Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F291/00—Macromolecular compounds obtained by polymerising monomers on to macromolecular compounds according to more than one of the groups C08F251/00 - C08F289/00
  • C08F291/18—Macromolecular compounds obtained by polymerising monomers on to macromolecular compounds according to more than one of the groups C08F251/00 - C08F289/00 on to irradiated or oxidised macromolecules
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F265/00—Macromolecular compounds obtained by polymerising monomers on to polymers of unsaturated monocarboxylic acids or derivatives thereof as defined in group C08F20/00
  • C08F265/04—Macromolecular compounds obtained by polymerising monomers on to polymers of unsaturated monocarboxylic acids or derivatives thereof as defined in group C08F20/00 on to polymers of esters
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F271/00—Macromolecular compounds obtained by polymerising monomers on to polymers of nitrogen-containing monomers as defined in group C08F26/00
  • C08F271/02—Macromolecular compounds obtained by polymerising monomers on to polymers of nitrogen-containing monomers as defined in group C08F26/00 on to polymers of monomers containing heterocyclic nitrogen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F283/00—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F283/00—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G
  • C08F283/12—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G on to polysiloxanes
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
  • G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
  • G02B1/041—Lenses
  • G02B1/043—Contact lenses

Definitions

• the present invention relates to an interpenetrating polymer network (IPN) composition, especially a hydrophilic hydrogel composition for contact lens. More particularly, the present invention relates to polymerization of monomers in the presence of water soluble polymers as the IPN agents miscible with the monomer mixture using conventional crosslinkers or polymeric crosslinkers under ultraviolet and/Dr thermal curing condition.
• IPN interpenetrating polymer network
• IPN Interpenetrating polymer network
• an IPN is a whole unit structure formed from at least two distinct polymers.
• An IPN thereby has the physical and chemical properties of the constituent polymers, and thus combines the advantages of the polymers.
• hydrogels are often formed by copolymerization of monomers with the appropriate crosslinkers.
• the following patents disclose hydrogels formed by copolymerization.
• U.S. Pat. No. 5,665,840 entitled “Polymeric Networks from Water-Soluble Prepolymers,” to Pöhlmann et al., issued Sep. 9, 1997, discloses a water-soluble, crosslinkable prepolymer having monomeric structural units of a vinyl lactam, vinyl alcohol, alkanecarboxylic acid vinyl ester, vinylic crosslinking agent, and a vinylic photo initiator.
• the patent further discloses water-soluble crosslinkable prepolymer having a copolymer chain comprising 5 to 85% by weight of a vinyl lactam, for example, N-vinyl pyrrolidone.
• a vinyl lactam for example, N-vinyl pyrrolidone.
• a variety of N-vinyl lactams are disclosed according to a structural formula presented within. The most preferred vinyl lactam is N-vinyl-2-pyrrolidone.
• U.S. Pat. No. 4,430,458 entitled “Hydrogel-Forming Polymeric Materials,” to Tighe, et al., issued Feb.
• This patent claims a contact lens in the form of a hydrogel comprising a crosslinked polymeric material containing units derived either by simultaneous copolymerization and crosslinking or by co-polymerization and subsequent crosslinking of the following monomers: 20 to 40 mole percent of an amide of acrylic of methacrylic acid; 25 to 55 mole percent of an N-vinyl lactam of the N-vinyl pyrrolidone type; 5 to 20 mole percent of an hydroxy alkyl ester of acrylic or methacrylic acid; 1 to 10 mole percent of acrylic or methacrylic acid; and at least about 5 up to about 10 mole percent of a polymerizable hydrophobic vinyl monomer.
• U.S. Pat. No. 4,990,582 entitled “Fluorine-Containing Soft Contact Lens Hydrogels,” to Salamone, issued Feb. 5, 1991, discloses a soft contact lens material that exists as a hydrogel and is formed by a polymer containing a fluorinated monomer, a hydroxy alkyl ester of acrylic or methacrylic acid, and an N-vinyl lactam, According to the disclosure, an N-vinyl lactam is present from 5 to 80% by weight.
• N-vinyl lactam is critical in combination with the fluoromonomer and the hydroxy alkyl ester of acrylic or methacrylic acid, to obtain clear bulk copolymers without any haze or opacity.
• the preferred N-vinyl lactam is N-vinyl pyrrolidone in concentrations from 5 to 80% by weight and preferably from 40 to 60% by weight. In the claims, about 10 to about 50 parts by weight of N-vinyl lactam is present.
