JPS6251448B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a low water content contact lens, in which about 72 to 98 mol% of alkylene glycol monoacrylate or monomethacrylate, about 2 to 28 mol% of butyl methacrylate, and about 0.02 to 28 mol% of allyl methacrylate or allyl acrylate.
By constructing the contact lens with a copolymer obtained by polymerizing a composition containing 0.5 mol% so that the water content of the copolymer is about 20 to 38% by weight, it has high hydrophilicity and oxygen permeability. It is an object of the present invention to provide a low water content contact lens which can be made to have excellent wearability, has high tensile strength and elongation at break, is resistant to damage, and can be made thin. purpose. Conventionally, so-called soft contact lens materials have a main component of alkylene glycol methacrylate such as 2-HEMA, a subcomponent of methacrylic acid, and a crosslinking agent such as ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, or isocyanuric acid. Polymers polymerized using triallyl, divinylbenzene, allyl ether, etc. have been proposed. Soft contact lenses whose main ingredient is 2-HEMA etc. have good wettability due to the hydrophilic nature of 2-HEMA and are somewhat comfortable to wear, but this material does not have sufficient oxygen permeability. For example, it has the disadvantage that its oxygen permeability is much lower than that of silicone resin, so it cannot be worn continuously for a long period of time, and it is not comfortable to wear because it cannot supply sufficient oxygen to the cornea. There are some drawbacks. Therefore, we focused on the fact that even if contact lenses were made from the materials mentioned above, the oxygen permeability could be improved by making the contact lenses thinner, so we created thinner contact lenses. The above-mentioned materials have low tensile strength and elongation at break, and as a result, thin contact lenses are often damaged when handled, resulting in a new fatal drawback of extremely poor durability. Therefore, with conventional soft contact lens materials, only contact lenses with poor oxygen permeability can be obtained, making it impossible to wear them continuously for long periods of time, and furthermore, the thickness of the contact lenses is thick, making them uncomfortable to wear. . The inventor of the present invention investigated why conventional soft contact lens materials such as those mentioned above have low tensile strength, etc., and as a result of intensive research on this, the inventor found that approximately 72 to 98 mol of alkylene glycol monoacrylate or monomethacrylate was found. %, about 2 to 28 mol% of butyl methacrylate,
and a contact constructed using a copolymer obtained by polymerizing a composition containing allyl methacrylate or allyl acrylate in a proportion of about 0.02 to 0.5 mol% so that the water content of the copolymer is about 20 to 38% by weight. The lens is
Even if the thickness of the contact lens is made thinner, sufficient strength can be obtained, and since the thickness of the contact lens can be made thinner, the amount of oxygen permeation will be correspondingly larger. They discovered that highly durable contact lenses could be made. Examples of low water content contact lenses according to the present invention will be described below. Examples 1 to 7 and Comparative Examples 1 to 9 Approximately 93 parts by weight of 2-HEMA, approximately 7 parts by weight of n-butyl methacrylate, and the compounds listed in Table 1 were used as crosslinking agents, and a polymerization initiator, e.g. , 2'Azobis-2,4-dimethylvaleronitrile about 0.05 parts by weight was added to prepare a polymerization stock solution, and this polymerization stock solution was charged into a polypropylene polymerization tube with an inner diameter of 116 mm and a height of 300 mm, and the upper space was replaced with nitrogen gas. Seal tightly. Next, after photopolymerizing by irradiating ultraviolet rays at about 15℃ for about 10 hours,
Continuously raise the temperature to 100°C to complete the polymerization reaction. After cooling, a colorless and transparent polymer block is taken out from the polymerization tube, and a contact lens is made from this block by a predetermined cutting and polishing process. Comparative Examples 10, 11 In Example 5, vinyl acetate (Comparative Example 10) and vinyl propionate (Comparative Example 11) as proposed in JP-A-54-126054 were used instead of n-butyl methacrylate. and do the same. A sample piece with a thickness of 0.2 mm and a diameter of 15 mm was prepared from the polymer block obtained as described above, and the tensile strength and other properties of this sample piece were measured as shown in Table 1.

【table】

[Table] Example 8 and Comparative Examples 12 to 15 Using about 85 parts by weight of 2-HEMA, about 10 parts by weight of propylene glycol monomethacrylate, about 5 parts by weight of isobutyl methacrylate, and the compounds listed in Table 2 as crosslinking agents, these 2,2′- in the mixture
Azobis-2,4-dimethylvaleronitrile approx.
Add 0.05 parts by weight to obtain a polymerization stock solution, charge this polymerization stock solution into a polypropylene polymerization tube, replace the upper space with nitrogen gas, and then seal the tube. Then about 35
℃, heated to about 40℃ after about 20 hours, and further heated to about 3℃ at each temperature of about 60℃, about 80℃ and about 100℃.
The polymerization reaction is completed by holding for a certain period of time. After cooling, a colorless and transparent polymer block is taken out from the polymerization tube, and a contact lens is made from this block by a predetermined cutting and polishing process. A sample piece similar to that in the above example was prepared from the polymer block prepared as described above, and the tensile strength and other properties of this sample piece were measured as shown in Table 2.

