JPS641771B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a hydrous soft contact lens, and more specifically to a method for manufacturing a soft contact lens with a high water content. Water-containing soft contact lenses have been in demand in recent years because they fit the eye better and cause less foreign body sensation when worn compared to non-water-containing hard contact lenses such as methyl methacrylate (hereinafter referred to as MMA), silicone, and cellulose acetate butyrate. is increasing. These water-containing soft contact lenses have a water content of 35% and contain 2-hydroxyethyl methacrylate (hereinafter referred to as HEMA) as the main component.
There are many cases in which the water content can be increased, but various studies are currently being conducted in the direction of further increasing the water content. For example, a copolymer of N-vinylpyrrolidone (hereinafter referred to as NVP) and MMA, a copolymer of HEMA and NVP,
HEMA and methacrylic acid (hereinafter referred to as MAA)
copolymers with However, lenses with high water content obtained using these copolymers still have various problems, and at present no lens that fully satisfies the required performance has yet been developed. For example, materials containing NVP as a main component have the disadvantage that dirt easily adheres to them, and also have the problem that cutting and polishing, which has been widely used as a lens processing method, is not easy to apply. Also,
HEMA-NVP materials are mixed into HEMA
Due to the action of MAA and NVP, it has the disadvantage that the lens becomes yellow when repeated operations such as boiling sterilization are performed. In this regard, HEMA-MAA materials do not have problems in lens processing and do not have the disadvantage of being easily contaminated with dirt, but they require an extremely long time to obtain the desired high moisture content, are inefficient, and have a low swelling rate. There is a problem with hydration swelling in that there is a lot of variation, and this is a major obstacle when handling it as an actual product. In view of the above-mentioned current situation, the present inventors completed the present invention with the aim of developing a method for manufacturing soft contact lenses that has a high water content, is less dirty during use, and is easy to process lenses such as cutting and polishing during the manufacturing process. did. The present invention uses 90 to 99% by weight of hydroxyalkyl methacrylate or acrylate, and 1 to 10% of unsaturated carboxylic acid having one ethylenically unsaturated bond.
% by weight, 0.1 to 2 parts by weight of a crosslinking agent and 0.1 to 10 parts by weight of water are polymerized, formed into a lens shape, and then hydrated and swollen. . Hydroxyalkyl methacrylate or acrylate is the main component of the soft contact lens material according to the present invention. Representative among these are HEMA and hydroxypropyl methacrylate, with HEMA being the most representative.
These contents are determined by the balance of the contents of other components. The unsaturated carboxylic acid is a component for increasing the water content, has one ethylenically unsaturated bond in the molecule, and is copolymerizable with the main component. Methacrylic acid is typically mentioned, but acrylic acid, itaconic acid, and other unsaturated carboxylic acids can also be used. When these unsaturated carboxylic acids are less than 1% by weight, no significant effect is observed, and as the content increases, the water content of the soft contact lens product improves, but when it exceeds 10% by weight, the polymer becomes brittle. This causes problems in the durability of the lens. The crosslinking agent is added for the purpose of improving cutting abrasiveness, solvent resistance, and shape stability. As a crosslinking agent, polyfunctional monomers such as divinylbenzene, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, allyl methacrylate, and allyl acrylate are used. , diallyl succinate, divinyl succinate, trimethylolpropane trimethacrylate, diallyl phthalate, diethyl phthalate, and the like.
