Coating processes – Medical or dental purpose product; parts; subcombinations;... – Implantable permanent prosthesis
Reexamination Certificate
2002-05-09
2004-12-28
Michener, Jennifer Kolb (Department: 1762)
Coating processes
Medical or dental purpose product; parts; subcombinations;...
Implantable permanent prosthesis
C427S002100, C427S002310, C427S487000, C427S508000, C427S553000, C427S558000, C427S162000, C427S164000, C427S399000, C427S301000, C427S407100, C427S414000
Reexamination Certificate
active
06835410
ABSTRACT:
This application claims under 35 U.S.C. §119(a)-(d) or §365(b) of European Patent Application No. 01810503.1 filed May 21, 2001.
The present invention relates to a process for coating articles, wherein the coating comprises a polymer having desirable characteristics regarding adherence to the substrate, durability, softness, hydrophilicity, lubricity, wettability, biocompatibility and permeability. More particular, the present invention relates to a process for coating an article, such as a biomedical material or article, especially a contact lens including an extended-wear contact lens, wherein the coating is composed of at least two individual hydrophilic polymer components. One of those hydrophilic components comprises polymer chains which are covalently bound to the substrate, whereas the second hydrophilic polymer is not covalently bound neither to the surface of the substrate nor to the polymer chains, but is being entrapped with said polymer chains.
Processes for preparing hydrophilic polymeric coatings on an “inert” hydrophobic substrate have been disclosed in the prior art. For example, WO 99/57581 discloses to first of all providing the article surface with covalently bound photoinitiator molecules, coating the modified surface with a layer of a polymerizable macromonomer and then subjecting it to a heat or radiation treatment whereby the macromonomer is graft polymerized thus forming the novel article surface. The covalent binding of the photoinitiator molecules to the article surface is created by first subjecting the article surface to a plasma treatment thereby providing the surface with functional groups, and then reacting said functional groups with co-reactive groups of a functional photoinitiator.
Surprisingly, it now has been found that articles, particularly biomedical devices such as contact lenses, with an even improved wettability, water-retention ability and biocompatibility are obtained by first of all providing the bulk material surface with covalently bound photoinitiator molecules, followed by grafting a hydrophilic ethylenically unsaturated macromonomer from the bulk material surface in the presence of a biocompatible hydrophilic polymer being devoid of polymerizable ethylenically unsaturated groups and thereby entrapping said biocompatible hydrophilic polymer within the polymer matrix formed by the polymerization of the macromonomer.
By this process, the macromonomer forms “bottle-brush” type tethered “hairy” chains on the bulk material surface having entangled a biocompatible hydrophilic polymer thereby forming a kind of semi-interpenetrating network (s-IPN) with the polymer chains of the macro-monomer.
The present invention therefore in one aspect relates to a process for coating a material surface comprising the steps of:
(a) providing an inorganic or organic bulk material having covalently bound to its surface initiator moieties for radical polymerization;
(b) graft polymerizing a hydrophilic ethylenically unsaturated macromonomer from the bulk material surface in the presence of a biocompatible hydrophilic polymer being devoid of polymerizable ethylenically unsaturated groups and thereby entrapping said hydrophilic polymer within the polymer matrix formed by the polymerization of the macromonomer.
Suitable bulk materials to be coated according to the invention are, for example, quartz, ceramics, glasses, silicate minerals, silica gels, metals, metal oxides, carbon materials such as graphite or glassy carbon, natural or synthetic organic polymers, or laminates, composites or blends of said materials, in particular natural or synthetic organic polymers or modified biopolymers which are known in large number. Some examples of polymers are polyaddition and polycondensation polymers (polyurethanes, epoxy resins, polyethers, polyesters, polyamides and polyimides); vinyl polymers (polyacrylates, polymethacrylates, polyacrylamides, polymethacrylamides, polystyrene, polyethylene and halogenated derivatives thereof, polyvinyl acetate and polyacrylonitrile); or elastomers (silicones, polybutadiene and polyisoprene).
