JPH03200210A - Production of contact lens - Google Patents

Abstract

PURPOSE:To obtain extremely high oxygen permeability without degrading optical characteristics and mechanical characteristics by subjecting a polymer or lens body to an etching then to a process for dissolving and removing fibrous materials having ferromagnetism after a polymn. process or working. CONSTITUTION:A magnetic field is impressed to a raw material monomer compsn. 5 contg. ferromagnetic fibers 4. The ferromagnetic fibers 4 are magnetized and a magnetic moment is generated in parallel with the fiber axes by impressing the magnetic field to the compsn. in such a manner, by which the magnetic moments are generated in parallel with the fiber axis and the fibers are so oriented as to parallel with the magnetic lines of force. The raw material monomer 5 is polymerized while this state is maintained. The high-polymer composite in which the ferromagnetic fibers 4 are substantially unidirectionally arrayed and exist at nearly uniform intervals is thereby obtd. The ferromagnetic fibers 4 are selectively dissolved and removed by utilizing the difference in the etching property between the ferromagnetic fibers 4 and the polymer. The many fine through-holes according to the diameter of the ferromagnetic fibers 4 are uniformly formed and the extremely high oxygen permeability is exhibited. The optical characteristics and mechanical characteristics of the blank material itself are maintained.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides a contact lens having extremely high oxygen permeability and having a large number of fine through-holes that do not impede the basic performance and function of a contact lens. This invention relates to a method for manufacturing lenses.

[Prior Art] Contact lenses are currently widely used as a means of vision correction, along with eyeglasses.

As is well known, contact lenses are used by directly contacting the cornea, so they have the optical properties such as refractive index and transparency, and mechanical properties such as strength, which are required as a means of vision correction.
In addition to improving physical and chemical stability, there is a need to improve the feeling of wearing and extend the time that can be worn continuously to reduce the hassle of putting on and taking off.

By the way, since the cornea, which is in direct contact with the contact lens, is an avascular tissue, the corneal tissue, especially the corneal epithelial tissue, takes in the oxygen necessary for metabolism from the atmosphere through tear fluid. Therefore, in order to improve the wearing comfort of contact lenses and extend the continuous wear time, it is necessary to ensure that a sufficient amount of oxygen is supplied to the corneal tissue even when wearing contact lenses. For this reason, attempts have been made to improve the oxygen permeability of contact lenses.

Methods to improve the oxygen permeability of contact lenses include using a substance with high oxygen permeability as a contact lens material, or using a highly water-absorbing polymer as a contact lens material, and increasing the water content of the material itself. For example, methods to improve oxygen permeability by increasing
There are two methods: improving the material of contact lenses, and increasing oxygen permeability by providing through holes in contact lenses. The latter method of providing through-holes in contact lenses can improve oxygen permeability regardless of the type of material, and oxygen or oxygen-containing tear fluid passes directly through the through-holes, so the former method is better. It has the advantage of superior oxygen permeability compared to other methods.

Methods for forming through-holes in such contact lenses include mechanical drilling using a drill or the like, drilling while melting a high molecular weight polymer using a laser, etc.; A method in which synthetic fibers are removed after polymerizing monomers in a container arranged in a contact lens shape (Japanese Patent Publication No. 54-19181)
No. 58-181436, Japanese Patent Application Laid-open No. 181436, 1983
-48022, etc.) are known.

[Problems to be Solved by the Invention] However, in the conventional machining and laser processing methods described above, the diameter of the through hole tends to increase, and furthermore, laser processing tends to cause optical damage due to carbonization of the polymer in the hole forming part. There was a problem in that the properties deteriorated significantly and it was difficult to obtain a practical contact lens.

