JPS6262324B2 - - Google Patents

Description

[Detailed description of the invention]

Recently, hard contact lens materials with improved oxygen permeability have been developed. One such material is illustrated in US Pat. No. 3,808,178, which describes contact lenses made from copolymers of polysiloxanyl acrylates and alkyl acrylates. Other such hard contact lens materials have also been developed. Sometimes it is difficult to obtain good dimensional stability in contact lenses made from siloxanyl alkyl ester vinyl monomers. Dimensional stability is an important property of rigid contact lenses, affecting both accurate vision correction and user comfort. It is known that dimensional changes in hard lenses can occur rapidly and immediately after cutting and finishing treatments or after long periods of time. Such changes can be of various types. Changes to the base curve or other curves of a contact lens whose change is uniform are known as "steepening" or "flattening" depending on the direction of the change. Non-uniform changes in lens dimensions are called "warp." Dimensional changes in the molds described above may occur as a result of one or more factors including internal stress or strain relief experienced during the manufacturing or finishing process or loss of material within the lens. The prior art has developed methods for dealing with internal stress and strain problems by performing careful annealing of lens blanks. Gas permeable contact lenses made from copolymers or high molecular weight polymers containing siloxanyl alkyl ester vinyl monomers have encountered dimensional stability difficulties. These difficulties are a result of difficulties in the reactivity ratios between the various monomers used in the materials and chain transfer reactions during the polymerization process. Contact lenses made from such materials can contain a significant portion of unreacted monomer.
This may provide dimensional stability when these monomers are separated from the material. These monomers may separate from the lens shortly after its manufacture or after an extended period of time. If these monomers were to leach during use, they would have toxicological significance. Now, it has been found that the dimensional stability of a polymeric material useful as a contact lens and containing a siloxanyl alkyl ester vinyl monomer can be greatly increased. These materials can be polymerized by any known method. Such polymerization reactions usually contain up to 4% by weight of residual unreacted monomer, such as typically 1-2%;
Leaving monomer mixtures, oligomers and other low molecular weight materials, these residues are largely
It will leach or ooze out during normal contact lens use, and any residue is described herein as unreacted monomer. Second
In the process, the polymerized material is treated with high energy radiation to increase the degree of polymerization of unreacted monomers, thereby increasing the dimensional stability of the material. The object of the present invention is to provide a contact lens material which has good dimensional stability and which can be formed into contact lens blanks and contact lenses.
The objective is to provide blanks and lenses with good dimensional stability and a minimum amount of unreacted monomer by conventional methods. Another object of the present invention is to provide a method for improving the dimensional stability of contact lens polymeric materials made at least in part from siloxanyl alkyl ester vinyl monomers. Yet another object of the invention is to treat polymeric materials useful for forming contact lenses, blanks or lenses formed from said materials with high energy radiation to improve dimensional stability. , consists in using high-energy radiation. According to the present invention, one method is provided for improving the dimensional stability of polymeric materials useful in forming contact lenses. The method consists of selecting a polymeric material polymerized from a siloxanyl alkyl ester vinyl monomer and at least one comonomer and containing a small amount of unreacted monomer therein. The polymeric material is then exposed to high energy radiation to reduce the amount of unreacted monomer and increase dimensional stability in a second or post polymerization step. The resulting material shows good dimensional stability. Preferably the radiation is in the form of gamma rays from 0.005 to 10
Absorbed dose of megarad, more preferably 1~
The absorbed dose is 4 megarads. Preferably, the material is irradiated where it can be irradiated in the form of a lens blank having a thickness up to 1/4 inch, albeit with a greater thickness. If desired, the material in bulk form or the final lens can be irradiated. It is a feature of the invention that high-energy radiation is applied to stabilize the material, which may be in the form of a contact lens or blank. Since a high degree of polymerization is obtained when a second polymerization step is used, not only is the dimensional stability improved;
Physical properties are often improved. Contact lens materials are typically polymerized into rod shapes, then cut to approximate shape to form lens blanks or lens buttons, and then machined to final lens dimensions. The method of the invention can be carried out at any stage of contact lens manufacturing. For example, rods, buttons or lenses may be exposed to radiation. The lens or button, which is typically 3/16 inch when irradiated, allows the polymerization reaction to occur in order to increase the degree of polymerization and without reducing the desired physical properties of the material.
