JPS61223820A - Contact lens and its manufacture - Google Patents

Abstract

PURPOSE:To obtain lens equipped with an identifying mark which is a small signal but can be recognized clearly if the reflecting condition of rays is favorable, by installing the identifying mark to the surface of the contact lens in a projected form. CONSTITUTION:An identifying mark 2 is provided in the peripheral section of a lens 1. The reason why the mark is provided in the peripheral section is to avoid optical distortion to an eye when the lens is worn and the symbols are given in a convex condition. When the symbols are give in a convex condition. When the symbols are give in a convex condition, reflection of rays is changed largely and even small symbols can be discriminated easily. Moreover, it is necessary to install the symbols in a size of <=3mm<2>/ symbol and projected height of eta25mum, because feeling of physical disorder is given to eyes when the projected height of the convex symbol is too high.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to contact lenses with identification markings. More specifically, the present invention relates to a contact lens that has an identification mark that is small enough to cause no discomfort even when placed in the eye, but is clearly identified by the way light is reflected.

(Prior Art) Since soft contact lenses or hard contact lenses are small and are inserted into the eye, it has been difficult to imprint identification marks on them.

However, without identification marks, confusion may occur during manufacturing, inspection, and shipping at factories, as well as confusion among retailers and users.

Therefore, consideration has been given to adding identification marks to contact lenses.

For example, a method of dissolving a photosensitive resin by irradiating it with ultraviolet rays (Japanese Patent Publication No. 50-120642), a method of printing with photosensitive dye (Japanese Patent Application Publication No. 54-58508), and a method of engraving (Japanese Patent Publication No. 53-1988) -2692) etc. are known.

However, in all of these known examples, a concave mark recessed from the lens surface is provided.
The disadvantage is that it is difficult to distinguish when wet with water or tears. Furthermore, it was necessary to use resins such as photosensitive resins that were not necessarily necessary for lenses, which was difficult from a material standpoint.

[Problem that the invention seeks to solve]

In order to improve the above-mentioned drawbacks of the prior art, the present invention provides a technique for providing a protruding identification mark on the surface of a lens. In other words, the present invention provides a contact lens that has an identification mark that is small enough to cause no discomfort even when placed in the eye, but that is clearly identified by the way light is reflected.

[Means for solving problems]

In order to achieve the above object, the present invention consists of the following configuration.

[(1) A contact lens is characterized by having a convex identification symbol on its periphery, each symbol having a size of 3 mm2 or less, and the protrusion height of the symbol being 25 microns or less. contact lenses.

(2) In a method of manufacturing contact lenses by a static cast polymerization method using 6 molds and a concave mold, 1 symbol is placed on the periphery of the lens as a concave mold.
A method for manufacturing a contact lens, characterized by using a mold engraved with a symbol having a size of 25 microns or less and a protrusion height of 25 microns or less.'' The following will be described with reference to the drawings.

FIG. 1A shows a plan view of one embodiment of the contact lens of the present invention, and FIG. 1B shows a cross-sectional view of the same.

An identification symbol 2 is provided on the periphery of the lens 1. The reason why it is provided at the periphery is to prevent optical distortion from being caused to the eye when the lens is attached. The symbol is characterized by its convex shape. If the shape is convex, the reflection of light rays will be greatly different, making it easy to distinguish even small symbols.

Furthermore, each symbol must have a size of 3 mm2 or less, and the protrusion height of the symbol must be 25 microns or less. If one symbol is too large, it will distort the eye,
It is also because large symbols are unnecessary. If the height of the protrusion of the convex symbol is too high, it may give a sense of discomfort to the eyes, which is undesirable. The number of symbols does not matter as long as they are within the above range. Note that the symbol may be anything such as alphabets, kana, numbers, etc.

The contact lenses of the present invention include, for example, high water content soft contact lenses containing polyvinylpyrrolidone as a main component and low water content soft contact lenses containing polyhydroxyethyl methacrylate as a main component. Of course, hard contact lenses having polysiloxane bonds are also effective, and any other types of contact lenses, such as oxygen-permeable contact lenses having siloxane bonds and urethane bonds, do not matter. Among these, soft contact lenses are particularly effective for manufacturing process reasons.

Next, the method of the present invention will be explained.

In the method of the present invention, it is necessary to manufacture by static cast polymerization using six molds and a concave mold. This is because unlike the button method, cutting is not required, and it is possible to manufacture efficiently and to produce precise lenses.

Note that static cast polymerization refers to a method in which a polymerization solution is filled into six molds 11 and a concave mold 12 as shown in FIG. 2, and cast polymerization is performed in a stationary state.

The purpose of this is to insert a preferable symbol for the lens, each symbol having a size of 3 mm2 or less, in the area around the lens as a concave mold. 13 indicates such a marking.

The concave mold may be made of any material such as metal, plastic, or glass, but is preferably made of quartz glass, high-purity silica glass, or ceramics. This is because precise polymerization is possible and impurities are not eluted.

Further, the marking may be performed by any method such as cutting, but preferably, it is melted by laser beam irradiation treatment. This is because minute symbols can be inserted with high precision. The laser beam irradiation process uses, for example, a mask with symbols on a thin metal plate, and the laser beam is shot through the mask. The depth of the marking can be set by the intensity of the laser beam and the number of shots.

