JP2003103532A - Method of manufacturing ophthalmic lens - Google Patents

Abstract

(57) [Summary] [Constitution] The present invention improves the accuracy of cutting in the manufacturing process of an ophthalmic lens by a one-sided cutting method in which an inner surface is completed by thermal polymerization using a mold and an outer surface is completed by cutting. Provided is a method for manufacturing an ophthalmic lens that can increase the percentage of processed non-defective products. SOLUTION: By providing an existing mechanism for 3 minutes or more between the polymerization step and the cutting step, it is possible to realize the production of a lens having a high yield rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention forms the inner surface (base curve surface) of an ophthalmic lens by transfer from a mold, and the other surface (front curve surface) of the eye lens half on the mold used for transfer. In a manufacturing method of an ophthalmic lens formed by cutting with a product attached, the present invention relates to a method of precisely cutting a polymerized semi-finished ophthalmic lens product.

[0002]

2. Description of the Related Art Conventionally, in a method for manufacturing an ophthalmic lens, a molten resin is injection-molded in a mold which forms a space corresponding to the lens shape, or a lens space is formed by a resin mold. There are a method of pouring a polymerizable monomer therein to polymerize a lens, and a method of cutting an ophthalmic lens material into a desired shape.

The method of directly molding the final product into the shape of an ophthalmic lens in a mold and the method of polymerizing a polymerizable monomer in a resin mold enable a mass production because the manufacturing process can be simplified. However, in order to manufacture lenses having various standards, molds and molds corresponding to them are required, and there is a problem in maintenance and management. On the other hand, the method of cutting an ophthalmic lens material into a lens by cutting requires a larger number of steps than the case of using the above-mentioned mold or mold, and thus is slightly inferior in terms of mass production. It is convenient for producing a wide variety of lenses with different specifications.

In recent years, the market for contact lenses of the ophthalmic lens type, which are frequently and periodically replaced, has expanded, and it has become necessary to supply a large amount as the demand increases. Such a lens is a soft hydrogel contact lens and is usually produced by the method using the above-mentioned mold / mold. However, this production method cannot be said to be necessarily an appropriate method because it is necessary to maintain and manage the molds that meet various standards as described above. Therefore, a single-sided cutting method, which is a mixture of the above-mentioned cutting method and this molding method, has been proposed. In this method, one surface of the lens is formed by transfer from a mold, and the other surface is completed by cutting. In general, soft hydrogel contact lenses have a soft material, so that the comfort of wearing to different eyes of many patients is deteriorated without preparing a lens having a multi-standard inner curvature unlike hard contact lenses. It suffices to prepare a lens that fits flexibly without causing the inner surface curvature of almost one or two kinds of standards. Therefore, the single-sided cutting method shortens the processing process by transferring the inner surface of the lens from the mold, and finishes the outer surface of the lens by cutting so that it can be applied to patients who require different corrected visual acuity, and the required metal It can be said that this is a method of achieving both mass production of lenses and reduction of manufacturing cost by reducing the mold standard as much as possible and facilitating the manufacturing cost and maintenance of the mold itself.

In the single-sided cutting method, a raw material monomer is usually filled in a space between a male mold and a female mold and polymerized to produce a semi-finished ophthalmic lens product, and then the female mold is removed to remove the ophthalmic lens semi-finished product. The product is cut while being attached to the male convex surface. Polymerization of the raw material monomer is usually thermal polymerization or ultraviolet polymerization, but in the case of thermal polymerization, if the female mold is removed after the polymerization is completed and the lens semi-finished product is immediately attached to the convex surface of the male mold, cutting is performed. There is a problem that the defective rate in cutting is high.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the circumstances as described above, and improves the accuracy of the cutting process in the cutting process of a semi-finished product for an ophthalmic lens in the single-sided cutting method, It is an object of the present invention to provide a method for manufacturing an ophthalmic lens capable of reducing the defective rate.

