Soft ophthalmic lenses and their manufacturing methods

Abstract

This invention provides a method for manufacturing a soft ophthalmic lens. In this method, the surface of the substrate is sufficiently hydrophilicized by performing a single reaction between the substrate and a hydrophilic polymer. Furthermore, this invention provides a soft ophthalmic lens that exhibits sufficient hydrophilicity on the substrate surface by consisting of only a single layer of hydrophilic polymer. By plasma treating a substrate containing a hydrocarbon-containing polysiloxane with an inert gas such as nitrogen, free radicals containing Si-CH₂· are formed on the substrate surface. These free radicals are then transferred to the hydrophilic polymer, and the hydrophilic polymer is bonded to the substrate surface through rebonding of the free radicals generated between the substrate and the hydrophilic polymer.

Description

Technical Field

[0001] This invention relates to a new type of soft ophthalmic lens with a hydrophilic surface and a method for manufacturing the same. Prior Technology

[0002] Currently, soft contact lenses (SCLs) made of polysiloxane (PSA) materials with high oxygen permeability are widely used. High-water-content soft contact lenses (SHGCLs) made of hydrogel materials with a water content of approximately 25% to 80% have been developed, as well as low-water-content or non-water-content contact lenses (FGPCLs) with a water content of less than 10%. Because SHGCLs contain PSA, they have higher oxygen permeability compared to previous SCLs, resulting in a superior wearing comfort. However, due to the higher water content, the dryness caused by water evaporation from the lens can be a problem. In contrast, FGPCLs typically have an even higher PSA content, resulting in even higher oxygen permeability. Being low-water-content or non-water-content, they are expected to reduce the dryness during wear.

[0003] On the other hand, FGPCL lenses have high hydrophobicity / water-repellent properties on their surface, which can cause discomfort when worn, and their low lubricity and stain resistance are also problems.

[0004] For SHGCL or FGPCL with this problem, various techniques for modifying the lens surface have been reviewed. For example, a proposal has been made to hydrophilize the surface of a soft ophthalmic lens by hydrating a substrate obtained by polymerizing polydimethylsiloxane (PDMS) with hydrophilic monomers such as N,N-dimethylacrylamide and ethylene glycol dimethacrylate, and then sequentially immersing it in an aqueous solution of polyvinyl alcohol and a mixed aqueous solution of polyvinylpyrrolidone and polyethylene glycol (PEG) (Patent Document 1).

[0005] In addition, a proposal has been made to introduce ionic chain polymers into a soft lens substrate containing polysiloxane with a network structure, so that the ionic chain polymers are charged and the lens surface is made hydrophilic by adsorbing hydrophilic polymers with opposite charges to them, thus obtaining a soft ophthalmic lens (Patent Document 2).

[0006] In addition, a proposal has been made to impregnate a polysiloxane hydrogel lens substrate obtained by polymerizing a mixture of siloxane-containing monomers or macromonomers and ethylene monomers with N-vinylpyrrolidone in an aqueous solution of anionic polymers with carboxyl groups, such as polyacrylic acid, to adsorb the anionic polymer onto the surface of the substrate, and then crosslink it with water-soluble thermally crosslinking hydrophilic polymers such as polyamide-aminoephidroxol to form a hydrophilic coating, thereby obtaining a silicone hydrogel soft ophthalmic lens (Patent Document 3).

[0007] In addition, soft ophthalmic lenses have been disclosed by using the so-called LbL method to hydrophilize the lens surface by alternating adsorption of acidic and basic polymers onto SHGCL or FGPCL substrates (Patent Documents 4 to 8).

[0008] All these soft ophthalmic lenses adsorb hydrophilic polymers onto a substrate via non-covalent bonding. Consequently, the coating composed of hydrophilic polymers is easily detached from the lens surface due to physical stimuli such as scrubbing. Furthermore, in the case of these soft ophthalmic lenses, adsorbing the hydrophilic polymer onto the substrate surface only once results in insufficient amounts of hydrophilic polymers present on the substrate surface, leaving some exposed. Therefore, a second hydrophilic polymer is adsorbed or bonded to the first hydrophilic polymer as a base. This complicates the manufacturing process and increases manufacturing costs.

[0009] In contrast, soft ophthalmic lenses have also been developed by using various methods to covalently bond hydrophilic polymers to a substrate to form a hydrophilic coating.

[0010] For example, there is a method for forming a hydrophilic coating on a substrate by plasma polymerization in a gaseous environment containing a coating material. Specifically, a method has been proposed in which a lens substrate made of polydimethylsiloxane (PDMS) is placed in a glow discharge polymerization apparatus, and a mixed gas of hydrocarbons such as methane and halogenated hydrocarbons such as perfluoromethane is introduced after depressurization. Plasma is generated by glow discharge, and a coating with a graphite-like tightly cross-linked structure is formed on the substrate (Patent Document 9). In addition, this document has proposed a method for forming a hydrophilic coating by placing a lens substrate made of PDMS in a glow discharge polymerization apparatus, introducing a mixed gas of hydrogen and halogenated hydrocarbons such as tetrafluoroethylene after depressurization, generating plasma by glow discharge, and further introducing oxygen into the environment to generate oxygen plasma by glow discharge.

[0011] In addition, a method has been proposed to place a lens substrate containing polysiloxane in a mixture of coating materials such as alkanes and N-vinylpyrrolidone with inert gases such as air, oxygen or argon, and form a hydrophilic coating by plasma polymerization (Patent Document 10).

[0012] In these methods of forming coatings via plasma polymerization, the coating material is exposed to plasma to form free radicals, which then react with the substrate surface, resulting in a coating with properties different from the original hydrophilic polymer. For example, when using N-vinylpyrrolidone for plasma polymerization, various types of free radicals are generated, all of which participate in the polymerization reaction to form a complex cross-linked structure (Non-Patent Document 1). Furthermore, decomposition products of N-vinylpyrrolidone are also generated in the gas phase. Therefore, the coating formed by plasma polymerization is completely different from polyvinylpyrrolidone; it is a substance similar to amorphous carbon. Thus, there is a need for a technology to form coatings with the properties of the original hydrophilic polymer.

[0013] To address this need, a method has been disclosed for activating a lens substrate using plasma treatment, thereby reacting the activated surface with a hydrophilic polymer containing functional groups to form a coating. For example, it has been proposed to perform plasma treatment on a substrate in air, oxygen, methane, CO2, a mixture of oxygen and methane, a mixture of CO2 and methane, or a mixture of methane and air. After treatment, a base coating is formed by immersing the substrate in an acidic solution of an anionic polymer with carboxyl groups or an alkaline solution of a cationic polymer with primary / secondary amine groups. A hydrogel coating is then formed on an SHGCL substrate or an FGPCL substrate by crosslinking the substrate with a hydrophilic polymer having predetermined reactive groups (Patent Documents 11 and 12).

[0014] In addition, a method has been proposed to treat an FGPCL substrate based on polysiloxane with oxygen plasma to generate silanol groups (Si-OH) on the surface, and to perform a silane coupling reaction on a hydrophilic polymer with silane coupling groups at the ends to form a hydrophilic layer on the substrate surface (Patent Document 13).

[0015] Furthermore, a method has been disclosed in which a first polymer species having predetermined reactive groups is covalently bonded to the surface of an FGPCL substrate containing 75% or more polysiloxane, and then a second polymer species having predetermined reactive groups is crosslinked with the first polymer species to form a hydrogel layer. As one of the various means of covalently bonding the first polymer species to the substrate, plasma treatment can be cited (Patent Documents 14 and 15). However, these documents do not describe specific manufacturing examples using plasma treatment, nor do they show the specific conditions for covalently bonding the first polymer species to the substrate using plasma treatment. [Previous Technical Documents] [Patent Literature]

[0016] [Patent Document 1] Japanese Patent Application Publication No. 2020-42253 [Patent Document 2] Japanese Patent No. 6230880 [Patent Document 3] U.S. Patent Application Publication No. 2017 / 0165932 [Patent Document 4] Japanese Patent No. 4551219 [Patent Document 5] Japanese Patent No. 5064498 [Patent Document 6] Japanese Patent No. 4634603 [Patent Document 7] Japanese Patent Application Publication No. 2016-28292 [Patent Document 8] Japanese Patent Application Publication No. 2020-8873 [Patent Document 9] US Patent No. 4,312,575 [Patent Document 10] European Patent Application Publication No. 1043605 [Patent Document 11] Japanese Patent No. 6592189 [Patent Document 12] Japanese Patent No. 6680870 [Patent Document 13] Japanese Patent Application Publication No. 2015-158615 [Patent Document 14] Japanese Patent Application Publication No. 2017-530423 [Patent Document 15] Japanese Patent Application Publication No. 2019-219666 [Patent Document 16] International Publication No. 2017 / 175705 [Non-patent literature]

[0017] [Non-patent literature 1] C. Dispenza, et. al., Radiation Physics and Chemistry, 2020, Vol.174, 108900. [Non-Patent Literature 2] J. Wu, et. al., Lab Chip, 2014, 14, 1564-1571. [Non-patent literature 3] SRA Kratz, et al., Scientific Reports, 2020, 10:1400. [Non-Patent Literature 4] E. Ismail, et al., Chemistry Letters, 2020, CL-200504. [Non-Patent Literature 5] P. Zhang, et. al., Phys. Chem. Chem. Phys., 2014, Vol.16, 17479-17486. [Non-Patent Literature 6] I. Auzmendi-Murua, et. al., Journal of Physical Chemistry A, 2014, Vol.118, 3147-3167. Summary of the Invention

[0018] [The problem that the invention aims to solve]

[0019] Accordingly, in the case of soft ophthalmic lenses that have previously formed hydrophilic coatings by plasma treatment, plasmas containing air, oxygen, methane, CO2, etc., are used to partially decompose polysiloxane (or polysiloxane compounds) such as PDMS to produce hydroxyl groups or hydrocarbons containing hydroxyl groups. Covalent bonds (such as ester bonds, amide bonds, and siloxane bonds) are formed between these groups and the functional groups (such as carboxyl groups, amino groups, and silane coupling groups) of hydrophilic polymers. However, in this conventional method, the substrate surface obtained by covalently bonding the first hydrophilic polymer to the substrate surface through plasma treatment is not sufficiently hydrophilic. Further hydrophilication of the substrate surface is achieved by adsorbing or cross-linking the second hydrophilic polymer to the first hydrophilic polymer. Therefore, a plasma treatment-based manufacturing method with a simpler process and reduced manufacturing costs is being sought. The present invention addresses this need, and more specifically, provides a method for manufacturing a soft ophthalmic lens. In this method, the surface of the substrate is sufficiently hydrophilicized by performing a single reaction between the substrate and a hydrophilic polymer. Furthermore, another objective of the present invention is to provide a soft ophthalmic lens that possesses sufficient hydrophilicity on the substrate surface consisting of only a single layer composed of a hydrophilic polymer. [Methods for solving problems]

[0020] The aforementioned issue, namely, in order to provide sufficient hydrophilicity to a polysiloxane-containing lens with a layer composed of hydrophilic polymers, the inventors first clarified the mechanism by which hydrophilic polymers are bonded to the substrate via plasma treatment. In conventional methods for bonding hydrophilic polymers to a substrate using air or oxygen plasma treatment, Si-OH groups are formed on the substrate surface by reactive oxygen generated during plasma treatment, and then react with the functional groups of the hydrophilic polymer. However, these Si-OH groups react strongly with the Si-OH groups of other polysiloxanes to form Si-O-Si bonds, and the Si-OH groups on the substrate surface decrease over time after plasma treatment (Non-Patent Documents 2 and 3). Furthermore, the functional groups (carboxyl and amine groups) of the hydrophilic polymer do not react with the Si-OH groups of polysiloxanes under neutral conditions, as described in Patent Document 12, but must react with or adsorb onto the Si-OH groups on the substrate surface under acidic or alkaline conditions. Therefore, it has been confirmed that conventional methods for bonding hydrophilic polymers to a substrate using air or oxygen plasma treatment, or simply forming a base coating, are insufficient to impart adequate hydrophilicity.

