Wetness indicator free from halogen-containing species

Abstract

To provide: a new wetness indicator composition that is thermally and environmentally stable, that has intense color change and good wash-out resistance, that can withstand multiple insults during use, that is easy to manufacture and apply, and that is free from halogen-containing species; and a hygiene article comprising a hot melt wetness indicator.SOLUTION: A hot melt wetness indicator composition comprises: 1-80 wt.% of a base polymer; 15-75 wt.% of a tackifier; a pH adjuster in an amount sufficient to cause the pH of the composition to be less than 6; and 0.01-5 wt.% of a pH indicating agent consisting of nitrazine yellow.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a hot melt wetness indicator adhesive composition that can be used in disposable nonwoven absorbent articles such as diapers. The indicator adhesive indicates wetness when bodily fluids are expelled from the wearer by changing from a first color to a second color (or from colorless to colored) without the use of halogen-containing compounds. [Background technology]

[0002] Disposable nonwoven absorbent products have gained widespread acceptance for infant, child, and adult incontinent care applications. Typical disposable nonwoven absorbent articles include diapers, training pants, adult incontinent pads and briefs, feminine sanitary napkins or pads, and tampons. Disposable nonwoven absorbent articles such as those described above function to receive and contain urine and other bodily fluids secreted by the wearer. These items are worn against or adjacent to the wearer's skin.

[0003] A typical disposable nonwoven absorbent article consists of a fluid-impermeable film backsheet, a porous, fluid-permeable nonwoven topsheet, and an absorbent core sandwiched between the topsheet and backsheet. These articles are usually bonded using hot-melt adhesives and do not require an indicator strip to further bond the film and nonwoven components together. In addition to this basic structure, these absorbent articles usually have many other features to either improve fluid containment or enhance the wearer's comfort level. For example, infant diapers include elastic leg cuffs attached to the topsheet for enhanced liquid containment.

[0004] Because disposable nonwoven absorbent articles are widely used for their body fluid containment function, it is desirable to know whether the article is wet and therefore needs to be changed. Monitoring wetness by internal visual inspection can be time-consuming and uncomfortable. Therefore, incorporating an externally visible wetness indicator into disposable nonwoven absorbent articles such as diapers would be highly valuable.

[0005] An approach using wetness indicator adhesives or coated stripes of wetness indicators to indicate wetness as a color change is described in U.S. Pat. No. 4,231,370 to Mroz et al. This patent discloses an improved absorbent product having a wetness indicator disposed between a translucent cover member and an absorbent member. According to the disclosure, the wetness indicator is applied in the form of a stripe to a portion of the inward-facing surface of the disposable diaper backsheet. Such wetness indicators contain a pH-changing / color-changing colorant dispersed in an aqueous adhesive latex of styrene / 2-ethylhexyl acrylate copolymer, ethylene / vinyl acetate copolymer, or polyvinyl acetate. The indicator adheres to the backsheet and dries to form a yellow, flexible coating. Upon challenge with bodily secretions such as urine, the indicator changes from yellow to blue, signaling the presence of moisture. To achieve the appropriate pH, sufficient acid buffering means, such as phosphoric acid, must be added to the latex. Phosphoric acid is a harsh acid, which may raise safety concerns. Another disadvantage of this patent is that a means for water or solvent removal must be provided during manufacture.

[0006] Colon et al., U.S. Patent Nos. 4,681,576, 4,743,238, and 4,895,567, disclose hot-melt wetness indicator adhesives that change color upon attack by urine or water. These adhesives are based on water-soluble polyvinylpyrrolidone polymers, or water-soluble vinylpyrrolidone-vinyl acetate copolymers, or ethylene-acrylic acid copolymers, in combination with fatty acids and wetness-indicating dyes. The compositions can include various other ingredients, such as water-soluble waxes, glycerol esters, ethylene-vinyl acetate copolymers, and hydrogenated oils.

[0007] Zimmel et al., U.S. Patent No. 5,035,691, discloses a hot-melt wetness indicator composition based on an adduct prepared by reacting an ethylene-acrylic acid copolymer with polyethylene oxide under monobutyltin(IV) oxide catalysis. The composition contains 0.03% to 0.5% by weight of an acid-base indicator as the active ingredient for indicating the presence of moisture.

[0008] Raykovitz et al., U.S. Pat. No. 5,342,861, discloses compositions similar to those of Zimmel et al. in that the compositions include a wetness indicator such as a pH indicator, a graft copolymer prepared by reacting a vinyl polymer with a low molecular weight polyethylene oxide, and a compatible tackifier.

[0009] Nitrazine yellow has been used as a wetness indicator to indicate that a diaper has been attacked by urine. For example, Habji et al., International Publication No. 2016 / 120876, describes a design for a wetness indicator in a diaper in which the wetness indicator protrudes in the form of an extending tab, allowing a color change to be observed without removing the garment. Nitrazine yellow is dissolved in a solvent such as methanol and then dried onto a gauze or substrate that serves as the tab.

[0010] Klofta et al., U.S. Patent Application Publication No. 2016 / 0038628, discloses a wetness indicator that may be in the form of a hot melt adhesive. Klofta et al. require not only a pH indicator (such as nitrazine, among many possibilities), but also the use of a permanent dye for the wetness indicator to function properly. Furthermore, Klofta et al. do not contemplate the use of polyethylene glycol as either the sole base polymer or one of the base polymers.

[0011] Song et al., U.S. Patent No. 9,889,222, discloses a coating composition sensitive to aqueous media that is applied to an absorbent article adjacent to the longitudinal side peripheral edge. The coating composition includes a betaine ester or betaine ester derivative having a functional active group derived from a hydroxyl-containing fragrance, and a color-changing visual indicator chemistry selected from at least one of the group consisting of pH indicator dyes and pH adjusters, thermochromic dyes, and polarity-sensitive dyes.

[0012] Unlike the prior art, the invention described herein requires advanced knowledge of wetness indicator technology and incorporates an unconventional pH indicator to enable a wetness indicator that does not contain potentially harmful halogen species. Finally, the above prior art merely describes the use of nitrazine as a pH indicator, among many other pH indicators that would not likely work in the present application.

