Silicone hydrogel, contact lens, method for producing silicone hydrogel, and method for producing contact lens

Abstract

Provided are: a silicone hydrogel having excellent surface hydrophilicity that is stable over a long period without requiring a surface treatment, e.g., a plasma treatment, even when a hydrophobic mold, e.g., a polypropylene mold, is used; and a method for producing the silicone hydrogel. A silicone hydrogel according to one aspect of the present invention contains water. In a dried object formed by removing the water from the silicone hydrogel, the ratio of the average value (A') of O / Si concentration ratios at a first measurement point to a third measurement point to the average value (B') of O / Si concentration ratios at a fourteenth measurement point to a sixteenth measurement point, A' / B', is 1.20 or higher, the measurement points being defined separately.

Description

Silicone hydrogel, contact lens, method for manufacturing silicone hydrogel, and method for manufacturing contact lens

[0001] The present invention relates to a silicone hydrogel, a contact lens, a method for producing the silicone hydrogel, and a method for producing a contact lens. This application claims priority to Japanese Patent Application No. 2023-110075 filed on July 4, 2023, and Japanese Patent Application No. 2024-050042 filed on March 26, 2024, the contents of which are incorporated herein by reference.

[0002] Silicone hydrogels, due to their high oxygen permeability, are used as materials for contact lenses, intraocular lenses, and other devices. Soft contact lenses are typically manufactured using the cast molding method. Polypropylene molds are often used in this method. However, due to the hydrophobic nature of polypropylene, silicone monomers tend to polymerize in an oriented state on the mold surface, resulting in a low hydrophilicity of the lens surface. Insufficient hydrophilicity of the lens surface can lead to adhesion of lipids and proteins, which can cause lens opacity and eye diseases. Furthermore, the tendency for tear film breakdown can lead to discomfort such as dry eyes and friction, as well as conditions such as blepharitis.

[0003] As a technique for improving the surface hydrophilicity of such contact lenses using silicone hydrogel, Patent Document 1 proposes a method in which a hydrophilic monomer is vaporized, followed by generation of plasma to form a hydrophilic polymer film on the lens surface. Also, Patent Document 2 proposes a method in which a molded contact lens is immersed in a storage solution containing a surfactant and a hydrophilic polymer, and the surfactant is attached to the contact lens surface.

[0004] Furthermore, Patent Document 3 proposes a method of improving hydrophilicity by adding and curing a polymerizable amphiphilic substance to expose hydrophilic groups on the surface. Patent Document 4 proposes a method of forming a stable hydrophilic surface on a contact lens by using a monomer with a specific structure that strongly interacts with some surfactants.

[0005] Japanese Patent Application Publication No. 58-216222 Japanese Patent Application Publication No. 61-69023 Japanese Patent Application Publication No. 6-503373 Japanese Patent Application Publication No. 2014-40598

[0006] However, the plasma treatment proposed in Patent Document 1 requires an extremely large-scale device and has problems such as complicated conditions for forming a coating. Furthermore, the method proposed in Patent Document 2 has the problem that the water wettability and surface lubricity of the contact lens cannot be maintained over the long term. Furthermore, the method proposed in Patent Document 3 has the problem that the amphiphilic substance is copolymerized with other raw materials of the contact lens, which affects the water content and mechanical properties of the contact lens and prevents the contact lens from maintaining suitable physical properties. Furthermore, the method proposed in Patent Document 4 has the problem that the surfactant is released during long-term storage or due to friction and tear replacement during wear on the eye, resulting in a decrease in the surface hydrophilicity of the contact lens.

[0007] As a result of extensive research into solving the above problems, the present inventors have found that the above problems can be solved, for example, by the following methods, and have arrived at the present invention.

[0008] That is, the present invention has the following aspects: [1] A silicone hydrogel containing water, wherein in a dried body obtained by removing water from the silicone hydrogel, the ratio (A' / B') of the average value (A') of the O / Si concentration ratios from the first to third measurement points to the average value (B') of the O / Si concentration ratios from the fourteenth to sixteenth measurement points is 1.20 or more. (Here, the O / Si concentration ratio is the ratio of the proportion of oxygen atoms to the proportion of silicon atoms, calculated from the proportion of oxygen atoms (atm %) and the proportion of silicon atoms (atm %) on the surface of the dried body determined by depth profiling using X-ray photoelectron spectroscopy. The O / Si concentration ratio is determined by etching the dried body from the outermost surface in the thickness direction by irradiating it with an Ar ion beam generated under conditions of ionization energy of 3000 eV, sequentially setting a first measurement point (etching time: 0 second, outermost surface of the dried body) and a second measurement point (etching time: 50 seconds) every 50 seconds, up to a 16th measurement point (etching time: 750 seconds), for a total of 16 measurement points, and determining the O / Si concentration ratio at each measurement point.) [2] The silicone hydrogel of [1], wherein the silicone hydrogel further comprises a cured product of a curable composition, and the curable composition comprises a silicone-based (meth)acrylate (A), a hydrophilic monomer (B), and a surfactant (C). [3] The silicone hydrogel of [2], wherein the hydrophilic monomer (B) contains a monomer having one or more selected from a hydroxyl group, an amino group, a carboxyl group, a (meth)acryloyl group, an ionic group, an amide structure, and an alkyleneoxy structure in the molecule. [4] The silicone hydrogel of [2] or [3], wherein the hydrophilic monomer (B) contains at least one selected from N-vinyl-2-pyrrolidone and N,N-dimethylacrylamide. [5] The silicone hydrogel of any of [2] to [4], wherein the surfactant (C) contains a non-polymerizable surfactant. [6] The silicone hydrogel of any of [2] to [4], wherein the surfactant (C) contains a sugar-based surfactant. [7] The silicone hydrogel of [6], wherein the sugar-based surfactant contains a sugar fatty acid ester.[8] The silicone hydrogel of any one of [1] to [7], having a single-layer structure in which the difference in O / Si concentration ratio between adjacent measurement points between the first measurement point and the sixteenth measurement point is 10 or less. [9] A contact lens having the silicone hydrogel of any one of [1] to [8].

[10] A method for producing the silicone hydrogel of [1], comprising the following steps (1), (2), and (4), and optionally including (3): (1): preparing a curable composition containing a silicone-based (meth)acrylate (A), a hydrophilic monomer (B), and one or more surfactants (C). (2): molding the curable composition prepared in (1) using a hydrophobic mold to obtain a cured product. (3): swelling the cured product obtained in (2) with water. (4): washing the silicone hydrogel obtained in (3).

[11] The method for producing

[10] , wherein the surfactant (C) comprises a non-polymerizable surfactant.

[12] The method for producing

[10] , wherein the surfactant (C) comprises a sugar-based surfactant.

[13] The manufacturing method of

[12] , wherein the sugar-based surfactant contains a sugar fatty acid ester.

[14] The manufacturing method of any one of

[10] to

[13] , wherein the hydrophobic mold is a mold made of polyolefin.

[15] The manufacturing method of any one of

[10] to

[14] , wherein the silicone hydrogel is not subjected to plasma treatment.

