JPS61290012A - Lens molding device - Google Patents

Abstract

PURPOSE:To contrive to improve productivity and yield of high accuracy lens, by forming a space for adjusting the quantity of lens manufacturing material connected through a fine gap with a lens forming space formed when a male die and a female die are put together. CONSTITUTION:The shape of the lens forming space 17 formed by a projection 15 and a cavity 12 when a male die 14 and a female die 11 are put together, is designed to the same shape as that of the lens to be prepared. A space 18 for adjusting the quantity of lens manufacturing material formed by a collar part 16 of the male die and a step part 13 of the female die is connected with the lens forming space 17 through a very fine gap 19. To prepare a contact lens, for example, by using the lens molding device thus constituted, an excessive amount of a polymerizable monomer is poured in the cavity 12 of the cavity part 11 and the male die is then put together with the female die. The excess part of the polymerizable monomer is pushed out of the cavity 12 to the space 18 for adjusting the quantity of lens manufacturing material through the gap 19 and the monomer is then subjected to the pressurizing and heating.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lens molding device such as a contact lens mold.

[Prior art and its problems]

FIG. 3 is an explanatory cross-sectional view of a conventional contact lens mold.

In the figure, 1 is a male part of the contact lens mold, 2 is a female part of the contact lens mold, and 3 is formed when the male part 1 and the female part 2 are matched. This lens forming space 3 is designed to have a predetermined shape.

In order to mold a contact lens using such a contact lens mold, a certain amount of accurately measured lens material is injected and filled into the female mold part 2, and then the male mold part 1 is inserted into the female mold part 2. Contact lenses are obtained by matching and curing the materials.

However, when a contact lens mold as described above is used to obtain a contact lens, the amount of lens material injected into the female mold part 2 must not be too small;
On the other hand, if there is too much, it will be extremely difficult to measure the amount to be injected and filled due to the formation of flakes on the periphery, resulting in disadvantages such as poor working efficiency and poor manufacturing yield.

Furthermore, since volumetric shrinkage usually occurs during polymerization and curing, measuring the amount of lens material to be injected becomes even more difficult. Even if this is done, the shape may differ from the desired shape due to volumetric shrinkage that occurs during polymerization and curing, and for example, the base curve may be distorted, resulting in the drawback that the power of the lens will not match the designed value.

[Means for solving problems]

The present invention has been made in view of the apex of the above,
It is composed of a male mold part and a female mold part, and is configured such that a lens forming space is formed when the male mold part and the female mold part are matched, and further the male mold part and the female mold part are matched. The present invention provides a lens molding apparatus configured such that a lens material amount adjustment space connected to the lens forming space via a minute gap is formed when the lens forming space is formed.

〔Example〕

FIG. 1 is an explanatory cross-sectional view of one embodiment of the lens molding apparatus according to the present invention, and FIG. b) is an explanatory cross-sectional view of the lens obtained through the process of FIG. 2(a).

In the same figure, 11 is a substantially dome-shaped four part 12, and this four part 1
20 is a female mold part including a step part 13 formed to extend along the peripheral end part.

Reference numeral 14 denotes a male part including a substantially dome-shaped protrusion 15 provided corresponding to the four parts 12, and a flange 16 formed to extend from the base of the protrusion 15.

17 is a lens forming space formed by the convex part 15 and the concave part 12 when the male mold part 14 is fitted into the female mold part 11, and the shape of this lens forming space 17 is the shape of the intended lens. It is designed to have the same shape as the

Reference numeral 18 designates a space for adjusting the amount of lens material formed by the flange portion 16 and the step portion 13 when the male mold portion 14 is fitted into the female mold portion 11; The space 18 and the lens forming space 17 are connected through an extremely fine gap 19 (this gap is located at a position corresponding to the peripheral edge of the lens).

