CA1099663A - Process for producing hydrophilic silicone contact lenses - Google Patents
Process for producing hydrophilic silicone contact lensesInfo
- Publication number
- CA1099663A CA1099663A CA289,528A CA289528A CA1099663A CA 1099663 A CA1099663 A CA 1099663A CA 289528 A CA289528 A CA 289528A CA 1099663 A CA1099663 A CA 1099663A
- Authority
- CA
- Canada
- Prior art keywords
- lens
- gas plasma
- hydrophilic
- silicone
- monomer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Abstract
ABSTRACT OF THE DISCLOSURE
A hydrophilic silicone contact lens can be produced by pouring into a mold a silicone resin monomer, heating the monomer to effect polymerization, processing the resulting formed product into a lens, and then irradiating the surface of the lens with a low temperature gas plasma to impart hydrophilic pro-perty to the surface of the lens. Further, in order that the hydrophilic property can be maintained for a long period of time even if the lens is allowed to stand in the air, a hydrophilic resin film may be formed on the thus irradiated surface of the lens.
A hydrophilic silicone contact lens can be produced by pouring into a mold a silicone resin monomer, heating the monomer to effect polymerization, processing the resulting formed product into a lens, and then irradiating the surface of the lens with a low temperature gas plasma to impart hydrophilic pro-perty to the surface of the lens. Further, in order that the hydrophilic property can be maintained for a long period of time even if the lens is allowed to stand in the air, a hydrophilic resin film may be formed on the thus irradiated surface of the lens.
Description
16)99663 The present invention relates to a process for producing a contact lens of a hydrophobic silicone resin having a hydrophilic surface. More particularly, the invention per-tains to a process for producing a hydrophilic silicone contact lens which comprises the step of irradiating the surface of a silicone contact lens with a low temperature gas plasma, and a process for producing a silicone contact lens maintaining stabilized hydrophilic property for a long period of time which comprises the step of further forming a hydrophilic resin film on the thus gas plasma-treated surface of the lens.
Silicone resins have long been noted as materials for contact lenses since the resins have excellent flexibility, oxygen permeability, transparency, chemical stability and ther-mal stability. When a contact lens of a silicon resin is worn, however, the properties of the resin as a contact lens cannot be sufficiently displayed owing to the water-repellency of the resin. Therefore, silicone resins have heretofore not been generally accepted as a material for contact lenses.
The present inventors have now succeeded in the production of a very practical silicone contact lens, having improved wearability, by forming a contact lens from a silicone resin and then imparting hydrophilic property to the surface of the lens.
The contact lenses generally used at present in-clude hard contact lenses using polymethyl methacrylate as a base material and soft contact lenses using poly-2-hydroxyethyl methacrylate as a base material. The former have excellent ability to correct ametropia and are comparatively easy to handle.
Therefore, a major proportion of contact lenses are of this type.
The hard and hydrophobic lenses, however, have the defects of poor adaptability to the eyes and large foreign body sensation on wearing. On the other hand, the latter are contact lenses .
1~99663 of a flexible hydrophilic gel. Therefore, the latter have advantages in that they have excellent adaptability to ophthal-mic tissues and give small foreign body sensation on wearing.
~owever, the hydrogel contact lenses have the defects of poor dimensional stability, mechanical strength and ability to correct ametropia and they are difficult to handle, e.g., when sterili-zing the lens.
Both hard contact lenses and soft contact lenses used nowadays have the defect that they cannot be continuously worn for a long period of time. The chief reason therefor is considered to be the fact that the amount of oxygen supplied to the corneal tissues of the eye becomes insufficient owing to the wearing of contact lenses. Therefore, it is preferable that materials for contact lenses have sufficient oxygen permeability.
The present inventors considered that it was the ultimate object of contact lenses that the lenses could be con-tinuously worn for a long period of time. They also noted that silicone resins, as a base material for contact lenses, had enough oxygen permeability to supply an adequate amount of oxygen to corneal epithelium even when the eyes were shut. They con-sidered that almost ideal contact lenses would be produced if the silicon resins were more flexible and hydrophilic and had excellent adaptability to the eyes. As a result of extensive study, the present inventors have now found that contact lenses having a hydrophilic surface according to the present invention are novel contact lenses satisfying all the above-mentioned con-ditions.
There have been a few reports with regard to the production of contact lenses using a silicone resin, but the contact lenses have not yet been put to practical use since they are hydrophobic and thereby are poor in adaptability to the eyes and give large foreign body sensation on wearing.
Silicone resins have long been noted as materials for contact lenses since the resins have excellent flexibility, oxygen permeability, transparency, chemical stability and ther-mal stability. When a contact lens of a silicon resin is worn, however, the properties of the resin as a contact lens cannot be sufficiently displayed owing to the water-repellency of the resin. Therefore, silicone resins have heretofore not been generally accepted as a material for contact lenses.