[0013] Klofta et al., U.S. Patent No. 9,320,824, discloses a liquid-activated formulation in a solvent-based bonding matrix for use as a wetness / fluid indicator in absorbent articles, the formulation including a liquid-activated colorant, a hydrochromic ionic compound, an opacifier, and a solvent-based bonding matrix. Summary of the Invention [Problem to be solved by the invention]

[0014] The prior art compositions described herein above suffer from several drawbacks. For example, the hot melt wetness indicator composition disclosed in Colon et al. exhibits insufficient thermal stability. Therefore, when heated at the high temperatures of 250-300°F typically encountered during hot melt applications, the adhesive can undergo severe degradation, as evidenced by char, skin formation, and darkening. Most of the components in Colon's composition are incompatible with each other, and therefore, phase separation can occur in the composition during application under typical hot melt adhesive coating conditions. Other drawbacks include poor environmental stability and poor bleed-through or wash-off resistance. In some cases, coated indicators tend to slowly and prematurely change color from yellow to green and ultimately to blue due to exposure to atmospheric moisture during storage. This aspect is particularly important because finished nonwoven absorbent products can be stored in relatively hot and humid environments for several months before reaching consumers. If premature color change occurs during storage, the product becomes unusable. An additional drawback is the insufficient intensity of the indicator's color change upon attack, resulting in the color change being barely visible through a translucent substrate. On the other hand, the compositions taught by Zimmel et al. and Raykovitz require harsh conditions to carry out the chemical grafting of a low-molecular-weight hydrophilic PEG to another relatively high-molecular-weight hydrophobic polymer. Their grafting reaction requires either an organotin catalyst (Zimmel) or a peroxide initiator (Raykovitz). Issues can arise from concerns about product safety due to residual organotin compounds and peroxides. Because hydrophilic PEG is typically incompatible with the vinyl polymers used to prepare the graft copolymer, unreacted reactants can cause compatibility issues for the final wetness indicator composition.

[0015] Due to the lack of prior art products and market awareness for avoiding all halogens in hygiene articles, there is a need for new wetness indicators that are compatible, i.e., thermally and environmentally stable, have strong color change and good wash resistance, can withstand multiple attacks between uses, are easy to manufacture and apply, and are free of halogen-containing species. Furthermore, it is particularly preferred to select pH indicators and formulations such that the color of the wetness indicator undergoes a noticeable color change upon attack, such as from yellow to blue, or more preferably from yellow to purple. [Means for solving the problem]

[0016] The present invention relates to wetness indicator compositions (also called hot melt wetness indicators or hot melt wetness indicator (or indicating) adhesive compositions) comprising adhesive base compositions incorporating a halogen-free pH wetness indicator consisting of nitrazine yellow. In one embodiment, the adhesive base composition may be composed of water-soluble or at least partially water-soluble components, and in another embodiment, the adhesive base composition may be composed of water-sensitive components such as, for example, one or more water-insoluble polymers and surfactants.

[0017] Preferably, the adhesive is a hot melt adhesive. Hot melt adhesives are preferred over other types of adhesives for a number of reasons. Unlike water-based or solvent-based adhesives, there is no liquid carrier that needs to be evaporated. Hot melts are applied in a molten state and solidify upon cooling. Therefore, they can be applied at faster line speeds because no drying is required. Hot melts also tend to stay in place better because they stop flowing as soon as they cool. This is important when attempting to extrude or print patterns of adhesive.

[0018] In one embodiment, the wetness indicator is based on an at least partially water-soluble hot melt adhesive base comprising a polymer, which may be a homopolymer, copolymer, terpolymer, interpolymer, or blend thereof, together with a tackifying resin, a stabilizer, and a halogen-free pH indicator, i.e., nitrazine yellow, that changes color (or changes from pale or colorless to colored) in response to a change in pH upon contact with a liquid such as urine. The composition of the present invention overcomes the shortcomings of prior art wetness indicators. One embodiment of the present invention is to provide a wetness indicator with excellent thermal and environmental stability, improved fixation, a clear color change, easy manufacturing, and easy application.

[0019] The hot melt wetness indicator composition of the present invention can be applied using a variety of conventional coating techniques known in the art. It is particularly suitable for slot coating, multi-bead, spiral spray, and various variations of melt-blown coating. The hot melt wetness indicator can be applied in a manner that creates a pattern, letter, or picture.

[0020] A preferred wetness indicating adhesive composition of the present invention comprises the following components: (a) a base polymer in an amount of about 1% to about 80% by weight, preferably about 1% to about 45% by weight, and most preferably about 1% to 35% by weight; (b) a tackifier in an amount of about 15% to about 75% by weight, preferably about 20% to about 70% by weight, preferably about 20% to 50% by weight; (c) a pH adjuster in an amount sufficient to adjust the pH of the composition to less than 6, preferably between 4 and 6, more preferably between 5 and 6, and most preferably between 5.5 and 6; and (d) a pH indicator consisting of about 0.1% by weight to about 5% by weight of nitrazine yellow A hot melt adhesive composition comprising a mixture of

[0021] As used herein, when a single component is identified (e.g., a base polymer), the composition can include either that component alone or a mixture of such components. Optional additional components include the following: (a) a surfactant or combination of surfactants in an amount of about 1% to 30% by weight, preferably about 4% to 15% by weight; (b) a plasticizer in an amount of about 1% to 15% by weight, preferably in an amount of about 1% to 10% by weight, and most preferably in an amount of about 1% to 7% by weight; (c) 0.1% to 5% by weight of one or more stabilizers or antioxidants Includes.

[0022] The adhesive may contain other conventional ingredients such as fillers or waxes. In an embodiment of the present invention, the pH adjuster is present in an amount of about 5% to about 55% by weight, preferably about 10% to 50% by weight, and most preferably about 19% to 43% by weight.

[0023] As a hot melt adhesive, the composition does not require evaporation of water or solvent formulations upon application to the article. In one embodiment of the present invention, the hot melt wetness indicator is not formed on a separate tab that extends beyond the diaper structure. Additionally, formulations of the present invention that use nitrazine yellow as an indicator do not require the use of either permanent dyes or fluorescent agents, or both, to function properly. According to another embodiment, the hot melt wetness indicator composition is wax-free, more preferably polyethylene glycol wax-free, and / or contains polyethylene glycol as either the sole base polymer or one of the base polymers. According to another embodiment of the present invention, the hot melt wetness indicator composition is free of compounds that release functional groups with fragrances upon challenge with urine. More particularly, the hot melt wetness indicator composition of the present invention is free of betaine esters or betaine ester derivatives. According to yet another embodiment, the hot melt wetness indicator composition is free of reactive ionic compounds, such as ionizable salts. Finally, the hot melt wetness indicator does not need to be formed within or as part of a paper strip or dissolved onto a sensor.

[0024] According to one embodiment of the present invention, the hot melt wetness indicator composition consists essentially of, or consists of, a base polymer, a tackifier, a pH adjuster, a pH indicator, and optionally at least one of an antioxidant or a plasticizer. According to another embodiment of the present invention, the hot melt wetness indicator composition consists essentially of, or consists of, a base polymer, a tackifier, a pH adjuster, a pH indicator, and an antioxidant, and optionally at least one of a wax, a filler, a stabilizer, a surfactant, and a plasticizer.

[0025] In accordance with another embodiment of the present invention, the hot melt wetness indicator composition comprises from about 1% to about 80% by weight of a base polymer; from about 15% to about 75% by weight of a tackifier; a pH adjuster in an amount sufficient to bring the pH of the composition to less than 6, preferably between 4 and 6, more preferably between 5 and 6, and most preferably between 5.5 and 6; and from about 0.01% to about 5% by weight of a pH indicator comprising nitrazine yellow.