[16] A manufacturing method of a contact lens having the silicone hydrogel of [1], comprising manufacturing the silicone hydrogel by the manufacturing method of any one of

[10] to

[15] .

[0009] The silicone hydrogel of the present invention has excellent surface hydrophilicity and transparency, making it particularly useful as an ophthalmic device such as a contact lens, an intraocular lens, an artificial cornea, etc. According to the method for producing the silicone hydrogel of the present invention, even when a hydrophobic mold such as polypropylene is used, a silicone hydrogel having excellent surface hydrophilicity that is stable for a long period of time can be obtained without requiring surface treatment such as plasma treatment.

[0010] The present invention relates to a contact lens using a silicone hydrogel, and is a method for analyzing the contact lens using the silicone hydrogel of the present invention.

[0011] Hereinafter, embodiments of the present invention will be described. The following embodiments are merely examples for explaining the present invention, and are not intended to limit the present invention to these embodiments. The present invention can be implemented in various forms without departing from the spirit of the present invention.

[0012] In the present invention, "(meth)acrylate" is a general term for acrylate and methacrylate.

[0013] <Silicone Hydrogel> One embodiment of the silicone hydrogel of the present invention contains water. In this silicone hydrogel, in a dried body obtained by removing the water contained in the silicone hydrogel from the silicone hydrogel, the ratio (A' / B') of the average O / Si concentration ratio (A') at the first to third measurement points to the average O / Si concentration ratio (B') at the fourteenth to sixteenth measurement points described below is 1.20 or more. Here, the O / Si concentration ratio is the ratio of the proportion of oxygen atoms to the proportion of silicon atoms, calculated from the proportion of oxygen atoms (atm%) and the proportion of silicon atoms (atm%) at the surface of the dried body determined by depth profiling using X-ray photoelectron spectroscopy. The O / Si concentration ratio was determined by setting a first measurement point (etching time: 0 seconds, outermost surface of the cured product) and a second measurement point (etching time: 50 seconds) every 50 seconds when the dried product was etched in the thickness direction from the outermost surface by irradiating the dried product with an Ar ion beam generated under the condition of an ionization energy of 3000 eV, up to the 16th measurement point (etching time: 750 seconds), for a total of 16 measurement points, and determining the O / Si concentration ratio at each measurement point.

[0014] In the present invention, the term "dried product" refers to a silicone hydrogel obtained by removing water from the silicone hydrogel. The silicone hydrogel may be a mixture of a cured product of a curable composition and at least water, and is typically obtained by swelling the cured product of the curable composition with a water-containing solvent, preferably water. Water can be removed from the silicone hydrogel by a conventional method so that the water content is 3% by mass or less, preferably 2% by mass or less, more preferably 1% by mass or less, and even more preferably 0.1% by mass or less. For example, drying using a dryer or freeze-drying can be used.

[0015] Another embodiment of the silicone hydrogel of the present invention includes water and a cured product of a curable composition. Specifically, the cured product of the curable composition is swollen with water. In a dried product of the silicone hydrogel obtained by removing the water contained in the silicone hydrogel from the silicone hydrogel, the ratio (A' / B') of the average O / Si concentration ratios (A') from the first to third measurement points to the average O / Si concentration ratios (B') from the fourteenth to sixteenth measurement points may be 1.20 or greater.

[0016] The concentration ratio A' / B' is preferably 1.40 or more, more preferably 1.60 or more. If the concentration ratio A' / B' is equal to or greater than the lower limit, segregation of silicone to the surface is suppressed, and the surface is less likely to become a hydrophobic silicone hydrogel. Although a high concentration ratio A' / B' is preferred, from the viewpoint of being able to reduce the amount of surfactant used during production, it may be 3.00 or less, 2.80 or less, or 2.60 or less.

[0017] The concentration ratio A' / B' can be adjusted, for example, by the type of surfactant (C) described below and the concentration of the surfactant (C) in the cured composition.

[0018] Depth profiling of silicone hydrogel using X-ray photoelectron spectroscopy can be performed using the following procedure. FIG. 1 is a schematic diagram illustrating an analysis method using X-ray photoelectron spectroscopy (XPS). In FIG. 1, reference numeral 10 denotes an X-ray photoelectron spectroscopy instrument, reference numeral 20 denotes a gas ion beam instrument, reference numeral 30 denotes a sample stage, and reference numeral 100 denotes a sample (silicone hydrogel). The silicone hydrogel surface is thoroughly wiped clean and then thoroughly dried, for example, by freeze-drying. X-ray analysis using XPS is performed by irradiating X-rays from the X-ray photoelectron spectroscopy instrument 10 onto a sample 100 placed on the upper surface 30a of the sample stage 30, as shown in FIG. 1 . By analyzing the kinetic energy of photoelectrons excited by the photoelectric effect, information such as the atomic concentration and atomic bonding state near the surface of the sample 100 can be obtained. Furthermore, by performing XPS measurements while etching, information on the atomic concentration in the depth direction of the sample can be obtained. In the present invention, etching is performed by irradiating the sample with an Ar ion beam from an argon gas ion beam (Ar-IB). The irradiation direction is tilted by θ° (0°<θ<90°) with respect to the normal direction of the sample surface (see Figure 1). The concentration distribution of each atom is calculated by measuring the number of atoms of carbon, oxygen, nitrogen, silicon, and fluorine contained in the cured product, and sodium, chlorine, and phosphorus derived from the phosphate buffer solution, and expressing the percentage of the total number as 100 atomic %.

[0019] The silicone hydrogel of the present invention preferably has a contact angle of 90° or less after being washed five times with water at 90° C. The lower the contact angle of the silicone hydrogel, the more preferable it is, and it may even be 0°. Here, the contact angle of the silicone hydrogel means the contact angle between the silicone hydrogel and a water droplet.

[0020] The total light transmittance of the silicone hydrogel is preferably 90% or more, more preferably 92% or more, and even more preferably 93% or more. The higher the total light transmittance, the better, and it may even be 100%.

[0021] The silicone hydrogel of the present invention preferably has a haze, measured in accordance with JIS K7136:2000 "Determination of haze of plastics - transparent materials," of 0.1 or more and 20 or less, more preferably 0.2 or more and 15 or less, and even more preferably 0.3 or more and 10 or less. When the haze is at least the above lower limit, the handleability is excellent, and when the haze is at most the above upper limit, the transparency is excellent.

[0022] The silicone hydrogel of the present invention can also be obtained in a multilayer structure in which multiple phases with different constituent components are laminated. It can also be obtained as a single layer structure by continuously changing the O / Si concentration ratio. From the viewpoint of ease of production and production cost, it is preferable to obtain a single layer structure by continuously changing the O / Si concentration ratio. Unlike a multilayer structure, a single layer structure does not have boundaries between layers. Therefore, the structure does not have a location where the constituent components change significantly due to the boundaries between layers. That is, in a dried body obtained by removing water from the silicone hydrogel, the single layer structure has an O / Si concentration ratio difference between adjacent measurement points from the first measurement point to the sixteenth measurement point of 10 or less, preferably 5 or less, more preferably 3 or less, between any of the measurement points.

