JPH0544330B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mold used when manufacturing contact lenses by a cast polymerization method.

[Prior Art] Conventionally, contact lenses have been mainly manufactured by subjecting a material made of a polymeric composition having desired physical properties to mechanical processing such as cutting and polishing (hereinafter referred to as cutting and polishing method). With the cutting and polishing method, a contact lens having relatively good optical performance can be obtained, and its shape can be designed relatively freely as necessary.

In addition, as another method for manufacturing contact lenses,
There is a method called a spin cast method in which a polymerizable liquid is solidified on a rotating mold to obtain a contact lens. The spin-casting method involves carefully controlling a number of factors such as the viscosity, surface tension, and amount of the polymerizable liquid, the shape of the mold, the number of rotations, and the surface condition, etc., to form the desired contact lens. It is expected to improve productivity compared to , and is advantageous for manufacturing thin contact lenses.

Furthermore, a cast polymerization method is known as another method for manufacturing contact lenses. This method is a manufacturing method in which a polymerizable liquid is polymerized and solidified in a mold with a predetermined optical surface to form a contact lens shape, and has the advantage of high productivity and little variation in quality. .

[Problems to be solved by the invention] However, as is well known, the cutting and polishing method is a method in which each lens is cut out from a material one by one and finished by polishing, which inevitably requires a large number of manufacturing steps. Not only that, but it also required advanced machining techniques by skilled workers, which led to problems such as poor productivity. Furthermore, in the cutting and polishing method, the first condition is that the material is hard and can be machined, so even if the material has excellent physical properties, if there are problems with machinability or polishability, It had the disadvantage that it could not be made into contact lenses.

On the other hand, the spin-casting method requires advanced technology because it requires strict control of a large number of factors as described above, and the materials to which it can be applied are also limited to specific materials. In addition, the concave surface of a contact lens obtained by the spin-cast method is an aspherical surface with an almost parabolic shape, making it impossible to obtain a true optical surface. It has the disadvantage that it is difficult to set. Additionally, lenses obtained by spin-casting typically have the disadvantage of requiring final finishing around the lens after polymerization.

The cast polymerization method is effective as a means to solve the above-mentioned problems in the cutting and polishing method and the spin-casting method. However, the cast polymerization method involves the problem of volume shrinkage called polymerization shrinkage that occurs when a polymerizable liquid is polymerized and solidified. The volume shrinkage due to polymerization shrinkage of many monomers is in the range of 12% to 22%, and this shrinkage is in the range of 12% to 22%. This has been a major hindrance to the cast polymerization of contact lenses from vinyl monomers such as amides. In other words, when a contact lens is cast in a sealed mold, voids called sink marks may occur on the surface of the lens due to polymerization shrinkage, or cavities called voids may be formed inside the lens, causing the cast product to become a contact lens. Makes it unsuitable as a lens.

In order to solve these problems with cast polymerization, various methods have been proposed so far. For example, according to the method disclosed in Japanese Patent Application Laid-Open No. 52-117647, a flexible rim part is integrally placed in one of a set of molds, and polymerization shrinkage is caused by the curvature of the flexible rim part and the resulting thickness. Absorb by decreasing thickness. However, such flexible rim components must be thin to obtain sufficient curvature to absorb polymerization shrinkage;
Furthermore, since the tip must be sharpened to about 0.04 m/m to 0.01 m/m, there is a problem in handling that it is easily damaged even by slight contact. In addition, since the flexible rim parts described above directly form the outer periphery of the contact lens during cast polymerization, the design around the lens is limited to the shape obtained by the curvature of the rim, making it impossible to design freely. It had the following problems. In addition, since the flexible rim component must be integrated with the mold, the material that can be used as the mold is inevitably limited to plastic, which poses a major restriction in selecting the material for the mold. Furthermore, the material is limited to materials that do not dissolve or change in quality in the polymer composition solution used. Furthermore, the flexibility of the rim necessarily limits the hardness and heat resistance of the material that can be used as a mold, so deformation occurs during polymerization that requires heating, resulting in insufficient optical performance. The problem was that accurate accuracy could not be obtained.