The present inventors have now succeeded in the production of a very practical silicone contact lens, having improved wearability, by forming a contact lens from a silicone resin and then imparting hydrophilic property to the surface of the lens.
The contact lenses generally used at present in-clude hard contact lenses using polymethyl methacrylate as a base material and soft contact lenses using poly-2-hydroxyethyl methacrylate as a base material. The former have excellent ability to correct ametropia and are comparatively easy to handle.
Therefore, a major proportion of contact lenses are of this type.
The hard and hydrophobic lenses, however, have the defects of poor adaptability to the eyes and large foreign body sensation on wearing. On the other hand, the latter are contact lenses .
1~99663 of a flexible hydrophilic gel. Therefore, the latter have advantages in that they have excellent adaptability to ophthal-mic tissues and give small foreign body sensation on wearing.
~owever, the hydrogel contact lenses have the defects of poor dimensional stability, mechanical strength and ability to correct ametropia and they are difficult to handle, e.g., when sterili-zing the lens.
Both hard contact lenses and soft contact lenses used nowadays have the defect that they cannot be continuously worn for a long period of time. The chief reason therefor is considered to be the fact that the amount of oxygen supplied to the corneal tissues of the eye becomes insufficient owing to the wearing of contact lenses. Therefore, it is preferable that materials for contact lenses have sufficient oxygen permeability.
The present inventors considered that it was the ultimate object of contact lenses that the lenses could be con-tinuously worn for a long period of time. They also noted that silicone resins, as a base material for contact lenses, had enough oxygen permeability to supply an adequate amount of oxygen to corneal epithelium even when the eyes were shut. They con-sidered that almost ideal contact lenses would be produced if the silicon resins were more flexible and hydrophilic and had excellent adaptability to the eyes. As a result of extensive study, the present inventors have now found that contact lenses having a hydrophilic surface according to the present invention are novel contact lenses satisfying all the above-mentioned con-ditions.
There have been a few reports with regard to the production of contact lenses using a silicone resin, but the contact lenses have not yet been put to practical use since they are hydrophobic and thereby are poor in adaptability to the eyes and give large foreign body sensation on wearing.
- 2 -~99663 According to an embodiment of the present inven-tion, there is provided a process for producing a hydrophilic silicone contact lens which comprises the steps of:
(a) pouring into a mold a silicone resin monomer;
(b) heating the monomer to effect polymerization;
(c) processing the resulting formed product into a lens; and, (d) then irradiating the surface of the lens with a low temperature gas plasma to impart hydrophilic property to the surface of the lens.
Further, according to another embodiment of the present invention, there is provided a process for producing a hydrophilic silicone contact lens which comprlses the steps of:
(a) pouring into a mold a silicone resin monomer;
(b) heating the monomer to effect polymerization;
(c) processing the resulting formed product into a lens;
(d) irradiating the surface of the lens with a low temperature gas plasma to impart hydrophilic property to the 2Q surface of the lens; and, : (e) then forming a hydrophilic resin film on the thus irradiated surface of the lens.
In the present invention, a silicone resin monomer is first added with a catalyæt, mixed and then defoamed accor-ding to a usual method. The resultlng resin composition is poured into a clean metal, glass ox plastic mold and the resin composition is then heated to cure it. The thus obtained formed product is processed into a lens. However, the surface of the silicone resin lens is hydrophobic, poor in adaptability to the eyes, and large in foreign body sensation.
~(~99663 The thus formed hydrophobic silicone resin lens is t:reated with a low temperature gas plasma. As a result, hydrophilic property is imparted to the lens up to a depth of 30 m~ from the surface. As the gas, oxygen gas, nitrogen gas, ammonia gas, etc. may be used. In the case of an oxygen plasma, the density of carbonyl groups and hydroxyl groups on the surface of the silicone lens is increased. Also, in the case of an ammonia gas plasma, the formation of amino groups is possible. Even with a nitrogen plasma, hydrophilic property can be imparted to the surface of the silicone resin lens. In the irradiation treatment of the surface of the silicone resin lens with a low temperature gas plasma, a too high concentration of the plasma and a too long treatment time are undesirable since the reaction proceeds excessively in such cases. Conversely, a too low concentration and a too short treatment time cannot im-part hydrophilic property to the surface of the silicone lens.
Therefore, a controlled concentration of the plasma and a con-trolled treatment time must be selected in order to impart hydrophilic property to the surface of the silicone lens. In the present invention, as the plasma concentration it is suitable that the pressure of the gas flowing out of the gas cylinder is 0.1 - 0.5 kg/cm2, the pressure in the system is 1 - 5 mm~g and the high frequency output is 10 - 50 W and a suitable treatment time is 30 seconds - 5 minutes.
