Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Carbohydrate doai
Reexamination Certificate
2000-05-11
2002-09-03
Peselev, Elli (Department: 1623)
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Carbohydrate doai
C502S404000, C536S123100, C536S124000, C604S367000
Reexamination Certificate
active
06444653
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a particulate absorbent, for the absorption of liquids, comprising particles selected from the group consisting of particles of glass-like polysaccharides and of particles of glass-like polysaccharides occluding, in their internal structure, at least one surfactant.
The present invention further relates to the use of the latter particulate absorbent alone or in combination with additives or intrants, as absorbent of polar liquids and of physiological fluids and more particularly relates to specific absorbent compositions of the particulate absorbent according to the invention with selected carboxymethylcelluloses and/or with selected gums.
The present invention also concerns absorbent combinations of a predetermined amount of at least one particulate absorbent and/or of a predetermined amount of at least one absorbent composition with a suitable carrier.
BACKGROUND
Various glass-like polysaccharides are known in the art. For example U.S. Pat. No. 5,360,903 describes glass-like polysaccharides and glass-like starches having a substantially occluded water component. Such polysaccharides are useful for abrading surfaces.
Diapers and more particularly sanitary napkins are traditionally constituted by a first external layer permeable to physiological fluids, a central matrix essentially made of an absorbing material such as cloth, cotton, paper wadding or batts of cellulose fibre and a second external layer impermeable to physiological fluids and to aggregates formed by the physiological fluids with the absorbing material present in the central matrix. The central matrix is entrapped between both layers. The central matrix of diapers, originally essentially made of pads of fluffed cellulose pulp fibres, have over a time span of about 20 years gradually been substituted by synthetic absorbent polymers and by synthetic superabsorbent polymers in the form of a hard, dry, granular powder. A detailed description of such absorbent is given in Modem Superabsorbent Polymer Technology, by Frederic L. Buchholz and A. T. Graham, edited by Wiley-VCH, pages 1 to 16 which document is thereby incorporated by reference.
Pads of fluffed cellulose pulp fibres absorb about 12 grams of water whereas a superabsorbent polymer may absorb up to one thousand (1,000) grams of water per gram of polymer.
However such a high performance is only reached with solutions in distilled aqueous water. Such superabsorbents lose rapidly their performances in solutions with a high ionic content.
However superabsorbent polymers are not used alone, but typically used in admixture with at least one another material with absorbing properties, in order to improve the absorbing profile. For example, superabsorbent polymer granules are mixed with wood pulp fluff in diapers.
Those superabsorbent polymers mainly used commercially are cross linked, partially neutralized poly(acrylic acid) or graft copolymers such as partially neutralized starch-g-poly(acrylic acid) and partially neutralized poly(vinyl alcohol)-g-poly(acrylic acid). Others well-known superabsorbent polymers are hydrolyzed starches-g-poly(acrylonitrile).
Intensive searches have been performed in order to improve the absorbency of known synthetic and semi-synthetic superabsorbents. Thus U.S. Pat. No. 4,935,022 describes absorbent articles which utilize a particular type of stiffened cellulose fibers and a particular type and form of polymeric gelling agent particles to enhance the absorbency characteristics of such articles. In these articles, the gelling agent material, combined in particulate form of a certain size with stiffened cellulose fiber material, is primarily placed in a lower fluid storage layer of the absorbent core of the article. Such a fluid storage lower layer of the absorbent core is placed underneath an upper, generally larger, fluid acquisition/distribution layer which also contains stiffened cellulose fibers and gelling agent particles of a certain size. The gelling particles have a mass median particle size ranging from about 400 to 1680 microns. The mentioned gelling agent is a substantially water-insoluble slightly, partially neutralised polymer selected from hydrolysed acrylonitrile grafted starch, polyacrylates, maleic anhydride-based copolymers and combinations of these polymers therefor.
U.S. Pat. No. 5,047,023 describes an absorbent article wherein the deposition region of its absorbent member comprises a storage zone and a acquisition zone having a lower average density and a lower average basis weight per unit area than the storage area. The acquisition zone is positioned toward the front of either the absorbent member or the absorbent article so that the acquisition zone may most effectively and efficiently rapidly acquire discharged liquids. The absorbent member comprises a mixture of a hydrophylic fibrous material and discrete particles of absorbent gelling material having a particle size distribution so as to enhance the absorbent capacity and acquisition rate of the absorbent member. The particles of the absorbent gelling material are selected to have a mass median particle size greater than or equal to about 400 microns with the amounts of very large and very small particles preferably kept below certain minimum concentrations. As suited absorbent gelling material particles are those already mentioned in U.S. Pat. No. 4,935,022. Mentioned as preferred absorbent gelling material are hydrolized acrylonitrile grafted starches, acrylic acid grafted starches, polyacrylates, maleic anhydride copolymers and combination thereof.
U.S. Pat. No. 5,061,259 describes absorbent structures and absorbent gelling agent compositions suitable for use in disposable absorbent articles. The absorbent structures comprise hydrophylic fiber material and nonfragile particles of polymeric gelling agent. The gelling agent particles incorporated into such structures are selected to have a mass median particle size ranging from about 400 to 700 microns, with no more than about 16% by weight of said particles having a particle size less than 200 microns and no more than about 16% by weight of said particles having a particle size greater than 1000 microns. The gelling agent particles are preferably nonfragile particles of hydrogel-forming polymeric gelling agent with a specific granulometry and comprise a specific amount of the grafted starches already mentioned in U.S. Pat. No. 5,047,023 and in U.S. Pat. No.4,935,022.
In spite of their advantages, the above mentioned synthetic or semi-synthetic superabsorbents, also called “super slurper”, exhibit major drawbacks.
Most of the synthetic superabsorbents are not biodegradable and semi-synthetic superabsorbents are generally only slightly biodegradable.
Moreover, due to their hardness and to their chemical nature, particulates of synthetic superabsorbents and particulates of semi-synthetic superabsorbents generate irritability of intimate body parts.
Allergic reactions to synthetic or semi-synthetic superabsorbents, occuring inter alia when granulates of synthetic superabsorbents come in contact with mucous membranes, are commonly reported.
Furthermore, semi-synthetic and synthetic superabsorbents are hygroscopic. This tendency to absorb moisture represents a major drawback. Particularly for applications wherein a long retention time of the absorbed fluid is required.
Finally and in having regard to new environmental regulations, there is an increasing need for biodegradable hygiene products like diapers. Such a need resulted over the past years in intensive searches for new biodegradable hypoallergenic and non-hygroscopic polymeric materials with a high absorbency and with good stability in a wide pH range.
SUMMARY
A first object of the present invention is a particulate absorbent, for the absorption of liquids, comprising particles of glass-like polysaccharides and/or of particles of glass-like polysaccharides occluding, in their internal structure, at least one surfactant. The glass-like polysaccharides are characterized in that their particles have a sp
Chevigny Stéphane
Huppé Serge
Maheux Marie-Elise
Quirion François
Bourque & Associates PA
Groupe Lysac Inc.
Peselev Elli
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