JPH0627424A - Contact lens material and its production - Google Patents

Abstract

PURPOSE:To provide a contact lens excellent in dimensional stability and creep resistance. CONSTITUTION:This contact lens material is silicone resin obtd. by copolymerizing a silicon-contg. monomer with other copolymerizable monomer and not contg. >=3.5wt.% volatile component having <=700mol.wt. This silicone resin is irradiated with high energy radiation or immersed in a supercritical fluid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicone resin which provides a contact lens having excellent dimensional stability and creep resistance of the lens.

[0002]

2. Description of the Related Art Silicone resins obtained by copolymerizing a silicon-containing monomer with other copolymerizable monomers have hitherto attracted attention as contact lens materials because of their excellent oxygen permeability and have been variously developed. . For example, JP-B-52-33502, JP-B-58-4327, JP-B-62-8769, and JP-B-62-30.
613, JP-B-63-36646, JP-A-55-102613, JP-A-62-283313.
JP-A-60-165617, JP-A-61
There is a publication such as -87102. Further, as a method for improving the dimensional stability of a contact lens made of an oxygen permeable polymer using a siloxanyl-based monomer which is one of these silicon-based resins, a method of exposing to high-energy radiation is described in JP-B-62-62324. Has been done.

However, in this method, the main chain of the polymer is cleaved in parallel with the decrease of the residual monomer, and the residual monomer is hydrogenated by the hydrogen radicals generated at this time, so that a low-molecular weight siloxane compound is by-produced. Although the residual monomer is reduced, there are problems in dimensional stability of contact lenses and creep properties. When a contact lens made of a siloxanyl-based highly oxygen-permeable polymer material is worn for a long period of time, the radius of curvature of the lens is likely to be deformed along the radius of curvature of the cornea, and creep deformation is easily caused by the stress received during washing, Since the lens is soft, there is a defect that the lens is inverted and distortion is likely to occur.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a contact lens material having excellent dimensional stability and creep resistance of the lens.

[0005]

Means for Solving the Problems As a result of intensive studies by the present inventors, a silicon-based resin obtained by copolymerizing a silicon-containing monomer with another copolymerizable monomer, It has been found that an oxygen-permeable contact lens having excellent dimensional stability and creep resistance can be produced by using a contact lens material having a small content, and the present invention has been completed based on this finding.

That is, the present invention is as follows. 1. A contact lens material, which is a silicon-based resin and contains 3.5% by weight or less of a volatile component having a molecular weight of 700 or less. 2. In the method of manufacturing a contact lens material made of a silicone resin, a volatile component having a molecular weight of 700 or less is added to
A method for producing a contact lens material containing 3.5% by weight or less of the volatile component, which comprises irradiating the silicone resin or the contact lens material containing less than weight% with high energy radiation. 3. In the method for producing a contact lens material made of a silicone resin, the silicone resin containing a volatile component having a molecular weight of 700 or less or the contact lens material is dipped in a supercritical fluid to extract the volatile component. A method for producing a contact lens material containing 3.5% by weight or less of a volatile component having a molecular weight of 700 or less.

The silicone resin of the present invention is a resin obtained by copolymerizing a monomer containing a siloxanyl group or a monomer or macromer containing a polysiloxanyl chain with another monomer copolymerizable therewith,
Random copolymers, block copolymers, graft copolymers and the like are appropriately used depending on the monomer species used and the polymerization method. The swelling ratio when immersed in chloroform is 5
A cross-linked copolymer of not more than 00% is preferable because it has good dimensional stability.

