JPH0542984B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for manufacturing a soft ophthalmic lens, such as a contact lens, an intraocular lens, an artificial cornea, etc., which are prescribed in ophthalmology. More specifically, the present invention relates to a method for producing a soft ophthalmic lens that can be preferably applied to a soft contact lens that has excellent wearing comfort and oxygen permeability, and has suitable mechanical strength. [Prior Art] Among various materials that exist as ophthalmic lens materials, hydrous soft ophthalmic lens materials mainly made of poly-2-hydroxyethyl methacrylate or poly-N-vinylpyrrolidone absorb water and swell. It has been in the spotlight in recent years because it has the property of softening and is comfortable to wear, and it easily conforms to the cornea. However, when a material that softens with water is used, for example, as a soft contact lens, it has the following drawbacks. (b) Because it is water-containing, excreta from lachrymal fluid can easily accumulate inside the material, often causing serious damage to the eyes. (b) Bacteria and the like can easily breed on the lenses, and there is the hassle of having to be careful about how to use and store them, including periodic sterilization by boiling. In this field, in order to eliminate the disadvantages of soft contact lenses and not impair the feeling of wearing them, soft eye lens materials that are non-hydroscopic or only slightly water-containing are being used for soft contact lenses and other materials. However, these soft ophthalmic lens materials that do not contain water or exhibit only a slight water content must satisfy the following requirements. (b) It must have excellent oxygen permeability to ensure eye safety. (b) It must have a high degree of mechanical strength to prevent damage during use. (c) It has excellent moldability in order to be molded into the shape of an ophthalmic lens with high precision. In recent years, attempts have been made to apply materials that satisfy oxygen permeability to soft lenses in response to the above requirements, but materials with satisfactory mechanical strength and excellent moldability have yet to be found. Not yet. For example, the following four methods have been proposed as methods for manufacturing ophthalmic lenses such as contact lenses. (1) A method in which a monomer that provides a soft material is mixed with a monomer that will become a hard component, and then copolymerized. For example, n-butyl acrylate and n
- A method using a copolymer consisting of butyl methacrylate. (2) A method of adding reinforcement to soft materials. for example,
How to fill silicone with silica particles. (3) A method in which a polymer blend of different types of polymers is used as a final molded product. (4) A method using block-graft copolymers. If the method (1) above is adopted, it is possible to obtain a product with mechanical strength that is practically satisfactory, but on the other hand, oxygen permeability is reduced, so eye safety cannot be fully guaranteed. It has not been. In addition, when producing soft contact lenses using this method, since the material is soft at room temperature, the molding method is limited to molding, and therefore the molded product obtained may have unevenness, It is difficult or impossible to apply to products that require precision processing, such as contact lenses, because burrs occur frequently, volumetric shrinkage is large, and distortion is likely to occur. In method (2) above, inorganic fine particles such as carbon black and fibers exhibiting high elastic modulus such as glass fiber are used as reinforcing materials, but it is necessary to use materials with the desired mechanical strength. If a significant amount of reinforcing material is added to
Not only is it difficult to apply to contact lenses as transparency may be impaired;
If the reinforcing material is not properly dispersed, oxygen permeability may decrease. In addition, processing methods in this case generally involve mixing a reinforcing material with a linear or branched polymer that is the raw material for the soft material, and then injecting it into a mold, or dissolving the reinforcing material into a monomer that provides the soft material. Processing methods such as dispersing the monomer and injecting it into a mold and polymerizing the monomer are adopted, but no matter which method is used, unevenness and burrs are likely to occur as in (1) above, making it difficult to mold into contact lenses. This is not an appropriate processing method. The above method (3) is adopted as a method of mixing a linear or branched polymer that will be a hard component with a linear or branched polymer that provides a soft material with excellent oxygen permeability. However, different types of polymers generally have low compatibility with each other, tend to undergo large phase separation, and may