[0026] According to another embodiment of the present invention, a hygiene article comprises a fluid-impermeable backsheet having an inner surface, a nonwoven topsheet, and an absorbent core disposed between the backsheet and the topsheet; and a hot-melt wetness indicator bonded to the inner surface of the backsheet and in contact with the absorbent core, such that upon attack of the absorbent core by urine, the urine contacts the hot-melt wetness indicator, the hot-melt wetness indicator composition comprising from about 1% to about 80% by weight of a base polymer; from about 15% to about 75% by weight of a tackifier; a pH adjuster in an amount sufficient to bring the pH of the composition to less than 6, preferably 4 to 6, more preferably 5 to 6, and most preferably 5.5 to 5; and from about 0.01% to about 5% by weight of a pH indicator comprising nitrazine yellow.

[0027] Other features and advantages of the present invention may become readily apparent to those of ordinary skill in the art upon review of the following drawings and description thereof. [Brief explanation of the drawings]

[0028] [Figures 1a-1d] Figures 1(a)-1(d) show four wetness indicators of the present invention before and after challenge with saline solution. DETAILED DESCRIPTION OF THE INVENTION

[0029] According to the present invention, a hot melt wetness indicator is formulated by combining about 1% to 80% by weight of a base polymer component; about 15% to 75% by weight of a compatible tackifier; a pH adjuster in an amount sufficient to bring the pH of the composition to less than 6, preferably 4 to 6, more preferably 5 to 6, and most preferably 5.5 to 6; and about 0.01% to about 5% by weight of a pH indicator comprising nitrazine yellow. Other optional ingredients can be added to modify or enhance the physical and performance characteristics of the composition. Such optional ingredients include surfactants, plasticizers, stabilizers or antioxidants, fillers, and waxes.

[0030] Any of a variety of available thermoplastic materials can be used as the base polymer component in the compositions of the present invention, either alone or as a blend. For adhesive compositions, the polymer may be a homopolymer, copolymer, terpolymer, interpolymer, or blend thereof, and may be present in an amount of about 1% to about 80% by weight, preferably about 1% to about 45% by weight, and preferably about 1% to 40% by weight. Examples of such thermoplastic materials include ethylene-based polymers, including polyesters such as ethylene / vinyl acetate (EVA), ethylene acrylate, ethylene methacrylate, ethylene methyl acrylate, ethylene methyl methacrylate, high- and low-density polyethylene, polyethylene blends, and chemically modified polyethylenes, copolymers of ethylene with 1 to 6 mono- or di-unsaturated monomers, ethylene / styrene interpolymer (ESI), and sulfonated polyesters; amorphous polyalphaolefins (APAOs), including atactic polypropylene; metallocene-catalyzed polyalphaolefins; SIS (styrene-isoprene-styrene) block copolymers; SBS (styrene-butadiene-styrene) block copolymers; and styrene-butadiene-styrene (SBS) block copolymers. These include block copolymers; SEBS (styrene-ethylene-butylene-styrene) block copolymers; SEEPS (styrene-ethylene / ethylene propylene styrene) block copolymers; SBR (styrene-butadiene-rubber); acrylic polymers and copolymers; and styrene-acrylic polymers and copolymers; polybutene-1 homopolymers and copolymers, commonly referred to as polybutylene; linear ABA block copolymers; linear A-(BA)nB multiblock copolymers; and radial or teleblock copolymers of the formula (AB)nY, where A comprises polystyrene blocks, B comprises essentially rubber-like polybutadiene or polyisoprene blocks, Y comprises polyhydric compounds, and n is an integer of at least 3. The midblocks can be post-treated to improve their thermal stability by hydrogenation or other post-treatment to remove residual unsaturation. The size and amount of the A or end blocks in the ABA block copolymer structure can range from 14% to 51% by weight of the polymer.

[0031] In addition, water-soluble polymers may be utilized as thermoplastic materials. Common water-soluble polymers include polyesters, such as sulfonated polyesters, polyvinyl methyl ether, polyalkyleneimine polymers and copolymers, polyvinyl alcohol, polylactic acid polymers, polyethylene glycol polymers, polyacrylic acid and its salts, ethylene / acrylic acid and its salts, polyvinylpyrrolidone, and polyvinylpyrrolidone / vinyl acetate. Other water-soluble polymers may be used depending on the desired end use and polymer properties; therefore, the above list should not be considered comprehensive or limit the scope of the terms "thermoplastic material" or "thermoplastic polymer" as used herein.

[0032] In one embodiment, the base polymer comprises, consists essentially of, or consists of polyethylene glycol. In another embodiment, the base polymer comprises, consists essentially of, or consists of polyethylene glycol, preferably in an amount of about 10% to about 55% by weight, preferably about 20% to about 45% by weight, and most preferably about 25% to 40% by weight. Preferably, the molecular weight of the polyethylene glycol is about 10,000 to about 40,000 daltons, preferably about 12,000 to about 35,000 daltons, and most preferably about 15,000 to 20,000 daltons. As used herein, "molecular weight" refers to weight average molecular weight, determined by gel permeation using polystyrene standards.

[0033] In embodiments using polyethylene glycol as the sole base polymer, it has surprisingly been found that upon challenge, the wetness indicator turns purple. It is believed that at least one of the following factors, in combination with the presence of polyethylene glycol, leads to the wetness indicator turning purple: polyethylene glycol present in the formulation in an amount of about 15% to about 45% by weight; isostearic acid present in the formulation; isostearic acid present in the formulation in an amount of about 0.5% to about 7% by weight; isostearic acid present in the formulation together with stearic acid; isostearic acid present in the formulation together with stearic acid in a weight ratio range of isostearic acid:stearic acid from 1:40 to 1:2; a combination of a hydrogenated rosin, such as Foral AX-E, and a C9 hydrocarbon resin, such as Hikotack DP-100, present in the formulation as a tackifier; or any combination of any of these factors.