The monomer containing a siloxanyl group, the monomer containing a polysiloxanyl chain, and the macromer used in the present invention include a siloxanyl group or an alkyl group in the polysiloxanyl chain, a hydrogen atom such as a phenyl group, a fluorine atom, a hydroxyl group, a carbonyl group. It may be substituted with a group such as tris (trimethylsiloxy) silylpropyl methacrylate, bis (trimethylsiloxy) methylsilylpropyl methacrylate, tris (trimethylsiloxy) silylethyl methacrylate, tris (trimethylsiloxy) silylbutyl methacrylate, tris. (Trimethylsiloxy) silylheptyl methacrylate, bis (trimethylsiloxy) silylpropyl methacrylate, 1,3-bis (3-methacryloxypropyl) -1,1 3,3-tetramethyl disiloxane, 1,3-bis (3-methacryloxypropyl) tetrakis (trimethylsiloxy) disiloxane, 1,5
Bis (3-methacryloxypropyl) -1,1,3
3,5,5-hexamethyltrisiloxane, 1,3-bis (2-methacryloxyethyl) -1,1,3,3-tetramethyldisiloxane, 1,7-bis (3-methacryloxypropyl)- 1,7-tetrakis (trimethylsiloxy) -3,5-tetramethyltetrasiloxane,
α, ω-bis (3-methacryloxypropyldimethylsiloxy) 3,3,3-trifluoropropylmethylpolysiloxane, α, ω-bis (3-methacryloxypropyl) tetrakis (trimethylsiloxy) silyl-3,
3,3-trifluoropropylmethylpolysiloxane,
α, ω-bis (2-methacryloxyethyldimethylsiloxy) 3,3,3-trifluoropropylmethylpolysiloxane, α, ω-bis (3-methacryloxypropyl) tetrakis (trimethylsiloxy) silyldimethylpolysiloxane, α , Ω-bis (3-methacryloxypropyl) dimethylpolysiloxane, α, ω-bis (2-
Methacryloxyethyl) dimethylpolysiloxane, α,
ω-bis (3-methacryloxy-2-hydroxypropyloxy-3-propyl) dimethylpolysiloxane and acrylates thereof can be used.

The other copolymerizable monomer in the present invention is the above-mentioned silicon-containing monomer or a monomer containing an active unsaturated group copolymerizable with a macromer,
Anything that can produce a transparent silicone resin,
Alkyl methacrylate, to improve mechanical strength
Alkyl acrylate, alkyl itaconate, alkyl crotonate, alkyl fumarate, and fluorine atom,
There is a hydroxyl group, the above unsaturated ester of an alkyl group substituted with a carbonyl group, etc., preferably methyl methacrylate, butyl methacrylate, butyl acrylate,
Trifluoroethyl methacrylate, trifluoroethyl acrylate, trifluoroitaconate, trifluoroethyl fumarate, hexafluoropropyl methacrylate and the like are used.

Further, in order to improve the water wettability of the lens, unsaturated carboxylic acids such as acrylic acid, methacrylic acid and itaconic acid, hydroxyethyl methacrylate, glyceryl methacrylate, diacetone acrylamide, N, N
-There are hydrophilic monomers such as dimethyl acrylamide, N-methyl acrylamide, N-vinyl pyrrolidone,
Acrylic acid, methacrylic acid, diacetone acrylamide, hydroxyethyl methacrylate, glyceryl methacrylate and N-vinylpyrrolidone are preferably used.

Further, in order to improve dimensional stability, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate. , Bisphenol-A-dimethacrylate, and acrylates thereof, vinyl methacrylate, allyl methacrylate, allyl acrylate, and other crosslinking monomers, and ethylene glycol dimethacrylate and tetraethylene glycol dimethacrylate are preferably used.

The method for producing the silicone resin of the present invention is not particularly limited. Generally, a radical initiator, a photosensitizer, etc. are mixed with a monomer mixture containing 5 to 98% by weight of a monomer containing silicon, It is produced by thermal polymerization in an air atmosphere or an atmosphere of an inert gas such as nitrogen gas, photopolymerization by irradiating with ultraviolet rays, or radiation polymerization by irradiating with high-energy radiation. Further, a resin made of a monomer that undergoes addition polymerization or polycondensation such as urethane reaction may be used.

The type and content of the silicon-containing monomer are appropriately selected depending on the target performance of the contact lens, particularly the oxygen permeability, but in order to increase the oxygen permeability, it is generally 25 to 80% by weight. Those are preferable. The polymerization conditions are appropriately determined depending on the shape, size, thickness, etc. of the resin. Further, a step of post-polymerizing at a high temperature of 90 ° C. or higher can be added for the purpose of further polymerizing the residual monomer after completion of the polymerization.

The volatile component in the present invention is an organic compound having a molecular weight of 700 or less, which usually has a boiling point of 200 ° C. or less at 2 mmHg when it is dissolved in a silicone resin. It is a general term for things that cannot be completely removed by normal operations such as vacuum drying. As the volatile component, a monomer used in the production of the resin, for example, a monomer having an active unsaturated group containing a siloxanyl group, an alkyl group, a fluoroalkyl group, a hydroxy group, a carbonyl group, etc., and hydrogenation of these monomers These include substances, by-products, and impurities contained in monomers.

