JP2503028B2 - Contact lens manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel method for producing a contact lens, and more particularly to a method for producing an excellent contact lens by a cast polymerization method. is there.

[Prior Art] Conventionally, as a method of manufacturing a contact lens, a race cut method for obtaining a desired contact lens by cutting and polishing a block copolymer of an appropriate size, a receiver having a predetermined shape is rotated. Then, the monomer is injected therein, and the monomer is injected into a casting mold molded to obtain a desired lens and a spin casting method for producing a contact lens by polymerization, and the monomer is injected by heat or light. There is a casting polymerization method in which the lens is taken out from the casting mold after polymerization and polymerization.

The race cut method is a widely used contact lens manufacturing method and has the advantage of being a small-quantity, high-mix manufacturing method, but it has many manufacturing steps, is complicated, and requires a skilled lens manufacturing staff. At the same time
It is difficult to remove polishing scratches on the lens surface, and as a result, stains are likely to adhere when the contact lens is worn.

The contact lens manufacturing method using the spin cast method has the advantage that it is possible to manufacture a lens with a thin wall thickness, which is not possible with the race cut method, and has the advantage of a short lens manufacturing time. It has a drawback that it is difficult to obtain sufficient accuracy of the base curve surface.

In the cast polymerization method, the number of manufacturing steps is small, and it is possible to manufacture contact lenses without polishing scratches on the lens surface.However, conventional cast polymerization technology is limited to the manufacture of soft contact lenses. As an example, for example, an example using fluoroethylene-fluoropropylene resin (FEP) or polyethylene (PE) as a casting material disclosed in JP-A-54-43268, and JP-A-57-98324 Examples using PE, polypropylene (PP), etc. disclosed in Japanese Patent Laid-Open No. 59-95118 and Japanese Patent Laid-Open No. 52-117647.
Examples thereof include PE disclosed in JP-A No. 57-90, an ethylene-vinyl acetate copolymer, nylon 11 and the like, and examples using PP disclosed in JP-A-57-609.

[Problems to be Solved by the Invention] Generally, the problems of the casting polymerization method include the molding accuracy of the casting material used and the releasability between the casting mold and the polymer lens. In the prior art, the casting material was selected with a focus on releasability. That is, in the conventionally used resins, the mold releasability after polymerization of the monomer is good, but the thermal and temporal shape and dimension stability of the casting material are not sufficient, and therefore the performance of the contact lens is improved. As a result, it is difficult to obtain an appropriate refracting power and sufficient standard shape and dimension accuracy, and it is inevitably limited to the soft contact lens manufacturing method. On the other hand, if the casting material is selected by giving priority to the accuracy of the shape and dimension of the casting material over time and time, the above-mentioned problem seems to be solved. Examples of such casting materials include polymethylmethacrylate, polystyrene, polycarbonate, polysulfone, polyether, polyetherketone, polyphenylene sulfide, and the like. However, when casting polymerization is performed using these resins as casting materials, the casting materials themselves are dissolved and deteriorated by the injected monomers,
There is a problem in that the contact lens cannot be molded, the adhesive force between the casting mold and the polymer lens becomes strong, and the polymer lens is deformed or damaged at the time of mold release, resulting in a significant decrease in molding yield. Furthermore, when trying to solve such a mold release problem by selecting the type of monomer to be injected, the applicable monomers are significantly limited, and the cast polymerization method cannot be applied to any composition. Such a drawback will occur. In addition, in order to solve the problem of mold release, in the method of including a mold release agent such as silicone in advance in the casting surface or the monomer,
There are problems that the molded lens polymer does not have sufficient surface accuracy as an optical product, or that it becomes cloudy.
That is, in the prior art, if a casting material is selected with an emphasis on releasability, the shape and dimension accuracy of the contact lens to be molded will be insufficient. In the case of selection, there is a practical problem that the quality of the casting material is deteriorated and the releasability is remarkably lowered, and even if molding is possible, the applicable monomer composition is significantly limited. It was

The object of the present invention is to solve the above-mentioned problems of the prior art,
It is an object of the present invention to provide a method capable of producing a contact lens having excellent shape and dimension accuracy with good releasability from a monomer having an arbitrary composition by the cast polymerization method. That is, the present invention is intended to enable the production of a soft contact lens having a shape and dimension accuracy, which has not been obtained in the prior art, by a cast polymerization method with good mold releasability. The object of the present invention is to make it possible to manufacture a harsh hard contact lens by a cast polymerization method with good releasability. Another object of the present invention is to make it possible to manufacture a contact lens having excellent shape and dimension accuracy in a short time with good releasability.