[0021] On the other hand, in plasma treatment using gases such as methane or CO2 that are mixed with air or oxygen, reactive groups such as Si-CH2-OH introduced from carbon atoms can be generated on the PDMS surface. These reactive groups are more stable than Si-OH. However, this plasma treatment, in its ability to generate OH groups on the substrate surface and react them with the functional groups of hydrophilic polymers, is similar; it is difficult to impart sufficient hydrophilicity solely through this reaction. Furthermore, to generate this reaction, plasma treatment is performed using a (mixed) gas containing oxygen. However, gases containing oxygen or carbon such as methane or CO2 will generate corresponding active species during plasma treatment. These react with free radicals on the substrate surface to form stable chemical bonds, making the use of free radicals generated on the substrate surface unsuitable. For example, the Si· free radical forms a stable Si-O bond with activated oxygen atoms, and the Si-CH2· free radical forms Si-CH2-C with activated carbon atoms. Therefore, the gases conventionally used for plasma treatment reduce the free radicals generated on the substrate surface.

[0022] Based on the bonding mechanism and problems of conventional plasma treatment, the inventors focused on a reaction system that utilizes free radicals generated on the substrate surface to react with hydrophilic polymers, and examined various plasma treatment conditions. As a result, they discovered that when a substrate containing an alkyl-containing polysiloxane structure is plasma-treated with an inert gas such as nitrogen, free radicals containing Si-CnH2n· are formed on the substrate surface. These free radicals transfer to the hydrophilic polymer, and through the free radicals generated by the hydrophilic polymer, the hydrophilic polymer can be efficiently bonded to the substrate surface. The resulting coating was confirmed to be uniform and achieve sufficient hydrophilicity, thus completing this invention.

[0023] That is, the present invention provides a method for manufacturing a soft ophthalmic lens and a soft ophthalmic lens.

[0024] [1] A soft ophthalmic lens comprising Ophthalmic lens substrate comprising an alkyl-containing polysiloxane structure (co)polymer, and The surface of this substrate contains a single coating of hydrophilic polymer. The water contact angle of the aforementioned coating surface is less than 70°. [2] The soft ophthalmic lens described in [1] has a full width at half maximum (FWHM) of less than 2.1 eV as measured by XPS for the entire peak originating from Si 2p. [3] As described in [1], in the soft ophthalmic lens, more than 60% of the peak originating from Si 2p as measured by XPS is bonded to 2 O atoms and 2 C atoms. [4] The soft ophthalmic lens described in any of [1] to [3], wherein adsorbed water was confirmed on the surface of the coating by XPS analysis at a water vapor pressure of 5 mbar. [5] The soft ophthalmic lens described in any of [1] to [4], wherein the water contact angle of the aforementioned coating surface is less than 60° or 50°.

[0025] [6] The soft ophthalmic lens described in any of [1] to [5], wherein the water contact angle of the aforementioned coating surface is less than 70° after 20 rubbing tests.

[0026] [7] As described in [6], the soft ophthalmic lens has a water contact angle of less than 60° after 20 rubbing tests on the aforementioned coated surface. [8] The soft ophthalmic lens described in any of [1] to [5], wherein the water contact angle of the aforementioned coating surface is less than 50° after 200 rubbing tests.

[0027] [9] The soft ophthalmic lens described in any of [1] to [8], wherein the aforementioned coating has a thickness of 1 nm to 5 μm.

[0028]

[10] The soft ophthalmic lens described in any of [1] to [9], wherein the aforementioned substrate and the aforementioned hydrophilic polymer are bonded at least via a C-C bond between the Si-C of the substrate and the C of the hydrophilic polymer.

[11] The soft ophthalmic lens described in any of [1] to

[10] , wherein the aforementioned substrate and the hydrophilic polymer are further bonded via an OC bond between the Si-alkyl-OO of the substrate and the C of the aforementioned hydrophilic polymer.

[0029]

[12] As described in

[10] or

[11] , the aforementioned substrate and the hydrophilic polymer are further bonded via Si-C bonds between the Si of the aforementioned substrate and the C of the hydrophilic polymer.

[0030]

[13] The soft ophthalmic lens described in any of

[10] to

[12] , wherein more than 5% of the alkyl-containing polysiloxane units present on the surface of the aforementioned substrate are bonded to the C of the aforementioned hydrophilic polymer.

[0031]

[14] The soft ophthalmic lens as described in

[12] or

[13] , wherein more than 10% of the alkyl-containing polysiloxane units present on the surface of the aforementioned substrate are bonded to the C of the aforementioned hydrophilic polymer.

[0032]

[15] The soft ophthalmic lens described in any of [1] to

[14] , wherein the aforementioned hydrophilic polymer is water-soluble and has atoms or double bonds with non-covalent bond pairs, and the carbon system adjacent to the atoms or double bonds with non-covalent bond pairs is bonded to the carbon of Si, Si-C or oxygen of Si-alkyl-OO of the aforementioned substrate.

[0033]

[16] The soft ophthalmic lens described in any of [1] to

[15] , wherein the aforementioned substrate is obtained by polymerizing a (macromolecule) monomer composition containing 20% ​​by mass or more of an alkyl-containing polysiloxane.

[0034]

[17] The soft ophthalmic lens described in

[16] is obtained by polymerizing a (macromolecule) monomer composition containing more than 30% by mass of alkyl-containing polysiloxane.

[0035]

[18] The soft ophthalmic lens described in any of [1] to

[17] is wherein the aforementioned (co)polymer having an alkyl-containing polysiloxane structure is obtained by polymerizing a (macro)monomer containing an alkylsiloxane having two or more polymerizable reactive groups.

[0036]

[19] As described in

[18] , the soft ophthalmic lens, wherein the aforementioned substrate is obtained by polymerizing an alkylsiloxane having two or more polymerizable reactive groups and a (macromolecule) monomer composition arbitrarily selected from at least one of alkylsiloxane having one polymerizable reactive group, (meth)fluoroalkyl acrylate, (meth)alkyl acrylate and (meth)dialkylaminoalkyl acrylate.

[0037]

[20] The soft ophthalmic lens described in

[19] contains, in the aforementioned (macromolecule) monomer composition, 20 to 50% by mass of the aforementioned alkylsiloxane having two or more polymerizable reactive groups and the aforementioned alkylsiloxane having one polymerizable reactive group, and 30 to 65% by mass of the aforementioned (meth)acrylate fluoroalkyl ester.

[0038]

[21] The soft ophthalmic lens described in any of

[18] to

[20] , wherein the aforementioned polymeric reactive group is a (meth)acrylate group.

[0039]

[22] The soft ophthalmic lens described in any of [1] to

[21] , wherein the polysiloxane unit of the aforementioned (co)polymer present on the surface of the aforementioned substrate has SiOH, Si-CH2-OH or OC=O bonded to Si.

[23] As described in any one of [1] to

[22] , the soft ophthalmic lens, wherein the aforementioned hydrophilic polymer comprises at least one selected from the group consisting of: polyvinylpyrrolidone (PVP), polyacrylamide, compounds in which the nitrogen atom of polyacrylamide is alkyl-substituted (e.g., poly(N,N-diethylacrylamide), poly(N,N-dimethylacrylamide), poly(N-isopropylacrylamide) etc.), poly(N-vinylacetamide), poly(N-vinylformaldehyde), poly(N-vinylisobutyrate), polyacrylamide epichlorohydrin, poly(2- (azoline), poly(2-ethyl-2-) (e.g., oxazoline), polyacrylic acid, compounds having hydrophilic groups (e.g., hydroxyethyl) on the oxygen atom of polyacrylic acid (e.g., HEMA), polymethacrylic acid, polylysine, polymaleic acid, alginate, chondroitin sulfate, pectin, hyaluronic acid, chitosan, polysialic acid, pullulan, dextran, cellulose, polyethylene glycol (PEG), block copolymers containing PEG (e.g., block copolymers of PEG and polyacrylic acid, block copolymers of PEG and polyamino acids such as polylactic acid), surfactants containing PEG (PEG with a long-chain alkyl group at one end), polymers with PEG-terminated ends (e.g., PEG with methyl, ethyl, benzyl, dibenzylpropyl, dimethylaminoethyl, etc. at the end), polyphosphatidylcholine, polytetrahydrofuran, polyvinyl alcohol, polymethyl vinyl ether, polyethyleneimine (PEI), polyallylamine, polydiallylamine, polymethyldiallylamine, poly(N-vinylamine), poly(vinyl-N-methylpyridinium salt), polyvinylphosphonic acid, polyvinylsulfonic acid, polystyrene sulfonic acid, polystyrene sulfonate, poly(3-sulfopropyl potassium methacrylate), hydroxyethyl cellulose, hydroxypropyl methylcellulose, polydimethyldiallyl ammonium salt, poly(vinyl methacrylate), poly(2-vinylpyridine-N-oxide), and copolymers obtained by crosslinking two or more of these hydrophilic polymers (e.g., ethylene glycol crosslinked polymers of polyacrylic acid (e.g., CLPAH-100)) and (co)polymers having such hydrophilic polymers as branched structures and being hydrophilic (e.g., PEG derivatives obtained by bonding at least one of these hydrophilic polymers as branched structures to PEG).

[0040]

[24] As described in

[23] , the aforementioned hydrophilic polymers include polyvinylpyrrolidone, polyacrylic acid, ethylene glycol crosslinked polyacrylic acid, polyacrylic acid starch grafts, PEG, block copolymers containing PEG, alginate, chondroitin sulfate, hyaluronic acid, pectin, hydroxyethyl cellulose, dextran, polyvinyl alcohol, polyethyleneimine, polyglutamic acid, or polyacrylamide.

[0041]

[25] As described in

[24] , the soft ophthalmic lens contains the aforementioned hydrophilic polymers including polyvinylpyrrolidone, ethylene glycol crosslinked polymers of polyacrylic acid, polyacrylic acid, chondroitin sulfate, hydroxyethyl cellulose, polyvinyl alcohol, block copolymers containing PEG, or PEG.

[0042]

[26] The soft ophthalmic lens described in any of [1] to

[25] has an oxygen permeability (Dk value) of 150 or higher.

[27] A method for manufacturing a soft ophthalmic lens, comprising: The step of subjecting an ophthalmic lens substrate comprising a (co)polymer having an alkyl-containing polysiloxane structure to plasma treatment in an inert gas environment to form free radicals on the surface of the substrate, and The step of immersing the substrate in an aqueous solution containing a hydrophilic polymer with a structure capable of resonating with free radicals on carbon atoms to form a coating containing the hydrophilic polymer.