[0023] <Curable Composition> One embodiment of the curable composition of the present invention contains a silicone-based (meth)acrylate (A), a hydrophilic monomer (B), and a surfactant (C). Hereinafter, each component constituting the curable composition will be described.

[0024] <Silicone-based (meth)acrylate (A)> The silicone-based (meth)acrylate (A) used in the present invention contributes to, for example, the oxygen permeability, transparency, mechanical strength, and hydrophilicity of the silicone hydrogel. The silicone-based (meth)acrylate (A) preferably has a siloxanyl group in the molecule. The silicone-based (meth)acrylate (A) may be any of a monomer, a macromonomer, and a prepolymer.

[0025] Examples of the silicone (meth)acrylate (A) include trimethylsiloxydimethylsilylmethyl (meth)acrylate, trimethylsiloxydimethylsilylpropyl (meth)acrylate, methylbis(trimethylsiloxy)silylpropyl (meth)acrylate, tris(trimethylsiloxy)silylpropyl (meth)acrylate, mono[methylbis(trimethylsiloxy)siloxy]bis(trimethylsiloxy)silylpropyl (meth)acrylate, tris[methylbis(trimethylsiloxy)siloxy]silylpropyl (meth)acrylate, methylbis(trimethylsiloxy)silylpropyl glyceryl (meth)acrylate, and tris(trimethylsiloxy)silylpropyl. propyl glyceryl (meth)acrylate, mono[methylbis(trimethylsiloxy)siloxy]bis(trimethylsiloxy)silylpropyl glyceryl (meth)acrylate, trimethylsilylethyl tetramethyldisiloxypropyl glyceryl (meth)acrylate, trimethylsiloxydimethylsilylpropyl glyceryl (meth)acrylate, methylbis(trimethylsiloxy)silylethyl tetramethyldisiloxymethyl (meth)acrylate, tetramethyltriisopropylcyclotetrasiloxanylpropyl (meth)acrylate, tetramethyltriisopropylcyclotetrasiloxybis(trimethylsiloxy)silylpropyl (meth)acrylate.

[0026] Further examples of the silicone-based (meth)acrylate (A) include the compounds (A1) and (A2) described below.

[0027] [Compound (A1)] The compound (A1) is a silicone-based (meth)acrylate represented by the following formula (1).

[0028]

[0029] In formula (1), R １ represents a hydrogen atom or a methyl group. ２ ~R ７each independently represents an alkyl group, an alkoxy group, or an alkoxyalkyl group which may have a substituent. j is a natural number from 1 to 10, k is a natural number from 1 to 30, and l is a natural number from 1 to 3. When l is 1, multiple R ２ may be the same or different, and when l is 2 or more, multiple siloxanyl groups shown in [ ] may be the same or different. When k is 2 or more, multiple (-Si(R ３ ) (R ４ The groups represented by —O—) may be the same or different.

[0030] R １ is preferably a methyl group because it is readily available.

[0031] R ２ ~R ７ Examples of the alkyl group in the formula (I) include branched or linear alkyl groups having 1 to 22 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a t-butyl group, an i-butyl group, a pentyl group (amyl group), an i-pentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, an octyl group, an i-octyl group, a nonyl group, an i-nonyl group, a decyl group, an i-decyl group, an undecyl group, a dodecyl group (lauryl group), a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group (stearyl group), an i-octadecyl group, a nonadecyl group, an icosyl group, and a docosyl group.

[0032] R ２ ~R ７ The alkoxy group includes branched or straight chain alkoxy groups having 1 to 22 carbon atoms, and specific examples include methoxy, ethoxy, propoxy, and butoxy groups.

[0033] R ２ ~R ７Examples of the alkoxyalkyl group include branched or linear alkoxyalkyl groups having 1 to 22 carbon atoms, and specific examples include a methoxymethyl group, a methoxyethyl group, a methoxypropyl group, a methoxybutyl group, an ethoxymethyl group, an ethoxyethyl group, an ethoxypropyl group, an ethoxybutyl group, a propoxymethyl group, a propoxyethyl group, a propoxypropyl group, a propoxybutyl group, a butoxymethyl group, a butoxyethyl group, a butoxypropyl group, and a butoxybutyl group.

[0034] R ２ ~R ７ The alkyl group, alkoxy group, and alkoxyalkyl group in the formula (I) may each be substituted with one or more halogen atoms. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine.

[0035] R ２ is preferably an unsubstituted or substituted alkyl group, more preferably a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a t-butyl group, or an i-butyl group, and even more preferably a methyl group. ３ ~R ７ are each independently preferably an alkyl group or a halogenated alkyl group, and more preferably a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a t-butyl group, an i-butyl group, a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a 1-fluoroethyl group, a 2-fluoroethyl group, a 1,1-difluoroethyl group, a 1,2-difluoroethyl group, a 2,2-difluoroethyl group, a 2,2,2-trifluoroethyl group, a 3,3,3-trifluoropropyl group, or a 1-trifluoromethylethyl group.

[0036] The oxygen permeability of silicone hydrogel is improved, ３ ~R ７ At least one of the groups is preferably a halogenated alkyl group, more preferably a fluorinated alkyl group.

[0037] j is a natural number from 1 to 10, and preferably from 1 to 5. k is a natural number from 1 to 30, and preferably from 1 to 20. Compound (A1) may be a mixture of multiple compounds having different k's. l is a natural number from 1 to 3, and preferably 1 or 2.

[0038] The compound (A1) is preferably at least one of the following compounds.

[0039] R in formula (1) １ ~R ６ is a methyl group, and R ７ is an n-butyl group, j is 3, and l is 1 ("Silaplane (registered trademark) FM-0711," "Silaplane (registered trademark) FM-0721," and "Silaplane (registered trademark) FM-0725," manufactured by JNC Corporation, and "MCR-M07" and "MCR-M11," manufactured by Gelest).

[0040] R in formula (1) １ , R ２ , R ４ and R ６ is a methyl group, and R ３ and R ５ is a 3,3,3-trifluoropropyl group, and R ７ is an n-butyl group, j is 3, and l is 1 ("MFR-M15" manufactured by Gelest)

[0041] R in formula (1) １ ~R ６ is a methyl group, and R ７ is an n-butyl group, j is 3, and l is 2 ("MCS-M11" manufactured by Gelest)

[0042] R in formula (1) １ ~R ６ is a methyl group, and R ７ is a methoxypropyl group, j is 3, and l is 2 ("MCS-MX11" manufactured by Gelest)

[0043] R in formula (1) １ , R ２ , R ４ and R ６ is a methyl group, and R ３ and R ５is a 3,3,3-trifluoropropyl group, and R ７ is an n-butyl group, j is 3, and l is 2 ("MFS-M15" manufactured by Gelest)

[0044] [Compound (A2)] The compound (A2) is a silicone-based (meth)acrylate represented by the following formula (2).

