JP2008065289A - Water-containing contact lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-containing soft contact lens that is excellent in shape stability even in a water-containing state in spite of high water content, that has high toughness, therefore, is hardly brittle to break, and that achieves excellent handling property. <P>SOLUTION: The water-containing contact lens is obtained by polymerizing copolymerization components including (A) 2-hydroxyethyl(meth)acrylate, (B) (meth)acrylic acid, (C) (meth)acrylate having a glass transition temperature of the homopolymer of 0°C or lower, and (D) polyethylene glycol di(meth)acrylate having 4 to 12 ethyleneglycol units. The contact lens supplies sufficient oxygen to a cornea because of high water content; the lens shows not only excellent transparency but improvement in the tendency of being brittle and easily breaking, which is a problem of a lens having high water content; and the lens has enough mechanical strength durable for practical use. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydrous soft contact lens, and in particular it has excellent shape stability even in a hydrous state even though it is highly moist, and it has high toughness, so it is less likely to break and is easy to handle. The present invention relates to a hydrous soft contact lens.

  Current hydrous soft contact lenses can be broadly classified into three types. One is a soft contact lens having a relatively low water content obtained by using 2-hydroxyethyl methacrylate (hereinafter referred to as HEMA) as a main component, and the other is N-vinyl-2-pyrrolidone ( HEMA and methacrylic acid (hereinafter referred to as MA), which are non-ionic high water content lenses mainly composed of NVP) and N, N-dimethylacrylamide (hereinafter referred to as DMA), and which have become mainstream disposable lens materials in recent years. Is an ionic high water content lens.

  The HEMA contact lens has a high rubber hardness, so it is difficult to fit the eyeball, but it is not as hard as a hard lens, but lacks good wearing feeling, and its moisture content is low, so that the oxygen supply to the cornea is compensated. There is a problem that it must be processed very thinly. In addition, a high water content lens mainly composed of NVP / DMA has sufficient strength by simply copolymerizing with methyl methacrylate (hereinafter referred to as MMA), which is used as a contact lens material, simply as a hydrophobic monomer for lens reinforcement. Since it cannot be applied, a macromer as a reinforcing component is separately prepared or an interpenetrating network structure with the MMA polymer is formed, so that the mechanical strength of the lens is given and the usability is improved. However, separately preparing the macromer and polymer leads to an increase in cost, and due to the nature of the macromer, the crease attached to the lens is difficult to return to its original state by pinching when removing the lens to increase the rubber hardness of the lens. There is a problem. Furthermore, HEMA and MA-based ionic lenses are very flexible but do not have sufficient shape retention, and it is difficult to keep the lens shape stable when placed on the fingertip when wearing the lens. There is a problem of using nerves when handling.

  By the way, in this HEMA and MA ionic lens, the water content of the homopolymer of HEMA alone is 40% at most, but the water content is 60% or more only by adding about 2% by weight of MA. Will come to show. In combination with conventional HEMA, MA is used at 5% by weight or less, for example, about 2% by weight in Japanese Patent Laid-Open No. 2-219831, and 2.9% by weight or less in Japanese Patent Laid-Open No. 62-127711. Stay on. The reason for this is that although the moisture content can be easily increased by adding MA, the higher the moisture content, the smaller the proportion of the polymer component in the lens, and the higher the glass transition temperature of the constituent polymer, which is hard but tough. As a result, it is considered that the main reason is that the entire lens is brittle and easily broken (a state like a so-called agar gel).

  On the other hand, as an example of using (meth) acrylic acid monohydric alcohols and esters of polyhydric alcohols as a material for contact lenses, there is JP-A-8-292404. This document describes a polyurea network and A contact lens constructed by interpenetrating a polyacrylic network is produced. However, this publication does not describe or suggest the use of the ester in combination with HEMA or MA.

  Japanese Patent Laid-Open No. 2-219831   Japanese Patent Laid-Open No. 62-127711   JP-A-8-292404

  Here, the present invention has been made in the background of the above-mentioned circumstances, and the problem to be solved is excellent shape retention even if the moisture content is increased to improve oxygen permeability. An object of the present invention is to provide a contact lens having mechanical strength that can withstand practical use by improving the conventional tendency of being brittle and fragile as well as excellent transparency.