[0043]

[28] The method described in

[27] , wherein the aforementioned free radicals include Si· free radicals and Si-alkyl· free radicals.

[0044]

[29] The method described in

[28] further comprises Si-enylalkyl-OO· radical.

[0045]

[30] The method described in any of

[27] to

[29] , wherein, immediately after the plasma treatment, at least 10% of the C in the Si bonds present on the surface of the substrate becomes free radicals.

[0046]

[31] In the method described in

[30] , immediately after the plasma treatment, at least 15% of the Si present on the surface of the substrate and the C bonded to the Si become free radicals.

[32] The method described in any of

[27] to

[31] , wherein, immediately after the plasma treatment, at least 20% of the alkyl-containing polysiloxane units present on the surface of the substrate become free radicals.

[33] The method described in any of

[27] to

[32] , wherein the aforementioned plasma is generated at a low frequency of 50 Hz or 60 kHz and a power of 10 to 150 W.

[0047]

[34] The method described in

[33] is wherein the aforementioned inert gas is introduced into the reaction chamber at a pressure of 2 Pa to 30 Pa and a speed of 1 sccm to 100 sccm.

[0048]

[35] The method described in

[33] or

[34] , wherein the aforementioned plasma treatment is performed for 5 seconds to 2 minutes.

[36] The method described in

[35] wherein the aforementioned plasma is generated at a power of 60 to 150 W and the aforementioned plasma treatment is performed for 50 seconds to 2 minutes.

[0049]

[37] The method described in any of

[27] to

[32] , wherein the aforementioned plasma is generated at 3 to 30 mA by glow discharge.

[38] The method described in any of

[27] to

[37] , wherein the aforementioned inert gas is N2 gas or Ar gas.

[0050]

[39] The method described in any of

[27] to

[38] , wherein the aforementioned substrate is obtained by polymerizing a (macromolecule) monomer composition comprising 20% ​​by mass or more of an alkyl-containing polysiloxane.

[0051]

[40] The method described in

[39] is wherein the aforementioned substrate is obtained by polymerizing a (macromolecule) monomer composition comprising 30% by mass or more of an alkyl-containing polysiloxane.

[0052]

[41] The method described in any one of

[27] to

[40] , wherein the aforementioned (co)polymer having an alkyl-containing polysiloxane structure is obtained by polymerizing a (macro)monomer containing an alkylsiloxane having two or more polymerizable reactive groups.

[0053]

[42] The method described in

[41] wherein the aforementioned substrate is obtained by polymerizing an alkylsiloxane having two or more polymerizable reactive groups and a (macromolecule) monomer composition arbitrarily selected from at least one of an alkylsiloxane having one polymerizable reactive group, a fluoroalkyl (meth)acrylate, an alkyl (meth)acrylate and a dialkylaminoalkyl (meth)acrylate.

[0054]

[43] The method described in

[42] , wherein the aforementioned (macromolecule) monomer composition contains 20 to 50% by mass of the aforementioned alkylsiloxane having two or more polymerizable reactive groups and the aforementioned alkylsiloxane having one polymerizable reactive group, and contains 30 to 65% by mass of the aforementioned (meth)acrylate fluoroalkyl ester.

[0055]

[44] The method described in any of

[41] to

[43] , wherein the aforementioned polymerizable reactive group is a (meth)acrylate group.

[0056]

[45] The method described in any of

[27] to

[44] , wherein the aforementioned hydrophilic polymer is water-soluble, has alkyl and / or alkylene and / or methine, and atoms or double bonds with non-shared electron pairs, wherein the carbon system of the aforementioned alkyl or alkylene or methine exists adjacent to the aforementioned atoms or double bonds with non-shared electron pairs.

[0057]

[46] The method described in any one of

[27] to

[45] , wherein the aforementioned hydrophilic polymer comprises at least one selected from the group consisting of: polyvinylpyrrolidone (PVP), polyacrylamide, compounds in which the nitrogen atom of polyacrylamide is alkyl-substituted (e.g., poly(N,N-diethylacrylamide), poly(N,N-dimethylacrylamide), poly(N-isopropylacrylamide) etc.), poly(N-vinylacetamide), poly(N-vinylformaldehyde), poly(N-vinylisobutyrate amide), polyacrylamide epichlorohydrin, poly(2- (azoline), poly(2-ethyl-2-) (e.g., oxazoline), polyacrylic acid, compounds having hydrophilic groups (e.g., hydroxyethyl) on the oxygen atom of polyacrylic acid (e.g., HEMA), polymethacrylic acid, polylysine, polymaleic acid, alginate, chondroitin sulfate, pectin, hyaluronic acid, chitosan, polysialic acid, pullulan, dextran, cellulose, polyethylene glycol (PEG), block copolymers containing PEG (e.g., block copolymers of PEG and polyacrylic acid, block copolymers of PEG and polyamino acids such as polylactic acid), surfactants containing PEG (PEG with a long-chain alkyl group at one end), polymers with PEG-terminated ends (e.g., PEG with methyl, ethyl, benzyl, dibenzylpropyl, dimethylaminoethyl, etc. at the end), polyphosphatidylcholine, polytetrahydrofuran, polyvinyl alcohol, polymethyl vinyl ether, polyethyleneimine (PEI), polyallylamine, polydiallylamine, polymethyldiallylamine, poly(N-vinylamine), poly(vinyl-N-methylpyridinium salt), polyvinylphosphonic acid, polyvinylsulfonic acid, polystyrene sulfonic acid, polystyrene sulfonate, poly(3-sulfopropyl potassium methacrylate), hydroxyethyl cellulose, hydroxypropyl methylcellulose, polydimethyldiallyl ammonium salt, poly(vinyl methacrylate), poly(2-vinylpyridine-N-oxide), and copolymers obtained by crosslinking two or more of these hydrophilic polymers (e.g., ethylene glycol crosslinked polymers of polyacrylic acid (e.g., CLPAH-100)) and (co)polymers having such hydrophilic polymers as branched structures and being hydrophilic (e.g., PEG derivatives obtained by bonding at least one of these hydrophilic polymers as branched structures to PEG).

[0058]

[47] The method described in

[46] , wherein the aforementioned hydrophilic polymer includes polyvinylpyrrolidone, polyacrylic acid, ethylene glycol crosslinked polyacrylic acid, polyacrylic acid starch graft, PEG, block copolymer containing PEG, alginate, chondroitin sulfate, hyaluronic acid, pectin, hydroxyethyl cellulose, dextran, polyvinyl alcohol, polyethyleneimine, polyglutamic acid or polyacrylamide.

[48] ​​The method described in

[47] , wherein the aforementioned hydrophilic polymer includes polyvinylpyrrolidone, ethylene glycol crosslinked polymer of polyacrylic acid, polyacrylic acid, chondroitin sulfate, hydroxyethyl cellulose, polyvinyl alcohol, block copolymer containing PEG or PEG.

[0059]

[49] The method described in any of

[27] to

[48] , wherein the substrate subjected to the aforementioned plasma treatment is kept in an oxygen-containing environment for a short time (preferably within 10 seconds).

[0060]

[50] The method described in

[49] , wherein the oxygen concentration of the aforementioned oxygen-containing environment is 0.5 to 20 by mass.

[0061]

[51] The method described in

[50] , wherein the oxygen concentration of the aforementioned oxygen-containing environment is 0.8 to 10 by mass.

[0062]

[52] The method described in any of

[27] to

[51] , wherein the substrate having formed the aforementioned free radical is immersed in the aforementioned aqueous solution of the hydrophilic polymer within 10 seconds after the aforementioned plasma treatment.

[0063]

[53] The method described in any of

[27] to

[52] , wherein the substrate having formed the aforementioned free radical is immersed in an aqueous solution of the aforementioned hydrophilic polymer at a temperature of 5 to 135°C for 20 minutes to 2 hours.

[54] As described in

[53] , the substrate having formed the aforementioned free radical is immersed in the aforementioned aqueous solution of the hydrophilic polymer at a temperature of 10 to 30°C for 30 minutes to 1 hour, and then heated at a temperature of 80 to 135°C for 20 minutes to 2 hours.

[0064]

[55] The method described in any of

[27] to

[54] , wherein the concentration of the aforementioned hydrophilic polymer in the aqueous solution is 0.01% to 1% by mass.

[56] The method described in any of

[27] to

[55] , wherein, after the aforementioned impregnation, the water or buffer solution is heated.

[57] The method described in

[56] involves performing the aforementioned heat treatment for 20 minutes to 2 hours in a lens preservation solution at a temperature of 80 to 135°C.

[0065]

[58] The method described in any of

[27] to

[57] , wherein the aforementioned coating has a thickness of 1 nm to 5 μm.

[0066]

[59] A soft ophthalmic lens, which is manufactured by the method described in any of

[27] to

[58] .

[0067] As described above, in this invention, the substrate surface is activated by plasma treatment of a (co)polymer containing a hydrocarbon group, preferably an alkyl group, in an inert gas environment without the use of a gas containing carbon or oxygen atoms. When activated by plasma, the compound containing the alkyl polysiloxane structure generates Si· radicals or Si-CnH2n· radicals (typically Si-CH2· radicals). However, when the plasma is formed using a gas containing oxygen or carbon, the active species of oxygen or carbon form stable chemical bonds with the radicals on the substrate surface. That is, Si· radicals form stable Si-O bonds with oxygen, and Si-CnH2n· radicals form Si-CnH2n-C bonds with carbon, thus reducing the number of radicals on the substrate surface. In contrast, when plasma treatment is performed on (co)polymers with alkyl-containing polysiloxane structures in an inert gas environment, the inert gas does not react with free radicals, resulting in a higher concentration of Si· or Si-CnH2n· free radicals on the substrate surface. If this substrate is immersed in an aqueous solution of a hydrophilic polymer, the free radicals on the substrate surface, specifically the Si-CnH2n· free radicals, will undergo free radical transfer to the hydrophilic polymer, generating free radicals within the polymer. As a result, a rebonding of free radicals occurs between the substrate and the hydrophilic polymer, thereby establishing a bond between the substrate and the hydrophilic polymer. In cases where plasma treatment is performed using gases containing oxygen or carbon, the bonding frequency between the substrate and the hydrophilic polymer is low, thus failing to achieve sufficient hydrophilization. However, in the method of the present invention, which utilizes a large number of free radicals generated by the substrate and the hydrophilic polymer to bond the two, the bonding frequency between the substrate and the hydrophilic polymer is high, and sufficient hydrophilization can be achieved through a single plasma treatment. Simple Explanation of the Diagram

[0068] [Figure 1] Figure 1 is a conceptual diagram schematically showing the structure near the surface of a lens according to an embodiment of the present invention. [Figure 2] shows the spectrum of the O 1S region obtained by XPS analysis of the sample from Example 1. [Figure 3] shows the spectrum of the C1S region obtained by XPS analysis of the sample from Example 1. [Figure 4] shows the spectrum of the C1S region obtained by XPS analysis of the sample from Example 2. [Figure 5] shows the spectrum of the Si 2p region obtained by XPS analysis of the sample of Synthesis Example 1. [Figure 6] shows the spectrum of the Si 2p region obtained by XPS analysis after plasma treatment of the sample of Synthesis Example 1. [Figure 7] shows the spectrum of the Si 2p region obtained by XPS analysis of the sample from Example 1. [Figure 8] shows the spectrum of the Si 2p region obtained by XPS analysis of the sample of Reference Example 1. [Figure 9] shows the spectrum of the O 1S region obtained by XPS analysis of the sample from Example 3. [Figure 10] shows the spectrum of the C 1s region obtained by XPS analysis of the plasma-treated substrate in Example 3. [Figure 11] shows the spectrum of the C 1s region obtained by XPS analysis of the sample from Example 3. Implementation

[0069] The embodiments of the present invention will be described in detail. However, the present invention should not be construed as being limited to the following embodiments. Furthermore, in this specification, the term "(macromolecular) monomer" means macromolecular monomer and / or monomer. Additionally, in this specification, the term "(meth)acrylyl" means methacryl and / or acrylyl, and the terms (meth)acrylyl, (meth)acrylate, etc., are used with the same grammar. Similarly, the term "(co)polymer" means copolymer or polymer. In this specification, "Si-alkyl radical" is synonymous with "Si-CnH2n radical" and is sometimes abbreviated as "Si-C radical". Similarly, in this specification, "Si-alkyl-OO radical" is synonymous with "Si-CnH2n-OO radical" and is sometimes abbreviated as "Si-COO radical".