Further, for example, according to the method disclosed in Japanese Patent Application Laid-Open No. 54-43269, a swollen soft contact lens can be manufactured by polymerizing and solidifying a polymerizable liquid together with a solvent in a mold. However, since this method is an application of a polymerization method using a solvent (solution polymerization method) to the production of soft contact lenses, it cannot be applied to cast polymerization of non-aqueous hard contact lenses.

The present invention was made for the purpose of solving the problems in the method for manufacturing contact lenses as described above, and more specifically, it solves the problems in the method for manufacturing contact lenses by cast polymerization, and provides a method for producing contact lenses of excellent quality. Contact lenses made extremely easy,
It was designed to be manufactured in a short period of time.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a molding part common to the main axis of both molding members on the outer periphery of the molding part between the male molding member and the female molding member. A ring-shaped spacer is interposed to form a contact lens mold.

Hereinafter, the configuration of the present invention will be explained in detail with reference to the drawings. FIG. 1 is an explanatory diagram for explaining the structure of the present invention, and FIG. 2 is a sectional view showing a state in which a contact lens mold according to the present invention is connected.

The invention comprises a first molding part 2 having a main axis for assembly in the vertical direction and comprising a first optical molding surface 1 for forming the first surface of a contact lens;
a male molding member 4 having a contact portion 3 with a spacer 9 at a position independent of the first molding portion 2; having a common main axis with the male molding member 4 and forming the second surface of the contact lens; a second molding part 6 that includes a second optical molding surface 5; and a female molding member 8 having a contact part 7 with a spacer 9 at a position independent of the second molding part 6; It is composed of a ring-shaped spacer 9 disposed at the center; and a liquid reservoir 6a provided in the shape of an inclined surface around the insertion portion of the female molded member 4. This liquid reservoir 6a can store excess polymer composition, and even if the amount of polymer composition liquid is not poured into the mold accurately, the polymer composition liquid will not contact and adhere to the spacer or attack the spacer. do not have.

The materials of the male molded member 4 and the female molded member 8 disclosed in the present invention include glass, metal,
Materials commonly used as mold materials, such as ceramics and plastics, can be applied.
In particular, when selecting a thermoplastic as a mold material, it is important to select a material with a heat distortion temperature that is 20 to 40 degrees Celsius higher than the polymerization temperature.
By applying ordinary plastic molding methods such as injection molding, injection compression molding, or compression molding to the materials selected in this way, it is possible to manufacture highly precise molded parts with extremely high productivity. It has its advantages. Examples of such thermoplastics include high density polyethylene, polypropylene, polytetrafluoroethylene, polychlorotrifluoroethylene, polyolefin copolymers, polyacetals, polyphenylene oxides, polysulfones, polyamides, and the like.

Further, as the material for the spacer according to the present invention, thermoplastic plastics or rubber elastic bodies having good flexibility near the polymerization temperature can be used. Examples of such materials include low density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, soft vinyl chloride, ionomer resin, urethane rubber, natural rubber, isoprene rubber, butadiene rubber, styrene- Examples include butadiene rubber, chloroprene rubber, nitrile rubber, silicone rubber, and acrylic rubber. These materials are
It is used after being molded into a predetermined shape using a normal molding method.

The male shown in the present invention is the first part of the molded member 4.
The optical molding surface 1 and the second optical molding surface 5 of the female molding member 8 are combined to form a meniscus-shaped contact lens, so that when the first optical molding surface 1 is substantially convex, the second optical molding surface 1 is substantially convex. The optical shaping surface 5 should be substantially concave, and when the first optical shaping surface 1 is substantially concave, the second optical shaping surface 5 should be substantially convex; Any combination is within the scope of the present invention.

Further, the first optical molding surface 1 and the second optical molding surface 5 of the male and female molding members 4 and 8 according to the present invention can be fully adapted to a contact lens designed by a combination of spherical surfaces, but if necessary, one can be used. Alternatively, the present invention is not limited in any way to a design in which both surfaces are made of aspherical surfaces.

Furthermore, the mold of the present invention does not preclude use by applying a load on the combined mold as the case requires.

