JPH07333566A - Soft contact lens - Google Patents

Abstract

PURPOSE:To obtain a soft contact lens which has low rubber hardness, has excellent toughness in spite of the low rubber hardness, has excellent shape stability and good transparency in spite of a hydrous state and provides an excellent wearing feel by using a specific copolymer. CONSTITUTION:This soft contact lens consists of the copolymer formed by polymerizing copolymer components contg. N, N-dimethyl (meth)acrylamide (component A), 2-hydroxybutyl (meth)acrylate (component beta), 2-hydroxyethyl (meth) acrylate (component C), alkyl (meth)acrylate having 1 to 12C alkyl groups (component D). The component A is a component which is basic skeleton for imparting hydrophilicity to the soft contact lens, the component B is a component to lower the rubber hardness while maintaining the toughness of the soft contact lens, the component C is a component to impart the toughness while maintaining the moisture content of the soft contact lens and the component D is a component to improve the toughness of the soft contact lens.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to soft contact lenses. More specifically, the rubber hardness is low, and the toughness is low even though the rubber hardness is low, the shape stability is excellent even in a water-containing state, the transparency is good, and the wear feeling is excellent. Regarding soft contact lenses.

[0002]

2. Description of the Related Art Conventionally, soft contact lenses containing 2-hydroxyethyl methacrylate as a main component and soft contact lenses containing N-vinyl-2-pyrrolidone as a main component have high rubber hardness. It is difficult to fit on, and to get a good wearing feeling,
A lens having several types of base curves suitable for various eyeball curves is required, and there is a problem that the lens stock increases and the lens price rises.

In addition, the soft contact lens obtained by using 2-hydroxyethyl methacrylate as a main component becomes easy to fit to the eyeball when the center thickness is as thin as 0.035 mm. The base curve may be one type because it gives a better wearing feeling. However, such a soft contact lens has a problem that it is too thin to be handled and is extremely difficult to handle.

Further, JP-A-61-166516, JP-A-61-226728 and JP-A-62.
Japanese Patent Laid-Open No. -1112929 discloses a high water content, high strength soft contact lens obtained by using N, N-dimethylacrylamide and alkyl methacrylate as main components. However, since such a soft contact lens has a relatively high rubber hardness, there is a problem that the lens stock increases and the lens price rises similarly to the above, and the restorability when deformed is inferior, and the soft contact lens in a water-containing state. There is a problem that the shape stability of is extremely poor.

[0005]

In view of the above-mentioned prior art, the present inventors have found that the rubber hardness is low, and the toughness is excellent despite the low rubber hardness, and the shape is stable even in a water-containing state. As a result of intensive research to obtain a soft contact lens that has excellent transparency, good transparency, is easy to handle, and has a low price and an excellent wearing feeling, specific (meth) acrylamide and hydroxyl Group-containing (meth) acrylate and alkyl (meth)
It was found that a soft contact lens having all of the above properties can be obtained when a copolymer composed of a copolymerization component containing acrylate as a main component is used, and the present invention has been completed.

[0006]

That is, the present invention is
(A) N, N-dimethyl (meth) acrylamide,
(B) 2-hydroxybutyl (meth) acrylate,
The present invention relates to a soft contact lens comprising a copolymer obtained by polymerizing a copolymerization component containing (C) 2-hydroxyethyl (meth) acrylate and (D) an alkyl (meth) acrylate having an alkyl group having 1 to 12 carbon atoms. .

[0007]

FUNCTION AND EXAMPLE As described above, the soft contact lens of the present invention is (A) N, N-dimethyl (meth).
Acrylamide, (B) 2-hydroxybutyl (meth)
Copolymerization containing acrylate, (C) 2-hydroxyethyl (meth) acrylate and (D) alkyl (meth) acrylate having an alkyl group having 1 to 12 carbon atoms (hereinafter referred to as alkyl (meth) acrylate (D)). It is obtained from a copolymer obtained by polymerizing components.

The N, N-dimethyl (meth) acrylamide (A) used in the present invention is a basic skeleton for imparting hydrophilicity to the obtained soft contact lens.

