JP2000010056A - Contact lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ideal lightweight contact lens having high transparency, mechanical strength and softness and low specific gravity by using an ethylene polymer having excellent transparency as a crude material. SOLUTION: This contact lens consists of an ethylene polymer and is a non moisture content soft contact lens consisting of an ethylene-based thermoplastic elastomer. Further, the contact lens consists of the ethylene polymer having >=89% transmissivity for all rays when a transmission test for rays is performed in 0.1 mm thickness, <=0.95 g/cm3 density and <=5% water content. Any ethylene polymer can be used as far as it has transparency and usually, an ethylene single polymer or copolymer of ethylene and other monomers are used. As for the ethylene single polymer, linear polyethylene or high pressure low density polyethylene are preferably used but a polyethylene resin of another class can also be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a contact lens made of an ethylene polymer. More specifically, the present invention relates to a non-water-containing soft contact lens made of an ethylene polymer which has a low specific gravity and is excellent in transparency, workability, mechanical strength, durability, feeling of wearing, and the like.

[0002]

2. Description of the Related Art Contact lenses are classified into hard contact lenses and soft contact lenses, and are used depending on the suitability of the patient and the purpose of use. Conventionally,
Hard contact lenses include methyl methacrylate, siloxanyl alkyl methacrylate in consideration of oxygen permeability (Japanese Patent Publication No. 52-33502), or fluoromethacrylate (JP-A-61-306646) for the purpose of solving contamination. Japanese Patent Application Laid-Open Publication No. HEI 7-163) has been used. These hard contact lenses are excellent in mechanical strength and tear exchangeability, and do not contain water, so that they do not require boiling sterilization or disinfectant disinfection. However, since the material is hard, there are major problems that the feeling of wearing on the eyes is low and that the material is easily affected by external stimuli.

[0003] On the other hand, soft contact lenses have characteristics that they are more easily conformable to the eyes and are more comfortable to wear than hard contact lenses, and are known to be water-containing or non-water-containing. As a hydrous soft contact lens, a lens mainly containing 2-hydroxyethyl methacrylate is known. Also, for the purpose of improving oxygen permeability or wearing feeling, a highly water-containing soft contact lens obtained by copolymerizing a water-soluble component such as N-vinylpyrrolidone or methacrylic acid is known. However, with water-containing soft contact lenses, there is a problem of lens dirt and bacteria breeding because of the water content. Met.

[0004] From a technical demand to solve such a problem unique to hydrous soft contact lenses and to also maintain the goodness as soft contact lenses, non-hydrous soft contacts that do not require sterilization treatment. Lenses are being developed. Known non-hydrous soft contact lenses include, for example, those containing a long-chain alkyl (meth) acrylate as a main component and those using silicone rubber. But long chain alkyl (meth)
Acrylate has a low mechanical strength and requires a reaction after processing in producing a lens, and is difficult to handle. Therefore, further improvement is desired. In addition, silicon rubber has drawbacks such as extremely low mechanical strength and easy attachment of lipid of lipid components and protein stains, and was not satisfactory as a material for non-hydrous soft contact lenses. . That is, as for the non-hydrous soft contact lens, no suitable material has been found to date, and the situation has not been optimized as a product.

On the other hand, the development of chemical materials today is remarkable,
Even in the case of a polyethylene resin, a material having excellent strength, durability and transparency can be realized by selecting a composition, a polymerization method, an additive and the like (Japanese Patent Laid-Open No. 6-1924).
No. 94, JP-A-8-90731, JP-A-8-907
No. 134284, JP-A-8-245842,
JP-A-8-59907, JP-A-8-81584, JP-A-8-176363, JP-A-8-31
1260, JP-A-8-73673).

In recent years, by controlling the molecular weight, the bulkiness of the molecular chains, and the like, it has become possible to limit the crystallization of an ethylene polymer, which has conventionally tended to be opaque due to crystallization, and to increase the transparency. Has been commercialized, and desired properties can be easily obtained. Further, an ethylene-based thermoplastic elastomer (for example, a polyethylene gel material of Cosmo Instruments Co., Ltd., product name: Cosmogel) using these ethylene polymers is also commercially available, and a packing material and the like using these are also being developed. (JP-A-8-277939, JP-A-7-3
08389, JP-A-10-38137, JP-A-10-1094, JP-A-9-286043, JP-A-6-172662, JP-A-2-30
No. 9064).

