JPS61292612A - High-strength soft contact lens - Google Patents

Abstract

PURPOSE:To provide a soft contact lens having all of a high moisture content of >=60%, high tensile strength and practicably substantial elongation to breakage by copolymerizing an N-vinyl pyrrolidone, hydrophobic monomer, vinyl acetate, unsatd. carboxylic acid and specific crosslinking agent at a specified ratio. CONSTITUTION:This soft contact lens consists of the copolymer consisting of 60-95wt% N-vinyl pyrrolidone, 5-40wt% at least one kind of hydrophobic monomer selected from a specific acrylate and methacrylate, 2-20wt% vinyl acetate, 0-20wt% unsatd. carboxylic acid having one ethylenic unsatd. bond and 0.02-3.0wt% at least one kind of crosslinking agent selected from the specific diolefin expressed by the formula and having >=60% moisture content. The hydrophobic monomer controls the moisture content of the copolymer and provides tensile strength to the copolymer. The vinyl acetate increases the elongation without decreasing the moisture content of the copolymer. The crosslinking agent contributes to the moisture content and tensile strength of the copolymer. The mixed liquid is poured into a prescribed forming mold and after the mold is hermetically sealed, the mold is heated. The result ant bar material is machined and polished to form the lens. The lens is subjected to satd. swelling in a physiological salt soln.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a novel soft contact lens, and more specifically, a soft contact lens that has a water content of 60% or more, has high mechanical strength, and is colorless and transparent. Pertains to soft contact lenses.

[Prior art] Conventionally, soft contact lens materials have mainly been made of O.
Homopolymers or copolymers of acrylic derivatives with H groups have been used. These materials have the property of absorbing water and swelling, have good transparency, and have excellent machinability, so they are suitable for producing soft contact lenses that are comfortable to wear.

Furthermore, in recent years, high water-containing soft contact lenses have appeared that allow contact lenses to be worn continuously for long periods of time by further increasing the water content of lens materials. This high water content soft contact lens is made of a material whose main component is N-vinylpyrrolidone and can absorb a large amount of water, so it can supply enough oxygen through the lens, which is necessary for the corneal physiology, thereby improving corneal metabolism. The function is not impaired and physiological safety for the eyes can be ensured.

[Problems to be Solved by the Invention] However, when the water content of the above-mentioned high water content soft contact lenses increases, the strength rapidly decreases, resulting in damage to the lenses, scratches on the lens surfaces, etc. There is a problem with durability. In addition, if we try to increase the mechanical strength of the material to compensate for these drawbacks, the water content of the lens will decrease, the supply of oxygen necessary for corneal physiology will be inadequate, and furthermore, the elongation to the point of breakage will be poor. Therefore, there is a drawback that it is easily damaged due to slight deformation.

[Means for Solving the Problems] As a result of intensive research to improve the drawbacks of conventional high water content soft contact lenses, the present inventors found that N-vinylpyrrolidone, hydrophobic monomers, vinyl acetate, unsaturated carbon When an acid and a specific crosslinking agent are copolymerized at a certain ratio,
We discovered that high moisture content and high strength are achieved at the same time.
The present invention has now been completed.

An object of the present invention is to provide a soft contact lens that has a high water content of 60% or more, high tensile strength, and practically sufficient elongation at break.

Another object of the present invention is to provide a high water content contact lens that has high oxygen permeability and can be worn continuously for a long period of time.

Another object of the present invention is to provide a colorless and transparent high water content contact lens.

The soft contact lens of the present invention contains 60-95111% of N-vinylpyrrolidone, 5-40% by weight of at least one hydrophobic monomer selected from Group A, and 2-vinyl acetate.
Water content of 20% by weight, unsaturated carboxyl having one ethylenically unsaturated bond @0-20% by weight, and 0.02-3.0% by weight of at least one crosslinking agent selected from Group 8. Consists of 60% or more copolymer.

