US 2017/0014278 Al  1  Jan. 19, 2017  ABSORBENT ARTICLES COMPRISING  WETNESS INDICATORS  CROSS REFERENCE TO RELATED  APPLICATIONS  FIELD OF THE INVENTION  BACKGROUND OF THE INVENTION  [0001]  This application is a continuation of, and claims  priority to U.S. patent application Ser. No. 14/567,021, filed  on Dec. 11, 2014, which is a continuation of U.S. patent  application Ser. No. 12/758,165, filed on Apr. 12, 2010,  which claims the benefit of U.S. Provisional Application No.  61/168,756, filed Apr. 13, 2009, the substances of which are  incorporated herein by reference.  indicator composition should be easily made, easily pro› cessed for application onto the wearable article, be safe, and  of economical cost.  [0004]  While problems realized in the past (including high  humidity and temperature environments) remain, there are  additional challenges associated with new diaper designs,  particularly including diaper designs comprising absorbent  cores that are substantially cellulose free. These core designs  comprise increased levels of absorbent polymer material,  adhesives (including, thermoplastic adhesive materials), and  surfactants. Each of these comprise chemical compositions  that can alter the pH of the wetness indicator composition  and thus cause a color change prior to a wetness event.  Particularly, alkaline surfactants containing amine, amide, or  quaternary functionalities are especially problematic for  wetness indicator compositions comprising colorants that  change color as the pH rises; but even lower pH moieties  like carboxylates can also pose challenges and prematurely  activate certain colorants within such wetness indicator  compositions.  [0002]  This invention is directed to wetness indicators  comprising wetness indicator compositions. Particularly,  wetness indication compositions having improved colorant  stability.  [0003]  Many disposable absorbent articles comprise a  wetness indicator composition. Wetness indicator composi› tions may comprise a colorant adapted to change in appear› ance, i.e., appear, disappear, change color, etc., upon contact  with liquids such as, urine, runny bowel movements, men› ses, etc., in the article. Wetness indicating compositions  described herein are of the substantially insoluble type such  that they are designed so the composition generally remains  in the same location of the article before and after being  wetted with liquid. Some wetness indicator compositions are  intentionally designed to simply disappear into the core of  the diaper after being wetted (e.g., wetted with urine).  Wetness indicator compositions of the present invention  may function to serve the following: 1) the wetness indicator  composition should effectively adhere, but not substantially  bleed through, to the substrate on which it is applied (e.g.,  the backsheet) and should possess an optimum balance of  cohesive strength and flexibility to remain intact during  storage, as well as upon and after being wetted, 2) the initial  color of the wetness indicator composition should not pre› maturely change color such that it confuses the caregiver or  wearer as to whether a wetness event has occurred, 3) the  color change of the wetness indicator composition should  occur as quickly as possible after the wetness event, 4) the  contrast in colors between the dry and wetted states of the  wetness indicator composition should be great enough to  signal the occurrence of the wetness event, 5) the color  signaling the wetness event should remain visible for a long  period of time after the wetness event and should not migrate  to other regions of the diaper such that the signal denoting  the wetness event becomes difficult or impossible to inter› pret, 6) the wetness indicators of the present invention  should adhere, but not substantially bleed through, to the  substrate that it comes in direct contact with ( e.g., the  nonwoven dusting layer) or that it is in close proximity to  ( e.g., the core cover) to provide for adequate wicking of fluid  (e.g., urine), 7) the wetness indicator composition should  remain stable (i.e., not change color prior to a wetness event)  when placed in close proximity (if not direct contact) with  higher (versus the colorant of the wetness indicator compo› sition) pH absorbent article components, and 8) the wetness  [0007]  Beyond these stability issues, the wetness indicator  composition should adhere to the substrate ( e.g., the dusting  layer) it faces that is inboard of the wetness indicator to  [0006]  In diaper designs, placing the wetness indicator  composition in close proximity to absorbent cores that are  substantially cellulose free or comprising high levels of  surfactants, there is a desire to optimize the acid content in  relation to other materials present in the wetness indicator  composition to aid in preventing its premature color change.  This is especially true when the diaper design utilizes lower  basis weight and more breathable substrates (e.g., back› sheets, dusting layers, and core covers) because these sub› strates allow pH altering chemicals to come in closer prox› imity with the wetness indicator composition. But, while the  acid content is optimized for stability, one also needs to  optimize the wetness indicator composition for proper func› tioning of the other properties ( e.g., kinetics, dye retention,  stability, adhesion, etc.).  If  too much acid or too strong of an  acid mixture is incorporated, the pH can remain suppressed  even after the wetness event such that the yellow color of the  bromocresol green, for instance, persists and no blue color  (signaling a wetness event) results even when a wetness  event has occurred.  If  too little acid or too weak of an acid  mixture is incorporated, the wetness indicator composition  can prematurely change color. Thus, the acid content should  be optimized so the wetness indicator composition remains  stable under various storage scenarios, as well as within new  challenging absorbent article designs.  [0005]  The color changing active used in many wetness  indicator compositions are pH indicators like bromocresol  green which changes color from yellow to blue in the pH  range of 3.8 to 5.4. To maintain the yellow color of the  bromocresol green in the dry state, the wetness indicator  composition should be acidic enough to keep it in its yellow  state. For a wetness indicator composition containing the  bromocresol green pH indicator, it remains yellow up to the  point urine contacts it and thereafter turns blue due to the pH  increase. In diapers incorporating a wetness indicator com› position comprising a colorant that changes color as its pH  increases, it is common practice for one to incorporate acids  (as well as other chemical components discussed in more  detail below) within the wetness indicator composition to  maintain the yellow color state of pH indicators, like bro› mocresol green, prior to a wetness event. 