Furthermore, among the above-mentioned conventional methods of providing through holes in contact lenses, Japanese Patent Laid-Open No. 56-161436 and Japanese Patent Laid-open No. 5
The method described in Japanese Patent Application No. 8-48022 is a method of removing synthetic fibers by swelling the polymer, so in many cases, the diameter of the through hole is reduced by the swelling of the polymer.
00μm or more, and the number is several to one.
Only about 0 pieces can be formed. For this reason, the effect of improving oxygen permeability is insufficient, and there has been a problem in that it is difficult to fully satisfy the current demands for improved wearing comfort and extended wearable time. Furthermore, by providing a through hole with a large diameter, the optical properties and mechanical properties of the contact lens obtained deteriorate, so there is a problem that it is difficult to obtain a practical contact lens.

In addition, the method for manufacturing contact lenses having through holes described in Japanese Patent Publication No. 54-19181 has a diameter of 3 to 40 μm.
In this method, through-holes are formed by dissolving and removing polyvinyl alcohol fibers of m. However, when trying to arrange a large number of such fine-diameter fibers in a resin raw material solution, the fibers naturally aggregate together and form so-called bundled fibers irregularly, which essentially results in large-diameter fibers. As a result, through-holes with large diameters are unavoidable. And it is known that it is very difficult to control and remove the presence of the above-mentioned focusing fibers, and therefore it is inevitable that there will be arbitrary through-holes whose diameter cannot be controlled, and the There was a problem in that the optical properties and mechanical properties were significantly deteriorated. Furthermore, since polyvinyl alcohol fibers have low heat resistance, they are susceptible to deformation, melting, etc. due to the heat during polymerization, and if the through holes are deformed or are significantly deformed, it becomes impossible to form the through holes themselves.

As described above, contact lenses with through-holes manufactured using conventional methods are not fully satisfactory in terms of improving oxygen permeability due to the diameter of the through-holes or the formation density of the through-holes. Since the optical properties and mechanical properties are deteriorated by providing such a material, it is extremely unsatisfactory in terms of practicality.

Therefore, an object of the present invention is to provide a method for manufacturing a contact lens having through-holes, which allows extremely high oxygen permeability to be obtained without deteriorating optical properties or mechanical properties.

[Means for Solving the Problems] That is, the method for manufacturing a contact lens having through-holes of the present invention involves applying a magnetic field to a raw monomer composition containing a ferromagnetic fibrous material to increase the ferromagnetism. a step of orienting the fibrous material in substantially one direction and polymerizing the raw material monomer composition while maintaining this state to obtain a polymer; After the polymerization step or the processing step, performing an etching treatment on the polymer or the lens body to dissolve and remove the ferromagnetic fibrous material. It is characterized by:

The raw monomer composition containing a ferromagnetic fibrous material used in the method for manufacturing a contact lens of the present invention has optical properties, mechanical properties and physical properties that can be used as a normal contact lens. - A fibrous substance having ferromagnetic properties (hereinafter referred to as ferromagnetic fiber) is mixed and dispersed in a raw material monomer that provides a chemically stable polymer.

The raw material monomer composition may contain a crosslinking agent, various additives, etc. as necessary.

Examples of the raw material monomer include (meth)acrylic acid and derivatives thereof. The derivatives of (meth)acrylic acid mentioned above include methyl (meth)acrylate, ethyl (
meth)acrylate, n-propyl(meth)acrylate, 1so-propyl(meth)acrylate, n-butyl(meth)acrylate, 1so-butyl(meth)acrylate, t-butyl(meth)acrylate, 2-ethylhexyl(meth)acrylate Acrylate, cyclohexyl (
Hydrocarbon (meth)acrylates such as meth)acrylate, n-octyl(meth)acrylate, benzyl(meth)acrylate; 2-trifluoro(meth)acrylate, trifluoroethyl(meth)acrylate, hexafluoro-1so-propyl(meth)acrylate; ) acrylate, tetrahydrononafluorohexyl (meth)acrylate, tetrahydrotridecafluorooctyl (meth)acrylate, tetrahydrohebutadecafluorodecyl (meth)acrylate, and other fluorine-containing (meth)acrylates; tris(trimethylsiloxy)silylpropyl ( meth)acrylate, tris(dimethylsiloxy)silylpropyl(
Silicon-containing (meth)acrylates such as meth)acrylate; 2-hydroxyethyl (meth)acrylate, 2
-Other (meth)acrylates such as hydroxypropyl (meth)acrylate, glyceryl mono(meth)acrylate and the like. Furthermore, (meth)acrylamide, N-methyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N.