• U.S. Pat. No. 4,829,126 entitled “High Water-Absorptive Soft Contact Lens,” to Nakajima et al., issued May 9, 1989, discloses a highly water-absorptive soft contact lens made of a copolymer comprising 10 to 40 parts by weight of an acrylate or methacrylate polymer and 60 to 90 parts by weight of a hydrophilic monomer.
• methacrylate monomers having a hydrophilic group are used, such as the N-vinyl lactam, N-vinyl pyrrolidone.
• the patent discloses N-vinyl pyrrolidone as a preferred N-vinyl lactam monomer and phenylethyl methacrylate as a preferred hydrophobic acrylate.
• U.S. Pat. No. 4,440,919 entitled “Low N-Vinyl Lactam Content Based Biomedical Devices,” to Chromecek et al., issued Apr. 3, 1984, discloses N-vinyl lactam content copolymers that are crosslinked with resonance-free dye (alkine tertiary amine) cyclic compounds to obtain biomedical devices such as soft contact lenses.
• This patent also discloses the use of water-soluble diluents for use in the aforementioned polymer system to modify the physical properties of these properties. Such diluents are present, preferably, at not more than 30 weight percent. Diluents include low molecular weight, e.g., 500 to 10,000, linear poly (vinyl pyrrolidone).
• This patent discloses 2-hydroxyethyl methacrylate (“HEMA”)/N-vinyl pyrrolidone copolymer gels.
• HEMA 2-hydroxyethyl methacrylate
• Such gels are prepared by copolymerizing HEMA with N-vinyl pyrrolidone or graft-copolymerizing HEMA onto poly-N-vinyl pyrrolidone.
• a main point of this particular patent resides in the crosslinking agent used in combination with the methacrylate/N-vinyl lactam copolymerized mixture.
• U.S. Pat. No. 4,045,547 entitled “Fabrication of Soft Contact Lens and Composition Therefor,” to Le Bouef et al., issued Aug. 30, 1977, discloses a contact lens composition comprising from 67.2% to 79.3% HEMA; from 14.25% to 35% PVP; from 0.1% to 4.04% EDMA; from 0.1% to 2.5% MA; from 0.1% to 5.0% water; from 0% to 4% PPMHQ inhibitor; and from 50 to 250 PPM MEHQ inhibitor.
• the present invention relates to hydrogels comprising an interpenetrating polymer network (IPN).
• IPN of the present invention comprise at least one polymer, formed through polymerization of monomer, and at least one interpenetrating polymer network agent.
• the IPN agent comprises at least one polymer selected from the group of polymers comprising one or more monomeric units comprising at least one ⁇ N—C( ⁇ O)— group having an average molecular weight of from approximately 500 to approximately 300,000; polymers with one or more monomeric units comprising at least on N-oxide group having an average molecular weight of from approximately 500 to approximately 300,000; polymers comprising both ⁇ N—C( ⁇ O)— and N-oxide groups of (A) and (B); and mixtures thereof.
• additional materials are optionally added, such as, materials selected from the group consisting of monomers, polymer crosslinkers, polymerization initiators, ultraviolet absorbing material, colorant, antiseptic agents, and combinations thereof.
• the IPN hydrogels of preferred embodiments of the present invention have a water loss of less than approximately 5 weight percent after 5 minutes at approximately 75% humidity and approximately 24° C. Sample experiments demonstrating such water loss characteristics appear under the Example section of this disclosure wherein details of the experimental procedure also appear.
• the aforementioned at least one polymer, formed through polymerization of monomer comprises monomer selected from the group consisting of: 2-hydroxyethylmethacrylate, 2-hydroxyethylacrylate, methylmethacrylate; methylacrylamide; methacrylamide; N,N-dimethyl-diacetoneacrylamide; 2-phosphatoethylmethacrylate; di-, tri-, tetra-, penta-, . . .
• IPN agents are polymers with one or more monomeric units comprising at least on ⁇ N—C( ⁇ O)— group having an average molecular weight of from approximately 500 to approximately 300,000; polymers with one or more monomeric units comprising at least on N-oxide group having an average molecular weight of from approximately 500 to approximately 300,000; polymers comprising both ⁇ N—C( ⁇ O)— and N-oxide groups; and mixtures thereof. Therefore, for instance, polymers comprising N-vinyl pyrrolidone monomer wherein the pyrrolidone group appears on a less than one to one basis with respect to a polymer backbone subunit, e.g., vinyl, are within the scope of the present invention.
