MXPA00011117A - Method for polymerizing contact lenses - Google Patents

Abstract

A method for photopolymerizing a monomer mixture toform a lens involves charging to a mold a monomer mixture including lens-forming monomers, and exposing the monomer mixture in the mold to a light source including light in the visible region of the spectrum. The method is useful for monomer mixtures that include a UV-absorbing compound and/or a tinting agent. Preferably, the monomer mixtures include a polymerization initiator including a phosphine oxide moiety.

Description

OD FOR POLYMERIZING CONTACT LENSES BACKGROUND OF THE INVENTION The present invention relates to a od for photopolymerizing a monomer mixture and forming a lens, wherein the monomer mixture can include a UV absorbing compound and a dye and is exposed to a light source that includes light in the visible region of the spectrum. Lenses such as contact lenses or intraocular lenses may include a UV absorbing agent in the lens to absorb light in the ultraviolet region of the spectrum, more specifically to absorb light in the region of approximately 200 to 400 nm and, especially, from about 290 to 400 nm. Representative UV absorbent materials for such lens applications are described in US Pat. No. 4..04.895 (Loshaek), 4.528..11 (Beard et al.) And 4,719,248 (Bambury et al.). Said lenses may also include a dye. The dye can be relatively rich in tone, so that it changes or at least enhances the color of the iris when the lens is placed on it. Alternatively, the dye may be relatively poor in tone, such that it does not change or enhance the color of the iris, but that it facilitates the manipulation of the ** £ - lens by the user; a representative "visibility dye" for contact lenses is described in US Pat. No. 4,997,897 (Melpolder). In general, said lenses are formed by free radical polymerization of a monomer mixture including the desired forming monomers, usually in the presence of heat (thermal polymerization) or a light source (fo-topolymerization). A particular od for producing contact lenses involves the thermal polymerization of the initial monomer mixture in tubes in a hot water bath to obtain rod-shaped articles, the rods of which are then cut into buttons, the buttons being turned into lenses. Contact; said ods for forming lenses that include a UV absorbing agent are illustrated in U.S. Pat. previously cited Nos. 4..04.895 (Loshaek) and 4.528..11 (Beard et al.). Other ods involve casting the lenses directly into molds, where the monomer mixture is loaded into the mold and polymerized by exposure to ultraviolet radiation. Among the photopolymerization processes, UV curing (ie exposure of the monomer mixture to radiation mainly in the ultraviolet region) of the monomer mixtures has proven to be very effective.

However, for lenses that include a UV absorbing agent, problems arise when attempting to cure the monomer mixtures, since this agent absorbs UV light, thus decreasing the amount of UV light available to effect the polymerization and resulting in an ineffective cure. uneven of the monomer mixture. It is also possible to perform photopolymerization using a light source that also includes light in the visible region of the spectrum, although light in this region is generally less effective in effecting the polymerization of conventional lens-forming monomer mixtures than curing by UV. U.S. Pat. No. 4,719,248 (Bambury) describes the success in the polymerization of contact lens compositions that include a UV absorbing agent by exposure of the monomer mixture to visible light. However, it has been found that the ods illustrated in the Bambury patent could not effectively polymerize contact lens monomer mixtures that included, in addition to the UV absorbing agent, a coloring agent. Accordingly, it would be desirable to have a od whereby lenses including both a UV absorbing agent and a coloring agent can be photopolymerized by free radical polymerization. The present invention facilitates said od and solves the problems mentioned above.

