JP2716712B2 - Non-hydrated soft lens and method of manufacturing the same - Google Patents

Description

The present invention relates to a non-hydrated soft lens such as a soft contact lens or an intraocular lens and a method for producing the same, and more particularly, to a substantially non-hydrated soft lens having excellent mechanical strength. The present invention relates to a non-hydrous soft lens and a method for producing the same.

[Conventional technology]

Conventionally, as a soft lens, a water-containing soft contact lens using a water-containing polymer such as poly- (2-hydroxyethyl methacrylate) as a material and poly (meth)
A non-hydrated soft contact lens made of an acrylate ester is known (Japanese Patent Publication No. 59-33887).

[Problems to be solved by the invention]

However, in general, a water-containing soft contact lens must be frequently sterilized by boiling in order to prevent the propagation of bacteria and the like, and is not easy to handle. On the other hand, a non-water-containing soft contact lens made of a poly (meth) acrylate ester has a saturated water absorption of about 3% and does not have such a disadvantage, but has a disadvantage of low mechanical strength.

An object of the present invention is to solve the above-mentioned problems, to be substantially non-water-containing, not requiring boiling disinfection, having excellent mechanical strength, and having good transparency and shape stability as a lens. And a method of manufacturing the same.

[Means for solving the problem]

That is, the non-hydrated soft lens of the present invention comprises: (A) 5 to 20 mol% of an unsaturated carboxylic acid component, and (B) 15 to 90 mol% of an alkyl acrylate component having 4 to 10 carbon atoms in an alkyl group. (C) 3 to 75 mol% of an alkyl methacrylate component having 4 to 10 carbon atoms in the alkyl group, and (D) an alkyl acrylate component having a linear alkyl group of 1 to 3 carbon atoms. It is characterized by comprising a copolymer comprising 20 mol% and (E) 0.1 to 10 mol% of a crosslinking monomer component.

 Hereinafter, the present invention will be described in detail.

The first component in the copolymer constituting the non-hydrated soft lens of the present invention (hereinafter, simply referred to as “soft lens”) is an unsaturated carboxylic acid component (hereinafter, referred to as “component (A)”).
Which is 5 to 20 mol%, preferably 5 to 15 mol%
It is contained in the ratio of. The component (A) is an essential component for improving the mechanical strength of the soft lens, and exhibits a remarkable effect in a small amount, but when the proportion is less than 5 mol%, the mechanical strength required for the soft lens is obtained. When the content exceeds 20 mol%, the hardness is increased and the flexibility as a soft lens is lost, and it becomes water-absorbing and practically non-water-containing, which is not preferable. Also,
The saturated water absorption of the soft lens of the present invention needs to be at least 5% or less.

Specific examples of the monomer that provides the component (A) include:
Examples thereof include unsaturated mono- or dicarboxylic acids such as acrylic acid, methacrylic acid, and itaconic acid, and these may be used alone or in combination of two or more.

Second example of the copolymer constituting the soft lens of the present invention
Is an acrylic acid alkyl ester component having an alkyl group having 4 to 10 carbon atoms (hereinafter referred to as “component (B)”), which is contained in a proportion of 15 to 90 mol%, preferably 25 to 80 mol%. The component (B) is a main component of the soft lens of the present invention together with the alkyl methacrylate of the component (C) described below.
If it is less than 15 mol%, the flexibility of the resulting soft lens tends to be impaired, and if it is 90 mol% or more, the mechanical strength of the soft lens will be reduced.

Specific examples of the monomer that provides the component (B) include:
n-butyl acrylate, sec-butyl acrylate,
t-butyl acrylate, n-pentyl acrylate,
n-hexyl acrylate, n-heptyl acrylate, t-amyl acrylate, 2-ethylhexyl acrylate, n-nonyl acrylate, n-octyl acrylate, n-decyl acrylate, cyclohexyl acrylate, phenoxy acrylate, benzyl acrylate, tetrahydrofurfuryl acrylate, etc. Can be mentioned. In particular, n-butyl acrylate, se
c-butyl acrylate, n-pentyl acrylate,
It is preferable to use n-hexyl acrylate, n-heptyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, and the like. These can be used alone or in combination of two or more.

