Surgery – Means and methods for collecting body fluids or waste material – Absorbent pad for external or internal application and...
Reexamination Certificate
1999-04-09
2003-11-25
Lo, Weilun (Department: 3761)
Surgery
Means and methods for collecting body fluids or waste material
Absorbent pad for external or internal application and...
C604S389000, C524S275000, C524S320000, C524S603000
Reexamination Certificate
active
06653522
ABSTRACT:
BACKGROUND OF THE INVENTION
Hot melt adhesives, 100% solids materials, which are applied to a substrate when molten and cooled to harden the adhesive layer, are used commercially for a wide variety of applications. The major advantage of hot melt adhesive systems is the lack of a carrier fluid which eliminates the need for drying the adhesive film once it is applied to the substrate. This elimination of the drying step overcomes hazards associated with solvent usage and also allows for faster production line speeds and lower transportation costs.
For various applications, it is also desired that some hot melt adhesives be hydrophilic, i.e., be water-soluble, water-sensitive or water-activated. Such hydrophilic adhesives find use, for example, in moisture activated envelope adhesives and in the construction of flushable disposable products including diapers and sanitary napkins where they promote the disintegration of the disposable article in water.
Hot melt adhesives have historically been based on petroleum derived polymers such as polyethylene, ethylene-vinyl acetate, styrenic block copolymers and polypropylene. Water sensitive hot melts have also been prepared from vinyl pyrrolidone polymers including vinyl acetate/vinyl pyrrolidone copolymers. All these adhesive compositions are further tackified, plasticized and/or reinforced with a variety of resins, oils and/or waxes which are derived from both petroleum and naturally occurring feedstocks such as wood, gum and tall oil rosin and terpenes.
In the production of disposable articles, hot melt adhesives are typically extruded at elevated temperatures (about 250° F. to 350° F.) directly onto a work piece, typically a polyethylene or polypropylene film, a nonwoven fabric, an absorbent material, a tissue, or a film which can then be bonded to another nonwoven fabric, absorbent material, tissue, or film using the hot melt adhesive. Application of the adhesive may be extruded by fine line, multi-dot, multi-line methods or spray techniques. The hot melt adhesive is used to laminate layers or attach elastic, particularly for waist or leg band closures for disposable diapers.
In such disposable products, it is desirable to know if the product has become wet with water or urine. For example, it may not be readily apparent that a diaper has become wet due to the plastic coating or water proof panty worn over the diaper.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a hot melt adhesive composition which is capable of indicating the presence of water or urine therein and to disposable products comprising such adhesives. Specifically, the hot melt adhesives of the present invention change color in response to water or urine.
The hot melt adhesives of the present invention comprise a pH adjusting component and an indicating agent which is capable of changing color in response to changes in pH.
DETAILED DESCRIPTION OF THE INVENTION
The adhesives of the present invention comprise a pH adjusting component and an indicating agent which is capable of changing color in response to changes in pH.
The indicating agent is a component which is capable of changing color in response to changes in pH. Acid-base indicators are preferred because they change color rapidly. The most preferred indicating agents are those which change to a bright, vivid color. The acid-base indicators for use herein are those which change color at a pH in the range of about 3 to 7, such as Ethyl Red, Bromophenol Blue (made by Eastman Kodak), Bromocresol Green mixed with Bromophenol Blue, or Bromophenol Blue. Most preferred is Bromocresol Green which changes color in the range pH 3.8 to 5.4.
The indicating agent is used in an amount effective to provide the composition with a readily visible color when the composition exposed to water or urine; generally about 0.05 to 0.1 weight percent indicator, based on the weight of the composition. Preferably, the indicating agent is present in amounts of 0.005 to 3% by weight of the adhesive composition.
The adhesives of the present invention also comprise a pH adjusting agent which is an acidic or basic component which changes the pH of the hot melt adhesive. Preferred are acidic plasticizers which have an acidic functional end group, such as a carboxylic acid. Examples of such acidic plasticizers include isostearic acid, azelaic acid, stearic acid, oleic acid, linoleic acid, ricinoleic acid and dimer acid. Isostearic acid is preferred.
