Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-08-29
2004-04-20
Shosho, Callie (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S916000, C524S517000, C525S207000, C525S221000
Reexamination Certificate
active
06723781
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to articles created using blends of polymers and other ingredients, and to a process for preparing the same. The articles serve as a hydrogel for applying various substances to a substrate. The substance can be a personal care compound, a biologically active compound, an active ingredient, an absorptive material, etc. The substrates can be living organisms, or inanimate objects. The hydrogels after being formed, can be dried to facilitate ease of handling. The dried hydrogels can be rewet as by an open wound, blood, etc. without substantial loss of properties.
2. Background Art
The earliest cataplasms were probably called poultices. A poultice is a medicated mass (often clay, herbal component, and a carrier such as water) spread on cloth and applied to the skin, often for sores or other lesions. Later, various gels and viscosity modifiers were added to cataplasms. Typically and preferably, a cataplasm has direct contact with skin or the substrate to be treated. As prepared commercially in a multiple cataplasm package, a cataplasm often has a backing on one side, which provides physical strength and a durable exposed surface during use on the substrate, and a release layer on the other side, which is removed before application to the substrate.
Transdermal delivery systems have been developed for various pharmaceutical applications. They generally transfer a medicine through the skin rather than to the skin. The active ingredients in commercial transdermal delivery systems are usually limited to a single chemical compound or a family of compounds. These systems are typically more expensive than oral medication and comprise an impermeable backing layer, a reservoir, a metering layer, and an adhesive layer. The system is usually protected by a release layer.
SUMMARY OF INVENTION
Hydrogels containing various substances or compounds such as personal care compounds, pharmaceuticals, etc., are described. The hydrogel contains significant amounts of water therein and is a blend of a crosslinked polymer and a high molecular weight essentially linear polymer. Noncovalent crosslinks, such as ionic crosslinks in the presence of cure rate modifiers, permit the hydrogel to be formed into a suitable end product before being cured.
The hydrogel compositions of the present invention can be dehydrated as in the form of a film, sheet, membrane, layer, etc., through conventional methods either in-situ or after being applied to a backing. Upon re-wetting, the film, sheet, membrane, layer, etc., reverts to a gel with physical characteristics substantially similar to the pre-dried hydrogel composition. Advantages of the dried hydrogel composition include direct application to a wound, mucous areas of the body, and the like. Other advantages include easier packaging, stabilization, less costly shipping, and customer convenience.
DETAILED DESCRIPTION OF THE INVENTION
From a compositional aspect, the hydrogel is a blend of at least two polymers one of which is a crosslinked polymer derived from one or more olefinically unsaturated polymerizable carboxylic monomers and optionally one or more comonomers. The other polymer is a high molecular weight substantially linear polymer derived from one or more olefinically unsaturated polymerizable carboxylic acid monomers. The hydrogel also contains a neutralizing agent; desirably a noncovalent crosslinking agent; and a cure rate modifier; and is generally located on a backing with a release compound or liner covering the hydrogel. The hydrogel is typically applied to a substrate such as human skin and contains therein a substance such as a personal care compound, a pharmaceutical, an active ingredient, or the like; The hydrogel is typically located on a substrate.
In some embodiments, the hydrogel removes a compound from the substrate by binding an absorptive substance to the substrate. That is, the hydrogel and its active ingredient act as absorbents of an impurity or irritants. An example of this would be the removal of undesired oil or other components from the skin. The hydrogel offers a new way to deliver or remove some compounds (those not before applied with cataplasms) to/from various substrates with improved performance attributes.
The hydrogel comprises any natural or synthetic polymer that is highly swollen by water. In the cataplasm application the hydrogel and its backing desirably remain a coherent mass, i.e. it doesn't fracture during application, removal, or use and can be discarded as a single unit of waste. It is generally desired that none of the hydrogel, other than the delivered substance, remain on the substrate after use. The backing can be any material convenient to the particular application. It is generally only present for ease of handling and integrity purposes, although it can facilitate application and solvent retention. Wovens, nonwovens, and films such as plastic can be used as backings. Natural or synthetic products can also be used. The release liner can be any suitable material known to the art or to the literature and generally is a plastic which optionally contains a release agent thereon such as a silicone.
Desirably the hydrogel is crosslinked or otherwise linked together as an integral material (e.g. a polymer and/or a noncontinuous hydrogel can be connected together via interentanglement of the chains, crystalline crosslinks, ionic crosslinks, hydrogen bonds, etc). For the purposes of this specification, integral will mean some connection, either temporary or permanent, that allows the hydrogel to function as a solid at typical storage and use temperatures of the particular substance. Function will imply that the hydrogel does not unduly flow, fracture, or fragment during use, but understandably does not imply tremendous physical integrity, which is not generally required. The preferred polymers forming the hydrogel will be gel-like particles that have the capacity to increase their volume by swelling in water by a factor from about 10 to about 1000 or 10,000. Preferably, they swell from about 10, 20, 30, or 40 times to about 500 or 1000 times their original volume.
Polyurethanes may also be used in the hydrogel. These may be thermoplastic or elastomeric polyurethanes. They may be hydrophobic, hydrophilic or amphiphilic depending on the active ingredients or other additives to be incorporated into the hydrogel. Polyurethanes and their precursors are well known to the art. It is preferred that the polyurethanes only be an additive to the hydrogel and that they be appropriately functionalized or processed to be uniformly dispersed in the hydrogel.
According to the present invention, an olefinically unsaturated polymerizable carboxylic monomer is utilized. Such monomers are described in detail and set forth in U.S. Pat. No. 5,468,797, as well as prior U.S. Pat. Nos. 5,373,044, and 5,288,814 thereof, which are hereby fully incorporated by reference with regard to all aspects thereof. As set forth in the '797 patent, the monomer contains at least one activated C═C group as well as a carboxyl or anhyride group. Such polymers can be homopolymers of an unsaturated, polymerizable carboxylic monomer containing from 3 to 34 carbon atoms, and preferably from 3 to 6 carbon atoms such as an acrylic acid, methacrylic acid, maleic acid, itaconic acid, maleic anhydride, and the like. The carboxyl containing polymers, before crosslinking, have molecular weights greater than about 500 to as high as several million, usually greater than about 10,000 to 900,000 or more.
Copolymers of the polymerizable carboxylic monomers can be made utilizing monomers having a total of from 3 to about 40 and desirably from 3 to about 34 carbon atoms such as acrylate esters, acrylamides, olefins, vinyl esters, vinyl ethers, vinyl amides, amines or styrenics. The amount of repeat units derived from such comonomers is generally from about 0.001 to about 30 percent and desirably from about 0.01 to about 20 percent by weight of the copolymer.
Typical materials are
Frate Dean M.
Guo Jian-Hwa
Budak, Shunk & Farine Co. LPA
Dunlap Thoburn T.
Noveon IP Holdings Corp.
Shosho Callie
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