[0034] Tackifying resins used in the hot melt adhesives of the present invention are those that extend adhesive properties and improve specific adhesion. As used herein, the term "tackifying resin" includes: a. Natural and modified rosins, such as gum rosin, wood rosin, tall oil rosin, distilled rosin, hydrogenated rosin, dimerized rosin, and polymerized rosin; b. Glycerol and pentaerythritol esters of natural and modified rosins, such as, for example, glycerol esters of pale wood rosin, glycerol esters of hydrogenated rosin, glycerol esters of polymerized rosin, pentaerythritol esters of pale wood rosin, pentaerythritol esters of hydrogenated rosin, pentaerythritol esters of tall oil rosin, and phenolic-modified pentaerythritol esters of rosin; c. Polyterpene resins having a softening point, as determined by ASTM method E28-58T, of about 20°C to 140°C, the latter polyterpene resins generally resulting from the polymerization of terpene hydrocarbons, such as the monoterpene known as pinene, in the presence of a Friedel-Crafts catalyst at moderately low temperatures; hydrogenated polyterpene resins are also included; d. Copolymers and terpolymers of natural terpenes, such as styrene / terpene, α-methylstyrene / terpene and vinyltoluene / terpene; e. Phenol-modified terpene resins, such as resin products resulting from the condensation of terpenes and phenols in an acidic medium; f. Oligomeric amide ester resins such as Unirez 2620 from Arizona Chemical; g. Aliphatic petroleum hydrocarbon resins having a ring and ball softening point of about 10°C to 140°C, the latter resins resulting from the polymerization of monomers consisting mainly of olefins and diolefins; hydrogenated aliphatic petroleum hydrocarbon resins are also included; examples of such commercially available resins based on this type of C5-olefin fraction are the "Wingtack 95" and "Wingtack 115" tackifying resins sold by Cray Valley US; h. Aromatic petroleum hydrocarbons and their hydrogenated derivatives; and i. Aliphatic / aromatic petroleum-derived hydrocarbons and their hydrogenated derivatives (e.g., aromatic hydrocarbon resins).

[0035] For some formulations, a mixture of two or more of the above tackifying resins may be used. A range of 15% to 75% by weight of tackifying resin may be used, with a preferred range being about 20% to about 70% by weight, preferably about 20% to 50% by weight. Examples of commercially available tackifying resins useful for the present invention include those commercially identified by the tradename Sylvalite RE 100L, a pentaerythritol-based tall oil rosin ester, and Sylvalite RE 85L, a glycerol ester of tall oil rosin, both available from Arizona Chemical Company.

[0036] Commercially available polymerized and modified rosins may be obtained from Arizona Chemical Company under the trade names "Sylvaros PR R, PR R85, and Uni-Tac 70," respectively. Commercially suitable partially hydrogenated rosins may be available from Eastman Chemical Company under the trade names "Foral AX," "Foral AXE," and "Stabelite."

[0037] The hot melt wetness indicator composition of the present invention also includes a pH adjuster so that the pH is maintained at a specific level prior to exposure to water-based body fluids. Specifically, the pH adjuster is present in an amount sufficient to bring the pH of the composition below 6, preferably between 4 and 6, and more preferably between 5 and 6. Upon exposure to such contamination by body fluids, the pH of the substrate bearing the coating changes, thereby triggering the color change effect. The pH adjuster is any molecule or composition that can be used to control the pH of the color-changing composition. The pH adjuster can be an acid, a base, or a combination of both, such as those found in buffer compositions. The pH adjuster is selected in combination with nitrazine yellow, which is used herein as a pH indicator. The pH adjuster serves to bring the pH of the hot melt wetness indicator into a range in which nitrazine yellow retains its yellow color.

[0038] Examples of suitable acidic pH adjusters include organic acids, inorganic acids, and polymeric acids; more particularly, examples of such acids include organic acids, including glycolic acid, citric acid, lactic acid, ascorbic acid, oxalic acid, maleic acid, tartaric acid, salicylic acid, palmitic acid, stearic acid, and isostearic acid, and mixtures thereof.Further examples of organic acids include polyacrylic acid, polymethacrylic acid, and copolymers containing acrylic acid, methacrylic acid, or both acrylic acid and methacrylic acid.In certain embodiments, the pH adjuster comprises, consists essentially of, or consists of stearic acid, isostearic acid, or mixtures thereof.

[0039] The amount of pH adjuster will depend on the pH of the composition without the pH adjuster and the strength of the pH adjuster. In some embodiments, the pH adjuster is present in an amount of about 5% to about 55% by weight, preferably about 10% to about 50% by weight, and most preferably about 19% to about 43% by weight. Further examples of pH adjusters can be found in U.S. Patent Application Publication No. 2011 / 0015599 to Song et al., which is incorporated herein by reference in its entirety.

[0040] The hot melt wetness indicator composition of the present invention also includes a pH indicator comprising nitrazine yellow. The amount of pH indicator is that amount necessary to readily exhibit a color change upon challenge with urine. Typically, it is present in an amount of about 0.05% to 5% by weight, preferably about 0.1% to about 2.5% by weight, and most preferably about 0.15% to 1.5% by weight. Nitrazine yellow changes color from yellow to blue upon a pH change from below 6 to above 6, most particularly above 7.2. The hot melt wetness indicator will have a pH greater than 6 upon interaction of urine and the composition. This pH is achieved in the hot melt indicator when moisture penetrates the hydrophilic organic matrix.

[0041] The pH indicator generates a visual signal discernible by the human eye under visible light to indicate that the absorbent article has been wetted with urine. The visual signal is a color change, such as from yellow, orange, or pink to blue or purple, or from colorless or essentially colorless to color, e.g., colorless to blue or purple. The pH indicator is used in an amount effective to provide the composition with a color change (or color, if the initial state is colorless) readily visible to the eye upon wetting that is distinguishable from the color of the dry composition. Particularly desirable initial starting colors (prior to the color change) include colorless, yellow, orange, green, brown, and shades and combinations thereof. The desirable final color (after the change) is preferably significantly different from the initial color. Preferred colors typically include blue, purple, and shades thereof. Figures 1(a)-1(d), described below, demonstrate some of the possible initial and final color possibilities.

[0042] The present invention may include a stabilizer or antioxidant in an amount of about 0% to about 5% by weight. Preferably, about 0.1% to 1% of stabilizer is incorporated into the composition. Stabilizers useful in the hot-melt wetness indicator adhesive compositions of the present invention are incorporated to help protect the polymer, and thereby the entire adhesive system, from the effects of thermal and oxidative degradation that typically occurs during the manufacture and application of the indicator, as well as during normal exposure of the final product to the ambient environment. Among applicable stabilizers are high molecular weight hindered phenols and polyfunctional phenols, such as sulfur- and phosphorus-containing phenols. Hindered phenols are well known to those skilled in the art and may be characterized as phenolic compounds containing sterically bulky radicals adjacent to their phenolic hydroxyl groups. In particular, a tertiary butyl group is generally substituted on the benzene ring in at least one ortho position relative to the phenolic hydroxyl group. The presence of these sterically bulky substituted radicals in proximity to the hydroxyl group serves to retard its stretching frequency and, correspondingly, its reactivity; thus, this steric hindrance provides the phenolic compounds with their stabilizing properties. Representative hindered phenols include: 1,3,5-trimethyl-2,4,6-tri(3-5-di-tert-butyl-4-hydroxybenzyl)benzene; Pentaerythritol tetrakis-3(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; n-Octadecyl-3(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; 4,4'-methylenebis(4-methyl-6-tertbutylphenol); 2,6-di-tert-butylphenol; 6-(4-hydroxyphenoxy)-2,4-bis(n-octylthio)-1,3,5-triazine; 2,3,6-tris(4-hydroxy-3,5-di-tert-butyl-phenoxy)-1,3,5-triazine; Di-n-octadecyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate; 2-(n-octylthio)ethyl-3,5-di-tert-butyl-4-hydroxybenzoate; and Sorbitol hexa-3(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

[0043] Pentaerythritol tetrakis-3(3,5-di-tert-butyl-4-hydroxyphenol) propionate is particularly preferred as a stabilizer.

