JP2003103537A - Lens mold opening means and lens mold opening method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an efficient mold separation means simple in mechanism and separating a mold assembly for molding an ophthalmic lens or a lens blank having a size capable of providing the ophthalmic lens by polymerizing a raw material monomer in the substantially hermetically closed space between a convex mold and a concave mold. SOLUTION: When the method for separating the mold assembly having first and second means is used, molds can be always easily separated in such a state that the ophthalmic lens or the lens blank is bonded to a definite mold. The first and second means are simple in mechanism and efficient mold separation means. Since the molds can be separated in such a state that ophthalmic lens or the lens blank is bonded to the definite mold, the mold assembly can be put on a series of automatic production lines and the lens can be mass-produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ophthalmic lens or a lens blank of a size capable of polymerizing a raw material monomer in a space substantially sealed between a convex mold and a concave mold to give an ophthalmic lens. The present invention relates to a mold separating means for separating a mold assembly for molding a mold, which has a simple mechanism and is efficient.

In particular, the present invention is a manufacturing method in which one surface of an ophthalmic lens is formed by transfer from a mold and the other surface is formed by cutting, and a mold assembly using the separating device is used. The present invention relates to a method for separating the lens blank so that the lens blank can be easily separated from the mold when the lens is opened and the lens optical surface is always left on the mold on the side where the lens optical surface is transferred.

[0003]

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 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.

[0005] 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, the production method of which is the mold
A method using a mold is adopted, and a monomer mixture (in particular, a solvent not involved in polymerization is generally added to reduce volume shrinkage due to polymerization) is used in a mold made of polystyrene or polypropylene. Producing by polymerizing is generally known in the prior art.

Molds for molding these contact lenses include a concave mold for forming a lens front surface called a front curve and a convex mold for forming a lens rear surface called a base curve. Then, the monomer mixture is filled in the space formed by combining these molds to polymerize, but at this time, in order to completely form the lens shape (effects such as polymerization shrinkage and the lens when the mold is assembled, Prior to mold assembly (so that there are no bubbles in the forming space), the concave mold is infused with excess monomer mixture. Upon polymerization, this excess monomer mixture formed an annular ring at the contacts of both molds in the mold assembly, which ring prevented separation of both molds.

Further, since the monomer mixture is closely adhered to the convex and concave surfaces of both molds and is polymerized, it is naturally difficult to separate the mold assembly, and at the same time, the lens blank formed in such a mold separating step is difficult. There was a case where the surfaces that were formed by being pulled by the respective contacting surfaces were scratched, cracked, or chipped. In order to solve these problems, various mold separation methods / devices have been conventionally proposed. For example,
Japanese Unexamined Patent Publication No. 7-329204 discloses a device that has fingers for restraining a flange portion of a mold and a separating finger arranged to face the flange, and rotates the separating finger with respect to the restraining finger to separate the molds. No. 8-99370 is a method of giving a temperature difference between molds and restraining it in a mold similar to the above, and applying a rotational force to separate them. In Japanese Patent Laid-Open No. 9-174706, infrared energy is applied to give the temperature difference. In Japanese Patent Application Laid-Open No. 10-71623, a device and method for projecting steam, steam, or uniform light energy includes a heating probe for conductively heating a mold, and heat generates a temperature gradient between the mold and the lens.
Disclosed are apparatuses for separating the molds by expanding and moving the mold surface with respect to the lens surface due to a temperature gradient, weakening the adhesiveness between the mold surfaces and leaving the lens in the front curve mold. There is.

According to the above-mentioned conventional technique, a mold separating device has been incorporated into an automation line to improve mass production efficiency. There are various methods for opening the mold, but for example, opening the mold with the lens always attached to a fixed mold is convenient for performing hydration treatment, lens inspection, etc. in a later step. , Especially by transferring one surface from the mold,
In the method of finishing one surface by cutting, it is desirable to remove the mold on the processed surface side and open the mold in a state of being attached to the transfer side mold. In the above-mentioned prior art, a temperature gradient is generated between the mold and the lens to weaken the adhesiveness between them, so that one mold can be easily removed from the lens. However, the method of generating a thermal gradient in this way is
(1) Polymerization in the mold is effective when a polymerization method that does not depend on heat such as photopolymerization is used. However, in the case of thermal polymerization, both the mold and the lens are formed in a hot state. It took time to hold it, or (2) a device such as a heating probe was required, and it was necessary to improve the time and the device configuration.