Examples thereof include 1,3-bis (3-methacryloxypropyl) -1,1,3,3-tetra (trimethylsiloxy) disiloxane and 1,3-bis (3-methacryloxypropyl)-. Hydrogenated product of 1,1,3,3-tetramethyldisiloxane, 3-methacryloxypropyltris (trimethylsiloxy) silane, 3-methacryloxypropyltris (trimethylsiloxy) silane, 2-methacryloxyethyltris (trimethyl) Siloxy) silane, hexa (trimethylsiloxy) disilane, penta (trimethylsiloxy) methoxydisiloxane, tetra (trimethylsiloxy) silane, methyl methacrylate, ethyl methacrylate, butyl methacrylate, butyl acrylate, trifluoroethyl methacrylate, trifluor Ethyl acrylate, hexafluoroisopropyl methacrylate, hexafluoroisopropyl acrylate, methacrylic acid, hydroxyethyl methacrylate, glyceryl methacrylate, N- vinyl pyrrolidone, a diacetone acrylamide acid.

The silicone resin of the present invention has a molecular weight of 70.
It is necessary that the resin contains 0 or less volatile components in an amount of 3.5% by weight or less. Further, the appropriate level of the content is determined by the monomer composition of the silicone resin, the kind of the monomer, the molecular weight, the degree of crosslinking and the like. For example, in the case of a silicon-based resin having a high oxygen permeability having an oxygen permeability coefficient (DK) of 60 or more, that is, having a high content rate of a silicon-containing monomer, from the viewpoint of creep resistance and chemical resistance, 1.
It is preferably 5% by weight or less, and more preferably 1.5% by weight or less from the viewpoint of the restitution of the base curve. The smaller the content of these volatile components, the better the physical properties of the lens, which is preferable. However, if the treatment time is long, or if the content is extremely small, the mechanical strength is adversely affected, and particularly the impact strength is lowered. Usually, it is preferable that the content is 0.005% by weight or more. Further, among the volatile components, those having a molecular weight of less than 450 are preferably as small as possible because they have a strong plasticizing action on the resin, while components having a molecular weight of 450 or more have a function of imparting toughness to the resin. Therefore, it may be contained in a range not exceeding 3.5% by weight.

As a method of producing a contact lens material containing 3.5% by weight or less of a volatile component having a molecular weight of 700 or less and a silicone-based resin obtained by copolymerizing a silicon-containing monomer with another copolymerizable monomer, Any method can be used as long as it can reduce the volatile component having a molecular weight of 700 or less in the resin to 3.5% by weight or less, and is not particularly limited, but since contamination to the product is extremely small and safety can be secured, contact Lens preservative, surfactant aqueous solution that does not affect contact lenses, purified water or physiological saline, immersed at room temperature or higher, heat treated in an inert fluid such as silicone oil, and / or vacuum of 3 mmHg or less Preferred is a method of heat treatment below, a method of irradiating with high energy radiation, or a method of extracting with a supercritical fluid.

Irradiation with high-energy radiation is carried out by electron beam, γ
Line, x-ray, etc. under air atmosphere or under inert gas atmosphere such as nitrogen gas, argon gas, etc.
The extraction with supercritical fluid is carried out by irradiating the supercritical fluid at a dose of 10 minutes, and after introducing a fluid at a pressure and temperature above the critical point into the resin placed in a high-pressure container and immersing it for a certain period of time, the pressure and temperature are changed to normal pressure. After returning to normal temperature, the resin is taken out from the pressure vessel and the operation is performed.

The high energy radiation method has a molecular weight of 7
Used only for resin materials containing 5 or less, preferably 4 or less, by weight of volatile components of 00 or less.
When this volatile component is contained in an amount of 5% by weight or more, it is treated by heat treatment in an inert fluid such as silicon oil and / or heat treatment under a vacuum of 3 mmHg or less before irradiation with high energy radiation. It should be less than or equal to weight%. High energy radiation such as gamma ray and electron beam
A method of irradiating 100 kGy is used, and the irradiation amount is determined by the original residual amount of volatile components, the target residual amount value, the line intensity of high-energy radiation, etc., and generally 30 to 5
It is 0 kGy.