If the compounding amount of the N, N-dimethyl (meth) acrylamide (A) is too small,
Since the water content of the obtained soft contact lens tends to be insufficient, 30% by weight or more of the total amount of the copolymerization component,
Above all, it is preferable to adjust the content to 33% by weight or more, and when it is too much, on the contrary, the water content of the soft contact lens tends to be too high, resulting in insufficient mechanical strength. 4 of the total amount of copolymerization components
It is preferable to adjust the content to be 5% by weight or less, especially 40% by weight or less.

The 2-hydroxybutyl (meth) acrylate (B) used in the present invention is a component for reducing the rubber hardness while maintaining the toughness of the obtained soft contact lens. Furthermore, since such 2-hydroxybutyl (meth) acrylate (B) is a monomer having a hydroxyl group, the above characteristics can be exhibited without lowering the water content of the soft contact lens.

When the compounding amount of the 2-hydroxybutyl (meth) acrylate (B) is too small, the toughness of the soft contact lens is obtained by using the 2-hydroxybutyl (meth) acrylate (B). Since the effect of lowering the rubber hardness while maintaining the above tendency tends to be insufficiently expressed, it is preferable to adjust the content to be 5% by weight or more, especially 10% by weight or more of the total amount of the copolymerization component. In the case of a large amount, the rubber hardness of the obtained soft contact lens tends to be too low and the shape stability tends to be poor. Therefore, 35% by weight or less of the total amount of the copolymerization component, especially 30
It is preferable to adjust the content to be not more than weight%.

The 2-hydroxyethyl (meth) acrylate (C) used in the present invention is a component for imparting toughness while maintaining the water content of the obtained soft contact lens.

If the amount of the 2-hydroxyethyl (meth) acrylate (C) is too small, the resulting soft contact lens tends to have insufficient toughness. Of 10
It is preferable to adjust the content to be not less than 15% by weight, especially not less than 15% by weight, and when it is too much, the contribution to the water content is much larger than that of the 2-hydroxyethyl (meth) acrylate (C). Since the blending amount of the N, N-dimethyl (meth) acrylamide (A) becomes relatively small, it tends to be difficult to obtain a soft contact lens having a sufficient water content. It is preferable to adjust the content to be 50% by weight or less, especially 45% by weight or less.

The alkyl (meth) acrylate (D) used in the present invention is a component for improving the toughness of the obtained soft contact lens.

The alkyl (meth) acrylate (D)
The alkyl group in may be linear, branched or cyclic, and when the alkyl group has too many carbon atoms, the copolymer becomes cloudy and a soft contact lens is obtained. Therefore, the carbon number is 1 to 12, and preferably 1 to 6, since the transparency may be lowered.

The alkyl (meth) acrylate (D)
As typical examples of, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, heptyl Examples include (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, and dodecyl (meth) acrylate, which may be used alone or in admixture of two or more. Among them, methyl (meth) acrylate is particularly preferable from the viewpoints of low cost and easy handling.

The alkyl (meth) acrylate (D)
If the compounding amount of is too small, the toughness of the obtained soft contact lens tends not to be sufficiently improved. Therefore, the content should be 3% by weight or more, especially 5% by weight or more of the total amount of the copolymerization components. It is preferable to adjust, and if there is too much, the water content of the soft contact lens tends to decrease, so
It is preferable that the amount is adjusted to 20% by weight or less, especially 15% by weight or less of the total amount of the copolymerization component.

As described above, the soft contact lens of the present invention comprises N, N-dimethyl (meth) acrylamide (A), 2-hydroxybutyl (meth) acrylate (B), 2-hydroxyethyl (meth) acrylate ( It is obtained from a copolymer obtained by polymerizing a copolymerization component containing C) and an alkyl (meth) acrylate (D). In the present invention, other than these, these copolymers may be used depending on the purpose. A copolymerization component that can be copolymerized with the polymerization component can be used.

For example, when it is intended to impart appropriate hardness and viscosity to the obtained copolymer so as to improve the workability at the time of cutting to obtain a desired contact lens shape, It is preferable to use (meth) acrylic acid as a copolymerizable component that is copolymerizable with the copolymerizable component.