[0070] The manufacturing method of the soft ophthalmic lens of the present invention includes: subjecting an ophthalmic lens substrate containing a polymer capable of forming free radicals by plasma to plasma treatment in an inert gas environment, thereby forming free radicals on the surface of the substrate; immersing the substrate with formed free radicals in an aqueous solution of a hydrophilic polymer, thereby generating free radical transfer to the hydrophilic polymer and forming a hydrophilic polymer coating. The soft ophthalmic lens of the present invention is a lens obtained by this method, wherein the surface of the substrate contains a coating containing a hydrophilic polymer, and a single coating exhibits high hydrophilicity. The following is a detailed description.

[0071] 1. Substrate The substrate used in the ophthalmic soft lens of the present invention comprises a polymer capable of forming silicon or carbon free radicals by plasma of an inert gas. Such polymer is generally composed of silicon, oxygen, carbon and hydrogen, preferably a (co)polymer having an alkyl-containing polysiloxane structure, and more preferably a (co)polymer having structural units as shown in formula (1). (In formula (1), R1 and R2 independently represent alkyl or hydrogen atoms. Each structural unit may be different, or some or all of the structural units may be the same. However, at least one R1 or R2 is a hydrocarbon group. N represents an integer greater than 2.)

[0072] As an alkyl group, in order to reduce the water repellency and hydrophobicity of the substrate itself, it is preferred to be an alkyl group with 10 or fewer carbon atoms, more preferably an alkyl group with 1 to 5 carbon atoms, and even more preferably an alkyl group with 1 to 3 carbon atoms. On the other hand, in order to form more free radicals on the substrate by plasma treatment, it is preferable that at least one of R1 and R2 in each siloxane unit shown in formula (1) is an alkyl group. Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, tributyl, decyl, etc., with methyl, ethyl, propyl and isopropyl being more preferred, methyl and ethyl being even more preferred, and methyl being the most preferred.

[0073] n represents the number of structural units shown in equation (1), which is usually in the range of 2 to 1500, preferably 80 or more, and even more preferably 100 or more. Specifically, it is preferably 100 to 1400, even more preferably 120 to 950, and even more preferably 130 to 700.

[0074] The aforementioned (co)polymers having an alkyl-containing polysiloxane structure are typically obtained by polymerizing a polysiloxane compound having a plurality of polymerizable functional groups and one or more alkyl groups per molecule (hereinafter referred to as component A), or component A and other polymerizable compounds (hereinafter referred to as component B).

[0075] The polymerizable functional group of component A is preferably a functional group capable of free radical polymerization, and more preferably a group having a carbon-carbon double bond. Examples of preferred polymerizable functional groups include vinyl, allyl, (meth)acrylyl, α-alkoxymethacrylyl, maleic acid residue, fumaric acid residue, itconic acid residue, crotonic acid residue, isocrotonic acid residue, and citrate residue. Among these, (meth)acrylyl is particularly preferred due to its high polymerizability.

[0076] The alkyl group of component A may be listed as the same alkyl group as the alkyl group of the structural unit shown in formula (1), and preferably the same alkyl group.

[0077] The weight-average molecular weight of component A is preferably 6,000 or higher, more preferably in the range of 9,000 to 160,000, and even more preferably in the range of 10,000 to 70,000. Furthermore, the dispersibility of component A (the value obtained by dividing the weight-average molecular weight by the number-average molecular weight) is preferably 6 or lower, more preferably 3 or lower, even more preferably 2 or lower, and particularly preferably 1.5 or lower. In this specification, the number-average molecular weight, weight-average molecular weight, and dispersibility of component A are the number-average molecular weights converted from polystyrene determined by gel permeation chromatography (GPC) using chloroform as the solvent.

[0078] As component B, examples include polysiloxane compounds (hereinafter referred to as component B1) having (usually at one end) one or more hydrocarbon groups and one polymerizable functional group per molecule, hydrophobic (meth)acrylates (hereinafter referred to as component B2) having one or more polymerizable functional groups but not having a siloxane structure, hydrophilic (meth)acrylates (hereinafter referred to as component B3) having one or more polymerizable functional groups but not having a siloxane structure, and other monomers (hereinafter referred to as component B4).

[0079] The polymerizable functional group system of component B1 is the same as that of component A. Preferred polymerizable functional groups include vinyl, allyl, (meth)acryl, α-alkoxymethacryl, maleic acid residue, fumaric acid residue, itaconic acid residue, crotonic acid residue, isocrotonic acid residue and citrate residue, with (meth)acryl being particularly preferred.

[0080] The alkyl group of component B1 is the same as that of component A, and can be listed as the same alkyl group as the alkyl group of the structural unit shown in formula (1), preferably the same alkyl group.

[0081] The weight average molecular weight of component B1 is preferably 2,000 or more, more preferably in the range of 2,000 to 70,000, and even more preferably in the range of 5,000 to 10,000. In addition, the dispersibility of component B1 is also the same as that of component A, preferably 6 or less, more preferably 3 or less, even more preferably 2 or less, and especially preferably 1.5 or less.

[0082] As demonstrated in the examples described later, the plasma treatment according to the present invention generates Si-alkyl radicals in the aforementioned alkyl-containing polysiloxane. These radicals transfer to the hydrophilic polymer, and the substrate surface is hydrophilized through the bond between the alkyl-containing polysiloxane and the hydrophilic polymer. Therefore, the substrate of the present invention only needs to be composed of a (co)polymer obtained by polymerizing a composition containing component A and, arbitrarily, component B1. Furthermore, as demonstrated in Reference Example 2 described later, the polymers of components A and B1 are locally present on the substrate surface, and the amount of radicals generated by the plasma treatment is not easily affected by the content of these components; even a relatively low content is sufficient for adequate hydrophilization. Therefore, the content of components A and B1 in the composition only needs to be 10% by mass or more, preferably 20% by mass or more, and more preferably 30% by mass or more. On the other hand, the content of these components is preferably determined in consideration of the required oxygen permeability, together with the content of other monomer components required to impart other properties. In this respect, it is usually 80% by mass or less, preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less.

[0083] As component B2, examples include fluoroalkyl (meth)acrylates, alkyl (meth)acrylates, dialkylaminoalkyl (meth)acrylates, diol (meth)acrylates, methyl acrylates, methyl acrylates having an aryl group, methyl acrylates having other additional double bonds, and other methyl acrylates.

[0084] As a fluoroalkyl (meth)acrylate, it is preferred to be a fluoroalkyl (meth)acrylate having 1 to 20 carbon atoms, and more preferably a fluoroalkyl (meth)acrylate having 1 to 10 carbon atoms.

[0085] The fluoroalkyl (meth)acrylate may be one type or a combination of two or more types. The fluoroalkyl (meth)acrylate may contain 0 to 80% by mass in the (macromolecule) monomer composition, preferably 10 to 75% by mass, more preferably 20 to 70% by mass, and even more preferably 30 to 65% by mass.

[0086] As an alkyl (meth)acrylate, it is preferred to be an alkyl (meth)acrylate having 1 to 20 carbon atoms, and more preferably an alkyl (meth)acrylate having 5 to 15 carbon atoms.

[0087] (Meth)acrylate may be one type or a combination of two or more types. The content of (meth)acrylate in the (macromolecule) monomer composition may be 0 to 30% by mass, preferably 2 to 20% by mass, and more preferably 3 to 10% by mass.

[0088] As a dialkylaminoalkyl ester of (meth)acrylate, it is preferred to be a (meth)acrylate having a dialkylaminoalkyl group having 3 to 20 carbon atoms, and more preferably a (meth)acrylate having an alkyl group having 4 to 10 carbon atoms.

[0089] As a (meth)acrylate, it is preferred to be a (meth)acrylate of an alkyldiol or alkoxydialkyldiol having 3 to 20 carbon atoms, and more preferably a (meth)acrylate of an alkyldiol or alkoxydialkyldiol having 5 to 10 carbon atoms.

[0090] As for (meth)acrylates containing an aryl group, those having a monocyclic or bicyclic aryl group having 5 to 12 carbon atoms are preferred, such as phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, and bisphenol A dimethacrylate. As for (meth)acrylates having other additional double bonds, those having vinyl, allyl, maleic acid, fumaric acid, itconic acid, crotonic acid, isocrotonic acid, or citrate residues are preferred, such as vinyl methacrylate. Other (meth)acrylates include, for example, trimethylolpropane trimethacrylate and neopentyl terephthalol tetramethacrylate.

[0091] The content of (meth)acrylate, (meth)acrylate having an aryl group, (meth)acrylate having other additional double bonds and other (meth)acrylates is generally less than 30% by mass in the (macro)monomer composition, preferably less than 20% by mass.

[0092] Examples of ingredients B3 include methacrylic acid, acrylic acid, itaconic acid, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxypropyl acrylate, glyceryl methacrylate, and polyethylene glycol methacrylate.

[0093] As component B4, examples include monomers having vinyl, allyl, maleic acid residues, fumaric acid residues, itaconic acid residues, crotonic acid residues, isocrotonic acid residues, or citrate residues, or monomers with such polymerizable reactive groups bonded to amides, preferably monomers having vinyl groups and monomers having polymerizable reactive groups with amide bonds.

[0094] The content of components B3 and B4 is determined according to the intended use of each monomer, and is independently included in the (macromolecule) monomer composition, and can be set to 0 to 50% by mass, preferably 1 to 40% by mass. In addition, details of (co)polymers having alkyl-containing polysiloxane structures and their manufacturing methods are described in Patent Documents 2, 3, 5, 8, 11 and 16, which are incorporated herein by reference.

[0095] The substrate may also contain ultraviolet absorbers, pigments, colorants, humectants, lubricants, pharmaceutical and nutritional supplements, compatibility agents, antibacterial agents, release agents, and other components. These components can be contained in non-reactive or copolymeric forms. For example, when ultraviolet absorbers are included, the eyes of the ophthalmic lens wearer can be protected from harmful ultraviolet rays. Furthermore, when colorants are included, the ophthalmic lens is colored, making it easier to identify and improving ease of use.