It can be successfully irradiated to proceed to near 100% reaction. High energy radiation useful in the present invention generally has from about 15 to about 0.003 million electron volts (Me.v.) per particle or quantum. Any known high energy radiation source can be used, for example as described in the table below.

[Table] If gamma rays are used, the absorbed dose is preferably in the range of 0.005 to 10 megarads, more preferably in the range of 1 to 4 megarads. When using X-rays, the absorbed dose is within the range given for gamma rays, while when using electron beam radiation, the absorbed dose is preferably within the range from 0.005 to 1 megarad. The time of exposure to radiation can vary significantly depending on the particular material and type of radiation. For example, gamma ray irradiation takes place over a period of time, such as 24 hours, whereas electron beam irradiation can be obtained instantaneously. Preferably, the polymeric material to be irradiated undergoes a conventional polymerization reaction,
polymerized, for example by free radical reaction, to less than 4% by weight of residual or unreacted monomer;
Typically, 1-2% by weight of unreacted monomer remains prior to the irradiation step. The irradiation step is preferably carried out to a sufficient degree of polymerization to substantially reduce or eliminate the total amount of unreacted monomer present in the polymer. Although radiation is known to polymerize various polymeric materials, the use of radiation as a second step in the polymerization of contact lenses or contact lens materials is not known. Curing by graft polymerization of thin coating formulations for wire insulation and modification of polymeric surfaces is known in other fields. Twenty years ago, it was shown that the effect of gamma radiation on polymethyl methacrylate and polyethyl methacrylate was significantly dependent on the amount of residual monomer present in the polymer sample, Journal of Polymer Science 44 , 295.
(1960). It has also been found that X-ray irradiation of polymethyl methacrylate orthopedic cements results in a significant reduction in residual methyl methacrylate content (American Chemical Society Organic Coatings and Plastics, 37 ). [2] 205 and 210, 1977). In all cases, the irradiation treatment is preferably carried out at room temperature in an inert atmosphere. Gamma radiation can be obtained from common commercial sources such as cobalt-60 and cesium-137. X-ray radiation with energies greater than those of polymeric materials can be easily obtained. The polymeric materials useful in the present invention are preferably highly oxygen permeable contact lens compositions, such as those published in 1974 entitled "Oxygen Permeable Contact Lens Compositions, Processes and Articles of Manufacture Thereof".
United States Patent Published on April 30th
No. 3,808,178, the entire patent is herein incorporated by reference. The above patent describes a composition particularly adapted for the manufacture of contact lenses and having increased permeability, consisting essentially of (a) about 10 to 60 parts by weight of the structural formula (wherein X and Y are selected from the group consisting of _C1 - _C5 alkyl groups, phenyl groups and Z groups, and Z is A is selected from the group consisting of _C1 - _C5 alkyl groups and phenyl groups, R is selected from the group consisting of methyl groups and hydrogen, m is an integer from 1 to 5, and n is an integer from 1 to 3)
Polysiloxanyl alkyl ester represented by
and (b) about 40 to 90 parts by weight of a solid copolymer of a comonomer consisting of an ester of a _C1 to _C20 monohydric alkanol with an acid selected from the group consisting of acrylic acid and methacrylic acid. Contains. Preferred lens materials for treatment with high energy radiation in accordance with the present invention are generally those described by Edward J.
U.S. Patent filed February 15, 1978, filed February 15, 1978, and assigned to the same assignee as the present invention, entitled "Improved Silicone-Containing Hard Contact Lens Materials" invented by John Ellis and Joseph C. Salamon This is the mold material described in No. 878163.
The specification of that application is herein incorporated by reference. In general, preferred formulations are (a)
30-80% by weight of the following general formula [wherein R ₁ is selected from the group consisting of hydrogen and methyl, a is an integer from 1 to 3, and b and c are 0
is an integer of ~2, d is an integer of 0 to 1, and A
is selected from the group consisting of methyl and phenyl groups, and R ₃ and R ₄ represent a c to d cyclic ring or represent either a methyl or phenyl group.