SUMMARY OF THE INVENTION The invention provides a od for photopolymerizing a monomer mixture and forming a lens by loading a monomer mixture in a mold including lens-forming monomers and exposing the monomer mixture in the mold to a light source includes light in the visible region of the spectrum. The od is useful for monomer mixtures that include a UV absorbing compound and a coloring agent. Preferably, the monomer mixtures include a polymerization initiator that includes a phosphine oxide moiety.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The monomer mixtures employed in the invention include conventional lens-forming monomers, UV-absorbing agents and coloring agents. Lens-forming monomers are monomers that are polymerizable by polymerization of free radicals, which generally include an activated unsaturated radical and, more preferably, an ethylenically unsaturated radical. (Such as used herein, the term "monomer" means compounds of relatively low molecular weight that are polymerizable by free radical polymerization, as well as compounds of higher molecular weight than those also referred to as "prepolymers", "macromonomers" and related terms). An especially preferred class of lens-forming monomers are those that form hydrogel copolymers. A hydrogel is a crosslinked polymer system that can absorb and retain water in a state of equilibrium. Accordingly, for hydrogels, the monomer mixture will typically include a hydrophilic monomer. Suitable hydrophilic monomers include: unsaturated carboxylic acids, such as methacrylic and acrylic acids; acrylic-substituted alcohols, such as 2-hydroxyethyl methacrylate and 2-hydroxyethyl acrylate; vinyl lactams, such as N-vinylpyrrolidone, and acrylamides, such as methacrylamide and N, N-dimethylacrylamide. Another preferred class of lens-forming monomers are those that form silicone hydrogel copolymers. Such systems include, in addition to a hydrophilic monomer, a silicone-containing monomer. A suitable class of monomers containing silicone includes bulky monomers and known monofunctional polysiloxane alkyl represented by Formula (I): wherein: X represents -COO-, -CONR4-, -OC0O- or -OCONR4-, where each R4 is H or lower alkyl, R3 represents hydrogen or methyl, h is 1 to 10 and each R2 independently represents a lower alkyl radical or halogenated alkyl, a phenyl radical or a radical of the formula -Si (R5) 3 wherein each R5 is independently a lower alkyl radical or a phenyl radical. Said bulky monomers specifically include methacryloxypropyltris (trimethylsilyloxy) silane, pentamethyldisiloxanylmethyl methacrylate, tris (trimethylsiloxy) methacryloxypropyl silane, methyl-di (tr? Methylsiloxy) methacryloxymethylsilane, carbamate 3- [tris (trimethylsiloxy) silylpropylvinyl and _- [tris (trimethylsiloxy) silyl] propylvinyl carbonate. Another suitable class is the multifunctional monomers containing ethylenically siloxane "capped at the end", especially the difunctional monomers represented by Formula (II): R. R. R «I. I. I -R'-YES-.0-S¡ -) - 0-Si-R'-A 'I I to I R8 R8 R8 (D) where: each A 'is independently an activated unsaturated group; each R 'is independently an alkylene group of 1 to 10 carbon atoms, where the carbon atoms may include ether, urethane or ureido linkages therebetween; each R8 is independently selected from monovalent hydrocarbon radicals or halogen-substituted monovalent hydrocarbon radicals having from 1 to 18 carbon atoms and which may include ether linkages therebetween, and a is an integer equal to or greater than 1. Preferably, each R8 is independently selected from alkyl groups, phenyl groups and fluoro-substituted alkyl groups. It is further noted that at least one R8 may be a fluoro-substituted alkyl group, such as that represented by the formula: -D '- (CF2) 0-M' where: D 'is an alkylene group of 1 to 10 atoms carbon, wherein said carbon atoms may include ether linkages therebetween; M 'is hydrogen, fluorine or an alkyl group, but preferably hydrogen, and s is an integer from 1 to 20, preferably from 1 to 6. With respect to A', the term "activated" is used to describe unsaturated groups including at least one substituent that facilitates the polymerization of free radicals, preferably an ethylenically unsaturated radical. Although a wide variety of such groups may be used, preferably A 'is an ester or amide of (meth) acrylic acid represented by the general formula: wherein X is preferably hydrogen or methyl and Y is -O- or -NH-. Examples of other suitable unsaturated activated groups include vinylcarbonates, vinylcarbamates, fumarates, fumaramides, maleates, acrylonitrile, vinyl ether and styryl. Specific examples of monomers of Formula (II) include the following: (Ilb) where: d, f, g and k vary between 0 and 250, preferably between 2 and 100; h is an integer from 1 to 20, preferably from 1 to 6, and M 'is hydrogen or fluorine. Another suitable class of silicone-containing monomers includes monomers of the Formulas (Illa) and (Illb): (Illa) E '(* D * A * D * G) a * D * A * D * E' or (Illb) E '(* D * G * D * A) to * D * G * D * E', where: D represents an alkyl diradical, an alkylcycloalkyl diradical, a cycloalkyl diradical, an aryl diradical or an alkylaryl diradical 6 to _0 carbon atoms; G represents an alkyl diradical, a cycloalkyl diradical, an alkylcycloalkyl diradical, an aryl diradical or an alkylaryl diradical of 1 to 40 carbon atoms and which may contain ether, thio or amine bonds in the main chain; * represents a urethane or ureide bond; a is at least 1; A represents a divalent polymer radical of formula: where: each Rz independently represents an alkyl or fluoro-substituted alkyl group of 1 to 10 carbon atoms which may contain ether linkages between the carbon atoms, m 'is at least 1 and p is a number that provides a remainder weight of 400 to 10,000; each E 'independently represents a polymerizable unsaturated organic radical represented by the formula: where: R23 is hydrogen or methyl; R24 is hydrogen, an alkyl radical of 1 to 6 carbon atoms or a radical -CO-Y-R26 / where Y is -O-, -S- or -NH-; R25 is a divalent alkylene radical of 1 to 10 carbon atoms; R26 is an alkyl radical of 1 to 12 carbon atoms; X represents -CO- or -OCO-; Z represents -O- or -NH-; Ar represents an aromatic radical of 6 to 30 carbon atoms; w is 0 to 6; x is O or l; and is O or l, and z is O or l. A specific urethane monomer is represented by the following: where m is at least 1 and is preferably 3 or 4, a is at least 1 and preferably is 1, p is a number that provides a remainder weight of 400 to 10,000 and is preferably at least 30, R27 is a diradical of a diisocyanate after removal of the isocyanate group, such as the diradical diisocyanate of isophorone and each E "is a group represented by: Other silicone-containing monomers include the silicone-containing monomers described in US Pat. No. 5,034,461, 5,610,252 and 5,496,871, the disclosures of which are incorporated herein by reference, other silicone-containing monomers are well known in the art.