[0009]

DISCLOSURE OF THE INVENTION The present invention provides an ophthalmic lens or an ocular lens of a size capable of polymerizing a raw material monomer in a space substantially sealed between a convex mold and a concave mold. It is an object of the present invention to provide means for separating a mold assembly for molding a lens blank by a simple method. In particular, in a single-sided cutting method in which one side (preferably concave side) of a lens is molded by a mold, and the other side (preferably convex side) is processed by cutting, the lens is always left on the surface side mold formed by molding An object of the present invention is to provide a method for separating a mold assembly that separates a mold on the surface side.

[0010]

In order to achieve the above object, the present invention is characterized by having the following constitution. That is, a mold assembly for molding an ophthalmic lens or a lens blank of a size that can give an ophthalmic lens by polymerizing raw material monomers in a space that is substantially sealed between a convex mold and a concave mold is separated. In the means, (a) a first means for holding the concave mold of the mold assembly, and (b) a convex surface which is concentric with the outer surface of the concave mold and has a diameter of 2 to 12 mm in a circumferential contact. And a second means for exerting a pressing force in the direction of the mold, the mold assembly separating means.

According to the present invention, the shape of the second means having the function of coming into contact with and pushing up the outer surface of the concave surface is an annular shape, and the central portion and the outer portion of the annular shape are non-contact shapes. And The mold separating means of the conventional lens forming mold assembly is one in which one of the annular flanges existing around each mold is fixed and the other is applied with a peeling force in a direction in which the molds are separated from each other. In such a method, it was necessary to add special conditions such as heating one of the molds to generate a thermal gradient and separating the molds by the difference in the expansion degree. The reason for this is that in these lens manufacturing methods (mold polymerization method), in general, a solvent that does not participate in polymerization other than the monomer is added to the filling material in the mold space in consideration of the volume contraction due to the polymerization of the monomer. Is already in a flexible state, and it was necessary to operate it so as not to apply direct force to the lens forming part as much as possible, so that it was a condition to not damage or damage the finished lens. Is. That is, when the present invention is applied to the mold polymerization method using a conventional solvent, the flexible lens formed between the convex mold and the concave mold is compressed between the molds, and as a result, Since the lens causes cracks and distortions, the application of the present invention is difficult unless the lens material can withstand the cracks and distortions. Accordingly, a) an ophthalmic lens which is flexible in the case of (a) polymerization without addition of such a solvent (absorption of polymerization shrinkage due to the elastic force of the mold) and b) is flexible after polymerization regardless of addition of a solvent. Or c)
When manufacturing a lens by a single-sided cutting method in which one side is finished by cutting and the other side is finished by cutting (since it is not necessary to add a solvent that does not participate in polymerization to the monomer mixture by concentrating the polymerization shrinkage on the cutting side, The lens blank obtained in the assembly has a hard property after polymerization), and a method of applying a force from the outer surface of the concave mold of the present invention to perform mold separation can be adopted.

