JP3749632B2 - Mold for contact lens molding - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a mold for producing a contact lens. More specifically, the present invention relates to a mold that eliminates the need for secondary processing on the periphery of the contact lens.
[0002]
[Prior art]
Current methods for manufacturing contact lenses include a lace cut method that uses a cutting machine, a cast mold method that uses a mold, and the like. The lace-cut method, which is a common contact lens manufacturing method, can arbitrarily manufacture a wide variety of contact lenses with different parameters, but has a problem of high manufacturing cost due to the large number of steps.
[0003]
In order to solve the disadvantages in manufacturing costs of these race-cut manufacturing methods, in the cast mold manufacturing method, contact lens raw materials (hereinafter referred to as lens raw materials) are injected into a mold corresponding to each parameter of the contact lens and then heated or irradiated with ultraviolet rays. Mold. This method has the advantage that mass production is possible at low cost, but it is necessary to prepare a mold according to each parameter such as the refractive power of the wearer and the lens size. It is not suitable for manufacturing various types of contact lenses.
[0004]
As an important part in designing a mold in the cast mold manufacturing method, there is a contact part of both molds when the male mold and the female mold are combined. The reason for this is that burrs, etc. that occur at the contact parts of both molds not only reduce the production efficiency, but also the edges of the contact lens, which greatly affects the feeling of wearing that is important when wearing contact lenses. ing.
[0005]
In the contact lens mold currently used, the edge of the edge part is the contact part of the male and female molds, and most of the sharp edges are not rounded. Compared with the rounded edge part of the race-cut manufacturing method Then, it was not satisfied with a feeling of wearing.
[0006]
In the conventional contact lens mold, the contact portions of both molds when combined are so-called line contact in which one mold is in contact with a line while the other mold is in contact with a point. For example, as shown in FIG. 4, the contact portion when combining both types disclosed in Japanese Patent Application Laid-Open No. 2-270517 includes a female taper portion (25) and a male right angle or obtuse angle portion (27). This is a combination of line contact and is greatly different from the rounded edge shape required for contact lenses.
[0007]
In Japanese Patent Publication No. 6-20761, the male lens (78) shown in FIG. 5 and the female lens (75) are rounded, and the edge shape is rounded. In particular, the portion indicated by the reference numeral (79) in the male type and the female type has a line contact shape.
[0008]
On the other hand, various studies have been made on the processing method of overflowing lens raw materials. The most common processing method is to perform the processing after contact lens molding. The most common treatment method is to apply a shape to either the male or female mold and attach the overflowed lens raw material to either the male or female mold when releasing. . As an example, in Japanese Patent Publication No. 6-20761, a groove (65) shown in FIG. 5 is provided in the male mold to increase the contact area of the overflowed lens raw material, thereby forming the grooved lens raw material overflowed at the time of release. JP-A-7-68573 discloses a method of attaching to a mold, and a method of removing a lens raw material (38) overflowing at the time of mold release from a contact lens by attaching a protrusion (39) as shown in FIG. is doing. Similarly, in Japanese Patent Laid-Open No. 10-309728, the shape of the mold is changed by laser or discharge treatment of the portion (50) shown in FIG. 7 in order to adhere the lens raw material overflowing the mold.
[0009]
[Problems to be solved by the invention]
A disadvantage of the conventional combination of male and female line contact is that adhesion is weak. When molding with a combination mold having weak adhesion, fatal defects such as burrs and burrs are generated in the molded contact lens. In order to increase the adhesion, when using a thermoplastic resin that is generally used for a contact lens mold, dimensional accuracy during injection molding is an important factor. In particular, when a crystalline resin such as polypropylene or polyethylene is used, it is difficult to injection mold a fine shape required for combining both molds because of large molding shrinkage. That is, it is extremely difficult to uniformly form the acute shape shown by reference numeral (79) in FIG. 5 over the entire circumference of the mold.