If the amount added is less than 0.1 parts by weight, no significant effect will be observed, and if it is added more than 10 parts by weight, the water content of the soft contact lens product will decrease, which is not preferable. A method of copolymerizing the above-mentioned hydroxyalkyl methacrylate or acrylate with an unsaturated carboxylic acid in the presence of a crosslinking agent is already known, but this conventional method requires an extremely long hydration time to obtain the desired moisture content. Even in that case, the moisture content is around 50% at most. The present inventors have discovered that by further adding water to the above monomer and polymerizing it, the hydration time can be shortened and the water content can also be increased to around 80%. In other words, by adding 0.1 to 10 parts by weight of water to 100 parts by weight of a mixture of HEMA and unsaturated carboxylic acid and polymerizing it, it is molded into a lens and swelled by hydration. In comparison, we were able to achieve an increase in moisture content of approximately 30% or more. In addition, the hydration swelling time, which would take about 5 days to reach equilibrium without adding water, could be shortened to less than 1 day. Although the effect of adding water has not been theoretically elucidated, the addition of water suppresses pseudo-crosslinking based on the carboxy groups of unsaturated carboxylic acids, which contributes to an increase in moisture content, leading to a dramatic increase in moisture content. It is also possible that he did. If the amount of water added is less than 0.1 parts by weight per 100 parts by weight of the mixture of HEMA and unsaturated carboxylic acid, no significant effect will be observed, and if it is more than 10 parts by weight, the polymer will become too soft and difficult to process into lenses. This is not preferable because the cutting abrasiveness becomes significantly worse. The method of the present invention will be explained in detail below in order of steps. After adding and mixing the required amount of water to each of the monomer components, the mixture is poured into a reaction vessel and heated for a certain period of time to carry out a polymerization reaction. Polymerization conditions vary depending on the monomers or composition used, but the polymerization may be carried out under usual conditions suitable for each. As the polymerization initiator, free radical polymerization initiators such as azobisisobutyronitrile, azobisisovaleronitrile, benzoyl peroxide, lauroyl peroxide, and cumene hydroperoxide are usually used. The polymer is formed into a rod shape, a plate shape, etc. depending on the shape of the reaction vessel, and these polymers are formed into a contact lens shape by cutting or polishing. At this stage, the polymer is relatively hard and can be easily cut and polished. The lens-shaped polymer thus obtained is subjected to a hydration swelling treatment to form a high water content soft contact lens for use. The hydration swelling treatment is carried out by immersing the above polymer in an aqueous solution containing alkali metal ions or alkaline earth metal ions. Usually, it is heated and left for several hours. Due to this hydration and swelling treatment, the
It is possible to produce soft contact lenses with a high water content of 80% to 80%. According to the method of the present invention, since NVP is not used as the main component of the material, dirt is less likely to adhere during use, and since it is relatively hard before hydration and swelling treatment, cutting and polishing are easy. Yes, it can significantly shorten the hydration swelling time, and
Since it is a soft contact lens with a high water content of 80%, it has the advantage of being easy to wear and having good oxygen permeability. In addition, by adding water and performing polymerization, the phenomenon of clouding of the polymer due to heterogeneous polymerization,
Since the so-called tyoke phenomenon can be prevented, a wide range of polymerization conditions can be selected, and restrictions on polymerization conditions can be eliminated. In the method of the present invention, a milky white phenomenon may occur after the hydration swelling treatment, and this phenomenon is more likely to occur especially as the water content increases. Although this opalescent phenomenon does not impair the transparency of the lens, it is not desirable in terms of optical properties as a contact lens. This phenomenon can be solved by the method described below. The improved method of the present invention comprises 80 to 98% by weight of hydroxyalkyl methacrylate or acrylate;
For 100 parts by weight of a mixture consisting of 1 to 10% by weight of an unsaturated carboxylic acid having one ethylenically unsaturated bond and 1 to 10% by weight of a monomer having a six-membered carbon ring that can be copolymerized with these, crosslinking The method is characterized in that a mixture containing 0.1 to 2 parts by weight of the agent and 0.1 to 10 parts by weight of water is polymerized. The details regarding the composition and the method for molding it into a lens shape after polymerization and hydrating and swelling it are as detailed above. A monomer having a six-membered carbon ring is a compound that has at least one six-membered carbon ring in the molecule, and the six-membered carbon ring includes polycyclic rings, regardless of whether they are saturated or unsaturated. . These compounds have an ethylenically unsaturated bond for copolymerization with the main components, hydroxyalkyl methacrylate or acrylate and unsaturated carboxylic acid. Examples of the six-membered carbon ring-containing compound include styrene, vinyltoluene, benzyl methacrylate, benzyl acrylate, cyclohexyl methacrylate, cyclohexyl acrylate, α-methylstyrene, etc., but typical examples include styrene, benzyl methacrylate, and α-methylstyrene. . If the amount of the monomer containing a six-membered carbon ring is less than 1 part by weight per 100 parts by weight of the mixture of HEMA and unsaturated carboxylic acid, no significant effect will be obtained, and if it is more than 10 parts by weight, the soft contact lens product will be affected. This is not preferable because it causes a decrease in the moisture content of the water. According to this improved method, restrictions on raw material composition and polymerization conditions due to the occurrence of opalescent phenomenon after hydration swelling treatment are eliminated, making it possible to achieve a sufficiently high water content with a desired composition. . Examples of the present invention are shown below. "%" in examples
"% by weight" and "parts" indicate "parts by weight." Example 1 0.5 parts of itaconic acid and 0.3 parts of divinylbenzene per 100 parts of a mixture consisting of 90% HEMA and 10% MAA.
1 part of water, and 0.1 part of azobisisobutyronitrile were thoroughly mixed and placed in a test tube, and a polymerization reaction was carried out at 65°C for 40 hours. After reaction, remove from test tube and
The rod-shaped polymer obtained by drying at ℃ for 48 hours was colorless and transparent, and was relatively hard and could be easily cut and polished. A soft contact lens with a water content of 80% that was hydrated and swollen by immersing the lens-shaped polymer in a physiological saline solution at 70°C and leaving it for 16 hours was obtained. This lens showed no opalescent phenomenon in the swollen state and its optical properties were sufficiently satisfactory. Comparative Example 1 For comparison with Example 1, an experiment was conducted under the same conditions except that water was not added. The obtained polymer was colorless and transparent and had good optical properties, but when hydrated and swollen under the same conditions, the water content was 40%.