If the amount of the above-mentioned (meth) acrylic acid is too large, the viscosity of the copolymer obtained on the contrary decreases to become brittle and hard, and the workability at the time of cutting deteriorates. Since there is a tendency for size change to easily occur during the hydrous treatment, 5% by weight or less of the total amount of the copolymerization component,
It is preferable to adjust the amount to 3% by weight or less, and if it is too small, the effect of improving the processability due to the use of such (meth) acrylic acid tends not to be sufficiently exhibited. It is preferable that the amount is adjusted to 0.1% by weight or more, especially 1% by weight or more of the total amount of the copolymerization components.

Further, for example, in order to further improve the shape stability and mechanical strength of the obtained soft contact lens, it is preferable to add a crosslinking agent to the copolymerization component.

Typical examples of the cross-linking agent include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di ( (Meth) acrylate, butanediol di (meth) acrylate, 2-hydroxy-1-acryloxy-3-
(Meth) with polyhydric alcohols such as methacryloxypropane, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate
Examples thereof include polyhydric esters with acrylic acid, which may be used alone or in admixture of two or more, but among these, ethylene glycol di (meth) is inexpensive and easy to handle. ) Acrylate is particularly preferred.

If the amount of the cross-linking agent is too large, the water content of the obtained soft contact lens tends to decrease, so that the total amount of the copolymerization component is 1%.
It is preferable to adjust to 3 parts or less, especially 2 parts or less, relative to 00 parts (weight part, the same applies below), and if it is too small, it is possible to control the water content of the soft contact lens. Since it tends to be difficult, it is preferable to adjust the amount to be 0.01 part or more, particularly 0.1 part or more, based on 100 parts of the total amount of the copolymerization component.

Further, in the present invention, for example, a polymerizable ultraviolet absorber for imparting ultraviolet absorption to the obtained soft contact lens, a polymerizable ultraviolet absorbing dye,
A polymerizable dye or the like for coloring the soft contact lens can be used as a copolymerization component, and the blending amount of these is preferably adjusted appropriately according to the application, purpose and the like.

When obtaining the soft contact lens of the present invention, N, N-dimethyl (meth) acrylamide (A), 2-hydroxybutyl (meth) acrylate (B), 2- Hydroxyethyl (meth) acrylate (C) and alkyl (meth) acrylate (D) and, if necessary, a copolymerization component such as (meth) acrylic acid and a cross-linking agent are polymerized to obtain a copolymer, A method of subjecting the polymer to mechanical processing such as cutting and polishing is preferably used.

As a method for obtaining the above-mentioned copolymer, for example, a glass tube, a polypropylene tube, a polytetrafluoroethylene tube, or a tube made of a soft vinyl chloride resin between two glass plates is used. And
A mixture of a radical polymerization initiator and a copolymerization component is injected into a plate-shaped void formed by fixing two glass plates with a stopper, and then, for example, 25 to 5
A method of heating at about 5 ° C. for several hours to several tens of hours to polymerize, and then sequentially heating up to about 120 ° C. for 10 hours to complete the polymerization (heat polymerization method), in the tube or the plate-like void After injecting a mixture of a photopolymerization initiator and, if necessary, a sensitizer with a copolymerization component, for example, a wavelength corresponding to the absorption band of activation of the photopolymerization initiator such as ultraviolet rays, microwaves, and radiation. And a method of performing polymerization by combining a heat polymerization method and a photopolymerization method, and the like.

When the above-mentioned heat polymerization method is used, the heating may be carried out in a thermostat or a thermostatic chamber, or it may be irradiated with electromagnetic waves such as microwaves, and the heating may be carried out stepwise. .

In the production of the copolymer of the present invention, it is preferable to employ the usual bulk polymerization method in order to obtain good productivity and high efficiency. However, if necessary, the solution polymerization method may be employed. You can also

In the production of the above-mentioned copolymer, if strain occurs in the copolymer due to polymerization shrinkage or the like, heating and then gradual cooling may be carried out in order to eliminate the strain. preferable.