• the IPN hydrogel compositions of the present invention preferably comprise at least one IPN agent that is present from approximately 1% by dry weight to approximately 14% by dry weight and more preferably from 5% by dry weight to approximately 10% by dry weight.
• the average molecular weight of the IPN agent PVP the preferred average molecular weight is greater than 10,000.
• optional materials selected from the group consisting of monomers, polymer crosslinkers, polymerization initiators, ultraviolet absorbing material, colorant, antiseptic agents, and combinations thereof allow for modification of the general IPN hydrogel to meet specific needs and requirements, particularly for IPN-based contact lenses.
• Preferred embodiments of the hydrogel compositions of the present invention also comprise optional monomer such as at least one sulfoxide containing agent selected from the group consisting: sulfoxide containing methacrylates, sulfoxide containing acrylates, and combinations thereof.
• optional monomer such as at least one sulfoxide containing agent selected from the group consisting: sulfoxide containing methacrylates, sulfoxide containing acrylates, and combinations thereof.
• crosslinker is also optional and comprises at least one member selected from the group consisting of monomer and polymer.
• a molecular weight range from approximately 300 to approximately 1500 is preferred.
• the crosslinker is present from approximately 0.1% by dry weight to approximately 8% by dry weight and preferably from 0.5% by dry weight and approximately 4% by dry weight of the hydrogel.
• Preferred crosslinkers are polyethylene glycol dimethacrylate and ethylene glycol dimethacrylate, which are useful alone or in combination.
• polyethylene glycol dimethacrylate having a molecular weight of approximately 400 is mixable with that having a molecular weight of approximately 1000.
• material of varying molecular weight is combinable with crosslinker monomer(s).
• the hydrogel compositions of the present invention optionally include monomers other than the “principal monomer,” such as, but not limited to, at least one monomer selected from the group consisting of methyl methacrylate and N-vinyl lactams.
• the list of optional monomer includes the N-vinyl lactam, N-vinylpyrrolidone.
• the principal monomer is so called to define a particular group of monomers—at least one of which is always present in the inventive hydrogel.
• optional monomers are just that, optional. No limitation is made as to “principal” and weight percentage or parts, thus, IPN agent or optional monomer can exceed the weight percentage or parts of the principal monomer.
• a primary object of the present invention is water rentention.
• Preferred embodiments of the present invention use at least one interpenetrating network agent comprising an agent selected from the group consisting of polyvinylpyrrolidone, poly-2-ethyl-2-oxazoline, and poly(4-vinylpyridine N-oxide).
• preferred embodiments of the present invention using PVP and/or PEOX have shown water loss of less than 4%.
• Combinations of PVP, PEOX, and PVNO are within the scope of the present invention and are theoretically expected to produce results similar to the hydrogels presented in the examples contained within.
• a primary object of the present invention is to provide a biocompatible IPN-based hydrogel.
• a primary advantage of the present invention is formation of IPN-based hydrogels having superior water retention.
• a radiation such as, but not limited to, E-beam, ultraviolet and/or thermal, and microwave.
• Objects of the present invention are achieved through formation of hydrophilic hydrogel contact lens using, for instance, monomers such as unsaturated alkyl (meth)acrylate or its derivatives, preferably 2-hydroxyelhyl methacrylate (HEMA); optionally a vinyl containing comonomer(s), preferably methacrylic acid (MM), N-vinylpyrrolidone (NVP), or polyethylene(400) glycol (PEG 400) monomethyl ether monomethacrylate; crosslinking agents, preferably polyethylene glycol dimethacrylate in a molecular weight range from 400 to 1000; initiators, preferably 2,2′-azobisisobutyronitrile (AIBN), 2-hydroxy-2-methyl-1-phnyl-1-propanone (DAROCUR® 1173, E.
• monomers such as unsaturated alkyl (meth)acrylate or its derivatives, preferably 2-hydroxyelhyl methacrylate (HEMA); optionally a vinyl containing comonomer
• IPN agent preferably polyvinylpyrrolidone (PVP) or poly-2-ethyl-2-oxazoline (PEOX), wherein polymerization of monomers occurs through E-beam, ultraviolet, and/or thermal curing processes.