The acid plasticizer is used to render the resulting adhesive acidic. As used herein, acidic is defined as a pH less than the indicating range of the indicating agent. The adhesives described herein, without the acidic plasticizer, are of a pH such that the addition of Bromocresol Green (or any indicating agent) to the adhesive causes the indicator to change. Therefore, it was found in accordance with the present invention, that the addition of an acidic plasticizer adjusts the pH of the adhesive to below the activation range of the indicating agent, preventing the indicating agent from changing color unless exposed to a substance that will raise the pH, such as water or urine, as will be described below.
Specifically, the addition of urine, which has a pH is the range 5.8 to 7.4, or the addition of water with a pH of 7, to the adhesive, causes the pH of the adhesive to increase, passing through the indicator range, causing a color change signaling that the adhesive is wet with water or urine. The pH range of urine is disclosed in J. L. Hammone, et al. TAPPI Int. Dissolving Pulps Conf. (Geneva) Proc.: 247-264 (Mar. 24-27, 1987).
Any indicating agent capable of changing color in response to a change in pH may be used. Therefore when formulating an adhesive in accordance with the present invention, the acidic plasticizer and indicating agent are chosen so that the pH of the adhesive is such that when urine or water are added, the pH changes in such a way that the indicator is activated.
The pH adjusting agent and indicating agent are formulated into an adhesive composition. Any base polymer for hot melt adhesives may be used such as polyethylene, ethylene-vinyl acetate, styrenic block copolymers, polypropylene, and vinyl pyrrolidone polymers including vinyl acetate/vinyl pyrrolidone copolymers. Preferably the base polymer is a sulfonated polyester. In this embodiment, the present invention is directed to hot melt adhesive compositions comprising (a) 20 to 80% by weight of a sulfonated polyester; (b) 3 to 30% by weight of a pH adjusting agent, particularly an acidic plasticizer; and (c) to 0.05 to 3% by weight of an indicating agent capable of changing color in response to changes in pH.
The major component of the adhesive of the invention, present in an amount of 20 to 80% by weight of the adhesive, is a sulfonated polyester condensation polymer comprising the reaction product of:
(a) at least one difunctional dicarboxylic acid or corresponding methyl ester which is not a sulphomonomer;
(b) 2 to 25 mole percent of at least one sulphomonomer containing at least one metallic sulfonate group or nitrogen-containing non-metallic sulfonate group attached to an aromatic or cycloaliphatic nucleus and at least one functional group selected from the group consisting of hydroxyl, carboxyl, and amino;
(c) at least one difunctional reactant selected from a glycol or a mixture of a glycol and diamine having two —NRH groups, the glycol containing two —C(R
1
)
2
—OH groups wherein R in the reactant is hydrogen or an alkyl group of 1 to 6 carbon atoms, and R
1
in the reactant is a hydrogen atom, an alkyl of 1 to 5 carbon atoms, or an aryl group of 6 to 10 carbons atoms;
(d) 0 to 40 mole percent of a difunctional reactant selected from hydroxycarboxylic acids having one —C(R)
2
—OH group, aminocarboxylic acids having one —NRH group, amino-alcohols having one —C(R)
2
—OH group and one —NRH group, or mixtures of said difunctional reactants wherein R in the reactant is hydrogen or an alkyl group of 1 to 6 carbon atoms; and
(e) 0 to 40 mole percent of a multifunctional reactant containing at le
Blumenthal Mitchell J.
Paul Charles W.
Foulke Cynthia L.
National Starch and Chemical Investment Holding Corporation
LandOfFree
Hot melt adhesives based on sulfonated polyesters comprising... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hot melt adhesives based on sulfonated polyesters comprising..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hot melt adhesives based on sulfonated polyesters comprising... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3163962