[0007]

In order to achieve the above object, the present invention is characterized by having the following constitution. That is, according to the present invention, a raw material monomer is filled in a space between a male mold and a female mold, and heat-polymerized to produce an ophthalmic lens semi-finished product, and then the female mold is removed to produce the ophthalmic lens semi-finished product by the male mold. The inner surface (base curve surface) of the ophthalmic lens is formed by transfer from the mold by cutting while attached to the convex surface of the eye lens, and the other surface (front curve surface) is formed by cutting processing. The method of manufacturing an ophthalmic lens, wherein the semi-finished product for ophthalmic lens adhered to the convex surface of the male mold is allowed to pass for at least 3 minutes from the end of polymerization to the cutting step.

In the single-sided cutting method targeted by the present invention, the inner surface of the lens is already completed by molding, so that the outer surface side is cut to obtain a finished lens. At that time, if the semi-finished product for ophthalmic lenses is removed from both molds and cut, the surface fixed to the cutting machine becomes the inner surface of the lens, so the optical surface finished by the mold is damaged or a cutting bit at the time of processing. The outer surface is usually processed while it is still attached to the mold forming the inner surface side, for example, because it cannot be sufficiently finished due to the pressure of.

When mass-producing an ophthalmic lens by a single-sided cutting method, the ophthalmic lens is attached to the male mold after polymerizing a raw material monomer filled in a space between the male mold and the female mold and then removing the female mold. Semi-finished products are continuously transferred to the cutting process and the outer surface (front curve surface) is cut. However, if the outer surface of the semi-finished ophthalmic lens polymerized by thermal polymerization is continuously cut after the polymerization step as described above, there arises a problem that the cutting accuracy is low and the processing defect rate is high.

The method of the present invention solves the above-mentioned problems by allowing it to remain for at least 3 minutes from the end of the thermal polymerization step for the manufacture of the above-mentioned semifinished ophthalmic lens to the start of the cutting step. It is possible to improve the cutting accuracy of the outer surface of the semi-finished ophthalmic lens product and reduce the processing defect rate of the final product. When cutting is performed after a certain time has passed from the end of the thermal polymerization step, the cutting accuracy improves,
It is not completely clear why the defective processing rate is low,
It seems that the coefficient of thermal expansion of the lens material and the molding material, the temperature change of the flexibility of the molding material, etc. are complicatedly related.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the above drawings with reference to the accompanying drawings.

In the method for manufacturing an ophthalmic lens of the present invention, first, a male mold 1 and a female mold 2 as shown in FIG. 1 are molded by an injection molding method, a thermal compression molding method, or the like. The materials of the male mold 1 and the female mold 2 are polypropylene and polyamide (nylon 6
Etc.), polyester, polysulfone, polyacetal,
An ethylene-vinyl alcohol copolymer or the like is used.

Next, as shown in FIG. 2, the raw material monomer is filled in the space 3 between the male mold 1 and the female mold 2 and fitted. The monomer applicable to the present invention is a radically polymerizable compound, and a substance usually used as a soft contact lens material is used. For example 2-hydroxyethyl acrylate,
Methacrylic acid, alkyl (meth) acrylate, N-vinyl-2-pyrrolidone, N, N-dimethylacrylamide, siloxanyl (meth) acrylate, fluoroalkyl (meth) acrylate and others are used. Further, in the case of a highly hydrous soft contact lens, a macromer such as a (meth) acrylate polymer having a polymerizable group can be used as a reinforcing agent. As a cross-linking agent,
Ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate and the like are used.

In the one-sided cutting method, the male die 1 and the female die 2
It is desirable to select the material of the above according to the nature of the monomer used for polymerization. That is, when a hydrophilic monomer and a hydrophobic monomer are copolymerized, if a hydrophobic polymer such as polypropylene is used as the material of the mold, due to the affinity of the polymer used for the mold and the polymerized monomer, the surface of the polymerized lens is Hydrophobic monomers tend to collect. For this reason, compositional unevenness occurs on the surface and the inner surface of the polymerized lens, and there arises a problem that the lens is deformed when the outer surface of the semifinished lens product is subjected to hydration treatment after cutting. Such a tendency is remarkable when the thermal polymerization is carried out as in the present invention. Therefore, when copolymerizing a hydrophilic monomer and a hydrophobic monomer, it is desirable to use a material such as polyamide. Nylon 6 is particularly desirable.

As the polymerization initiator, radical polymerization initiators such as azobisisobutyronitrile, azobisdimethylvaleronitrile and benzoyl peroxide are used.