[0007] However, these ethylene polymers having high transparency, excellent durability and processability have been used only for films, packaging materials, adhesives, or some medical materials. Ethylene polymers were inferior in transparency and had a fixed image that they were not suitable for materials for contact lenses. Therefore, no contact lenses using ethylene polymers have been provided so far.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a non-hydrous soft contact lens which can be melt-molded, has a low specific gravity and is light, and has excellent mechanical strength, durability and wearing feeling. .

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above problems, and as a result, by using a highly transparent ethylene polymer as a material, a non-hydrous soft contact having unprecedented characteristics has been obtained. The inventors have found that a lens can be manufactured, and have completed the present invention. That is, the present invention provides the following non-hydrous soft contact lenses and contact lenses of [1] to [4]. [1] A contact lens made of an ethylene polymer. [2] A non-hydrous soft contact lens made of an ethylene-based thermoplastic elastomer. [3] A contact lens made of an ethylene polymer having a total light transmittance of 89% or more when subjected to a light transmission test with a thickness of 0.1 mm. [4] The contact lens according to [3], wherein the contact lens has a density of 0.95 g / cm ³ or less and a water content of 5% or less.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As the ethylene polymer used in the present invention, any one may be used as long as it is an ethylene polymer having transparency. Usually, an ethylene homopolymer or ethylene and another monomer are used. Is used.
The term “transparent ethylene polymer” as used herein refers to an ethylene polymer having or becoming transparent when formed into a thin contact lens shape. , Powdered, supplied in sheet form, etc., even with regard to ethylene polymer in a thick state,
It is not a condition of having transparency. Regardless of the transparency or opacity of the raw material of the ethylene polymer, any ethylene polymer which exhibits transparency when formed into a contact lens shape can be used freely in the present invention.

As the ethylene homopolymer, linear polyethylene and high-pressure low-density polyethylene are preferably used, but other classes of polyethylene resins can be used without departing from the object of the present invention. In general, linear polyethylene can be easily manufactured in low pressure processes such as gas-phase fluidized bed reactors, has excellent physical properties such as stiffness, tensile strength and elongation, and lacks processability. On the other hand, high-pressure low-density polyethylene is highly branched and has excellent processability. On the other hand, other classes of polyethylene resins include those in which long-chain branching is introduced into linear polyethylene to facilitate processability. In the present invention, any polyethylene resin that is generally known and can be obtained or manufactured can be freely used without departing from the object of the present invention.

The copolymer of ethylene and another monomer used in the present invention includes a copolymer of ethylene and an α-olefin, for example, propylene, 1-butene, 4-methylpentene-1, 1-hexene, A copolymer with octene, norbornene, or the like is used, and an α-olefin having 3 to 18 carbon atoms is particularly preferably used. One or two or more of these α-olefins can be used. The content of the α-olefin contained in the ethylene-α-olefin copolymer varies depending on the polymerization method and the physical properties to be provided, but is about 0.5 to 60% by weight, preferably 1 to 60% by weight.
40% by weight, more preferably 5 to 20% by weight,
A different content may be selected without departing from the purpose of the present invention.