In order to mold, for example, a contact lens using the lens molding apparatus configured as described above, the four parts 1 of the female mold part 11 are
2, a polymerizable monomer such as 2- and droxyethyl methacrylate, methyl methacrylate, and N-vinylpyrrolidone is injected in excess of the volume of the lens forming space 17;
Thereafter, the male mold part 14 is matched with the female mold part 11, and the excess polymerizable monomer in the lens forming space 17 is released into the lens material amount adjustment space 18 through the gap 19, and then the male mold part 14
The polymerizable monomer is polymerized and hardened by heating with a predetermined pressure applied to the female mold part 11 and the female mold part 11, and then the female mold part 11 is separated from the male mold part 14, and then the mold part 11 is separated from the male mold part 14, and then, for example, with a bottle set or the like, as shown in FIG. Grip the peripheral flange 31 of the molded product 30 shown in FIG. 2(a), peel it off from the female mold part 11 and take it out, and then remove the peripheral flange 31 to form the molded product 30 as shown in FIG. 2(b). A contact lens 32 is obtained.

In the above contact lens manufacturing process, the female mold part 11
The amount of the raw material polymerizable monomer to be injected and filled into the recess 12 may be larger than the volume of the lens forming space 170. Since the strict condition that the amount of monomer must be extremely accurately determined is relaxed, the workability is further improved. If it is a strip, there will be no distortion in the resulting molded product, and contact lenses can be obtained with a high manufacturing yield.

In particular, even if a volumetric contraction phenomenon occurs during polymerization of the polymerizable monomer, the negative pressure of this volumetric contraction causes the polymerizable monomer existing in the lens material amount adjustment space 18 to flow into the lens forming space 17 through the gap 19 and be replenished. Therefore, the shape of the contact lens obtained is the shape of the lens forming space 17 itself, and a highly accurate contact lens that follows the desired base curve can be obtained.

Moreover, after polymerization and curing of the polymerizable monomer, the molded product 30
When peeling off from the female mold part 11, the peripheral flange part 31 can be grasped and peeled off with tweezers or the like, so that the contact lens 32 can be peeled off from the female mold part 11 without damaging the optical part of the contact lens 32 at all.

Incidentally, since the boundary between the contact lens 32 and the peripheral flange 31 in the molded product 30 is extremely thin, the peripheral flange 31 can be removed by simple cutting means.

Although not specifically mentioned as the constituent materials of the female part and the male part in the above embodiments, for example, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, polyethylene, fluororesin,
Plastics such as polyamide, polyimide, polyacecool, etc., or metals such as ferrous metal materials such as brass, Sterisis, SKD or SKS can be used.

〔effect〕

Since the present invention is configured as described above, there is no need to accurately measure the amount of the injected light #A of the lens material.In other words, it is sufficient to fill the lens material with an amount larger than the volume of the lens forming space. The workability is further improved, and if a large amount is injected and filled in this way, even if volume shrinkage occurs during curing, a corresponding amount will be present in the space for adjusting the amount of lens material. The lens material flowing into the lens forming space is replenished,
Therefore, the incidence of defective products such as those caused by deviations in the base curve is reduced, and the molded product can be peeled off without damaging the optical part of the lens, increasing the efficiency of manufacturing high-precision lenses. It also has the advantage of being able to provide high manufacturing yields.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional explanatory diagram of one embodiment of the lens molding apparatus according to the present invention, FIGS. 2(a) and (b') are explanatory diagrams of a molded product obtained using this lens molding apparatus, and FIG. FIG. 1 is an explanatory diagram of a conventional lens molding apparatus. 11-female part, 12... recessed part, 13... stepped part, 14
...male part, 15... convex part, 16... flange part, 17
°...Lens formation space, 18...Space for lens rate meter adjustment, 19...Gap.

Claims (1)

[Claims] It is composed of a male mold part and a female mold part, and is configured such that a lens forming space is formed when the male mold part and the female mold part are matched, and further the male mold part and the female mold part are matched. 1. A lens molding apparatus characterized in that when the lens molding is performed, a lens material amount adjustment space is formed which is connected to the lens forming space through a minute gap.