Coating processes – With post-treatment of coating or coating material – Plural film forming coatings wherein one coating contains a...
Reexamination Certificate
2003-03-14
2004-03-23
Dixon, Merrick (Department: 1774)
Coating processes
With post-treatment of coating or coating material
Plural film forming coatings wherein one coating contains a...
C427S355000, C427S337000
Reexamination Certificate
active
06709706
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method of providing a substrate, particularly a medical device or a part of such device intended for introduction in the human body, with a hydrophilic coating which becomes lubricous when contacted with an aqueous fluid. Substrates, particularly medical devices, with such hydrophilic coatings are also provided.
BACKGROUND OF THE RELATED TECHNOLOGY
It is generally known to provide substrates, for instance medical devices or parts of such devices, with a hydrophilic coating for the purpose of reducing the friction when the device is introduced in an aqueous environment, such as the human body. Such hydrophilic coatings have also been referred to as lubricous or “slippery” coatings.
Catheters and other medical devices used for introduction in blood vessels, urethra, body conduits and the like and guide wires used with such devices are examples of article which may be provided with hydrophilic coatings. Catheters for balloon angioplasty and biopsy are specific examples of such catheters.
Substrates and medical articles or devices having a hydrophilic coating and methods for providing such substrates and articles or devices with hydrophilic coatings have been described in an abundant number of references, examples of which are mentioned below.
U.S. Pat. No. 4,119,094 discloses a method of coating a substrate with a polyvinylpyrrolidone-polyurethane interpolymer. In the disclosed method, a polyisocyanate and a polyurethane in an organic solvent, such as methyl ethyl ketone, are applied to a substrate. The organic solvent is evaporated to yield a treated substrate. Polyvinylpyrrolidone in yet another organic solvent is then applied to the treated substrate. The solvent evaporated to provide the substrate with a hydrophilic coating.
U.S. Pat. No. 5,091,205 discloses a method of providing a substrate with a hydrophilic coating in which the substrate is first contacted with a polyisocyanate solution and then contacted with a poly(carboxylic acid) solution. Oven drying is described as being used to remove the organic solvents from these solutions. Methyl ethyl ketone is the preferred solvent for the polyisocyanates and dimethyl formamide is the preferred solvent for the poly(carboxylic acid). It is mentioned that the polyisocyanates can be dispersed in a solvent
on-solvent mixture to form an oil-in-water emulsion in which case, however, the reactive isocyanate groups need to be protected by suitable chemical groups.
EP Patent No. 0 106 004 B1 discloses a method of forming a hydrophilic coating on a substrate by applying a coating from an organic solvent solution of a polyisocyanate to form a coupling coating followed by application of an organic solvent solution of a hydrophilic copolymer made from monomers selected from vinyl pyrrolidone, vinyl methyl ether or vinyl pyridine and a monomer containing active hydrogen which will react with isocyanate to form a covalent bond between the coupling coating and the hydrophilic copolymer. Preferred organic solvents are described as being methyl ethyl ketone, chloroform and ethyl lactate.
EP Patent No. 0 166 998 B1 discloses a method for treating the surface of a medical instrument. The surface is treated with a solution of a polymer having a reactive functional group in an organic solvent followed by treatment with a water-soluble polymer selected from maleic anhydride polymers, cellulosic polymers, polyethylene oxide polymers, and water-soluble nylons or derivatives thereof to covalently bond the reactive functional group with the water-soluble polymer after which the treated substrate is optionally contacted with water. Certain ketones, aromatics, esters, ethers and halogenated hydrocarbons are described as being the organic solvent necessary for forming the solution.
U.S. Pat. No. 5,077,352 discloses a method in which a flexible, lubricous, organic polymeric coating is formed by applying a mixture of an isocyanate, a polyol and a poly(ethylene oxide) in a carrier liquid to a surface to be coated. The carrier liquid is removed and the mixture reacts to form a polyurethane coating with associated poly(ethylene oxide). Methylene chloride, chloroform, dichloroethane, acetonitrile, dichloroethylene, and methylene bromide are mentioned as suitable carrier liquids.
International Patent Applications Nos. PCT/EP92/00918, PCT/EP92/00919, and PCT/DK92/00132 disclose methods for providing different medical devices having a polyurethane surface with a coating of a hydrophilic poly(meth)acrylamide. Before application of the hydrophilic coating the substrate is treated with a compound having functional groups capable of reacting with the polyurethane and the poly(meth)acrylamide, respectively, typically a di or higher functionality isocyanate in an organic solvent.
A drawback of the methods according to the above-mentioned references is that the provision of the hydrophilic coating usually involves the use of organic solvents or toxic chemicals, for instance polyisocyanates, which can present environmental problems and/or health risks. In order to avoid the use of solvents some non-solvent methods have been developed.
EP Patent Application No. 92100787.8, Publication No. EP 0 496 305 A2, discloses a method for preparing a shaped medical article provided with a lubricous coating. A coating composition comprising a blend of polyurethane and polyvinylpyrrolidone is co-extruded with a substrate polymer to give a shaped article having thereon a layer of the coating composition which becomes lubricous when contacted with water.
U.S. Pat. No. 5,041,100 discloses a method for coating a substrate with a mixture of poly(ethylene oxide) and an aqueous dispersion of structural plastic material, e.g., polyurethane. As indicated in column 2, lines 15-21, the poly(ethylene oxide) is admixed without crosslinking in intimately dispersed relation with the structural plastic material to provide a hydrophilic component to the system, which may leach to the surface, or which may be entrapped adjacent the surface to provide a hydrophilic character thereto and reduce friction, particularly when hydrated.
The methods described in the above-mentioned references have the drawback that the interpolymer network physically attaching the hydrophilic polymer to the substrate often breaks down upon prolonged turbulent flow or soaking. Furthermore, the hydrophilic species can be washed away thereby rendering the article insufficiently lubricous.
Finally, International Patent Application No. PCT/DK91/00163 discloses a method of providing a medical instrument with a hydrophilic, low-friction coating, which method comprises the steps of forming an inner layer from an aqueous polymer emulsion and an outer layer from an aqueous solution of a water-soluble hydrophilic polymer and curing the two layers simultaneously following application of the outer layer by heating to a temperature of above 100° C.
The above method eliminates the use of organic solvents and results in a coating which is strongly attached to the substrate. However, the use of curing temperatures above 100° C. limits the use of the method, because many devices, for instance poly(ethylene terephthalate) (PET) balloon catheters cannot resist such temperatures.
SUMMARY OF THE INVENTION
The present invention is directed to a method of providing a substrate, particularly a medical device or a part of such device intended for introduction in the human body, with a hydrophilic coating becoming lubricous when contacted with an aqueous fluid, which method among others makes it possible to coat devices which are sensitive to high processing temperatures, such as (PET) balloon catheters. The hydrophilic polymer becomes covalently bonded to the polymers of an underlying coating to form a unitary hydrophilic coating.
In one aspect of the present invention a unitary hydrophilic coating is formed from multiple aqueous dispersions of emulsions of polymers. A first coating composition is formed from an aqueous dispersion or emulsion of a polymer having organic acid functional groups and a fir
Nunez George
Welch Eric
Zhong Sheng-ping
Dixon Merrick
Kenyon & Kenyon
Sci-Med Life Systems, Inc.
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