EP-4741445-A1 - SILICONE HYDROGEL, CONTACT LENS, METHOD FOR PRODUCING SILICONE HYDROGEL, AND METHOD FOR PRODUCING CONTACT LENS

Abstract

Provided are a silicone hydrogel that has, even when being produced using a hydrophobic mold such as a polypropylene mold, excellent surface hydrophilicity that is stable for a long period of time without requiring a surface treatment such as a plasma treatment, and a method for producing the same. The silicone hydrogel according to one embodiment of the present invention contains water, and in a dried body produced by removing water from the silicone hydrogel, a ratio (A'/B') of an average value (A') of O/Si concentration ratios at a first measurement point to a third measurement point to an average value (B') of O/Si concentration ratios at a 14th measurement point to a 16th measurement point, which are separately defined, is 1.20 or more.

Inventors

• MISHIMA, SHIORI
• TSURUOKA, Taiki
• TABATA, DAIKI

Assignees

• Mitsubishi Chemical Corporation

Dates

Publication Date

20260513

Application Date

20240704

Claims (16)

1. A silicone hydrogel comprising water, wherein in a dried body produced by removing water from the silicone hydrogel, a ratio (A'/B') of an average value (A') of O/Si concentration ratios at a first measurement point to a third measurement point to an average value (B') of O/Si concentration ratios at a 14th measurement point to a 16th measurement point is 1.20 or more, where each of the O/Si concentration ratios is a ratio of a proportion (atm%) of oxygen atoms to a proportion (atm%) of silicon atoms, the ratio being calculated from the proportion of oxygen atoms and the proportion of silicon atoms, the proportion of oxygen atoms and the proportion of silicon atoms being obtained by depth profiling using X-ray photoelectron spectroscopy at a surface of the dried body, and in etching of the dried body in a thickness direction from an outermost surface of the dried body by irradiation with an Ar ion beam generated under conditions of an ionizing energy of 3000 eV, a total of 16 measurement points are set in such a manner that the first measurement point (etching time: 0 seconds, the outermost surface of the dried body), a second measurement point (etching time: 50 seconds), and so on are sequentially set at every 50 seconds to the 16th measurement point (etching time: 750 seconds), and at each of the total of 16 measurement points, the corresponding O/Si concentration ratio is determined.
2. The silicone hydrogel according to claim 1, further comprising a cured product of a curable composition, wherein the curable composition contains 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) comprises a monomer having, in a molecule, at least one selected from the group consisting of a hydroxy group, an amino group, a carboxy 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 selected from N-vinyl-2-pyrrolidone or 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, wherein the silicone hydrogel has a monolayer structure in which differences in O/Si concentration ratio between adjacent measurement points among the first measurement point to the 16th measurement point are all 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, the method comprising (1), (2), and (4), and optionally (3): (1): preparing a curable composition containing a silicone-based (meth)acrylate (A), a hydrophilic monomer (B), and at least one surfactant (C); (2): molding the curable composition prepared in (1) using a hydrophobic mold to produce a cured product; (3): swelling the cured product produced in (2) using water; (4): washing the silicone hydrogel produced in (3).
11. The production method according to claim 10, wherein the at least one surfactant (C) comprises a non-polymerizable surfactant.
12. The production method according to claim 10, wherein the at least one surfactant (C) comprises a sugar-based surfactant.
13. The production method according to claim 12, wherein the sugar-based surfactant comprises a sugar fatty acid ester.
14. The production method according to claim 10, wherein the hydrophobic mold is a polyolefin mold.
15. The production method according to claim 10, wherein the silicone hydrogel is not subjected to a plasma treatment.
16. A method for producing a contact lens containing the silicone hydrogel described in claim 1, the method comprising producing the silicone hydrogel by the production method according to any one of claims 10 to 15.