Third of the copolymer constituting the soft lens of the present invention
Is a methacrylic acid alkyl ester component having an alkyl group having 4 to 10 carbon atoms (hereinafter referred to as “component (C)”). This component (C) is 3 to 75 mol%, preferably 10 to 70 mol%. It is contained in a ratio of mol%. This component (C) is also an essential component for improving the mechanical strength of the soft lens, but if its proportion is less than 3 mol%, the mechanical degree becomes insufficient, and if it exceeds 75 mol%, the elasticity of the soft lens becomes Becomes insufficient.

Specific examples of the monomer that provides the component (C) include:
n-butyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, n-heptyl methacrylate, t-amyl methacrylate, 2-ethylhexyl methacrylate, n-nonyl methacrylate,
Examples thereof include n-octyl methacrylate, n-decyl methacrylate, cyclohexyl methacrylate, phenoxy methacrylate, benzyl methacrylate, and tetrahydrofurfuryl methacrylate. In particular, it is preferable to use n-butyl methacrylate, sec-butyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, n-heptyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, or the like. These can be used alone or in combination of two or more.

No. 4 in the copolymer constituting the soft lens of the present invention
Is an acrylic acid alkyl ester component in which the alkyl group is a straight-chain alkyl group having 1 to 3 carbon atoms (hereinafter referred to as "component (D)"). This component (D) is 0 to 20 mol%, preferably 0 to 20 mol%. If the proportion of component (D) exceeds 20 mol%, the resulting soft lens will have insufficient elasticity.

Specific examples of the monomer that provides the component (D) include:
Examples thereof include methyl acrylate, ethyl acrylate, and n-propyl acrylate. These can be used alone or in combination of two or more.

Fifth of the copolymer constituting the soft lens of the present invention
Is a crosslinkable monomer component (hereinafter referred to as "component (E)"), and this component (E) is contained at a ratio of 0.1 to 10 mol%, preferably 1 to 5 mol%. When the proportion of the component (E) is less than 0.1 mol%, the shape stability of the obtained soft lens becomes poor, and when it exceeds 10 mol%, the soft lens becomes brittle.

Specific examples of the monomer that provides the component (E) include:
Divinyl compounds such as divinylbenzene, divinyltoluene, 1,4-pentadiene, 1,5-hexadiene, 1,3
-Di- or tri (meth) of polyols such as propanediol, 1,2-propanediol, 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol and trimethylolpropane Acrylic acid esters, 2- (2-hydroxy-1,1-dimethylethyl) -5-hydroxymethyl-5-ethyl-1,3-dioxane (meth) acrylate, tricyclodecanedimethylol di (meth) acrylate, Ε-caprolactone adduct of tricyclodecane dimethylol di (meth) acrylate, a reaction product of (meth) acrylic acid, trimethylolpropane and phthalic anhydride, and a reaction product of (meth) acrylic acid, propylene oxide and phthalic anhydride Reaction products,
(Meth) acrylic acid and 1,4-butanediol or 1,6-
A reaction product of hexanediol, a reaction product of (meth) acrylic acid with a glycol such as propylene glycol, ethylene glycol, diethylene glycol, and triethylene glycol and phthalic anhydride can be exemplified. In particular, dimethacrylic acid esters such as ethylene glycol, diethylene glycol, 1,4-butanediol, and 1,6-hexanediol are preferred. These can be used alone or in combination of two or more.

The soft lens of the present invention may be copolymerized with a monomer copolymerizable with the above monomer, for example, styrene, N-vinylpyrrolidone, or the like.

The soft lens of the present invention includes, for example, (1) a method of directly polymerizing a monomer mixture corresponding to the above components (A) to (E) in a mold for a soft lens, and (2) a component (a) described below. A) a monomer mixture comprising the components (d) to (d) is polymerized in a mold for a soft lens to obtain a lenticular hard copolymer, and the lenticular hard copolymer is brought into contact with a specific alcohol. (3) A monomer mixture comprising the components (a) to (d) described below is polymerized to obtain a hard copolymer, and the hard copolymer is processed to obtain a lens-shaped hard copolymer. The soft lens-shaped hard copolymer can be produced by contacting it with a specific alcohol to treat it.

In the above method (1) or (2), various types and a large number of precise molds are required according to the shape of the target soft lens, which is not economically or workable. Generally, it is preferable to use the method (3).

In the method (3), first, component (a) 15 to 90 mol%, preferably 25 to 80 mol% of unsaturated carboxylic acid component (b) alkyl acrylate having 1 to 10 carbon atoms in the alkyl group 0 to 40 mol% of ester, preferably 0 to 20
Mol% Component (c) 3-75 mol%, preferably 10-75 mol%, alkyl methacrylate having 4 to 10 carbon atoms in the alkyl group.
70 mol% Component (d) A lens-shaped lens substrate composed of a hard copolymer obtained by polymerizing a monomer mixture having 0.1 to 10 mol%, preferably 1 to 5 mol% of a crosslinkable monomer is formed. The lens substrate is subjected to an esterification treatment and, if necessary, a transesterification treatment by bringing the lens substrate into contact with a linear alcohol having 4 to 10 carbon atoms, thereby obtaining a copolymer comprising the desired components (A) to (E). Manufacture soft lenses by merging.

Here, as a specific example of the component (a), the unsaturated carboxylic acid exemplified as the monomer giving the component (A) is used, and as a specific example of the component (b), the component (B) is used.
And alkyl acrylates having 1 to 10 carbon atoms in the alkyl group exemplified as the monomer giving (D), and as specific examples of the component (c), exemplified as the monomer giving the component (C) As a specific example of the component (d), a crosslinkable monomer exemplified as a monomer for giving the component (E) can be cited as an alkyl methacrylate having an alkyl group having 4 to 10 carbon atoms.

In carrying out the method (3), the types of the components (a) to (d) are selected and polymerized at a ratio within the above range, and a hard copolymer having a glass transition temperature of about 50 ° C. or more is used. By obtaining an union and subjecting it to an esterification treatment with an alcohol and if necessary a transesterification treatment,
It is converted into a copolymer having a glass transition temperature of 20 ° C. or lower, preferably 0 ° C. or lower.

The polymerization of the monomer mixture can be performed by ordinary radical polymerization. As a method of this polymerization, a method in which the temperature is increased stepwise in the presence of a thermal polymerization initiator such as benzoyl peroxide, azobisisobutyronitrile, or the like, or a method in which benzoin, benzophenone, benzoin methyl ether, Michler's ketone, etc. A method of irradiating ultraviolet rays in the presence of a photopolymerization initiator to perform polymerization can be exemplified. The ratio of the heat polymerization initiator or the photopolymerization initiator is usually 0.01 to 1 part by weight per 100 parts by weight of the total monomers.

By cutting and polishing the hard copolymer thus obtained, a hard lens base having the same shape as the target soft lens is manufactured.

A lens substrate made of this hard copolymer was prepared by using
It is softened by contacting it with a linear alcohol of No. 10 and subjecting it to an esterification treatment and, if necessary, a transesterification treatment to obtain a desired soft lens.

The esterification treatment and, if necessary, the transesterification treatment of the lens substrate are performed by bringing the lens substrate into contact with the alcohol, but before contacting the lens substrate with the alcohol, hexane, heptane, benzene, toluene, xylene, etc. It is preferable to perform a step of immersing in an organic solvent for pre-swelling and / or a reaction of immersing in a mixed solution of the alcohol and the organic solvent.

Specific examples of the linear alcohol having 4 to 10 carbon atoms used herein include n-butyl alcohol, n-pentyl alcohol, n-hexyl alcohol, n-heptyl alcohol, n-octyl alcohol, n-nonyl alcohol, Examples thereof include n-decyl alcohol. These can be used alone or in combination of two or more.

In the esterification treatment and the transesterification treatment to be carried out as required, a reaction time of usually 1 to 100 hours at a temperature of 20 to 200 ° C is sufficient. In this reaction, it is preferable to use an acid catalyst, and the acid catalyst may be a usual esterification catalyst, that is, concentrated sulfuric acid, methanesulfonic acid, or the like.
A range of 0.2 to 10% by weight is desirable.

Here, the monomer unit derived from the unsaturated carboxylic acid in the component (a) is esterified by an alkyl group of a linear alcohol having 4 to 10 carbon atoms, and the esterification rate is less than 95%. In order to improve the mechanical strength, it is desirable to keep the esterification rate low and adjust the esterification conditions so as to be 50 to 85%.

When the esterification ratio of the unsaturated carboxylic acid is 95% or more, the mechanical strength of the obtained soft lens decreases.

Further, the linear alkyl group having 1 to 10 carbon atoms derived from the acrylate ester of the component (b) is transesterified with the alkyl group of the linear alcohol having 4 to 10 carbon atoms, and the transesterification rate is obtained. Is usually 50-95%.

In order to accelerate the reaction of the ester treatment and, if necessary, the transesterification treatment, it is preferable to remove water or lower alcohol generated by the reaction during the reaction.

By the above reaction, the lens substrate is softened to become a soft lens. In the soft lens, the catalyst used for the reaction, the linear alcohol having 4 to 10 carbon atoms, and the 1 to 3 carbon atoms are used.
It is necessary to remove these alcohols, water and the like, and it is preferable to wash them using a Soxhlet extraction device or the like. As a solvent used for this washing, it is preferable to use an organic solvent having a boiling point of 150 ° C. or lower, for example, a halogenated hydrocarbon such as dichloromethane and chloroform, a ketone such as acetone and methyl ethyl ketone, and an alcohol such as methyl alcohol and ethyl alcohol. In the case of washing using a Soxhlet extraction device, washing may be performed by refluxing at the boiling temperature of the washing solvent for 1 to 100 hours, preferably 2 to 48 hours.

The soft lens after washing is dried in a vacuum dryer at 20 to 150 ° C, preferably 40 to 120 ° C for 1 to 27 hours. The soft lens thus obtained may be further subjected to an extraction operation with water.

〔Example〕

Hereinafter, examples of the present invention will be described, but the present invention is not limited thereto.

Example 1 52 mol% of acrylic acid, 10 mol% of methacrylic acid, 15 mol% of n-butyl acrylate, n-butyl methacrylate
20 mol% and 3 mol% of ethylene glycol dimethacrylate as a crosslinkable monomer were mixed, and benzoin methyl ether was added as a photopolymerization initiator in an amount of 0.1 part by weight based on 100 parts by weight of the monomer.
The polymer was filled in a polymerization mold for contact lenses having a thickness of 1 mm, and irradiated with ultraviolet rays for 12 hours at room temperature under a nitrogen atmosphere to carry out polymerization.

After the polymerization, the obtained hard copolymer was cut and polished to obtain a contact lens-shaped lens substrate, and the lens substrate was heated in toluene and pre-swelled. This lens substrate was immersed in n-butyl alcohol containing 1% by weight of methanesulfonic acid and reacted at a reflux temperature for 30 hours to esterify acrylic acid and methacrylic acid in the copolymer.

After the reaction, use a Soxhlet extraction device with acetone for 24 hours.
The mixture was extracted at 100 ° C. for 24 hours in a vacuum dryer to obtain a non-hydrated soft contact lens.

The degree of esterification of acrylic acid and methacrylic acid with n-butyl alcohol in the above reaction was determined from the polymerization change of the lens substrate before and after the esterification treatment, and was about 85% and about 73%, respectively.

Therefore, the copolymer composition after the esterification treatment was 8.9 mol% of acrylic acid, 2.7 mol% of methacrylic acid, 58.1 mol% of n-butyl acrylate, and 27.3 mol% of n-butyl methacrylate.
Mol% and 3 mol% ethylene glycol dimethacrylate.

In the same way as this non-hydrated soft contact lens,
A disk-shaped soft slice having a thickness of 0.4 mm was separately prepared as a performance measurement sample, and the bending strength and the visible light transmittance were measured using this.

The bending strength was measured by bending the slice, sandwiching it between two glass plates, placing weights each weighing 1 kg one after another, and examining the weight placed when the breakage occurred. The visible light transmittance was measured with a double beam spectrophotometer (“200-20” manufactured by Hitachi, Ltd.). The results are shown in Table 1.

Comparative Example 1 62 mol% of acrylic acid, 15 mol% of n-butyl acrylate, 20 mol% of n-butyl methacrylate and 3 mol% of ethylene glycol dimethacrylate were mixed, and benzoyl methyl ether was added to 100 parts by weight of the monomer.
0.1 part by weight was added, polymerized and cut in the same manner as in Example 1,
Polishing was performed to obtain a lens substrate. This lens substrate was pre-swelled in toluene in the same manner as in Example 1, immersed in n-butyl alcohol, added with 4% by weight of methanesulfonic acid, and reacted at a reflux temperature for 48 hours to obtain an acrylic resin in the copolymer. The acid was esterified. After completion of the reaction, washing and drying were performed in the same manner as in Example 1 to obtain a non-hydrated soft contact lens and a disc-shaped soft slice.

The esterification ratio of acrylic acid with n-butyl alcohol in the above reaction was determined in the same manner as in Example 1 and found to be about 98%. Therefore, the copolymer composition after the esterification treatment was 1.2 mol% of acrylic acid, 75.8 mol% of n-butyl acrylate, 20 mol% of n-butyl methacrylate, and 3 mol% of ethylene glycol dimethacrylate.

The bending strength and visible light transmittance were measured in the same manner as in Example 1 using the disk-shaped soft slice. The results are shown in Table 1.

Example 2 62 mol% of acrylic acid, 10 mol% of methacrylic acid, 25 mol% of n-hexyl methacrylate and 3 mol% of ethylene glycol dimethacrylate were mixed, and 0.1 part by weight of benzoyl methyl ether was added to 100 parts by weight of the monomer. Then, polymerization, cutting and polishing were performed in the same manner as in Example 1 to obtain a lens substrate. This lens substrate was pre-swelled in toluene in the same manner as in Example 1, immersed in n-hexyl alcohol, and added with 2% by weight of methanesulfonic acid.
The reaction was carried out for a period of time to esterify acrylic acid and methacrylic acid in the copolymer. After completion of the reaction, washing and drying were performed in the same manner as in Example 1 to obtain a non-hydrated soft contact lens and a disc-shaped soft slice.

Example 1 shows the esterification ratio of acrylic acid and methacrylic acid with n-hexyl alcohol in the above reaction.
Approximately 90% and 76
%Met. Therefore, the copolymer composition after the esterification treatment is as follows: acrylic acid 6.2 mol%, methacrylic acid 2.4 mol%, n
-Hexyl acrylate 55.8 mol%, n-hexyl methacrylate 32.6 mol, and ethylene glycol dimethacrylate 3 mol%.

The bending strength and visible light transmittance were measured in the same manner as in Example 1 using the disk-shaped soft slice. The results are shown in Table 1.

Comparative Example 2 72 mol% of acrylic acid, n-hexyl methacrylate 25
Mol% and 3 mol% of ethylene glycol dimethacrylate, and 0.1 part by weight of benzoin methyl ether was added to 100 parts by weight of the monomer, and polymerized, cut and polished in the same manner as in Example 1 to obtain a lens substrate. Obtained. This lens substrate was pre-swelled in toluene as in Example 1,
The copolymer was immersed in n-hexyl alcohol, and 4% by weight of methanesulfonic acid was added. The mixture was reacted at a reflux temperature for 48 hours to esterify acrylic acid in the copolymer. After completion of the reaction, washing and drying were performed in the same manner as in Example 1 to obtain a non-hydrated soft contact lens and a disc-shaped soft slice.

The esterification ratio of acrylic acid with n-hexyl alcohol in the above reaction was determined in the same manner as in Example 1 and found to be about 98%. Therefore, the copolymer composition after the esterification treatment is 1.4 mol% of acrylic acid, 70.6 mol% of n-hexyl acrylate, and n-hexyl methacrylate.
25 mol% and ethylene glycol dimethacrylate 3
Mole%.

The bending strength and visible light transmittance were measured in the same manner as in Example 1 using the disk-shaped soft slice. The results are shown in Table 1.

Example 3 27 mono% of acrylic acid, 20 mol% of methacrylic acid, 25 mol% of methyl acrylate, 25 mol% of n-butyl methacrylate and 3 mol% of ethylene glycol dimethacrylate were mixed with benzoin methyl ether as the monomer.
0.1 part by weight was added to 100 parts by weight, polymerized in the same manner as in Example 1, cut and polished to obtain a lens substrate. This lens substrate was pre-swelled in toluene as in Example 1, and n
-Butyl alcohol was immersed, and 0.5% by weight of methanesulfonic acid was added. The mixture was reacted at a reflux temperature for 40 hours to esterify acrylic acid and methacrylic acid in the copolymer and transesterify methyl acrylate. After completion of the reaction, washing and drying were performed in the same manner as in Example 1 to obtain a non-hydrated soft contact lens and a disc-shaped soft slice.