Representative examples of the radical polymerization initiator include, for example, azobisisobutyronitrile, azobis (2,4-dimethylvaleronitrile), benzoyl peroxide, diisopropylperoxydicarbonate, t-butylperoxy-2. -Ethyl hexanoate, t-butyl peroxypivalate, t-butyl peroxy isopropyl carbonate, lauroyl peroxide and the like can be mentioned.

Typical examples of the photopolymerization initiator include, for example, benzoin, methyl orthobenzoyl benzoate, methyl orthobenzoyl benzoate, methyl benzoyl formate, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin-. n-
Benzoin-based photopolymerization initiators such as butyl ether; 2-
Hydroxy-2-methyl-1-phenylpropane-1-
ON, p-isopropyl-α-hydroxyisobutylphenone, pt-butyltrichloroacetophenone,
2,2-dimethoxy-2-phenylacetophenone,
α, α-dichloro-4-phenoxyacetophenone,
Phenone-based photopolymerization initiators such as N, N-tetraethyl-4,4-diaminobenzophenone; 1-hydroxycyclohexyl phenyl ketone; 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime; 2 Examples include thioxanthone-based photopolymerization initiators such as chlorothioxanthone and 2-methylthioxanthone; dibenzosubalone; 2-ethylanthraquinone; benzophenone acrylate; benzophenone; benzyl.

The radical polymerization initiator or photopolymerization initiator may be used alone or in combination of two or more, and the amount of the polymerization initiator used may be 100 parts by weight of the total amount of the copolymerization components. It is preferably about 0.001 to 1 part, especially about 0.01 to 0.2 part.

Next, a soft contact lens may be molded by subjecting the obtained copolymer to mechanical processing or the like, and for such molding, a molding method that is commonly used by those skilled in the art can be adopted. . As such a molding method,
For example, polymerization of the copolymerization component is carried out in an appropriate tube or sheet-like void as described above, and after obtaining a copolymer of, for example, a rod shape, a block shape, a plate shape, mechanical processing such as cutting or polishing. And a mechanical processing method for processing into a desired contact lens shape.

Thus, the soft contact lens of the present invention can be obtained. Further, the obtained soft contact lens is swollen in pure water and boiled, and then swollen in a physiological saline solution so as to be appropriately swollen with water. It can be a soft contact lens.

The soft contact lens of the present invention has excellent toughness, even though it has a very low rubber hardness of about 5 to 20. In consideration of flexibility and shape stability in a water-containing state after lens processing, the rubber hardness of the soft contact lens is preferably 8-18.

The soft contact lens of the present invention comprises
Since it exhibits an appropriate water content of about 45 to 70% by weight, it is excellent in the feeling of wearing and is excellent in shape stability even in the state of exhibiting such water content. In consideration of oxygen permeability, mechanical strength and shape stability, the soft contact lens preferably has a water content of 48 to 65% by weight.

Next, the soft contact lens of the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1 N, N-dimethylacrylamide 38 parts, 2-hydroxybutyl methacrylate 20 parts, 2-hydroxyethyl methacrylate 30 parts, methyl methacrylate 12 parts and ethylene glycol dimethacrylate 0.2 parts, and as a polymerization initiator Azobis (2,4-dimethylvaleronitrile) (0.08 part) was thoroughly mixed, deaerated, and then poured into a polypropylene test tube, and the inside was replaced with nitrogen gas, and the container was tightly sealed.

Next, the test tube was transferred into a circulating constant temperature water tank and heated at 40 ° C. for 12 hours, and then 50 ° C. to 50 ° C.
The temperature was raised continuously to 110 ° C. over 12 hours to complete the polymerization to obtain a rod-shaped copolymer.

The obtained copolymer was subjected to a cutting process, swollen in pure water and boiled for 30 minutes. Then, the pure water was exchanged and the boiling was repeated twice more. After that, boiling was performed in physiological saline for 30 minutes to complete the predetermined amount of water absorption and elution of eluate to obtain a soft contact lens.