[Means for Solving the Problems] As a result of intensive studies for achieving the above-mentioned object, the present inventors have selected an ethylene-vinyl alcohol copolymer as a casting material, and selected the ethylene-vinyl alcohol copolymer. When the surface of the casting mold made of the united body is treated to be water-repellent, and then a monomer is injected into the casting mold to perform casting polymerization, the above-mentioned drawbacks of the prior art are solved, and a contact lens excellent in shape dimension stability is obtained. It has been found that good releasability can be obtained.

Therefore, the method for producing a contact lens of the present invention is characterized in that after the surface of a casting mold made of an ethylene-vinyl alcohol copolymer is treated to be water-repellent, a monomer is injected into the casting mold to carry out casting polymerization. And

 The preferred embodiments of the present invention are as follows.

(1) In the present invention, the water repellent treatment on the surface of the casting mold is performed by drying the casting mold and then using a general formula in a solvent. (In the formula, R ₁ is an alkyl group having 1 to 16 carbon atoms or a substituted or unsubstituted phenyl group.) (In the formula, at least one of X ₁ , X ₂ , X ₃ , and X ₄ bonded to Si is a halogen element or an acid amide group, and the rest are alkyl groups having 1 to 16 carbon atoms) Preference is given to using at least one of the compounds represented as treating agent.

(2) It is preferable to dry the casting mold by drying the casting material at a temperature of 60 ° C. or lower for 3 hours or more.

(3) The solvent used is an aliphatic hydrocarbon, alicyclic hydrocarbon or aromatic hydrocarbon having 16 or less carbon atoms in the molecule, or one or more oxygen atoms in the molecule. Alternatively, it is preferable to use one or a mixture of two or more kinds selected from aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons or heterocyclic compounds containing a nitrogen atom or both atoms at the same time. preferable.

 The present invention will be described in detail below.

The casting mold material used in the present invention is an ethylene-vinyl alcohol copolymer (hereinafter referred to as EVAl),
The casting mold is manufactured by a usual plastic molding method such as injection molding, compression molding or injection compression molding. The casting mold consists of a pair of male and female, and both are used as a mating mold. The water repellent treatment of the surface of the casting mold is performed by sufficiently drying the casting mold, immersing it in a solvent, and adding the compound of the general formula (I) and / or the compound of the general formula (II) as a treating agent. Preferably by Here, in order to sufficiently carry out the surface water repellent treatment, it is preferable to perform vacuum drying at a temperature of 60 ° C. or lower for 3 hours or longer, particularly 24 hours or longer in the presence of a suitable desiccant. As the desiccant, for example,
Examples thereof include silica gel, calcium chloride, phosphorus pentoxide and the like. In addition, it is not preferable to dry the casting mold at a temperature higher than 60 ° C., because it may cause deformation. If the drying time is less than 3 hours, the water content on the surface of the casting mold may not be completely removed. The dry EVAl casting mold is then immersed in a suitable solvent. Examples of the solvent include benzene, toluene, xylene, n-hexane, tetrahydrofuran, anisole, pyridine, morpholine and the like. Use a sufficient amount of solvent for the casting mold. If the amount of the solvent is too small, it becomes difficult to uniformly treat the surface of the casting mold.

Next, the treating agent is added to this solution. As the treating agent, as described above, the compounds of the general formula (I) and the general formula (II) are preferable, and typical examples of the compound of the general formula (I) include acid chlorides such as acetyl chloride, propionyl chloride and benzoyl chloride. Further, typical examples of the compound of the general formula (II) include silylating agents such as trimethylchlorosilane, dimethyldichlorosilane and N-trimethylsilylacetamide. Unless N-trimethylsilylacetamide is used as the treating agent or pyridine, piperidine, morpholine or the like, which is a basic solvent, is used as the solvent, the reaction usually proceeds promptly because the addition of a base is usually performed. preferable. Examples of the base include triethylamine, pyridine, piperidine, morpholine, ammonia and the like. The amount of the treatment agent added is preferably 0.5% by weight or more, and if it is less than this, unevenness may occur in the water repellent treatment. When a base is added, it is added in an amount of 1 to 30% by weight, more preferably 5 to 20% by weight, based on the solvent. The water repellent treatment time is preferably 30 minutes or longer. If the treatment time is too short, the water repellent treatment may not be completed. The treatment temperature is preferably 50 ° C or lower. If the temperature is higher than 50 ° C, the reaction may be too violent and the cast optical surface may be roughened. After completion of the treatment, the casting mold is promptly taken out of the solution, thoroughly washed with the same solvent as the treated solvent, and then the casting mold is thoroughly dried. The thus obtained pair of male and female casting molds is used to homopolymerize or copolymerize the monomers to obtain a desired contact lens.