In the present invention, when a pressing force is applied from the outer surface of the concave mold, as described above, the outer surface of the concave mold is concentric and has a diameter of 2 to 12 mm (depending on the diameter of the outer surface of the concave mold). Apply force to contact and press in the direction of the convex surface. Basically, the monomer has been polymerized before opening the mold, and the mold can be separated regardless of where the force for pressing the concave mold is applied. However, when pressed against the center of the concave surface type, even an ophthalmic lens or a lens blank (hereinafter referred to as a lens material) shown in the above conditions has a considerable influence on the optical part thereof, and for example, a water-containing lens In this case, when the lens power is measured after water is hydrated, there is a high risk that the corona is not clear and the optical surface is affected. Therefore, it is not desirable to apply the pressing force to the center diameter within 2 mm, preferably within 4 mm. Also, the diameter is 12
If the size is more than mm, there is a problem that a large pressing force is required for the concave surface mold and the mold is damaged, or the lens material is stuck to the concave surface mold and cannot be separated.
It is necessary to make contact with a circle having a diameter of m or less, preferably 10 mm or less. The contact portion is basically an annular line contact, but may be a circumference having an appropriate width. However,
If the width of the contact area becomes too wide, the entire concave surface mold will be pressed uniformly, so the lens material and the concave surface mold will not separate easily, and it will be separated from the convex surface mold while being adhered to the concave surface mold, or a large pressing force is required. Therefore, the width of the contact surface (annular shape) is preferably 2 mm or less because the mold may be damaged and the lens material may be damaged in a severe case.

Further, it is desirable that the pressing contact portion of the present invention is such that a part of the annular shape is in a non-contact state. This is because the lens material is more likely to be peeled from the concave surface when the concave surface mold is subjected to a force (non-uniform force) that is distributed as much as possible to separate the mold with some deformation. In the conventional method, one mold is heated to provide a heat gradient between the lens and the mold to facilitate peeling, but in the present invention, the concave mold is pressed from the outside without the need for a special mechanism. It became possible to peel efficiently by adjusting the shape of the means. Of course, the lens material can be sufficiently peeled off just by pressing it in an annular shape, but if the lens material and the mold material are easily adhered to each other, the pressing force may be further dispersed to deform the mold. The lens material and the mold can be easily separated from each other. The structure in which a part of the annular shape is in non-contact means that one or more places on the circumference are not in contact with each other. Although it will be described later in detail, such as making contact with three arcs without contacting the place, it can be adjusted by a member provided with a notch in a part of the cylindrical pressing means.

The concave mold used in the present invention preferably has an annular flange on the periphery. This part serves as the point of action of the push pin for releasing the mold from the mold when molding the mold, and when forming the lens material mold assembly, the mold clamping structure for both molds is provided, and the mold assembly is separated. When it does, it functions as a part for fixing the mold by the first means. Further, it is not always necessary to have flanges on both molds, and the convex molds may not have flanges as long as both molds are fitted so as to retain a predetermined shape when assembled.

The lens material mold assembly of the present invention comprises a convex surface mold forming the inner surface side of the ophthalmic lens and a concave surface mold forming the outer surface side of the ophthalmic lens. When giving an optical curvature, a mold having a curved surface to be transferred is used as a mold on the target side. These molds are generally formed by injection molding or thermocompression molding, and the resin used for the mold is appropriately selected from, for example, polyethylene, polypropylene, ethylene vinyl acetate, propylene copolymer, polystyrene, nylon, etc. so that it is cheap and easy to handle. It is composed of a thermoplastic material. These are appropriately selected depending on the compatibility between the monomer mixture to be used and the mold material and whether they are obtained by thermal polymerization or photopolymerization such as ultraviolet ray.

The monomer mixture forming the lens material of the present invention may be any material as long as it exhibits the function of an optical lens and is not optically affected by the subsequent mold opening operation. Methyl (meth) acrylate,
Including alkyl (meth) acrylates such as ethyl (meth) acrylate, styrene monomers, silicon-containing monomers, fluorine-containing monomers, N-vinylpyrrolidone,
It is made of a material obtained by appropriately combining and polymerizing various general monomers used as a lens material such as dimethylacrylamide. In particular, in the present invention, a combination of monomers is preferable, which is a mold opening suitable for a manufacturing method (single-sided cutting method) in which an inner surface is formed by cutting and an outer surface is formed by cutting, and a water-containing material capable of being cut.