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

(A) Moisture content The diameter obtained by cutting the copolymer is about 12 to 14
5 pieces of circular test pieces having a thickness of 0.5 mm and a thickness of 0.5 mm were subjected to water absorption and elution treatment in the same manner as above, and were subjected to 1 at 20 ° C.
After left for 2 hours, the water on the surface of the test piece was quickly wiped off with Kimwipe (manufactured by Toki Kimberley Co., Ltd.) and the weight of each of the five test pieces (weight when wet, indicated as W (g)) was measured. did.

Next, each test piece was transferred into a drier, and the temperature was changed to 60.
After being dried at ℃ for 15 hours and allowed to cool to room temperature, each weight (weight when dried, indicated as W ₀ (g)) was measured,
The water content (% by weight) of each test piece was calculated based on the following formula. In Table 1, the average value of 5 test pieces is shown.

Moisture content (% by weight) = {(W−W ₀ ) / W} × 100 (b) Rubber hardness A diameter of about 12 to 14 obtained by cutting the copolymer.
mm test pieces and circular test pieces having a thickness of 4.0 mm were subjected to water absorption and elution treatment in the same manner as described above, and were subjected to 1 at 20 ° C.
After standing for 2 hours, the rubber hardness was measured with a constant pressure loader GS-710 (manufactured by TECLOCK) in accordance with the spring type hardness test (A type) of JIS K6301 "Vulcanized rubber physical test method".

In Table 1, the average value of three test pieces is shown.

(C) Shape stability in the water-containing state Diameter of about 10.2 m obtained by cutting the copolymer
m, a center contact thickness of 0.05 mm, soft contact lens is subjected to water absorption and elution treatment in the same manner as described above,
The water content was set. The specifications of the obtained soft contact lens in the water-containing state were that the size (diameter) was 13.5 mm, the center thickness was 0.07 mm, the power was -3.50 D, and the base curve was 9.00 mm.

When this soft contact lens in the water-containing state is placed on the index finger as if it were worn on the eye and the shape of the contact lens can be maintained completely, the shape stability in the water-containing state is maintained. It was evaluated as good (indicated by ◯ in the table), when it was bent and stuck to the finger, or when it was not possible to maintain a sufficient shape of the contact lens, it was evaluated as poor (indicated by x in the table).

(D) Visible Light Transmittance A film having a diameter of about 12 mm obtained by cutting a copolymer was subjected to water absorption and elution treatment in the same manner as described above to obtain a water-containing state having a thickness of 0.2 mm. It was a film.

With respect to this water-containing film, the visible light transmittance (%) in the wavelength range of 380 to 780 nm was measured using a self-recording spectrophotometer (UV-240, manufactured by Shimadzu Corporation). The measurement was carried out in water.

Further, the feeling of wearing and the durability during washing of the obtained soft contact lens were examined according to the following methods.

(E) Wearing sensation (C) Soft contact lens (size: 13.5 mm, center thickness: 0.07 mm, power: -3.50 D, produced by the shape stability test in a water-containing state) The base curve: 9.0) was worn by five randomly selected male volunteers for about 1 hour, and there was no foreign body sensation at all, and such soft contact lenses exhibited excellent wearing sensation. I found out.

(F) Durability during cleaning (e) The same soft contact lenses as those used in the above-mentioned test for wearing comfort and commercially available disposable soft contact lenses (trade name: ACCUVIEW, manufactured by Johnson & Johnson, Inc., water-containing) Rate: 58% by weight, size: 14.0
mm, center thickness: 0.07 mm, power: -3.00
D, base curve: 8.8) and a cleaning test using a puff for cleaning soft contact lenses (30 per time)
Each of them was washed for 2 seconds).

As a result, the commercially available soft contact lens was damaged during the second cleaning test, but the soft contact lens of the present invention was not damaged at all even after the cleaning test was repeated 5 times. It was found that the soft contact lens of No. 1 has a mechanical strength sufficient for practical use.

Examples 2 to 13 and Comparative Examples 1 to 7 Soft contact lenses were prepared in the same manner as in Example 1 except that the composition was changed as shown in Table 1 and Table 2.

As a polymerization initiator, azobis (2,2
The compounding amount of 4-dimethylvaleronitrile) is 0.08 parts in each case.

Further, in Examples 11 and 12,
Instead of heating the test tube at 40 ° C. for 12 hours in the circulating constant temperature water bath, it was heated at 35 ° C. for 12 hours.