(Group A) Phenyl acrylates, benzyl acrylates, phenyl methacrylates, benzyl methacrylates, phenoxyedyl acrylate, phenoxyethyl methacrylate cyclohexyl acrylate, cyclohexyl methacrylate (group 8> XX CH2=C-COO(CH2CH20) aQC-( ,
-CH2 (X is H or CH3, a is an integer from 3 to 23)
CH2=C-Coo (CH2CH2CH20),
QC-C=CH2 (X is H or CH3, b is 2-14
(integer up to )X CH3X l 1 1 CH2=C-Coo (CH2CHO) cQC-C=
CH2 (X is H or CH3, C is an integer from 3 to 14) Phenyl acrylates in group A include phenyl acrylate, O-methyl phenyl acrylate, m-methyl phenyl acrylate, p-methyl phenyl acrylate, 0-methoxyphenylacrylate,
m-methoxyphenylacrylate, p-methoxyphenylacrylate, 0-ethoxyphenylacrylate, m-ethoxyphenylacrylate, p-ethoxyphenylacrylate, biphenylacrylate, 0-benzylphenyl acrylate, m-benzylphenyl acrylate, p-benzylphenyl acrylate etc. can be mentioned.

Examples of benzyl acrylates include benzyl acrylate, 0-methylbenzyl acrylate, m-methylbenzyl acrylate, p-methylbenzyl acrylate,
0-methoxybenzyl acrylate, m-methoxybenzyl acrylate, p-methoxybenzyl acrylate,
〇-Ethoxybenzyl acrylate, m-ethoxybenzyl acrylate, p-ethoxybenzyl acrylate, on-butylbenzyl acrylate, m-n-butylbenzyl acrylate, p-n-butylbenzyl acrylate, 0-phenoxybenzyl acrylate, m-
Examples include phenoxybenzyl acrylate, p-phenoxybenzyl acrylate, o-phenylbenzyl acrylate, m-phenylbenzyl acrylate, and p-phenylbenzyl acrylate.

Examples of phenyl methacrylates include phenyl methacrylate, 0-methylphenyl methacrylate, m-methylphenyl methacrylate, p-methylphenyl methacrylate, 0-methoxyphenyl methacrylate, m-
Examples include methoxyphenyl methacrylate, p-methoxyphenyl methacrylate, phenyl methacrylate, 0-benzylphenyl methacrylate, m-benzylphenyl methacrylate, and p-benzylphenyl methacrylate.

Examples of benzyl methacrylates include benzyl methacrylate, O-methylbenzyl methacrylate, m-methylbenzyl methacrylate, p-methylbenzyl methacrylate, 0-methoxybenzyl methacrylate, m-
Methoxybenzyl methacrylate, p-methoxybenzyl methacrylate, 0-ethoxybenzyl methacrylate, m-ethoxybenzyl methacrylate, p-ethoxybenzyl methacrylate, o-n-butylbenzyl methacrylate, m-n-butylbenzyl methacrylate, p-n-butylbenzyl Examples include methacrylate, 0-phenoxybenzyl methacrylate, m-phenoxybenzyl methacrylate, p-phenoxybenzyl methacrylate, 0-phenylbenzyl methacrylate, m-7enylbenzyl methacrylate, and p-phenylbenzyl methacrylate.

The hydrophobic monomer of group A adjusts the water content of the copolymer,
Among the components that impart tensile strength to the copolymer, benzyl methacrylates are particularly effective in imparting tensile strength.

Vinyl acetate does not reduce the water content of the copolymer,
It is an essential component to increase the elongation of copolymers,
By copolymerizing these components, it is possible to obtain a soft contact lens that maintains a high water content and high tensile strength, and also has a high elongation at break, in other words, it is difficult to break. The amount of vinyl acetate used is 2-20% by weight, preferably 4% by weight.
- It is in the range of 10% by weight, and if this amount is less than 2% by weight, the elongation of the copolymer cannot be improved, and if it is used in excess of 20% by weight, the tensile strength will be significantly reduced, so it is not preferred in practice. .