In the case of hydrogels, either the silicone-containing monomer or the hydrophilic monomer can function as a cross-linking agent (a cross-linking agent being defined as a monomer having multiple polymerizable functionalities), or a separate cross-linker can be employed. Mixtures of monomers include a UV absorbing agent, defined as an agent which, being incorporated in the final lens, is capable of reducing at least 70% by light content in the region of 200 to 400 nm, more preferably at least 70% of the light in the region of 320 to 400 nm and at least 90% of the light in the region of 290 to 320 nm. The invention is suitable for monomer mixtures that include any conventional UV absorbing agent. A general class of such agents are non-polimepable absorbers, such as 2, 2-d? H? Drox -4,4-d-methox? Benzophenone and 2,2-d? H? Drox-4-methox Benzophenone Preferred are, however, the polymerizable UV-absorbing agents which include an activated n-saturated group reactive with the lens-forming monomers, whereby the UV-absorbing agent co-polymerizes with the lens-forming monomers. Representative polymerizable UV absorbent materials for such lens applications are described in US Pat.

Nos. 4,304,895 (Loshaek), 4,528,311 (Beard et al.), 4,716,234 (Dunks et al.), 4,719,248 (Bambury et al.), 3,159,646 (Milio-nis et al.) and 3,761,272 (Manneus et al.), the descriptions of which are incorporated herein by reference. Specific examples include: benzotriazole-containing monomers, such as 2- (2'-hydroxy-5'-methacrylamidophenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-5'-methacrylamidophenyl) -5 -methoxybenzotriazole, 2- (2'-hydroxy-5'-methacryloxypropyl-3'-t-butylphenyl) -5-chlorobenzo-triazole, 2- (2'-hydroxy-5'-methacryloxyethylphenyl) benzotria-zol and 2-methoxybenzotriazole; - (2 '-hydroxy-5' -methacryloxypropylphenyl) benzotria-zol, and the polymerizable benzophenones described in US Pat. No. 4,304,895.

