Ink composition for sensing carbon dioxide gas, carbon dioxide indicator using the same, package provided with the carbon dioxide indicator, and method for sensing pinhole using the same

Abstract

An ink composition for sensing carbon dioxide gas contains a pH indicator formed using a combination of two or more types of pH indicator components, binder, and solvent and allows easy visual observation of color changes of an indicating portion caused by the concentration of carbon dioxide gas. When the ink composition is applied to a carbon dioxide indicator and package, a pinhole and poor seal of a carbon-dioxide-ambient package are easily found.

1 . A package comprising:
 an outer package, an inner atmosphere of which contains a carbon dioxide gas; and   a carbon dioxide indicator placed in said outer package, said carbon dioxide indicator including a support and an indicating portion formed on the support using an ink composition for sensing carbon dioxide gas,   wherein the ink composition contains:
 a pH indicator changing their color as pH changes, glycerin, 
 a solvent consisting essentially of alcohol and water, 
 a binder selected from the group consisting of polyacrylic acid, polyvinyl alcohol, polyvinylbutyral, vinyl polyacetate, polyurethane, and a vinyl acetate partial saponified product, 
 an alkaline substance, and 
 a surfactant. 
   
   
   
       2 . A package according to  claim 1 , wherein said carbon dioxide indicator is placed between a container and a carbon-dioxide-impermeable outer package for packaging said container. 
   
   
       3 . A package according to  claim 1 , wherein said outer package is applied as said support, and said indicating portion is formed on at least a portion of the inner surface of said outer package. 
   
   
       4 . A package according to  claim 1 , wherein said support includes
 a carbon-dioxide-impermeable layer having a carbon dioxide permeability of not more than 50 (ml/m.sup.2.multidot.24 hr), and   a carbon-dioxide-permeable layer formed on said indicating portion, said carbon-dioxide-permeable layer having a carbon dioxide permeability of not less than 500 (ml/m.sup.2.multidot.24 hr).   
   
   
       5 . A package according to  claim 1 , further comprising at least one of an anchor coat layer formed between said support and said indicating portion, or an overcoat layer formed to cover said indicating portion. 
   
   
       6 . A package according to  claim 5 , wherein said anchor coat layer contains at least one of a urethane resin or a vinylacetal resin. 
   
   
       7 . A package according to  claim 5 , wherein said overcoat layer contains at least one of a urethane resin or a vinylacetal resin. 
   
   
       8 . A package according to  claim 1 , wherein said ink composition for sensing carbon dioxide gas further contains an alkaline substance. 
   
   
       9 . A package according to  claim 1 , wherein said solvent is at least one of water or alcohol. 
   
   
       10 . A package according to  claim 1 , wherein said binder dissolves or disperses in at least one of water or alcohol. 
   
   
       11 . A package according to  claim 1 , wherein said ink composition for sensing carbon dioxide gas further contains glycerin. 
   
   
       12 . A package according to  claim 1 , further comprising a plastic liquid medicine container containing a bicarbonate-containing liquid medicine, said plastic liquid medicine container being permeable to carbon dioxide in at least a portion thereof. 
   
   
       13 . A package according to  claim 12 , wherein the carbon dioxide concentration in said outer package is 0.5 to 10 vol %, and said bicarbonate-containing liquid medicine contains at least one of sodium salt or citrate as an additive component. 
   
   
       14 . A package according to  claim 12 , wherein the carbon dioxide concentration in said outer package is 3 to 9 vol %. 
   
   
       15 . A package according to  claim 12 , wherein said carbon dioxide indicator is placed between said liquid medicine container and a carbon-dioxide-permeable outer package packaging. 
   
   
       16 . A package according to  claim 12 , wherein said outer package is applied as said support, and said indicating portion is formed on at least a portion of the inner surface of said outer package. 
   
   
       17 . A package according to  claim 12 , wherein said pH indicator is formed using a combination of two or more pH indicator components. 
   
   
       18 . A package according to  claim 1 , wherein said pH indicator contains at least one material selected from the group consisting of Bromocresol Green, Methyl Red, Chlorophenol Red, Bromocresol Purple, Bromothymol Blue, Neutral Red, Phenol Red, Cresol Red, α-Naphtholphthalein, Curcumin, Metacresol Purple, Ethylbis (2,4 dinitro-phenyl) acetate, Thymol blue, p-Xylenol Blue, and Phenolphthalein. 
   
   
       19 . A package according to  claim 1 , further comprising a coloring agent selected from the group consisting of Food Red No. 2 (Amaranth, Food Red No. 3 (Erythrosine, Food Red No. 40 (Alura red AC, Food Red No. 102 (New Coccine, Food Red No. 104 Phloxine, Food Red No. 106 (Acid Red, a natural cochineal dye, Food Yellow No. 4 (Tartrazine), Food Yellow No. 5 (Sunset Yellow FCF, a natural safflower yellow dye, Food Blue No. 1 (Brilliant Blue FCF) and Food Blue No. 2 Indigo Carmine.