[0044] The performance of these stabilizers can be further enhanced by utilizing in conjunction with them: (1) synergists, such as thiodipropionate esters and phosphites; and (2) chelating agents and metal deactivators, such as ethylenediaminetetraacetic acid, its salts, and disalicylalpropylenediimine.

[0045] The wetness indicator compositions of the present invention may contain about 1% to 30% by weight, preferably about 1% to 15% by weight, of a surfactant that renders the adhesive more hydrophilic and imparts water permeability to the composition. Surfactants suitable for use herein include cationic, anionic, or nonionic types, with nonionic types being preferred. More preferred surfactants are selected from the group of nonionic surfactants having an HLB of less than 15. These surfactants include alkylamines and amides; alkanolamines and amides; amine oxides; ethoxylated fatty alcohols, ethoxylated fatty acids, ethoxylated alkylphenols, ethoxylated amines or amides; ethoxylated fatty esters and oils; glycerol fatty esters and their ethoxylated derivatives; sorbitan derivatives; and sucrose and glucose esters and their derivatives. Most preferred surfactants have an HLB of 3 to 12 and are selected from the subgroup including ethoxylated fatty alcohols, ethoxylated fatty acids, stearic acid, glycerol esters of fatty acids and their derivatives, and sorbitan derivatives. Mixtures of two or more surfactants described hereinabove may be used for some formulations.

[0046] As used herein, the term "surfactant" or "surface-active agent" refers to any compound that reduces the surface tension when dissolved in water or an aqueous solution, or reduces the interfacial tension between two liquids, or between a liquid and a solid. Examples of suitable surfactants include, but are not limited to: a. Fatty acid esters, such as glycerol esters, PEG esters, and sorbitan esters, including ethylene glycol distearate, ethylene glycol monostearate, glycerol mono- and / or dioleate, PEG dioleate, PEG monolaurate, sorbitan monolaurate, sorbitan trioleate, etc., and these surfactants are available from ICI, Rhone-Poulenc, and other sources. b. Nonionic ethoxylates, such as alkylphenol ethoxylates, alcohol ethoxylates, alkylamine ethoxylates, including octylphenol ethoxylate, nonylphenol ethoxylate, alkylamine ethoxylate, etc. These surfactants are available from Rhone-Poulene, Union Carbide, and other sources. c. A nonionic surfactant such as 2,4,7,9-tetramethyl-5-decyne-4,7-diol available from Air Products. d. Ethylene oxide / propylene oxide copolymers available from Union Carbide, BASF, etc. Note that these and other surfactants can be blended as needed to produce the best blend of hydrophilic performance properties.

[0047] Atmer 129, glycerol monostearate, manufactured by Uniquema Corporation; Atmer 688, a nonionic surfactant blend, manufactured by ICI Americas, Inc.; and Aerosol OT 100% surfactant (dioctyl sodium sulfosuccinate), manufactured by Cytec Industries, Inc., have been found to be preferred surfactants for use in the adhesive composition.

[0048] Optionally, the hot melt wetness indicator composition may contain a plasticizer. Both water-soluble and water-insoluble plasticizers, either alone or in any desired combination, can be present in the compositions of the present invention in amounts of about 1% to about 50% by weight, preferably about 5% to about 40% by weight, and most preferably about 20% to about 35% by weight, to provide the desired viscosity control without substantially reducing the adhesive strength or use temperature of the adhesive. Both liquid and solid plasticizers can be used in the compositions of the present invention.

[0049] Water-soluble plasticizers as used herein include low molecular weight polyethylene glycols, polyfunctional alcohols, and the general class of surfactants whose molecules contain both hydrophilic and hydrophobic groups. The hydrophilic groups of the molecules generally consist of, but are not limited to, polyethylene glycol, polypropylene glycol, mono- or dihydroxyamino groups, ethoxylated amino groups, polyalkylene glycol esters of carboxyl groups, substituted or unsubstituted glycerol, glucose, sucrose, and sorbitan groups. The hydrophobic groups of the molecules generally consist of, but are not limited to, hydrocarbon groups such as alkylphenol groups, dialkylphenol groups, or linear or branched aliphatic radicals. Preferred soluble plasticizers include ethoxylated alkylphenols, ethoxylated fatty acids, and ethoxylated fatty alcohols with HLB values ranging from 8.0 to 20.0. An ethoxylated alkylphenol having an HLB value of 13.5 is available from Union Carbide Corporation of Danbury, Conn. under the trade name Triton X-100, and water-soluble ethoxylated fatty acids, such as polyethylene glycol 600 monolaurate (HLB=14.6) and polyethylene glycol 1000 dilaurate (HLB=14.2), can be purchased from Stepan Company of Northfield, Ill. under the trade names Kessco PEG 600MC and PEG 1000DL, respectively.

[0050] Suitable water-insoluble plasticizers can be selected from the group consisting of dipropylene glycol dibenzoate, pentaerythritol tetrabenzoate, polyethylene glycol 400-di-2-ethylhexanoate, 2-ethylhexyl diphenyl phosphate, butyl benzyl phthalate, dibutyl phthalate, dioctyl phthalate, various substituted citrates, and glycerates. Suitable dipropylene glycol dibenzoate and pentaerythritol tetrabenzoate can be purchased from Velsicol Chemical Company of Chicago, Ill., under the trade names "Benzoflex 9-88" and "S-552," respectively. Furthermore, suitable polyethylene glycol 400-di-2-ethylhexanoate can be purchased from C.P. Hall Company of Chicago, Ill., under the trade name "Tegmer 809." Suitable 2-ethylhexyl diphenyl phosphate and butyl benzyl phthalate may be purchased from Monsanto Industrial Chemical Company of St. Louis, Mo. under the trade designations "Santicizer 141 and 160," respectively.