[0010]
In addition, when the shape is such an acute angle, the contact portion at the time of combination of the molds may be deformed due to polymerization shrinkage, or the contact position may move, and a desired edge shape may not be obtained. .
[0011]
On the other hand, the overflow lens raw material is generally treated by attaching the overflowed lens raw material to a designated mold after forming the contact lens. However, these methods do not remove excess lens raw material that has overflowed, so that the overflowed lens raw material may remain attached to the contact lens after molding in some form.
[0012]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, in the present invention, the cross-sectional shape when combining both molds is such that the direction of the curved portion of the female mold on the lens cavity side and the curved portion of the outer female mold is as shown in FIG. The contact area when combining male dies can be increased by using different shapes, that is, S-shaped, and higher adhesion can be obtained when combining both dies than simple line contact. .
[0013]
Further, the portion corresponding to the front side edge and the rear side edge of the contact lens shown in FIG. 3 are rounded and thick, so that the molding die is not deformed by polymerization shrinkage, and the molding die is moved by polymerization shrinkage. Since the direction can be moved only in the direction in which the male mold and the female mold are in close contact with each other, a more ideal rounded edge portion of the contact lens can be formed.
[0014]
Further, the overflowing lens raw material is not removed after molding of the contact lens, but all the excess lens raw material overflowing is removed at the monomer stage before molding. That is, in the method of removing the lens raw material overflowed before molding the contact lens, the monomer reservoir is provided obliquely with respect to the axial direction of the mold between the male mold and the female mold which are the molds of the present invention, and the male mold According to the shape of the resin mold in which a groove along the axial direction is provided between the outer side surface portion and the inner side surface portion of the female mold, this can be easily performed.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a cross-sectional view of a preferred embodiment of the contact lens molding die of the present invention, and FIG. 2 shows another preferred embodiment of the combination of the contact lens molding die of the present invention. FIG. 3 is an enlarged cross-sectional view of the main part in a combined state of the contact lens molding die of the present invention.
[0016]
In the figure, 1 is a female mold, and in the figure, 2 is a male mold. The female mold 1 and the male mold 2 are combined, and a lens cavity 4 is formed between the female mold 1 and the male mold 2 by the contact portion 3 corresponding to the edge portion of the contact lens. A monomer reservoir 5 is formed outside the contact portion 3.
[0017]
As shown in an enlarged view in FIG. 3, the curved portion 11 of the female mold 1 corresponding to the edge portion of the lens on the lens cavity 4 side and the curved portion 13 outside the female mold 1 that follows the curved portion 11 are curved. Are formed in different shapes. That is, as shown in an enlarged view in FIG. 3, the curved portion 11 of the female mold 1 corresponding to the edge portion of the lens in the cross-sectional shape is formed in a depressed shape, and from the lens cavity 4 continuous therewith. The outer curved portion 13 is formed in a bulging shape, and a rising portion 12 that rises substantially perpendicularly is formed at the boundary portion.
[0018]
On the other hand, the male edge portion 21 corresponding to the lens edge portion of the lens cavity 4 in the cross-sectional shape is formed in a recessed shape, and the side surface portion 23 continuous to the tip portion 22 is formed in a substantially vertical shape. It is.
[0019]
Due to the shape of the contact part 3 between the female mold 1 and the male mold 2, the tip 22 of the edge part 21 of the male mold 2 is continuous with the curved part 11 corresponding to the edge part of the lens of the female mold 1. The gap between the monomer reservoirs 5 located above the contact position becomes extremely narrow in the state of contact with the rising portion 12.
[0020]
By narrowing the gap of the monomer reservoir 5 at the curved portion 13 on the outer side of the female die 1, the side surface portion 23 immediately above the tip portion 22 of the edge portion 21 of the male die 2 is substantially near the rising portion 12 of the female die 1. Will come into contact. As a result, the contact portion in the combination of the conventionally known molds shown in FIGS. 4 and 5 contacts only at one point according to the sectional view, whereas the contact portion in the combination of the present invention is curved on the outer female mold. Since the portion 13 and the rising portion 12 are in contact with each other on the surface, higher adhesion is obtained.
[0021]
Even when the lens raw material shrinks at the time of polymerization, since no acute angle portion is formed at the contact portion of the mold, both molds have a strong shape that can sufficiently withstand the polymerization shrinkage. Furthermore, in the mold of the present invention, the movement direction of the male mold 2 and the female mold 1 due to polymerization shrinkage is only the movement of the mold in the axial direction. The curved portion 13 on the outer side of the female mold 1 has a continuous and smooth curve between the rising portion 12 and the curved portion 13 that bulges from the curved portion 11 that is recessed near the contact portion 3 with the male mold 2. In order to reduce the width of the male mold 2, it also serves to prevent lateral movement with respect to the axis of the male mold 2. Since the movement in the vertical direction with respect to the axis of the male mold 2 is a direction in which the contact portion at the time of combination approaches the position of the curved portion 11 of the female mold 1 on the lens cavity 4 side, the edge portion of the contact lens after polymerization is Depending on the shape of the mold, it can always have a good rounded shape.
[0022]
As a method of removing the overflowing lens raw material, the monomer reservoir 5 shown in FIGS. 1 and 2 is provided obliquely with respect to the mold shaft 10 and is removed by air blowing or the like from the oblique upper portion thereof. it can. In addition, when a highly volatile lens raw material is used, the removal of excess raw material can be accelerated by providing the monomer reservoir 5 at an angle.
[0023]
FIG. 2 shows an embodiment in which a groove 15 is formed between the side surfaces of the female mold 1 and the male mold 2. This groove 15 communicates with the monomer reservoir 5, and when removing the excess lens raw material overflowed by air blow, it improves air passage and facilitates removal of the excess lens raw material overflowed.
[0024]
In ultraviolet polymerization, it is important to irradiate the lens cavity 4 with uniform ultraviolet energy. In order to irradiate the lens cavity 4 with uniform energy, the accuracy of the ultraviolet irradiation device is required, but the female mold 1 and the male mold 2 forming the lens cavity 4 are made to have the same wall pressure as much as possible. Things are necessary. In order to irradiate ultraviolet energy more efficiently, it is effective to irradiate ultraviolet rays from both the upper and lower directions of the combined mold. By irradiating ultraviolet rays from above and below, it is possible to significantly shorten the molding time and to mold a contact lens with extremely little polymerization distortion.
[0025]
Therefore, it is effective to remove as much as possible an obstacle in the lens cavity 4 in order to make it easy to irradiate ultraviolet rays from both the upper and lower surfaces. For example, if the monomer reservoir 5 is attached in the arrangement as shown in FIG. 1, it is difficult for ultraviolet energy from the male mold direction to enter, and as a result, the polymerization at the lens edge portion does not proceed easily. Therefore, as shown in FIG. 2, by taking the monomer reservoir 5 a certain distance from the edge portion of the lens cavity 4 to the outside, the outer width of the lens cavity 4 of the male mold 2 can be taken. 4 can be efficiently irradiated with ultraviolet rays. The arrangement of the monomer reservoir 5 makes it possible to uniformly irradiate ultraviolet rays, and to form a shape suitable for a mold for double-sided irradiation.
Of course, the shape of this mold is also effective for thermal polymerization and single-sided ultraviolet polymerization.
[0026]
The material of the mold of the present invention is very effective for thermoplastic resins, more specifically, crystalline resins such as polypropylene, polyethylene, polyacetal, etc., but other resins and materials other than resins such as glass, It can also be applied to metals.
As a contact lens raw material, any of 2-hydroxyethyl methacrylate, N-vinyl pyrrolidone, vinyl acetate, methyl methacrylate, methacrylic acid, fluorine-containing monomer, siloxane-containing monomer and the like can be used.
[0027]
[Example 1]
Polypropylene having the shape shown in FIG. 1 having a curvature radius designed with a base curve and a front curve in consideration of the swelling rate, and a uniform thickness of 1.0 mm for both the male mold 2 and female mold 1 of the lens cavity 4 part. Using a mold, a 0.1% highly volatile lens raw material is dispensed into the female mold 1 on the front curve side. Thereafter, the male mold 2 on the base curve side was combined with the female mold 1 and allowed to stand to completely evaporate excess lens raw material overflowed from the monomer reservoir 5, and then thermal polymerization was performed. After completion of the polymerization, the lens is released from the mold and subjected to swelling treatment. The obtained contact lens was free from burrs, burrs, sink marks and the like and had a good edge.
[0028]
[Example 2]
Polypropylene having the shape shown in FIG. 2 having a radius of curvature designed with a base curve and a front curve in consideration of the swelling rate, and a uniform thickness of 1.5 mm for both male mold 2 and female mold 1 in the lens cavity 4 part. Using a manufactured mold, 0.1 mg of the lens raw material is dispensed into the female mold 1 on the front curve side. Then, after the male mold 2 on the base curve side is combined with the female mold 1, air blow is performed toward the vertical groove 15 provided in the female mold 1, and the excess lens raw material overflowing the monomer reservoir 5 is completely removed. After removal, UV polymerization was performed. After completion of the polymerization, the lens is released from the mold and subjected to swelling treatment. The obtained contact lens was free from burrs, burrs, sink marks and the like and had a good edge.
[0029]
【The invention's effect】
Since the mold of the present invention has a structure with high adhesion when combined, it is possible to produce a contact lens having a smooth edge shape without the occurrence of burrs, chips and sink marks in the mold.
In addition, by using this mold having high adhesion, it is possible to mold a contact lens free from bubbles, scratches, sink marks, striae, etc., even when using a lens raw material that is highly volatile and difficult to polymerize. it can.
Further, since all the excess lens raw material overflowed before the contact lens molding can be easily removed, the work process after the lens release is simplified. The groove on the side surface of the mold provided to remove excess lens raw material also has an effect of preventing bubbles from entering the lens cavity when the lens raw material is dispensed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an embodiment of a contact lens molding die of the present invention. FIG. 2 is a cross-sectional view of another embodiment of a contact lens molding die of the present invention. FIG. 4 is a cross-sectional view of an edge portion in an example of a conventional mold. FIG. 5 is a cross-sectional view of an edge portion in another example of the conventional mold. FIG. 7 is a cross-sectional view of removing excess overflowing lens raw material in a conventional mold. FIG. 7 is a cross-sectional view of removing overflowing excess lens raw material in another conventional mold.
DESCRIPTION OF SYMBOLS 1 Female type | mold 2 Male type | mold 3 Contact part 4 Lens cavity 5 Monomer reservoir 11 Curved part 12 Standing part 13 Curved part 21 Edge part 22 Tip part 23 Side part

Claims (3)

In a mold composed of a male mold having a convex part and a female mold having a concave part, the curved part of the female mold on the lens cavity side and the curved part of the female mold outside the lens cavity at the contact part when the two molds are combined Molding mold for contact lens molding, in which the curved direction of the part is formed in different shapes, and the contact part of both molds in the combined state of both molds is surface contact, and the adhesion of the contact parts of both molds can be improved   In a state where both molds are combined, a monomer reservoir is provided on the outside of the lens cavity obliquely with respect to the axial direction of the mold, and a groove along the axial direction is arranged between the male outer surface and the female inner surface. The contact lens molding die according to claim 1, wherein the contact lens molding die is provided.   3. The molding for forming a contact lens according to claim 1, wherein the thicknesses of the male mold and the female mold are the same in order to make the thickness of the mold for molding the lens cavity portion uniform. Type.

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