(b) 5 to 60% by weight of itaconic acid mono- or diester; (c) 1 to 60% by weight of _C1 to _C20 monohydric or polyhydric alkanols or phenols, consisting essentially of acrylic acid and methacrylic acid. (d) 0.1 to 10% by weight of a cross-linking agent; and (e) 1 to 20% by weight of a hydrophilic agent which imparts hydrophilicity to the surface of the contact lens material of the invention. consisting essentially of a polymer formed from monomers;
A highly transparent, oxygen permeable, hard, machine cuttable, dimensionally stable hydrophilic contact lens material. Generally, copolymers useful in the present invention range from 10 to
It may be formed from 90% by weight siloxanyl alkyl ester monomer or mixture thereof and 10-90% by weight itaconic ester or 10-90% by weight acrylic or methacrylic ester. Mixtures of itaconate and acrylic or methacrylate esters totaling 10 to 90% by weight are generally preferred because they exhibit a broader balance of lens properties. Other necessary ingredients known in the art, such as initiators, crosslinkers, wetting agents, colorants, etc., may be added to the known polymeric materials. The general formula for useful polymeric materials is: Siloxanyl alkyl ester monomers useful in the present invention preferably have the formula: where R ₁ is selected from hydrogen or a methyl group, a is an integer of 1 to 3, b and c are integers of 0 to 2,
A is selected from methyl or phenyl group, R ₃
and R ₄ represent a cyclic ring c to d or represent either a methyl or phenyl group, and d
is an integer between 0 and 1. Representative siloxanyl alkyl ester monomers that can be utilized in the present invention include the following. Methacryloyloxymethylpentamethyldisiloxane Methacryloyloxypropyltris(trimethylsilyl)siloxane Methacryloyloxymethylheptamethylcyclotetrasiloxane Methacryloyloxypropylheptamethylcyclotetrasiloxane Itaconic acid esters useful in the present invention have the following structure: X and X are the same or different and are hydrogen, methyl or phenyl. Representative mono- and diitaconate esters are methyl itaconate, dimethyl itaconate, phenyl itaconate, diphenyl itaconate, methylphenyl itaconate. Fracture strength imparting material is _C1
~ _C20 Esters of monohydric or polyhydric alkanols, or phenols, with acids selected from the group consisting of acrylic acid and methacrylic acid. Such esters are methyl methacrylate, methyl phenyl acrylate, phenyl methacrylate, cyclohexyl methacrylate. Examples of cross-linking agents include, but are not limited to, acrylic acid, methacrylic acid, acrylamide, methacrylamide, and polyfunctional derivatives of multi-vinyl substituted benzenes, such as, but not limited to, the following compounds: Ethylene glycol diacrylate or dimethacrylate Diethylene glycol diacrylate or dimethacrylate Tetraethylene glycol diacrylate or dimethacrylate Polyethylene glycol diacrylate or dimethacrylate Trimethylolpropane triacrylate or trimethacrylate Bisphenol A diacrylate or dimethacrylate Ethoxylated bisphenol A diacrylate Acrylate or dimethacrylate Tetramethylene diacrylate or dimethacrylate Methylenebisacrylamide or methacrylamide Dimethylenebisacrylamide or methacrylamide N·N'-dihydroxyethylenebisacrylamide or methacrylamide Hexamethylenebisacrylamide or methacrylamide Decamethylenebisacrylamide or methacrylamide Divinylbenzene Wettable surfaces are provided by the inclusion of hydrophilic neutral monomers, hydrophilic cationic monomers, hydrophilic anionic monomers, and mixtures thereof. These groups of compounds are hydrophilic acrylates and methacrylates, acrylamide, methacrylamide, and vinyl lactams. Typical hydrophilic neutral monomers include 2-hydroxyethyl acrylate or methacrylate, N-vinylpyrrolidone, acrylamide, methacrylamide, glyceryl acrylate or methacrylate, 2-hydroxypropyl acrylate or methacrylate, polyethylene glycol monoacrylate or methacrylate. is included.