As the silicone resin used in the process of the present invention, conventional silicone resins such as ones of the following formulae, ' R
o - si - o L si or ~ R n 1(~9~663 _0~31_0~ olJsi C~I2 m wherein R is CH3, C2H5 or C6H5, M is 10-100 and n is 1,000-10,000, -~
may be used.
- Thus, hydrophilic property can be imparted to the surface of the low temperature gas plasma-treated silicone lens, and its wettability for water can be improved. In general, the degree of hydrophilic property is represented by the contact angle between a drop of water and a sample plane solid surface. The contact angle for hydrophobic silicone resins is 100 - 110, the contact angle for polymethyl methacrylate about 70 and the con-tact angle for hydrated poly-2-hydroxyethyl methacrylate about 40. The contact angle for the silicone lenses of the present invention is about 105 (hydrophobic) before irradiation treat-ment while the angle is 20 - 30 immediately after the irradia-tion treatment. Thus, the wettability of the surface of the silicone lens is remarkably improved. If the lens is allowed to stand and dry in the air after low temperature gas plasma treatment, the contact angle increases and the surface of the lens slowly turns hydrophobic. However, it has now been found that the hydrophilic property can be maintained as it is, if the lens is stored in water or in normal saline solution after the low temperature gas plasma treatment. It is seen from this fact that low temperature gas plasma-treated silicone contact lenses can be used in a hydrophilic state for a long period of time if the lenses are stored in water.
~J99663 The contact angle values for the low temperature gas plasma-treated silicone resins according to the present inve!ntion are shown in Table 1 in comparison with that for the untreated silicone resin and that for polymethyl methacrylate.
_ _ ~ . o o / ~ ., h ~ ~ ~ t~ L~ c~
S:~ ~ ~ ~ V
1- .
h * ~ o O O
~1 c~ ~s~ I l r~ ~ ~
*~ o o ._____ F::l +~ ~ ~ l ~ ~ ~ ~ U~
~ g~O I~ ~ ~ ,D~
. _ h ~ h S~ O O O O O
a) .,, +~ E~ Lr~ O O O O
~ ~ d ~~ ~ ~ ~ ~
E~ H ~
__ _ __ _ ~0 ~ cd ~ ~ h +~ a~ ~ ~D (~ N ~ ~ u) ~1 ~D h h O ~; Z h h P P ~ o : . _ h . ~ * ~ U~ ~ r I
. ~ h ~ ~1 h ~ *
P. ~> ~ :~ a~
El ~ ~ ~ h ~ ~
oo a) c~ oo _ . M c> ,1 ~ c~ ~1 ~ ~ ~ ~ ~ __ : - `7 -, 1~9~663 Only by the low temperature gas plasma irradia-tion treatment can the wettability of the surface of silicone contact lenses be sufficiently improved and their adaptability to the eyes be increased. Also, when the lenses are stored in water, the hydrophilic property of the lenses is maintained for a long period of time.
If the lenses are allowed to stand in the air, how-ever, their hydrophilic property is gradually lost as described above. In order that the lenses may maintain their hydrophilic property for a long period of time even if the lenses are allowed to stand in the air, a hydrophilic resin film is further formed on the low temperature gas plasma-treated surface of the silicone contact lenses according to the present invention.
As the hydrophilic monomer for forming said hydro-philic resin film, alkylene glycol monoesters of acrylic acid and methacrylic acid, acrylamide, methacrylamide and vinylpyrro-lidones are suitable. However, the hydrophilic monomers used in the process of the present invention are not limited to these compounds, other hydrophilic monomers can be used. Also, if necessary, a small amount of a hydrophilic crosslinking agent may be added.
There are two methods for forming a hydrophilic resin film on a lens. One is a method which comprises the step of graft-polymerizing a hydrophilic monomer onto the low tempe-rature gas plasma-treated silicone contact lens. In this case, the above-mentioned monomers may be used as a monomer and graft polymerization is carried out in water in the presence of a redox catalyst such as ceric ammonium nitrate or ammonium per-sulfate and sodium metabisulfit~ at room temperature. The surface of a silicone resin is activated by the plasma treat-ment and thereby a hydrophilic resin film can be easily formed - . , . -1~996~3 on the surface. Thus, the plasma-treated lens is placed in a solut:ion of 1 part by weight of a monomer in 100 parts by weight of water containing a catalyst. The reaction is effected by stirr:ing the mixture at room temperature for 1 to 2 hours.