The monomer as the contact lens material used in the present invention is not particularly limited as long as it is a monomer usually used as a contact lens material, and may be used alone or in combination of two or more kinds. Examples of the monomer include (meth) acrylic acid and / or its esters. Examples of the (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate,
n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate,
i-Butyl (meth) acrylate, t-butyl (meth)
Not only hydrocarbon-based derivatives such as acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, n-octyl (meth) acrylate and benzyl (meth) acrylate, but also 2-trifluoroethyl (meth) acrylate and hexafluoro Fluorine-containing (meth) acrylates such as i-propyl (meth) acrylate and tris (trimethylsiloxy) silylpropyl (meth) acrylate, tris (dimethylsiloxy)
Silicon-containing (meth) acrylates such as silylpropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, glyceryl mono (meth) acrylate, (meth) acrylamide, N-methyl. (Meth) acrylamide, N, N-dimethyl (meth) acrylamide,
Hydrophilic monomers such as N-vinylpyrrolidone are mentioned. Furthermore, in the present invention, a cross-linking agent usually used for imparting desired physical properties to a polymer lens is a (meth) acrylate having at least two double bonds in the molecule, that is, allyl (meth). Acrylate,
Ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, etc. and trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, etc. Is mentioned.

Homopolymerization or copolymerization of the above monomers is carried out at a temperature of 120 ° C. or lower in the presence of a radical polymerization initiator. The radical polymerization initiator is not particularly limited as long as it is an initiator used for vinyl polymerization, for example, azobisisobutyronitrile, azobisdimethylvaleronitrile, benzoyl peroxide, lauryl peroxide, diisopropyl peroxycarbonate and the like. Is mentioned. The amount of the polymerization initiator added is 0.01 to 3.00% by weight with respect to the total amount of monomers,
More preferably, it is 0.03 to 1.00 weight percent. The polymerization time is usually in the range of 2 hours to 72 hours. More preferably, it is usually in the range of 35 ° C to 45 ° C, and is 1 to 8
After gradually advancing the polymerization for an hour, the temperature is raised to 80 to 90 ° C,
Hold for 3-8 hours to complete polymerization. Let the casting mold stand at room temperature, divide the casting mold and take out the lens polymer. In the case of a water-containing soft contact lens material, it can be obtained by hydration and swelling in 0.9% by weight of physiological saline after polymerization.

[Examples] The present invention will be described in more detail with reference to Examples.

Example 1 (a) Molding of casting mold An ethylene-vinyl alcohol copolymer (EVAl ... Nippon Synthetic Chemical Industry Co., Ltd.) was prepared by injection molding on a mold having an optical surface diameter of 8.8 mm and a center curvature radius of 8.00 mm. GL manufactured by Kogyo Co., Ltd.
Make a male mold using resin. Diameter of cast optical surface 8.
A female mold made of EVAl is made by injection molding using a mold having a center radius of curvature of 8.50 mm and 9 mm. The dimensions of the injection-molded male mold are as follows: center radius of curvature 7.99 ± 0.006 mm, diameter of optical surface
It was 8.79 ± 0.006 mm. Also, the female mold has an outer diameter of 23.
The diameter was 99 ± 0.006 mm, the diameter of the optical surface was 8.8 ± 0.005 mm, and the center radius of curvature was 8.49 ± 0.005 mm. Both male and female molds had extremely good dimensional accuracy, and the molded optical surface was very smooth.

(B) Water repellent treatment of casting surface A set of castings obtained in (a) was vacuum dried over phosphorus pentoxide at room temperature for 24 hours, and then toluene was used as a solvent in 100 ml of the solvent. And add 15 g of triethylamine as a base. After that, 6.5 g of acetyl chloride as a treatment agent
Was gradually added and reacted at a temperature of 50 ° C. or lower for 4 hours.
Then, the surface of the casting mold was thoroughly washed with 300 ml of a toluene solution, and then steam cleaning of the casting mold was performed with chlorofluorocarbon. The casting mold after the above treatment was vacuum dried on phosphorus pentoxide at a temperature of 60 ° C. or lower for 24 hours. The water repellent treatment was evaluated using a goniometer, and the contact angle with water was measured to be 88 ° C, and the untreated casting mold had a contact angle of 72 °. It was shown that it was done.