The monomer mixtures may also include a coloring agent, defined as an agent which, by being incorporated in the final lens, imparts some degree of color to the lens. The invention is applicable to conventional coloring agents known in the art, including non-polymerizable agents or polymerizable agents that include an activated-unsaturated group that is reactive with the lens-forming monomers. A preferred example of the latter class is the compound 1,4-bis (4- (2-methacryloxyethyl) phenylamino) anthraquinone, a blue visibility coloring agent described in US Pat. N ° 4. 997,897. As mentioned, the photopolymerization of monomer mixtures to form lenses by UV curing has proven very effective; however, for lenses that include a UV absorbing agent, an ineffective or uneven cure occurs, since this agent absorbs UV light. The invention offers a method by which lenses including both a UV absorbing agent and a coloring agent can be effectively photopolymerized by polymerization of free radicals. More specifically, it was found that the use of an initiator including a phosphine oxide moiety allowed satisfactory curing of the monomer mixtures by photopolymerization to form lenses. Accordingly, it is preferred that the initial monomeric mixtures include an initiator containing phosphine oxide. The rest phosphine oxide can be represented by the formula: O II -P- Preferred initiators include the following phosphine oxide-containing radical: O O II II -c- p- where n is zero or one and, preferably, one. Representative compounds with this phosphine oxide-containing moiety are of the formula: where Ar and Ar 'are independently an optionally substituted aromatic radical and R is an optionally substituted alkyl or aromatic radical and n is zero or one and, preferably, one. As specific examples of such com- Positions containing phosphine oxide include: bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide ("TMBPPO"), bis (2,6-dimethoxybenzoyl) -2,4,4-tri-methylpentylphosphine oxide (" DMBA-PO "), 2, 4, 6-trimethyl-benzyldiphenylphosphine oxide and 2,4,6-trimethylbenzoyldi-phenylphosphine oxide (" MAPO "). The initiator systems marketed with these compounds include: Irgacure-819 ™ initiator, based on TMBPPO (Ciba Specialty Chemicals); Irgacure-1700 ™ initiator, which includes DMBAPO at approximately 25% by weight (Ciba Specialty Chemicals); Irgacure-1800 ™ initiator, which includes DMBAPO at approximately 25% by weight (Ciba Specialty Chemicals); MAPO (Ciba Specialty Chemicals), and Lucirin TPO ™ initiator, based on 2,4,6-trimethylbenzyldi-phenylphosphine oxide (BASF). In general, the monomer mixture is loaded into a mold and then subjected to light to effect curing of the monomer mixture in the mold. Various methods are known for curing a monomer mixture in the production of contact lenses, including rotary casting and static draining. Rotary emptying methods involve loading the monomer mixture into a mold and rotating the mold in a controlled manner while exposing the monomer mixture to light. Static emptying methods involve loading of the mixture of monomers between two sections of the mold, one section of the mold having a shape that produces the anterior surface of the lens and the other section of the mold having a shape that produces the posterior surface of the lens, and the curing of the mixture of monomers by exposure to light. Such methods are described in U.S. Pat. Nos. 3,408,429, 3,660,545, 4,113,224, 4,197,266 and 5,271,875.