The polymerization of the monomer filled in the space 3 between the male mold 1 and the female mold 2 is carried out by heating. Specifically, the mold filled with the monomer is heated in a heating furnace at a temperature of 80 to 95 ° C. for 15 to 4 times.
It is carried out by letting it pass for 5 minutes. In this way, a semi-finished ophthalmic lens whose inner surface is formed by the convex surface of the male mold 1 is obtained.

Next, the female mold 2 is removed. Male type 1 mated
By inserting a means for fixing the female mold 2 between the female mold 2 and the female mold 2, and pushing it up from the direction of the outer surface 4 of the female mold 2, the polymerized semi-finished lens product can be opened in a state of being in close contact with the male mold 1. Then, the semi-finished ophthalmic lens product attached to the male mold is transferred to a cutting device. At this time, if the semi-finished ophthalmic lens product attached to the male mold is immediately set in a cutting device and cutting on the front curve side is performed, the accuracy of the cutting process decreases and the processing defect rate increases. Therefore, it is necessary to allow at least 3 minutes, preferably 5 minutes or more before setting in the cutting device after completion of the polymerization step.

Immediately after the thermal polymerization, the temperatures of the lens semi-finished product and the male mold are almost the same as the polymerization temperature. However, the temperature is lowered by allowing it to stand in a room temperature atmosphere for a certain period of time, and the temperature of the cutting working atmosphere becomes Get closer. It is desirable that the difference between the temperature of the lens semi-finished product and the male mold at the start of the cutting process and the temperature of the cutting atmosphere is within 10 ° C, preferably within 5 ° C. The temperature of the cutting atmosphere is usually room temperature of 15 to 30 ° C. When the lens semi-finished product and the male mold are left for 3 minutes or more, preferably 5 minutes or more in an atmosphere having substantially the same temperature as the cutting atmosphere, the temperature of the lens semi-finished product and the male mold is 10 times that of the cutting atmosphere. The difference is within ℃. After the completion of the polymerization process, the semi-finished ophthalmic lens product attached to the male mold is set in a cutting machine, and if the time until the cutting process is started is shorter than 3 minutes, the semi-finished ophthalmic lens product adhered to the male mold is completed. Since the temperature difference between the cutting atmosphere and the cutting atmosphere does not become sufficiently small, the processing defect rate increases. When the glass transition temperatures of the male and female materials are low, it is desirable that the above temperature difference be smaller, and that the temperature of the cutting atmosphere be set lower.

In the present invention, the male mold having the lens semi-finished product attached thereto, which has been transferred to the cutting process after the thermal polymerization process, is automatically attached to the chuck of the NC lathe for cutting the front curve. Although set, a mechanism for providing an interval of 3 minutes or more is provided between the thermal polymerization step and the lathe. This mechanism may be provided at any place between the thermal polymerization step and the cutting step, but may be provided near the lathe after transferring from the polymerization and female mold releasing step to the cutting step, for example. That is, exiting the thermal polymerization furnace, the male mold with the lens semi-finished product separated from the female mold is transferred to a cutting machine and automatically supplied to the holding mechanism, and after staying there for a certain period of time, The robot automatically sets it on the chuck of the lathe.

Next, one embodiment of the retaining mechanism used in the present invention will be shown. FIG. 3 shows the structure of the retaining mechanism 10. In FIG. 3, reference numeral 5 is an entrance into which the male mold 6 with the semi-finished lens product attached thereto is conveyed from the polymerization step and enters the holding mechanism. The retaining mechanism 10 has a disk 7 provided with a cutting portion 8 and is adapted to intermittently rotate one frame every 30 seconds. The male mold 6 with the semi-finished lens attached thereto enters the cutting mechanism 8 at the position 9 after entering the mechanism through the entrance 5. The male die 6 that has entered the excision portion 8 reaches the position 11 when the disk of the retaining mechanism 7 has rotated by 10 frames, and is separated from the disk 7 by gravity there. Disk 7
The male mold 6 which has separated from the main body passes through the meandering passage 12 and exits 13
Emitted from.