[0096] When an ultraviolet absorber is included, its content is 0.01 to 20 parts by weight, more preferably 0.05 to 10 parts by weight, and even more preferably 0.1 to 2 parts by weight, relative to 100 parts by weight of component A. When a colorant is included, its content is 0.00001 to 5 parts by weight, more preferably 0.0001 to 1 part by weight, and even more preferably 0.0001 to 0.5 parts by weight, relative to 100 parts by weight of component A.

[0097] To improve the compatibility of the components, (macromolecule) monomer compositions may contain any solvent. Furthermore, the mass percentage of each component in the composition indicates its content in a composition consisting solely of (macromolecule) monomers. There are no particular restrictions on the solvent, but it is preferable to use tertiary alcohols or saturated carboxylic acids.

[0098] In polymerization, thermal polymerization initiators or photopolymerization initiators can be used as needed. As thermal polymerization initiators, azo compounds or peroxides are preferred. Various benzodiazepine derivatives can be listed as photopolymerization initiators.

[0099] As a method for molding a substrate by polymerizing (macromolecule) monomers, known methods can be used. For example, methods that obtain a cylindrical or plate-shaped polymer and process it into a desired shape by cutting, mold polymerization, and rotational casting polymerization can be used.

[0100] 2. Plasma treatment In this invention, a substrate containing a (co)polymer with an alkyl-containing polysiloxane structure is plasma-treated in an inert gas environment without the use of a gas containing carbon or oxygen atoms. If the compound with the alkyl-containing polysiloxane structure is activated by plasma, Si· radicals or Si-alkyl (CnH2n)· radicals are generated. However, by using an inert gas, the radicals on the substrate surface are not stabilized by active species such as oxygen or carbon. As a result, the radicals generated on the substrate surface transfer to the hydrophilic polymer, and the hydrophilic polymer can be efficiently bonded to the substrate surface through the rebonding of these radicals.

[0101] Regarding alkyl-containing polysiloxane compounds, Si· radicals and Si-CnH2n· radicals can be formed by short-term irradiation with low-intensity plasma. On the other hand, if the plasma intensity is higher or the irradiation time is longer, amorphous silicon monoxide is more likely to be generated. When removed from the device, it is sometimes oxidized to glassy silicon dioxide (Non-Patent Document 4). Furthermore, among the generated radicals, Si-CnH2n· radicals are most prone to radical transfer to hydrophilic polymers (Non-Patent Document 4). Therefore, in order to form a large number of radicals on the substrate surface and increase the radical transfer to hydrophilic polymers, plasma treatment is preferably performed under mild conditions. On the other hand, if conditions are set to easily generate Si radicals, cross-linking between alkyl-containing polysiloxane compounds becomes easier due to the condensation of silanol groups. If a hydrophilic polymer is present nearby during this condensation, the hydrophilic polymer will be drawn into the condensation reaction and become entangled with the alkyl-containing polysiloxane compound, thus improving the structure's resistance to friction. Therefore, from this perspective, plasma treatment conditions are also preferable.

[0102] As inert gases, N₂, Ar, He, and Ne can be used, with N₂ being the preferred one. He-based gases have lower atomic weights, allowing for the generation of stable plasmas with lower power. However, as rare gases, they are more expensive. The same applies to Ne. Ar is abundant in air, but it is not necessarily superior to N₂.

[0103] Low-frequency discharge and glow discharge are preferred methods for generating plasma. Low-frequency discharge is preferably 10kHz to 10Hz, more preferably below 1kHz, and even more preferably below 100Hz. Such low-frequency discharge is conveniently located at 50Hz or 60Hz, which can be supplied by commercial power sources.

[0104] The optimal power varies depending on the electrode size, but is generally sufficient in the range of 10-150W, more preferably 60-120W, and ideally 70-100W. For parallel plate electrodes with a diameter of approximately 10cm, 20-100W is preferred, more preferably 30-80W. For parallel plate electrodes with a diameter of 20cm, 40-150W is preferred, more preferably 60-120W, and ideally 70-100W.

[0105] The optimal plasma irradiation time depends on the introduction and exhaust rates of the inert gas, which will be discussed later. Generally, a time between 5 seconds and 2 minutes is sufficient. From the perspective of improving hydrophilicity, production efficiency, and the introduction of silanol condensation reactions between alkyl-containing polysiloxane compounds, a time between 20 seconds and 1 minute and 30 seconds is preferred, and 20 to 1 minute is even more preferred.

[0106] For glow discharge, it is preferable to generate plasma with a voltage of 300~800V and a current of 3~30mA. In addition, for glow discharge, the plasma irradiation time usually only needs to be set between 1 second and 1 minute, preferably between 3 seconds and 20 seconds, and more preferably between 7~15 seconds.

[0107] If the inert gas introduction and exhaust rates increase, the proportion of inert gas relative to the plasma will increase, while the gas temperature will decrease, leading to a reduction in plasma concentration. Therefore, the plasma intensity also depends on the inert gas introduction and exhaust rates; increasing these rates can decrease the plasma intensity. The optimal values ​​depend on the plasma irradiation time. Excessively fast gas introduction rates may result in uneven plasma spatial intensity, but this effect is less pronounced for inert gases such as N₂, Ar, He, and Ne due to their higher diffusion rates. The inert gas introduction and exhaust rates can be described by the pressure and amount of inert gas introduced during plasma generation, and can be used as indicators to replace the inert gas introduction and exhaust rates. Therefore, the inert gas pressure is preferably determined within the range of 1 Pa to 50 Pa, more preferably within the range of 2 Pa to 30 Pa, and even more preferably within the range of 5 Pa to 25 Pa, depending on the plasma irradiation time. Furthermore, the inert gas introduction amount is preferably within the range of 1 sccm to 100 sccm, more preferably within the range of 3 sccm to 50 sccm, and even more preferably within the range of 5 sccm to 30 sccm.

[0108] By performing plasma treatment in an inert gas environment according to the present invention, a greater number of free radicals can be formed on the substrate surface. More specifically, immediately after plasma treatment, at least 20% of the alkyl-containing polysiloxane units present on the substrate surface can form free radicals. Specifically, if the substrate is exposed to plasma in an inert gas environment under the aforementioned mild conditions, at least 14% of the Si atoms of the alkyl-containing polysiloxane units present on the substrate surface can be converted into Si· free radicals. Furthermore, at least 11% of the alkyl groups (e.g., methyl groups) of the alkyl-containing polysiloxane units present on the surface of the compound can be converted into Si-CnH2n· free radicals. Thus, when the number of alkyl groups in the alkyl-containing polysiloxane units is two, by selecting better plasma treatment conditions, at least 36% of the alkyl-containing polysiloxane units present on the substrate surface can form free radicals, most of which can be utilized for bonding with the hydrophilic polymers described later. Here, "X present on the surface as alkyl-containing siloxane units" means X (e.g., Si atoms or methyl groups) that can be measured when the substrate is subjected to XPS analysis using an XPS device such as EnviroESCA at a water vapor pressure of 5 mbar. The detector angle is 70°, and the XPS detection depth in this case is approximately 5 nm.

[0109] In XPS measurements of the Si region of the ophthalmic soft lens obtained under the aforementioned mild plasma treatment conditions, the Si 2p peak was sharp, and the full width at half maximum (FWHM) value became less than 2.1 eV. This indicates limited oxidation of Si atoms in the alkyl-containing siloxane units present on the surface. Furthermore, when the Si 2p peak was curve-fitted for each oxidation state, more than 60% of the Si atoms present on the surface were bonded to two O atoms and were not oxidized from the original PDMS state. Accordingly, it has the characteristics of inhibiting the oxidation of alkyl-containing siloxanes and forming more free radicals on the substrate surface.

[0110] When the substrate is placed in an oxygen-containing environment after plasma treatment, Si-CnH2n· free radicals react with oxygen to irreversibly form Si-CnH2n-OO· free radicals. These free radicals stabilize for several minutes, pulling out hydrogen from hydrophilic polymers that readily form free radicals, resulting in free radical transfer. Furthermore, these free radicals can be re-bonded with the free radicals of hydrophilic polymers, thus enabling the bonding of hydrophilic polymers to the substrate (Non-Patent Documents 5 and 6). On the other hand, Si· radicals can also react irreversibly with oxygen to form Si-OO· radicals. These radicals cause radical transfer to hydrophilic polymers and simultaneously bond with the hydrophilic polymers to form Si-OOR (R represents a hydrocarbon in the hydrophilic polymer). However, this structure is unstable and will eventually dissociate to become Si-OH (Non-Patent Document 5). Furthermore, if Si-CnH2n· radicals are exposed to oxygen for several hours, they will convert to Si-CnH2n-OH and bond to the OC=O of Si. [In the formula, R3 and R4 represent alkyl groups, and R5 represents an alkyl group. Preferred alkyl groups are the same as or correspond to R1 and R2 in formula (1).]

[0111] The proportion of Si-C nH 2nOH can be more than 8% of the alkyl (e.g., methyl) of the alkyl-containing silicate units present on the substrate surface, and OC=O can be more than 3%, which brings hydrophilicity to the substrate surface. If exposed to an oxygen-containing environment as is, the hydrophobic silicate portion will move to the surface and make the substrate surface hydrophobic. More specifically, the hydrophilic group system of the above formula (2) begins to form a few minutes after free radical irradiation, and then the substrate surface slowly becomes hydrophobic. Therefore, if the plasma-treated substrate is placed in an oxygen-containing environment for an extended period, the overall number of free radicals bonded to the substrate by the hydrophilic polymer decreases, reducing the bonding efficiency between the hydrophilic polymer and the substrate, which is therefore less desirable. On the other hand, in order to utilize Si-CnH2n-OO· free radicals to generate bonds with hydrophilic polymers more efficiently, it is preferable to expose the substrate to an oxygen-containing environment for only a short time after plasma treatment. For example, by exposing the substrate to an oxygen-containing environment for less than 10 seconds, Si-CnH2n-OO· free radicals can be utilized; more preferably, exposure to an oxygen-containing environment for less than 5 seconds; and even more preferably, exposure to an oxygen-containing environment for less than 3 seconds. Furthermore, from the same perspective, if a long period of time is required from plasma treatment until immersion in a hydrophilic polymer solution, it is preferable to place the substrate in an oxygen concentration of less than 1% by mass, preferably in an inert gas environment.

[0112] 3. Hydrophilic treatment with hydrophilic polymers In this invention, the substrate after plasma treatment is immersed in an aqueous solution of a hydrophilic polymer to hydrophilize the substrate surface. More specifically, the substrate, on which Si· free radicals, Si-CnH2n· free radicals, and optionally Si-CnH2n-OO· free radicals are formed on the surface through plasma treatment, is immersed in an aqueous solution of a hydrophilic polymer. Due to the Si-CnH2n· free radicals on the substrate surface and, depending on the situation, Si-CnH2n-OO· free radicals, free radicals are transferred to the hydrophilic polymer. Through the rebonding of the free radicals generated by the substrate and the hydrophilic polymer, the two are bonded together. Therefore, hydrophilic polymers, which generate hydrogen through free radicals on the substrate surface, must be compounds capable of forming free radicals. This is demonstrated in the examples described later; even decane, which belongs to the alkane family, can be bonded to alkyl-containing polysiloxane compounds that form Si-CnH2n· free radicals (typically Si-CH2· free radicals) through plasma treatment. That is, any compound containing a structure capable of resonating with free radicals on carbon atoms can be bonded to alkyl-containing polysiloxane compounds using this invention, regardless of whether it is a hydrophilic polymer.