For the present invention, any light source can be used as long as it provides light in the visible region of the spectrum and, especially, in the region of 400 to 500 nm. It is noted, however, that, in some cases, it may be desirable to filter light in the ultraviolet region of the spectrum, especially light in the region of 300 to 400 nm; In some cases, exposure to light in this region can result in a "deformation" of the lens or "curling" at the edges of the lens. Accordingly, although the light source need not provide light exclusively in the visible region of the spectrum, according to an especially preferred embodiment the monomer mixture is exposed to light predominantly in the visible region of the spectrum. This can be achieved by selecting an appropriate source of light relatively specific to visible light or by using a light source that provides a broad spectrum of light and filtering the UV radiation that falls on the monomeric mixture. The following examples illustrate various preferred embodiments. The following nomenclature is used in the description of experimental procedures: F2D2o - a polysiloxane diol fumarate-based prepolymer of Formula (lie) terminated terminally with t-butylamine (derivative of a polydimethylsiloxane diol, fumaryl and t-butylamma according to US Patent No. 5,420,324) and described in greater detail in Synthesis C below. ID2S4H - a prepolymer based on polyurethane capped with 2-metacplox? -et? Lo (isophorone dusocyanate derivative, diethylene glycol, a polydimethylsiloxanediol and 2-hydroxetane meta-platelet according to US Pat. No. 5,034,461) and described in more detail in Synthesis A below. ID3S4H - a prepolymer based on polyurethane capped with 2-metacplox? -et? Lo (dusocyanate derivative of isophorone, diethylene glycol, a polydimethylsiloxane diol and meta-plate 2-hydroxy ethanol according to US Pat. No. 5,034,461) and described in greater detail in Synthesis B below. TRIS - 3-metacplox? Prop? Ltr? S (trimethylsilo-xl) silane. DMA - N, N-d? Met? Lacplam? Da. IMVT-1,4-b? S (4- (2-metacr? Lox? Et? L) phenyl-ammo) anthrachone (Example 11 of US Patent No. 4,997,897), a coloring agent of Blue visibility. UV-2- (2-hydrox? -5-methacr? Lam? Dofe-n? L) -5-methox? Benzotrol azol agent (Example 4 of US Patent No. 4,719,248) . TXN-t-oxoanten-9-one. MDEA - N-metildietanolamma. Darocur-1173 ™ - a commercial initiator based on acetophenone (Ciba Specialty Chemical), based on 2-hydroxy-2-methy1phenylpropan-1 -one. Irgacure-184 ™ - (1-184) a commercial initiator based on acetophenone (Ciba Specialty Chemical), based on 1-h? Drox? C? Clohex? Lfe-n-l acetone. Irgacure-784 ™ - (1-784) a commercial initiator based on titanocene (Ciba Specialty Chemical) Irgacure-819 ™ - (1-819) a commercial initiator based on bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (Ciba Specialty Chemical). Irgacure-1700 ™ - (1-1700) a commercial initiator based on bis (2,6-dimethoxy-benzoyl) -2,4,4-trimethylpentylphosphine oxide (approximately 25% by weight) and the acetophenone-based initiator Darocur-1173 ™ (Ciba Specialty Chemical). Irgacure-1800 ™ - (1-1800) a commercial initiator based on bis (2,6-dimethoxy-benzoyl) -2,4,4-trimethylpentylphosphine oxide (approximately 25% by weight) and the acetophenone-based initiator Irgacure-184 ™ (Ciba Specialty Chemical). Synthesis A Preparation of a polyurethane polymer based on polydimethylsiloxane - (ID2S4H) A dry, 3-neck, 1000 ml round bottom flask was connected to a nitrogen inlet tube and a reflux condenser was attached. Then isophorone (16.916 g, 0.0761 mol), diethylene glycol (4.038 g, 0.0380 mol), dibutyltin dilaurate (0.383 g) and 140 ml of methylene chloride were added to the flask once and the contents were subjected at reflux. After 16 hours, the amount of isocyanate and was reduced to 47.0% by titration. Α, β-Bis (4-hydroxybutyl) polydimethylsiloxane (102.56 g, 0.02536 mol) was added to the flask. The reflux was continued for 33 hours and the amount of isocyanate was reduced to 14.1% of the original by titration. The contents were then cooled to room temperature. Then 2-hydroxyethyl methacrylate (2.2928 g) and 1.1 '-bi-2-phenol (0.0129 g) were added and the contents were stirred at room temperature until the isocyanate peak at 2.267 cm disappeared. " 1 of the IR spectrum of the product The solvent was then removed under reduced pressure to obtain the product Synthesis B Preparation of a polyurethane polymer based on polydimethylsiloxane - (ID3S4H) The procedure of Example 1 was followed, except for the fact that the molar ratios of the ingredients were varied, In particular, the amounts of the ingredients in the initial stage of synthesis were: isophorone diisocyanate (10.425 g, 0.04799 mol) and diethylene glycol (2.5469 g, 0.024 mol) and, in the following synthesis step, a, β-bis (4-hydroxybutyl) polydimethylsiloxane (74.22 g, 0.01799 mol) and 2-hydroxyethyl methacrylate (1.8376 g).

Synthesis C Preparation of a fumarate prepolymer based on polydimethylsiloxane thermically topped with t-butylamine (F2D20) A round bottom flask of 500 .1 and 3-wells was connected to a nitrogen inlet tube and a reflux condenser in series was attached to a tube of potassium hydroxide and a solution of sodium hydroxide. Fumaryl chloride (12.56 g, 0.082 mol), α, β-bis (4-hydroxybutyl) polydimethylsiloxane of Mn 1.595 (59.81 g, 0.0.75 mol) and 250 ml of anhydrous methylene chloride were added to the flask. . The contents were refluxed under a nitrogen purge. After 18 hours, it was seen that the OH groups had disappeared by analyzing an aliquot by high resolution NMR. The unreacted fumaryl chloride and the solvent were removed in vacuo. Then, 50 ml of methylene chloride was added and the mixture was cooled to 0-5 ° C. T-butylamine (11.67 g, 0.1595 mol) in 250 ml of methylene chloride was then added slowly to maintain a low temperature. The mixture was kept at room temperature by stirring overnight. The ammonium salt was filtered and the mixture was washed with aqueous sodium bicarbonate twice and then with water until neutral. The product was dried with magnesium sulfate and the methylene chloride was removed. It was dissolved again then this crude product (64.5 g) in 130 ml of methylene chloride and passed through a column of silica gel. The first 195 ml were collected and the column was then eluted with 65 ml of methylene chloride. The final 260 ml combined eluent was rotoevaporated and dried under vacuum at 80 ° C to obtain 62.3 g of product. The prepolymer was characterized by IR, by NMR and by size exclusion chromatography (TSC). IR (cm-1): 3325, 2962, 1727, 1644, 1541, 1456, 1412, 1365, 1297, 1257, 1222, 1159, 1010, 963 and 786; 200 MHz H-NMR (ppm) 0.00, 0.56 (t), 1.39 (s), 1.40 (m), 1.69 (m), 4.17 (t), 5.70 (broad), 6.77 (m); CET (with polystyrene standard) gave an Mn of 2593, an Mp of 3.887 and a polydispersity of 1.50. Preparation of monomer mixtures A first series of monomer mixtures, suitable for providing silicone hydrogel contact lenses, were prepared by mixing the following components: Mixture IA-F2D20 (20 parts by weight (pb)); TRIS (40 pep), DMA (40 pep), hexanol solvent (20 pep) and initiator Da-rocur-1173 (0.5 pep). Mixture IB - F2D20 (20 parts by weight (pep)), TRIS (40 pep), DMA (40 pep), solvent hexanol (20 pep) and UV Agent (0.5 pep).