(C) Cast Polymerization of Lens Cast polymerization of the lens was performed using 20 sets of casting molds whose surface was made water repellent in (b). That is, 98 parts by weight of purified methyl methacrylate, 10 parts by weight of ethylene glycol dimethacrylate, and 0.3 parts by weight of azobisisobutyronitrile as a polymerization initiator were stirred until they were sufficiently homogeneous, and about 150 mg of this solution was put into a female mold. Insert and gently cover the male mold from above. The set of casting molds which had been filled with the monomers was then subjected to heat polymerization in a hot air circulating constant temperature bath. Polymerization was carried out at 40 ° C. for 1.5 hours, from 40 ° C. to 90 ° C. over 15 hours, and at 90 ° C. for 4 hours. Then, after cooling to room temperature, the casting mold was opened and the lens polymer was taken out. During this release, a lens that did not become a good lens due to deformation damage and the like was regarded as defective, and the yield of good products was calculated to be 85%, which was a very good release property. The diameter of the contact lens obtained as a good product is 8.79 ± 0.00
6 mm, the refractive power was −2.90 ± 0.04 Geopretley, and the molding precision was also very good.

Example 2 Similar to (a) of Example 1, except that the radius of curvature of the casting mold was set to 5.01 mm for the male mold, 5.45 mm for the female mold, and the diameter of the optical surface was set to 8.49 mm for the male mold and 8.50 mm for the female mold. EVAl casting molds were molded, and 20 sets of the casting molds were subjected to surface water-repellent treatment in the same manner as in (b) of Example 1. Example except that the monomers injected into the casting mold were N-vinylpyrrolidone 88 parts by weight, benzyl methacrylate 12 parts by weight, triethylene glycol dimethacrylate 0.3 parts by weight, and the initiator was azobisisobutyronitrile 0.3 parts by weight. Cast polymerization was carried out in the same manner as in 1 (c). Thereafter, the lens polymer thus obtained was adjusted to 0.
Hydration and swelling was carried out at 80 ° C. for 2 hours in a physiological saline solution of 9 weight percent, and the temperature was returned to room temperature to obtain a desired soft contact lens. Among the lenses thus obtained, the yield of good lenses is 80%, and the molding accuracy is 13.50 ± 0.007 mm in diameter,
The refractive power was −2.80 ± 0.06 diopters and had excellent molding accuracy.

Example 3 An EVAl casting mold was produced in the same manner as in Example 2, and 20 sets of this casting mold were subjected to surface water repellent treatment. The treatment method is almost the same as that in (b) of Example 1, except that pyridine is used as the solvent. The contact angle between the cast mold and water after treatment was measured with a goniometer.
° C. Purified using these 20 sets of casting molds
Cast polymerization was carried out on a monomer mixture consisting of 70 parts by weight of hydroxyethyl methacrylate, 20 parts by weight of methyl methacrylate, 2 parts by weight of methacrylic acid, 0.3 part by weight of vinyl methacrylate and 0.5 part by weight of azobisisobutyronitrile. As a result, the yield of non-defective lenses was 90%. This lens was hydrated and swollen in physiological saline in the same manner as in Example 2 to obtain a soft contact lens. The molding precision of this soft contact lens is 13.02 ± 0.008m in diameter
It was m, the refractive power was −2.75 ± 0.07 diopters, and it was revealed that the obtained contact lens had excellent molding accuracy regardless of the kind of the monomer, as in Example 2 described above.

Examples 4 to 16 For the hard contact lens material, cast molding was performed according to (a) of Example 1, and for the soft contact lens material, cast molding was performed according to Example 2. Further, the cast mold thus obtained was subjected to a surface water-repellent treatment by changing the treating agent, solvent and base. The results are shown in Table 1. The contact angle with water was measured at 88 ° to 95 °. Using 20 sets of casting molds that have each been made water repellent,
Polymerization of various monomers was performed. The yield was good in all of the examples, and the yield of good lenses due to releasability was 85 to 95%. Also, the molding accuracy of the lens is
The diameter was ± 0.004 to 0.008 mm, and the refractive power was ± 0.01 to 0.08 diopters.