FIG. 4 shows a state in which the retaining mechanism of FIG. 3 is incorporated in the cutting device 14. The device 14 is an NC lathe for cutting a front curve. The male mold 6 to which the above-mentioned semi-finished lens product has been attached after the polymerization process and the female mold peeling process reaches the outlet 13 via the retaining mechanism 10 of FIG. Furthermore, male type 6 has exit 1
3 to the chuck 16 of the lathe 14 by the robot mechanism 15
Is automatically set on the chuck, and the outer surface of the semi-finished lens product attached to the male die 6 is cut.

The lens whose outer surface has been cut is then peeled off from the male mold. In this case, it is advantageous to use a two-step separation method as a method of separating the ophthalmic lens from the male mold, because the lens can be quickly separated without damage. That is, first, while fixing a part of the male mold part, a cylinder having a diameter of 4 to 12 mm is pressed concentrically from the surface opposite to the male lens forming surface to peel off the peripheral part of the lens which is initially attached. Then, the pressing force is released, and the pressing force is similarly applied to predetermined four places on the back surface, whereby the lens can be completely peeled off.

Example 1 and Comparative Example 1 Nylon 6 resin (NOVAMID ES11OC, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) was used to injection-mold 100 male and female molds as shown in FIG. As shown in FIG. 2, 40 parts of N-vinyl-2-pyrrolidone in the void 3 of the male mold 1 and the female mold 2,
A polymerization mixture of 40 parts of N, N′-dimethylacrylamide, 20 parts of a methacrylate polymer having a polymerizable group in the molecule, and 0.05 part of a polymerization initiator azobisdimethylvaleronitrile was filled and fitted. 4 in a 85 ° C polymerization furnace
Immediately after the polymerization for 0 minutes, the female mold was separated, and after an interval of 5 minutes by the retaining mechanism shown in FIG. 3, the female mold was set on the chuck of the NC lathe and the outer surface side was cut. After processing, the lens was peeled from the male mold, subjected to elution and hydration treatment, and then the lens standard inspection was performed. As a result, the non-defective rate was 98.5%.
On the other hand, in the case of transferring to the cutting process immediately after separating the female mold, setting it on the chuck of the lathe for cutting without using the retaining mechanism of FIG. 3, the yield rate was 78.5%.

[0024]

As described above, according to the manufacturing method of the present invention, in the manufacture of an ophthalmic lens by the single-sided cutting method, it is possible to improve the accuracy of cutting and reduce the defective rate of processing. Ophthalmic lenses can be mass-produced industrially very efficiently by the manufacturing method.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a molding die used in the present invention.

FIG. 2 is a cross-sectional view showing a fitted state of a male die and a female die in the forming die of FIG.

FIG. 3 is a plan view showing an embodiment of a retaining mechanism used in the present invention.

FIG. 4 is a plan view showing a cutting device incorporating the retaining mechanism of FIG.

[Explanation of symbols]

1 male 2 female 3 void 5 entrance Male type with semi-finished lens for 6 eyes attached 7 discs 8 excision part 10 Storage mechanism 13 exit 14 lathe 15 Robot mechanism 16 chuck

Claims (3)

[Claims] 1. A raw material monomer is filled in a space between a male mold and a female mold, followed by heat polymerization to produce a semi-finished ophthalmic lens,
By removing the female mold and cutting the semi-finished ophthalmic lens attached to the convex surface of the male mold, the inner surface of the ophthalmic lens is formed by transfer from the mold, and the outer surface is formed by cutting. In the method of manufacturing an ophthalmic lens,
A method for manufacturing an ophthalmic lens, characterized in that the semi-finished ophthalmic lens adhered to the male convex surface is left for at least 3 minutes from the end of the polymerization step to the start of the cutting step. 2. The method for manufacturing an ophthalmic lens according to claim 1, further comprising a mechanism for allowing the male mold with the semifinished ophthalmic lens attached to a convex surface to remain for a certain period of time before being set on a lathe for cutting. . 3. The holding mechanism inserts a male mold in which the semi-finished product for an eye is attached to a convex surface into an excision portion provided around the disk, and intermittently rotates the disk at regular intervals. 3. The method for manufacturing an ophthalmic lens according to claim 1, wherein the ophthalmic lens is removed from the disc after a predetermined storage time.