By using the apparatus having the mold separating means described above, when the lens material mold assembly is separated, the concave surface mold can be separated and removed while the lens material is always adhered to the convex surface mold. Is. That is, since the lens material is always adhered to one of the molds, the transition to post-processing is easy. For example, open the mold and transfer the mold with the lens material to the hydration process, or make marking such as laser mark,
Alternatively, the lens material is still attached to the mold and the outer surface is cut so as to have a desired lens power standard. Since the mold for shifting between these processes is always a convex mold, inspection at that time is unnecessary.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention (with respect to a single-sided cutting method) will be specifically described below with reference to the above contents with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of a lens blank mold assembly 1 in which a convex mold 2 that forms the inner surface of a contact lens and a concave mold 3 that forms the front surface of the lens to be processed in a later step are assembled. The lens is manufactured by a single-sided cutting method, and a space 4 formed between the convex mold 2 and the concave mold 3 is filled with a liquid monomer mixture which is a lens material selected from each monomer group, and is thermally polymerized. Or, it is polymerized and cured by photopolymerization with ultraviolet rays or the like. In FIG. 1, the inner surface of the lens is formed by transferring the convex surface 5 of the convex mold 2, and preferably the edge portion of the lens is also transferred and formed by the edge forming portion 6 formed in an annular shape around the convex surface 5 as shown in the figure. It This edge portion is also an effective shape when the lens blank is always left in one mold. The convex mold has an overall diameter of 17 mm, the convex surface 5 has a curvature of 5.5 mm, and the convex portion has a diameter of 9.0 mm, while the concave mold has an overall diameter of 17 mm, the concave portion 7 has a curvature of 6.0 mm, and the concave portion has a diameter of 9. It has a shape of 0.4 mm.

The convex mold 2 and the concave mold 3 are formed by injection molding of polystyrene resin, respectively.
The concave portion 7 was filled with 95 parts of hydroxyethyl methacrylate, 3 parts of methacrylic acid, 0.2 part of a cross-linking agent ethylene glycol dimethacrylate, and a monomer mixture of Darocur 1173 as a polymerization initiator. The monomer mixture is confined in and the mixture is transferred to the ultraviolet irradiation polymerization step. The convex mold 2 and the concave mold 3 have a portion 8 for clamping both molds on the outer periphery other than the lens forming surface. This part is not always necessary, but when the convex mold 2 is simply stacked, the monomer mixture may leak,
During handling of the mold assembly, the mold is likely to lose its shape, or air is apt to enter due to poor sealing, which may hinder the reaction during the polymerization of the monomer mixture. Therefore, it is desirable to form the portion 8 so that the two molds are fitted with each other with an appropriate force. The monomer mixture thus polymerized is then transferred to an apparatus having a mold separating means of the present invention to separate the concave mold 3.

2A and 2B show the separating step of the mold separating means. FIG. 2 (a) shows a first means 11 for fixing the concave mold 3. Therefore, this first means 1
The concave mold 3 must be provided with a portion that can be fixedly held by 1. This part is shown in the figure as a flange 9 extending around the mold 3. Even if there is no flange around the concave mold, form a thicker mold circumference, for example, the first means is a sharp needle-like one, so that it penetrates from the resin side of the mold material rather than the concave mold circumference. It may be fixed, or a groove may be formed on the peripheral side surface of the concave surface type, and a ring-shaped fixing means may be fitted into the groove. The first means is for fixing and holding the concave mold with respect to the second means 12 which is pushed up from below as shown in FIG. 2 (b). Generally, one having a flange around the concave mold is used. Can be fixed most stably.