〔Example〕

Example 1 Convex mold with interference spherical surface (center radius of curvature R1 = 5.8
A soft contact lens was manufactured using a concave mold (center radius of curvature R2 = 5.8111111, inner diameter S = 10 mnr) having an interference spherical surface (with projections 5 on the periphery). The thickness T of the center of the space between the concave mold and the convex mold was 0.21 TllTl, and both of the concave and convex molds were manufactured from high purity silica glass "Pyrex" (trade name) by cutting and polishing. Then, the peripheral area of the mold is irradiated with a laser beam under heating, and the size of the symbol is approximately 0 on one side.
．． The protrusion height was 5 mm and the protrusion height was 5 microns.

The following polymerization stock solution was used.

2-Hydroxyethyl methacrylate (HEMA) 00
Cl Ethylene glycol dimethacrylate (EGDMA) 0.1 (] Azobisisobutyronitrile (AIBN>0.3 g) A stock solution was poured into a concave mold until it overflowed, and a convex mold was placed on it.

There were hardly any air bubbles.

The uneven mold assembly was held between clamps and heated in an air bath. Initially, it was tightened at 20 kgf and kept at 60°C for 0°5 hours, then increased to 80-f and kept at 100°C for 1°5 hours.

After cooling to room temperature, the clamp was removed. When the concave and concave molds were pulled apart, the lenses often adhered to the concave molds. The lens remaining in the mold often has a slight gap between it and the mold, so we were able to use a vacuum to suck it up. What could not be absorbed could be absorbed by pressing the mold with one's fingers to deform it. When the lens was boiled in water for 1 hour, it became a transparent hydrated soft contact lens.

The tensile strength of the non-hydrated lens removed from the mold is 5.
0 kgf/cJ or more, water content of water-containing lenses 37%, light transmittance of water-containing lenses (relative to thickness, same as below >90%,
The tensile strength of the water-containing lens was 8k11f/go. The identification symbols were clear and there was no confusion during factory inspections or at dealers.

Example 2 A convex-concave mold having a center radius of curvature Rt = 6.0 mm and a non-interference surface shaped like a rotating force object surface was made of quartz. It was manufactured from scratch using a polishing method. This concave mold was stamped in the same manner as used in Example 1. Then, a soft contact lens was manufactured in the same manner as in Example 1.

The stock solution used had the following composition.

N-vinylpyrrolidone (NVP> ・・・・・・・・・
・70C7 methyl methacrylate (MMA)・・・・−
----30Q Tetraethylene glycol dimethacrylate (TEGDMA>...0.05CI triallyl isocyanurate (TAIC)...0.1QAI8N
...Old...0.030 Fill the mold with the stock solution in the same way as in Example 1, and apply 10 to 10 with a force of 9f.
0℃, 0.5 hours! :30 to 9f, 120℃, 1
．． Polymerization was carried out for 5 hours, and the uneven mold was separated while still hot.

In many cases the lenses were strongly attached to the convex mold. When the surface of the convex mold was very clean, the adhesion was so strong that it could never be removed even after cooling. If the lens cannot be removed, just soak it in water for 3 hours and it will separate naturally during that time.

A transparent hydrous soft contact lens was obtained.

The tensile strength of the non-hydrated lens removed from the mold is 5.
The water content of the water-containing lens was 0 kvf/cJ, the water content of the water-containing lens was 68%, the light transmittance of the water-containing lens was 90% (95%, 10.1 mm), and the tensile strength of the water-containing lens was 12 and 9 f/al.

The identification mark on the obtained lens can be clearly seen with a magnifying glass.
Like Example 1, it was easy to handle.

When the obtained lens was subjected to a wearing test, it was possible to wear it continuously for two weeks in the case of lagophthalmia.

〔Effect of the invention〕

Since the present invention provides a protruding identification mark on the surface of the lens, the identification mark becomes clearer due to the degree of reflection of light rays. Furthermore, the symbol is small enough that it does not feel uncomfortable when placed inside the eye, making it easy to wear. In addition, the following effects are achieved.

■It becomes easier to distinguish between the left and right lenses worn by the wearer.

■It is easy to see the movement of the lens after wearing it through a slit lamp.

■There will be no confusion in the manufacturing process, making quality control easier.

■The engraved symbol remains permanently and has good durability.

[Brief explanation of drawings]

FIG. 1A shows a plan view of one embodiment of the contact lens of the present invention, and FIG. 1B shows a cross-sectional view of the same. FIG. 2 shows a preferred embodiment of the method of the invention. 1: Lens, 2: Identification symbol, 11: Convex mold, 12: Concave mold, 13: Engraving.

Claims (5)

[Claims] (1) A contact lens is characterized by having a convex identification symbol on its periphery, each symbol having a size of 3 mm^2 or less, and the protrusion height of the symbol being 25 microns or less. contact lenses. (2) The contact lens according to claim (1), wherein the contact lens is a soft contact lens. (3) In a method of manufacturing contact lenses by a static cast polymerization method using a convex mold and a concave mold, one symbol is 3 mm in the area corresponding to the periphery of the lens as a concave mold.
A method for manufacturing a contact lens characterized by using a mold engraved with a symbol having a size of ^2 or less and a protrusion height of 25 microns or less. (4) The method for manufacturing a contact lens according to claim (3), wherein the concave mold is made of quartz glass, high-purity silica glass, or ceramics. (5) The method for manufacturing a contact lens according to claim (3), wherein the marking is performed by melting or cutting by laser beam irradiation treatment.