The second method comprises the steps of subjecting a hydrophilic monomer to solution polymerization in a solvent, dipping the low temperature gas plasma-treated silicone contact lens in this solution, and then heating the lens removed from the solution in an electric oven to remove the solvent and simultane-ously complete the polymerization, thus a film being formed. Asthe solvent, any solvent which can dissolve the resulting pre-polymer or polymer uniformly may be used. For example, various alcohols, dimethylformamide, dioxane, benzene, toluene, etc. may be used. If surface precision is required, however, the evapo-ration speed must be carefully selected.
The thus treated silicone contact lens can main-tain its hydrophilic property for a long period of time even if it is allowed to stand in the air, in contrast with the silicone contact lens which has been subjected to only the low temperature gas plasma treatment.
The contact angle values of the silicone resin of the gas plasma-treated surface on which a hydrophilic resin film has been formed are shown in Table 2. When the hydrophilic resin film is formed, the contact angle immediately after the treat-ment is comparatively large but the subsequent change in contact angle is small.
.
.. .. . . . . .
.
1~9966a;
r I
h Q ~i A ~ _ ~1 10 _ , .
luss663 According to the present invention, silicone con-tact lenses which have excellent oxygen permeability, surface hydrophilic property, transparency and flexibility can be produced and the possibility of the continuous wearing of contact lenses for a long period of time has been increased. The conversion of the hydrophobic property o$ silicone resins into hydrophilic property according to the present invention is applicable to not only contact lenses produced therefrom but also to general sili-cone resins used widely in the medical field.
The following examples, in which all parts are ex-pressed by weight unless otherwise indicated, will serve to illustrate the practice of the invention in more detail.
~xample 1 To 10 parts of a silicone resin KE 106 LTV monomer was added 1 part of a RG catalyst (curing agent). The resulting resin composition was sufficiently stirred and vacuum-defoamed and then poured into a plastic-metal lens mold. The poured resin composition was heated in an electric oven at 65C for 4 hours.
The hardened resin composition which was formed into a lens was removed from the mold and heated at lOQC for 1 hour and then at 150C for 30 minutes to complete the polymerization. In the same manner, the above-mentioned resin composition was cast on a clean glass plate and heated to cure it. The thus obtained thin film was used as a sample for measuring the contact angle of the resin.
The silicone lens was then placed in a plasma tube which was maintained at a pressure of 2 mmHg by a vacuum pump while oxygen gas was passed through the tube. An oxygen plasma was generated at a high frequency output of 25 W and the lens was treated with the plasma for 1 minute.
The thus treated silicone contact lens was wetted thoroughly with water. Also, the contact angle of the similarl~
....
~0996~3 low temperature oxygen plasma-treated silicone thin film was about 20 immediately after the treatment. Thus, the hydrophilic property of the resin was remarkably improved as compared with the contact angle of 105 before the treatment. Even if the oxygen plasma-treated lens and thin film were stored in water, their hydrophilic property did not substanltially change.
Example 2 A silicone contact lens and a silicone thin film on a glass plate were produced in the same manner as in Example 1. The surface of the lens and the thin film were subjected to low temperature gas plasma irradiation treatment by using nitro-gen gas in place of oxygen gas. The contact angle of the thin film was about 20 and substantially no change in hydrophilic property was found when the lens or the thin film was stored in water.
Example 3 A silicone contact lens and a silicone thin film on a glass plate each having a hydrophilic surface were obtained in the same manner as in Example 1 except that oxygen gas was replaced by ammonia gas. The contact angle of the thin film was about 20 and storing of the lens or the thin film in water showed substantially no change in hydrophilic property.
Example 4 In a solution of 1 part of acrylamide in 100 parts of water were dipped the low temperature oxygen gas plasma-treated silicone contact lens and silicone thin film on a glass plate as obtained in Example 1. As a catalyst, 1 part of a 0.1 molar solution of ceric ammonium nitrate in lN-nitric acid was added thereto. The reaction was effected in a nitrogen stream at room temperature with stirring to graft-polymerize hydrophilic acryla-mide onto the surface of the lens or the thin film.
1~99663 This silicone contact lens maintained its hydro-philic property ~or a long period of time when stored in the air. The contact angle between a water drop and the thin film on a glass plate was 33 immediately after the formation of the thin film, 38 after one month and 40 after 3 months of storage in water.
Example 5 -~ In 100 parts of dimethylformamide were dissolved 10 parts of 2-hydroxyethyl methacrylate and 0.2 part of diisopropyl peroxydicarbonate. The resulting solution was reacted at 50C
for 1 hour with stirring to obtain a viscous prepolymer solution.