Further, as a copolymer of ethylene and another monomer, a copolymer of ethylene and an unsaturated group-containing monomer, for example, styrene, α-methylstyrene, butadiene, isoprene, chloroprene, vinyl fluoride, vinyl chloride , Vinyl acetate, vinyl propionate, methyl acrylate, ethyl acrylate, butyl acrylate, acrylic acid, glycidyl acrylate, 2-hydroxyethyl acrylate, methyl methacrylate, ethyl methacrylate,
Butyl methacrylate, methacrylic acid, glycidyl methacrylate, 2-hydroxyethyl methacrylate, itaconic acid, itaconic anhydride, maleic anhydride, ethyl vinyl ether, butyl vinyl ether, acrylonitrile,
N-vinylpyrrolidone, vinylpyridine, acrylamide, methacrylamide, trimethoxyvinylsilane, γ
-Methacrylopropyltrimethoxysilane, a copolymer with carbon monoxide is used, among which vinyl acetate monomer, trimethoxyvinylsilane monomer and styrene monomer are preferably used, or methacrylic acid ester having 4 to 8 carbon atoms Is preferably used. One or more of these comonomers can be used. The content of the comonomer component contained in the copolymer varies depending on the polymerization method and physical properties to be provided, but is preferably about 70% by weight or less, preferably 50% by weight or less, more preferably 30% by weight or less. A different content may be selected without departing from the purpose of the above.

The method for producing the ethylene polymer of the present invention is not particularly limited, and a known polymerization method such as a radical polymerization method or an ionic polymerization method can be appropriately selected and used. For example, a low-density polyethylene or an ethylene- (meth) acrylic acid copolymer can be produced by a radical polymerization method, and an ethylene-α-olefin copolymer can be produced by an ionic polymerization method. In the ethylene polymer of the present invention, among the ethylene polymers described above, those having an average molecular weight in the range of 500 to 100,000 in number average molecular weight are used, and further, from the viewpoint of mechanical strength, processability, and transparency, 20
Those having a range of 00 to 50,000 are preferably used.
Although the density can be used those usually 0.84~0.95g / cm ^3, density of the ethylene polymer exceeding 0.95 g / cm ^3, transparency, flexibility, fitting of the contact lens Not preferred from the point. Also, an ethylene polymer having a total light transmittance of less than 89% at a thickness of 0.1 mm when subjected to a light transmission test is not preferred because of insufficient transparency.

These ethylene polymers meeting the object of the present invention can be obtained by appropriately selecting known production conditions and adjusting the mixing ratio and type of the monomers used.
For example, a powdery, sheet-like, commercially available ethylene polymer processed into a film shape is also an ethylene polymer suitable for the purpose of the present invention, and if it can be processed as a contact lens, it is preferably used in the present invention. Can be used. Further, in order to obtain the contact lens of the present invention, the molecular weight of the ethylene polymer, the density, the value of transparency, depending on the type and production conditions of the copolymerized monomer, even when outside the above range,
If a contact lens can exhibit satisfactory performance in terms of transparency and the like, it can be included in the scope of the present invention as long as it is a contact lens using an ethylene polymer.

In the present invention, the ethylene polymer is
In particular, an ethylene-based thermoplastic elastomer can be preferably used. Generally, an elastomer is at least 5
After removing 0% strain, quickly return to the original shape,
Also, it refers to a polymer material in which the equilibrium modulus due to entropy elasticity increases with temperature. Elastomers are also included in the above-mentioned ethylene polymers, but those which do not correspond to elastomers are also exemplified. Therefore, in the present invention, ethylene polymers having elastomer properties are used as ethylene-based thermoplastics. Specifically defined as an elastomer.

As the ethylene thermoplastic elastomer of the present invention, among the ethylene polymers, those having a JIS A hardness of 30 degrees or less, preferably 20 degrees or less, more preferably 10 degrees or less are used (JIS A hardness is JIS K63).
01). Specific materials of the ethylene-based thermoplastic elastomer of the present invention include styrene-ethylene-butylene-styrene (SEBS) and styrene-ethylene-styrene.
Propylene styrene (SEPS) and the like. In addition, ethylene-propylene copolymers filled with high fillers and oils, and commercially available as Cosmo Keiki Co., Ltd. under the trade name "Cosmogel", ethylene-styrene copolymers containing a hardness modifier are also ethylene-based. It can be included in the present invention as a thermoplastic elastomer. "Cosmogel" is a gel-like substance that captures 98% paraffinic and 2% naphthenic oils in the interstices of the network formed by the polymer chains of ethylene and styrene. Excellent characteristics. Even when cooled to -40 ° C, elongation characteristics and impact absorption characteristics hardly deteriorate.
The long linear molecules are not crosslinked with each other, but are entangled and have an Asker C hardness in the range of 0.1 to 10 degrees (JIS A hardness 1 corresponds to Asker C hardness 7).
Further, other ethylene polymers having the same properties as “cosmogels” can be included in the ethylene-based thermoplastic elastomer of the present invention.