The molding accuracy was very good regardless of whether it was a hard contact lens or a soft contact lens.

Comparative Example 1 The same operation as in Example 1 was performed, except that an untreated EVAl casting mold that was not subjected to water repellent treatment was used. Untreated EVAl
The contact angle of the casting mold with water was 72 °. Using this casting mold, casting polymerization was carried out with a composition of 98 parts by weight of methyl methacrylate, 10 parts by weight of ethylene glycol dimethacrylate, and 0.3 parts by weight of an initiator. The yield was 25%, and most of the lenses were damaged or greatly deformed during release, making them unusable. Lens molding accuracy is 8.97 in diameter
The refractive power was ± 0.008 mm and the refractive power was −2.90 ± 0.07 diopters.

Comparative Example 2 Cast polymerization was carried out in the same manner as in Example 2 except that an untreated casting mold was used without the water-repellent treatment.

The yield was 15%, and most of the lenses markedly adhered to the mold material, and the lenses were damaged during release. The molding precision of the lens was a diameter of 13.50 ± 0.008 mm and a refractive power of −2.85 ± 0.10 diopters.

Comparative Example 3 A polypropylene (PP) casting mold was prepared in the same manner as in (a) of Example 1. The dimensions of the injection-molded male mold are as follows: center radius of curvature 7.99 ± 0.02 mm, optical surface diameter 8.79 ±
It was 0.02 mm. Also, the female type has a central radius of curvature of 8.49.
It was ± 0.02 mm and the diameter of the optical surface was 8.8 ± 0.02 mm. The contact angle of this casting with water was 91 °. Using 20 sets of casting molds thus obtained, casting polymerization was performed in the same manner as in Example 1 (c). The yield of non-defective lenses is 95%, the molding accuracy of lenses is 8.79 ± 0.035 mm, and the refractive power is −2.90 ± 0.20.
It was diopter. The molding precision was inferior to that of Example 1.

Comparative Example 4 In the same manner as in Comparative Example 3, 20 sets of PP casting molds were produced and cast polymerization was carried out in the same manner as in Example 2. The yield of good lenses is
The molding accuracy of the lens was 90%, the diameter was 13.40 ± 0.045 mm, and the refractive power was −2.80 ± 0.22 diopters.

Comparative Example 5 A casting mold made of high-density polyethylene (HDPE) was prepared by the same method as in (a) of Example 1. The injection-molded male mold had a center radius of curvature of 7.99 ± 0.02 mm and an optical surface diameter of 8.79 ± 0.02 mm. The female mold had a central radius of curvature of 8.47 ± 0.03 mm and the optical surface had a diameter of 8.8 ± 0.03 mm. The contact angle of this casting with water was 90 °. Using 20 sets of this casting mold, the same polymerization as in (c) of Example 1 was carried out. The lens yield was 80% from the viewpoint of releasability, but the lens deformation was so great that the lens molding accuracy could not be measured.

Comparative Example 6 An EVAl casting mold formed in the same manner as in (a) of Example 1 was thinly and uniformly coated with a silicone release agent and dried,
Cast polymerization was carried out in the same manner as in (c) of Example 1. The polymer lens had excellent releasability, but the optical surface was rough and the lens became cloudy.

[Effects of the Invention] According to the method for manufacturing a contact lens of the present invention, the yield of molded lenses is extremely good, and the molding accuracy of the obtained lenses is significantly improved. This effect remarkably demonstrates the effectiveness of the surface water repellent treatment of the casting mold made of the ethylene-vinyl alcohol copolymer disclosed by the present invention. Further, the method for producing a contact lens of the present invention not only provides sufficiently good molding accuracy even for a hard contact lens having a severe standard shape dimensional accuracy of a lens, which has not been obtained by a conventional method, but can be used as a lens material. It has wide applicability to the above monomers. The excellent effects as described above are made possible only by using the ethylene-vinyl alcohol copolymer disclosed and exemplified by the present invention as a casting material and subjecting the surface of the casting mold to a water-repellent treatment. This is an effect peculiar to the present invention.

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Claims (1)

(57) [Claims] 1. A method for producing a contact lens, which comprises subjecting a surface of a casting mold made of an ethylene-vinyl alcohol copolymer to a water-repellent treatment and then injecting a monomer into the casting mold to carry out casting polymerization. Method.