[Table] As is clear from the above results, for example, 2-
Allyl methacrylate or allyl acrylate, especially methacrylate, is used as a crosslinking agent for those containing alkylene glycol monoacrylate or monomethacrylate as a main component such as HEMA, and butyl methacrylate such as n-butyl methacrylate or isobutyl methacrylate as a subcomponent. using allyl acid, and these alkyl glycol monoacrylate or monomethacrylate vs. butyl methacrylate vs. allyl methacrylate or allyl acrylate at 72 to 98 mol% vs. 2 to 28 mol%.
% to 0.02 to 0.5 mol% and the water content of the polymer is about 20 to 38% by weight.The polymer is polymerized with a crosslinking agent such as ethylene glycol dimethacrylate, triallyl isocyanurate, divinylbenzene or Its tensile strength and elongation at break are much better than allyl ether and other crosslinking agents conventionally used as crosslinking agents for soft contact lens materials. Therefore, since the material of the low water content contact lens according to the present invention is extremely strong, even if the thickness of the contact lens is made thinner, the thickness of the contact lens can be reduced to about 1% of the thickness of a conventional contact lens. Even if the contact lens is made as thin as /3, it will still be sufficiently durable, and even if the contact lens is thin, it will not be easily damaged when handled. In addition, by reducing the thickness of contact lenses, the amount of oxygen permeation increases, and therefore more oxygen can be supplied to the cornea, making it possible to wear them continuously for long periods of time. Due to its thinness, there is less of a foreign body sensation when it is worn on the eye, resulting in a much better wearing experience. The amount of allyl methacrylate and allyl acrylate added is about 0.02 to 1 mol%, particularly preferably about 0.2
~0.5mol%. As the amount of added allyl methacrylate increases to a certain extent, the tensile strength increases and the product becomes more durable, but beyond a certain limit, the tensile strength begins to decrease, and soft contact lenses When handling contact lenses, they are sterilized by boiling. Therefore, when measuring the base curve stability of contact lenses under boiling conditions, if the amount of allyl methacrylate added is too small, the base curve of contact lenses will change due to boiling. This is because the lens changes and becomes unable to fulfill its role as vision correction. In addition, the amount of butyl methacrylate added is about 2 to
It was found that 28 mol% is desirable. This is because, for example, if the amount of butyl methacrylate such as n-butyl methacrylate is increased, the tensile strength becomes relatively large, but if the amount of methacrylic acid ester is too large, the flexibility of the contact lens becomes poor even when it contains water. This is because contact lenses become less comfortable to wear. In addition, as monoacrylate or monomethacrylate of alkylene glycol, 2-
In addition to HEMA and propylene glycol monomethacrylate, there are monomethacrylates or monoacrylates such as diethylene glycol, tetraethylene glycol, or polyethylene glycol, and similar effects can be obtained. In addition, since the low water content contact lens of the present invention has a water content of about 20 to 38%, unlike contact lenses with high water content, the swelling rate is small, making it difficult to predict dimensions such as base curve and diameter. It is easy to process, so it is easy to process contact lenses with accurate base curves, etc. Also, since the adsorption property is not large, it is difficult to adsorb proteins and fats in tear fluid, so contact lenses is not easily soiled. Furthermore, since the low water content contact lens of the present invention is made of a hydrophilic material, it has good wettability with water and is therefore comfortable to wear. As mentioned above, the low water content contact lens according to the present invention contains about 72 to 98 mol% of alkylene glycol monoacrylate or monomethacrylate, and about 2 to 28 mol% of butyl methacrylate.
and a composition containing allyl methacrylate or allyl acrylate in a proportion of about 0.02 to 0.5 mol%, using a copolymer polymerized so that the water content of the copolymer is about 20 to 38% by weight. Therefore, contact lenses are highly tough with excellent properties such as tensile strength and elongation at break, and therefore are sufficiently durable even when thinned, and by making contact lenses thinner, they are more durable for the eyes. When worn, it does not feel like a foreign body, and has good oxygen permeability, making it even more comfortable to wear and allowing continuous wear for a long time.Furthermore, it has good water resistance, making it even more comfortable to wear. Also, since the base curve is highly stable, it has features such as good vision correction.

Claims (1)

[Claims] 1 About 72 to 98 mol% of alkylene glycol monoacrylate or monomethacrylate,
Approximately 2 to 28 mol% butyl methacrylate and approximately 0.02 allyl methacrylate or allyl acrylate
1. A low water content contact lens, characterized in that it is constructed using a copolymer obtained by polymerizing a composition containing a composition in a proportion of ~0.5 mol% such that the water content of the copolymer is approximately 20 to 38% by weight.