The ethylene polymer of the present invention may optionally contain additives such as an ultraviolet absorber, an oxidation stabilizer, a coloring matter, a surfactant and the like in order to impart a function to the contact lens, if necessary. The amount may be appropriately selected according to the purpose within a range that does not impair the purpose of the present invention. Further, other polymers such as a water-absorbing polymer, a silicone polymer, and a polymer plasticizer may be blended, and the blending amount can be appropriately selected depending on the purpose within a range that does not impair the purpose of the present invention. Further, for the purpose of adjusting the hardness and the shape stability of the lens, it may be formed by blending an organic peroxide before or during molding. As the organic peroxide to be used, generally known organic peroxides may be appropriately selected and used. For example, 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexylhexane, 1-bis (t-butylperoxy) cyclohexane, 2,2-bis (t-butylperoxy) octane, n-butyl 4,4-bis (t-butylperoxy) valerate, 2,5-dimethylhexane 2,5- Dihydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, α, α′-bis (t-butylperoxy-m
-Isopropyl) benzene, 2,5-dimethyl-2,5
-Di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-
3, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, t-butylperoxyisopropyl carbonate and the like are preferably used. Among them, although it is affected by the molding temperature, especially, the 10-hour half-life temperature is 10
Those having a temperature of 0 to 200 ° C are preferably used.

The amount of the organic peroxide to be used is preferably in the range of 0.001 to 10% by weight based on the ethylene polymer or the polymer blend. If the amount is less than 0.001% by weight, the effect of the addition is small. If it exceeds 10% by weight, gelation is apt to occur, which causes problems in workability and lens uniformity, which is not preferable.

As a method for obtaining the contact lens of the present invention from an ethylene polymer, a heat molding method is suitable. Examples of the heat molding method include an injection molding method, an extrusion molding method, and a compression molding method. In particular, when an ethylene-based thermoplastic elastomer is used as a material, a non-hydrous soft contact lens can be easily molded by a heat molding method. The molding conditions of the heat molding method vary depending on the type of the ethylene polymer used, but are approximately 100 to 250.
In a temperature range of 1 ° C., for about 1 second to 10 minutes, an ethylene polymer is sandwiched in a metal, glass, or plastic mold having a desired lens size and heat molded, whereby the lens can be directly molded into a lens shape. it can. At this time, the ethylene polymer before heat molding, so that it is easy to heat mold,
It is better to process the sheet in advance.

The contact lenses obtained by these methods may be subjected to plasma treatment, UV ozone treatment,
By a known surface treatment method such as electron beam treatment and γ-ray treatment, the surface of the lens can be freely modified as a contact lens by hydrophilizing or crosslinking the surface. still,
In the present invention, JIS A
Those having a hardness of 30 degrees or less were particularly defined as soft contact lenses, and those having a water content of 5% or less were defined as non-hydrous soft contact lenses. All these types of contact lenses, including hard contact lenses, are collectively referred to as contact lenses.

[0022]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. Example 1 A contact lens was prepared according to the following procedure, and the performance was evaluated by performing a transparency test, a tensile strength test, a density measurement, an oxygen permeability test, and a hydrophilicity measurement. First, as an ethylene copolymer, an ethylene-1-butene copolymer (1-butene: 20
% By weight, number average molecular weight of 75,000) was prepared, 50 parts by weight of dicumyl peroxide was added thereto, and a two-roll tester was used at a temperature of 150 ° C.
A sheet was formed by kneading for 10 minutes. A section of this sheet
A lens-shaped test piece having a thickness of 0.1 mm, a diameter of 15 mm, and a curve of 9 mm was heated and pressed at 160 ° C. for 5 minutes under a mold having irregularities in a lens shape to obtain a lens-shaped test piece.