Hydrophilic monomers such as N-diethyl (meth)acrylamide and N-vinylpyrrolidone can also be used. These monomers are used singly or as a mixture of two or more.

Examples of crosslinking agents that are usually added to the above-mentioned monomers in order to impart predetermined physical properties to contact lenses include (meth)acrylates having at least two double bonds in the molecule, such as allyl (meth)acrylates. ) acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate,
meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(
Examples include meth)acrylate.

Moreover, since the homopolymerization and copolymerization of the monomers described above are usually carried out in the presence of a radical polymerization initiator, the raw material monomer composition in the present invention also contains a radical polymerization initiator as necessary. Such radical polymerization initiators include:
There is no particular restriction as long as the initiator is used for vinyl polymerization, and examples thereof include azobisisobutyronitrile, azobisdimethylvaleronitrile, benzoyl peroxide, lauryl peroxide, and diisopropyl peroxycarbonate.

The ferromagnetic fibers mixed in such raw material monomers are a characteristic component of the present invention, forming fine through holes by etching treatment described below.

The material of the ferromagnetic fiber is not particularly limited as long as it exhibits a magnetization tendency to the extent that it can be substantially oriented in the negative direction in a magnetic field and can be dissolved and removed by etching. Such ferromagnetic fibers include iron,
Examples include metal fibers such as nickel and cobalt, alloy fibers containing these metals such as stainless steel, and composite fibers in which fibers made of non-ferromagnetic substances are coated with metals such as iron, nickel, and cobalt.

Further, the ferromagnetic fiber used in the present invention preferably has a diameter of less than 100 μm, more preferably 5 μm.
It is less than 0 μm. This is because the diameter of the ferromagnetic fiber directly affects the diameter of the through hole, and the diameter of the ferromagnetic fiber is 1
This is because if the diameter is 00 μm or more, the diameter of the resulting through-hole becomes too large, leading to deterioration of the optical and mechanical properties of the contact lens. Further, the length of the ferromagnetic fiber is not particularly limited as long as it can form a through hole with respect to the desired thickness of the contact lens.
If the length is too long, the fibers tend to get entangled with each other when dispersed in the raw material monomer composition (thus, in practical terms, the length of 1mm
It is preferable to set it to about 10 mm.

In the method for manufacturing a contact lens of the present invention, first, ferromagnetic fibers are blended into a liquid raw material monomer and thoroughly mixed to uniformly disperse the fibers.

Here, in the present invention, it is also possible to defibrate the ferromagnetic fibers by magnetic field orientation, which will be described later. It is preferable to form a uniformly dispersed state.

Note that defibration here means forming a state in which the respective fibers are separated from each other, and is a state in which there are no aggregated fibers in which a plurality of fibers are aggregated with each other. The defibration performed here can be performed using conventional methods such as stirring, shaking, and ultrasonic vibration. Defibrating the ferromagnetic fibers is important in forming independent through holes.

The amount of ferromagnetic fibers to be blended is determined by the number of through holes to be formed, and is not particularly limited as long as it can form a uniformly dispersed state with respect to the raw material monomer. However, practically, it is preferable that the volume ratio of the ferromagnetic fibers to the raw material monomers to be mixed is about 1% or less.

In the present invention, after the ferromagnetic fibers are uniformly dispersed in the raw material monomer, a magnetic field is applied thereto to substantially orient the ferromagnetic fibers in one direction.