Mixture 1C - F2D20 (20 parts by weight (pep)), TRIS (40 pep), DMA (40 pep), hexanol solvent (20 pep), UV Agent (0.5 pep) and IMVT (150 ppm). A second series of monomer mixtures, suitable for providing silicone hydrogel contact lenses, was prepared., mixing the following components: Mixture 2A - ID2S4H (50 parts by weight (pep)), TRIS (20 pep), DMA (30 pep), solvent hexanol (20 pep) and initiator Da-rocur-1173 (0.5 pep). Mixture 2B - ID2S4H (50 parts by weight (pep)), TRIS (20 pep), DMA (30 pep), solvent hexanol (20 pep) and UV Agent (0.5 pep). Mixture 2C - ID2S4H (50 parts by weight (pep)), TRIS (20 pep), DMA (30 pep), hexanol solvent (20 pep), UV agent (0.5 pep) and IMVT (150 ppm). General preparation of hydrogel films Mixtures of monomers were cured in films by placing the mixture between two silane-treated glass plates and exposing them to a light source for 1 hour. The cured films were removed from the plates and extracted with isopropanol and then heated in boiling water. The films were equilibrated in borate buffered saline prior to characterization. _ «_ & & _ ..

COMPARATIVE EXAMPLES 0.5% Darocur-1173 was added to Mixtures IB and 2B. These mixtures were then cured, together with the mixtures ÍA and 2A, under UV light (4000 μ) according to the procedure described above. Mixtures ÍA and 2A, which contained neither UV absorbing agent nor coloring agent, completely cured. However, as for Mixtures IB and 2B, which contained a UV absorbing agent, but no coloring agent, the mixtures became very viscous, but did not cure. Comparative Examples Mixtures IB, 1C, 2B and 2C were added with 0.2% by weight of TXN and 0.4% by weight of MDEA. These mixtures were then cured under visible light (approximately 16 mW) in a nitrogen atmosphere according to the procedure described above. Mixtures IB and 2B, which contained a UV absorbing agent, but no coloring agent, were cured, although the films were crimped. These results are consistent with the experiments described in US Pat. No. 4,719,248. However, as for Mixtures 1C and 2C, which contained both the UV absorbing agent and the coloring agent, the mixtures became very viscous, but not curable.