When the esterification ratio of acrylic acid and methacrylic acid with n-butyl alcohol and the transesterification ratio of methyl acrylate with n-butyl alcohol in the above reaction were determined in the same manner as in Example 1, the esterification ratio was about 78%. And 66%, transesterification rate is 60%
Met. Therefore, the copolymer composition after the esterification and transesterification treatments contained 5.9 mol% of acrylic acid, 6.8 mol% of methacrylic acid, 10 mol% of methyl acrylate,
36.1 mol% of butyl acrylate, 38.2 mol% of n-butyl methacrylate and 3 mol% of ethylene glycol dimethacrylate.

The bending strength and visible light transmittance were measured in the same manner as in Example 1 using the disk-shaped soft slice. The results are shown in Table 1.

Example 4 20 mol% of acrylic acid, 40 mol% of methacrylic acid, 5 mol% of butyl acrylate, 32 mol% of hexyl methacrylate and 3 mol% of ethylene glycol dimethacrylate
And benzoin methyl ether was added to the monomer 10
0.1 part by weight was added to 0 part by weight, polymerized in the same manner as in Example 1, cut and polished to obtain a lens substrate. This lens base was pre-swelled in toluene as in Example 1, and n-
The copolymer was immersed in butyl alcohol, 2% by weight of methanesulfonic acid was added, and the mixture was reacted at a reflux temperature for 24 hours to esterify acrylic acid and methacrylic acid in the copolymer. After completion of the reaction, washing and drying were performed in the same manner as in Example 1 to obtain a non-hydrated soft contact lens and a disc-shaped soft slice.

When the esterification ratio of acrylic acid and methacrylic acid in the above reaction with n-butyl alcohol was determined in the same manner as in Example 1, the esterification ratio was about 85% each.
% And 75%. Accordingly, the copolymer composition after the esterification treatment is 3 mol% of acrylic acid, 10 mol% of methacrylic acid, 22 mol% of n-butyl acrylate, 30 mol% of n-butyl methacrylate, 32 mol% of hexyl methacrylate, and Methacrylate 3 mol%
Met.

The bending strength and visible light transmittance were measured in the same manner as in Example 1 using the disk-shaped soft slice. The results are shown in Table 1.

[Effect of the Invention] As described above, since the soft lens of the present invention is made of a copolymer having a specific component composition, it is substantially non-water-containing, does not require boiling disinfection, and has high mechanical strength. It has excellent transparency and shape stability as contact lenses and intraocular lenses. Further, according to the present invention, an excellent soft lens can be manufactured very easily.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Takao Shimizu 2-32-13 Shimododa, Toda City, Saitama Prefecture (56) References JP-A-48-75047 (JP, A) JP-A-53-121643 (JP) , A) JP-A-62-127825 (JP, A)

Claims (2)

(57) [Claims] (A) 5 to 20 mol% of an unsaturated carboxylic acid component; (B) 15 to 90 mol% of an alkyl acrylate component having 4 to 10 carbon atoms in an alkyl group; (D) an alkyl acrylate component having a linear alkyl group having 1 to 3 carbon atoms, 0 to 20 mol%, and (D) an alkyl methacrylate component having 4 to 10 carbon atoms, and 3 to 75 mol%. E) A non-water-containing soft lens comprising a copolymer comprising 0.1 to 10 mol% of a crosslinkable monomer component. 2. (a) 15 to 90 mol% of an unsaturated carboxylic acid, (b) 0 to 40 mol% of an alkyl acrylate having 1 to 10 carbon atoms of an alkyl group, (c) carbon number of an alkyl group Is a hard copolymer obtained by polymerizing a monomer mixture having 3 to 75 mol% of a methacrylic acid alkyl ester having a molecular weight of 4 to 10 and (d) 0.1 to 10 mol% of a crosslinkable monomer. Then, this lens substrate is subjected to an esterification treatment or an esterification treatment and a transesterification treatment by contacting with a linear alcohol having 4 to 10 carbon atoms, so that the esterification rate of the unsaturated carboxylic acid is reduced.
The method for producing a lens according to claim 1, wherein the esterification reaction is stopped at less than 95%.