The cationic monomers can either be initially in their charged form or are substantially converted to their charged form after formation of the contact lens. These groups of compounds are derived from basic or cationic acrylate, methacrylate, acrylamide, methacrylamide, vinylpyridine, vinylimidazole, and diallyldialkylammonium polymerizable groups. Representative examples of such monomers are as follows. N.N'-dimethylaminoethyl acrylate and methacrylate 2-methacryloyloxyethyl trimethylammonium chloride and methyl sulfate 2-.4-. and 2-methyl-5-vinylpyridine 2-.4-. and 2-methyl-5 -Vinylpyridinium chloride and methyl sulfate N-(3-methacrylamidopropyl)-N・N
-dimethylamine N-(3-methacrylamidopropyl)-N・
N.N-trimethylammonium chloride 1-vinyl- and 2-methyl-1-vinylimidazole 1-vinyl- and 2-methyl-1-vinylimidazolium chloride and methyl sulfate N-(3-acrylamido-3-methylbutyl) -N/N-dimethylamine N-(3-acrylamido-3-methylbutyl)-N/N/N-trimethylammonium chloride N-(3-methacryloyloxy-2-hydroxypropyl)-N/N/N-trimethylammonium Chloride Diallyldimethylammonium chloride and methyl sulfate The anionic monomers are either initially in their neutral form or are substantially converted to their anionic form. These compounds include polymerizable monomers containing carboxy, sulfonate, and phosphonate or phosphonate groups. Representative examples of such monomers include acrylic acid, methacrylic acid, sodium acrylate, sodium methacrylate, vinyl sulfonic acid, sodium vinyl sulfonate, p-
Styrenesulfonic acid, sodium p-styrenesulfonate, 2-methacryloyloxyethylsulfonic acid, 3-methacryloyloxy-2-hydroxypropylsulfonic acid, 2-acrylamide-
Examples include 2-methylpropanesulfonic acid, allylsulfonic acid, and 2-phosphatoethyl methacrylate. The copolymers presented in this invention are prepared by free radical polymerization by incorporation of free radical initiators. The initiator is selected from those commonly used to polymerize vinyl type monomers, typical initiators include 2,2'-azo-bis-isobutyronitrile, 4,4'- Examples include az-bis-(4-cyanopentanoic acid), t-butyl peroctoate, benzoyl peroxide, lauroyl peroxide, methyl ethyl ketone peroxide, and diisopropyl peroxy carbonate. Free radical initiators are normally used in amounts of 0.01 to 2% by weight of the total composition. The materials of the invention can be directly polymerized in a suitable mold to form contact lenses. All of the materials are thermosetting, so different fabrication methods can be used. It is preferred to polymerize into sheets or rod stocks, from which contact lenses can be machined. For example polymethyl methacrylate (PMMA)
It is preferred to apply conventional approaches when forming contact lenses for use.
In this approach, the above-described formulations are polymerized directly into sheets or rods, and the contact lens blank is cut into buttons, discs, or other preliminary shapes, and then the lens surface and final lens shape are cut. Machined to obtain. The resulting button polymer stock has the optical properties necessary to make an aberration-free, oxygen-permeable, rigid contact lens in accordance with the present invention. Of course, referring to the polysiloxanyl alkyl ester vinyl monomer in the polymers of the invention, two or more monomers can be used instead of just one monomer, and this is explained above. The same applies to each of the monomers listed in . Therefore, one or two itaconic esters can be used instead of just one ester if desired. The following examples are included to illustrate the invention and are not intended to limit it. Example: A hard, oxygen-permeable contact lens formulation containing dimethyl itaconate (DMI),
2,2′-Azobisiso from a copolymer mixture of methyl methacrylate (MMA), methacryloyloxypropyltris(trimethylsilyl)siloxane (TRIS), methacrylic acid (MA), and tetraethylene glycol dimethacrylate (TEGDM). Prepared using butyronitrile (AIBN) free radical initiator. The formulation ingredients (indicated in parts by weight in the table) are thoroughly mixed, transferred to a test tube, capped, degassed and
It was then filled with nitrogen. The tubes were then placed in a 40°C water bath and allowed to polymerize for 2 days. The tube was placed in an oven at 60° C. for an additional 2 days, after which the solid rod was removed from the tube. The rod was then conditioned under reduced pressure at 100° C. for about 18 hours and then slowly cooled to room temperature to create a stress-free material. The conditioned rods were then machined into discs measuring 3/16" to 1/2". This disc has the usual shape for hard polymethyl methacrylate lens blanks. The finished discs were then subjected to gamma irradiation in a Gamma Cell 200 instrument (manufactured by Atomic Energy of Canada Limited of Ottawa, Canada). The cell is
Delivering a central dose rate of 2.12× ¹⁰⁵ rad/ ^cm3 /hr
It contained 1230 curies of cobalt-60 in the form of 20 ray bundles. The disk was irradiated under nitrogen atmosphere, with a total exposure time between 1×10 ⁶ rad (1MR) and 5×10 ⁶ (5MR).
adjusted to deliver the total dose absorbed into the material. Both irradiated and unirradiated discs were subjected to distilled water extraction at 75°C for 6 hours. 100% extract with distilled water
ml and UV absorbance measurements were performed at three wavelengths. The data in the table can be extracted (remains) from lens blanks by gamma ray irradiation.