Comparative Examples To Mixes IB, 1C, 2B and 2C were added 0.2% by weight of camphor quinone and 0.4% by weight of MDEA. These mixtures were then cured under visible light (approximately 16 mW) in a nitrogen atmosphere according to the procedure described above. Mixtures IB and 2B, which contained a UV absorbing agent, but no coloring agent, were cured, although the films were crimped. However, as for Mixtures 1C and 2C, which contained both the UV absorbing agent and the coloring agent, the mixtures remained fluid. Comparative Examples To Mixtures 1C and 2C (containing both a UV absorbing agent and a coloring agent) Irgacure-784 initiator was added in amounts of 0.25, 0.5, 0.75 and 1.0% by weight . These mixtures were then exposed to visible light in a nitrogen atmosphere according to the procedure described above. The mixtures remained fluid. Examples 1 and 2 Irgacure-1700 initiator was added to Mixtures 1C and 2C (containing both a UV absorbing agent and a coloring agent) in amounts of 1.0, 2.0, 3.0 and 4.0 by cent in weight. Additionally, Irgacure-Initiator was added 1800 to Mixtures 1C and 2C in amounts of 1.0, 2.0, 3, 0 and 4.0 weight percent. These two initiator systems include about 25 weight percent of bis (2,6-d? Methox benzoyl) -2,4,4-methoxy-phosphorane oxide. This series of mixtures was then cured under visible light in a nitrogen atmosphere according to the procedure described above. Hydration and equilibration in borate buffered saline gave hydrogel films. The hydrogel films showed some curling at the edges of the films. Examples 3 and 4 Irgacure-819 initiator was added to Mixtures 1C and 2C (containing both the UV absorbing agent and the coloring agent) in amounts of 0.25, 0.5, 0.75 and 1.0 by cent in weight. This initiator system is based on bis (2, 4, 6-tpmet? Lbenzo? L) phenyl-phosphine oxide. This series of mixtures was then cured under visible light in a nitrogen atmosphere according to the procedure described above. The monomer mixtures were completely cured to form films. The films were slightly yellowish in appearance, but upon hydration and equilibration in borate-buffered saline, the hydrogel films appeared green. The hydrogel films showed some curling on the edges of the films. Examples 5 and 6 Irgacure-819 initiator was added to Mixtures 1C and 2C (containing both a UV absorbing agent and a coloring agent) at 0.75 weight percent. This initiator system is based on bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide. This series of mixtures was then cured under visible light as in Examples 3 and 4, except that a glass plate coated with a UV absorbing agent was put between the light source and the monomer mixture that had to be cured, such that this coated plate would be able to substantially filter all of the light underneath of 400 nm. The monomer mixtures were completely cured to form films. Upon hydration and equilibration in borate buffered saline, the hydrogel films exhibited no ripple. Example 7 A series of monomer mixtures prepared as in Examples 5 and 6 were used to empty contact lenses. The monomer mixtures were poured onto the molding surface of a first section of a plastic mold, provided with a shape that would provide an anterior contact lens surface, and a second section of a plastic mold was placed.

It had a molding surface provided with a shape that would provide a contact lens back surface on the first section of the mold, the monomer mixture being contained in the mold cavity formed between these two molding surfaces. This assembly was then subjected to a visible light source for 1 hour. The two sections of the mold were separated, the lenses were released from the mold section in isopropanol and then heated in boiling water. The lenses were equilibrated in borate buffered saline prior to characterization, resulting in hydrogel contact lenses having good optical quality. Example 8 The hydrogel films of Example 1 (based on Mixture 1C with 1.0 weight percent Irgacure-1700 initiator and based on Mixture 1C with 1.0 percent Irgacure-1800 initiator) were subjected to , whose films had a thickness of 180 microns, to UV-VIS absorption measurements. Both sets of films had a similar luminous transmittance. Wavelength (nm) Transmittance (% T) 400-800 92 200-400 2.7 320-400 (UVA) 6.5 320-290 (UVB) 0.4 290-200 (UVC) 0.2 Examples 9 to 18 Various initiators were added to the 1C Monomer Mixture and the hydrogel films were cured under a source of visible light and processed according to the general procedure described above. The mechanical study of the hydrogel films in buffered saline solution in an Instron instrument was carried out according to the modified ASTM D-1708 test procedure (tensile coefficient) and the ASTM D-1938 test procedure (tear strength). . The extractables of the cured films and the aqueous content of the hydrogel films were determined gravimetrically. The resuare given in the following table.

* Curing under a light source with UV filter (as in the procedure of Examples 5 and 6). Differential Scan Photocalorimetry (Photo CBD) Additionally, the curing of various monomer mixtures of Examples 9-18 was evaluated using differential scanning photocalorimetry. In a Dupont differential scanning calorimetry unit, the monomer mixture was placed in a sample pan at room temperature and polymerized under a nitrogen atmosphere by exposure to the light source. The exothermic profile was monitored and the following table gives the peak of time (time of the highest recorded exotherm) and the maximum heat flow (at the peak of time). For comparative purposes, 0.5% by weight of camphor quinoa ("CQ") and 0.5% by weight of MDEA were added to Mixture 1C (designated CM-1 in the table). The evaluation of Foto CBD did not give any recordable peak of time, as shown in the table.

* Curing under a light source with UV filter. Examples 19-27 As in Examples 9-18, several primers were added to the 2C Monomer Mixture and the hydrogel films were cured under a visible light source, processed and studied for mechanical properties. The CBD photo evaluation was also done. In the following tables, they give the resu _g ^ * Cured ba or a light source with UV filter.