The applied magnetic field is preferably one in which the lines of magnetic force are parallel and uniform, and its strength is sufficient as long as it can form a state in which the ferromagnetic fibers are substantially aligned in one direction. It is set appropriately depending on the magnetization tendency of the ferromagnetic fiber. In addition, the application of a magnetic field can be applied to, for example, glass, resin, etc.
This is carried out by placing a raw monomer composition in which ferromagnetic fibers are uniformly dispersed in a container made of a material that does not disturb the magnetic field, and placing it in a magnetic field in this state.

Further, either a permanent magnet or an electromagnet may be used to form the applied magnetic field. Only one magnet may be used, or two magnets may be used as a pair. For example 2
By using several magnets and arranging the north and south poles facing each other so that a predetermined gap is formed between them, a parallel and uniform magnetic field is created, which ensures the alignment of the ferromagnetic fibers. It is preferable for the purpose of understanding. Even if only one magnet is used, by using a yoke or the like, it is possible to form a state in which the north and south poles are substantially opposed to each other with a gap in between. Alternatively, magnetic field orientation can be achieved simply by placing a raw monomer composition in which ferromagnetic fibers are uniformly dispersed on the lines of magnetic force generated from a magnet. Furthermore, by providing minute irregularities on the surface of the magnet (magnetic pole in the case of an electromagnet), it is possible to selectively cause ferromagnetic fibers to exist in the convex portions, thereby improving the regularity of the arrangement of the through holes formed. It is effective in improving the

In the present invention, the raw material monomer composition is polymerized while maintaining the state in which the ferromagnetic fibers are substantially oriented in one direction in the raw material monomer composition, thereby forming a contact lens. A polymer composite material in which ferromagnetic fibers are substantially aligned in one direction is obtained.

As a method for polymerizing the raw material monomer, known polymerization methods such as thermal polymerization and photopolymerization are used, and are appropriately selected according to the raw material monomer.

Next, the ferromagnetic fibers are dissolved and removed by etching the polymer composite to form fine through holes. This etching treatment of the ferromagnetic fibers may be performed on the polymer composite itself, which is the material of the contact lens, or may be performed after the polymer composite has been previously processed into a lens shape.

For example, when etching is performed after processing into a lens shape, the lens is formed by cutting, cutting, polishing, etc. the polymer composite so that the ferromagnetic fibers reach from one surface of the lens to the other. Process it into a shape to obtain a lens body. Thereafter, this lens body is subjected to an etching process to dissolve and remove the ferromagnetic fibers, thereby producing a contact lens having the desired fine through-holes.

When processing into a lens shape after etching, the polymer composite is first etched to dissolve and remove the ferromagnetic fibers to form fine through holes. Next, the above polymer composite is cut, cut,
It is processed into a lens shape by polishing or the like, and a contact lens having the desired fine through-holes is produced.

The above etching treatment is performed using an etching solution that can selectively dissolve only the ferromagnetic fibers. That is, an etching solution that does not attack the polymer but can dissolve the ferromagnetic fibers is used, and the lens body is immersed in this etching solution.

The etching solution used in this case is not particularly limited as long as it satisfies the above conditions, but it is preferable to select the optimum one depending on the combination of the polymer and the ferromagnetic fiber.

Furthermore, since there is a very large difference in acid solubility between ferromagnetic fibers (metal fibers) and polymers, it is possible to selectively dissolve only the ferromagnetic fibers without substantially affecting the polymer. As the etching solution, acids such as hydrochloric acid, sulfuric acid, nitric acid, and hydrofluoric acid are preferably used because the etching solution can be removed.

Further, in order to perform the etching process smoothly and quickly, circulation of the etching solution, application of ultrasonic vibration, etc. are additionally preferably carried out. Furthermore, for the purpose of increasing the etching rate, it is also preferred to increase the temperature of the etching solution within a range that does not affect the polymer.

