Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1996-03-19
2001-09-18
Reddick, Judy M. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S151000, C524S292000, C524S297000, C524S317000, C524S270000, C524S272000, C524S377000
Reexamination Certificate
active
06291562
ABSTRACT:
1. FIELD OF THE INVENTION
The present invention relates to water sensitive hot melt adhesive compositions and more particularly, to a water sensitive hot melt adhesive composition which finds utility in the manufacture of disposable soft goods such as diapers, feminine napkins and the like.
2. BACKGROUND OF THE INVENTION
The prior art is replete with numerous examples of hot melt adhesives which are employed for the construction of disposable soft goods. An example of a suitable hot melt adhesive for this purpose is disclosed in detail in U.S. Pat. No. 5,149,741 to Alper et al. Further, it is noted in that reference, that the prior art methods of application of these prior art adhesives have included, but are not limited to, extrusion [multi-bead or slot], spray or wheel application systems.
While the prior art hot melt adhesive compositions utilized heretofore have operated with varying degrees of success, they have shortcomings which have detracted from their usefulness. For example, and while disposable garments such as incontinent briefs and disposable diapers have gained wide acceptance and are convenient and easy to utilize, concerns have been expressed regarding the environmental impact of such garments once they have become unserviceable or soiled and thereafter disposed of in landfills or the like.
As should be understood, no readily convenient method is now available for recycling, or otherwise separating the components of a nonwoven object of interest such as a disposable diaper into its component parts whereby the components may be recycled or alternatively disposed of in an environmentally friendly manner thus reducing any adverse impact these objects may have.
3. OBJECTS AND SUMMARY OF THE INVENTION
It is therefore the object of the present invention to provide an improved water sensitive hot melt adhesive composition which is uniquely well suited for the manufacture of disposable soft goods.
It is a further object of the present invention to provide a water sensitive hot melt adhesive composition which can be employed as either a single or multi-purpose adhesive and which further can be applied by utilizing either extrusion or spray techniques to at least one polyolefin, or nonwoven substrate, and at least one other elastic, polyolefin, nonwoven, tissue or release liner substrate thereby forming a laminate.
Another object of the present invention is to provide a water sensitive hot melt adhesive which finds utility in the assembly of a disposable soft good and which has the following composition:
(a) about 5% to about 95%, by weight, of a poly (vinyl methyl ether);
(b) about 5% to about 70%, by weight, of a tackifying resin;
(c) about 5% to about 35%, by weight, of a water soluble plasticizer; and
(d) about 0.1% to about 3%, by weight, of a antioxidant/stabilizer and wherein the water sensitive hot melt adhesive composition solubilizes at a predetermined rate when exposed to water.
Another object of the present invention is to provide a water sensitive hot melt adhesive composition which can be employed in connection with the manufacture of disposable soft goods, and wherein the hot melt adhesive composition has an excellent dry bond strength, but which can be induced to delaminate thereby permitting the component elements of the disposable soft good to be recycled or otherwise disposed of in an environmentally friendly manner.
Another object of the present invention is to provide a water sensitive hot melt adhesive composition which produces a dry bond strength which is substantially equal to that produced by the prior art adhesive compositions.
Another object of the present invention is to provide a water sensitive hot melt adhesive composition which has a viscosity of less than about 60,000 cP at 325° F., and which further does not increase in viscosity or gel even under prolonged heat aging at normal application temperatures.
Another object of the present invention is to provide a water sensitive hot melt adhesive composition which possesses an excellent balance of high specific adhesion, elevated temperature resistance and acceptable cohesive strengths at a relatively low viscosity.
Another object of the present invention is to provide a water sensitive hot melt adhesive composition which is operable to degrade at a predetermined rate when exposed to water or urine, and wherein the adhesive when incorporated into a nonwoven garment or disposable soft good maintains the garment in an assembled state during its normal use notwithstanding exposure to urine or water.
Another object of the present invention is to provide a water sensitive hot melt adhesive composition which displays enhanced spraying characteristics when compared to similar water soluble hot melt adhesive compositions.
Further objects and advantages of the present invention are to provide a water sensitive hot melt adhesive composition for the purposes described, and which is durable, easy to apply, by utilizing conventional manufacturing techniques, and which further does not have the shortcomings attributable to the prior art adhesives utilized heretofore.
REFERENCES:
patent: 3345320 (1967-10-01), Uffner et al.
patent: 4033918 (1977-07-01), Hauber
patent: 5080978 (1992-01-01), Kulzick et al.
patent: 5252646 (1993-10-01), Iovine et al.
patent: 5330832 (1994-07-01), Liu
patent: 5356963 (1994-10-01), Kauffman et al.
patent: 5385965 (1995-01-01), Bernard et al.
patent: 5387623 (1995-02-01), Ryan et al.
patent: 5527845 (1996-06-01), Strelow et al.
Andrus Sceales Starke & Sawall LLP
Bostik Findley, Inc.
Reddick Judy M.
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