It clearly shows that the content of material, ie unreacted monomers, is significantly reduced.

TABLE EXAMPLE The rigid, oxygen-permeable lens formulations shown in the table were prepared using the experimental techniques detailed in the example. Lens blanks were irradiated with gamma rays under a nitrogen atmosphere to various total emission doses. Contact lenses were made from these discs using common techniques in the manufacture of rigid contact lenses. The test lenses were standardized to the following prescription: Base Curve Radius 7.95 mm Diopters -7.0 Diopters Center Thickness 0.12 mm Diameter 12 mm The base curve of each lens was marked after manufacture and then checked again after soaking in distilled water for 2 days. The variation in base curve radius as a function of irradiation dose is shown in the table and illustrates the effectiveness of gamma irradiation as a means of imparting dimensional stability to contact lenses.

TABLE: * Average of several test lenses ** Within acceptable range Examples The rigid, oxygen permeable lens formulations shown in the table were prepared using the experimental procedures detailed in the examples. Lens blanks were irradiated with gamma rays under a nitrogen atmosphere to various total emission doses. Compressive strength at yield point (yield) was measured using a TINIUS-OLSEN testing machine under the following conditions. Sample size: 3/16″ x 1/2″ Temperature: 73〓 Test speed: 0.05in/min A large number of measurements were taken, and the average values are shown in the table. It is clear from these data that the compressive strength of the lens material is significantly improved by irradiation treatment at total levels as low as 2 megarads.

TABLE EXAMPLE The rigid, oxygen permeable lens formulations shown in the Table were prepared using the techniques detailed in the Examples. The lens blank was irradiated with an electron beam and gamma rays under a nitrogen atmosphere. Standard transmissive samples in the form of plano contact lenses were machined from the above samples to the following formulations. Base Curve Radius 8.00 mm Diopter Plano Center Thickness 0.20 mm Diameter 12.0 mm Permeability was measured in an instrument designed according to ATMD 1434-66. In this instrument one side of the sample is exposed to pure oxygen at a pressure of 1 atmosphere (gauge). Oxygen passing through the lens sample is allowed to expand against atmospheric pressure in a capillary tube plugged with a drop of mercury to the other side of the sample. The rate of movement of the mercury column is easily converted to permeated volume per unit time. The system was calibrated based on measurements made on materials of known permeability. A large number of measurements were carried out and the average values are shown in the table. This table shows that effective _O2 permeability values are retained after irradiation.

Table Although specific examples of the invention have been described, many variations are possible. Such variations include the use of mixtures of monomers within the proportions of each component required. For example, two or more siloxanyl alkyl ester monomers can be used in place of a single monomer, such as the monomer component of the systems described above. Similarly, two or more crosslinkers can be used. Conventional additives to lenses, such as colorants, can also be used within the range normal for such materials. In all cases, high-energy radiation
Substantially complete polymerization of the polymeric material, thus improving dimensional stability and 1/2% by weight of unreacted monomers
It is used to act as a second or post-polymerization step to reduce The contact lens of the present invention and the material from which the lens is made are 38 to 500 cm ³ mm/cm ² /sec.cmHg×
Oxygen permeability in the range of 10 ^-10 and 100 to 125 ASTM
d-785 R scale Rockwell hardness,
and dimethyl itaconate, methyl methacrylate,
Preferably, it is formed from a polymer consisting of methacryloyloxypropyltris(trimethylsilyl)siloxane, methacrylic acid and tetraethylene glycol dimethacrylate. Such lenses can be used on the user's eyes for long periods of time.