[Function] In the contact lens mold according to the present invention, the male molding member 4 and the female molding member 8 are assembled along the main axis with a spacer 9 interposed between them.
At that time, the first molding part 2 of the male molding member 4 and the second molding part 6 of the female molding member 8 form a vertically movable fitting structure, and the contact lens molding is isolated from the outside. Create a void. When the molded members 4 and 8 are in complete contact with each other via the spacer 9, this gap provides a capacity corresponding to the predetermined shape of the contact lens.

The amount of the polymerized composition liquid that will be polymerized and solidified to form a contact lens is slightly larger to account for the volume of the contact lens to be molded into the second molding section 6 of the female molding member 8, as well as the amount of polymerization shrinkage and overflow. It is dripped with Thereafter, the spacer 9 is placed on the spacer contact portion of the second molded member, and the male molded member 4 is placed on the female molded member 8 along the main axis and moved downward. At this time, the excess polymer composition liquid is gradually removed from the molding space as the male molding member 4 moves, and is held by the liquid reservoir 6a so as not to contact the spacer 9. When both the molding members 4 and 8 are brought into complete contact with each other via the spacer 9, a certain volume of the polymeric composition liquid fills the gap for contact lens molding. At this time, the void for contact lens molding filled with the polymeric composition liquid is blocked from the outside by the first molding section 2 and the second molding section 6, as described above, and the air in the polymerizable liquid is There is no contact with By heating the mold filled with the polymerizable liquid in this manner in a constant temperature bath according to a predetermined temperature increase program, a desired contact lens can finally be formed.

When the polymerization composition liquid starts polymerizing in the heating process, its volume decreases due to polymerization contraction, and at this time, the polymerization composition liquid starts to polymerize on the first optical forming surface 1.
and the second optical forming surface 5, and as a result, a force is exerted in a direction that brings both optical surfaces closer to each other. Spacer 9 according to the invention
exhibits sufficient flexibility during the polymerization process, thereby reducing its thickness as the molded members 4 and 8 approach each other, and absorbing polymerization shrinkage in the thickness direction of the lens.

The above polymer composition liquid is made by adding appropriate amounts of a polyfunctional crosslinking agent and a polymerization initiator to a monomer or prepolymer having a single composition or a multicomponent composition. The monomers used here include the following.

(a) Methyl methacrylate, ethyl methacrylate,
n-butyl methacrylate, iso- methacrylate
Hydrophobic methacrylic acid substituted monomers such as butyl, tert.-butyl methacrylate, n-propyl methacrylate, iso-propyl methacrylate, uralyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, methylbenzyl methacrylate, isobornyl methacrylate.

(b) Methyl acrylate, ethyl acrylate, n-butyl acrylate, iso-butyl acrylate,
Hydrophobic acrylic acid substituted monomers such as tert.-butyl acrylate, n-propyl acrylate, iso-propyl acrylate, cyclohexyl acrylate, benzyl acrylate.

(c) Methacrylic acid-substituted monomers containing silicon, such as trimethylsilyl methacrylate, trimethylsilyl methyl methacrylate, and tris-trimethylsiloxysilyl-propyl methacrylate.

(d) Silicon-containing acrylic acid-substituted monomers such as trimethylsilyl acrylate, trimethylsilylmethyl acrylate, and tris-trimethylsiloxysilyl-propyl acrylate.

(e) 2-hydroxyethyl methacrylate, 2-
Hydrophilic methacrylic acid substituted monomers such as hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, glyceryl methacrylate, glycidyl methacrylate, methacrylic acid.

(F) Hydrophilic acrylic acid-substituted monomers such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, glyceryl acrylate, glycidyl acrylate, and acrylic acid.

(g) N such as N-methylacrylamide, N,N-dimethylacrylamide, N-methylmethacrylamide, N,N-dimethylmethacrylamide, etc.
- Hydrophilic monomers such as alkyl-substituted acrylamides or N-alkyl-substituted methacrylamides.

(h) Alkyl-substituted N-vinylpyrrolidone such as N-vinylpyrrolidone and methyl-substituted N-vinylpyrrolidone.