In the prepolymer solution were dipped the low temperature nitro-gen plasma-irradiated silicone contact lens and silicone thin film on a glass plate as obtained in Example 2. The dipped silicone contact lens and silicone thin film were then heated in an electric oven at 80C to remove the solvent and simultaneously complete the polymerization. Thus, a hydrophilic poly-2-hydro-xyethyl methacrylate film was formed on the surface of the lens and the thin film and a silicone contact lens and a silicone thin film on a glass plate each having durable hydrophilic pro-perty were obtained.
The contact angle between a water drop and the thin film was 46 immediately after the formation of the film, 49 after 1 month and 50 after 3 months of storage in water.
.
,
(a) pouring into a mold a silicone resin monomer;
(b) heating the monomer to effect polymerization;
(c) processing the resulting formed product into a lens; and, (d) then irradiating the surface of the lens with a low temperature gas plasma to impart hydrophilic property to the surface of the lens.
Further, according to another embodiment of the present invention, there is provided a process for producing a hydrophilic silicone contact lens which comprlses the steps of:
(a) pouring into a mold a silicone resin monomer;
(b) heating the monomer to effect polymerization;
(c) processing the resulting formed product into a lens;
(d) irradiating the surface of the lens with a low temperature gas plasma to impart hydrophilic property to the 2Q surface of the lens; and, : (e) then forming a hydrophilic resin film on the thus irradiated surface of the lens.
In the present invention, a silicone resin monomer is first added with a catalyæt, mixed and then defoamed accor-ding to a usual method. The resultlng resin composition is poured into a clean metal, glass ox plastic mold and the resin composition is then heated to cure it. The thus obtained formed product is processed into a lens. However, the surface of the silicone resin lens is hydrophobic, poor in adaptability to the eyes, and large in foreign body sensation.
~(~99663 The thus formed hydrophobic silicone resin lens is t:reated with a low temperature gas plasma. As a result, hydrophilic property is imparted to the lens up to a depth of 30 m~ from the surface. As the gas, oxygen gas, nitrogen gas, ammonia gas, etc. may be used. In the case of an oxygen plasma, the density of carbonyl groups and hydroxyl groups on the surface of the silicone lens is increased. Also, in the case of an ammonia gas plasma, the formation of amino groups is possible. Even with a nitrogen plasma, hydrophilic property can be imparted to the surface of the silicone resin lens. In the irradiation treatment of the surface of the silicone resin lens with a low temperature gas plasma, a too high concentration of the plasma and a too long treatment time are undesirable since the reaction proceeds excessively in such cases. Conversely, a too low concentration and a too short treatment time cannot im-part hydrophilic property to the surface of the silicone lens.
Therefore, a controlled concentration of the plasma and a con-trolled treatment time must be selected in order to impart hydrophilic property to the surface of the silicone lens. In the present invention, as the plasma concentration it is suitable that the pressure of the gas flowing out of the gas cylinder is 0.1 - 0.5 kg/cm2, the pressure in the system is 1 - 5 mm~g and the high frequency output is 10 - 50 W and a suitable treatment time is 30 seconds - 5 minutes.
As the silicone resin used in the process of the present invention, conventional silicone resins such as ones of the following formulae, ' R
o - si - o L si or ~ R n 1(~9~663 _0~31_0~ olJsi C~I2 m wherein R is CH3, C2H5 or C6H5, M is 10-100 and n is 1,000-10,000, -~
may be used.
- Thus, hydrophilic property can be imparted to the surface of the low temperature gas plasma-treated silicone lens, and its wettability for water can be improved. In general, the degree of hydrophilic property is represented by the contact angle between a drop of water and a sample plane solid surface. The contact angle for hydrophobic silicone resins is 100 - 110, the contact angle for polymethyl methacrylate about 70 and the con-tact angle for hydrated poly-2-hydroxyethyl methacrylate about 40. The contact angle for the silicone lenses of the present invention is about 105 (hydrophobic) before irradiation treat-ment while the angle is 20 - 30 immediately after the irradia-tion treatment. Thus, the wettability of the surface of the silicone lens is remarkably improved. If the lens is allowed to stand and dry in the air after low temperature gas plasma treatment, the contact angle increases and the surface of the lens slowly turns hydrophobic. However, it has now been found that the hydrophilic property can be maintained as it is, if the lens is stored in water or in normal saline solution after the low temperature gas plasma treatment. It is seen from this fact that low temperature gas plasma-treated silicone contact lenses can be used in a hydrophilic state for a long period of time if the lenses are stored in water.
~J99663 The contact angle values for the low temperature gas plasma-treated silicone resins according to the present inve!ntion are shown in Table 1 in comparison with that for the untreated silicone resin and that for polymethyl methacrylate.