  That is, the present invention includes (A) 2-hydroxyethyl (meth) acrylate (B) (meth) acrylic acid, (C) (meth) acrylate having a glass transition temperature of 0 ° C. or less, and (D) ethylene glycol. The present invention relates to a hydrous soft contact lens made of a copolymer obtained by polymerizing a copolymer component containing polyethylene glycol di (meth) acrylate having 4 to 12 units.

［式中、ｎは１〜９の整数であり、Ｒ_１は水素もしくはメチル基、Ｒ_２は炭素数１〜２０のアルキル］
で表される（メタ）アクリレートが好ましく用いられ、より好ましくはエトキシエチルメタクリレートである。In the present invention, the component (C) is represented by the following formula (1):

[Wherein, n is an integer of 1 to 9, R ₁ is hydrogen or a methyl group, and R ₂ is alkyl having 1 to 20 carbon atoms]
The (meth) acrylate represented by these is used preferably, and more preferably is ethoxyethyl methacrylate.

  Further, although the component (D) is a cross-linking agent component, it is desirable to use an appropriate length in order to give the lens toughness even with a high water content. In the present invention, nanoethylene glycol dimethacrylate is preferred. Used.

  The components (A) are 60 to 85% by weight, the components (B) are 8 to 18% by weight, the components (C) are 5 to 15% by weight, and the components (D) are 0.01 to 2%. By using it in the range of 0% by weight, the high water content contact lens of the present invention can be obtained.

  (A) 2-hydroxyethyl (meth) acrylate of the present invention, (B) (meth) acrylic acid, (C) (meth) acrylate having a glass transition temperature of 0 ° C. or less, and (D) ethylene glycol unit. A hydrous contact lens obtained by polymerizing a copolymer component containing 4 to 12 polyethylene glycol di (meth) acrylate supplies sufficient oxygen to the cornea due to its high water content, and of course has excellent transparency. It is possible to provide a hydrous soft contact lens having mechanical strength that can withstand practical use by improving the tendency to become brittle and fragile, which is a problem with lenses having a high water content.

Hereinafter, the present invention will be specifically described.
In the present invention, the glass transition of a homopolymer to the combination of 2-hydroxyethyl (meth) acrylate and (meth) acrylic acid, which is a conventionally known combination, for the purpose of reducing the rubber hardness of the polymer and improving the brittleness. (Meth) acrylate having a temperature of 0 ° C. or lower was added, and polyethylene glycol di (meth) acrylate having 4 to 12 ethylene glycol units was added for the purpose of giving stretchability to the distance between molecular chains of the polymer. There is a feature.

  (A) 2-hydroxyethyl (meth) acrylate used in the present invention is the main component of the polymer and forms the basic skeleton of the contact lens constituting polymer. Further, since the polymer itself is hydrophilic and has good compatibility with living tissue, it is also the earliest hydrous soft contact lens material.

  The blending amount of the 2-hydroxyethyl (meth) acrylate gives moderate hydrophilicity and rubber hardness to the contact lens obtained as the main component of the lens material of the present invention. More preferably, the content is adjusted to 65% by weight or more. Further, if the amount of the component is too large, the ratio of other monomer components is relatively reduced, and the moisture content becomes too low or the rubber hardness becomes too high. % Or less, preferably 80% by weight or less.

  (B) (Meth) acrylic acid used in the present invention is a component that further improves the moisture content of the contact lens, and is also known in the prior art as a monomer that dramatically increases the moisture content in a small amount. Conventionally, the monomer has been used in an appropriate amount of about 3% by weight, and the water content of contact lenses has been around 60%. Of course, it is well recognized by those skilled in the art that the moisture content can be increased by increasing the component ratio of the monomer (for example, exceeding 5% by weight). For example, disposable diapers are also used as superabsorbent polymers. However, the reason that the ratio of the monomer was not increased in the contact lens is that the brittleness of the lens obtained when the water content becomes too high is considered to be remarkable. During handling, the soft contact lens is removed while being pinched with a fingertip when it is removed from the wearer's eye, but if the lens is not flexible at that time, chipping or tearing is likely to occur. Since the copolymer composed of 2-hydroxyethyl (meth) acrylate and (meth) acrylic acid is inferior in toughness, it is likely to cause practical problems when the water content is increased to a high level, and the ratio of (meth) acrylic acid is large. Then it was not used.