Claims (1)

[Scope of Claims] 1 Consisting of a siloxanyl alkyl ester vinyl monomer and at least one other organic unsaturated comonomer, which is copolymerized into a solid state containing a small amount of unreacted monomer. an oxygen permeable polymeric material for a hard contact lens comprising selecting an oxygen permeable polymeric material and exposing said material to high energy radiation to reduce the amount of unreacted monomer and improve its dimensional stability. A method for improving the dimensional stability of polymeric materials. 2 If the polymer material is (a) the following formula (wherein R ₁ is selected from hydrogen or a methyl group, a is an integer from 1 to 3, b and c are integers from 0 to 2, d is an integer from 0 to 1, and A is selected from a methyl or phenyl group. , R ₂ is selected from a methyl or phenyl group, and R ₃ and R ₄ represent a c to d cyclic ring or represent either a methyl or a phenyl group).
(b) 5-60% by weight of itaconic acid mono- or diester; (c) _C1 - _C20 monohydric or polyhydric alkanol or phenol with an acid selected from acrylic acid or methacrylic acid. from a polymer formed from 1 to 60% by weight of an ester, (d) 0.1 to 10% by weight of a cross-linking agent, and (e) 1 to 20% by weight of a hydrophilic monomer that imparts hydrophilicity to the surface of the contact lens material. The method according to item 1, consisting essentially of: 3 Siloxanyl alkyl ester monomer (a) is 40
Itaconate ester (b) present in an amount of ~55% by weight
is present in an amount of 20 to 40% by weight, and ester (c) is present in an amount of 20 to 40% by weight.
40% by weight, the cross-linker is present in an amount of 0.1-10% by weight, and the hydrophilic monomer accounts for 1% of the total composition.
2. The method of claim 2, wherein the compound is present in an amount of ~20% by weight. 4 (a) Structural formula (wherein X and Y are selected from the group consisting of _C1 - _C5 alkyl groups, phenyl groups and Z groups, and Z is A is selected from a _C1 - _C5 alkyl group or a phenyl group, R is selected from a methyl group or hydrogen, m is an integer from 1 to 5, and n is a group from 1 to 5.
an integer of 3) having a polysiloxanyl alkyl ester of about 10
and (b) about 40 to 90 parts by weight of an ester of a _C1 to _C20 monohydric alkanol with an acid selected from acrylic acid or methacrylic acid. Selecting a polymeric material that is a polymer, the above copolymer containing a small amount of unreacted monomer, and in order to reduce the amount of unreacted monomer and improve dimensional stability. 2. The method of claim 1, comprising exposing said copolymer to high energy radiation. 5 Siloxanyl alkyl ester vinyl monomer, itaconic acid ester, acrylic acid ester,
and a monomer selected from the group consisting of methacrylic acid esters and mixtures thereof, and to reduce the amount of unreacted monomer and improve dimensional stability. To,
2. The method of claim 1, comprising treating the material as described above with high-energy radiation. 6 The siloxanyl alkyl ester vinyl monomer has the following formula: (wherein R ₁ is selected from hydrogen or methyl group,
a is an integer from 1 to 3, b and c are integers from 0 to 2, A is selected from methyl or phenyl group, R ₂ is selected from methyl or phenyl group, R ₃ and R ₄ are cyclic from c to d represents a ring or represents either a methyl or phenyl group, and d is 0 to 1
) is an integer of . 7. The method according to item 1, wherein the high-energy radiation is a gamma ray, and the polymer material absorbs 0.005 to 10 megarads of the radiation. 8. The method according to item 2 above, wherein the high-energy radiation is a gamma ray, and the polymer material absorbs 0.005 to 10 megarads of the radiation. 9. The method according to item 4, wherein the high-energy radiation is a gamma ray, and the polymer material absorbs 0.005 to 10 megarads of the radiation. 10. The method according to item 5 above, wherein the high-energy radiation is a gamma ray, and the polymer material absorbs 0.005 to 10 megarads of the radiation. 11. The method according to item 1, wherein the high-energy radiation is selected from the group consisting of X-rays, gamma rays, accelerated electron beams, neutron beams, and alpha rays. 12. The method according to item 2, wherein the high-energy radiation is selected from the group consisting of X-rays, gamma rays, accelerated electron beams, neutron beams, and alpha rays. 13. The method according to item 4, wherein the high-energy radiation is selected from the group consisting of X-rays, gamma rays, accelerated electron beams, neutron beams, and alpha rays. 14. The method according to item 5, wherein the high-energy radiation is selected from the group consisting of X-rays, gamma rays, accelerated electron beams, neutron beams, and alpha rays. 15 The polymeric material contains less than about 4% by weight of unreacted monomer before exposure to high-energy radiation and less than 1/2% by weight of unreacted monomer after exposure to high-energy radiation. Method described. 