[0051] Suitable plasticizers may be selected from a group including not only conventional plasticizing oils such as mineral oil, but also olefin oligomers and low molecular weight polymers, as well as vegetable and animal oils and derivatives of such oils. The petroleum-derived oils that may be utilized are relatively high-boiling temperature materials containing only a small proportion of aromatic hydrocarbons. In this regard, aromatic hydrocarbons should preferably be less than 30% by weight of the oil, more particularly less than 15% by weight. Alternatively, the oil may be completely non-aromatic. The oligomers may be polypropylene, polybutene, hydrogenated polyisoprene, hydrogenated butadiene, or similar having an average molecular weight of about 350 to about 10,000. Suitable vegetable and animal oils include glycerol esters of common fatty acids and their polymerization products. While the plasticizers found useful in the present invention can be a wide variety of plasticizers, the inventors have found that mineral oils, such as Kaydol, manufactured by Sonneborn, Inc., are particularly useful in the present invention. Benzoflex 9-88, dipropylene glycol dibenzoate, and Benzoflex 352, 1,4-cyclohexanedimethanol, both manufactured by Velsicol, have also been found to be suitable plasticizers. As will be appreciated, plasticizers are typically utilized to reduce the viscosity of the overall adhesive composition without substantially reducing the adhesive strength and / or use temperature of the adhesive. The choice of plasticizer can be useful in formulations for specific end uses (e.g., wet strength core applications). In embodiments where polyethylene glycol is used as the base polymer, the inclusion of a plasticizer has been found to increase the rate at which the color change occurs.

[0052] It should be understood that other optional additives may be incorporated into the adhesive composition of the present invention to modify specific physical properties. These may include, for example, inert colorants, such as titanium dioxide, and fillers. Typical fillers include talc, calcium carbonate, clay silica, mica, wollastonite, feldspar, aluminum silicate, alumina, hydrated alumina, glass microspheres, ceramic microspheres, thermoplastic microspheres, baryte, and wood flour.

[0053] Additionally, waxes may be added to the composition in an amount of about 1% to 50% by weight, preferably about 5% to 40% by weight.

[0054] The hot melt adhesive composition of the present invention can be prepared using any technique known in the art. A typical prior art mixing procedure involves placing all ingredients except the base polymer and wetness indicator in a jacketed mixing kettle equipped with a rotor, then raising the temperature of the mixture to dissolve the ingredients. It should be understood that the exact temperature used in this step depends on the melting point of the specific ingredients. The polymer is then introduced into the kettle with stirring, and mixing continues until a stable, homogeneous mixture is formed. Finally, preferably after a temperature reduction necessary to protect the pH indicator, the pH indicator is added, and mixing is terminated when the wetness indicator is completely dissolved in the mixture. The contents of the kettle are protected with an inert gas, such as carbon dioxide or nitrogen, during the entire mixing process.

[0055] The resulting hot melt wetness indicator can then be applied to a substrate using a variety of coating techniques. Examples include hot melt slot die coating, hot melt wheel coating, hot melt roller coating, melt blow coating, and spiral spray coating. In a preferred embodiment, the hot melt adhesive is coated onto the substrate using a slot die with a nozzle 1 to 5 mm wide, resulting in a coated pattern with multiple wetness indicator stripes on the backsheet.

[0056] The adhesive compositions of the present invention may be used in numerous nonwoven absorbent article applications, such as, for example, disposable nonwoven baby and toddler diapers, training pants, adult incontinence pads, and briefs. Such hygienic articles include a fluid-impermeable backsheet having an inner surface, a nonwoven topsheet, and an absorbent core disposed between the backsheet and the topsheet. The hot-melt wetness indicator composition of the present invention is applied to the inner surface of the backsheet and bonds thereto upon cooling and contacts the absorbent core, such that upon attack of the absorbent core by urine, the urine contacts the hot-melt wetness indicator. The hot-melt wetness indicator may also function to bond the backsheet to the absorbent core.

[0057] The hot melt wetness indicator composition includes a non-halogen-containing pH indicator that changes color upon wetting. The term "wet" or "wetted" means that the adhesive comes into contact with aqueous fluids such as urine, saline, blood, mucus and other bodily exudates, and the like.

[0058] Based on the following examples, it is believed that the use of nitrazine yellow will function adequately in any known hot-melt wetness indicating formulation that fits within the description of the composition of the present invention, i.e., a hot-melt wetness indicator composition comprising: about 1% to about 80% by weight of a base polymer; about 15% to about 75% by weight of a tackifier; and a pH adjuster in an amount sufficient to bring the pH of the composition below 6, preferably between 4 and 6, more preferably between 5 and 6, and most preferably between 5.5 and 6. Such formulations include those set forth in the examples of U.S. Pat. No. 8,828,271 and EP 1 330 272. Those formulations containing polyethylene glycol may lead to a purple color upon challenge.

[0059] Aspects of the invention Aspect 1. a base polymer in an amount of about 1% to about 80% by weight; about 15% to about 75% by weight of a tackifier; a pH adjuster in an amount sufficient to bring the pH of the composition to less than 6, preferably between 4 and 6, more preferably between 5 and 6, and most preferably between 5.5 and 6; and A pH indicator comprising about 0.01% by weight to about 5% by weight of nitrazine yellow. 1. A hot melt wetness indicator composition comprising:

[0060] Aspect 2. the base polymer is present in an amount of about 1% to about 45% by weight, preferably about 1% to 40% by weight; the tackifier is present in an amount of about 20% to about 70% by weight, preferably about 20% to about 50% by weight; the pH adjuster is present in an amount of from about 5% to about 55% by weight, preferably from about 10% to about 50% by weight, and most preferably from about 19% to about 43% by weight; and the pH indicator is present in an amount of from about 0.04% to about 2.5% by weight, preferably from about 0.05% to about 1.5% by weight, and most preferably from about 0.07% to about 1% by weight; The composition of embodiment 1.

[0061] Embodiment 3. The composition of embodiment 1 or 2, wherein the base polymer is water soluble.

[0062] Embodiment 4. The composition of any one of embodiments 1 or 2, wherein the base polymer is selected from the group consisting of ethylene vinyl acetate (EVA), styrene-isoprene-styrene (SIS) block copolymer, styrene-butadiene-styrene (SBS) block copolymer, styrene-ethylene-butylene-styrene (SEBS) block copolymer, styrene-ethylene / ethylene-propylene-styrene (SEEPS) block copolymer, high density polyethylene, low density polyethylene, chemically modified polyethylene, sulfonated polyester, polyvinylpyrrolidone, polyvinylpyrrolidone / vinyl acetate copolymer, amorphous polyalphaolefin, ethylene / styrene interpolymer (ESI), metallocene-catalyzed APAO, polyvinyl methyl ether, and polyethylene glycol, and mixtures thereof.

[0063] Embodiment 5. The composition of any one of embodiments 1 or 2, wherein the base polymer comprises polyethylene glycol.

[0064] Embodiment 6. The composition of any one of embodiments 1 or 2, wherein the base polymer comprises polyethylene glycol.

[0065] Embodiment 7. The composition of embodiment 5 or 6, wherein the base polymer is present in an amount of about 10% to about 55% by weight, preferably about 20% to about 45% by weight, and most preferably about 25% to about 40% by weight.

[0066] Aspect 8. The composition of any one of Aspects 1-7, wherein the tackifier is selected from the group consisting of natural rosin, modified rosin, hydrogenated rosin, polyterpene resins, copolymers of natural terpenes, terpolymers of natural terpenes, phenolic-modified terpene resins, oligomeric amide ester resins, aliphatic petroleum hydrocarbon resins, aromatic hydrocarbon resins, and hydrogenated derivatives of said aromatic hydrocarbon resins, and mixtures thereof.

