US 8,927,801 B2  10  9  gen bonding, ionic, polar covalent bonding, Van der Waals  forces, dipole-dipole forces, London dispersion forces and  combinations thereof.  The first binding agent may be employed in compositions  at levels which are effective at immobilizing and stabilizing  the colorant in its first state, including from about 4% to about  90%, from about 10% to about 75%, and from about 20% to  about 65%, by weight of the composition.  The second binding agent may be any material which 10  immobilizes the colorant when the colorant is in its final color  state. There are various materials which may be suitable for  use as the second binding agent for the wetness indicating  compositions of the present invention.  (ii) Second Binding Agent  In one embodiment of the present invention the second 15  binding agents may be selected from, but are not limited to  those second binding agents disclosed in U.S. Pat. No. 6,904,  865 to Klofta.  In one optional embodiment of the present invention the  second binding agent is selected from the group consisting of  quaternary ammonium salt compounds, cationic clay, poly› acrylic acid polymers, organic acids, and combinations  thereof. Examples of suitable quaternary anmionium com› pounds include, but are not limited to, dimethyl(2-ethylhexy› lhydrogenatedtallowalkyl)  anmionium  methyl  sulfate,  cocoalky !methyl [ ethoxy lated(l 5)] anmionium  chloride,  dodecyltrimethyl ammonium chloride, hexadecyltrimethyl  ammonium methyl sulfate, octadecyltrimethyl ammonium  chloride, dicocoalkyldimethly ammonium chloride, di(hy› drogenated tallowalkyl)dimethyl ammonium chloride, and  distearyldimethyl ammonium chloride.  It  should be noted that the counter anion associated with the  quaternary compound, or any second binding agent having  one or more cationic group, is not specifically limited to  chloride. Other anions can also be employed and non-limiting  examples include methyl sulfate and nitrite. Similarly, any  suitable counter cation, such as, but not limited to, sodium,  potassium, calcium, magnesium, zinc, protons, ammonium,  substituted ammonium and the like, may be associated with a  second binding agent having one or more anionic groups.  The second binding material immobilizes the colorant  when in its final color state. How the second binding material  immobilizes the colorant when in its final color state depends  upon the chemical composition of both the second binding  material and colorant. For example, if the colorant’s final  color state is that of an anionic long chain molecule and the  second binding material is a cationic molecule, then the bond  formed may be, for example, an ionic bond, a covalent bond,  or the like. Another example, if the colorant’s final color state  is that of a cationic molecule, and the second binding material  is an anionic long chain molecule, then the bond formed may  be, for example, an ionic bond, covalent bond, or the like.  In one embodiment of the present invention the second  binding agent immobilizes the colorant when the colorant is  in its final color state by one or more selected from the group  consisting of covalent bonding, ionic bonding, Van der Waals,  and combinations thereof.  Without wishing to be bound by theory, it is believed that  when the colorant is an anion in its final color state and the  second binding agent is a cation or the colorant is a cation in  its final color state and the second binding agent is an anion,  the second binding agent forms an ionically bonded coacer› vate with the colorant. For example, when the final state  associated with a colorant’s final color state is the pH of urine,  contacting the colorant with urine will change the colorant to  its final color state, i.e., an anion, and this forms an ionic bond  with the second binding agent, which is a cation. The coac- One of the key properties of a properly functioning wetness  indicator is for it to maintain its dry state color during a variety  of storage and packaging conditions while still undergoing a  noticeable color change in a reasonable amount of time after  being contacted by urine. The colorant should also remain  stable to various chemicals and materials that might be  present in the diaper. Although acidic moieties present in the  rosins as part of the matrix can aid in preserving the  dry  state  color, additional stabilizer ingredients have been found to be  necessary with some new diaper designs where high pH com› ponents within the diaper can cause the undesirable and pre› mature color change activation of the colorant. To maintain  In one embodiment of the present invention, the stabilizer  is an acidic stabilizer. In another embodiment of the present  invention, the stabilizer is a basic stabilizer. The inclusion of  a stabilizer, while not wishing to be limited by theory, is  believed to play a role in stabilizing the colorant against  premature changes caused by exposure to humid environ› ments and/or certain components of the diaper, by maintain- ing a stable pH, such as a low pH environment with an acidic  stabilizer, around the colorant even when the system is  exposed to high humidities and/or certain components of the  diaper. This maintenance of a stable pH environment keeps  the colorant, especially when the colorant is a pH indicator, in  its initial dry color state.  The second binding agent may be employed in composi- tions at levels which are effective at immobilizing the colo› rant in its second state, including from about 0.5% to about  20%, fromabout0.5% to about 10%, and from about 0.1 %to  about 5%, by weight of the composition.  Wetness indicator compositions of the present invention  may include a stabilizer.  It  may be desirable to include a  stabilizer when the colorant is a pH indicator and when the  absorbent article could be stored under conditions of high  humidities and temperatures. The inclusion of a stabilizer  within the wetness indicator composition is also especially  important for new diaper designs where materials and/or  chemicals are present that could potentially prematurely acti› vate the color change of the colorant within the wetness  indicator composition.  Stabilizer Ingredient  In certain optional embodiments of the present invention,  use of cationic quaternary anm10nium compounds as the sec› ond binding agent may also function to darken or intensify the  color change of certain colorants, especially those belonging  to the sulfonephthalein class of pH indicators. Without wish› ing to be bound by theory, it is believed this darkening is due  to several possible factors: 1) alkaline impurities within the  quaternary anm10nium raw material, 2) absorption shifting  and absorptivity coefficient increases due to coacervate for- mation and/or 3) increased formation of the colorant in its  final color state.  ervate formation is due to the strong coulombic interaction  between the opposite charges of the colorant and the second  binding agent. The coacervate formed between the colorant  and the second binding agent neutralizes the charge in both  species and dramatically reduces both of their solubilities in  polar solvents such as water or urine while the coacervate’s  solubility in the matrix remains high due to this charge neu› tralization and the coacervate’s more lipophilic nature. Both  of these effects dramatically inhibits the leaching of the colo› rant from the matrix. The increased lipophilicity of the coac› ervate leads to increased intermolecular bonding forces  between the coacervate and components of the matrix. These  intermolecular forces may further limit the diffusion and  mobility of the colorant into an aqueous environment such as  unne. 