* Curing under a light source with UV filter. Examples 28-31 Preparation of Mixture of Additional Monomers Mixtures of monomers, suitable for obtaining silicone hydrogel contact lenses, were prepared by mixing ID3S4H, TRIS and DMA. Additionally, IMVT was added at 150 ppm, 0.5Pw UV Agent was added and Irgacure-819 initiator at 0.5 pbw was added. These mixtures are called from here Monomeric Blend 3A. Monomeric mixtures, suitable for obtaining hydrogel contact lenses, were prepared from 2-hydroxyethyl methacrylate, N-vinylpyrrolidone, crosslinking monomers and 4-t-butyl-2-hydroxycyclohexyl methacrylate. Additionally, IMVT was added at 150 ppm, UV agent was added at 0.5 pbw and Irgacure-819 initiator at 0.5 pbw was added. These mixtures are called Monomeric Mixture 4A hereafter.

The mixtures were exposed to three different light sources, to cure and form films, using the general procedures described above: (1) a UV lamp (4,000 μW) that provided light mainly below 400, (2) ) a visible light source and (3) the same visible light source with a UV filter using a mount as in Examples 5 and 6. The attempted curing of Mixtures 3A and 4A under the (1) UV lamp It resulted in very curly films, which indicates an uneven cure. Mixtures 3A and 4A effectively cured using both the (2) visible light source and the (3) visible light source with a UV filter; the mechanical properties of these films, measured as in Example 9, appear in the following table.

Example 32 Mix 4A was used to empty contact lenses. The monomer mixture was placed on the molding surface of a first section of a plastic mold, provided in such a way as to provide a front contact lens surface and a second section of a plastic mold having a molding surface was placed. endowed in such a way as to provide a rear lens surface of touching the first section of the mold, the monomer mixture being contained in the mold cavity formed between these two molding surfaces. This assembly was then subjected to a visible light source, the UV radiation being filtered. In a test group, the two sections of the mold were immediately separated, the lenses were released from the mold section and finally equilibrated in borate buffered saline. In a second group of tests, the lenses were subjected to a thermal post-cure before separation of the sections of the mold and hydration. Both groups of tests, which resulted in hydrogel contact lenses, had good optical quality, with an aqueous content of 61.0% and 61.3%, respectively, a coefficient of 42 and 36 g / mm2, respectively. -te, and a tear strength of 2 g / mm for both tests. Many other modifications and variations of the present invention are possible to one skilled in the art in light of the teachings herein offered. It is understood, therefore, that, within the scope of the claims, the present invention can be practiced in ways other than those specifically described.

Claims (11)

Claims

1. A method for polymerizing a monomer mixture and forming a lens consisting of: loading into a mold a mixture of monomers including lens-forming monomers, a UV-absorbing compound, a coloring agent and a polymerization initiator including an oxide moiety of phosphine and exposing the monomer mixture in the mold to a light source that includes light in the visible region of the spectrum.

2. The method of claim 1, wherein the initiator includes a compound of the general formula: where Ar and Ar 'are independently an optionally substituted aromatic radical, R is an optionally substituted alkyl or aromatic radical and n is zero or one. & afe >

3. The method of claim 2, wherein n is one.

4. The method of claim 2, wherein the initiator includes a compound selected from the group consisting of: bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide and bis (2, 4,6-trime) oxide -ethylbenzoyl) phenylphosphine.

5. The method of claim 1, wherein the monomer mixture is exposed to light predominantly in the visible region of the spectrum.

6. The method of claim 5, wherein the UV light is filtered from the light source incident on the monomer mixture.

7. The method of claim 1, wherein the lens is a contact lens.

8. The method of claim 7, wherein the monomer mixture is polymerized in a mold cavity formed between a first section of the mold having a molding surface provided with a shape such as to provide a surface contact lens and a second section of the mold having a molding surface provided with a shape such as to provide a front contact lens surface.

9. The method of claim 7, wherein the lens is a hydrogel contact lens.

10. The method of claim 9, wherein the lens is a silicone hydrogel contact lens.

11. A method for polymerizing a monomer mixture and forming a lens consisting of: loading into a mold a monomer mixture including lens-forming monomers, a UV-absorbing compound and a polymerization initiator including a phosphine oxide moiety and exposing mixing in the mold to a light source that includes light in the visible region of the spectrum.