The crosslinking agent of group B is a component that contributes to the water content and tensile strength of the copolymer, and since it has an appropriate chain length, it exhibits a particularly remarkable effect on imparting tensile strength. Commonly used short chain crosslinking agents such as ethylene glycol dimethacrylate and allyl methacrylate cannot significantly improve the tensile strength of high water content polymers. Further, extremely long-chain crosslinking agents such as polyethylene glycol dimethacrylate (for example, 30 moles of ethylene oxide added) not only fail to improve the strength of the highly water-containing polymer, but also reduce machinability and polishability.

The amount of crosslinking agent added varies depending on the type of crosslinking agent, but it is 0.0
Selected in the range of 2-3.0%. If the amount used is outside this range, the tensile strength of the high water content polymer cannot be improved.

Furthermore, in the present invention, the use of an unsaturated carboxylic acid having one ethylenically unsaturated bond is effective in controlling the water content of the high water content polymer.

That is, by using the unsaturated carboxylic acid in combination,
It becomes easier to obtain contact lenses with high water content. Unsaturated carboxylic acids that can be used in the present invention include:
Acrylic acid, methacrylic acid, itaconic acid, crotonic acid,
Examples include pyruvic acid, fumaric acid, and maleic acid.

The soft contact lens of the present invention includes 60-95% by weight of N-vinylpyrrolidone, 5-40% by weight of at least one hydrophobic monomer selected from the Δ group, and 0.02% by weight of a crosslinking agent selected from the group B. -3.0% by weight, vinyl acetate 2-20
Weight%, unsaturated carboxylic acid having one ethylenically unsaturated bond 0-20% by weight and polymerization initiator 0.01-0.5
After pouring the liquid mixed with % by weight into a specified mold and sealing it, it is heated in a constant temperature bath for a certain period of time, and the resulting rod is cut and polished to a certain thickness to form a lens. can be obtained by saturated swelling in physiological saline.

Note that it is also possible to adopt a method of directly forming a contact lens shape using a cast polymerization method, a method of performing spin casting while irradiating ultraviolet rays, etc.

Polymerization initiators used in the present invention include azobis-based initiators such as azobisisobutyronitrile and azobisdimethylvaleronitrile, and peroxide initiators such as benzoyl peroxide, lauroyl peroxide, and diisoprogol rubber oxydicarbonate. Agents can be mentioned.

[Effects of the Invention] The soft contact lens of the present invention obtained as described above has the following excellent properties.

(1) Since the main component is N-vinylpyrrolidone, which is a hydrophilic material, it has a high water content, and therefore can transmit enough oxygen necessary for corneal physiology.

(Because it contains vinyl diacetate as a copolymer component, even though it is a high water content contact lens, it has a tensile strength that is unimaginable for similar conventional contact lenses and a practically sufficient elongation at break.) There is.

3) The contact lens of the present invention is colorless and transparent, without the pale yellow coloring unlike conventionally commercially available polyN-vinylpyrrolidone soft contact lenses, and has a high visible light transmittance.

(4) Conventionally used poly-N-vinylpyrrolidone-based contact lenses with high water content do not have strong water retention properties, so when used in a dry atmosphere, the water in the lenses evaporates and the water content decreases. soft contact lenses of the present invention are free from such defects.

[Example] Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. Note that all parts of the constituent components are expressed in parts by weight.

Example 1 88 parts of N-vinylpyrrolidone, 12 parts of benzyl methacrylate, 0.0 parts of triethylene glycol dimethacrylate.
A mixed solution consisting of 3 parts of azobisdimethylvaleronitrile and 0.05 parts of azobisdimethylvaleronitrile was poured into a mold, the mold was sealed, and then heated. The temperature was raised from 30°C to 115°C over 24 hours in a constant temperature bath. After the polymerization was completed, the copolymer was cooled to room temperature and taken out from the mold.

