Oxygen indicator for packaging

Claim 2

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.

Claim 3

The indicator of claim 1 wherein the dye is a basic thiazine dye.

Claim 4

The indicator of claim 1 wherein the dye is a triphenylmethane dye.

Claim 5

The indicator of claim 1 wherein the dye is methylene blue.

Claim 6

The indicator of claim 1 wherein the dye is new methylene blue.

Claim 7

The indicator of claim 1 wherein the dye is thionine.

Claim 8

The indicator of claim 1 wherein the dye is methyl violet.

Claim 9

The sealed package containing the indicator of claim 2 in an atmosphere free of oxygen.

Claim 10

A sealed package containing the indicator of claim 3 in an atmosphere free of oxygen.

Claim 11

A sealed package containing the indicator of claim 4 in an atmosphere free of oxygen.

Claim 12

A sealed package containing the indicator of claim 5 in an atmopshere free of oxygen.

Claim 13

A sealed package containing the indicator of claim 6 in an atmosphere free of oxygen.

Claim 14

A sealed package containing the indicator of claim 7 in an atmosphere free of oxygen.

Claim 15

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.

Claim 16

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.

Claim 17

The package of claim 14 wherein the atmosphere in nitrogen.

Claim 18

The package of claim 14 wherein the atmosphere is carbon dioxide.

Claim 19

The package of claim 14 wherein the atmosphere is argon.

Claim 20

The package of claim 14 wherein the atmosphere is a vacuum.

Claim 21

The package of claim 14 wherein the indicator is visible through a transparent portion of the package.

Claim 22

The package of claim 14 wherein the substrate is a membrane sealing the contents of the package, with the leuco dye being imprinted on the membrane, the dye being visible through a transparent portion in the package.

Claim 23

A sealed package containing an oxygen indicator to show whether tampering has occurred, comprising: 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.

Claim 24

A sealed package containing an oxygen indicator to show whether tampering has occurred, comprising: 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.