  In the present invention, the components (C) and (D), which will be described later, are configured such that even if the ratio of (meth) acrylic acid is increased, the lens is not brittle and easily broken. The blending amount of (meth) acrylic acid can be 8% by weight or more, more preferably 10% by weight or more, depending on the circumstances. As a result, it is possible to obtain a lens having a high water content of 80% or more, which is considerably higher than the water content of the conventional contact lens. Further, if the amount of (meth) acrylic acid is too large, the water content increases, but the mechanical strength cannot be sufficiently exhibited because the ratio of the polymer decreases, so that the total amount of copolymerization components is 18% by weight or less, Preferably, it should be used at 16% by weight or less.

  The (C) homopolymer (meth) acrylate having a glass transition temperature of 0 ° C. or lower used in the present invention is a component for imparting toughness while maintaining the water content of the soft contact lens. The blending amount is 5% by weight or more, preferably 7% by weight or more. This is because when the amount of this component is small, it becomes difficult to impart sufficient toughness to the high water content lens that has been increased by (meth) acrylic acid, and therefore, it tends to be damaged. When the amount is too large, the content is adjusted to 15% by weight or less, preferably 13% by weight or less in order to act in the direction of lowering the moisture content.

More specifically, the (C) component is preferably a (meth) acrylate represented by the following formula (1).

[Wherein, n is an integer of 1 to 9, R ₁ is hydrogen or a methyl group, and R ₂ is alkyl having 1 to 20 carbon atoms]

  The (meth) acrylate represented by the chemical formula is an ester of monohydric alcohols and polyhydric alcohols of (meth) acrylic acid, and has an ethyleneoxy group in the structural formula. This improved the hardness of the lens material composed of 2-hydroxyethyl (meth) acrylate and (meth) acrylic acid without reducing the hydrophilicity of the resulting lens, and applied a slight impact and destructive force. Even in this case, the lens is imparted with toughness that does not easily cause damage or damage. As the (meth) acrylate represented by the previous formula, ethylene glycol (meth) acrylate, diethylene glycol (meth) acrylate, triethylene glycol (meth) acrylate, methoxyethylene glycol (meth) acrylate, ethoxyethylene glycol (meth) acrylate, ... is raised. Among these, ethoxyethylene glycol (meth) acrylate is preferable in terms of availability, cost, and polymerizability with other copolymerization components.

  The (D) polyethylene glycol di (meth) acrylate having 4 to 12 ethylene glycol units used in the present invention is a component that functions as a cross-linking agent. In particular, the distance between the cross-linking points of the constituent polymers is set at an appropriate interval. Hold. This cross-linking agent widens the space between the main chain polymers by the chain length of the ethylene glycol chain as compared with the conventionally used ethylene glycol di (meth) acrylate. Thus, mechanical strength is imparted to the lens material while realizing a higher water content. If the ethylene glycol chain is too long, a problem is likely to occur in the shape stability of the lens. Therefore, the range of 4 to 12 is preferable. As the component, nonaethylene glycol di (meth) acrylate having 9 ethylene glycol units is particularly preferable.

  The blending amount of the component (D) is 0.01% by weight or more, more preferably 0.05% by weight or more. This is because if the amount of the component is too small, the decrease in the crosslinking point directly affects the decrease in mechanical strength, causing a problem in practical use of the obtained lens. If it is too much, the crosslinking point increases and the hardness of the lens increases, surface water repellency occurs, and it becomes brittle and easily broken, so it is adjusted to 2.0% by weight or less, more preferably 1.8% by weight or less. Is done.

  As described above, the contact lens of the present invention has (A) 2-hydroxyethyl (meth) acrylate, (B) (meth) acrylic acid, (C) a (meth) acrylate having a glass transition temperature of 0 ° C. or less, (D) It is obtained from a copolymer obtained by polymerizing a copolymer component containing polyethylene glycol di (meth) acrylate having 4 to 12 ethylene glycol units, but does not impair the purpose and effect of the present invention. In addition to these, other monomer components capable of copolymerization can be used.