The copolymer was a colorless and transparent hard material.

This was cut into a contact lens shape and polished using a normal processing technique to produce a contact lens.

Next, it was immersed in 0.9% physiological saline to make it sufficiently swollen. The swollen soft contact lens was colorless and transparent as in the dry state. The water content of this lens is 80%, and the oxygen permeability coefficient is 53xlO"cm' (ST
P) cm/cm2-sec-mmHg (30℃), tensile strength when hydrated is 258G/nun2, elongation at break is 2
It was 10%.

Examples 2 to 15 Saturated swollen contact lenses were produced in the same manner as in Example 1. The measurement results are shown in Table 1. All contact lenses obtained in each example were colorless and transparent,
It exhibited higher oxygen permeability than the comparative example, and also had high tensile strength and breaking strength never seen before for a high water content contact lens, as well as a practically sufficient breaking elongation.

Balanced practical performance as a soft contact lens was achieved for the first time by combining N-vinylpyrrolidone with a specific hydrophobic monomer having a benzene ring or cyclohexyl ring, a crosslinking agent with a specific chain length, and vinyl acetate. This is an effect unique to the present invention. (Left below) (Monomer abbreviation) NVP: N-vinylpyrrolidone BZMA: Benzyl methacrylate BPA: p-benzylphenyl acrylate PHMA:
Phenyl methacrylate PEMA: Phenoxyethyl methacrylate CHMA dichlorohexyl methacrylate MMA: Methyl methacrylate VAC: Vinyl acetate AA Niacrylic acid IA: Itaconic acid MAA: Methacrylic acid A Nitriethylene glycol dimethacrylate (c
m3) B: Tetraethylene glycol di7 acrylate (cm4) C: Polyethylene glycol dimethacrylate (cm9) D = Tripropylene glycol dimethacrylate (b=3) E: Polyisopropylene glycol diacrylate (cm9) F: Ethylene glycol dimethacrylate Methacrylate G: Allyl methacrylate (Note 1) (W+ -W2) Water content (weight%) = w1 x 100% W electric is the weight at saturated water content W2 is the weight when the lens is dehydrated and dry (Note 2) The oxygen permeability coefficient is , was measured at 30° C. using a Seikaken film oxygen permeability meter (manufactured by Rika Seiki Kogyo).

The unit is 10 m (! (STP) cm / cm2-
see −n+mHo.

(Note 3) Tensile strength was determined by performing a tensile test using a dumbbell-shaped specimen cut from a swollen lens in 0.9% physiological saline at 20°C at a constant elongation rate of 54 mm/min.
It was determined by measuring the stress at break. The unit is g/
mm2゜ (Note 4) β'-! Elongation at break (%>=, xioo%β' is the length of the test piece at break

Claims (1)

[Claims] 1 60-95% by weight of N-vinylpyrrolidone, 5-40% by weight of at least one hydrophobic monomer selected from Group A, 2-20% by weight of vinyl acetate, 1 ethylenically unsaturated bond. 0-20% by weight of an unsaturated carboxylic acid and 0.02-3.0% of at least one crosslinking agent selected from Group B
A high-strength soft contact lens with a water content of 60% or more, made of a copolymer containing % by weight. (Group A) Phenyl acrylates, benzyl acrylates, phenyl methacrylates, benzyl methacrylates, phenoxyethyl acrylate, phenoxyethyl methacrylate cyclohexyl acrylate, cyclohexyl methacrylate (Group B) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (X is H or CH_3, a is an integer from 3 to 23)▲
There are mathematical formulas, chemical formulas, tables, etc.▼ (X is H or CH_3, b is an integer from 2 to 14)▲
There are mathematical formulas, chemical formulas, tables, etc.▼ (X is H or CH_3, c is an integer from 3 to 14)