Oxygen indicator for packaging
First Claim
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1. An oxygen indicator for use in an atmosphere free of oxygen, said indicator comprising a substrate carrying, in leuco state, a dye free of reducing agents and this reducing agent free dye being capable of irreversibly reacting with oxygen;
- said dye being characterized as being of the class which is reactive with oxygen to change from the leuco state to the colored state and which is reactive with reducing agent to change from the colored state to the leuco state.
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Abstract
A tamper-resistant package containing in an anerobic environment a leuco dye free of reducing agent which dye becomes colored upon reaction with oxygen.
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Citations
21 Claims
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1. An oxygen indicator for use in an atmosphere free of oxygen, said indicator comprising a substrate carrying, in leuco state, a dye free of reducing agents and this reducing agent free dye being capable of irreversibly reacting with oxygen;
- said dye being characterized as being of the class which is reactive with oxygen to change from the leuco state to the colored state and which is reactive with reducing agent to change from the colored state to the leuco state.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A sealed package containing an oxygen indicator in an atmosphere free of oxygen, said indicator comprising a substrate carrying, in leuco state, a dye free of reducing agent and this reducing agent free dye being capable of irreversibly reacting with oxygen;
- said dye being characterized as being of the class which is reactive with oxygen to change from the leuco state to the colored state and which is reactive with reducing agent to change from the colored state to the leuco state.
- View Dependent Claims (15, 16, 17, 18, 19, 20)
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21. A sealed package containing an oxygen indicator to show whether tampering has occurred, comprising:
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a hermetically-sealed container having a cap portion and a body portion, said cap portion possessing a window in its top, and being capable of forming a hermetic seal with said body portion when said cap and body portions are joined together; said cap and body being joined together to form said sealed container; said container having therein an atmosphere free of oxygen; a dye in leuco state, carried on a substrate; said dye being free of reducing agent and being of the class which is reactive with oxygen to change from the leuco state to the colored state and which is reactive with reducing agent to change from the colored state to the leuco state; said dye-carrying substrate being disposed and retained in said body so that it is visible through the window in said cap when cap and body are joined together and is capable of contacting surrounding air when the cap portion is removed; whereby if the integrity of the package is broken, permitting oxygen from the air to contact said dye, the dye changes to its colored form irreversibly, to provide a warning.
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Specification