side) wetted and thus provides the full signal intended. This  can be accomplished by providing a wetness indicator  composition that has an optimized "open time" such it is  tacky enough, during its incorporation into an absorbent  article, for a long enough time to adhere to the substrate, but  not so long that it bleeds through the substrate.  Overall, there remains a need for a wetness indicator  composition that is stable in the presence of challenging  diaper designs, particularly those designs comprising: absor› bent cores that are substantially cellulose free and compris- ing high levels of adhesive (including, thermoplastic adhe› sive material) and absorbent polymer material, lower basis  weight dusting layers and backsheets, and dusting layers  and/or core covers coated with surfactants. Particularly,  there is a need for more acidic wetness indicator composi- tions that comprise less phosphorus and/or nitrogen (which  correlates to greater colorant stability while still providing  acceptable color changing kinetics and retention). Addition› ally, there is a need for a wetness indicator composition that  has an optimized "open time" for use in absorbent articles  comprising lower basis weight and breathable films and  nonwovens.  An absorbent article of the present invention may com› prise a backsheet, a wetness indicator composition, and an  absorbent core. The wetness indicator composition may  comprise a stabilizer, a colorant, and a matrix. The absorbent  core may comprise a nonwoven layer and an absorbent  polymer material, and optionally, a thermoplastic adhesive  material. The wetness indicator composition may be in  direct contact with an inner surface of the backsheet and an  outer surface of the nonwoven layer. And, the absorbent  polymer material, and optionally, the thermoplastic adhesive  material, may be in direct contact with an inner surface of  the nonwoven. Further, the absorbent core may be substan› tially cellulose free and may be oriented in at least one row.  FIG.  1  is a partial longitudinal cross sectional view of an  absorbent core ( comprising a nonwoven layer and a complex  of absorbent polymer material and thermoplastic adhesive  material) in accordance with an embodiment of the present  invention.  It should be understood that every limit given throughout  this specification will include every lower, or higher limit, as  the case may be, as if such lower or higher limit was  expressly written herein. Every range given throughout this  specification will include every narrower range that falls  within such broader range, as if such narrower ranges were  all expressly written herein.  All percentages, ratios and proportions are by weight, and  all temperatures are in degrees Celsius  (°  C.), unless other› wise specified. All measurements are in SI units unless  otherwise specified.  "Absorbent article" refers to devices that absorb and  contain body exudates, and, more specifically, refers to  devices that are placed against or in proximity to the body  of the wearer to absorb and contain the various exudates  discharged from the body. Absorbent articles may include  diapers, training pants, adult incontinence undergarments,  "Fiber" and "filament" are used interchangeably.  A "nonwoven" is a manufactured sheet, web, or batt of  directionally or randomly orientated fibers, bonded by fric- tion, and/or cohesion and/or adhesion, excluding paper and  products which are woven, knitted, tufted, stitch-bonded  incorporating binding yarns or filaments, or felted by wet- "Diaper" refers to an absorbent article generally worn by  infants and incontinent persons about the lower torso so as  to encircle the waist and legs of the wearer and that is  specifically adapted to receive and contain urinary and fecal  waste. As used herein, term "diaper" also includes "pants"  which is defined below.  "Consisting essentially of’ is used herein to limit the  scope of subject matter, such as that in a claim, to the  specified materials or steps and those that do not materially  affect the basic and novel characteristics of the subject  matter.  "Comprise," "comprising," and "comprises" are open  ended terms, each specifies the presence of what follows,  e.g., a component, but does not preclude the presence of  other features, e.g., elements, steps, components known in  the art, or disclosed herein.  "Airfelt" is used herein to refer to comminuted wood  pulp, which is a form of cellulosic fiber.  "Absorbent polymer material," "absorbent gelling mate› rial," "AGM," "superabsorbent," and "superabsorbent mate› rial" are used herein interchangeably and refer to cross  linked polymeric materials that can absorb at least 5 times  their weight of an aqueous 0.9% saline solution as measured  using the Centrifuge Retention Capacity test (Edana 441.2- 01).  feminine hygiene products, breast pads, care mats, bibs,  wound dressing products, and the like. As used herein, the  term "body fluids" or "body exudates" includes, but is not  limited to, urine, blood, vaginal discharges, breast milk,  sweat and fecal matter.  "Absorbent core" means a structure typically disposed  between a top sheet and backsheet of an absorbent article for  absorbing and containing liquid received by the absorbent  article and may comprise one or more substrates, absorbent  polymer material disposed on the one or more substrates,  and a thermoplastic composition on the absorbent particulate  polymer material and at least a portion of the one or more  substrates for immobilizing the absorbent particulate poly› mer material on the one or more substrates. In a multilayer  absorbent core, the absorbent core may also include a cover  layer. The one or more substrates and the cover layer may  comprise a nonwoven. Further, the absorbent core is sub› stantially cellulose free. The absorbent core does not include  an acquisition system, a topsheet, or a backsheet of the  absorbent article. In a certain embodiment, the absorbent  core would consist essentially of the one or more substrates,  the absorbent polymer material, the thermoplastic compo› sition, and optionally the cover layer. Absorbent cores that  may be used in the present invention are disclosed in US  Pub. Nos. 2004/0162536 to Becker filed on Feb. 11, 2004;  2007/0167928 to Becker filed on Mar. 13, 2007; 2007/  0179464 to Becker filed on Mar. 13, 2007; 2007/0156108 to  Becker filed on Mar. 13, 2007; and 2004/0167486 to Busam  filed on Feb. 11, 2004; U.S. Ser. No. 60/936,102 to Hundorf  filed on Jun. 18, 2007; 60/936,109 to Hundorf filed on Jun.  18, 2007; 60/936,149 to Hundorf filed on Jun. 18, 2007;  60/936,085 to Ashton filed on Jun. 18, 2007; 60/936,084 to  Ashton filed on Jun. 18, 2007; 60/936, 150 to Ashton filed on  Jun. 18, 2007; 60/936,146 to Asthon filed on Jun. 18, 2007;  60/936,037 to Ashton filed on Jun. 18, 2007; and 61/091,799  to Hundorf filed on Aug. 26, 2008.  SUMMARY OF THE INVENTION  BRIEF DESCRIPTION OF THE DRAWINGS  DETAILED DESCRIPTION OF THE  INVENTION  US 9,468,565 B2  4  3 