  For example, when an appropriate hardness is imparted to the obtained contact lens to improve the workability at the time of cutting, an alkyl methacrylate such as methyl methacrylate, ethyl methacrylate, or propyl methacrylate can be used. Since these are inherently hydrophobic monomers, if they are incorporated too much, there is a tendency that the objective high water content lens of the present invention cannot be obtained. Therefore, it is 10% by weight or less, preferably 7% by weight of the total amount of copolymerization components. It is desirable to adjust to% or less.

  In addition to N-vinyl-2-pyrrolidone and N, N-dimethylacrylamide as hydrophilic monomer components used in ordinary hydrous contact lenses, 1-methyl-3-methylene-2-pyrrolidone, 1-methyl Pyrrolidone derivatives such as -5-methylene-2-pyrrolidone, N-substituted acrylamides such as N, N-diethylacrylamide, N-isopropylacrylamide, N- (2-hydroxyethyl) acrylamide, hydroxypropyl (meth) acrylate, hydroxybutyl It is also possible to add hydroxyalkyl (meth) acrylates such as (meth) acrylates. These can be used as a monomer component that substitutes a part of the components (A) and (B) of the present invention as a hydrophilic monomer component. However, pyrrolidone derivatives and N-substituted acrylamides are useful for maintaining the water content, but tend to reduce the rubber hardness of the lens. If used in large quantities, the lens shape retention may be inferior. It is desirable to adjust the total amount to 10% by weight or less, preferably 7% by weight or less.

  Furthermore, since the refractive index of the lens decreases as the water content increases, the lens thickness tends to increase for patients with severe vision correction. Therefore, the addition of alkyl styrene such as styrene, α-methyl styrene, ethyl styrene, propyl styrene, or t-butyl styrene can prevent the reduction of refractive power. Moreover, it is also possible to mix | blend suitably according to a use and the objective, such as the polymeric ultraviolet absorber for providing a lens with ultraviolet absorptivity, and the polymeric dye for coloring of a lens.

  In addition, a radical polymerization initiator and a photopolymerization initiator are added to the copolymerization component blended based on the present invention in order to start polymerization of the monomer.

  Examples of the radical polymerization initiator include azobisisobutyronitrile, azobis (2,4-dimethylvaleronitrile), and benzoyl peroxide. Examples of the photopolymerization initiator include benzoin, benzoin methyl ether, Examples include 2,2-dimethoxy-2-phenylacetophenone and benzophenone. One or more of these initiators can be selected and used, and the amount used is preferably about 0.001 to 1% by weight of the total amount of the copolymer components.

  The copolymerization component blend thus prepared is poured into, for example, a glass tube or a polypropylene tube, polymerized by heating at about 25 to 45 ° C. for several hours to several tens of hours, and then about 120 ° C. The desired lens is obtained by adopting a method in which the temperature is gradually raised until the polymerization is completed and a method of processing into a lens shape by cutting and polishing or a mold polymerization method in which a mold having a lens-shaped space is filled to complete the polymerization be able to.

  In the polymerization, in addition to the case of heat polymerization, a method of performing photopolymerization using the photoinitiator, a method of performing polymerization by combining heat polymerization and photopolymerization, and the like can be mentioned. In the polymerization in the present invention, the bulk polymerization method has been mainly described, but it is also possible to perform polymerization by adding a solvent as necessary. In particular, when the polymerization is completed by filling the mold, bubbles or defects may occur in the lens obtained by the polymerization shrinkage. In such a case, it is preferable to compensate for the polymerization shrinkage by adding a solvent. .

  Next, after the obtained contact lens is swollen in physiological saline, the intended hydrous soft contact lens can be obtained by neutralizing (meth) acrylic acid with an alkali. As a specific method, it can be performed by immersing in a 0.5% aqueous sodium carbonate solution and heating at about 60 ° C. for about 10 to 30 minutes. Repeat the same operation 3 times by immersing in 15 mL per plate for 5 minutes) and finally replacing with physiological saline. In this case, by coexisting a reactive dye, the contact lens can be colored simultaneously with neutralization.