The physical properties of (a) to (d) of the obtained soft contact lens were examined in the same manner as in Example 1.
The results are shown in Tables 1 and 2.

The abbreviations in Tables 1 and 2 are as shown below.

DMAA: N, N-dimethylacrylamide HBMA: 2-hydroxybutyl methacrylate HEMA: 2-hydroxyethyl methacrylate MMA: methyl methacrylate CyHMA: cyclohexyl methacrylate MAc: methacrylic acid EDMA: ethylene glycol dimethacrylate PEGDMA: polyethylene glycol dimethacrylate The (x) in the rubber hardness column of Comparative Examples 1 to 3 in Table 2 indicates that the test piece was torn during the measurement of the rubber hardness because the toughness was small.

[0060]

[Table 1]

[0061]

[Table 2]

From the results shown in Table 1, Examples 1 to 13
The resulting soft contact lens has a rubber hardness of 9-
It has a very low value of 18, and despite being soft, it does not tear during the measurement of rubber hardness, has excellent toughness, has an appropriate moisture content, and has excellent shape stability in the moisture state. Further, it can be seen that the visible light transmittance is high and the transparency is excellent at the same time.

On the other hand, the soft contact lenses obtained in Comparative Examples 1 to 3 had a low rubber hardness and were soft, but such soft contact lenses did not contain 2-hydroxybutylmethacrylate and thus were extremely It was brittle and had an agar-like appearance and was not actually usable. Further, the soft contact lenses obtained in Comparative Examples 4 and 5 include 2-hydroxybutyl methacrylate and 2
-Since a large amount of alkyl (meth) acrylate (D) is blended instead of hydroxyethyl methacrylate, the rubber hardness is 23 and 34, which is very high,
It was not possible to fabricate with various types of base curves, and these had poor shape stability in the water-containing state and had a small restoring force when deformed. Further, the soft contact lenses obtained in Comparative Examples 6 and 7 do not contain 2-hydroxyethyl methacrylate, and half of the total amount of the copolymerization components is used so that the soft contact lenses have a desired water content. Since N, N-dimethylacrylamide was used, the shape stability in the water-containing state was extremely poor, and it was not practically usable.
Incidentally, this is not clear, but it is considered that this is because the amount of N, N-dimethylacrylamide compounded was large and the molecular weight of the obtained copolymer was low.

[0064]

EFFECT OF THE INVENTION The soft contact lens of the present invention has a low rubber hardness and is excellent in toughness in spite of the low rubber hardness. For example, it has sufficient mechanical strength so that it is not easily damaged during washing. In addition to being excellent in shape stability even in a water-containing state, it has good transparency, is easy to handle, and has an excellent wearing feeling at a low price.

Claims (6)

[Claims] 1. (A) N, N-dimethyl (meth) acrylamide, (B) 2-hydroxybutyl (meth) acrylate, (C) 2-hydroxyethyl (meth) acrylate and (D) having 1 to 12 carbon atoms. A soft contact lens comprising a copolymer obtained by polymerizing a copolymerization component containing an alkyl (meth) acrylate having an alkyl group. 2. A copolymerization component comprising (A) N, N-dimethyl (meth) acrylamide 30 to 45% by weight, and (B) 2−
Hydroxybutyl (meth) acrylate 5 to 35% by weight, (C) 2-hydroxyethyl (meth) acrylate 10 to 50% by weight and (D) an alkyl (meth) acrylate 3 to 20 having an alkyl group having 1 to 12 carbon atoms. The soft contact lens according to claim 1, wherein the soft contact lens contains 100% by weight. 3. The soft contact lens according to claim 1, wherein the copolymerization component contains a crosslinking agent. 4. The amount of the cross-linking agent is 100 based on the total amount of the copolymerization components.
The soft contact lens according to claim 3, which is 0.01 to 3 parts by weight with respect to parts by weight. 5. The rubber hardness of 5 to 20,
The soft contact lens according to 2, 3, or 4. 6. The soft contact lens according to claim 1, which has a water content of 45 to 70% by weight.