become opaque, so not only can they not be applied to contact lenses, but the dispersion state of the soft and hard polymers may not be appropriate. Oxygen permeability may decrease. In addition, methods for molding contact lenses and the like include filling a polymer blend solution into a mold and then evaporating the solvent to mold it, or melting the polymer blend with heat, pouring it into a mold, cooling it, and molding it. However, it is difficult to apply to contact lenses because burrs and unevenness tend to occur. When the above method (4) is adopted, a block-graft copolymer containing one component each of a polymer that provides a soft material with good oxygen permeability and a polymer that provides high mechanical strength has a high oxygen permeability. Although it can be expected to develop high mechanical strength without impairing properties, it has the following problems. (b) Since the applicable polymerization methods are limited and the types of monomers are limited, it is technically difficult to create block or graft copolymers containing polymers that satisfy oxygen permeability and mechanical strength. Have difficulty. (b) Most of these copolymers are generally produced by solution polymerization or emulsion polymerization, which is not economical because reagent purification and solvents are expensive. (c) In many cases, it is difficult to obtain a transparent material. (d) As for the molding method, only the method using a polymer blend shown in (3) above can be applied, and unevenness and burrs may occur, making it difficult to apply to contact lenses. It is. In addition to the four methods mentioned above, various methods have been studied, such as methods using silicone rubber and methods using polyurethane. So far, no soft eye lens material has been produced that satisfies all of these requirements, such as having no burrs or unevenness. In particular, the method using silicone rubber had the problem that the lens surface was water-repellent, so it did not fit very well into the eye tissue. [Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned prior art, and can be precisely processed into the shape of an ophthalmic lens, and has increased mechanical strength without impairing oxygen permeability. The purpose of the present invention is to provide a method for manufacturing a soft ophthalmic lens. [Means for Solving the Problems] The present invention provides a flexible material obtained by polymerizing a monomer that provides a soft polymer containing (meth)acrylic acid ester as the main component, and a monomer that provides a hard polymer containing vinyl monomer as the main component. and a chain transfer agent, and polymerize the monomer that provides the hard polymer to obtain a polymer blend.The polymer blend is then machined into the shape of an ophthalmic lens, and then fixed from the polymer blend. The present invention relates to a method for manufacturing a soft ophthalmic lens, which includes removing uncured hard polymer. [Function] In the present invention, the hard polymer that is not immobilized on the soft material is removed from a molded product obtained by cutting a polymer blend consisting of a soft material and a hard polymer into a desired ophthalmic lens shape. By removing it, a highly precise soft contact lens with increased mechanical strength can be obtained without impairing oxygen permeability. Specifically, a polymer blend is obtained by impregnating a soft material with a monomer that provides a hard polymer containing a chain transfer agent, and then polymerizing the monomer that provides the hard polymer. The obtained polymer blend has excellent rigidity, so it can be subjected to mechanical processing such as cutting, and it is easy to process it into the desired ophthalmic lens shape. By immersing the soft material in water, the hard polymer that is not immobilized on the soft material is removed, and a water-free soft ophthalmic lens having the desired ophthalmic lens shape is obtained as a final product. In addition, in the present invention, when a polymer blend is obtained by polymerization, a part of the hard polymer can be immobilized in a soft material, and such a polymer blend can be used for ophthalmic use in the same manner as described above. When a lens is made, the polymer blend is a mixture of a soft material, some hard polymer immobilized in the soft material, and unimmobilized hard polymer. Removing the unimmobilized hard polymer from this polymer blend results in a polymer alloy in which the hard polymer is immobilized in a soft material, but surprisingly, the resulting ophthalmic lens is The mechanical strength is increased without any loss in transparency and without reducing the oxygen permeability of the soft material. [Example] The soft material made of a soft polymer used in the present invention has a crosslinked structure due to chemical bonds or ionic bonds, and these bonds are bonded to the solvent, monomers, or series of steps used in the present invention. Soft materials used here are those that do not disintegrate when subjected to mechanical processing such as cutting under normal environments and atmospheres in a state that is not swollen with water or other solvents. It is difficult or impossible to apply. For example, the glass transition temperature (hereinafter referred to as Tg) of a soft material is 40
If the temperature exceeds 40℃, especially 30℃, it will be stiff under normal environments and atmospheres without being swollen with water or other solvents, and machining such as cutting can be applied. The following are preferred in the present invention. Specific examples of monomers that provide the soft polymer include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-propyl (meth)acrylate, isobutyl acrylate,
n-butylene (meth)acrylate, 2-ethylhexyl acrylate, n-octyl (meth)acrylate, n-decyl methacrylate, n-dodecyl (meth)acrylate, n-tetradecyl (meth)acrylate, 2-ethoxyethyl acrylate, 3- ethoxypropyl acrylate,
Examples include (meth)acrylic acid esters such as 2-methoxyethyl acrylate and 3-methoxypropyl acrylate, but alkyl acrylates having 4 or more carbon atoms have good oxygen permeability and can be preferably used in the present invention. . These monomers may be used alone or in combination of two or more. The monomers that give these soft polymers include
Further, in order to increase oxygen permeability, other monomers may be added and copolymerized with the monomer providing the soft polymer. Examples of the other monomers include organosiloxysilylalkyl (meth)acrylates such as tris(trimethylsiloxy)silylpropyl(meth)acrylate, and fluoroalkyl(meth)acrylates such as trifluoroethyl(meth)acrylate and hexafluoroisopropyl(meth)acrylate. Examples include meth)acrylates. The other monomers are added in an amount of 0.1 to 100 parts by mole, particularly 10 to 50 parts by mole, per 100 parts by mole of the monomer that provides the soft material. Note that a crosslinking agent is added to the monomers that provide these soft polymers, or a mixture of these and other monomers, if necessary, to effect crosslinking. As the crosslinking agent, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol dimethacrylate,
1,4-butylene glycol dimethacrylate,
1,3-butylene glycol dimethacrylate,
Aryl diglycol carbonate, triaryl cyanurate, diaryl phthalate, N,
Examples include N'-methylenebisacrylamide, N,N'-methylenebismethacrylamide, and divinylbenzene. The crosslinking agent is usually a monomer that provides a flexible polymer or a mixture of these and other monomers.
0.1 to 10 mole parts per 100 mole parts, especially
It is used by adding 0.5 to 4 mole parts. In addition to the crosslinked soft material made of the monomers giving the soft polymer or these and other monomers prepared as described above, for example, a copolymer of n-butyl acrylate and 2-chloroethyl vinyl ether can be used with sulfur. It is possible to cross-link with , and such cross-linked materials can also be used in the present invention. A hard polymer is blended into the soft material prepared as described above. The hard polymer used in the present invention has a Tg of at least 60°C, preferably 90°C or higher, and has a Tg of at least 60°C, preferably 90°C or higher, and has a Tg that provides sufficient machinability to the polymer blend in a normal environment and atmosphere at room temperature. Polymers that provide hardness may be used. Specific examples of such hard polymers include polymethyl methacrylate, poly t-butyl methacrylate, polystyrene, poly t-butyl styrene, poly(meth)acrylonitrile, polymethacrylic acid, poly(meth)acrylamide, polyN-vinylpyrrolidone, and the like. Examples include vinyl polymers. These polymers may be used alone or in combination of two or more. Furthermore, among these hard polymers, vinyl polymers are preferably used in the present invention because radical or ionic polymerization methods can be used. These hard polymers have the role of facilitating cutting of soft materials, and at the same time immobilize some of the hard polymers in the soft materials, and then remove the hard polymers that have not been immobilized with solvent from the molded product of the polymer blend. By removing it, a polymer alloy mainly composed of soft material is formed, which has the role of increasing the mechanical strength required for ophthalmic lenses without impairing the oxygen permeability of the soft material. A polymer blend can be obtained by blending the soft material and the hard polymer, and the term polymer blend as used herein refers to a soft material, a part of the hard polymer immobilized in the soft material, and It is a mixture consisting of a hard polymer that is not immobilized in the soft material, and when the soft material and hard polymer are blended, the polymer blend has a hardness that can be cut at room temperature under a normal environment and atmosphere. It refers to a state in which a soft material and a hard polymer are mixed and dispersed. Therefore, it is not preferable that the soft material and the hard polymer are not completely compatible with each other because this will result in poor cutting. Additionally, the soft material and the immobilized hard polymer form a polymer alloy to the extent that the polymer alloy after removing the unimmobilized hard polymer can increase its mechanical strength without compromising oxygen permeability. It also needs to be distributed. The proportion of the soft material and the hard polymer in the polymer blend cannot be determined unconditionally because it varies depending on the hardness of the intended ophthalmic lens, but the proportion of the soft material in the polymer blend is 20 to 60% (by weight, The same applies hereinafter), and the hard polymer is preferably in the range of 80 to 40%. The polymer blend is obtained by impregnating a soft material with a monomer that provides a hard polymer and then polymerizing the monomer that provides the hard polymer. When preparing a polymer blend as described above, the soft material must be three-dimensionally insolubilized using a crosslinking agent or the like. Among the monomers that give a hard polymer, among those that have the ability to swell a soft material, a chain reaction occurs on the soft material under the polymerization conditions used in the present invention, and as a result, a part of the hard polymer is immobilized. A monomer that can be used can be selected. Monomers that provide such hard polymers include, for example, methyl methacrylate, t-butyl methacrylate, styrene, t-butyl styrene, (meth)acrylonitrile, methacrylic acid,
Vinyl monomers such as acrylamide and N-vinylpyrrolidone are used. Further, during the polymerization, an appropriate amount of solvents inert to the polymerization may be mixed in order to adjust the degree of swelling of the soft material. Such inert solvents include benzene, toluene, dimethyl sulfoxide, etc., and these inert solvents should be used in an amount not exceeding 30 parts by weight per 100 parts by weight of the monomer that provides the hard polymer. is preferred. Examples of methods for impregnating a soft material with a monomer that gives a hard polymer and then polymerizing the monomer include radical polymerization and ionic polymerization. Particularly when radical polymerization is applied, the polymerization reaction This is preferred because it is easy to carry out and control the chain transfer reaction. When applying the radical polymerization method, a radical polymerization initiator can be used, and such radical polymerization initiators include azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvalero), azo initiators such as nitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), organic peroxides such as benzoyl peroxide and di-t-butyl peroxide, potassium persulfate. , ammonium persulfate, etc., and the radical polymerization initiator is usually used in an amount of 0.01 to 0.5 mole part per 100 mole parts of the monomer that provides the hard polymer. The method of impregnating the soft material with a polymerization initiator together with a monomer that provides a hard polymer includes:
After the soft material reaches an equilibrium swelling state in a monomer that provides a hard polymer, a radical polymerization initiator is added to the monomer to start polymerization, or a radical polymerization initiator is mixed in the monomer in advance to create a soft polymer. Examples include a method in which the material is immersed to reach an equilibrium swelling state and then polymerization of the monomer is initiated. However, when using a soft material with a large volume, when the former method is adopted, polymerization starts before the radical polymerization initiator has sufficiently penetrated into the inside of the soft material. The latter method is used when using a soft material with a large volume as described above, as the polymer may not be polymerized, and as a result, there may be parts where the polymer is not blended, making cutting difficult. It is preferable to do so. Next, immobilization of a hard polymer into a soft material will be explained. Immobilization as used in the present invention refers to a state in which when a polymer blend consisting of a soft material and a hard polymer is immersed in a solvent, the hard polymer remains in the soft material without being eluted. The above-mentioned hard polymer can be immobilized by adjusting the polymerization initiator used during polymerization, polymerization temperature, polymerization time, etc., but especially by adjusting the amount of chain transfer agent added during polymerization. Therefore, the amount of hard polymer immobilized can be effectively adjusted freely. Examples of the chain transfer agent include mercaptans such as n-butylmercaptan, dodecylmercaptan, and thioglycolic acid, disulfides such as tetraalkylthiuram disulfide and xanthate disulfide, diazothioether,
Examples include 2-propanol, chloroform, bromoform, carbon tetrachloride, carbon tetrabromide, acetaldehyde, butyraldehyde, and among these compounds, sulfur-containing compounds with high chain transfer properties are particularly effective. The chain transfer agent is preferably used by being dissolved or emulsified and mixed with the monomer that provides the cured polymer. If the amount of chain transfer agent added is too small, most of the hard polymer will be immobilized in the soft material, and even if treated with a solvent, a large amount of the hard polymer will remain unremoved. The resulting product is no longer soft, but becomes hard or leathery with low shape stability, and if too much is used, the hard polymer will no longer be firmly fixed, making it impossible to reinforce the soft material. be. In the present invention, the amount of chain transfer agent added cannot be determined unconditionally because it varies depending on the type of soft material, the type of monomer providing the hard polymer, the amount of polymerization initiator added, etc.; 20g of methyl methacrylate was used as a monomer to provide a hard polymer, and a soft material (diameter: 13.5 mm, height 15 mm) was placed in the methyl methacrylate.
Poly n-butyl acrylate crosslinked as mm) was immersed to reach an equilibrium swelling state, then 0.16 mol% of azobisdimethylvaleronitrile was added to the methyl methacrylate as a polymerization initiator, and polymerization was carried out at 30°C. In this system, if the amount of dodecyl mercaptan added as a chain transfer agent is less than 0.010 mol% based on the methyl methacrylate, the amount of immobilized polymethyl methacrylate will be considerably large, and if the thickness of the molded product is made thin, Shape stability becomes poor. Also, the amount of dodecyl mercaptan added relative to the methyl methacrylate
If it is more than 0.2 mol%, there will be almost no amount of polymethyl methacrylate immobilized,
It becomes impossible to obtain a material with high mechanical strength. The polymer blend, in which a part of the hard polymer is fixed in the soft material as described above, is hard enough to be cut at room temperature in a normal environment and atmosphere, so it cannot be subjected to normal machining. It is easy to do. A molded product of a polymer blend contains a hard polymer in a soft material, and the soft material is cured in a swollen state, and will shrink when the hard polymer is removed, which will be detailed later. It is preferable to determine the shrinkage ratio of the molded product and cut the molded product into a desired size and shape according to the shrinkage ratio. Next, the cut molded article is immersed in a suitable solvent to remove the unfixed hard polymer contained in the soft material. The suitable solvent is one that has the ability to dissolve the unimmobilized hard polymer in the soft material and swell the soft material. Specific examples of such solvents include chloroform, methylene chloride, ethylene chloride, carbon tetrachloride, benzene,
Examples include toluene, xylene, tetrahydrofuran, dioxane, methyl ethyl ketone, ethyl acetate, methyl acetate, etc. In the present invention,
In addition to the solvents exemplified above, other solvents can also be used. Next, after sufficiently removing the unfixed hard polymer from the molded article, the molded article is dried to obtain an ophthalmic lens having a desired shape. In other words, the hard polymer that cannot be removed even if an attempt is made to remove it with a solvent or the like is reliably immobilized in the soft material. In addition, if the unimmobilized hard polymer is not sufficiently removed, the shape stability of the ophthalmic lens may become poor, and the eluate may harm the ocular tissue. It is necessary to sufficiently remove the hard polymer that is not present. The desirable amount of hard polymer immobilized in the soft material cannot be determined unconditionally depending on the type of soft material, the type of hard polymer, or the properties of the intended ophthalmic lens, but n-butyl acrylate is mainly used. In the case of a polymer alloy in which a hard polymer made of polymethyl methacrylate is immobilized in a soft material as a component, if the state of the polymer alloy is 100 mole parts in monomer units, the amount of immobilized polymethyl methacrylate is 5 in units
The amount of the chain transfer agent to be immobilized is desirably 50 parts by mole and can be controlled by appropriately selecting the amount of the chain transfer agent added. In this case, if the amount of immobilized polymethyl methacrylate is more than 50 mol parts, the material will be hard with poor shape stability, and if it is less than 5 mol parts, the soft material will not be reinforced. It will not result in a good polymer alloy. Thus, according to the method of the present invention, it is possible to obtain a soft ophthalmic lens in which a part of the hard polymer is fixed to a soft material, which also has very high mechanical strength without impairing oxygen permeability. It is. Next, the method for manufacturing a soft ophthalmic lens of the present invention will be explained based on Examples, but the present invention is not limited to these Examples. Examples 1 to 4 and Comparative Example 1 After degassing a mixture consisting of 98.9 mol parts of n-butyl acrylate, 1.1 mol parts of ethylene glycol dimethacrylate, and 0.03 mol parts of azobisdimethylvaleronitrile, a cylindrical glass with an inner diameter of 14.5 mm was prepared. Nitrogen gas was introduced into the glass container, and then a stopper was placed at the opening of the glass container, followed by heating at 30°C for 48 hours, 50°C for 5 hours, 80°C for 3 hours, and then 100°C. A soft material was obtained by heating and polymerizing for 2 hours. The obtained soft material was highly elastic and transparent at room temperature. Next, the obtained cylindrical soft material was cut into a length of 15 mm and placed in a cylindrical glass container with an inner diameter of approximately 22 mm into which a mixed solution of methyl methacrylate and dodecyl mercaptan prepared as shown in Table 1 was poured. After placing it in the solution and leaving it for 27 hours at 25°C to reach an equilibrium swelling state,
A predetermined amount of azobisdimethylvaleronitrile was injected into the solution, mixed, nitrogen gas was introduced into a glass container, and then polymerized at 30° C. for 3 days to obtain a polymer blend. The machinability of the resulting polymer blend was examined to see if it could be cut into a desired shape. Next, the molded polymer blend machined into a thin plate shape was placed in chloroform.
Soak for 24 hours to remove unimmobilized polymethyl methacrylate, which is a hard polymer component.
After drying, the physical properties of the resulting soft molded product were examined, including dimensional stability, transparency, oxygen permeability coefficient, punching load, elongation, and the amount of fixed hard polymer. (Dimensional stability) Shape of molded product of polymer blend (before removal of unimmobilized hard polymer component (polymethyl methacrylate)) and soft molded product after removal of unimmobilized hard polymer component When the shapes of both were similar, it was judged as "good", and when distortion was observed in the latter, it was judged as "poor". (Transparency) Visually inspected. (Oxygen permeability coefficient) Seikaken type film oxygen permeability meter (Rika Seiki Kogyo
Co., Ltd.) at 35°C. (Puncture load) Using an Instron-type compression tester, test the central part of a film-like soft molded product to 1/16 inch in diameter (approx.
A pressure needle of 1.59 mm) was applied, and the load at break (g) was measured at room temperature. (Elongation rate) Using an Instron-type compression testing machine, the length elongated until breakage was measured and calculated as a percentage (%). (Amount of immobilized hard polymer) The weight of the sample before immersion in the solvent (W ₁ ) and the weight after immersion in the solvent (W ₂ ) and those with a large amount of dodecyl mercaptan (i.e., there is almost no immobilization of polymethyl methacrylate) (considered to be)
Using _the sample obtained in Comparative Example ₁ as The amount was determined from the molar concentration (mol%) of the monomer unit. [Molar concentration of immobilized methyl methacrylate (mol%)] = (W ₂ /W ₁ −W ₂ ′/W ₁ ′)/[molecular weight of methyl methacrylate]/(W ₂ /W ₁ −W ₂ ′/ W ₁ ′) / [molecular weight of methyl methacrylate] + (W ₂ ′ / W ₁ ′) / [n-buty* * / molecular weight of acrylate] × 100

[Table] Based on the above results, the oxygen permeability coefficient and punch-through load were plotted against the amount of immobilized MMA, and the results are shown in Figures 1 and 2, respectively. From the above results, Examples 1 to 4 and Comparative Example 1
All of the obtained products have excellent oxygen permeability, but the material obtained in Comparative Example 1, in which polymethyl methacrylate is not immobilized, has low punching strength and is not suitable for practical use. Comparative Examples 2 to 6 In order to compare the present invention and the conventional copolymerization method, desired amounts of n-butyl acrylate monomer and methyl methacrylate monomer (second A cylindrical soft copolymer material was obtained under the same crosslinking agent ratio, initiator ratio, and polymerization conditions as in the previous soft material preparation, except for mixing (see the section on the amount of MMA in the copolymer in the table). The resulting cylindrical soft copolymer material has a length of 15 mm.