When high-energy radiation is applied, the volatile components are decomposed and removed, and at the same time, the silicon-based resin is decomposed to hydrogenate the residual monomer in the resin, resulting in non-polymerizable volatile components and low-molecular-weight silicon-based compounds. By-product. Since these by-products are low molecular weight compounds having a molecular weight of about 420 to 300, even if the amount is small, the creep resistance of the contact lens is significantly lowered. Further, since the main chain of the silicon-based resin is also broken, the structure of the silicon-based resin itself is changed, resulting in deterioration of physical properties such as creep resistance, reversion property and chemical resistance. For these reasons, conventionally, irradiation with high-energy radiation has not been able to sufficiently improve the effect of improving the silicone resin, which is a material for contact lenses.

However, when high-energy radiation is applied to a silicon-based resin containing 5% by weight or less of a volatile component having a molecular weight of 700 or less contained in the silicon-based resin before irradiation with high energy, the volatile component having a molecular weight of 700 or less is volatile. Thus, a silicon-based resin having a component content of 3.5% by weight or less can be obtained. In the supercritical fluid extraction method, the pressure is 75.3k.
g / cm ² or more, supercritical carbon dioxide fluid at a temperature of 31.1 ° C. or more, supercritical carbon dioxide fluid mixed with several% of water, or supercritical carbon dioxide fluid mixed with several% of ethanol, etc. It is possible to use a method in which the volatile component contained in the resin is extracted by immersing it in the resin. The treatment time is determined according to the residual amount of the original volatile component, the value of the target residual amount, the type of supercritical fluid and the conditions thereof, and when carbon dioxide is used, it is usually 110 kg / cm ^{2 to} 400 kg / c.
m ² , 32-90 ° C., 1-72 hours. The extraction method using a supercritical fluid of carbon dioxide is that carbon dioxide does not remain in the silicon-based resin, it is easy to process even if high-concentration volatile components remain, and there are no by-products and the product quality is high. It is preferable because it is high, the treatment is safe and simple, and only specific volatile components can be selectively extracted.

The contact lens manufactured from the contact lens material of the present invention has stable dimensional stability because the dimensional stability of the contact lens can be maintained within the range of ± 0.02 for a long time even if the lens has high power. Creep resistance is 0.20 or less even for low power lenses where the contact lens thickness is uniform throughout and shape rigidity is low, and the base curve is stable for a long time even if it is handled roughly when cleaning the lens. The feeling of wearing and the eyesight are improved. The restitution of the base curve is 50% or more, and even if a large deformation is applied to the lens during cleaning, the lens immediately returns to its original shape, so that the stability of the visual acuity when washed and worn is excellent. Further, since the chemical resistance is 0.06 or less, various eye drops can be used even when the lens is worn, so that the handling is simple and the durability of the lens is increased.

[0023]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. The characteristic evaluation in the examples was carried out by the following methods. 1. Content of Volatile Components Gas Chromatography [Shimadzu Corporation GC-
14A type detector FID]. The silicone resin is immersed in 10 times its weight of chloroform to completely elute the volatile components in the resin into chloroform,
Using a capillary column having an inner diameter of 2 μm and a length of 50 m supporting OV-1 (dimethyl silicon gum) as a liquid phase, the temperature was raised from 50 ° C. to 300 ° C. at 10 ° C./min, and 1,3-bis (3 -Methacryloxypropyl)-
Components having a retention time shorter than that of 1,1,3,3-tetra (trimethylsiloxy) disiloxane (molecular weight 682) were summed to obtain the amount of volatile components. The quantification was determined using a calibration curve prepared using 3-methacryloxypropyltris (trimethylsiloxy) silane [manufactured by Chisso Corporation] as a reference substance. 2. Dimensional stability of lens Base curve 7.70mm, power -3.00 and-
Keep the 9.00 lens in 37 ° C saline,
The lens was allowed to stand for 12 months, and the change in the base curve of the lens was measured with a contact gauge [CGX type manufactured by Knights Co., Ltd.]. 3. Creep resistance of lens A lens having a base curve of 7.70 mm, a power of −3.00, a center thickness of 0.14 mm, and a size of 8.8 mm is held in a saline solution at 24 ° C., and 1.2 g is radially applied to the lens. A load was applied and the sample was left standing for 7 days, and the change in the base curve (BC) of the lens was measured with a contact gauge.

