JPH0682177B2 - Hydrous contact lens - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel hydrous contact lens.

[Prior art]

Conventionally, various hydrous contact lenses have been known, and among them, those having a water content of about 40% containing 2-hydroxyethyl methacrylate as a main component are most widely used.

However, since this type of hydrous contact lens does not have sufficient oxygen permeability to supply the oxygen amount required for the cornea physiologically, it has a drawback that it cannot be worn continuously for a long time, Wearing beyond the limit is not preferable because it causes a corneal disorder and the like.

For this reason, various water-containing contact lenses have been studied in an attempt to increase the water content and supply the amount of oxygen required for corneal physiology from the atmosphere to the cornea through water in the contact lens material.

Among them, the most common material is N-vinyl-2
-Pyrrolidone (hereinafter referred to as N-VP) as a main component, and an alkyl ester of methacrylic acid or acrylic acid,
For example, it is a copolymer obtained by copolymerizing methyl methacrylate and the like. A high water content contact lens made of such a copolymer usually has a water content of about 50 to 80%, and generally, the oxygen amount required for the cornea is supplied to the cornea from the atmosphere through the water in the contact lens. Is possible.

However, such a copolymer has a large difference in the polymerizability between the N-vinyl group possessed by N-VP and the methacryloyl group and acryloyl group possessed by the alkyl ester of methacrylic acid or acrylic acid. And methacrylic acid or a polymer of an alkyl ester of acrylic acid are liable to phase-separate, which results in a decrease in transparency when water is contained and a lack of satisfactory mechanical properties.

On the other hand, JP-A-60-22926 discloses that a hydrous hydrogel can be obtained by using N-methyl-3-methylene-2-pyrrolidone (hereinafter referred to as N-MMP) and can be applied to a contact lens. However, as is clear by comparing Example 1 and Comparative Example 1 of the above-mentioned publication, it is easy to form a rigid polymer by using N-VP in order to obtain a material having a medium water content of about 50%. A flexible polymer can be obtained by using N-MMP. However, when trying to obtain a material having a high water content of about 70% or more, the suppleness of the polymer of N-MMP becomes conversely stiff, and the N-MMP polymer becomes N-hydrophilic as a hydrophilic monomer.
-When MMP is used in a large amount, there is a drawback that it becomes a contact lens with poor shape retention.

[Problems to be solved by the invention]

An object of the present invention is to improve the above-mentioned drawbacks and provide a contact lens having a high water content as well as excellent shape stability, mechanical properties and transparency.

[Means for solving problems]

That is, the present invention relates to (a) 40 to 85 parts by weight of N-vinyl-2-pyrrolidone and (b) 5 to 20 parts by weight of N-methyl-3-based on 100 parts by weight of the total amount of the non-crosslinking monomer. Methylene-2-
Pyrrolidone, (c) 5 to 20 parts by weight of N, N-dimethylacrylamide,
And (d) 5 to 40 parts by weight of alkyl acrylate and / or alkyl methacrylate, wherein the alkyl group has 1 to 3 carbon atoms and the alkyl group has 8 carbon atoms.
The present invention relates to a contact lens made of a copolymer of a monomer mixture including a mixture of 18 to 18.

N-VP used in the present invention is a monomer used for obtaining a material having a high water content. However, since the mechanical strength is lowered when trying to increase the water content, in the present invention, the water content is higher than that of N-VP. This is solved by copolymerizing N, N-dimethylacrylamide (hereinafter referred to as DMAA), which gives a polymer having a high molecular weight. However, if a large amount of DMAA is used, the softening point of the copolymer is lowered and so-called "burn-in" occurs, which makes cutting difficult, and polishing is also difficult.Therefore, the use of DMAA is limited. was there. Further, in order to maintain mechanical strength, a reinforcing component is required, and it is common to use an alkyl (meth) acrylate for such a reinforcing component, but N-VP, DMAA, alkyl (meth) The acrylate copolymer tends to become cloudy when it contains water, and the problem has not been completely solved.

In the present invention, these problems could be solved by further using N-MMP.

The polymerizing group of N-MMP is adjacent to the carbonyl group in the amide group, and is very similar to N, N-di (meth) acrylamide, so it has good copolymerizability with alkyl (meth) acrylate and DMAA and is macroscopic. It is a monomer that does not cause phase separation, that is, it gives a polymer with good transparency when it contains water.
Is reliably cross-linked, and there is an effect of preventing unpolymerized or low-polymerized DMAA from being eluted from the contact lens. Further, it is also a monomer that gives a polymer having excellent flexibility and elongation.