In addition, examples of polyfunctional crosslinking agents include ethylene glycol dimethacrylate, diethylene glycol dimectarylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol dimectarylate, trimethylolpropane trimethacrylate, vinyl methacrylate, allyl methacrylate, triethylene glycol dimethacrylate, Examples include allyl isocyanurate, vinyl acrylate, divinylbenzene, etc. Furthermore, as polymerization initiators, azobisisobutyronitrile, azobisdimethylvaleronitrile, benzoyl peroxide, di-tert.-butyl peroxide, lauroyl peroxide, etc. used.

[Examples] Hereinafter, the present invention will be explained in more detail based on Examples.

Embodiment 1 FIG. 1 is a partially cutaway exploded perspective view showing an embodiment of the present invention, and FIG. 2 is a cutaway front view of the embodiment shown in FIG. In this embodiment, the male molded member 4 and the female molded member 8 are manufactured by injection molding polypropylene, and the spacer 9 is manufactured by injection molding ethylene-ethyl acrylate copolymer. Male molded member 4
The first molding part 2 has a cylindrical shape with a diameter of 8.5 mm and has a first optical molding surface 1 with a radius of curvature of 8.00±0.01 mm at the tip. The second molding part 6 of the female molding member 8 has a cylindrical shape with an inner diameter of 8.5 mm and has a second optical molding surface 5 with a radius of curvature of 8.47±0.01 mm at the bottom, and does not allow excess polymeric composition liquid to come into contact with the spacer 9. It has a liquid reservoir 6a for holding the liquid. Further, the spacer 9 has a flat ring shape with a uniform wall thickness of 3.00±0.01 mm.

In this example, methyl methacrylate 100
Parts by weight, 1 part ethylene glycol dimethacrylate
0.2 ml of a polymer composition liquid consisting of 0.2 parts by weight of azobisisobutyronitrile was dropped onto the second molded part 6 of the female molded member 8, and the polymer composition liquid was added to the contact part 7 of the female molded member 8 with the spacer. A spacer 9 was placed, and the male molded member 4 was assembled along the main axis.

The mold thus prepared was placed in a thermostatic oven with hot air circulation and heated at 50°C for 12 hours and at 90°C for 6 hours. After heating, the mold was cooled to room temperature and then disassembled, and the molded contact lens was taken out.

There were no voids or voids on the surface or inside of the contact lens thus obtained, and no burrs were generated around the lens. The base curve of this contact lens is 8.00±0.02mm, the radius of curvature of the front curve is 8.47±0.02mm, and its size is
It was 8.5mm. Further, when the refractive power of the molded contact lens was measured using a lens meter, it was found to have a refractive power of -3.00±0.05 diopters, and the observed corona was also good.

Embodiment 2 FIG. 3 is a cutaway front view showing a second embodiment of the present invention. The male molded member 13 and the female molded member 17 are manufactured by machining stainless steel, and the spacer 18 is manufactured by injection molding low density polyethylene.

The first molded part 11 of this embodiment has a radius of curvature of 7.60±
First optical molding surface 10 made of a 0.005 mm concave spherical surface
The second molding part 15 has a cylindrical shape with an inner diameter of 8.8mm and a second optical molding surface 14 made of a convex spherical surface with a radius of curvature of 7.80±0.005mm. It has a liquid reservoir 15a for holding the polymer composition liquid. Further, the spacer 18 has a flat ring shape with a uniform wall thickness of 5.00±0.01 mm.

Polymerization composition liquid and tris-trimethylsiloxanylsilylpropyl methacrylate used in this example
40 parts by weight, 60 parts by weight of ethyl methacrylate, 2 parts by weight of triethylene glycol dimethacrylate,
Consists of a mixed solution of 0.5 parts by weight of azobisdimethylvaleronitrile.

The polymer composition solution was injected in the same manner as in Example 1, the mold was assembled, and the mixture was heated at 40℃ for 8 hours in a constant temperature bath for 60 minutes.
After polymerization was carried out by heating at -4 hours at 80°C and for 5 hours at 80°C, the mold was disassembled by cooling to room temperature and the molded contact lens was taken out.

The molded contact lens had no external defects such as sink marks or burrs, and had a base curve with a radius of curvature of 7.80±0.01 mm, a front curve with a radius of curvature of 7.60±0.01 mm, and a size of 8.8 mm. The refractive power of this lens was +2.00±0.05 diopters.

Embodiment 3 FIG. 4 is a cutaway front view showing a third embodiment of the present invention. The male molded member 22 and the female molded member 26 of this embodiment are made by injection molding polychlorotrifluoroethylene, and the spacer 27 is made by compression molding polyurethane rubber. In addition, 37 in the figure is the second optical surface, 3
8 is a second molding section.

The first molded portion 20 of the male molded member 22 has a radius of curvature.
It has a cylindrical shape with a diameter of 10.0 mm and has a first optical molding surface made of a convex spherical surface of 5.93±0.01 mm, and the second molding portion 24 of the female molding member 26 has a radius of curvature of 6.32±.
It has a cylindrical shape with an inner diameter of 10.0 mm and a second optical molding surface 23 consisting of a concave spherical surface of 0.01 mm.
4a. Also, the thickness of the spacer is 2.00±
It has a 0.01mm O-ring shape.

Example 1 was carried out using a polymer composition solution consisting of 88 parts by weight of 2-hydroxymethyl methacrylate, 10 parts by weight of methyl methacrylate, 1 part by weight of ethylene glycol dimethacrylate, 1.5 parts by weight of methacrylic acid, and 0.2 parts by weight of azobisisobutyronitrile. Inject in the same manner as above, assemble the mold, and heat in a constant temperature oven at 40°C for 10 hours, 60°C for 4 hours, and 80°C for 4 hours, then disassemble the mold and take out the molded contact lens. Ta.

The molded lens has no sink marks or burrs, a base curve with a radius of curvature of 5.93±0.02mm, and a radius of curvature of 6.32mm.
It had a front curve of ±0.02mm and a size of 10.0mm.

Next, the obtained dry lens was immersed in physiological saline and saturated and swelled to form a soft contact lens. This soft contact lens has a base curve radius of 8.0mm and a size of 13.5.±0.03mm.
It had a stable shape without deformation or turbidity. The refractive power of this lens was -3.00±0.08 diopters, and the water content was 40±0.3%.

Comparative Example 1 FIG. 5 is a cutaway front view showing a comparative example. The male molded member 30 and female molded member 33 of this comparative example were made of stainless steel, and no spacer was used. In addition, in the figure, 28 is a first optical surface, 29 is a first molded part, 31 is a second optical surface, 3
2 is a second molding section.

Put 0.2ml of the polymerization composition solution used in Example 2 into the mold.
After pouring and assembling the molds, heating was performed in a constant temperature bath in the same manner as in Example 1. When the mold was cooled to room temperature and then disassembled, and the molded contact lens was taken out, sink marks had occurred on the surface and periphery of the lens, and it could not be used as a contact lens.

Comparative Example 2 FIG. 6 is a cutaway front view showing another comparative example.
The male molding member 36 and the female molding member 39 are made of ethylene-vinyl acetate copolymer.
The first molded portion 35 of No. 6 has a first optical surface 34 around which a thin annular rim 40 is integrally attached. This thin rim 40 is provided to absorb the polymerization shrinkage by bending toward the center of the lens to reduce its height when the polymer composition exhibits volumetric shrinkage during polymerization. In addition, 37 in the figure is the second
The optical surface 38 is a second molded part.

The outer diameter of the male molded member 35 is 7.9 mm, and the radius of curvature is
It has a first optical surface 34 of 7.45±0.03 mm, an inner diameter of the female molded member 39 is 8.2 to 8.4 mm, and a second optical surface 34 has a diameter of 7.45±0.03 mm.
Optical surface 37 has a radius of curvature of 8.55±0.05 mm.

98 parts by weight of methyl methacrylate, 20 parts by weight of ethylene glycol dimethacrylate, 0.3 parts by weight of di-t-butylcyclohexyl peroxydicarbonate
Pour 0.3 ml of the polymer composition liquid consisting of parts by weight into the female molding member, combine the molds, and place in a constant temperature bath at 60℃.
After heating for 1.5 hours, cool and disassemble the mold.

The obtained contact lens has no sink marks or burrs, but the radius of curvature of its base curve is 7.47.
It was ±0.4mm, and good accuracy could not be obtained.
Further, the measurement results of the refractive power of this lens showed a significant variation of -7.50 to -8.50 diopters, which caused a practical problem.