Note that the actual etching process is carried out by setting the process time in consideration of the type, concentration, temperature, and additional requirements of the etching solution.

In the contact lens obtained using the method for manufacturing a contact lens of the present invention, the diameter of the through hole is 100.
The through holes can be formed at a density of 10/am2 or more. in this way,
By having a large number of fine and uniform through-holes, the contact lens has extremely high oxygen permeability without deteriorating its optical properties or mechanical properties.

Here, when the diameter of the above-mentioned through-hole becomes large, such as exceeding 100 μm, the optical and mechanical properties of the contact lens deteriorate. The diameter of the through hole is more preferably 50 μm or less. Furthermore, if the density of through holes is as low as less than 10 holes/cm 2 , oxygen permeability cannot be sufficiently increased. In addition, if the formation density of through holes is too large,
Depending on the diameter of the through hole, the contact lens optical
In practice, it is recommended to use 10.
000 pieces/cm2 or less.

[Function] In the method for manufacturing a contact lens of the present invention, a magnetic field is first applied to the raw monomer composition containing ferromagnetic fibers. By applying a magnetic field in this way, the ferromagnetic fibers are magnetized, creating a magnetic moment parallel to the fiber axis,
The fiber axes are oriented parallel to the magnetic field lines. By applying a magnetic field in which the lines of magnetic force are parallel, the ferromagnetic fibers can be aligned substantially in one direction. Further, since the magnetized ferromagnetic fibers apparently have N poles and S poles at their respective ends, a repulsive force between the same poles occurs between the ferromagnetic fibers. As a result, the ferromagnetic fibers can be arranged in a defibrated state without agglomerating each other and at substantially equal intervals.

Furthermore, by polymerizing the raw material monomers while maintaining this state, a polymer composite in which the ferromagnetic fibers are substantially aligned in one direction and are present at approximately equal intervals can be obtained.

Then, by selectively dissolving and removing the ferromagnetic fibers by utilizing the difference in etching properties between the ferromagnetic fibers and the polymer, fine through holes corresponding to the diameters of the ferromagnetic fibers are uniformly and A large number of contact lenses are obtained. The contact lenses obtained in this way exhibit extremely high oxygen permeability due to the large number of through holes with small pore diameters and uniform pore diameters, and the optical and mechanical properties of the material itself are maintained, making it practical. It will be expensive.

〔Example] Examples of the present invention will be described below.

EXAMPLE As a ferromagnetic fiber, a stainless steel fiber (manufactured by Nippon Dansen ■) with a diameter of 8 μm cut into 3 mm pieces was prepared and mixed with an acrylic resin monomer (methyl methacrylate).

The mixing ratio was 450 stainless steel fibers to 2 g of monomer.

Next, 2 parts by weight of ethylene glycol dimethacrylate was mixed as a crosslinking agent into 98 parts by weight of the mixture of the monomer and stainless steel fibers, and azobisisobutyronitrile was further added as a polymerization catalyst to 98 parts by weight of the monomer. Te 0.1
Parts by weight were added and further mixed, and the mixture was placed in a glass cylindrical container with a diameter of 3 cm and sufficiently shaken to defibrate the fibers to obtain a raw monomer composition containing ferromagnetic fibers.

Next, the raw monomer composition containing the ferromagnetic fibers was placed in a glass cylindrical container, and a magnetic field was applied to orient the stainless steel fibers. As shown in Fig. 1, the magnetic field orientation of the stainless steel fibers is achieved by using an electromagnet 3 constructed by winding a coil 2 around the outer periphery of a magnetic core 1 (diameter 50 mm) made of iron, nickel, etc. A glass cylindrical container 6 containing a raw material monomer composition 5 containing fibers 4 is placed thereon, and the current flowing through the coil 2 is gradually increased to increase the magnetic field generated from the magnetic core 1. 4 was oriented perpendicularly to the upper surface of the magnetic core 1. Note that FIG. 1 shows a state in which the stainless steel fibers 4 are aligned substantially perpendicularly to the upper surface of the magnetic core 1.