Creep deformation amount = 7.70-B. C. Value 4. Returnability of base curve A lens with a base curve of 7.70 mm, power of −3.00, center thickness of 0.14 mm, and size of 8.8 mm is placed at 24 ° C.
1.2g in the radial direction of the lens
Then, the base curve of the lens after 7 days was measured with a contact gauge (measurement value A).
Then, after leaving the lens in physiological saline for 1 day at 24 ° C. without applying a load, the base curve was measured again (measurement value B) and evaluated by the following method.

Returnability = [(BA) / (7.70-
A)] × 100 5. Chemical resistance A base curve of 7.70 mm, power of −9.00, center thickness of 0.12 mm, and size of 8.8 mm was left standing in saline at 24 ° C. for 7 days, followed by 3 wt% sodium chondroitin sulfate. The amount of change in the base curve was measured by allowing it to stand in the chondron eye drop (manufactured by Kaken Yakuko Co., Ltd.) as a component for 3 days.

[0026]

Example 1 74 parts by weight of 3-methacryloxypropyltris (trimethylsiloxy) silane, 20 parts by weight of 2,2,2-trifluoroethyl methacrylate, 6 parts by weight of ethylene glycol dimethacrylate, and 0.1% of azobisisobutyronitrile. After mixing 27 parts by weight to form a uniform solution, the mixture was poured into a polypropylene test tube and stoppered.
After heating in a hot water bath at 5 ° C for 42 hours and then in a hot air oven at 50 ° C for 6 hours, the temperature is raised to 60 ° C for 1.5 hours, 70 ° C for 1.5 hours, and 90 ° C for 1 hour. Time, 1
Polymerization was carried out by heating at 00 ° C for 1 hour and 110 ° C for 1 hour.
Pull out the obtained rod-shaped silicone resin from the test tube 11
0.2m after heating in silicon oil at 0 ℃ for 2 hours
It was dried in a mHg vacuum dryer at 120 ° C. for 30 hours (the volatile component in this resin was 3.9 wt%). Then, after being processed into a button having a diameter of 12.7 mm and a thickness of 4.75 mm on a lathe, it was extracted with a supercritical carbon dioxide gas of 40 ° C. and 400 Kg / cm ² for 24 hours. The extraction button was annealed with warm water at 90 ° C. for 2 hours and then dried in a desiccator for 12 hours. The volatile component of the obtained resin is 0.2% by weight,
The Vickers hardness was 4.9 and the oxygen transmission coefficient was 74.2. The creep deformation of the lens made from this resin button is 0.01 mm, which is excellent in creep resistance, and the change in the base curve when immersed in physiological saline for 12 months is 0.01 mm, which is excellent in dimensional stability and chemical resistance. Sex is 0.01
mm, and the restitution property was 100%, indicating excellent lens performance.

[0027]

Example 2 A silicon resin button was manufactured in the same manner as in Example 1 except that supercritical carbon dioxide gas extraction was performed at 40 ° C. and 175 kg / cm ² . The volatile component of the obtained resin was 0.75% by weight. The creep deformation of the lens made from this resin button is 0.02m
m, dimensional stability 0.01 mm, chemical resistance 0.02 m
m, and the return property was 90%, which was excellent performance.

[0028]

Comparative Example 1 In Example 1, the volatile component in the resin that had been vacuum dried was 3.9% by weight, and the dimensional stability of the lens manufactured from this resin button was 0.03 mm, but the creep deformation was observed. The amount is 0.45 mm and the chemical resistance is 0.
The lens performance was inferior to the lens performance of 09 mm and the return property was 10%.

[0029]

[Example 3] In Example 1, a button was manufactured from the resin that had been vacuum dried, and was then irradiated with γ-rays at 40 kGy. The volatile component in the obtained button was 2.5% by weight. The creep deformation of the lens manufactured from this button was 0.12 mm, the dimensional stability was 0.02 mm, the chemical resistance was 0.06 mm, and the reversion property was 80%, showing excellent lens performance.

