1) depositing a polymeric film on cork stoppers to provide a non-cured polymeric coating on the stoppers; 2) gradual curing of the polymeric coating by applying a temperature variation rate in the range of about 3 °C/min to about 6 °C/min, in order to gradually raise the temperature from about 40 °C to about 110 °C; and 3) final curing of the polymeric coating at constant temperature in the range of about 70 °C to 120 °C for at least 5 minutes. The efficacy of this coating will make possible the implementation at industrial level of cork stoppers in the market of white alcoholic beverages.