While keeping the stainless steel fibers 4 aligned in one direction in this way, a band heater (not shown) placed around the glass cylindrical container 6 was used to heat the raw material monomer composition for 40 minutes in 15 hours. ℃ to 60℃, followed by 3
The raw material monomer is polymerized by raising the temperature to 120°C for an hour to obtain a polymer composite (contact lens material) mainly composed of polymethyl methacrylate in which stainless steel fibers 4 are arranged substantially in one direction. Ta.

Next, the obtained polymer composite is taken out from the container, and the polymer composite is cut, cut, polished, etc. so that the stainless fibers reach from one surface of the lens to the other surface, and a contact lens is formed. Processed into a shape with a center wall thickness of 0.15
A lens body of mm was obtained.

After this, the above lens body was washed with a 18% hydrochloric acid aqueous solution (solution temperature: 50%).
℃) for 1 hour to dissolve and remove the stainless steel fibers, thereby obtaining a contact lens having the desired fine through-holes.

When the contact lens thus obtained was observed, it was confirmed that the stainless steel fibers were completely dissolved and fine through holes were formed.

Further, the diameter of the through hole in the obtained contact lens was 8 μm. In addition, the formation density of the through holes is approximately 100
It was confirmed that the number of particles/ctn2 was formed at approximately equal intervals.

In addition, when evaluating the oxygen permeability of the contact lenses obtained in this way, for convenience of measuring the oxygen permeability coefficient,
A flat disc-shaped sample (thickness 0.15 mm) was prepared under the same conditions as the contact lens with minute through-holes described above, except that the shape was changed to a flat disc shape, and a gas permeability meter (Rika Seiki ■) was prepared.
When the oxygen permeability coefficient was measured using a gas permeability measuring device (K-315, manufactured by K.K., Ltd.), it was found to be 32,000 x 10" a
It was confirmed that it had an extremely high oxygen permeability of m3(STP)*cm/cm2*sec -cmHg.

Further, the visible light transmission spectra of the flat disk-shaped sample having the fine through-holes and a comparative sample of the same material and shape except for not having the through-holes were measured. As a result, visible range (400nm to 800nm)
The spectra of the two coincided with each other, and it was confirmed that the optical properties did not deteriorate due to the formation of the through holes, and that they had excellent optical properties.

Furthermore, when the tensile strength of the flat disk-shaped sample based on the above example and the comparative sample was measured, the comparative sample was 700 kg/c.
m2 of the sample according to the example was 680 kg/Cm2, and there was virtually no difference, confirming that the contact lens according to this example had excellent mechanical strength.

[Effects of the Invention] As explained above, according to the present invention, a contact lens having fine through holes can be easily manufactured.

In addition, the through-hole opening body has small and uniform pore diameters, and is formed in large numbers almost evenly, so it does not deteriorate the optical and mechanical properties of the contact lens material and has an extremely high oxygen content. It becomes possible to easily provide a highly practical contact lens that has transparency.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining a method for orienting ferromagnetic fibers in an embodiment of the contact lens manufacturing method of the present invention. 1...Magnetic core, 2...Coil, 3...
...Electromagnet, 4...Ferromagnetic fiber, 5...
...Raw material monomer composition.

Claims (1)

[Claims] (1) Applying a magnetic field to a raw material monomer composition containing a ferromagnetic fibrous material to substantially orient the ferromagnetic fibrous material in one direction, and while maintaining this state, The method includes a step of polymerizing a raw material monomer composition to obtain a polymer, and a step of processing the polymer obtained in the polymerization step into a lens shape to obtain a lens body, and after the polymerization step or processing step, A method for manufacturing a contact lens having through-holes, the method comprising performing an etching process on the polymer or the lens body and dissolving and removing the ferromagnetic fibrous substance.