The obtained lens-shaped test pieces were prepared as follows:
Was evaluated in the evaluation test. 1. Transparency test The total light transmittance of the test piece was measured at room temperature with a turbidimeter manufactured by Nippon Denshoku Co., Ltd., and the transparency was evaluated. The results are shown in Table 1 as light transmittance. 2. Tensile strength test A test piece was tested at a tensile speed of 200 mm / min according to the Contact Lens Association Lens Tensile Test Method, and the tensile strength was calculated from the load at break and the elongation. The result
The results are shown in Table 1 as tensile strength / elongation. 3. Density measurement A test was performed by the underwater replacement method, and the density of the test piece was calculated as W1 /
W2 was determined. The results are shown in Table 1. 4. Oxygen Permeability Test The oxygen permeability coefficient of the test piece was measured in a 0.9% physiological saline solution at 35 ° C. using a Kakenhi type film oxygen permeability meter manufactured by Rika Seiki Co., Ltd. The results are shown in Table 1 as DK values. 5. Hydrophilicity measurement Using a contact angle measuring device (CA-A) manufactured by Kyowa Interface Chemical Co., Ltd., the contact angle of the test piece with water was determined, and the hydrophilicity was evaluated. The results are shown in Table 1.

[0024]

[Table 1]

From the results of the above evaluation test, ethylene-1-
It was confirmed that the contact lens made of the butene copolymer had extremely good performance as a non-hydrous soft contact lens.

Example 2 As an ethylene copolymer, an ethylene-vinyl acetate copolymer (containing 39% by weight of vinyl acetate and having a number average molecular weight of 150)
00) was prepared and 50 parts by weight of 1,1-bis (t-
(Butylperoxy) 3,3,5-trimethylcyclohexylhexane (0.02 parts by weight) was added, and the mixture was kneaded at 150 ° C. for 10 minutes using a two-roll tester to form a sheet. A section of this sheet was sandwiched between a mold having a thickness of 0.1 mm, a diameter of 15 mm, and a curve having a concave and convex lens shape of 9 mm, and heated and pressed at 160 ° C. for 5 minutes.
A lens-shaped test piece was obtained. An evaluation test was performed on the obtained lens-shaped test piece in the same manner as in Example 1.
The results are shown in Table 1. From the test results, it was confirmed that the contact lens made of the ethylene-vinyl acetate copolymer had extremely good performance as a non-hydrous soft contact lens.

Example 3 An ethylene-vinylsilane copolymer (trimethoxyvinylsilane: containing 20% by weight, number average molecular weight 10,000) was prepared as an ethylene copolymer, and a two-roll tester was used at a temperature of 150 ° C. And kneaded for 10 minutes to form a sheet. A section of this sheet was prepared with a thickness of 0.1 mm and a diameter of 1 mm.
A lens-shaped test piece was obtained by sandwiching a mold having a lens shape of 5 mm and a curve of 9 mm with irregularities in the shape of irregularities by heating and pressing at 150 ° C. for 5 minutes. An evaluation test was performed on the obtained lens-shaped test piece in the same manner as in Example 1. The results are shown in Table 1. From the test results, it was confirmed that the contact lens made of the ethylene-vinylsilane copolymer had extremely good performance as a non-hydrous soft contact lens.

Example 4 A sheet of a polyethylene gel material “Cosmogel” (trade name, manufactured by Cosmo Keiki Co., Ltd.), which is an ethylene-based thermoplastic elastomer, was prepared as an ethylene copolymer. 0.1 mm, diameter 15 mm, curve 9 mm sandwiched by a mold with irregularities
Heating and pressurizing were performed at 150 ° C. for 1 minute to obtain a lens-shaped test piece. An evaluation test was performed on the obtained lens-shaped test piece in the same manner as in Example 1. The results are shown in Table 1. From the test results, it was confirmed that the contact lens made of the polyethylene gel material “Cosmogel” had extremely good performance as a non-hydrous soft contact lens.