A preferred group of materials to be coated are those being conventionally used for the manufacture of biomedical devices, e.g. contact lenses, in particular contact lenses for extended wear, which are not hydrophilic per se. Such materials are known to the skilled artisan and may comprise for example polysiloxanes, perfluoroalkyl polyethers, fluorinated poly(meth)acrylates or equivalent fluorinated polymers derived e.g. from other polymerizable carboxylic acids, polyalkyl (meth)acrylates or equivalent alkylester polymers derived from other polymerizable carboxylic acids, or fluorinated polyolefines, such as fluorinated ethylene or propylene, for example tetrafluoroethylene, preferably in combination with specific dioxols, such as perfluoro-2,2-dimethyl-1,3-dioxol. Examples of suitable bulk materials are e.g. lotrafilcon A, neofocon, pasifocon, telefocon, silafocon, fluorsilfocon, paflufocon, elastofilcon, fluorofocon or teflon AF materials, such as teflon AF 1600 or teflon AF 2400 which are copolymers of about 63 to 73 mol % of perfluoro-2,2-dimethyl-1,3-dioxol and about 37 to 27 mol % of tetrafluoroethylene, or of about 80 to 90 mol % of perfluoro-2,2-dimethyl-1,3-dioxol and about 20 to 10 mol % of tetrafluoroethylene.
Another group of preferred materials to be coated are amphiphilic segmented copolymers comprising at least one hydrophobic segment and at least one hydrophilic segment, which are linked through a bond or a bridge member. Examples are silicone hydrogels, for example those disclosed in PCT applications WO 96/31792 and WO 97/49740.
A particular preferred group of materials to be coated comprises organic polymers selected from polyacrylates, polymethacrylates, polyacrylamides, poly(N,N-dimethylacrylamides), polymethacrylamides, polyvinyl acetates, polysiloxanes, perfluoroalkyl polyethers, fluorinated polyacrylates or -methacrylates and amphiphilic segmented copolymers comprising at least one hydrophobic segment, for example a polysiloxane or perfluoroalkyl polyether segment or a mixed polysiloxane/perfluoroalkyl polyether segment, and at least one hydrophilic segment, for example a polyoxazoline, poly(2-hydroxyethylmethacrylate), polyacrylamide, poly(N,N-dimethylacrylamide), polyvinylpyrrolidone polyacrylic or polymethacrylic acid segment or a copolymeric mixture of two or more of the underlying monomers.
The material to be coated may also be any blood-contacting material conventionally used for the manufacture of renal dialysis membranes, blood storage bags, pacemaker leads or vascular grafts. For example, the material to be modified on its surface may be a polyurethane, polydimethylsiloxafle, polytetrafluoroethylene, polyvinylchioride, DACRON® (a long-chain polyester made from ethylene glycol and tereophthalic acid), SILATIC® (a flexible inert silicone rubber), or a composite made therefrom.
The form of the material to be coated may vary within wide limits. Examples are particles, granules, capsules, fibres, tubes, films or membranes, preferably moldings of all kinds such as ophthalmic moldings, for example intraocular lenses, artificial cornea or in particular contact lenses.
The bonding of the photoinitiator moieties according to step (a) may be accomplished
(i) according to the methods described in WO 99/57581, where the surface of the bulk material is first of all subjected to a plasma treatment thereby introducing reactive groups at the surface of the surface, followed by reaction of said reactive groups with an initiator moiety bearing co-reactive functional groups, or
(ii) by reaction of certain hetero-bifunctional compounds at the surface of the bulk material said compounds having a first highly reactive functional group, which is able to react with the “inert” bulk material surface, and a second functional group for further covalent attachment of the initiator moieties.
Said hetero-bifunctional compound is, for example, a compound of formula
or −N
3
(2b)
wherein R
29
is C
1
-C
4
-alkyl, C
1
-C
4
-
Chabrecek Peter
Leukel Jörg
Lohmann Dieter
Gorman Robert
Kolb Michener Jennifer
Meece R. Scott
Novartis AG
Zhou Jian
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