The water-containing soft contact lens of the present invention exhibits a high water content of 70% or more, thus sufficiently compensating for the shortage of oxygen supply to the cornea caused by wearing the lens. Easy to handle because of excellent stability. In addition, because the lens is brittle and improved in toughness, the lens is not easily chipped or torn even in the event of an unexpected impact during handling, and has sufficient mechanical strength in practical use. Is.
Hereinafter, in order to clarify the present invention more specifically, some examples of the present invention will be described.

  84.06% by weight of 2-hydroxyethyl methacrylate (Wako Pure Chemical Industries, Ltd .: Wako First Grade), 5.9% by weight of methacrylic acid (Wako Pure Chemical Industries, Ltd .: Wako Special Grade), ethoxyethyl methacrylate (Mitsubishi Rayon Co., Ltd.) Product name: Acryester ET) 8.9% by weight, nonaethylene glycol dimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd .: product name 9G) 0.84% by weight, and azobis (2,4-dimethyl) as a polymerization initiator Valeronitrile) (manufactured by Wako Pure Chemical Industries, Ltd .: Wako Grade 1) was thoroughly mixed in an amount of 0.3% by weight, and after deaeration, it was filled into a contact lens mold made of polypropylene.

  Next, this mold was put into a temperature rising dryer, heated from room temperature to 60 ° C. over 30 minutes, and held at 60 ° C. for 1 hour. Further, the temperature was raised from 60 ° C. to 90 ° C. over 30 minutes, maintained at 90 ° C. for 1 hour, and then gradually cooled to room temperature.

  The obtained copolymer was immersed in a 0.5% aqueous sodium carbonate solution, heated at 60 ° C. for 15 minutes, taken out after immersion, and immersed in 15 mL of purified water for 5 minutes per lens, and the purified water Was discarded and immersed in the same amount of purified water. After immersion in purified water three times, the target contact lens was obtained by immersing in physiological saline.

  As the physical properties of the obtained water-containing soft contact lens, water content, rubber hardness, shape stability in a water-containing state, visible light transmittance, punching strength, and wearing feeling were examined according to the following methods. The results are shown in Table 1.

-Measurement method of moisture content-
After leaving the lens obtained in the above example in physiological saline at 25 ° C. for 12 hours, the lens was taken out, and the surface moisture was quickly wiped off with Kimwipe (manufactured by Jujo Kimberley Co., Ltd.). (Weight when wet, indicated as W (g)) was measured. Next, each sample lens was transferred into a dryer, dried at 80 ° C. for 2 hours, allowed to cool to room temperature, and then each weight (weight when dried, indicated as W ₀ (g)) was measured. The moisture content (% by weight) of each sample lens was calculated based on the formula. In Table 1, the average value of five samples is shown.

Water content (% by weight) = {(W−W ₀ ) / W} × 100

-Measuring method of rubber hardness-
The copolymer component was filled in a glass test tube and heated in a constant temperature water bath at 35 ° C. for 12 hours, 46 ° C. for 4 hours, and 55 ° C. for 4 hours. This was put into a temperature rising drier and kept at 60 ° C. for 1 hour. Further, the temperature was raised from 60 ° C. to 90 ° C. over 30 minutes, maintained at 90 ° C. for 1 hour, and then gradually cooled to room temperature. The obtained round bar is cut to prepare three disk-shaped test pieces having a diameter of about 12 mm and a thickness of 4.0 mm. This test piece was immersed in 50 mL of 0.5% aqueous sodium carbonate solution at room temperature for 1 week, taken out, and left in physiological saline 50 mL for 3 days. Thereafter, the physiological saline was exchanged and left for another 3 days, and the physiological saline exchange was performed three times. This was used as a water-containing sample and left at 20 ° C. for 12 hours. The rubber hardness was measured with a constant pressure loader GS-710 (manufactured by TECLOCK) in accordance with JIS K6301 “Physical Test Method for Vulcanized Rubber”. In Table 1, the average value of three samples is shown. Further, the rubber hardness of the commercially available lens was measured by stacking 30 lenses and increasing the thickness on the test piece, and used as a comparison object.