16 Item 2 above, wherein the polymeric material contains less than about 4% by weight of unreacted monomer before exposure to high-energy radiation and less than 1/2% by weight of unreacted monomer after exposure to high-energy radiation Method described. 17 The polymeric material contains less than about 4% by weight of unreacted monomers before exposure to high-energy radiation and less than 1/2% by weight of unreacted monomers after exposure to high-energy radiation. Method described. 18 Item 5 above, wherein the polymeric material contains less than about 4% by weight of unreacted monomer before exposure to high-energy radiation and less than 1/2% by weight of unreacted monomer after exposure to high-energy radiation Method described. 19 Selecting a solid copolymerized oxygen-permeable polymeric material consisting of a silicone-containing monomer and at least one other organic unsaturated comonomer and containing a small amount of unreacted monomer. and exposing the material to high-energy radiation to reduce the amount of unreacted monomer and improve the dimensional stability of an oxygen-permeable polymeric material for hard contact lenses. Method. 20. In a method of manufacturing an oxygen permeable hard contact lens from a polymeric material formed from 2 or more monomers and having not more than about 4% by weight of unreacted monomers, the unreacted monomers In order to reduce the amount of and improve dimensional stability,
An improved method consisting of treating the above materials with high-energy radiation in the range 15-0.003 Me.v. 21 The polymeric material contains less than about 4% by weight of unreacted monomer before exposure to high-energy radiation and less than 1/2% by weight of unreacted monomer after exposure to high-energy radiation Method described. 22 Oxygen permeable polymer composed of a siloxanyl alkyl ester vinyl monomer and at least one other organic unsaturated comonomer, copolymerized into a solid state containing a small amount of unreacted monomer. Select the material,
and an oxygen-permeable polymeric material for hard contact lenses, characterized in that the material is exposed to high-energy radiation to reduce the amount of unreacted monomer and improve dimensional stability. 23 If the polymer material is (a) the following formula (wherein R ₁ is selected from hydrogen or a methyl group, a is an integer from 1 to 3, b and c are integers from 0 to 2, d is an integer from 0 to 1, and A is selected from a methyl or phenyl group. , R ₂ is selected from a methyl or phenyl group, and R ₃ and R ₄ represent a cyclic ring or represent either a methyl or a phenyl group).
(b) 5-60% by weight of itaconic acid mono- or diester; (c) _C1 - _C20 monohydric or polyhydric alkanol or phenol with an acid selected from acrylic acid or methacrylic acid. from a polymer formed from 1 to 60% by weight of an ester, (d) 0.1 to 10% by weight of a cross-linking agent, and (e) 1 to 20% by weight of a hydrophilic monomer that imparts hydrophilicity to the surface of the contact lens material. The preceding paragraph 22 consisting essentially of
The oxygen permeable polymer material for hard contact lenses described above. 24 (a) Structural formula (wherein X and Y are selected from the group consisting of _C1 - _C5 alkyl groups, phenyl groups and Z groups, and Z is A is selected from a _C1 - _C5 alkyl group or a phenyl group, R is selected from a methyl group or hydrogen, m is an integer from 1 to 5, and n is a group from 1 to 5.
an integer of 3) having a polysiloxanyl alkyl ester of about 10
and (b) about 40 to 90 parts by weight of an ester of a _C1 to _C20 monohydric alkanol with an acid selected from acrylic acid or methacrylic acid. Selecting an oxygen-permeable polymeric material in which the copolymer contains a small amount of unreacted monomer, and reducing the amount of unreacted monomer and improving dimensional stability. 23. The oxygen-permeable polymer material for hard contact lenses according to item 22 above, which is obtained by treating this copolymer by exposing it to high-energy radiation in order to achieve the desired effect. 25 Select a solid copolymer material of siloxanyl alkyl ester vinyl monomer and a monomer selected from the group consisting of itaconate esters, acrylate esters, methacrylate esters and mixtures thereof and Item 2 above, wherein the material is treated with high-energy radiation to reduce the amount of reactive monomers and improve dimensional stability.
2. The oxygen permeable polymer material for hard contact lenses according to 2.