[0045]

[0046] In formula (2), R ８ represents a hydrogen atom or a methyl group. ９ represents a single bond or an alkylene group, an alkylene oxide group, a polyalkylene oxide group, or an alkylene-oxy-alkylene group which may have a substituent. １０ ~R １３ each independently represents an alkyl group, an alkoxy group, or an alkoxyalkyl group which may have a substituent. m is a natural number from 1 to 10, and n is a natural number from 1 to 3. When n is 1, multiple R １０ may be the same or different. When n is 2 or more, a plurality of —O—Si(R １１ ) (R １２ ) (R １３ ) may be the same or different.

[0047] R ８ is preferably a methyl group because it is readily available.

[0048] R ９ The alkylene group, alkylene oxide group, polyalkylene oxide group, and alkylene-oxy-alkylene group in the above formula (1) are ２ ~R ７ The divalent substituent is the same as the alkyl group, alkoxy group, or alkoxyalkyl group described in the above. The surface hydrophilicity and transparency of the silicone hydrogel are improved, so R ９ is preferably a single bond, an unsubstituted or substituted alkylene oxide group, or an alkylene-oxy-alkylene group, and more preferably a single bond, or an unsubstituted or substituted alkylene oxide group.

[0049] R １０ ~R１３ The alkyl group, alkoxy group, and alkoxyalkyl group in the formula (1) are ２ ~R ７ It is the same as that explained in R. １０ ~R １３ The alkyl group, alkoxy group and alkoxyalkyl group in the formula (I) may each be substituted with one or more halogen atoms.

[0050] R １０ ~R １３ is preferably an unsubstituted or substituted alkyl group, more preferably a methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, t-butyl group or i-butyl group, and even more preferably a methyl group.

[0051] m is a natural number from 1 to 10, and preferably from 1 to 5. n is a natural number from 1 to 3, and preferably 2 or 3, as this improves the surface hydrophilicity and transparency of the silicone hydrogel.

[0052] As the compound (A2), at least one of the following compounds is preferred.

[0053] R in formula (2) ８ is a methyl group, and R ９ is a single bond, and R １１ ~R １３ is a methyl group, m is 3, and n is 3 (TRIS, "SIM6487.6" manufactured by Gelest)

[0054] R in formula (2) ８ is a methyl group, and R ９ is CH ２ CH(OH)CH ２ O and R １０ ~R １３ is a methyl group, m is 3, and n is 2 (SIMMA, "SIM6481.15" manufactured by Gelest, "BX-SiGMMA" manufactured by Bimax)

[0055] The silicone (meth)acrylate (A) may be used alone or in combination of two or more. Among these, it is preferred to use the compounds (A1) and (A2) in combination, as this improves the surface hydrophilicity, transparency, and flexibility of the silicone hydrogel.

[0056] When the silicone-based (meth)acrylate (A) contains one or both of the compound (A1) and the compound (A2), the total content of the compound (A1) and the compound (A2) in the silicone-based (meth)acrylate (A) may be 50% by mass or more, 80% by mass or more, 90% by mass or more, or even 100% by mass.

[0057] <Hydrophilic Monomer (B)> The hydrophilic monomer (B) used in the present invention contributes to the hydrophilicity of the silicone hydrogel, for example. The hydrophilic monomer (B) preferably contains a monomer having one or more selected from a hydroxyl group, an amino group, a carboxyl group, a (meth)acryloyl group, an ionic group, an amide structure, and an alkyleneoxy structure in the molecule. The hydrophilic monomer (B) may be a monomer, a macromonomer, or a prepolymer.

[0058] Examples of the hydrophilic monomer (B) include monomers having a hydroxyl group such as 2-hydroxyethyl (meth)acrylate, 2,3-dihydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; monomers having an amino group such as N,N-dimethylaminoethyl (meth)acrylate; monomers having a carboxyl group such as (meth)acryloxyethyl succinic acid; monomers having an ionic group such as (3-(meth)acrylamidopropyl)trimethylammonium chloride, (meth)acryloxyethyldimethylbenzylammonium chloride, 3-((meth)acrylamido)propyldimethylbenzylammonium chloride, (meth)acryloylcholine chloride, and 2-(meth)acryloyloxyethylphosphorylcholine; Monomers having an amide structure, such as N-vinyl-2-pyrrolidone, N,N-dimethylacrylamide, N-hydroxymethyl(meth)acrylamide, N-(2-hydroxyethyl)(meth)acrylamide, (meth)acrylamide, N-vinylacetamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, 4-(meth)acryloylmorpholine, and (meth)acrylamide; and monomers having an alkylene oxide structure, such as polyethylene glycol (meth)acrylate.

[0059] The hydrophilic monomer (B) may be used alone or in combination of two or more. 2-hydroxyethyl (meth)acrylate is preferred as the hydrophilic monomer (B) because it improves hydrophilicity and is readily available. In another embodiment, N-vinyl-2-pyrrolidone and N,N-dimethylacrylamide are preferred as the hydrophilic monomer (B) because they can impart flexibility and mechanical strength, and a mixture of these may also be used.

[0060] When the hydrophilic monomer (B) contains a monomer having one or more selected from a hydroxyl group, an amino group, a carboxyl group, a (meth)acryloyl group, an ionic group, an amide structure, and an alkyleneoxy structure in the molecule, the total content of the monomers having one or more selected from a hydroxyl group, an amino group, a carboxyl group, a (meth)acryloyl group, an ionic group, an amide structure, and an alkyleneoxy structure in the molecule in the hydrophilic monomer (B) may be 50% by mass or more, 80% by mass or more, 90% by mass or more, or even 100% by mass.

[0061] When the hydrophilic monomer (B) contains one, two, or three of N,N-dimethylacrylamide, hydroxyethyl methacrylate, and N-vinyl-2-pyrrolidone, the total content of N,N-dimethylacrylamide, hydroxyethyl methacrylate, and N-vinyl-2-pyrrolidone in the hydrophilic monomer (B) may be 50% by mass or more, 80% by mass or more, 90% by mass or more, or even 100% by mass.

[0062] <Surfactant (C)> The surfactant (C) used in the present invention pseudo-hydrophilizes the hydrophobic mold used during curing of the curable composition, suppressing segregation of the hydrophobic silicone (meth)acrylate (A) to the surface of the cured product, thereby enhancing the hydrophilicity of the silicone hydrogel surface. While the details are unclear, the following mechanism is presumed. Specifically, the surfactant (C) added to the curable composition adsorbs onto the mold surface, covering the hydrophobic surface of the mold with the surfactant. Because the hydrophobic portion of the surfactant adsorbs toward the mold surface, the mold surface becomes pseudo-hydrophilic. As a result, the concentration of hydrophilic monomer in the curable composition becomes relatively higher near the pseudo-hydrophilized mold surface. Polymerization under this condition produces a cured product (three-dimensionally crosslinked polymer) in which the concentration of hydrophilic monomer units is relatively higher near the surface than in the interior. Silicone hydrogels containing the cured product produced by this method tend to exhibit stable surface hydrophilicity.

[0063] The surfactant (C) may be either nonionic or ionic. From the viewpoint of surface hydrophilization performance and because the surfactant (C) is eluted during washing of the silicone hydrogel described below, the HLB value of the surfactant (C) is preferably 3 to 19, more preferably 5 to 18, and even more preferably 10 to 17.