[0113] Therefore, as a hydrophilic polymer, any structure that can resonate with the free radicals on the carbon atom can be utilized in various ways. Examples include polyvinylpyrrolidone (PVP), polyacrylamide, and compounds in which the nitrogen atom of polyacrylamide is substituted with an alkyl group (e.g., an alkyl group having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms) (e.g., poly(N,N-diethylacrylamide), poly(N,N-dimethylacrylamide), poly(N-isopropylacrylamide) etc.), poly(N-vinylacetamide), poly(N-vinylformaldehyde), poly(N-vinylisobutyrate acrylamide), poly(2-... (azoline), poly(2-ethyl-2-) (e.g., oxazoline), polyacrylic acid, compounds having hydrophilic groups (e.g., hydroxyethyl) on the oxygen atom of polyacrylic acid (e.g., HEMA), polymethacrylic acid, polylysine, polymaleic acid, alginate, chondroitin sulfate, pectin, hyaluronic acid, chitosan, polysialic acid, pullulan, dextran, cellulose, polyethylene glycol (PEG), block copolymers containing PEG (e.g., block copolymers of PEG and polyacrylic acid, block copolymers of PEG and polyamino acids such as polylactic acid), surfactants containing PEG (PEG with a long-chain alkyl group at one end), polymers with PEG-terminated ends (e.g., PEG with methyl, ethyl, benzyl, dibenzylpropyl, dimethylaminoethyl, etc. at the end), polyphosphatidylcholine, polytetrahydrofuran, polyvinyl alcohol, polymethyl vinyl ether, polyethyleneimine (PEI), polyallylamine, polydiallylamine, polymethyldiallylamine, poly(N-vinylamine), poly(vinyl-N-methylpyridinium salt), polyvinylphosphonic acid, polyvinylsulfonic acid, polystyrene sulfonic acid, polystyrene sulfonate, poly(3-sulfopropyl potassium methacrylate), hydroxyethyl cellulose, hydroxypropyl methylcellulose, polydimethyldiallyl ammonium salt, poly(vinyl methacrylate), poly(2-vinylpyridine-N-oxide), and copolymers obtained by crosslinking two or more of these hydrophilic polymers (e.g., ethylene glycol crosslinked polymers of polyacrylic acid (e.g., CLPAH-100)) and (co)polymers having such hydrophilic polymers as branched structures and being hydrophilic (e.g., PEG derivatives obtained by bonding at least one of these hydrophilic polymers as branched structures to PEG).

[0114] However, the ease with which free radicals generated on the substrate surface transfer to hydrophilic polymers varies depending on the type of hydrophilic polymer. Furthermore, the reactivity of the free radicals generated via free radical transfer differs between the type of hydrophilic polymer and the free radicals of alkyl-containing polysiloxane compounds. Compounds with carbon atoms (usually alkyl and / or alkyl and / or methine carbons) that can resonate with atoms with non-shared electron pairs (e.g., oxygen, nitrogen) or double bonds are more likely to undergo free radical reactions with Si-C nH 2n·. Compounds with two carbon atoms that can resonate with atoms with non-shared electron pairs (e.g., oxygen, nitrogen) or double bonds, or carbon atoms that can resonate with atoms with non-shared electron pairs (e.g., oxygen, nitrogen) and double bonds, also undergo free radical transfer via Si-C nH 2n-OO·, reacting with various free radicals (Si·, Si-C nH 2n·, Si-C nH 2n-OO·) on the substrate to re-bond.

[0115] Furthermore, for free radical transfer and rebonding to occur, hydrophilic polymers must be close to the free radicals on the substrate surface. However, in cases where the polymer backbone contains aromatic rings or exhibits a rigid structure, free radical transfer and rebonding can sometimes be difficult. Therefore, compounds whose polymer backbone does not contain aromatic rings are preferable. Additionally, alkyl-containing siloxane units are negatively charged, making it more difficult for anionic polymers to approach the surface. Therefore, compounds that do not contain anionic groups are preferable. However, this problem can be solved by adjusting the pH or salt concentration of the polymer's aqueous solution to suppress charge repulsion.

[0116] Therefore, the hydrophilic polymer used in this invention is preferably selected from these viewpoints. Examples of preferred hydrophilic polymers include, for example, polyvinylpyrrolidone (PVP), polyacrylamide, and compounds in which the nitrogen atom of polyacrylamide is substituted with an alkyl group (e.g., an alkyl group having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms) (e.g., poly(N,N-diethylacrylamide), poly(N,N-dimethylacrylamide), poly(N-isopropylacrylamide) etc.), poly(N-vinylacetamide), poly(N-vinylformaldehyde), poly(N-vinylisobutyrate amide), polyacrylamide epichlorohydrin, poly(2- (azoline), poly(2-ethyl-2-) (e.g., oxazoline), polyacrylic acid, compounds having a hydrophilic group (e.g., hydroxyethyl) on the oxygen atom of polyacrylic acid (e.g., HEMA), polymethacrylic acid, polylysine, polymaleic acid, alginate, chondroitin sulfate, pectin, hyaluronic acid, chitosan, polysialic acid, pullulan, dextran, cellulose, polyethylene glycol (PEG), block copolymers containing PEG (e.g., block copolymers of PEG and polyacrylic acid, block copolymers of PEG and polyamino acids such as polylactic acid), surfactants containing PEG (PEG with a long-chain alkyl group at one end), and polymers with PEG-terminated ends (e.g., PE with methyl, ethyl, benzyl, dibenzylpropyl, dimethylaminoethyl, etc. at the ends). G, etc.), polyphosphatidylcholine, polytetrahydrofuran, polyvinyl alcohol, polymethyl vinyl ether, polyethyleneimine (PEI), polyallylamine, polydiallylamine, polymethyldiallylamine, poly(N-vinylamine), poly(vinyl-N-methylpyridinium salt), polyvinyl phosphate, polyvinyl sulfonic acid, polystyrene sulfonic acid, polystyrene sulfonate, poly(3-sulfopropyl potassium methacrylate), hydroxyethyl cellulose, hydroxypropyl methyl cellulose, and copolymers obtained by crosslinking two or more of these hydrophilic polymers and (co)polymers having such hydrophilic polymers as branched structures and being hydrophilic (e.g., PEG derivatives obtained by bonding at least one of these hydrophilic polymers as a branched structure to PEG).

[0117] From the same point of view, the preferred alternatives are polyvinylpyrrolidone, polyacrylic acid, ethylene glycol crosslinked polyacrylic acid, starch graft polymers of polyacrylic acid, PEG, block copolymers containing PEG, alginate, chondroitin sulfate, hyaluronic acid, pectin, hydroxyethyl cellulose, dextran, polyvinyl alcohol, polyethyleneimine, polyglutamic acid, or polyacrylamide, and particularly preferred are polyvinylpyrrolidone, ethylene glycol crosslinked polyacrylic acid, polyacrylic acid, chondroitin sulfate, hydroxyethyl cellulose, polyvinyl alcohol, block copolymers containing PEG, and PEG.

[0118] In addition, CLPAH-100 is a copolymer of PEG with vinyl groups at both ends and acrylic acid, and its molecular structure is as follows. In the formula, R6 represents a polyethylene glycol chain.

[0119] Organic solvents with CH bonds are unusable as solvents for hydrophilic polymer solutions because they can generate free radical transfer from Si-CnH2n· radicals; therefore, water is preferred. Furthermore, while Si· radicals are relatively stable in water, they slowly form Si-OH groups at high temperatures. On the other hand, sufficient time and temperature are required for a complete reaction between the hydrophilic polymer and the substrate. Therefore, impregnation in the hydrophilic polymer solution is preferably performed at a temperature of 5–50°C for approximately 20 minutes to 3 hours, more preferably at a temperature of 10–30°C for approximately 30 minutes to 1 hour. Additionally, when the temperature is set lower, the impregnation time is preferably increased; when the temperature is set higher, the impregnation time is preferably shortened.

[0120] The concentration of hydrophilic polymers in solution varies depending on the type of hydrophilic polymer, and is usually set between 0.01 and 1% by mass, with 0.1 to 0.3% by mass being preferred in most cases. Furthermore, in cases where there are insoluble substances in the polymer solution, filtration is preferably performed using filter paper, for example, capable of separating particles with a retention particle size of a few micrometers.

[0121] The thickness of the hydrophilic polymer layer can be controlled within the range of approximately 1 nm to several μm, depending on the type of hydrophilic polymer. For example, a hydrophilic polymer layer with a thickness of less than 5 nm (typically 1 nm to 5 nm) can be obtained by selecting a hydrophilic polymer without a cross-linked structure. Furthermore, a hydrophilic polymer layer with a thickness of 6 nm to 5 μm can be obtained by selecting a hydrophilic polymer with a cross-linked structure (e.g., CLPAH-100, a cross-linked polymer of polyacrylic acid and starch, a cross-linked polymer of polyacrylic acid and polyamide chlorohydrin, etc.). In this case, the thickness of the hydrophilic polymer layer can also be controlled by adjusting the cross-linking density. Additionally, in the case of hydrophilic polymers with cross-linked structures, the thickness of the hydrophilic polymer layer can also be controlled by using an aqueous solution obtained by reducing the cross-linking structure through ultrasonic irradiation and filtering it through a filter with appropriately fine pores.

[0122] After plasma treatment, the environment before immersion in a hydrophilic polymer solution can also be set as an inert gas environment, preferably an oxygen-containing environment. If immersion is carried out in an environment containing a certain level of oxygen, effective hydrophilization can be achieved using Si-C nH 2n-OO· free radicals (e.g., Si-CH 2-OO· free radicals). At this point, the optimal oxygen concentration in the environment is 0.5–20% by mass, more preferably 0.7–15% by mass, and ideally 0.8–10% by mass.

[0123] Depending on the impregnation conditions, additional heat treatment may also be performed. By inducing the reaction of any remaining unreacted free radicals, the bond between the hydrophilic polymer and the substrate can be made denser. This additional heat treatment can be performed at relatively high temperatures, for example, at 80°C to 135°C for 20 minutes to 2 hours, preferably at 80°C to 135°C for 30 minutes to 1 hour.

[0124] Following the hydrophilic treatment described above, the resulting lens can be arbitrarily heated and sterilized. In this invention, since the substrate and the hydrophilic polymer form stable covalent bonds, sterilization can be performed using an autoclave. Heat sterilization can be performed, for example, by immersing the lens in water or a buffer solution (specifically, a lens preservation solution) and typically by heating at 121°C for 30 minutes under pressure. Depending on the immersion conditions, this sterilization process can sometimes produce the same effect as the additional heat treatment described above, and is therefore also advantageous in this respect.