However, when N-MMP is used in a large amount, it becomes too supple and becomes a material having poor shape retention in a high water content region (water content of about 70% or more), so the amount used is naturally limited.

Therefore, in the present invention, the DMAA, N-MMP, and the reinforcing component are used in order to exert their effectiveness, relative to 100 parts by weight of the total amount of the non-crosslinkable monomer (hereinafter, "parts by weight" unless otherwise specified. It is necessary to use at least 5 parts by weight based on 100 parts by weight of the total amount of non-crosslinkable monomers. Also N-MMP
When it is used in excess of 20 parts by weight, it becomes a material having no shape retention (so-called "stiffness"), and when it is used in excess of 20 parts by weight, the softening point becomes low and the machinability becomes low. Furthermore, if the reinforcing component is used in an amount of more than 40 parts by weight, the water content becomes too low. Therefore, N-VP is 40 to 85 parts by weight, N-MMP is 5 to 20 parts by weight, and DMAA is 5 to 20 parts by weight. Parts, the reinforcing monomer is used in the range of 5 to 40 parts by weight,
Especially, N-MMP is preferably used in the range of 15 to 18 parts by weight.

Alkyl (meth) acrylate is preferably used as the reinforcing component in the present invention, and in order to enhance the reinforcing effect, an alkyl (meth) acrylate having 1 to 3 carbon atoms in the alkyl group (hereinafter referred to as A component) and alkyl A mixture of alkyl (meth) acrylates having 8 to 18 carbon atoms in the group (hereinafter referred to as component B) is used.

Specific examples of the component A include methylmethacrylate, ethylmethacrylate, n-propylmethacrylate, isopropylmethacrylate, and acrylates corresponding thereto, and one or more of them are selected and used. On the other hand, specific examples of the B component include, for example, octyl methacrylate, nonyl methacrylate,
Decyl methacrylate, dodecyl methacrylate, tridecyl methacrylate, octadecyl methacrylate,
Examples thereof include 2-ethylhexyl methacrylate, cyclohexyl methacrylate, trimethylcyclohexyl methacrylate, bornyl methacrylate, and acrylates corresponding to these. One or more of these are selected and used.

The ratio of the A component to the B component is preferably 1: 3 to 3: 1 by weight, because if the A component is too much, the reinforcing effect is lowered, and if the B component is too much, the water content is lowered.

From the viewpoint of stabilizing the shape of the hydrous contact lens of the present invention and improving the solvent resistance, it is also possible to use an ordinary crosslinkable monomer. Examples of the crosslinkable monomer include ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, vinyl methacrylate, allyl methacrylate, trimethylolpropane trimethacrylate, and the corresponding ones. Acrylate, divinylbenzene, N-vinyl-3-methylene-2-pyrrolidone, etc. are used, but when a large amount of a crosslinkable monomer is used, the water content is lowered, and the elongation rate is reduced. Usage is 5
It is preferably not more than parts by weight.

In the present invention, it is also possible to copolymerize a monomer other than the above. Examples of such a monomer include hydrophilic (meth) acrylates such as 2-hydroxyethyl methacrylate, 2-hydroxybutyl methacrylate, 2-methoxyethylene glycol methacrylate, and corresponding acrylates, trifluoroethyl methacrylate, and hexafluoroisopropyl methacrylate. , And fluoroalkyl (meth) acrylates such as acrylates corresponding to these.

In the polymerization, a usual polymerization initiator, for example, azobisisobutyronitrile, azobisdimethylvaleronitrile,
t-Butyl hydroperoxide, cumene hydroperoxide, benzoyl peroxide, acetyl peroxide, di-t-butylazodicyclohexylcarbonitrile, dimethyl azodiisobutyrate, succinic acid peroxide, etc. can be used. About 0.0 for 100 parts by weight of all monomers
It is in the range of 01 to 5 parts by weight, preferably about 0.01 to 2 parts by weight.

The polymerization method may be either ordinary bulk polymerization or solution polymerization. In the case of solution polymerization, it is preferable to use a solvent that can dissolve all the monomers used for the polymerization, such as acetonitrile, N-methylpyrrolidone, dimethylsulfoxide, dimethylformamide, ethanol and methanol. In any of the polymerization methods, a heating method, for example, heating polymerization at about 40 ° C to 50 ° C for several to several tens of hours and then heating at a rate of about 10 ° C / several hours to complete the polymerization. Preferably.

The above polymerization can be performed in a molding die having a shape corresponding to a desired contact lens shape to obtain a contact lens having a desired shape, or a contact lens can be molded by machining such as cutting and polishing. By hydrating and swelling the obtained molded product, a target hydrous contact lens can be obtained.