Description

Technical Field The present invention relates to a silicone hydrogel, a contact lens, a method for producing a silicone hydrogel, and a method for producing a contact lens. The present application claims priority based on JP 2023-110075 filed in Japan on July 4, 2023 and JP 2024-050042 filed in Japan on March 26, 2024, the contents of which are incorporated herein by reference. Background Art Silicone hydrogels are used as materials for contact lenses, intraocular lenses, and the like because of their high oxygen permeability. In general, soft contact lenses are produced by a cast molding method. In this method, a polypropylene mold is often used. Since polypropylene is hydrophobic, the lens surface tends to be less hydrophilic due to polymerization of the silicone monomer in a state of being oriented on the mold surface. A lens surface that is not sufficiently hydrophilic may be likely to cause adhesion of lipids and proteins thereto, and there is a concern that the lens may become cloudy, or eye diseases may be caused. In addition, such a lens surface may be likely to cause tear break-up, and may consequently cause discomfort such as dryness or friction of the eye, or a disease such as blepharitis. As a technique for improving the surface hydrophilicity of such a contact lens containing a silicone hydrogel, PTL 1 proposes a method of vaporizing a hydrophilic monomer and then generating plasma to form a hydrophilic polymer film on the lens surface. Further, PTL 2 proposes a method of impregnating a contact lens produced after molding with a preservative solution containing a surfactant and a hydrophilic polymer to make the surfactant adhere to the surface of the contact lens. Further, PTL 3 proposes a method of improving hydrophilicity by adding a polymerizable amphiphilic substance and curing the resultant mixture to expose a hydrophilic group on the surface. PTL 4 proposes a method of forming a stable hydrophilic surface of a contact lens by using a monomer that has a specific structure and strongly interacts with some surfactants. Citation List Patent Literature PTL 1: JP S58-216222 APTL 2: JP S61-069023 APTL 3: JP H06-503373 TPTL 4: JP 2014-040598 A Summary of Invention Technical Problem However, unfortunately, the plasma treatment proposed in PTL 1 requires a very large-scale apparatus, and setting of conditions for forming a coating film is complicated. In addition, in the method proposed in PTL 2, the water wettability and surface lubricity of the contact lens cannot be maintained for a long period of time. Moreover, in the method proposed in PTL 3, the amphiphilic substance is copolymerized with other raw materials of the contact lens, affecting the moisture content and mechanical properties of the contact lens. Thus, the contact lens cannot retain suitable physical properties. Furthermore, in the method proposed in PTL 4, the surface hydrophilicity of the contact lens is lowered due to the release of the surfactant by long-term storage, friction during wearing on the eye, or tear replacement. Solution to Problem As a result of intensive studies to solve the above-mentioned issues, the present inventors have found that the above-mentioned problems can be solved, for example, by the following, and have completed the present invention. That is, the present invention has the following aspects. [1] A silicone hydrogel containing water, wherein in a dried body produced by removing water from the silicone hydrogel, a ratio (A'/B') of an average value (A') of O/Si concentration ratios at a first measurement point to a third measurement point to an average value (B') of O/Si concentration ratios at a 14th measurement point to a 16th measurement point is 1.20 or more,whereeach of the O/Si concentration ratios is a ratio of a proportion (atm%) of oxygen atoms to a proportion (atm%) of silicon atoms, the ratio being calculated from the proportion of oxygen atoms and the proportion of silicon atoms, the proportion of oxygen atoms and the proportion of silicon atoms being obtained by depth profiling using X-ray photoelectron spectroscopy at a surface of the dried body, and in etching of the dried body in a thickness direction from an outermost surface of the dried body by irradiation with an Ar ion beam generated under conditions of an ionizing energy of 3000 eV, a total of 16 measurement points are set in such a manner that the first measurement point (etching time: 0 seconds, the outermost surface of the dried body), a second measurement point (etching time: 50 seconds), and so on are sequentially set at every 50 seconds to the 16th measurement point (etching time: 750 seconds), and at each of the total of 16 measurement points, the corresponding O/Si concentration ratio is determined.[2] The silicone hydrogel according to [1], further containing a cured product of a curable composition, wherein the curable composition contains a silicone-based (meth)acrylate (A), a hydrophilic monomer (B), and a surfactant (