_ _ ~ . o o / ~ ., h ~ ~ ~ t~ L~ c~
S:~ ~ ~ ~ V
1- .
h * ~ o O O
~1 c~ ~s~ I l r~ ~ ~
*~ o o ._____ F::l +~ ~ ~ l ~ ~ ~ ~ U~
~ g~O I~ ~ ~ ,D~
. _ h ~ h S~ O O O O O
a) .,, +~ E~ Lr~ O O O O
~ ~ d ~~ ~ ~ ~ ~
E~ H ~
__ _ __ _ ~0 ~ cd ~ ~ h +~ a~ ~ ~D (~ N ~ ~ u) ~1 ~D h h O ~; Z h h P P ~ o : . _ h . ~ * ~ U~ ~ r I
. ~ h ~ ~1 h ~ *
P. ~> ~ :~ a~
El ~ ~ ~ h ~ ~
oo a) c~ oo _ . M c> ,1 ~ c~ ~1 ~ ~ ~ ~ ~ __ : - `7 -, 1~9~663 Only by the low temperature gas plasma irradia-tion treatment can the wettability of the surface of silicone contact lenses be sufficiently improved and their adaptability to the eyes be increased. Also, when the lenses are stored in water, the hydrophilic property of the lenses is maintained for a long period of time.
If the lenses are allowed to stand in the air, how-ever, their hydrophilic property is gradually lost as described above. In order that the lenses may maintain their hydrophilic property for a long period of time even if the lenses are allowed to stand in the air, a hydrophilic resin film is further formed on the low temperature gas plasma-treated surface of the silicone contact lenses according to the present invention.
As the hydrophilic monomer for forming said hydro-philic resin film, alkylene glycol monoesters of acrylic acid and methacrylic acid, acrylamide, methacrylamide and vinylpyrro-lidones are suitable. However, the hydrophilic monomers used in the process of the present invention are not limited to these compounds, other hydrophilic monomers can be used. Also, if necessary, a small amount of a hydrophilic crosslinking agent may be added.
There are two methods for forming a hydrophilic resin film on a lens. One is a method which comprises the step of graft-polymerizing a hydrophilic monomer onto the low tempe-rature gas plasma-treated silicone contact lens. In this case, the above-mentioned monomers may be used as a monomer and graft polymerization is carried out in water in the presence of a redox catalyst such as ceric ammonium nitrate or ammonium per-sulfate and sodium metabisulfit~ at room temperature. The surface of a silicone resin is activated by the plasma treat-ment and thereby a hydrophilic resin film can be easily formed - . , . -1~996~3 on the surface. Thus, the plasma-treated lens is placed in a solut:ion of 1 part by weight of a monomer in 100 parts by weight of water containing a catalyst. The reaction is effected by stirr:ing the mixture at room temperature for 1 to 2 hours.
The second method comprises the steps of subjecting a hydrophilic monomer to solution polymerization in a solvent, dipping the low temperature gas plasma-treated silicone contact lens in this solution, and then heating the lens removed from the solution in an electric oven to remove the solvent and simultane-ously complete the polymerization, thus a film being formed. Asthe solvent, any solvent which can dissolve the resulting pre-polymer or polymer uniformly may be used. For example, various alcohols, dimethylformamide, dioxane, benzene, toluene, etc. may be used. If surface precision is required, however, the evapo-ration speed must be carefully selected.
The thus treated silicone contact lens can main-tain its hydrophilic property for a long period of time even if it is allowed to stand in the air, in contrast with the silicone contact lens which has been subjected to only the low temperature gas plasma treatment.
The contact angle values of the silicone resin of the gas plasma-treated surface on which a hydrophilic resin film has been formed are shown in Table 2. When the hydrophilic resin film is formed, the contact angle immediately after the treat-ment is comparatively large but the subsequent change in contact angle is small.
.
.. .. . . . . .
.
1~9966a;
r I
h Q ~i A ~ _ ~1 10 _ , .
luss663 According to the present invention, silicone con-tact lenses which have excellent oxygen permeability, surface hydrophilic property, transparency and flexibility can be produced and the possibility of the continuous wearing of contact lenses for a long period of time has been increased. The conversion of the hydrophobic property o$ silicone resins into hydrophilic property according to the present invention is applicable to not only contact lenses produced therefrom but also to general sili-cone resins used widely in the medical field.
The following examples, in which all parts are ex-pressed by weight unless otherwise indicated, will serve to illustrate the practice of the invention in more detail.
~xample 1 To 10 parts of a silicone resin KE 106 LTV monomer was added 1 part of a RG catalyst (curing agent). The resulting resin composition was sufficiently stirred and vacuum-defoamed and then poured into a plastic-metal lens mold. The poured resin composition was heated in an electric oven at 65C for 4 hours.
The hardened resin composition which was formed into a lens was removed from the mold and heated at lOQC for 1 hour and then at 150C for 30 minutes to complete the polymerization. In the same manner, the above-mentioned resin composition was cast on a clean glass plate and heated to cure it. The thus obtained thin film was used as a sample for measuring the contact angle of the resin.