〔The invention's effect〕

The hydrous contact lens thus obtained is a high water content contact lens excellent in transparency and mechanical workability.
In addition, the rubber hardness is also high, so it has excellent shape retention.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the examples.

(Example 1) N-VP55 parts by weight and N-MMP13 were added to a polypropylene test tube.
Parts by weight, DMAA 12 parts by weight, methyl methacrylate (hereinafter MM
10 parts by weight, dodecyl methacrylate (hereinafter referred to as LMA)
10 parts by weight), allyl methacrylate (hereinafter referred to as AMA) 0.5 parts by weight, and azobisisobutyronitrile (hereinafter referred to as AIBN) 0.1 parts by weight are mixed, and the mixture is kept in a constant temperature water bath at 40 ° C. for 36 hours at 50 ° C. 8 hours in a constant temperature water bath, and 4 hours at 50 ° C in a hot air circulation dryer, then the temperature is 1.
Every 5 hours, the temperature was raised by 10 ° C to 110 ° C to complete the polymerization.

Then take out the polymer from the polypropylene test tube,
After curing (strain removal) at 90 ° C. for 2 hours, machining was performed to obtain a sample.

When the physical properties of this sample were measured, the water content was 76.
0, linear swelling ratio 63.0, oxygen permeability coefficient 31.2, rubber hardness 14.5,
The punching strength was 65 and the elongation rate was 105 (thickness 0.266 mm).

The physical property measuring methods, conditions, units, etc. are shown below.

Moisture content ・ Measurement temperature: 20 ℃ ・ Unit:% ・ Calculation formula Equilibrium water content film weight = W1 Dry film weight = W2 Linear swelling rate ・ Measurement temperature: 20 ℃ ・ Unit:% ・ Calculation formula When film diameter when equilibrium water content = D1 and film diameter when dry = D2, Oxygen permeability coefficient ・ Measurement temperature: 35 ℃ ・ Unit: ・ Measuring instrument: A Kaken film oxygen permeability meter (manufactured by Rika Seiki Co., Ltd.) is used.

Punching load ・ Measurement temperature: Room temperature ・ Unit: g ・ Measurement method Using an Instron type compression tester, apply a 1/16 inch diameter pressing needle to the center of the water-containing film and measure the load at break. did.

Elongation rate ・ Measurement temperature: Room temperature ・ Unit:% ・ Measurement device Same as punching load (measured simultaneously). The amount of elongation up to break is calculated as a percentage.

Rubber hardness ・ Measurement temperature: 20 ℃ ・ Unit: degree ・ Measurement method Measured according to JIS K6130.

The polymer was cut and polished to form a contact lens, which was swollen with physiological saline to obtain a desired hydrous contact lens. The obtained contact lens was colorless and transparent and was satisfactory as a hydrous contact lens.

(Examples 2 to 5) The physical properties of the sample operated in the same manner as in Example 1 except that the compounding ratios are different are shown in Table 1 together with Example 1.

(Comparative Example 1) As a comparison, blending was performed without using N-MMP. That is, polypropylene test tube with N-VP53.3 parts by weight, DMAA
26.7 parts by weight, MMA10 parts by weight, LMA10 parts by weight, AMA0.5 parts by weight and AIBN0.1 parts by weight are mixed and placed in a constant temperature water bath at 40 ° C.
For 8 hours in a constant temperature water bath at 50 ° C., and further in a hot air circulation dryer, the temperature was raised to 110 ° C. by 10 ° C. every 1.5 hours for 4 hours and then at 50 ° C. to complete the polymerization.

Then take out the polymer from the polypropylene test tube,
After curing (strain removal) at 90 ° C. for 2 hours, machining was performed to obtain a sample.

The sample was hydrated and swollen and the appearance was observed, but it was a material showing a considerable amount of white turbidity.

Claims (1)

[Claims] 1. A total of 100 parts by weight of non-crosslinkable monomers, (a) 40 to 85 parts by weight of N-vinyl-2-pyrrolidone, and (b) 5 to 20 parts by weight of N-methyl-3-. Methylene-2-
Pyrrolidone, (c) 5 to 20 parts by weight of N, N-dimethylacrylamide,
And (d) 5 to 40 parts by weight of alkyl acrylate and / or alkyl methacrylate, wherein the alkyl group has 1 to 3 carbon atoms and the alkyl group has 8 carbon atoms.
A hydrous contact lens made of a copolymer of a monomer mixture including a mixture of -18.