[0064] As the surfactant (C), surfactants having a polyoxyethylene group, sugar-based surfactants, and surfactants derived from biological materials are preferred. The surfactant (C) preferably contains at least a non-polymerizable surfactant that does not have a polymerized structure in its structure. Patent Document 3 has a problem in that the amphiphilic substance is copolymerized with other raw materials of the contact lens, which affects the water content and mechanical properties of the contact lens, preventing the contact lens from maintaining suitable properties. In contrast, when the surfactant (C) contains a non-polymerizable surfactant, the surfactant can be removed from the contact lens by washing, as described below, thereby reducing the impact on other components.

[0065] As the non-polymerizable surfactant, sugar-based surfactants and surfactants derived from biological materials (excluding polymerizable surfactants) are preferred, with sugar-based surfactants being more preferred. In one embodiment, surfactant (C) may contain a non-polymerizable surfactant, or may contain a non-polymerizable surfactant and a polymerizable surfactant. In another embodiment, surfactant (C) may contain a sugar-based surfactant, or may contain a sugar-based surfactant and a surfactant having a polyoxyethylene group.

[0066] Examples of surfactants having a polyoxyethylene group include polyoxyethylene alkyl ethers such as polyoxyethylene hydrogenated castor oils, polyoxyethylene castor oil, polyoxyethylene glycerin fatty acid esters, and polyoxyethylene lauryl ether; polyoxyethylene polyoxypropylene copolymers, polyoxyethylene polysiloxane ether block copolymers, polyoxyethylene polyoxypropylene ethylenediamine, polyoxyethylene polyoxypropylene alkyl ethers, polyoxyethylene sorbitan fatty acid esters (polysorbates) such as polyoxyethylene sorbitan monooleate (e.g., polysorbate 80), polyoxyethylene sorbit fatty acid esters, polyoxyethylene alkylphenyl ethers, and polyoxyethylene alkylphenyl ether formaldehyde condensates such as tyloxapol, polyoxyethylene sterols, polyoxyethylene hydrogenated sterols, and polyoxyethylene fatty acid esters such as polyethylene glycol monostearate, polyoxyethylene lanolin alcohol, polyoxyethylene alkylamines, polyoxyethylene alkylamides, and polyoxyethylene alkyl ether phosphates.

[0067] Sugar-based surfactants are nonionic surfactants with sugar as the hydrophilic group. Examples of sugar-based surfactants include sugar fatty acid esters formed by an ester bond between a sugar and a fatty acid, and alkyl glycosides formed by a glycosidic bond between a sugar and a higher alcohol, with sugar fatty acid esters being preferred. The fatty acid in the sugar fatty acid ester is preferably a saturated fatty acid.

[0068] Examples of sugar fatty acid esters include sucrose fatty acid esters, sucrose benzoate esters, sucrose acetate esters, sorbitan fatty acid esters, and glucose esters, with sucrose fatty acid esters being preferred.

[0069] The number of carbon atoms in the constituent fatty acids of the sugar fatty acid ester is not particularly limited, but is preferably 12 to 22, and more preferably 12 to 18. Examples of saturated fatty acids having 12 to 22 carbon atoms include lauric acid (12), myristic acid (14), pentadecylic acid (15), palmitic acid (16), margaric acid (17), and stearic acid (18). Here, the numbers in parentheses indicate the number of carbon atoms in each saturated fatty acid.

[0070] The number of fatty acid ester groups in a sugar fatty acid ester varies depending on the number of hydroxyl groups capable of forming an ester bond in the molecular structure of the sugar, which is the hydrophilic group, and is, for example, 1 to 8 for sucrose fatty acid esters and 2 to 4 for sorbitan fatty acid esters. The HLB value of a sugar fatty acid ester can be adjusted by the number of fatty acid ester groups.

[0071] Surfactants derived from biological materials refer to surfactants that use biological materials such as hyaluronic acid, vitamins, etc. as raw materials. Examples of surfactants derived from biological materials include hyaluronic acid derivatives in which hydrophobic groups are attached via a glycerin skeleton to some of the hydrophilic groups of low-molecular-weight hyaluronic acid obtained by hydrolyzing high-molecular-weight hyaluronic acid, such as hydrolyzed alkyl hyaluronate (having 12-13 carbon atoms) glyceryl; vitamin C derivatives such as L-ascorbyl paramitate, L-ascorbyl stearate, 2,6-dibutyryl-L-ascorbic acid, and 2-O-α-D-glucopyranosyl-L-ascorbic acid; and vitamin E derivatives such as DL-α-tocopherol acetate, sodium DL-α-tocopheryl phosphate, and D-α-tocopherol succinate.

[0072] The surfactant (C) may be used alone or in combination of two or more kinds.

[0073] From the viewpoint of increasing the concentration ratio A' / B', the surfactant (C) is preferably a sugar-based surfactant, more preferably a sugar fatty acid ester, and even more preferably a sucrose fatty acid ester.

[0074] When surfactant (C) contains a non-polymerizable surfactant, the total content of non-polymerizable surfactants in surfactant (C) may be 30% by mass or more, 50% by mass or more, 60% by mass or more, 80% by mass or more, or even 100% by mass. When surfactant (C) contains a sugar-based surfactant, the total content of sugar-based surfactants in surfactant (C) may be 30% by mass or more, 50% by mass or more, 60% by mass or more, 80% by mass or more, or even 100% by mass. When surfactant (C) contains a sugar fatty acid ester, the total content of sugar fatty acid esters in surfactant (C) may be 30% by mass or more, 50% by mass or more, 60% by mass or more, 80% by mass or more, or even 100% by mass. When the surfactant (C) contains a polymerizable surfactant, the total content of the polymerizable surfactants in the surfactant (C) may be 70% by mass or less, 50% by mass or less, 40% by mass or less, 20% by mass or less, or 0% by mass.

[0075] The curable composition of the present invention may further contain optional components in addition to the silicone-based (meth)acrylate (A), the hydrophilic monomer (B), and the surfactant (C), such as a crosslinking agent (D), a polymerization initiator (E), and other components.

[0076] <Crosslinking Agent (D)> The curable composition of the present invention may contain a crosslinking agent (D) for the purposes of improving the solvent resistance of the resulting silicone hydrogel and adjusting the elastic modulus, water content, etc. The crosslinking agent (D) preferably has two or more polymerizable unsaturated groups.

[0077] Examples of the crosslinking agent (D) include (meth)acrylate-based crosslinking agents such as 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, allyl methacrylate, trimethylolpropane tri(meth)acrylate, (2-allyloxy)ethyl methacrylate, and 2-(2-vinyloxyethoxy)ethyl (meth)acrylate; vinyl ether-based crosslinking agents such as ethylene glycol divinyl ether, diethylene glycol divinyl ether, and triethylene glycol divinyl ether; allyl ether-based crosslinking agents such as triethylene glycol diallyl ether and tetraethylene glycol diallyl ether; and methylenebisacrylamide. As the crosslinking agent (D), (meth)acrylate-based crosslinking agents are preferred, and ethylene glycol di(meth)acrylate and polyethylene glycol di(meth)acrylate are more preferred.