[0067] Embodiment 9. The composition of any one of embodiments 1-7, wherein the tackifier is selected from the group consisting of hydrogenated rosin, aromatic hydrocarbon resin, and hydrogenated derivatives of the aromatic hydrocarbon resin, and mixtures thereof.

[0068] Embodiment 10. The composition of any one of embodiments 1-9, further comprising a surfactant in an amount of about 1% to about 30% by weight, preferably about 4% to 15% by weight.

[0069] Embodiment 11. The composition of embodiment 10, wherein the surfactant is a nonionic surfactant, a cationic surfactant, or an anionic surfactant.

[0070] Aspect 12. The composition of aspect 11, wherein the surfactant is a nonionic surfactant and is selected from the group consisting of alkylamines and amides, alkanoamines and amides, amine oxides, ethoxylated fatty alcohols, ethoxylated fatty acids, ethoxylated alkylphenols, ethoxylated amines and amides, ethoxylated fatty esters and oils, glycerol fatty esters and their ethoxylated derivatives, sorbitan derivatives, sucrose esters and glucose esters, and derivatives thereof.

[0071] Embodiment 13. The composition of any one of embodiments 1-12, further comprising a plasticizer in an amount of about 1% to about 15% by weight, preferably about 1% to 10% by weight, and most preferably about 1% to 7% by weight.

[0072] Embodiment 14. The composition of embodiment 13, wherein the plasticizer is a water-insoluble plasticizer.

[0073] Embodiment 15. The composition of any one of embodiments 1-14, further comprising a wax.

[0074] Embodiment 16 The composition of any one of embodiments 1-15, further comprising a stabilizer or antioxidant.

[0075] Embodiment 17. The composition of any one of embodiments 1-16, further comprising a filler selected from the group consisting of talc, calcium carbonate, clay silica, mica, wollastonite, feldspar, aluminum silicate, alumina, hydrated alumina, glass microspheres, ceramic microspheres, thermoplastic microspheres, barite, and wood flour.

[0076] Embodiment 18. The composition of any one of embodiments 1-17, wherein the pH adjuster is selected from the group consisting of glycolic acid, citric acid, lactic acid, ascorbic acid, oxalic acid, maleic acid, tartaric acid, salicylic acid, palmitic acid, stearic acid, and isostearic acid, and mixtures thereof.

[0077] Embodiment 19. The composition of any one of embodiments 1-17, wherein the pH adjuster is selected from the group consisting of stearic acid, isostearic acid, and mixtures thereof.

[0078] Aspect 20. a fluid impervious backsheet having an interior surface, a nonwoven topsheet, and an absorbent core disposed between the backsheet and the topsheet; and a hot melt wetness indicator bonded to the interior surface of the backsheet and in contact with the absorbent core such that upon attack of the absorbent core by urine, the urine contacts the hot melt wetness indicator; 1. A hygiene article comprising: about 1% to about 80% by weight of a base polymer; about 15% to about 75% by weight of a tackifier; a pH adjuster in an amount sufficient to bring the pH of the composition to less than 6, preferably between 4 and 6, more preferably between 5 and 6, and most preferably between 5.5 and 5; and A pH indicator comprising about 0.01% by weight to about 5% by weight of nitrazine yellow. Hygiene articles, including: [Example]

[0079] The following examples demonstrate some aspects of certain preferred embodiments of the invention and are not to be construed as limiting thereof.

[0080] Four formulations (referred to as formulations 1(a) to 1(d)) were prepared and the test results are shown in Figures 1(a) to 1(d). The formulations were as follows:

[0081] Formulation 1(a) - Polyethylene glycol having a molecular weight of approximately 20,000 daltons was used as the single base polymer in an amount of 30% by weight; a blend of hydrogenated rosin and aromatic hydrocarbon resin was used as the tackifier in an amount of 49% by weight; a blend of stearic acid (18%) and itaconic acid (2%) was used as the pH adjuster in an amount of 20% by weight; an antioxidant was used; and nitrazine yellow was used as the pH indicator in an amount of 0.18% by weight.

[0082] Formulation 1(b) had a base polymer other than polyethylene glycol; a tackifier; stearic acid as a pH adjuster; an antioxidant; a surfactant; and nitrazine yellow in an amount of 0.34 wt %.

[0083] Formulation 1(c) was similar to Example 8 of U.S. Patent No. 8,828,271, except that it contained no fluorescent agent and contained nitrazine yellow. Specifically, Formulation 1(c) contained 28 wt. % Polyglycol 20000S as the sole base polymer; 43 wt. % Sylvaros TP 2040 as a tackifier; 8 wt. % Benzoflex 9-88 as a plasticizer; 20 wt. % Century 1224 as a pH adjuster; and 0.2 wt. % Nitrazine Yellow.

[0084] Formulation 1(d) was similar to Example 9 of U.S. Patent No. 8,828,271, except that it contained no fluorescent agent and contained nitrazine yellow. Specifically, Formulation 1(d) contained 36 wt. % Polyglycol 20000S as the sole base polymer; 35 wt. % Sylvaros TP 2040 as a tackifier; 13 wt. % Benzoflex 352 as a plasticizer; 20 wt. % Century 1224 as a pH adjuster; and 0.2 wt. % Nitrazine Yellow.

[0085] Century 1224 is a saturated fatty acid product containing approximately 70 percent C18 stearic acid and typically has 23 percent methyl-branched C18 saturated acids.

[0086] Polyglykol 20000S is a polyethylene glycol with an average molecular weight of 20000. It is a solid in flake form.

[0087] Silvaros TP 2040 is a terpene phenolic resin used as a tackifier.

[0088] Benzoflex 9-88 is a highly solvating plasticizer.

[0089] Benzoflex 352 is a solid plasticizer with a melting point of 118°C.

[0090] Nitrazine yellow is a pH indicator dye. Nitrazine indicates a pH range of 4.5 to 7.5 and is usually used as the disodium salt.

[0091] The coated laminate was produced by coating a 25 gsm blended melt (90.5°C) hot melt wetness indicator onto a breathable polymer film (BR-149) using a continuous 5 mm wide slot nozzle. The indicator strip on the breathable film was then bonded to a release liner at a line speed of 100 fpm.

[0092] The humidity resistance of Formulations 1(a) and 1(b) was tested by stapling a section (25 gsm) of each coated condition to a white board, placing it in a humidity chamber at 40°C and 80% relative humidity, and examining it for any change in color. Both formulations exhibited stable color for over three weeks.