• PVP polyvinylpyrrolidone
• PEOX poly-2-ethyl-2-oxazoline
• the present invention relates to an IPN composition, especially a hydrophilic hydrogel composition for contact lenses. More particularly, the present invention relates to polymerization of a mixture of monomers and a synthesized non-ionic polymer as an IPN agent using a crosslinking agent or a mixture of crosslinking agents. After polymerization, via irradiation such as ultraviolet and/or thermal processing, the produced crosslinked polymer is hydrated to form a hydrogel having a low degree of surface friction, superior water retention, and a high degree of biodeposit resistance.
• the present invention also relates to the contact lens preparation including the polymerization process, prehydrated dry lens preparation, and corresponding hydration process.
• the principle monomers which can be used include, but are not limited to: 2-hydroxyethylmethacrylate (HEMA); 2-hydroxyethylacrylate (HEA); methylmethacrylate (MMA); methylacrylamide (MAA); methacrylamide; N,N-dimethyl-diacetoneacrylamide; 2-phosphatoethylmethacrylate; di-, tri-, tetra-, penta-, . . .
• HEMA 2-hydroxyethylmethacrylate
• the concentration of the principle monomer is typically in the range of 5% to 95% by weight, and preferably in the range of 20% to 85%, depending upon the desired properties of the resulting hydrogels.
• the additional highly hydrophilic comonomers useful in the present invention include, but are not limited to, acrylic acid, methacrylic acid, sulfoxide containing (meth)acrylate, N-vinylpyrrolidone, 2-acrylamido-2-methylpropanesulfonic acid and its salts, vinylsulfonic acid and its salts, styrenesulfonic acid and its salts, 3-methacryloyloxy propyl sulfonic acid and its salts, allylsulfonic acid, 2-methacryloyloxyethyltrimethylammonium salts, N,N,N-trimethylammonium salts, diallyl-dimethylammonium salts, polyethylene glycol (400) monomethyl ether monomethacrylate, gly
• the preferred additional comonomers are N-vinylpyrrolidone, sulfoxide containing (meth)acrylate, polyethylene glycol(400) monomethyl ether monomethacrylate, and glycerol monomethacrylate whose chemical structures are illustrated in Structure 2 to 5, respectively.
• n can be 1,2, and 3; R 1 can be either H or CH 3 ; and R 2 can be either CH 3 or C 2 H 5 .
• n is an integral indicating the number of repeating units for a specific molecular weight.
• n is 7.
• Sulfoxide containing methacrylates (SMA) and sulfoxide containing acrylate (SA) are a preferred constituent of the present invention.
• concentration of SMA and/or SA is in the range of approximately 5% to approximately 70% by weight, and preferably in the range of approximately 10% to approximately 50% by weight, depending on water content and other desired properties of the resulting hydrogels.
• the preferred additional comonomers in the present invention are methacrylic acid and acrylic acid whose general chemical structures are show in Structure 6.
• R can be either H or CH 3
• the concentration of additional comonomers in the present invention is typically in the range of 0% to 80% by weight, and preferably in the range of 0% to 60%, depending upon the type of comonomer used, the water content, and other desired properties of the resulting hydrogel.
• crosslinker is required.
• the crosslinkers are di-functional or multifunctional compounds that can incorporate themselves into the resulting polymer backbone during the polymerization process.
• examples of crosslinkers include, but are not limited to, ethyleneglycol di(meth)acrylate, triethyleneglycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, trimethylopropane tri(meth)acrylate, bisphenol A di(meth)acrylate, ethoxylate bisphenol A di(meth)acrylate, pentaerythritol tri-, and tetra(meth)acrylate, tetramethylene di(meth)acrylate, methylenebisacrylamide, methacryloxyethyl vinyl carbonate, triallylcyanurate, methacryloxyethyl vinyl urea, divinyl benzene, diallyl itaconate, allyl methacrylate, diallyl
• n is an integral indicating the number of repeating unit for a specific molecular weight. In the case of molecular weight of approximately 400 and approximately 1000, n is 5 and 19, respectively.
• the concentration of crosslinking agent is chosen according to the required degree of crosslinking and consequently it is determined not only by the amount of the crosslinker but by the type and ability to form the crosslinked polymer.
• the polymers of the present invention are preferentially prepared by radical polymerization utilizing the free radical initiators.
• E-beam, ultraviolet, microwave, and thermal process are used to initiate the polymerization.
• ultraviolet and/or thermal polymerization are used alone or in combination.