It was hot. Example 2 Soft contact lenses obtained in Example 1, 70 parts of NVP made as a comparative example, and HEMA20
and a NVP soft contact lens made of 10 parts of MMA, and apply paste mascara on both parts.
It was fixed under running water and left for 10 minutes. In the NVP soft contact lens, mascara remained attached to more than half of the lens surface, whereas in the soft contact lens obtained in Example 1, the mascara was completely washed off. Example 3 0.5 parts of itaconic acid, 0.3 parts of ethylene glycol dimethacrylate, 1 part of water, and 0.1 parts of benzoyl peroxide were thoroughly mixed with 100 parts of a mixture consisting of 90% HEMA and 10% MAA, placed in a test tube, and heated at 65°C.
The polymerization reaction was carried out for 40 hours. After the reaction, the rod-shaped polymer obtained by taking it out from the test tube and drying it at 90°C for 48 hours was colorless and transparent, and was relatively hard and could be easily cut and polished. By immersing a polymer molded into a lens shape in a physiological saline solution at 70°C and leaving it for 16 hours, a soft contact lens with a water content of 80% due to hydration and swelling was obtained, but due to the condition of light rays. As a result, a milky white phenomenon appeared. Example 4 An experiment was conducted under the same conditions as in Example 3, except that 3 parts of a monomer having a six-membered carbon ring shown in Table 1 was further added to the polymerization raw material composition of Example 3. As shown in Table 1, the addition of these compounds was able to prevent the opalescent phenomenon. Although the water content of the obtained soft contact lens decreased by several percent, the optical properties were good.

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Claims (1)

[Claims] 1. 90 to 99% by weight of hydroxyalkyl methacrylate or acrylate, 1 to 10% by weight of unsaturated carboxylic acid having one ethylenically unsaturated bond.
0.1 to 2 parts by weight of a crosslinking agent and 0.1 to 10 parts by weight of water are added to 100 parts by weight of a mixture consisting of the following: polymerized, molded into a lens shape, and then hydrated and swollen. Method of manufacturing soft contact lenses. 2 The hydroxyalkyl methacrylate is 2
-Hydroxyethyl methacrylate.The method for producing a high water content soft contact lens according to claim 1. 3. Claim 1 or 2, wherein the unsaturated carboxylic acid is methacrylic acid and itaconic acid.
A method for producing a high water content soft contact lens as described in . 4. Claim 1, wherein the crosslinking agent is at least one compound selected from polyfunctional monomers.
A method for producing a high water content soft contact lens according to any one of items 1 to 3. 5 The polyfunctional monomer is divinylbenzene, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate,
The method for producing a high water content soft contact lens according to claim 4, which is allyl methacrylate, allyl acrylate, diallyl succinate, divinyl succinate, trimethylolpropane trimethacrylate, diallyl phthalate, and diethyl phthalate. 6 80 to 98% by weight of hydroxyalkyl methacrylate or acrylate, 1 to 10% by weight of an unsaturated carboxylic acid having one ethylenically unsaturated bond, and 1 to 10% by weight of a monomer having a six-membered carbon ring that can be copolymerized with these. %, 0.1 to 2 parts by weight of a crosslinking agent and 0.1 to 10 parts by weight of water are polymerized, formed into a lens shape, and then swelled by hydration. Method for manufacturing soft water content contact lenses. 7 The hydroxyalkyl methacrylate is 2
-Hydroxyethyl methacrylate.The method for producing a high water content soft contact lens according to claim 6. 8 Claim 6 or 7, wherein the unsaturated carboxylic acid is methacrylic acid and itaconic acid.
A method for producing a high water content soft contact lens as described in . 9 The monomer having a six-membered carbon ring is styrene,
The high water content software according to claims 6 to 8, which is at least one compound selected from the group consisting of vinyltoluene, benzyl methacrylate, benzyl acrylate, cyclohexyl methacrylate, cyclohexyl acrylate, and α-methylstyrene. Method of manufacturing contact lenses. 10. The method for producing a high water content soft contact lens according to any one of claims 6 to 9, wherein the crosslinking agent is at least one compound selected from polyfunctional monomers. 11 The polyfunctional monomer is divinylbenzene,
Ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, allyl methacrylate, allyl acrylate, diallyl succinate, divinyl succinate, trimethylolpropane trimethacrylate, 11. The method for producing a high water content soft contact lens according to claim 10, wherein diallyl phthalate or diethyl phthalate is used.