As shown in Table 2, the cut pieces were placed in a cylindrical glass container with an inner diameter of approximately 22 mm into which a mixed solution containing a large amount of dodecyl mercaptan was poured to prevent the methyl methacrylate and hard polymer from being immobilized too tightly. Polymer blends were produced in the same manner as in Examples 1 to 4, and the physical properties of the soft films after the hard polymer was removed were measured. The results are shown in Table 2.

[Table] Based on the above results, the oxygen permeability coefficient and punch-through load were plotted against the amount of immobilized MMA, and the results are shown in Figures 1 and 2, respectively. As can be seen from the results shown in FIGS. 1 and 2, if an attempt is made to increase the strength by simply increasing the amount of methyl methacrylate in the copolymer, the oxygen permeability coefficient decreases. [Effects of the Invention] According to the manufacturing method of the present invention, it is possible to form a soft ophthalmic lens with high precision, and by fixing a hard polymer inside a soft material made of a soft polymer, It is thought that a region (domain) of hard polymer is formed inside, and the hard polymer with the soft material as a sea forms an island-like polymer alloy. It is possible to obtain a material with improved mechanical strength without impairing the effects that cannot be obtained by copolymerization, that is, the inherent flexibility and oxygen permeability of a soft material. Furthermore, in the soft ophthalmic lens made of the polymer alloy obtained by the manufacturing method of the present invention,
Due to the finely divided dispersion of the hard polymer in the soft material, the content of immobilized hard polymer can be increased within an acceptable range without compromising the transparency, and the soft polymer (e.g. n
- There is no stickiness on the surface as seen in soft materials made only of (butyl acrylate). The soft ophthalmic lens obtained by the manufacturing method of the present invention is useful for ophthalmic lenses such as contact lenses, intraocular lenses, and artificial corneas, and is particularly suitable for use as it has good wearing comfort and oxygen permeability. Since it has a high mechanical strength, it has the advantage that it can be preferably applied to soft contact lenses.

[Brief explanation of the drawing]

Figure 1 is a graph showing the results of plotting the oxygen permeability coefficient against the amount of immobilized MMA of the soft molded products obtained in Examples and Comparative Examples. 2 is a graph showing the results of plotting the punching load against the amount of immobilized MMA of the soft molded product.

Claims (1)

[Claims] 1. A soft material obtained by polymerizing a monomer that provides a soft polymer containing (meth)acrylic acid ester as the main component, containing a monomer that provides a hard polymer containing vinyl monomer as the main component and a chain transfer agent. A polymer blend is obtained by impregnating the compounded liquid and polymerizing a monomer that provides the hard polymer, and then machining the polymer blend into the shape of an ophthalmic lens. A method for producing a soft ophthalmic lens, comprising removing a hard polymer. 2. The method for manufacturing a soft ophthalmic lens according to claim 1, wherein the soft material has a glass transition point of 40° C. or lower. 3. The method for producing a soft ophthalmic lens according to claim 1, wherein the hard polymer has a glass transition point of 60° C. or higher.