[0125] 4. Soft ophthalmic lenses After the above-mentioned hydrophilic treatment or heat treatment, the soft ophthalmic lens of the present invention is obtained. The lens obtained by performing the above-mentioned plasma treatment and hydrophilic treatment comprises: an ophthalmic lens substrate comprising a (co)polymer having an alkyl-containing polysiloxane structure, and a single coating comprising a hydrophilic polymer on the surface of the substrate, which, although a single coating, has high hydrophilicity.

[0126] As described above, in one embodiment, the substrate is composed of a (co)polymer obtained by polymerizing a (macromolecule) monomer composition containing a polymerizable siloxane in a proportion of 10% by mass or more, preferably 20% by mass or more, and more preferably 30% by mass or more. The substrate containing a large amount of polysiloxane structure has high oxygen permeability; in a preferred embodiment, the lens of the present invention has an oxygen permeability (Dk value) of 150 or more. On the other hand, the alkyl-containing siloxane, as described above, is locally present on the substrate surface due to its hydrophobic and water-repellent properties; even a relatively small amount can generate more free radicals on the substrate surface through plasma treatment. As mentioned above, hydrophilic polymers are also bonded to the alkyl-containing polysiloxane structure of the substrate through the rebonding of free radicals, playing a role in retaining moisture on the lens surface.

[0127] The hydrophilicity resulting from a single coating can be confirmed by various parameters. The presence of surface-adsorbed water can be confirmed by XPS analysis at a water vapor pressure of 5 mbar, which can be assessed as resulting in higher hydrophilicity. Furthermore, in one embodiment of the lens according to the present invention, the water contact angle of the coating surface is 70° or less; in a preferred embodiment, the water contact angle is less than 60°; in a more preferred embodiment, the water contact angle is less than 50°; and in a still more preferred embodiment, the water contact angle is less than 40°. Here, in this specification, the term "water contact angle" refers to the angle between the water droplet and the lens surface when a water droplet is added to the lens surface, calculated using the method of inclination. Specifically, 1.5 μL of ion-exchanged water is added to the surface of a coated lens, and immediately after the addition, a photograph is taken of the shape of the droplet from its static state from the side. The contact angle is determined from the photographed droplet shape using the method of inclination.

[0128] Furthermore, the lens of the present invention connects the substrate and the hydrophilic polymer through a large number of covalent bonds, thus exhibiting excellent coating friction resistance. Specifically, in one embodiment of the lens according to the present invention, the water contact angle after 20 friction tests is less than 80°; in a more preferred embodiment, the water contact angle after 20 friction tests is 70° or less; in an even more preferred embodiment, the water contact angle after 20 friction tests is 60° or less; in a still more preferred embodiment, the water contact angle after 20 friction tests is 50° or less; and in a particularly preferred embodiment, the water contact angle after 200 friction tests is 50° or less. In this specification, "friction test" refers to the test in which the sample is wetted with pure water, and the sample is rubbed a certain number of times (e.g., 20 times or 200 times) while wearing nitrile rubber gloves. After being washed with pure water and the water adhering to the surface is wiped off, purified water is added, and the water contact angle is measured by the above-mentioned wiring method.

[0129] Regarding the lens of the present invention, the substrate surface can be sufficiently hydrophilicized by a single coating, thus the coating thickness can be set to 1 nm to 5 nm. However, the thickness can also be increased by adsorbing cross-linked polymers, in which case the coating thickness can be set to the range of 6 nm to 5 μm.

[0130] Here, the conceptual structure of the lens of the present invention is illustrated in FIG1. ​​The lens substrate comprises a (co)polymer having an alkyl-containing polysiloxane structure, which is obtained by polymerizing a polysiloxane compound having polymerizable functional groups and alkyl groups, or such compounds with other polymerizable compounds. If such a lens substrate is subjected to plasma treatment, Si· radicals, Si-CnH2n· radicals, and Si-CnH2n-OO· radicals are generated on the substrate surface when exposed to the above-mentioned oxygen-containing environment. The Si-CnH2n· radicals and, if applicable, Si-CnH2n-OO· radicals are transferred to the hydrophilic polymer. The portion having the alkyl-containing polysiloxane structure is bonded to the hydrophilic polymer via the following formula (4) and, if applicable, formulas (5) and (6). (In the formula, R7 represents an alkyl group, R8 represents an alkyl group, and X1 represents a carbon atom in a hydrophilic polymer.)

[0131] (In the formula, R9 represents an alkyl group, R10 represents an alkyl group, and X2 represents the carbon atom of a hydrophilic polymer.) (In the formula, R11 represents an alkyl group, and X3 represents the carbon atom of a hydrophilic polymer.)

[0132] The bonding method of formula (5) is generated when the substrate is exposed to an oxygen-containing environment for a short time after plasma treatment, or when hydrophilic treatment is performed in an oxygen-containing environment, and a water-soluble polymer that is more likely to form free radicals is selected (e.g., a hydrophilic polymer with atoms or double bonds that have non-covalent bond pairs). The carbon system of the hydrophilic polymer adjacent to the atoms or double bonds that have non-covalent bond pairs is bonded to the oxygen of the Si-alkyl-OO of the substrate.

[0133] The bonding method of formula (6) is generated when a water-soluble polymer that is more likely to form free radicals is selected (a hydrophilic polymer with two atoms or double bonds with non-covalent bonds, or a hydrophilic polymer with atoms and double bonds with non-covalent bonds, such as PVP). The carbon system of the hydrophilic polymer adjacent to the atoms or double bonds with non-covalent bonds is bonded to the Si of the substrate.

[0134] Furthermore, the Si radicals formed near the surface of the lens substrate eventually form Si-OH groups (silanol groups), which undergo dehydration condensation as shown below. As a result, the (co)polymer with a polysiloxane structure is cross-linked via siloxane bonds (Si-O-Si). If a hydrophilic polymer is present nearby during the condensation reaction, the hydrophilic polymer will become entangled with the (co)polymer with the cross-linked polysiloxane structure, thus improving friction resistance. Furthermore, siloxane bonds are also formed inside the contact lens below the bonding region. It is generally believed that due to the condensation of these silanol groups, the diffusion of hydrophobic polymers to the surface is inhibited.

[0135] If we use a substrate containing PDMS and PVP as a hydrophilic polymer as an example, Si· radicals, Si-CH 2· radicals and Si-CH 2-OO· radicals are generated on the surface of the substrate by plasma treatment. The Si-CH 2· radicals and, depending on the situation, Si-CH 2-OO· radicals are transferred to PVP to generate the following radicals. Through the rebonding of the radicals of the substrate and PVP, the above formulas (4) and (6), or covalent bonds of (4) to (6) are formed.

[0136] When polyethylene glycol (PEG) is used as a hydrophilic polymer, free radicals are easily formed by free radical transfer, which pulls out hydrogen from the methylene group adjacent to the oxygen atom. These free radicals mainly form the covalent bonds of formulas (4) and (6) above, or (4) to (6). In the case of PEG, since all methylene groups are equivalent, the free radicals transferred to the methylene groups can resonate with the two oxygen atoms, making it easier for them to re-bond to Si· free radicals.

[0137] The lens of this invention uses a large number of covalent bonds to support a hydrophilic polymer on a substrate, thereby retaining water on the lens surface. In a preferred embodiment of the lens, at least 5% of the alkyl-containing silicate units present on the substrate surface are bonded to the C of the hydrophilic polymer. In a more preferred embodiment, at least 10% of the alkyl-containing silicate units present on the substrate surface are bonded to the C of the hydrophilic polymer.

[0138] According to the above method, the present invention enables the secure and efficient coating of hydrophilic polymers onto a substrate via a free radical rebonding mechanism. As a result, while increasing oxygen permeability and reducing dryness during wear due to the increased polysiloxane content, the lens surface is also sufficiently hydrophilized, allowing for long-term wear without discomfort. Furthermore, because the hydrophilic polymer is covalently bonded to the substrate through extensive free radical rebonding, the coating exhibits excellent scratch resistance, allowing for lens reuse. Moreover, since hydrophilization can be achieved with a single hydrophilic polymer layer, the manufacturing process is simplified, improving productivity. [Example]

[0139] The invention will be further illustrated below with reference to the following examples, but the invention is not limited thereto. In the embodiments, "%" represents mass%.

[0140] 1. Evaluation of surface chemical changes and hydrophilicity using a substrate made solely of PDMS rubber after plasma treatment and coating with different compounds. This experiment aimed to clarify how the surface of hydrocarbon-containing polysiloxanes undergoes chemical changes due to plasma with an inert gas, and what properties this results in. Furthermore, the surface properties of plasma-treated polysiloxanes coated with three compounds—PVP, PEG, and decane—were compared.

[0141] 1-1. Substrate modulation [Synthesis example 1] In this experiment, a thin-film PDMS rubber was used as the substrate. The PDMS rubber was prepared using PDMS with vinyl groups at both ends (trade name: SYLGARD184, Silicon Elastomer, manufactured by DOW Corporation, weight average molecular weight: 48000) as the crosslinking agent, and PDMS with hydrogen silicon groups in the molecule (the aforementioned SYLGARD184 crosslinking liquid, weight average molecular weight: 3500) as the crosslinking agent, in the presence of a platinum catalyst. The PDMS with vinyl groups at both ends and the crosslinking agent were mixed at a mass ratio of 20:1, and after vacuum degassing, a film with a thickness of 0.15 mm was formed. The crosslinking reaction was then carried out by heating at 90°C for 1 hour. This produced PMDS rubber with the same strength as a flexible contact lens. This PMDS rubber was cut to appropriate dimensions for the plasma treatment and coating described below.

[0142] 1-2. Plasma treatment and coating [Example 1] After plasma treatment, the PDMS rubber was immersed in a PVP aqueous solution and coated onto the sample surface. The plasma treatment was performed using a plasma generation device (manufactured by Kuei Semiconductor Co., Ltd., trade name: YHS-DC100) with two 10cm diameter circular flat electrodes spaced 5cm apart in parallel within a chamber. The sample was placed between the electrodes, and after vacuum substitution within the chamber, nitrogen gas was introduced, and the sample was irradiated with plasma at a pressure of 20Pa for 30 seconds. The nitrogen flow rate was set to 10 sccm, and the output power was set to 50W. After plasma irradiation, nitrogen gas was introduced to restore the chamber to atmospheric pressure. The plasma-treated PDMS rubber was then immersed in a PVP aqueous solution (0.2% by mass, weight average molecular weight 40,000) under nitrogen conditions for 30 minutes.

[0143] [Example 2] Following the same procedure as in Example 1, the plasma-treated PDMS rubber was immersed in a PEG aqueous solution (0.2% by mass, weight average molecular weight 1,000) under a nitrogen environment and left for 30 minutes.

[0144] [Reference Example 1] Following the same procedure as in Example 1, the plasma-treated PDMS rubber was placed in decane under a nitrogen environment and impregnated for 30 minutes. Unbonded decane was removed with ethanol and then dried.

[0145] 1-3. Characteristic Evaluation 1-3-1. Assessment of hydrophilicity via water contact angle (1) Test methods The water contact angles of the samples obtained in Examples 1 and 2 and Reference Example 1 were measured using 1.5 μL of ion-exchanged water. As a control, the contact angles of the substrate before plasma treatment were also measured. The water contact angle is determined by adding 1.5 μL of ion-exchanged water to the surface of a coated lens, taking a photograph of the droplet's shape from the side immediately after the addition, and then determining the droplet's shape using the indentation method.