FIG. 2B shows a step of separating the concave mold 3 by pushing it up from below the concave mold 3 by the second means 12. The second means 12 has an inner diameter of 7 mm and an outer diameter of 9 mm
The hollow cylinder is pressed from the outer surface of the concave mold 3, and when the inner surface end portion 13 of the cylinder is in an acute angle, when the pressing force is applied to the concave resin outer surface, it is prevented from penetrating into the resin. The corners of the end portion 13 are rounded so as to have a slight radius. The second means is the outer surface apex 1 of the concave mold 3.
Of course, the second means does not come into contact with 0 within a circle having a radius of 1 mm, preferably 2 mm from the apex. If it tries to contact and press the vicinity of the apex 10, it will leave stress and strain on the lens blank, which will affect the shape and power of the lens, and the corona on the power meter, for example, will not be clear (vision is completely corrected). It may not be possible). In addition, if a position of a circle with a radius of 4.6 mm or more is pressed from the apex, the distance between the first means and the second means becomes narrower and a considerably strong pressing force is required. It is desirable to press within a circle with a radius of 4.6 mm or less for reasons such as the fact that the inner surface and the lens blank remain adhered and become difficult to peel off. After all, for the concave mold of the present embodiment, the hollow cylindrical second means is used to make the diameter 2
It is preferable to apply a pressing force in a circumferential shape of 9.2 mm.
It should be noted that the end surface of the hollow cylinder may be shaped to match the outer surface curvature of the concave type so as to have a width in the circumferentially contacting portion, but it is processed in that way even though there is not much difference in the effect surface. This increases extra processing costs and seems to be meaningless.

3 (a), 3 (b) and 3 (c) show another end face shape of the second means. (B) is one in which non-contact portions are provided at two positions on the circumferential contact surface with respect to the concave surface type, (c)
Indicates that four non-contact parts are provided. By having these non-contact portions, the pressing force on the concave surface mold becomes slightly non-uniform, and the lens blank can be more easily peeled from the concave surface. By using the mold separating device having these first means and second means,
Since the lens blank can be separated into the concave mold while being always adhered to the convex mold 2, the convex mold should be transported to the outer surface processing machine uniformly, and the convex mold is fixed to the chuck of the processing machine. It can be used as a part to cut the outer surface.

In addition to the above examples, for example, a lens is manufactured by a mold polymerization method in which both convex and concave molds have a curvature for forming a lens, or a lens blank for double-sided processing of a curvature for forming a lens after polymerization in a mold. Method, the mold separating apparatus according to the present invention can be applied in the same manner as described above.

[0025]

As described above, by using the mold assembly separating apparatus having the first and second means of the present invention, the mold can be easily and always fixed to the mold while the ophthalmic lens or lens blank is bonded. Can be separated. The first and second means are simple and efficient mold separating means,
As described above, since the ophthalmic lens or the lens blank can be separated in a state of being adhered to a certain mold side, the lens can be put on a series of automatic production lines and the lens can be mass-produced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a mold assembly according to the present invention.

FIG. 2 is a view showing the action of the first means (a) and the second means (b) when opening the mold assembly according to the present invention.

FIG. 3 is a perspective view showing another example of the second means according to the present invention.

[Explanation of symbols]

1 Lens blank type assembly 2 convex type 3 concave type 4 Lens material 5 convex 6 Lens edge forming part 7 concave 8 Mold clamping area 9 flange 10 Concave type apex 11 First means 12 Second means

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tomio Nagao             Gifu Prefecture Gujo-gun Hachiman-cho Asahi character Shimizu Gen 15             Ceremony company Tomoe Gifu factory inside F-term (reference) 4F202 AA21 AH74 CA01 CB01 CK13                       CK53 CM11 CM21

Claims (4)

[Claims] 1. A mold assembly for polymerizing raw material monomers in a space substantially sealed between a convex mold and a concave mold to mold an ophthalmic lens or a lens blank having a size capable of giving an ophthalmic lens. (A) a first means for holding the concave mold of the mold assembly, and (b) a circumferential surface having a diameter of 2 to 12 mm, which is concentric with the outer surface of the concave mold and concentric with the mold. And second means for exerting a pressing force in the direction of the convex mold. 2. The mold assembly separating means according to claim 1, wherein the concave mold has a flange on its periphery, and the flange is held by the first means. 3. The mold assembly separating means according to claim 1, wherein a part of the circumferential contact surface of the second means is in a non-contact state. 4. A method for separating a mold using an apparatus having the mold assembly separating means according to any one of claims 1 to 3, always leaving an ophthalmic lens or a lens blank in a convex mold.