[0078] The crosslinking agent (D) may be used alone or in combination of two or more. The content of the crosslinking agent (D) in the curable composition is preferably 0.1 to 10 mass%, more preferably 0.5 to 5 mass%. Within this range, the moldability and solvent resistance of the silicone hydrogel are improved.

[0079] <Polymerization initiator (E)> The curable composition of the present invention may contain a polymerization initiator (E) in order to effectively proceed with the polymerization reaction. Examples of the polymerization initiator include known photopolymerization initiators and thermal polymerization initiators.

[0080] Examples of photopolymerization initiators include benzil, benzophenone and derivatives thereof, thioxanthones, benzil dimethyl ketals, α-hydroxyalkylphenones, α-hydroxyacetophenones, hydroxyketones, aminoalkylphenones, acylphosphine oxides, and oxime ester compounds. α-Hydroxyalkylphenones are preferred because they are less likely to yellow during curing and produce a transparent cured product.

[0081] Examples of the thermal polymerization initiator include known organic peroxides and azo compounds.

[0082] The polymerization initiator (E) may be used alone or in combination of two or more. The content of the polymerization initiator (E) in the curable composition is preferably 0.1 to 3 parts by mass, more preferably 0.1 to 2 parts by mass, and even more preferably 0.2 to 1 part by mass, relative to 100 parts by mass of the total monomer components in the curable composition. Within the above range, the polymerization rate is high, and decomposition products derived from the polymerization initiator (E) are less likely to remain.

[0083] <Other Components> The curable composition of the present invention can contain, for example, other monomers (monomers other than the silicone-based (meth)acrylate (A) and the hydrophilic monomer (B)), polymerizable UV absorbers, and polymerizable dyes (colorants) within a range that does not impair the object of the present invention.

[0084] <Ratio of Curable Composition> The content of the silicone (meth)acrylate (A) in the curable composition is preferably 4 to 50 mass %, more preferably 10 to 40 mass %. Within this range, the surface hydrophilicity, transparency, and oxygen permeability of the silicone hydrogel are improved.

[0085] The content of the hydrophilic monomer (B) in the cured composition is preferably 5 to 95% by mass, more preferably 20 to 90% by mass, in order to provide a silicone hydrogel with good surface hydrophilicity and transparency.

[0086] The content of surfactant (C) in the curable composition is preferably 1% by mass or more, more preferably 1 to 12% by mass, and even more preferably 1 to 10% by mass. If the content is 1% by mass or more, sufficient hydrophilicity of the molded silicone hydrogel is easily obtained, and if the content is 12% by mass or less, the silicone hydrogel is less likely to become cloudy.

[0087] <Method for Producing Silicone Hydrogel> The method for producing a silicone hydrogel of the present invention includes the following steps (1) to (4).

[0088] <Step (1)> A step of preparing a curable composition containing a silicone-based (meth)acrylate (A), a hydrophilic monomer (B), and one or more surfactants (C).

[0089] The silicone-based (meth)acrylate (A), hydrophilic monomer (B), and surfactant (C) components are as described above. The curable composition of the present invention can be prepared, for example, by adding the components in any order or all at once to a stirring (mixing) device and stirring (mixing) at a temperature of 10 to 50°C until the mixture becomes uniform.

[0090] <Step (2)> A step of molding the curable composition prepared in step (1) using a hydrophobic mold to obtain a cured product.

[0091] The hydrophobic mold is a mold used when filling the curable composition to cause a polymerization reaction, and has a hydrophobic surface. The hydrophobic mold is preferably a mold made of polyolefin, more preferably a mold made of polypropylene.

[0092] A curable composition is filled into a hydrophobic mold and polymerized to obtain a cured product. The polymerization reaction can be promoted by irradiating the curable composition with active energy rays or by heating the curable composition.

[0093] When the polymerization reaction is promoted by irradiation with active energy rays, examples of the active energy rays include ultraviolet rays and electron beams. Examples of the ultraviolet light source include high-pressure mercury lamps. The amount of ultraviolet energy is 0.1 to 10 J / cm. ２ When the polymerization reaction is carried out by heating, the temperature and heating time are not particularly limited, but the temperature can be 60 to 140° C. and the time can be 0.1 to 12 hours.

[0094] The polymerization reaction may be carried out in the air, but may also be carried out in an inert gas atmosphere such as nitrogen or argon in order to improve the polymerization rate of the monomer.

[0095] After the polymerization reaction, the cured product can be removed in a dry state by deforming the hydrophobic mold. Alternatively, the cured product can be immersed together with the hydrophobic mold in a solvent (e.g., water, methanol, ethanol, 1-propanol, 2-propanol, or a mixture thereof) to swell and remove from the hydrophobic mold. In this case, if the solvent contains water, the product removed will be a silicone hydrogel. It is preferable to remove the cured product in a dry state after the polymerization reaction without using a solvent.

[0096] <Step (3)> A step of swelling the cured product obtained in step (2) with water.

[0097] If the cured product is removed in a dry state in step (2), the resulting cured product can be immersed in a water-containing solvent (water or a mixture of water and alcohols (methanol, ethanol, 1-propanol, 2-propanol)) to swell, thereby obtaining a silicone hydrogel. Note that step (3) may be omitted and step (4) may be carried out. If the cured product is immersed in a solvent in step (2), swelled, and then removed, step (3) may be omitted.

[0098] <Step (4)> A step of washing the silicone hydrogel or cured product obtained in step (3).

[0099] The obtained silicone hydrogel or cured product may be a mixture of two or more surfactants (C), unreacted monomer components (unreacted materials), residues of each component, by-products, etc. Therefore, for example, after solvation, washing is performed by repeatedly replacing the solvent with a new solvent. Examples of solvents used for washing include water, methanol, ethanol, 1-propanol, 2-propanol, and mixtures thereof, and a buffer solution such as a phosphate buffer may be used as the water. Washing is preferably performed multiple times, and solvents of different types or concentrations may be used for each washing. It is preferable to use a solvent containing water.

[0100] The washing procedure is not particularly limited. For example, a silicone hydrogel may be placed in a solution of 2-propanol and phosphate buffer in a 1:1 ratio heated to 60°C, and immersed for a desired period of time, followed by immersion in a phosphate buffer solution preheated to 60°C for a desired period of time. This washing procedure allows unreacted substances, surfactant residues, by-products, and the like contained in the silicone hydrogel to be expelled to the outside. Specifically, the method described in the Examples can be used.

[0101] The silicone hydrogel or cured product obtained in step (3) can be further hydrated. Hydration is preferably carried out by immersing the cured product in water or physiological saline at a temperature of 10 to 90°C for 10 minutes or more. The obtained silicone hydrogel may be sterilized under high temperature and high pressure. Depending on the shape and size of the silicone hydrogel, it may be sterilized, for example, in an autoclave at 121°C and 2 atmospheres for 20 minutes.