The silicone lens was then placed in a plasma tube which was maintained at a pressure of 2 mmHg by a vacuum pump while oxygen gas was passed through the tube. An oxygen plasma was generated at a high frequency output of 25 W and the lens was treated with the plasma for 1 minute.
The thus treated silicone contact lens was wetted thoroughly with water. Also, the contact angle of the similarl~
....
~0996~3 low temperature oxygen plasma-treated silicone thin film was about 20 immediately after the treatment. Thus, the hydrophilic property of the resin was remarkably improved as compared with the contact angle of 105 before the treatment. Even if the oxygen plasma-treated lens and thin film were stored in water, their hydrophilic property did not substanltially change.
Example 2 A silicone contact lens and a silicone thin film on a glass plate were produced in the same manner as in Example 1. The surface of the lens and the thin film were subjected to low temperature gas plasma irradiation treatment by using nitro-gen gas in place of oxygen gas. The contact angle of the thin film was about 20 and substantially no change in hydrophilic property was found when the lens or the thin film was stored in water.
Example 3 A silicone contact lens and a silicone thin film on a glass plate each having a hydrophilic surface were obtained in the same manner as in Example 1 except that oxygen gas was replaced by ammonia gas. The contact angle of the thin film was about 20 and storing of the lens or the thin film in water showed substantially no change in hydrophilic property.
Example 4 In a solution of 1 part of acrylamide in 100 parts of water were dipped the low temperature oxygen gas plasma-treated silicone contact lens and silicone thin film on a glass plate as obtained in Example 1. As a catalyst, 1 part of a 0.1 molar solution of ceric ammonium nitrate in lN-nitric acid was added thereto. The reaction was effected in a nitrogen stream at room temperature with stirring to graft-polymerize hydrophilic acryla-mide onto the surface of the lens or the thin film.
1~99663 This silicone contact lens maintained its hydro-philic property ~or a long period of time when stored in the air. The contact angle between a water drop and the thin film on a glass plate was 33 immediately after the formation of the thin film, 38 after one month and 40 after 3 months of storage in water.
Example 5 -~ In 100 parts of dimethylformamide were dissolved 10 parts of 2-hydroxyethyl methacrylate and 0.2 part of diisopropyl peroxydicarbonate. The resulting solution was reacted at 50C
for 1 hour with stirring to obtain a viscous prepolymer solution.
In the prepolymer solution were dipped the low temperature nitro-gen plasma-irradiated silicone contact lens and silicone thin film on a glass plate as obtained in Example 2. The dipped silicone contact lens and silicone thin film were then heated in an electric oven at 80C to remove the solvent and simultaneously complete the polymerization. Thus, a hydrophilic poly-2-hydro-xyethyl methacrylate film was formed on the surface of the lens and the thin film and a silicone contact lens and a silicone thin film on a glass plate each having durable hydrophilic pro-perty were obtained.
The contact angle between a water drop and the thin film was 46 immediately after the formation of the film, 49 after 1 month and 50 after 3 months of storage in water.
.
,
Claims (9)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for producing a hydrophilic silicone con-tact lens which comprises the steps of:
(a) pouring into a mold a silicone resin monomer;
(b) heating the monomer to effect polymerization;
(c) processing the resulting formed product into a lens; and, (d) then irradiating the surface of the lens with a low temperature gas plasma to impart hydrophilic property to the surface of the lens.
(a) pouring into a mold a silicone resin monomer;
(b) heating the monomer to effect polymerization;
(c) processing the resulting formed product into a lens; and, (d) then irradiating the surface of the lens with a low temperature gas plasma to impart hydrophilic property to the surface of the lens.
2. A process according to claim 1, wherein said irra-diation is carried out with the gas flowing out of a gas cylinder at a pressure of 0.1 - 0.5 kg/cm2, a pressure in the system of 1 - 5 mmHg, a high frequency output of 10 - 50 W and a treating time of 30 seconds to 5 minutes.
3. A process according to claim 1, wherein said low temperature gas plasma is selected from the group consisting of oxygen gas plasma, nitrogen gas plasma and ammonia gas plasma.
4. A process for producing a hydrophilic silicone contact lens which comprises the steps of:
(a) pouring into a mold a silicone resin monomer;
(b) heating the monomer to effect polymerization;
(c) processing the resulting formed product into a lens;
(d) irradiating the surface of the lens with a low temperature gas plasma to impart hydrophilic property to the surface of the lens; and, (e) then forming a hydrophilic resin film on the thus irradiated surface of the lens.