• the thermal initiators are preferably either azo- or peroxide families, including but not being limited to, 2,2′-azobisisobutyronitrile (AIBN), 1,1′-azodi (hexahydrobenzonitrile), 2,2′-azobis (2,4-dimethylpentanenitrile), 4,4′-azobis (4-cyanopentanoic acid), 2,2′-azobis (2-methylbutanenitrile), 2,2′-azobis(2,4-dimethyl-4-methoxylvaleronitrile), t-butyl peroctoate, benzoyl peroxide, lauroyl peroxide, methyl ethyl ketone peroxide, 2,4-olichlorobenzoyl peroxide, p-chlorobenzoyl peroxide, di-isopropyl peroxycarbonate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy) hexane, and the like.
• the thermal initiators are AIBN and 1,1-azodi (hexahydroben-zonitrile) in the present invention.
• the photoinitiators useful in the present invention include, but are not limited to, hydroxyalkylphenone such as 2-hydroxy-2-methyl-1-phenyl-1-propanono (DAROCUR® 1173), benzoin methyl ether (BME), and 2,2-dimethoxy-2-phenylacetophenone.
• the concentration of initiators used may be, for example, from 0.01% to 5% by weight, and is preferably from 0.2% to 1% by weight. If the quantity of initiators is too low, the resulting hydrogel may not be sufficiently resilient to spring back quickly or completely after folding and if the quantity is too high, a stiff but less elastic resulting hydrogel may be formed.
• UV ultraviolet
• benzophenone and benzotriazole familes of UV absorbers such as 2,2′-dihydroxy-4-methacryloyloxybenzophenone, 2,2′-dihydroxy-4,4′-dimethacryloyl′-oxybenzopherie, 2-hydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy) benzophenone, 2,2′-dihydroxy-4,4′-(3-bismethacrylo-yloxy-2-hydroxypropoxy) benzophenone, 1-, 4-, 5-, 6-, or 7-vinylbenzotriazole 4-, 5-, 6-, 7-, methacryloyloxybenzotriazole, 1-methacryloylbenzotriazole, 4-, 5-, 6-, or 7-methacryloylbenzotriazole, 4-, 5-, 6-, or 7-methacryloylbenzotriazole, 4-, 5-, 6-, or 7-methacryloylbenzotriazole, 4-, 5-, 6-
• handling colorant can also be employed in the hydrogel composition.
• Typical handling colorant is copper phthalocyanine blue in the present invention in a very small quantity that has been commonly used in the contact lens manufacture.
• the polymers used in the present invention as IPN agents are those that are homogeneously miscible with the monomer mixture at ambient temperature. These IPN agents are typically water soluble polymers including polyvinylpyrrolidone (PVP) having a molecular weight of 10,000 to 100,000 and preferably in the range of 30,000 to 80,000, as illustrated in Structure 8; poly-2-ethyl-2-oxazoline (PEOX) having a molecular weight of 10,000 to 1,000,000; and preferably in the range of 50,000 to 500,000, as shown in Structure 9; polyglycerol methacrylate as illustrated in Structure 10; and polyvinyl-pyrrolidone-iodine complex, as illustrated in Structure 11.
• PVP polyvinylpyrrolidone
• PEOX poly-2-ethyl-2-oxazoline
• a prominent feature of the IPN agents of the present invention is water solubility due to hydrophilic groups, such as ⁇ N—C( ⁇ O)— groups.
• polymers containing ⁇ N—C( ⁇ O)— groups include: polyvinylpyrrolidone (PVP); polyvinyloxazolidone; polyvinylmethyloxazolidone; polyacrylamide and N-substituted polyacrylamides, wherein R groups are independently selected from H and C1-C6 alkyl groups, e.g., methyl, ethyl, propyl, or isopropyl, or two R groups can form a 5 or 6 member ring structure; polymethacrylamide and N-substituted polymethacrylamides, wherein R groups are as described above; poly(N-acrylylglycinamide); poly(N-methacrylylglycinamide); poly(2-ethyl-2-oxazoline) (PEOX); and polyvinylurethan
• polymers have an amphiphilic character with polar groups conferring hydrophilic properties and apolar groups conferring hydrophobic properties.
• strength of any particular polar group, and combinations thereof, are variables considered within the scope of the present invention.
• Physicochemical properties of some of these polymers are given in “Water-Soluble Synthetic Polymers: Properties and Behavior,” Vol. 1, Philip Molyneux, CRC Press, 1983. These polymers are also useful in the present invention in partially hydrolyzed and/or crosslinked forms.
• PVP also known as povidone
• povidone is available in molecular weights ranging from approximately 1,000 to approximately 1,000,000. Due to its widespread use as a suspending or dispersing agent, in certain embodiments of the present invention, materials are suspended or dispersed in PVP to form a pre-mix. The same method of use applies to the aforementioned ⁇ N—C( ⁇ O)— group containing polymers.
• PVP-lodine also known as povidone-iodine (PVP-I 2 )
• PVP-I 2 povidone-iodine
• the same method of use applies to the aforementioned ⁇ N—C( ⁇ O)— group containing polymers wherein iodine is present.
• These particular polymers also have the potential for UV absorption. Under such circumstances, the concentration of UV initiator is adjustable to compensate for processes relying on UV initiated polymerization.
• N-oxides of heterocyclic compounds such as the N-oxides of pyridine, pyrrole, imidazole, pyrazole, pyrazine, pyrimidine, pyridazine, piperidine, pyrrolidone, azolidine, morpholine, and derivatives thereof are also useable alone or in combination with the aforementioned polymers.
• poly(4-vinylpyridine N-oxide) (PVNO) is useable alone or in combination with PVP and/or PVP-I 2 .
• n is an integral indicating the number of repeating unit of monomer for constructing the polymer.
• n is an integral indicating the number of repeating unit of monomer for constructing the polymer.
• n is an integral indicating the number of repeating unit of monomer for constructing the polymer.
• n is an integral indicating the number of repeating monomeric units for a specific molecular weight.
• the concentration of IPN agents used in the present invention is typically in the range of 1% to 14%, but preferably in the range of 5% to 10% depending upon the desired properties of the resulting hydrogels. It has been found that if a higher concentration is used, the resulting hydrogel generally has a higher water content but with a weaker mechanical strength. Surprisingly, when polyvinylpyrrolidone (PVP) is used as an IPN agent in a concentration greater than 5%, the resulting hydrogel exhibits a noticeable low degree of surface friction differing greatly from the surface friction characteristics of other hydrophilic hydrogels comprising conventional monomers made through a non-IPN process.
• PVP polyvinylpyrrolidone
• hydrophilic hydrogels prepared by the IPN process using PVP as an IPN agent show markedly lower water loss that is attributable to dehydration when compared to non-IPN processed analogues.
• the IPN agents such as PVP present in the hydrophilic hydrogel have a higher degree of water attraction ability that in turn prevents water evaporation from the hydrogel surface.
• the IPN processed hydrogel shows a lower protein and a lower lipid absorption rate than other non-IPN processed hydrogels when an artificial tear fluid is tested at 37° C. for 7 days.
• Polymers according to the invention can be produced by a variety of methods, such as bulk polymerization, solution polymerization, or possibly suspension polymerization in non-aqueous solution.
• Preferably bulk polymerization is used in the present invention. It is possible to polymerize purely by a thermal process, a photochemical process, or by combining both of these processes. It is also possible to perform polymerization using microwave or E-beam as the energy source.
• thermal process and photochemical process it is preferable first to proceed using an ultraviolet photochemical process followed by a thermal process.
• the polymerization temperature is maintained as a constant throughout the entire thermal process, or alternatively, increased in a stepwise or continuous manner.
• the polymeric material obtained by polymerization of the polymerizable compositions according to the present invention is manufacturable by first dispensing the composition directly in a mold having a desired form and then by performing the polymerization of the polymerizable composition in the mold.
• the surfaces of the mold should have the geometry which is the counter part of the resulting polymer.
• the conventional machining operation such as lathing can be used to produce the material of the desired geometry.
• the hydrated polymeric materials, i.e., hydrophilic hydrogels, in the present invention are obtainable by subjecting the finished polymer to hydration in deionized water, an aqueous salt solution, an aqueous surfactant solution, an alcoholic aqueous solution at ambient or elevated temperature for a sufficient period of time to reach a fully hydrated state, or combinations thereof.
• the hydrated lens samples (10 pieces) were lightly blotted using an optical cloth and immediately transferred to an analytical balance ( ⁇ 0.0001g in precision) and weighed. The lens samples were then placed in a thermal oven at 120° C. for 16 hours to dehydrate the lens samples, and finally weighed again on the same balance. The water content was calculated according to the equation below.
• Water Content(%) (wet weight of lens ⁇ dry weight of lens) ⁇ dry weight of lens
• the light transmittance of lens samples in saline was measured using a Beckman DU-64 spectrophotometer scanning from 400 nm to 800 nm at a speed of 750 nm/minute.
• the light transmittance of lens was expressed in %.
• This testing procedure was developed as an in vitro method to measure the amount of water loss from the hydrophilic hydrogen contact lens under controlled humidity and temperature (humidity was controlled at 75% ⁇ 2% and temperature was controlled at 24° C. ⁇ 1° C.).
• a given hydrated lens sample was first placed in UNISOL® 4 preservative free, pH balanced saline solution for 10 minutes for equilibration, then removed and gently blotted using an optical cloth to remove the surface water on the lens sample for about 3 seconds.
• the lens sample was then immediately placed on an analytical balance with a precision of ⁇ 0.0001 g and the initial weight was recorded and the value output through an automatic printer. Subsequently, the weight of the lens sample was recorded periodically at 30 seconds intervals for a period of 5 minutes. The initial weight and the final weight (5 minutes) were used to determine the percentage of water loss of the lens sample according to the following equation.
• Water Loss(%) [(final weight of lens sample ⁇ initial weight of lens sample) ⁇ 1] ⁇ % of Water Content of lens sample
• Table I lists absolute values of Water Loss, per the aforementioned equation, including a comparison of various lenses prepared in the examples that follow.
• the water loss data of each lens sample represents an average from at least 3 measured values.
• TABLE I Water Loss Lens Sample Major Components (%) Example 1 HEMA/sulfoxide containing 3.1 acrylate/PVP
• Example 2 HEMA/sulfoxide containing 3.0 acrylate/PVP
• Example 6 HEMA/MAA 6.0
• Example 9 HEMA/MAA 8.4 1 PROCLEAR ® Omafilcon 5.4 2 BENZ-G ® 5X Hioxifilcon 8.6 3 FOCUS ® Vifilcon 14.3 3 FOCUS DAILIES ® Neificon 11.0
• PROCLEAR® Biocompatibles Ltd., Middlesex, England
• index lens providing improved comfort for contact lens wearers who experience discomfort or symptoms related to dryness during wear.
• each dry lens sample was weighed using an analytical balance ( ⁇ 0.0001 g in precision).
• the weighed lens sample was hydrated, first in deionized water—repeated 2 times with agitation for about 30 minutes each time, then in a 15% isopropanol aqueous solution for about 30 minutes, and finally, two times in an aqueous saline solution with agitation for about 30 minutes each time.
• each lens sample was gently blotted using an optical cloth, placed in a thermal oven at 120° C. for 16 hours, and finally weighed again.
• the degree of polymerization expressed in % was calculated according to the equation below.
• reaction mixture was washed with deionized water (4 times with 1 L), saturated sodium bicarbonate solution (2 times with 100 mL), and again with deionized water (2 times with 1 L). After separation, the methylene chloride layer of the mixture was directly used in the subsequent oxidation outlined below.
• the extractant collected was mixed and stirred with 120 g of Bio-Rad anion exchange resin (OH form) for 6 hours, and filtered. The filtrate was then evaporated under reduce pressure at 50° C. to obtain a light brownish-yellow crude methyl-3-acryloyloxy propyl sulfoxide. The final purification of methyl 3-acryloyloxy propyl sulfoxide was conducted using a vacuum distillation technique to obtain a colorless oil product.
• the mixture was then filtered through a 1.0 ⁇ m polypropylene filter to remove any undissolved particles, followed by a vacuum degassing to remove oxygen and air bubbles present in the filtered mixture for 5 minutes at ambient temperature.
• the degassed solution was then dispensed to polypropylene female lens molds in an approximate amount of 30 ⁇ l to 60 ⁇ l for each mold. After dispensing, the female molds were capped slowly with corresponding polypropylene male lens molds.
• the assembly was then subject to UV polymerization using a UV light with an approximate energy level of 4 watts/inch for 4 to 5 minutes with no nitrogen blanket. After UV polymerization, the assembly was immediately transferred to a thermal oven for thermal curing at 105° C.
• the assembly was removed from the oven, and opened to separate the lens from the molds.
• the dry lens sample was hydrated, first in deionized water—repeated 2 times with agitation for about 30 minutes each time, then in a 15% isopropanol aqueous solution for about 30 minutes, and finally, two times in an aqueous saline solution with agitation for about 30 minutes each time.
• the hydrated lens so prepared shows a light transmittance greater than 98%, the degree of polymerization above 95% based on the gravimetric analysis of the dry lens and the re-dried hydrated lens, water content about 60%, and a low degree of surface friction that is especially tactilely noticeable.
• HEMA 99.5%) 62.35 methyl 3-(acryloyloxy) propyl sulfoxide 20
• PEG 400 dimethacrylate 1.25
• Methacrylic acid 0.5
• PVP approximatelyx. 38 K
• 1,1′-azodi(hexahydrobezonitrile) 0.15
• 2-hydroxy-4-acrylyloxyethoxy benzophenone 0.25 TOTAL 100
• HEMA 99.5%) 62 methyl 3-(acryloyloxy) propyl sulfoxide 20 PEG 400 dimethacrylate 1.25 PEG 1000 dimethacrylate 1 Methacrylic acid 0.5 PVP (approx. 38 K) 14 2-hydroxy-2-methyl-1-phenyl-1-propanon 0.5 2,2′-azobisisobutyzonitrile (AIBN) 0.5 2-hydroxy-4-acrylyloxyethoxy benzophenone 0.25 TOTAL 100
• HEMA (99.5%) 86.8 methacrylic acid 1.8 ethylene glycol dimethacrylate 0.4 PVP (approx. 38 K) 10 2-hydroxy-2-methyl-1-phenyl-1-propanon 0.25 2,2′-azobisisobutyzonitrile (AIBN) 0.5 2-hydroxy-4-acrylyloxyethoxy benzophenone 0.25 TOTAL 100
• HEMA 99.5%) 62 methacrylic acid 0.5 N-vinyl pyrrolidone 20 polyethylene glycol (400) dimethacrylate 1.25 polyethylene glycol (1000) dimethacrylate 1 PVP (approx. 38 K) 14 2-hydroxy-2-methyl-1-phenyl-1-propanon 0.5 2,2′-azobisisobutyzonitrile (AIBN) 0.5 2-hydroxy-4-acrylyloxyethoxy benzophenone 0.25 TOTAL 100
• Example 6 HEMA (99.5%) 98.15 methacrylic acid 0.5 ethylene glycol dimethacrylate 0.35 2-hydroxy-2-methyl-1-phenyl-1-propanon 0.25 2,2′-azobisisobutyzonitrile (AIBN) 0.5 2-hydroxy-4-acrylyloxyethoxy benzophenone 0.25 TOTAL 100
• the lens preparation was conducted in the same way as that described in Example 6, except that 10% of polyvinylpyrrolidone having a molecular weight of about 38,000 as an IPN agent was added to the monomer mix.
• HEMA 99.5%) 88.15 methacrylic acid 0.5 ethylene glycol dimethacrylate 0.35 PVP (approx. 38 K) 10 2-hydroxy-2-methyl-1-phenyl-1-propanon 0.25 2,2′-azobisisobutyzonitrile (AIBN) 0.5 2-hydroxy-4-acrylyloxyethoxy benzophenone 0.25 TOTAL 100
• HEMA (99.5%) 86.86 methacrylic acid 2 ethylene glycol dimethacrylate 0.14 PVP (approx. 38 K) 10 2-hydroxy-2-methyl-1-phenyl-1-propanon 0.25 2,2′-azobisisobutyzonitrile (AIBN) 0.5 2-hydroxy-4-acrylyloxyethoxy benzophenone 0.25 TOTAL 100
• the monomer mix was filtered, degassed, dispensed in a polypropylene mold having semi-spherical shape, and cured under a UV light with an approximate energy of 17 watts/inch 2 for 7 minutes with a nitrogen blanket for 6 minutes, followed by a thermal post curing at 70° C. for 7 to 9 hours.
• the semi-finished lens blank was finally lathed and hydrated in a manner similar to that described in Example 1.
• HEMA 99.5%) 96.36 methacrylic acid 2.04 ethylene glycol dimethacrylate 0.6 2,2′-azobisisobutyzonitriie (AIBN) 0.5 benzoin methyl ether (BME) 0.5 TOTAL 100

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• Optics & Photonics (AREA)
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• 1999
  • 1999-07-08 EP EP99933826A patent/EP1095076A4/fr not_active Withdrawn
  • 1999-07-08 DE DE1095076T patent/DE1095076T1/de active Pending
  • 1999-07-08 AU AU49801/99A patent/AU4980199A/en not_active Abandoned
  • 1999-07-08 WO PCT/US1999/015532 patent/WO2000002937A1/fr active Application Filing
• 2001
  • 2001-01-08 US US09/757,274 patent/US20010044482A1/en not_active Abandoned
• 2004
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