Example 5 As an ethylene homopolymer, 50 parts by weight of a high-pressure low-density polyethylene (number average molecular weight 7,500) was prepared, 1 part by weight of dicumyl peroxide was added thereto, and a two-roll test was conducted at 150 ° C. The mixture was kneaded for 10 minutes using a machine to form a sheet. A section of this sheet is sandwiched between molds having a thickness of 0.1 mm, a diameter of 15 mm, and a curve of 9 mm with irregularities in a lens shape, and heated and pressed at 160 ° C. for 5 minutes to obtain a lens-shaped test piece. Was. An evaluation test was performed on the obtained lens-shaped test piece in the same manner as in Example 1. The results are shown in Table 1. From the test results, it was confirmed that the contact lens made of high-pressure low-density polyethylene had extremely good performance as a non-hydrous soft contact lens.

Comparative Example 1 As a non-water-containing soft contact lens material, 50 parts by weight of silicone rubber was prepared, 0.1 part by weight of benzoyl peroxide was added thereto, and a two-roll test machine was used at 150 ° C. And kneaded for 10 minutes to form a sheet. A section of this sheet is sandwiched by a molding die having a thickness of 0.1 mm, a diameter of 15 mm, and a curve of 9 mm with projections and depressions,
The sample was heated and pressed at 160 ° C. for 5 minutes to obtain a lens-shaped test piece. About the obtained lens-shaped test piece,
An evaluation test was performed in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 10 parts by weight of methyl methacrylate and 0.1 part by weight of ethylene glycol dimethacrylate were prepared as hard contact lens materials, and 0.01 part by weight of azobisisobutyronitrile was used as a radical polymerization initiator. Was added and polymerized at a temperature of 60 ° C. for 20 hours to produce a transparent cured test tube. This was cut into a lens shape having a thickness of 0.1 mm, a diameter of 15 mm, and a curve of 9 mm using a lathe to obtain a lens-shaped test piece. An evaluation test was performed on the obtained lens-shaped test piece in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 3 As a water-containing soft contact lens material, 10 parts by weight of 2-hydroxyethyl methacrylate and 0.1 part by weight of ethylene glycol dimethacrylate were prepared, and azobisisobutyro was used as a radical polymerization initiator. 0.01 part by weight of nitrile was added and polymerized at 60 ° C. for 20 hours to prepare a transparent cured test tube. This was cut into a lens shape using a lathe and then hydrated with physiological saline to obtain a lens-shaped test piece having a thickness of 0.1 mm, a diameter of 15 mm, a curve of 9 mm, and a moisture content of 28% by weight. Was. Example 1 about the obtained lens-shaped test piece
An evaluation test was performed in the same manner as described above. The results are shown in Table 1.

From the above, the polyethylene-based non-water-containing soft contact lens of the example exhibited the same performance as the contact lens of the existing material shown in the comparative example in light transmittance and tensile strength, and also exhibited elongation. In terms of rate and density,
It was found that the contact lens exhibited much better performance than the contact lens of the comparative example, and had characteristics that did not exist as a contact lens.

[0034]

The contact lens of the present invention can be formed by injection molding by using an ethylene polymer having excellent transparency.
It could be easily obtained by molding by a heat molding method such as extrusion molding and compression molding. Conventionally, there is no contact lens using an ethylene polymer, and the transparency, mechanical strength, and flexibility are high, and the specific gravity is low by using an ethylene polymer with excellent transparency as a material. The ideal contact lens was realized. Furthermore,
By using a non-water-containing soft contact lens using an ethylene polymer with excellent transparency, sterilization treatment is not required, wearability is good, and movement of the lens on the cornea is good,
For the first time, a non-water-containing polyethylene soft contact lens useful in industry was provided.

Claims (4)

[Claims] 1. A contact lens comprising an ethylene polymer. 2. A non-hydrous soft contact lens comprising an ethylene-based thermoplastic elastomer. 3. A contact lens comprising an ethylene polymer having a total light transmittance of 89% or more when subjected to a light transmittance test with a thickness of 0.1 mm. 4. The contact lens according to claim 3, which has a density of 0.95 g / cm ³ or less and a water content of 5% or less.