-Shape stability under water condition-
The specifications of the hydrous contact lens obtained by the method of Example 1 were a center thickness of 0.08 mm, a power of −3.00 D, and a base curve of 9.00 mm. When this water-containing soft contact lens is placed on the index finger and the shape of the complete contact lens can be maintained, the shape stability is good even in the water-containing state (indicated in the table by ○). The case where it stuck to the finger or could not maintain the sufficient shape of the contact lens was evaluated as defective (indicated as x in the table).

-Measurement of visible light transmittance-
A water-containing film having a diameter of about 12 mm and a thickness of 0.2 mm prepared in the same manner as the rubber hardness sample was prepared. About this water-containing film, the visible light transmittance (%) in the wavelength region of 380 to 780 nm was measured using a spectrophotometer (manufactured by SHIMADZU; UV-2450). Such measurement was performed in a quartz cell immersed in water.

-Punch strength test-
Using a punch strength tester (manufactured by Rheotech; RT-2005D · D), the measurement was performed as follows. Place a sample plate similar to the sample used for the visible light transmittance on a cylindrical base, and fix the periphery so that the specimen does not move, then press the round tip at the center of the plate with a diameter of 1 mm Place the needle and apply pressure to the other end to press the plate. The value (g / cm) obtained by dividing the weight value (g) when the plate was stretched and damaged by the load by the center thickness (cm) of the plate was used as the punching strength value. This measurement was performed on 10 plates, and the average value was shown in the table.

-Wearing feeling-
The contact lens obtained in Example 1 (the standard is the same as the shape stability test described above) was subjected to a cell / rabbit test to confirm sufficient safety, and then was worn by three male volunteers for 1 hour. When they were asked, none of them had a feeling of foreign matter, and it was confirmed that the soft contact lens had an excellent wearing feeling.

-Handling durability-
The contact lens obtained in Example 1 and a commercially available disposable contact lens (HEMA-MA system water content of about 60%) are rubbed back and forth and left and right while being pinched between the thumb and index finger until the lens breaks. The time was compared. As a result, it was found that even when a commercially available disposable lens was broken, the contact lens of the present invention was not damaged at all, and the contact lens of the present invention had sufficient mechanical strength for practical use.

(Examples 2-4 and Comparative Examples 1-3)
A contact lens was produced in the same manner as in Example 1 except that the composition was changed as shown in Table 1 in Example 1. Each physical property of the obtained contact lens was also examined in the same manner as in Example 1. The results are shown in the same table. In addition, the comparative example used the commercially available disposable contact lens.

Abbreviations in the table are as shown below.
HEMA: 2-hydroxyethyl methacrylate MA: methacrylic acid ET: ethoxyethyl methacrylate 9G: nanoethylene glycol dimethacrylate

  From the results shown in Table 1, the contact lens according to the present invention has excellent shape stability due to its high rubber hardness despite its very high water content of 70% or more, and mechanical strength such as punching strength. It can be seen that it has excellent characteristics.

  On the other hand, when the punching strength was measured using a commercially available disposable contact lens as a comparative example, the moisture content was lower than that of the contact lens of the present invention, but in terms of strength, it was the same level as the contact lens of the present invention. It can be seen that the contact lens of the present invention is at a level that can be sufficiently applied in the market.

Claims (4)

  (A) 2-hydroxyethyl (meth) acrylate, (B) (meth) acrylic acid, (C) (meth) acrylate having a glass transition temperature of 0 ° C. or less and (D) ethylene glycol units of 4 to 12 A hydrous soft contact lens comprising a copolymer obtained by polymerizing a copolymer component containing polyethylene glycol di (meth) acrylate.   The component (A) is 60 to 85% by weight, the component (B) is 8 to 18% by weight, the component (C) is 5 to 15% by weight, and the component (D) is 0.01 to 2.0% by weight. The hydrous soft contact lens according to claim 1. The component (C) is represented by the following formula (1)

[Wherein, n is an integer of 1 to 9, R ₁ is hydrogen or a methyl group, and R ₂ is alkyl having 1 to 20 carbon atoms]
The hydrous soft contact lens according to claim 1, which is a (meth) acrylate represented by the formula:   The hydrous soft contact lens according to claim 1, wherein the component (C) is ethoxyethyl methacrylate and the component (D) is nanoethylene glycol dimethacrylate.