(a) pouring into a mold a silicone resin monomer;
(b) heating the monomer to effect polymerization;
(c) processing the resulting formed product into a lens;
(d) irradiating the surface of the lens with a low temperature gas plasma to impart hydrophilic property to the surface of the lens; and, (e) then forming a hydrophilic resin film on the thus irradiated surface of the lens.
5. A process according to claim 4, wherein said irradiation is carried out with the gas flowing out of a gas cylinder at a pressure of 0.1 - 0.5 kg/cm2, a pressure in the system of 1 - 5 mmHg, a high frequency output of 10 - 50 W and a treating time of 30 seconds to 5 minutes.
6. A process according to claim 4, wherein said low temperature gas plasma is selected from the group consisting of oxygen gas plasma, nitrogen gas plasma and ammonia gas plasma.
7. A process according to claim 4, wherein at least one resin selected from the group consisting of resins of alky-lene glycol monoesters of acrylic acid and methacrylic acid, acrylamide, methacrylamide and vinylpyrrolidones is used to form said hydrophilic resin film.
8. A process according to claim 4, wherein a hydro-philic resin monomer is graft-polymerized onto the low tempera-ture gas plasma-treated silicone contact lens in water in the presence of a redox catalyst at room temperature to form said hydrophilic resin film on the thus irradiated surface of the lens.
9. A process according to claim 4, wherein a hydro-philic monomer is subjected to solution polymerization in a solvent, the low temperature gas plasma-treated silicone contact lens is dipped in this solution, and the lens is removed from the solution and heated in an electric oven to remove the sol-vent and simultaneously complete the polymerization, said hydro-philic resin film being formed on the irradiated surface of the lens.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA289,528A CA1099663A (en) | 1977-10-26 | 1977-10-26 | Process for producing hydrophilic silicone contact lenses |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA289,528A CA1099663A (en) | 1977-10-26 | 1977-10-26 | Process for producing hydrophilic silicone contact lenses |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1099663A true CA1099663A (en) | 1981-04-21 |
Family
ID=4109859
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA289,528A Expired CA1099663A (en) | 1977-10-26 | 1977-10-26 | Process for producing hydrophilic silicone contact lenses |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1099663A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5391589A (en) * | 1991-12-10 | 1995-02-21 | Seiko Epson Corporation | Contact lens and method of producing a contact lens |
-
1977
- 1977-10-26 CA CA289,528A patent/CA1099663A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5391589A (en) * | 1991-12-10 | 1995-02-21 | Seiko Epson Corporation | Contact lens and method of producing a contact lens |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US6689480B2 (en) | Surface-treated plastic article and method of surface treatment | |
| US3983083A (en) | Soft contact lenses and process for preparation thereof | |
| US4143017A (en) | Process of producing soft contact lenses | |
| US3619044A (en) | Rigid gas permeable contact lens with softer edge portion | |
| EP0605510B1 (en) | Surfactants used as contact lens processing aids | |
| JP3015103B2 (en) | Mold material for lens material containing silicone | |
| JP4267086B2 (en) | Process for the production of molded articles with wettable surfaces produced from latent hydrophilic monomers | |
| EP0785854B2 (en) | Method for treating plastic mold pieces | |
| JP2802287B2 (en) | Contact lens material and its manufacturing method | |
| US4169119A (en) | Method of molding an ocular membrane | |
| JPS61270723A (en) | Soft contact lens and manufacture thereof | |
| EP0295947B1 (en) | Gas permeable contact lens and method and materials for its manufacture | |
| HUT62711A (en) | Method for making soft spectacle lenses having high high oxygen permeability | |
| ATE85628T1 (en) | PROCESS FOR MANUFACTURE OF HYDROGEL MOLDINGS, INCLUDING CONTACT LENSES. | |
| DK147357B (en) | METHOD AND SUBSTANCE FORMING CONTACT LENSES | |
| IE873384L (en) | Contact lens fabricated from an oxirane containing¹hydrophobic polymer | |
| US4673539A (en) | Process for thermoformed articles | |
| JP2002113089A (en) | Polymer and lens for oculus using it | |
| US4921884A (en) | Hydroxy-substituted polymeric shaped hydrogel article | |
| US3816571A (en) | Fabrication of soft plastic lens | |
| CA1099663A (en) | Process for producing hydrophilic silicone contact lenses | |
| US4182723A (en) | Ocular membrane and method for preparation thereof | |
| FI70232C (en) | MJUKA KONTAKTLINSER OCH FOERFARANDE FOER DERAS FRAMSTAELLNING | |
| KR102006918B1 (en) | Method for manufacturing silicon-containing soft contact lens and Soft contact lens manufactured by the method and Composition for molding the soft contact lens | |
| US3813447A (en) | Hydrophilic synthetic high polymers for soft contact lenses and a process for manufacturing the same |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |