Surgery – Means and methods for collecting body fluids or waste material – Absorbent pad for external or internal application and...
Reexamination Certificate
1997-08-25
2001-08-21
Ruhl, Dennis (Department: 3761)
Surgery
Means and methods for collecting body fluids or waste material
Absorbent pad for external or internal application and...
C604S368000, C604S369000, C604S370000
Reexamination Certificate
active
06277104
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to sanitary protection products such as sanitary napkins, panty liners, incontinence products, diapers, surgical dressings and bedding underpads. In particular, this invention relates to air permeable, liquid impermeable barrier structures for such products.
BACKGROUND OF THE INVENTION
Sanitary protection products, such as sanitary napkins, panty liners, incontinence products, diapers and bedding underpads, are typically comprised of a body facing, liquid permeable cover, a garment facing, substantially liquid impermeable barrier sheet and an absorbent structure therebetween. The liquid impermeable barrier sheet is typically made of a thin, flexible plastic film that is impermeable to both liquids and vapors. The liquid permeable cover is also quite often made of a plastic film, similar to that of the barrier sheet, that is made perforate by creating two or three dimensional perforations in the film, thereby leaving plastic film land areas between the perforations. Such barrier sheets, as well as the land areas of the liquid permeable plastic film covers, do not permit vapors of liquids absorbed in the product to pass out from the product or permit liquids that collect on the surface of the user's body to enter into the product, the liquids being such as menstrual fluids, urine and perspiration. Such products typically feel uncomfortably hot when dry and clammy when wet.
Prior inventors have attempted to facilitate the transmission and removal of vapors from absorbent products by using inherently vapor transmitting liquid barrier materials or by creating, in liquid barrier materials, pores that are large enough to permit passage of vapors but not the passage of liquids. Such materials, and the products made therefrom, are commonly described as “breathable”. Vapor permeable pores may be grouped into two categories, micropores and macropores, these being contained in microporous and macroporous materials respectively. Microporous materials are most resistant to liquid penetration and exhibit Frazier air permeability values of zero mm
3
/m
2
/min. However, they are also most resistant to vapor permeation, and therefore likely to be perceived by the user as not being breathable and not providing comfort and a dry feeling during wear. Macroporous materials, on the other hand, are most likely to be perceived as being breathable, exhibiting Frazier air permeability values that are greater than zero mm
3
/m
2
/min, thereby providing such comfort and dry feeling; but are also most likely to permit liquids to leak and therefore not provide protection against leakage from the absorbent product onto the user, the user's garment and beddothes.
Microporous Structures
Microporous structures are for the most part films with effective vapor transmitting micropore sizes that are equal to or greater than 100 Angstroms. Films may be inherently microporous, as for example those films made of polyurethanes. Such a film formed onto a base woven or nonwoven fabric is described in U.S. Pat. No. 4,560,611, where the coating solution consists of a polar organic solvent containing a polyurethane elastomer, a water repellent agent, e.g., a fluorine or silicone based material, a polyisocyanate and a nonionic surfactant. U.S. Pat. No. 4,197,371 discloses a sheet material of natural or synthetic rubber or a rubberlike polymer having uniformly incorporated particles of at least one swellable modified polymer such as modified starches and celluloses. U.S. Pat. No. 4,178,271 discloses a similar sheetlike material where the film is polyvinyl chloride or its copolymer. U.S. Pat. No. 3,869,310 discloses a leatherlike flexible sheet material, comprising a nonwoven fibrous mat and a polymeric impregnant, that has a porous structure and is not bonded to the fibers of the mat. The mat, composed of fibers prepared from at least two different polymeric materials, is first impregnated with a first liquid, that is a solvent for one of the polymeric materials and a nonsolvent for the other, to dissolve the soluble fibers; and then adding a second liquid, that is partially miscible with the first liquid and is a nonsolvent for all the polymeric fiber materials, to coagulate the resulting polymer solution.
Pores may be created in inherently nonporous films by means such as: stretching films in which thinned or stressed regions have been created or which noncompatible (to the film) inclusions have been incorporated. The stretching cause microfissures to form in the thinned or stressed regions or microseparations to form between the film and the noncompatible inclusions. Other means to create micropores comprise the incorporation in a film of soluble or volatile indusions that are removed by dissolving or volatilizing such inclusions. Still other means provide the blending into a polymer of fragmentable or abradable particles to form a sheet and then subjecting the sheet to a compressive force that breaks the particles to form micropores or to abrade the sheet to form micropores. UK Patent Application GB No 2,026,381 discloses the preparation of porous membranes by blending a polymer with a liquid component to form a binary two-phase system which in the liquid aggregate state has regions that are miscible and regions that have miscibility gaps. UK Patent Application GB No 2,115,702B discloses a liquid impermeable, vapor permeable backing that is composed of a film made by molding a mixture of a polyolefin resin and a liquid or waxlike hydrocarbon polymer into a film and then stretching the film laterally and/or longitudinally to more than 1.2 times its original dimension to create fine pores in the film. U.S. Pat. Nos. 3,953,566, 3,962,153, 4,096,227, 4,110,392, 4,187,390 and 4,194,041 disclose the preparation of porous sheets, and other porous articles, by extruding a paste comprised of particles of polytetrafluoroethylene, which is a nonthermoplastic polymer, and a lubricant, and then removing the lubricant and stretching and annealing the resultant product. The resulting product is a sintered, oriented porous film characterized by having polymer nodes connected by fibrils. Somewhat related to these patents, and yielding a soft dothlike liquid permeable sheet material, is U.S. Pat. No. 4,622,036 which discloses such a sheet material consisting of particles of nondissolvable polyolefin or polyvinyl chloride that are partially fused together by heat so as to provide a desired amount of liquid permeability, the particles ranging in size from about one to 2000 microns, and the sheet having a thickness from about 0.0005 to 250 inches.
U.S. Pat. Nos. 4,100,238 and 4,197,148 describe the preparation of microporous films by extruding a two component blend from which one component is leached out with a solvent, and then stretching the leached film to obtain a desired porosity in a soft dothlike liquid permeable sheet material. U.S. Pat. Nos. 3,214,501, 3,640,829 and 3,870,593 disclose the preparation of a microporous polymer sheet by blending into a polymer nonmiscible, nonleachable fillers such as starch and salts, forming the sheet and then stretching the sheet to form pores that are initiated at the sites of the filler particles. U.S. Pat. No. 4,347,844 discloses the preparation of a porous sheet, for use in a disposable diaper, by blending a particulate substance into a polymer, forming a sheet and then breaking the particulate substance within the sheet under a compressive force to create micropores. U.S. Pat. No. 4,308,303 discloses a flocked foam coated fiber reinforced water vapor permeable barrier, having a fabric appearance and capable of filtering bacteria, comprising a microporous polyolefin film coated on at least one surface with a foamed latex polymer, flocked fibers on the outside of the foamed latex polymer and a web of spunbonded fibers on the outside of the flocked foamed latex polymer. The film is rendered microporous by stretching. The film becomes microporous because it has minute fracture sites or pore nucleating agents such as finely divided filler, pref
Ciesielski Mary Gail
Lasko Vincent Paul
Mc-Neil-PPC, Inc.
Ruhl Dennis
LandOfFree
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