[0030]

[Comparative Example 2] In Example 1, the volatile component of the resin which had been polymerized in the hot air oven at 110 ° C was 5.2% by weight.
As a result of making a button from this resin and making a lens, the creep deformation amount becomes 0.5 mm or more and it becomes impossible to measure, and the dimensional stability becomes 0.10 mm for a lens with a power of -0.90 mm mm, chemical resistance, The returnability was also poor. (Lens by the method described in JP-A-58-194014)

[0031]

Example 4 34 parts by weight of 3-methacryloxypropyltris (trimethylsiloxy) silane, 40 parts by weight of 2,2,2-trifluoroethyl methacrylate, 20 parts by weight of methyl methacrylate, 6 parts by weight of methacrylic acid, tetraethylene glycol di 6 parts by weight of methacrylate and 0.15 parts by weight of azobisisobutyronitrile were mixed to form a uniform solution, which was then poured into a polypropylene test tube and capped, and then heated in a warm water tank at 50 ° C. for 16 hours. , Then 60
After heating to 90 ° C and heating for 32 hours and heating in a hot air oven at 90 ° C for 80 hours, take out the resin from the test tube 11
It was immersed in silicon oil heated to 0 ° C. and heated for 5 hours. The obtained rod-shaped silicon-based resin was put in a vacuum dryer, heated to 120 ° C. at 0.2 mmHg, and dried for 27 hours. The volatile component of the obtained silicone resin is 3.4% by weight.
Met. Next, a lens having a diameter of 12.7 mm and a thickness of 4.76 mm was processed into a button. The creep deformation amount was 0.09 mm, which was excellent in creep resistance, and the dimensional stability was 0.01 mm, which was excellent performance. The chemical resistance was 0.03 mm and the reversion property was 80%.

The reason why the present contact lens has excellent physical properties despite the fact that it contains 3.4% by weight of volatile components is that the content of the silicon-based monomer in the silicon-based resin is low and the rigidity of the resin is high. It is thought that this is due to the fact that

[0033]

Example 5 The lens manufactured in Example 4 was stored in physiological saline at 60 ° C. for 2 months. The volatile component in the lens measured by washing this lens with purified water and drying for 12 hours in a desiccator depressurized to 30 mmHg at room temperature was 2.4.
% By weight. The creep resistance of this saline solution treated lens is 0.06 mm, and the dimensional stability is 0.01 m.
m, chemical resistance was 0.01 mm, and reversion was 95%.

[0034]

EXAMPLE 6 34 parts by weight of 3-methacryloxypropyltris (trimethylsiloxy) silane, 60 parts by weight of 2,2,2-trifluoroethyl methacrylate, 6 parts by weight of ethylene glycol dimethacrylate, azobisisobutyronitrile. After mixing 15 parts by weight to form a uniform solution, the mixture was poured into a glass test tube and capped, and then heated in a hot water bath at 35 ° C. for 42 hours and then in a hot air oven at 50 ° C. for 6 hours. After that, the temperature was raised to 60 ° C. and the polymerization was carried out by heating for 1.5 hours, 70 ° C. for 1.5 hours, 90 ° C. for 1 hour, 100 ° C. for 1 hour, and 110 ° C. for 1 hour. The obtained rod-shaped silicone resin is taken out of the test tube and heated at 110 ° C.
It was immersed in the heated silicone oil and heated for 5 hours. After cooling, it was placed in a vacuum dryer and heated to 120 ° C. at 0.3 mmHg and dried for 27 hours. The volatile component of the obtained silicone resin was 2.2% by weight. Then, diameter 12.7
The button was processed into a button having a thickness of 4.76 mm, placed in a vacuum dryer, and dried at 80 ° C. for 24 hours at 3 mmHg. The volatile component in this button was 1.4%, and a lens was made from this button. The creep deformation amount was 0.05 mm, which was excellent in creep resistance, and the dimensional stability was 0.01 mm, which was excellent performance. The chemical resistance was 0.03 mm and the reversion property was 90%.

[0035]

The silicone resin of the present invention provides a contact lens which is excellent in dimensional stability, creep resistance, chemical resistance and restitution of the lens.

Claims (3)

[Claims] 1. A silicon-based resin having a molecular weight of 70.
A contact lens material containing 3.5% by weight or less of a volatile component of 0 or less. 2. A method for producing a contact lens material made of a silicone resin, which comprises irradiating high energy radiation to the silicone resin or contact lens material containing 5% by weight or less of a volatile component having a molecular weight of 700 or less. A method for producing a contact lens material containing the volatile component in an amount of 3.5% by weight or less. 3. A method for producing a contact lens material comprising a silicone resin, wherein the silicone resin or contact lens material containing a volatile component having a molecular weight of 700 or less is immersed in a supercritical fluid to form the volatile component. A method for producing a contact lens material containing 3.5% by weight or less of a volatile component having a molecular weight of 700 or less.