Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
2000-12-29
2003-07-22
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of silicon containing
C427S387000, C442S099000, C525S100000, C525S105000, C525S106000
Reexamination Certificate
active
06596402
ABSTRACT:
CROSS REFERENCE TO RELATED PATENTS AND PATENT APPLICATIONS
The subject matter of the present invention is related to copending and commonly assigned patent applications titled “Moisture-Induced Poly(Ethylene Oxide) Gel, Method Of Making Same And Articles Using Same”, and “Modified Poly(Ethylene Oxide), Method Of Making Same And Articles Using Same”, both of which were filed on May 26, 2000.
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to an absorbent, lubricious coating, and more particularly to an absorbent, lubricious coating which is water insoluble and is formed from a modified water soluble base polymer that crosslinks upon exposure to moisture.
(2) Description of the Related Art
Coatings that are water absorbent and lubricious are useful in medical applications such as coatings for surgical instruments, for in-dwelling biomaterials such as stents, screws and internal splints, and for tubing, catheters, wire guides and the like. Such coatings minimize the trauma of contact of the article with tissues and biological fluids. In particular, such coatings are particularly useful in fabrics and bandages that contact cuts and abrasions to provide coated fabrics and bandages that can absorb excess wound fluid without irritating exposed tissue.
Other products, such as disposable diapers, incontinence aids and feminine hygiene products are also great conveniences that depend upon characteristics of absorbency and biological inertness. However, these products are disposed of after a single use and most often ultimately are deposited into a landfill. If such products are made of non-biodegradable material, they persist in the landfill and can limit the later use of the landfill area while continuing to occupy space in the fill. Accordingly, it would be advantageous if the materials that comprise these disposable products were biodegradable.
Approaches that have been used in the past to provide materials that are lubricious and absorbent include the production of laminates having a porous non-stick surface backed by an absorbent pad, the synthesis of fibers and fabrics from absorbent, lubricious materials, and the formation of absorbent coatings on structurally durable, but non-absorbent materials. However, each type of structure has encountered its own particular problems. For example, laminates formed by bonding absorbent coatings to non-absorbent materials often delaminate or are impossible to bond together at all. Fibers and films produced from lubricious, absorbent compounds often have low strength and lack of integrity and durability.
Recent development efforts have provided materials that show promise for the types of uses described above and have improved processibility characteristics, and often, increased strength and durability. For example, in U.S. Pat. No. 6,054,523, Braun et al., describe materials that are formed from organopolysiloxanes containing groups that are capable of condensation, a condensation catalyst, an organopolysiloxane resin, a compound containing a basic nitrogen, and polyvinyl alcohol. The materials are reported to be suitable for use as hydrophobic coatings and for paints and sealing compositions.
Other workers have reported the production of graft copolymers having silane functional groups that permitted the initiation of cross-linking by exposure to moisture. Prejean (U.S. Pat. No. 5,389,728) described a melt-processible, moisture-curable graft copolymer that was the reaction product of ethylene, a 1-8 carbon alkyl acrylate or methacrylate, a glycidyl containing monomer such as glycidyl acrylate or methacrylate, onto which has been grafted N-tert-butylaminopropyl trimethoxysilane. The resulting copolymers were reported to be useful as adhesives and for wire and cable coatings, however, would not be expected that such materials would be either water-absorbent or lubricious when wet.
Furrer et al. (U.S. Pat. No. 5,112,919) reported a moisture-crosslinkable polymer that was produced by blending a thermoplastic base polymer, such as polyethylene, or a copolymer of ethylene, with 1-butene, 1-hexene, 1-octene, or the like; a solid carrier polymer, such as ethylene vinylacetate copolymer (EVA), containing a silane, such as vinyltrimethoxysilane; and a free-radical generator, such as an organic peroxide; and heating the mixture. The copolymers could then be cross-linked by reaction in the presence of water and a catalyst, such as dibutyltin dilaurate, or stannous octoate.
Keough (U.S. Pat. No. 4,593,071) reported moisture cross-linkable ethylene copolymers having pendant silane acryloxy groups. The resultant cross-lined polymers were reported to be especially resistant to moisture and to be useful for extruded coatings around wires and cables. The same group has reported water similar moisture curable polymers involving silanes in U.S. Pat. Nos. 5,047,476, 4,767,820, 4,753,993, 4,579,913, 4,575,535, 4,551,504, 4,526,930, 4,493,924, 4,489,029, 4,446,279, 4,440,907, 4,434,272, 4,408,011, 4,369,289, 4,353,997, 4,343,917, 4,328,323, and 4,291,136. Since the cured products of these formulations are reported to be useful for coverings for wire and cable, and for non-conductive coatings for electrical conductors, it would be expected that they are durable coatings for which properties such as water absorbency and biodegradability would be a disadvantage.
Water-swellable polymers have reportedly been produced by cross-linking water soluble polymers, such as poly(ethylene oxide). It is known that poly(alkylene oxides), such as poly(ethylene oxide), can be cross-linked through gamma irradiation. Depending upon the degree of irradiation and the degree of cross-linking, the properties of the cross-linked polymer can range from a water soluble material to a hard solid with no appreciable water absorbency. Materials that are substantially non-water soluble, but still absorbent can be made. However, the use of gamma rays requires expensive equipment and time consuming procedures due to safety concerns, and the degree of cross-linking that is obtained is often difficult to control.
Several references have reported the use of chemical cross-linking groups as a method of avoiding the dangers and costs associated with the use of ionizing radiation. Chu (U.S. Pat. No. 3,963,605) reported a water-swellable, cross-linked poly(alkylene oxide) that was produced by h mixture of poly(ethylene oxide) with acrylic acid and a free radical initiator such as acetyl peroxide in a hydrocarbon solvent such as hexane, heptane, or cyclohexane. Another alternative was reported in Canadian Pat. No. 756,190, and involved cross-linking through a di-vinyl monomer in the presence of a free radical catalyst. The use of other cross-linking agents, such as a diacrylate, or methyl-bis-acrylamide with a free radical inhibitor, has also been reported.
Lubricious coatings of cross-linked, hydrophilic polyurethane have been reported by Watson in U.S. Pat. No. 6,020,071. Another polyurethane coating is described by Tedeshchl et al., in EP 0992 252 A2, where a lubricious, drug-accommodating coating is described that is the product of a polyisocyanate; an amine donor, and/or hydroxyl donor; and an isocyanatosilane adduct having terminal isocyanate groups and an alkoxy silane. A water soluble polymer, such as poly(ethylene oxide), can optionally be present. Cross-linking causes a polyurethane or a polyurea network to form, depending upon whether the isocyanate reacts with the hydroxyl donors or the amine donors.
Despite these advances, there is still a need for a method to form a durable and plastic-like coating on an article where the coating is adherent to the article and yet has a high degree of water absorbency when contacted with an aqueous fluid. There is a particular need for such coatings that are biologically inert and nontoxic, are lubricious when moist, and can be formed under conditions that do not require irradiation or extreme temperatures. It is to such needs that the present invention is directed.
SUMMARY OF THE INVENTION
Briefly, therefore the present
Ambrosio Archel A.
Greene Sharon L.
Malik Sohail
Rouns Cameron G.
Soerens Dave
Dawson Robert
Keehan Christopher M.
Kimberly--Clark Worldwide, Inc.
Nelson Mullins Riley & Scarborough LLP
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