Note that a digital contact gauge manufactured by NEIZ Corporation and a laser interferometer manufactured by Fuji Photo Equipment Co., Ltd. were used to measure the radius of curvature, and a projector manufactured by Nikon Corporation was used to measure the diameter. In addition, a stereomicroscope and an optical microscope were used to observe the appearance.

[Effects of the Invention] The contact lenses obtained according to the examples of the present invention do not have the problem of sink marks or the inability to obtain sufficient optical precision as seen in the comparative examples, and are free from the problems of molded contacts. There are no problems with burrs forming around the lens. That is, by using the contact lens mold according to the present invention, the following excellent effects can be obtained.

1. Contact lenses free of defects such as sink marks and burrs can be manufactured extremely easily without any machining.

2. The optical properties and physical properties of the molded lens are extremely stable and have excellent reproducibility.

3. Contact lenses with excellent optical precision can be manufactured with an extremely small number of steps and with good reproducibility.

4. It is possible to mold objects with extremely diverse designs such as base curves, front curves, bevels, flange curves, peripheral shapes, etc.

5 Since the molded member and spacer are independent,
Each material can be freely selected, and the range of materials that can be used is wide, and the optimal material can be selected depending on the type of polymerization composition liquid and the required precision.

6. Since the spacer does not come into contact with the polymerization composition liquid, the spacer material can be selected without considering problems such as dissolution or deterioration due to the polymerization composition liquid.

7. It can be used for both hard contact lenses and soft contact lenses, and is not limited by the mechanical processability of the contact lens material to be molded.

Such effects of the present invention are achieved by forming a fitting structure between the first molding member of the male molding member and the second molding part of the female molding member, thereby blocking the gap for contact lens molding from the outside. , the polymer composition solution does not come into contact with the air and excess polymer composition solution does not adhere to the surroundings of the lens, the spacer is made of a flexible material, and the volume shrinkage due to polymerization shrinkage is suppressed by reducing the thickness of the spacer. It can be absorbed by the proximity of the parts, and the molded parts themselves do not deform or shrink due to polymerization shrinkage, so important dimensions such as the radius of curvature and diameter of the contact lens to be molded do not change. This is achieved for the first time by the unique features of the mold according to the present invention.

[Brief explanation of the drawing]

FIG. 1 is a partially broken exploded perspective view showing a first embodiment according to the present invention, FIG. 2 is a longitudinal sectional front view of the first embodiment, and FIG. 3 is a longitudinal sectional front view showing a second embodiment according to the invention. FIG. 4 is a longitudinal sectional front view showing a third embodiment according to the present invention, and FIGS. 5 and 6 are longitudinal sectional front views showing a comparative example. 1, 10, 19...first optical surface, 5, 14, 2
3, 31, 37...second optical surface, 2, 11, 20
...First molded part, 6,15,24...Second molded part, 3,7,12,16,21,25...Contact part with spacer, 4,13,22...First molded member, 8, 17, 26... second molded member, 9, 1
8, 27...Spacer, 6a, 15a, 24a
...liquid reservoir, 10...circular rim.

Claims (1)

[Scope of Claims] 1. A contact lens mold characterized in that a male molding member and a female molding member are joined along the main axis via a spacer around the outer periphery of the molding portion of both molding members. 2. The male and female molding members have optical molding surfaces;
2. The contact lens mold according to claim 1, wherein the spacer has a ring shape having a common main axis with the molding member and is located at a position separated from the optical molding surface. 3. The contact lens mold according to claim 1, wherein the molding member is provided with a liquid reservoir. 4. The contact lens mold according to claim 3, wherein the liquid reservoir is provided in a slope shape around the insertion portion of the female molding member. 5. The contact according to claim 1, wherein the optical molding surface of the male molding member is substantially convex, and the optical molding surface of the female molding member is substantially concave. Lens mold. 6. The contact according to claim 1, wherein the optical molding surface of the male molding member is a substantially concave surface, and the optical molding surface of the female molding member is a substantially convex surface. Lens mold. 7. The contact lens mold according to claim 1, wherein the spacer component is made of a thermoplastic material or a rubber elastic body.