[0102] <Mechanism of Action> According to the method for producing a silicone hydrogel of the present invention, the one or more surfactants (C) contained in the curable composition pseudo-hydrophilize the surface (inner wall surface) of the hydrophobic mold, causing the hydrophilic monomer (B) to be unevenly distributed on the surface of the silicone hydrogel, making it possible to produce a silicone hydrogel that has a highly hydrophilic surface even after the surfactant (C) is removed in the washing step.

[0103] This means that the surface hydrophilicity of the silicone hydrogel is unlikely to decrease due to friction or washing when it is actually used. Based on the above, the silicone hydrogel of the present invention is characterized by the fact that it does not require surface treatment for hydrophilization, such as plasma treatment, as is required in the prior art.

[0104] <Contact Lenses> The silicone hydrogel of the present invention has excellent surface hydrophilicity and transparency, making it particularly useful as an ophthalmic device such as a contact lens, an intraocular lens, or an artificial cornea.

[0105] Fig. 2 is a perspective view showing an example of a contact lens using the silicone hydrogel of the present invention. Fig. 3 is a cross-sectional view showing an example of a contact lens using the silicone hydrogel of the present invention. In Fig. 3, 101 is a convex portion, 102 is a concave portion, and 103 is a peripheral portion.

[0106] When used as a contact lens, the thickness of the silicone hydrogel is preferably 0.01 to 4 mm, more preferably 0.01 to 3 mm, even more preferably 0.02 to 2 mm, and particularly preferably 0.03 to 1 mm.

[0107] The contact lens of the present invention can be produced using the method for producing the silicone hydrogel of the present invention.

[0108] Next, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the examples described below. In the following description, "parts" and "%" represent "parts by mass" and "% by mass", respectively.

[0109] [Evaluation Method] (1) Film Thickness The thickness of the silicone hydrogel was measured at three random locations using a 1 / 1000 mm dial gauge, and the average value was taken as the film thickness of the silicone hydrogel.

[0110] (2) Contact Angle Using a contact angle meter ("DropMaster 500" manufactured by Kyowa Interface Science Co., Ltd.), 2 μL of pure water was dropped onto a silicone hydrogel whose surface had been thoroughly wiped clean, and the contact angle was measured after 10 seconds. The measurement was carried out at room temperature (25°C), and the surface of the silicone hydrogel that was in contact with the convex surface of the polypropylene mold during curing was measured.

[0111] (3) Transparency The total light transmittance of the silicone hydrogel was measured using a haze meter NDH-7000II (manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K7136 (2000). The total light transmittance of a silicone hydrogel sample with a film thickness of 0.8 mm was measured, and the transparency was evaluated as follows: A: Total light transmittance of 93% or more B: Total light transmittance of less than 93%

[0112] (4) Atomic Concentration of Each Atom The silicon atom concentration ratio in the thickness direction of the dried body obtained by removing water from the silicone hydrogel was measured by depth profiling using XPS (X-ray photoelectron spectroscopy). Specifically, the silicon atom concentration was determined at each measurement point, starting from the surface of the dried body that was the contact surface of the silicone hydrogel (lens) (the surface on the side of the lens that comes into contact with the eye (the concave surface of the lens)), in the thickness direction of the dried body, starting from the first measurement point (etching time 0, outermost surface of the dried body), the second measurement point (etching time: 50 seconds), and so on, up to the 16th measurement point (etching time: 750 seconds). The silicon concentration distribution indicates the percentage of atoms measured for the elements carbon, oxygen, nitrogen, silicon, and fluorine contained in the dried body, as well as sodium, chlorine, and phosphorus derived from the phosphate buffer solution, with the total number taken as 100 Atom%. The atomic concentration of each atom was determined in the same manner. The measurement conditions were as follows: Measurement equipment: K-Alpha (Thermo Fisher Scientific, Inc.) X-ray monochromatic Al·Kα Spot size: 400 μm Take-off angle (angle between sample surface and detector): 90 degrees Etching conditions: Ionization energy 3000 eV×50 s pitch Ion gun: Ar monoatomic ion

[0113] (5) Water Content Measurement The obtained silicone hydrogel was immersed in a phosphate buffer solution for 3 hours or more, and the surface moisture of the fully swollen gel was wiped off with a Kimwipe or similar, and the weight (W1) was measured at room temperature. The silicone hydrogel was then dried in a dryer set at 90°C for 24 hours, and the weight (W2) was measured again. The water content was calculated according to the following formula: Water content (%) = (W1 - W2) / W1 x 100

[0114] [Surfactants] (C1): Sucrose fatty acid ester ("Ryoto Sugar Ester P-1670" manufactured by Mitsubishi Chemical Corporation, HLB value 16, palmitic acid) (C2): Sucrose fatty acid ester ("Ryoto Sugar Ester S-1570" manufactured by Mitsubishi Chemical Corporation, HLB value 15, stearic acid) (C3): Polyoxyethylene oleyl ether ("Nonion (registered trademark) E-215" manufactured by NOF Corporation, HLB value 14.4)

[0115] [Monomer Mixture] As the silicone (meth)acrylate (A), compound (A1), compound (A2-1), and compound (A2-2) were used alone or in combination. A silicone macromonomer ("MFR-M15" manufactured by Gelest) was used as compound (A1), siloxanyl acrylate ("BX-SiGMMA" (methyldi(trimethylsiloxy)silylpropylglyceryl methacrylate) manufactured by Bimax) was used as compound (A2-1), and 3-[tris(trimethylsilyloxy)silyl]propyl methacrylate (TRIS, "SIM6487.6" manufactured by Gelest) was used as compound (A2-2).

[0116] As the hydrophilic monomer (B), compounds (B1), (B2), and (B3) were used alone or in combination. N,N-dimethylacrylamide (DMA, manufactured by Tokyo Chemical Industry Co., Ltd.) was used as compound (B1), 2-hydroxyethyl methacrylate (HEMA, manufactured by Tokyo Chemical Industry Co., Ltd.) was used as compound (B2), and N-vinyl-2-pyrrolidone (NVP, manufactured by Tokyo Chemical Industry Co., Ltd.) was used as compound (B3).

[0117] Polyethylene glycol (PEG200) dimethacrylate was used as the crosslinking agent (D), and 2,2'-azobis(isobutyronitrile) (AIBN) was used as the polymerization initiator (E). The polymerization initiator (E) was used in an amount of 1 part per 100 parts of the total of the components (A), (B), and (D).

[0118] [Example 1] Surfactant (C1) was used as surfactant (C) and added in the formulation shown in Table 1 to 100 parts in total of components (A), (B), and (D) of the monomer mixture, and polymerization initiator (E) was further added, followed by stirring at room temperature to obtain a curable composition having the formulation shown in Table 1. Surfactant (C1) was mixed uniformly, and a colorless, transparent, liquid curable composition was obtained.

[0119] A general-purpose polypropylene mold was used as a hydrophobic mold for curing the curable composition. The obtained curable composition was poured into the general-purpose polypropylene mold and placed in an oven preheated to 90°C to cure overnight.

[0120] The cured product was then removed from the hydrophobic mold. No solvent was used for removal, and the cured product was removed in a dry state. The removed cured product was then immersed in water to allow it to swell sufficiently, yielding a silicone hydrogel.