[0093] The color change rate was tested by dropping Sensitive Eyes® saline solution (from Bausch & Lomb, Inc.) onto the coated, fully cooled laminate and measuring how long it took for the color change to become noticeable and the time for the complete color change. The test was then repeated using a new, dried section of the coated laminate and tested with a synthetic urine solution. The results are shown in Figures 1(a)-1(d). As shown, the strip with Formulation 1(a) went from yellow to purple; the strip with Formulation 1(b) went from essentially colorless to blue; the strip with Formulation 1(c) went from pale yellow to a dull blue; and the strip with Formulation 1(d) went from pale yellow to a dull blue. The time to color change results were less than two minutes. Preferred embodiments are capable of instantaneous color change.

[0094] Color was determined using software. Photographs were taken initially (one day after the laminate was produced) and 5 minutes after the addition of the saline solution. Publicly available software from Pantone LLC (https: / / www.pantone.com / color-finder) was used to best match / assign the color to a Pantone color. This website allows users to input colors via sRGB, Hex, or CMYK nomenclature to find the best match. Representative sRGB colors were determined from the photographs shown in Figures 1(a)-1(d) and matched to their Pantone equivalents. A classification of the color change can be seen in Table 1 below. The "Start" color is the average of the entire strip where the hot melt wetness indicator was applied. The "After" color is the average of the dark areas corresponding to where the saline droplet was placed, excluding the edges of the droplet where a noticeable change in droplet color occurs.

[0095] [Table 1]

[0096] When a range of values is provided, it is understood that each intervening value, and any combination or subcombination of intervening values between the upper and lower limits of that range and any other stated or intervening value within that range, is included within the recited range of values. In addition, the present invention includes a range of components that is the lower limit of a first range and the upper limit of a second range for that component. Furthermore, whenever a component (such as a base polymer or tackifier) is discussed herein, "a" component includes a single such component, a blend of various grades of that component, or a blend of various types of that component.

[0097] Unless otherwise defined, all technical and scientific terms used herein generally have the same meaning as understood by one of ordinary skill in the art to which this invention belongs. All publications and patents specifically mentioned herein are incorporated by reference in their entirety for all purposes, including the description and disclosure of chemicals, instruments, statistical analyses, and methodologies reported in the publications that may be used in connection with the present invention. All references cited herein are to be construed as indicative of the level of skill in the art. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such disclosure by prior invention.

[0098] Although illustrated and described herein with reference to certain specific embodiments, the invention is nevertheless not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the spirit of the invention.

Claims

1. 1. A hot melt wetness indicator composition comprising: 1% to 80% by weight of a base polymer; 15% to 75% by weight of a tackifier; a pH adjuster in an amount sufficient to provide a pH of the composition of less than 6; and A pH indicator consisting of 0.01% to 5% by weight of nitrazine yellow A composition comprising:

2. the base polymer is present in an amount of 1% to 45% by weight; the tackifier is present in an amount of 20% to 70% by weight; the pH adjuster is present in an amount of 5% to 55% by weight; and the pH indicator is present in an amount of 0.04% to 2.5% by weight; The composition of claim 1.

3. The composition of claim 1 , wherein the base polymer is water soluble.

4. 2. The composition of claim 1, wherein the base polymer is selected from the group consisting of ethylene vinyl acetate (EVA), styrene-isoprene-styrene (SIS) block copolymer, styrene-butadiene-styrene (SBS) block copolymer, styrene-ethylene-butylene-styrene (SEBS) block copolymer, styrene-ethylene / ethylene-propylene-styrene (SEEPS) block copolymer, high density polyethylene, low density polyethylene, chemically modified polyethylene, sulfonated polyester, polyvinylpyrrolidone, polyvinylpyrrolidone / vinyl acetate copolymer, amorphous polyalphaolefin, ethylene / styrene interpolymer (ESI), metallocene-catalyzed APAO, polyvinyl methyl ether, and polyethylene glycol, and mixtures thereof.

5. The composition of claim 1 , wherein the base polymer comprises polyethylene glycol.

6. The composition of claim 1 wherein the base polymer comprises polyethylene glycol.

7. The composition of claim 6, wherein the base polymer is present in an amount of from 10% to 55% by weight.

8. 2. The composition of claim 1, wherein the tackifier is selected from the group consisting of natural rosin, modified rosin, hydrogenated rosin, polyterpene resins, copolymers of natural terpenes, terpolymers of natural terpenes, phenolic-modified terpene resins, oligomeric amide ester resins, aliphatic petroleum hydrocarbon resins, aromatic hydrocarbon resins, and hydrogenated derivatives of said aromatic hydrocarbon resins, and mixtures thereof.

9. 10. The composition of claim 1, wherein said tackifier is selected from the group consisting of hydrogenated rosin, aromatic hydrocarbon resins, and hydrogenated derivatives of said aromatic hydrocarbon resins, and mixtures thereof.

10. The composition of claim 1 further comprising a surfactant in an amount of 1% to 30% by weight.

11. The composition according to claim 10, wherein the surfactant is a nonionic surfactant, a cationic surfactant, or an anionic surfactant.

12. 12. The composition of claim 11, wherein the surfactant is the nonionic surfactant and is selected from the group consisting of alkylamines and amides, alkanoamines and amides, amine oxides, ethoxylated fatty alcohols, ethoxylated fatty acids, ethoxylated alkylphenols, ethoxylated amines and amides, ethoxylated fatty esters and oils, glycerol fatty esters and their ethoxylated derivatives, sorbitan derivatives, sucrose esters and glucose esters and derivatives thereof.

13. The composition of claim 1 further comprising a plasticizer in an amount of 1% to 15% by weight.

14. The composition of claim 13, wherein the plasticizer is a water-insoluble plasticizer.

15. The composition of claim 1 further comprising a wax.

16. The composition of claim 1 further comprising a stabilizer or antioxidant.

17. 10. The composition of claim 1, further comprising a filler selected from the group consisting of talc, calcium carbonate, clay silica, mica, wollastonite, feldspar, aluminum silicate, alumina, hydrated alumina, glass microspheres, ceramic microspheres, thermoplastic microspheres, barite, and wood flour.

18. 10. The composition of claim 1, wherein the pH adjuster is selected from the group consisting of glycolic acid, citric acid, lactic acid, ascorbic acid, oxalic acid, maleic acid, tartaric acid, salicylic acid, palmitic acid, stearic acid, and isostearic acid, and mixtures thereof.

19. 10. The composition of claim 1, wherein the pH adjuster is selected from the group consisting of stearic acid, isostearic acid, and mixtures thereof.

20. a fluid impervious backsheet having an interior surface, a nonwoven topsheet, and an absorbent core disposed between the backsheet and the topsheet; and a hot melt wetness indicator attached to the interior surface of the backsheet and in contact with the absorbent core, such that upon attack of the absorbent core by urine, urine contacts the hot melt wetness indicator; 1. A hygiene article comprising: 1% to 80% by weight of a base polymer; 15% to 75% by weight of a tackifier; a pH adjuster in an amount sufficient to provide a pH of the composition of less than 6; and A pH indicator consisting of 0.01% to 5% by weight of nitrazine yellow Hygiene articles, including:

Images