JPS6232770B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a rigid contact lens having a hydrophilic surface.

Contact lenses currently on the market are broadly classified into hard contact lenses made of poly(methyl methacrylate) or the like, and soft contact lenses made of poly(2-hydroxyethyl methacrylate) or silicone rubber.

Rigid contact lenses generally have the disadvantage of being inferior to soft contact lenses in that they are less comfortable when worn on the eye, but they do have superior optical properties (vision correction function, etc.), durability, and handling. The unique advantages of rigid contact lenses, such as their simplicity, cannot be ignored, and they are still widely used in the market.

In addition, in recent years, with the advent of hard contact lenses made of an oxygen-permeable material made by copolymerizing methyl methacrylate with methacrylate containing a silicone component, the usefulness of hard contact lenses has been reevaluated, and at present, the usefulness of hard contact lenses is being reevaluated. The current situation is that research is becoming more active.

However, the above-mentioned problem unique to hard contact lenses, such as poor wearing comfort, remains an important problem to be solved in this field.

It has been found that the above-mentioned problems with rigid contact lenses are largely due to the poor hydrophilicity of the lens surface rather than the hardness of the material. In other words, poly(methyl methacrylate) is originally a hydrophobic material, and oxygen permeable contact lens materials made by copolymerizing it with methacrylate containing a silicone component have even stronger hydrophobicity due to the presence of the silicone component. Express. In order to solve this problem, conventional measures have been taken such as (1) a method of copolymerizing by further adding a hydrophilic monomer or (2) a method of subjecting the lens surface to a low-temperature ashing treatment. However, method (1) causes a new drawback in that the material becomes flexible, which reduces the vision correction function that is an inherent advantage of rigid contact lenses, and method (2) reduces the hydrophilicity of the lens surface. It can be improved considerably, but
It is generally difficult to expect lasting effects.

The present inventors have developed a method for manufacturing hard contact lenses that overcomes the major drawback of hard contact lenses, which is the lack of hydrophilicity on the lens surface, without losing the inherent advantages of hard contact lenses. As a result of extensive research, we have discovered that (A) polymerizable monomers of ketalized sugar esters or ethers or ketalized sugar alcohol esters or ethers, and (B) polymerizable hard contact lens materials. A hard contact in which only the lens surface becomes effectively hydrophilic by molding the copolymer obtained by copolymerizing with a polymerizable monomer capable of forming a They discovered that it can be used as a lens and completed the present invention.

Sugar esters or ethers or sugar alcohol esters or ethers are hydrophilic compounds, but polymerizable monomers whose hydroxyl groups are ketalized and masked (hereinafter referred to as ketalized monomers) are polymerizable. It is a hydrophobic monomer similar to the monomers that can be formed into rigid contact lens materials.

Therefore, the copolymer obtained by copolymerizing the ketalized monomer with other monomers that can form hard contact lens materials (for example, methyl methacrylate) can be used practically as a material for hard contact lenses. It is something. A hard contact lens molded from such a copolymer exhibits a hydrophobic surface, but when this lens is subjected to acid treatment,
The ketalized sugar group or ketalized sugar alcohol group present on the lens surface is deketalized to introduce a hydroxyl group, and as a result, only the lens surface can be modified to have a hydrophilic surface texture. In other words, according to this deketalization reaction, the acid solution required for this reaction does not penetrate into the inside of the lens,
Only the lens surface can be effectively transformed into a hydrophilic property, and the essence of a hard contact lens can be maintained as it is.

Even in the case of conventional hard contact lenses, it is known that the surface properties of the lenses can be modified to some extent to be hydrophilic by treating them with strong acids such as hydrochloric acid or sulfuric acid; however, such surfaces are generally It has not been put into practical use because it has problems with stability and tends to have unevenness between hydrophilic and hydrophobic parts on the surface.

According to the present invention, it is possible to obtain a contact lens having a much better and more stable hydrophilic surface than the surface obtained by these conventional strong acid treatments.

Preferred examples of the ketalized monomer used in the present invention include 1.2:3.4-di-O-isopropylidene-6-O-methacryloyl-D-
Galactopyranoside (also known as 1,2:3,4-di-
O-isopropylidene-6-methacryloyl-D
-galactose), 1,2:5,6-di-O-isopropylidene-3-O-methacryloyl-D-
Glycofuranoside (also known as 1,2:5,6-di-O
-isopropylidene-3-O-methacryloyl-
D-glucose), 2,3-O-isopropylidene glycerol methacrylate, 2-methyl-2
-ethyl-4-methacryloxymethyl-1,3
-dioxolane, 2-methyl-2-isobutyl-
4-methacryloxy-1,3-dioxolane,
2-Methyl-2-phenyl-4-methacryloxymethyl-1,3-dioxolane, 2-methacryloxymethyl-spiro[4,5]-1,4-dioxadecane, 1,2:4,5-di-( Examples thereof include (O-isopropylidene) xylitol-3-methacrylate and allyl isopropylidene glycerol ether.

Preferred polymerizable monomers that can be polymerized to form a hard contact lens assembly include (1) methyl acrylate, ethyl acrylate,
Acrylic acid esters such as isobutyl acrylate, sec-butyl acrylate, tert-butyl methacrylate or cyclohexyl acrylate; (2) Methacrylic acid esters such as methyl acrylate, ethyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate or cyclohexyl methacrylate; (3) ) Pentamethyldisiloxanyl methyl methacrylate, heptamethyltrisiloxanyl ethyl acrylate, tris(trimethylsiloxy)
- Polysiloxanyl alkyl esters of acrylic acid or methacrylic acid such as γ-methacryloxypropylsilane, methyldi(trimethylsiloxy)silyl(propylglycerol) methacrylate (Japanese Patent Publication No. 52-33502, JP 54-118455) and JP-A-55-15110), (4) perfluoroalkyl methacrylates (see JP-A-51-46614), (5) propyl itaconate, isopropyl itaconate, butyl itaconate, hexyl itaconate,
Itaconate esters such as 2-ethylhexyl itaconate, heptyl itaconate or aryl itaconate or propyl crotonate, isopropyl crotonate, butyl crotonate, hexyl crotonate, 2-ethylhexyl crotonate, heptyl crotonate, aryl crotonate, etc. Examples include crotonic acid esters, (6) styryl compounds such as styrene, and allyl esters such as diallyl phthalate. Among these compounds, methyl methacrylate is particularly suitable as a raw material for hard contact lenses. Incidentally, many commercially available hard contact lenses use methyl methacrylate as the main component or one of the main components.

Further, by adding an appropriate auxiliary monomer component in addition to the above-mentioned polymerizable monomers, the physical properties and properties of the resulting contact lens can be improved. Such auxiliary components include (C) monomers added to stabilize the lens shape and improve solvent resistance, or (D) to impart appropriate flexibility to the lens and eliminate brittleness of the material. Examples include monomers added for specific purposes.

Examples of suitable monomers for use as the monomer (C) include crosslinking monomers such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and trimethylolpropane trimethacrylate. Furthermore, among the monomers mentioned in (6) above, divinylbenzene, allyl methacrylate, diallyl phthalate, etc. can also be used as crosslinking monomers.

Examples of suitable monomers for use as the monomer (D) include aliphatic carboxylic acid vinyl esters such as vinyl acetate and vinyl propionate.

Copolymerization and molding into contact lenses can be carried out using conventional polymerization techniques and molding techniques.

During copolymerization, the amount of ketalized monomer used is 100 parts (parts by weight, hereinafter the same) of the entire copolymerization reaction mixture.
The amount is preferably 5 to 40 parts. In other words, in general, as the mixing weight ratio of the ketalized monomer increases, the surface hydrophilicity of the resulting copolymer after acid treatment increases proportionally; When the amount of ketalized monomer increases, the surface hydrophilicity after acid treatment of the resulting copolymer becomes almost constant, and increasing the proportion of the ketalized monomer will only increase the brittleness of the resulting copolymer. Yes, the negative effects will be greater. Moreover, if the amount of the ketalized monomer used is less than 5 parts by weight, the desired effect will not be sufficiently expressed, which is not preferable.

When molding contact lenses, it is possible to carry out the copolymerization reaction in a mold corresponding to the shape of the contact lens and directly mold it into the shape of a contact lens, or to mold the polymerization mixture into a suitable mold or mold. It is also possible to polymerize the material in a container to form a block-, plate-, or round-bar-shaped material, which can then be formed into a contact lens of a desired shape by ordinary mechanical processing such as cutting and polishing.

The surface of the thus formed hard contact lens can be modified to be hydrophilic by subjecting it to a suitable acid treatment. Examples of acids effective for the acid treatment include hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, formic acid, and trifluoroacetic acid. If the concentration of acid used is high, there is a risk of deterioration of the material or cracks.
Conditions such as gradually increasing the concentration of the treatment solution are required. Appropriate acid concentration and immersion treatment time vary depending on the type of acid used and cannot be generalized, but for example, in the case of hydrochloric acid, it is necessary to
Approximately 20 minutes to 4 hours at a concentration of 50%; in the case of formic acid, approximately 10 minutes to 5 hours at a concentration of 20 to 40% at room temperature.
In the case of sulfuric acid, the treatment is preferably carried out at room temperature at a concentration of 10 to 50% for approximately 20 minutes to 4 hours. The development of hydrophilicity on the contact lens surface by this acid treatment is not strictly defined by standard treatment methods and standard treatment times, and can be carried out with good reproducibility within a certain tolerance range, so it is particularly suitable for industrial implementation. It's advantageous.

The hydrophilicity of the surface of the hard contact lens obtained by the method described above was evaluated as follows. That is, using a block-shaped sample with one smooth surface, fix the sample in distilled water so that the smooth surface becomes the bottom surface, and shoot bubbles with a volume of 2μ toward the bottom surface. It consists of measuring the contact angle (hereinafter referred to as θ) of the bubble with the bottom surface of the sample after a few seconds. θ can be measured indirectly from the image obtained by applying a parallel beam of light to a sample to which air bubbles are attached, which is further magnified by a lens and projected onto a screen. The smaller the value of θ, the better the hydrophilicity.

Next, the method of the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Methyl methacrylate (hereinafter referred to as MMA)
80 parts, 1.2:5.6-diisopropylidene-3
20 parts of -O-methacryloyl-α-D-glucol (hereinafter referred to as MDG), 0.2 parts of allyl methacrylate (hereinafter referred to as AMA), and azobisdimethylvaleronitrile (hereinafter referred to as ADMVN)
Mix 0.1 part thoroughly, add to the test tube, and incubate at 40℃ for 38 hours.
Heat polymerization was carried out sequentially under conditions of 16 hours at 50°C, 5 hours at 70°C, 5 hours at 80°C and 6 hours at 110°C to obtain a rod-shaped copolymer (ie, hard contact lens material). The copolymer was processed into a disk shape with one side polished flat and having a diameter of 10 mm and a thickness of 6 mm. When the θ of this disc-shaped sample was measured, it was 69.5°. Next, this sample was placed in an Erlenmeyer flask, a 50% aqueous hydrochloric acid solution was added thereto, and the mixture was stirred for 2 hours using a magnetic stirrer, and finally stirred for 30 minutes in a 0.024% aqueous sodium carbonate solution.

The thus obtained sample was washed with distilled water, further immersed in distilled water for 16 hours, and its θ was measured to be 28.7°, indicating that the hydrophilicity was significantly improved.

Example 2 Each component in the copolymerization was 50 parts of methyldi(trimethylsiloxy)silyl(propylglycerol) methacrylate, 36 parts of MMA, 10 parts of MDG, 4 parts of ethylene glycol dimethacrylate, and
An experiment was conducted in the same manner as in Example 1, except that 0.15 parts of ADMVN was used. The θ obtained from the sample before acid treatment was 69.2°, but the θ obtained after acid treatment was 33.6°, indicating that hydrophilicity could be greatly improved by acid treatment.

Example 3 Each component in the copolymerization was 90 parts of tert-butyl methacrylate, 10 parts of 2,3-isopropylidene glycerol methacrylate, 0.2 parts of AMA,
An experiment was conducted in the same manner as in Example 1, except that 0.15 parts of ADMVN was used. The θ obtained from the sample before acid treatment was 68.0°, but the θ obtained after acid treatment was 27.4°, indicating that hydrophilicity could be greatly improved by acid treatment.

Example 4 Each component in copolymerization was 80 parts of MMA, 20 parts of allyl isopropylidene glycerol ether,
An experiment was conducted in the same manner as in Example 1, except that 0.2 parts of AMA and 0.15 parts of ADMVN were used. The θ obtained from the sample before acid treatment was 46.7°, but the θ obtained after acid treatment was 32.6°, indicating that hydrophilicity could be improved by acid treatment.

The copolymers (hard contact lens materials) obtained in Examples 1 to 4 above were molded into the shape of a contact lens by ordinary mechanical processing, and the same acid treatment as in Examples 1 to 4 was performed. By applying this method, a hard contact lens with a hydrophilic surface could be obtained. When each of these contact lenses was actually worn on the eye, the lens surface was covered with tears, and the feeling of wearing was much better than that of conventional hard contact lenses.

Claims (1)

[Scope of Claims] 1 (A) a polymerizable monomer of a ketalized sugar ester or ether or a ketalized sugar alcohol ester or ether; and (B) polymerizable to form a rigid contact lens material. 1. A method for producing a hard contact lens having a hydrophilic surface, which comprises molding a copolymer obtained by copolymerizing a copolymer with a polymerizable monomer that can be used to form a contact lens, and then treating the copolymer with an acid.