[0121] In order to expel the surfactant (C) and other substances contained in the silicone hydrogel, the silicone hydrogel was immersed for 1 hour at 60°C in a solution prepared by mixing 2-propanol and phosphate buffer in a 1:1 ratio in an amount at least 1000 times the dry weight of the silicone hydrogel, and then immersed for 1 hour in phosphate buffer at 60°C, followed by washing.

[0122] The resulting silicone hydrogel was evaluated for film thickness, contact angle, and transparency. The film thickness was 0.13 mm. The evaluation results for contact angle, transparency, and water content are shown in Table 1. The resulting silicone hydrogel was immersed in pure water for 24 hours, then removed from the water and freeze-dried to remove water. The distribution of each element in the depth direction of the dried product was measured using XPS. The results are shown in Table 3. The oxygen atom distribution / silicon atom distribution calculation results are shown in Table 2.

[0123] Examples 2 to 4, Comparative Examples 1 and 2 Silicone hydrogels were obtained in the same manner as in Example 1, except that the components (A), (B), and (D) of the monomer mixture shown in Table 1 were used, and the type and amount of surfactant were changed. The film thickness was 0.13 mm. The results of the contact angle and transparency evaluation are shown in Table 1. In addition, the distribution of each element in the depth direction of the dried body was measured using XPS. The results of Example 2 are shown in Table 4, Example 3 in Table 5, Example 4 in Table 6, Comparative Example 1 in Table 7, and Comparative Example 2 in Table 8. The results of calculating the oxygen atom distribution / silicon atom distribution are shown in Table 2.

[0124]

[0125]

[0126]

[0127]

[0128]

[0129]

[0130]

[0131]

[0132] As shown in Table 1, the silicone hydrogels of Examples 1 to 4 had contact angles after washing that met the standard for a good contact angle of 75° or less, and of these, the contact angles after washing for Examples 1, 2, and 4 met the even better standard for a good contact angle of 60° or less, confirming that high surface hydrophilicity was maintained even after thorough washing with 2-propanol or phosphate buffer. The silicone hydrogels of Examples 1 to 4 also had high total light transmittance and good transparency.

[0133] In contrast, the silicone hydrogels of Comparative Examples 1 and 2 had good transparency, but were found to lack surface hydrophilicity after thorough washing with 2-propanol or phosphate buffer solution.

[0134] When the ratio of oxygen atom concentration to silicon atom concentration at the outermost surface of the dried product was measured by XPS, it was confirmed that Examples 1 to 4 all had a higher ratio of oxygen atom concentration to silicon atom concentration than Comparative Examples 1 and 2, confirming that segregation of silicone to the outermost surface was suppressed. Furthermore, when looking at the A' / B', (A' / B' with surfactant) / (A' / B' without surfactant) ratio in Table 1, the values ​​were higher in Examples 1 to 4 compared to Comparative Example 1, indicating that the addition of one or more specific surfactants (C) suppressed segregation of silicone to the outermost surface. Furthermore, when looking at the water content, it was confirmed that the change in Example 4 was within ±2% compared to Comparative Example 1. These results confirmed that the addition of a surfactant did not significantly change the physical properties of the gel by performing the washing process. From the above, the use of one or more specific surfactants (C) suppressed surface segregation of silicone and reduced the surface contact angle, confirming the usefulness of adding a surfactant before curing.

[0135] REFERENCE SIGNS LIST 10 X-ray photoelectron spectrometer 20 Gas ion beam device 30 Sample stage 100 Sample 200 Contact lens 201 Convex portion 202 Concave portion 203 Peripheral portion

Claims

1. A silicone hydrogel containing water, wherein in a dried body obtained by removing water from the silicone hydrogel, the ratio (A' / B') of the average value (A') of the O / Si concentration ratios from the 1st to 3rd measurement points to the average value (B') of the O / Si concentration ratios from the 14th to 16th measurement points is 1.20 or more. (Here, the O / Si concentration ratio is the ratio of the proportion of oxygen atoms to the proportion of silicon atoms, calculated from the proportion of oxygen atoms (atm %) and the proportion of silicon atoms (atm %) on the surface of the dried body determined by depth profiling using X-ray photoelectron spectroscopy. The O / Si concentration ratio is calculated by determining a total of 16 measurement points every 50 seconds, starting with the first measurement point (etching time 0 seconds, outermost surface of the dried body) and the second measurement point (etching time 50 seconds) when etching the dried body in the thickness direction from the outermost surface by irradiating an Ar ion beam generated under the condition of an ionization energy of 3000 eV, up to the 16th measurement point (etching time 750 seconds), and determining the O / Si concentration ratio at each measurement point.) 2. The silicone hydrogel according to claim 1, further comprising a cured product of a curable composition, the curable composition comprising a silicone-based (meth)acrylate (A), a hydrophilic monomer (B), and a surfactant (C).

3. The silicone hydrogel according to claim 2, wherein the hydrophilic monomer (B) includes a monomer having, in the molecule, one or more types selected from a hydroxyl group, an amino group, a carboxyl group, a (meth)acryloyl group, an ionic group, an amide structure, and an alkyleneoxy structure.

4. The silicone hydrogel according to claim 3, wherein the hydrophilic monomer (B) comprises at least one member selected from the group consisting of N-vinyl-2-pyrrolidone and N,N-dimethylacrylamide.

5. The silicone hydrogel according to claim 2, wherein the surfactant (C) comprises a non-polymerizable surfactant.

6. The silicone hydrogel according to claim 2, wherein the surfactant (C) comprises a sugar-based surfactant.

7. The silicone hydrogel according to claim 6, wherein the sugar-based surfactant comprises a sugar fatty acid ester.

8. The silicone hydrogel according to claim 1, which has a single layer structure in which the difference in O / Si concentration ratio between each of the adjacent measurement points from the first measurement point to the sixteenth measurement point is 10 or less.

9. A contact lens comprising the silicone hydrogel according to any one of claims 1 to 8.

10. A method for producing the silicone hydrogel according to claim 1, comprising the following (1), (2), and (4), and optionally including (3): (1): Preparation of a curable composition comprising a silicone-based (meth)acrylate (A), a hydrophilic monomer (B), and one or more surfactants (C). (2): Molding the curable composition prepared in (1) using a hydrophobic mold to obtain a cured product. (3): Swelling the cured product obtained in (2) with water. (4): Washing the silicone hydrogel obtained in (3).

11. The method of claim 10, wherein the surfactant (C) comprises a non-polymerizable surfactant.

12. The method of claim 10, wherein the surfactant (C) comprises a sugar-based surfactant.

13. The method of claim 12, wherein the sugar-based surfactant comprises a sugar fatty acid ester.

14. The method of claim 10, wherein the hydrophobic mold is a polyolefin mold.

15. The manufacturing method according to claim 10, wherein the silicone hydrogel is not subjected to plasma treatment.

16. A method for producing a contact lens having the silicone hydrogel according to claim 1, comprising producing the silicone hydrogel by the method according to any one of claims 10 to 15.

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