[0146] (2) Test Results The results of the water contact angle measurements for each sample are summarized below.

[0147] These experimental results indicate that treating PDMS rubber with an inert gas plasma highly activates the PDMS rubber surface, resulting in the bonding of PVP, PEG, and decane. The common structure of these adsorbed substances is CH bonding, suggesting that the free radicals capable of activating CH bonds are... The free radical is generated by the -Si(CH 3) 2-O- radical. The most likely free radical is the Si-CH 2· radical (non-patent literature 4), which can be predicted to undergo free radical transfer between the CH group of the adsorbent and the adsorbent, thereby generating free radicals on the carbon atoms of the adsorbent, which then rebond with the Si-CH 2· radicals or silicon free radicals (Si·) on the PDMS rubber surface.

[0148] 1-3-2. Evaluation of hydrophilicity level and bonding mode as determined by XPS For the samples obtained in Examples 1, 2, and Reference Example 1, as well as PDMS rubber before and after plasma treatment, a near-atmospheric pressure X-ray photoelectron spectrophotometer (XPS) (Tokyo Instrument Co., Ltd., EnviroESCA, monochromatic AlKα X-rays (1486.6 eV, 42 W), passing energy (30 eV)) was used to analyze the adsorption of water molecules on the sample surface and the bonding mode between the substrate and the coating. The XPS measurements were performed within two days of sample preparation.

[0149] The vapor pressure of water at room temperature is 25 mbar. First, the surface of each sample was measured by XPS at a water vapor pressure of 20 mbar. (1) Substrate (PDMS rubber before plasma treatment), (2) PDMS rubber after plasma treatment by the method described in Example 1, (3) Sample of Example 1 (PDMS rubber obtained by adsorbing PVP after plasma treatment), (4) Sample of Example 2 (PDMS rubber obtained by adsorbing PEG after plasma treatment), and (5) Sample of Reference Example 1 (PDMS rubber obtained by adsorbing decane after plasma treatment) were all confirmed to have water adsorption.

[0150] Secondly, XPS measurements were performed on the surfaces of each sample at water vapor pressures of 20 mbar, 15 mbar, 10 mbar, 8 mbar, and 5 mbar. For the hydrophobic surface model, the sample from Reference Example 1 (PDMS rubber obtained by adsorbing decane after plasma treatment) was used, and for the hydrophilic surface model, the sample from Example 2 (PDMS rubber obtained by adsorbing PEG after plasma treatment) was used. The results showed that both decane-modified PDMS rubber and PEG-modified PDMS rubber exhibited water adsorption up to 8 mbar, but no adsorption occurred at 5 mbar. This indicates that water adsorption up to 8 mbar is unimolecular adsorption (Langmuir adsorption), and both the surfaces of decane-modified PDMS rubber and PEG-modified PDMS rubber possess the same level of Lennard-Jones potential. On the other hand, the peak value of water on the surface of PEG-modified PDMS rubber shifted from 534.6 eV (20 mbar) to 534.2 eV (8 mbar), and the peak area also decreased by about one-third. It can be considered that the above-mentioned shift of 0.4 eV is due to the change in the charged state of the sample as the adsorbed water decreases. On the other hand, regarding the sample from Example 1, it was confirmed that water molecule adsorption also occurred at 5 mbar (Figure 2, Table 2). Furthermore, the water molecule peak was very sharp, with a full width at half maximum (FWHM) of 0.63 eV. This indicates that the water molecules were not condensed liquids, but rather adsorbed in a near-gas state. The adsorption force of the PVP surface for water molecules was very strong. Furthermore, the XPS results described above do not indicate that PEG modification is unsuitable for hydrophilicizing PDMS. PEG-modified PDMS rubber exhibited a contact angle of 55.8° immediately after preparation. After exposure to air for 90 minutes, the contact angle increased to 74.7°, and further to 90.4° after 22 hours. This indicates that the PEG on the surface is easily embedded in the PDMS rubber, while the PDMS is easily exposed to the surface. The XPS measurements were performed between 24 and 48 hours after sample preparation, during which time the PEG surface is highly likely to become hydrophobic. That is, as long as both PEG and PVP modification are performed immediately after preparation, they exhibit sufficient hydrophilicity; if exposed to air, the former easily becomes hydrophobic, while the latter is less likely to do so. However, in the case of the former (Example 2), hydrophilicity can be maintained for a long time by storing in water.

[0151] XPS measurements at 5 mbar water vapor pressure confirmed the presence of carbonyl carbon in the O=CN bonds of the PVP side chains in the C1s region of the sample from Example 1 (PDMS rubber obtained by adsorbing PVP after plasma treatment) at 287.76 eV. This is illustrated in Figure 3. Assuming all carbonyl carbon originates from PVP, the detected carbonyl carbon content (10.1%) suggests a PVP layer thickness of approximately 2.0 nm. However, in reality, not all free radicals transferred to PVP are rebonded to PDMS; some may be oxidized. Furthermore, free radicals on the methyl groups of PDMS may also be oxidized. Therefore, the actual thickness of the PVP layer can be considered to be approximately 1 nm. On the other hand, in the sample of Example 2 (PDMS rubber obtained by adsorbing PEG after plasma treatment), the presence of ether carbon in the -(CH2-CH2-O)- unit of the main chain was confirmed at 286.22 eV. This is shown in Figure 4. Judging from the amount of ether carbon detected (35.5%), it can be considered that a PEG layer with a thickness of about 1.5 nm has been formed. In the case of PEG, since all carbon atoms are bonded to oxygen, the proportion of carbon bonded to oxygen in the C1s region becomes very high.

[0152] The XPS results for each sample in the C1s and O1s regions are summarized in Table 2. In the substrate (PDMS rubber before plasma treatment), methyl carbon bonded to silicon was observed only at 284.38 eV. After plasma treatment, carbon atoms bonded to oxygen or carbon atoms in O=CO(N) formation were confirmed. Comparing the data before and after plasma treatment revealed that 11.5% of the methyl carbon was free radicalized due to plasma. Interestingly, comparing the data before and after impregnation in decane, the proportion of carbon atoms bonded to oxygen or more oxidized carbon atoms decreased to 7.8%. This indicates that the free radical transfer of methyl groups in PDMS is reduced, preventing oxidation. It should be noted in Table 2 that in the plasma-treated PDMS rubber, 8.3% of the carbon is bonded to one oxygen atom, 3.2% is bonded to two oxygen atom, and the remaining 88.5% of the carbon is not oxidized. That is, the plasma treatment was performed under the same conditions in Example 1 and Example 2, therefore it can also be considered that in these samples, 11.5% of the methyl groups formed Si-CH₂· radicals, while the remaining methyl groups (88.5%) did not generate Si-CH₂· radicals immediately after the plasma treatment. In other words, the plasma treatment conditions of the present invention are very mild.

[0153] The XPS measurements of the N 1s and Si 2p regions of each sample are summarized in Table 3. Furthermore, Figures 5, 6, 7, and 8 show the XPS spectra of the Si 2p regions obtained from the samples of each Synthetic Example 1 (PDMS rubber), the sample obtained by plasma treatment of the substrate of Synthetic Example 1, the sample of Example 1, and the sample of Reference Example 1. Furthermore, in this XPS measurement, due to the change in the oxidation state of Si, the charge systems of Si and O in the PDMS backbone are slightly different from those of N or C. Therefore, in Tables 2 and 3, the charge values ​​of C and N are determined based on the C of the methyl group in PDMS, and the charge values ​​of O and Si are determined based on the O in the PDMS backbone. In addition, in the latter case, the sample adsorbed with PEG contains 39% oxygen that does not originate from the PDMS backbone (refer to Table 2), thus slightly reducing the accuracy of the charge correction.

[0154] In the N 1s region, only the sample from Example 1 (PDMS rubber obtained by adsorbing PVP after plasma treatment) showed the presence of nitrogen at 399.71 eV. The peak area of ​​nitrogen was 450.5, and the peak area of ​​Si derived from PDMS was 2225. Considering the photoionization cross-sectional area ratio of nitrogen and silicon (1.8:0.817), the detected Si to N ratio was 1:0.092. As a result, the thickness of PVP can be considered to be approximately 1 nm.

[0155] In the determination of the Si 2p region of PDMS rubber before plasma treatment, the peak of Si bonded to the two methyl groups and two oxygen atoms of PDMS appeared at 101.63 eV with a full width at half maximum (FWHM) of 1.82 eV, accounting for 74.9%. The remaining 25.1% can be attributed to more oxidized Si (Figure 5). The latter can be considered as Si bonded to three O atoms, indicating that part of the PDMS chain has a branched structure via oxygen. On the other hand, in the PDMS rubber after plasma treatment, the peak of more oxidized Si (which can be considered as Si bonded to three O atoms) increased by 14.8%. This result is due to the cracking of more than 14% of the Si-CH3 bonds in PDMS, changing to Si-OH bonds, etc. (Figure 6). In contrast, as shown in Figure 7, in the sample of Example 1 (PDMS rubber obtained by adsorbing PVP after plasma treatment), the Si bonded to three O atoms increased by only 6.5% compared to the substrate. This difference (8.3%) can be understood as the oxidation being suppressed in the sample of Example 1 by PVP rebonding to silicon radicals (Si·). On the other hand, in the sample of Reference Example 1 (PDMS rubber obtained by adsorbing decane after plasma treatment), the oxidation of Si progressed more significantly, which can be understood as not rebonding to silicon radicals (Si·) (Figure 8). The sample of Example 2 (PDMS rubber obtained by adsorbing PEG after plasma treatment) was also analyzed using the same method, but the accuracy of the charge correction for this sample was lower, so it will not be discussed. On the other hand, Table 3 shows the overall full width at half maximum (FWHM) of the Si 2p peak. In the PDMS rubber before plasma treatment, this value is 2.22 eV (Figure 5), but it increases to 2.41 eV due to plasma treatment. That is, the peak broadens due to Si oxidation. However, in the sample obtained by adsorbing PVP, the peak becomes sharper, at 2.04 eV (Figure 7). On the other hand, in the case of adsorbing decane, it becomes 2.47 eV, which is approximately equal to the value after plasma treatment. This supports the view that decane is not bonded to silicon radicals (Si·). The FWHM of the PEG adsorbed case is approximately the same as that of the PVP adsorbed case, and from this result, it can be considered that PEG is bonded to silicon radicals (Si·). Accordingly, in the adsorption of hydrophilic polymers according to the method of the present invention, there is a characteristic of a smaller full width at half maximum (FWHM) of Si in the XPS measurement. Furthermore, another notable feature in Table 3 is the observation of Si atoms bonded to two O atoms at 101.63 eV in all samples. Under intense plasma irradiation conditions, the Si-C bonds of the -Si(CH3)2-O- groups in PDMS largely dissociate, and the Si atoms in PDMS are further oxidized, becoming bonded to three or four oxygen atoms. However, in Table 3, after plasma treatment of PDMS, more than 60% of the Si atoms are bonded to methyl groups. Then, in the sample of Example 1 with PVP adsorption, more than 68% of the Si atoms are bonded to two O atoms (Figure 7), and in the case of decane adsorption, more than 50% of the Si atoms are also bonded to two O atoms (Figure 8).

[0156] 2. Evaluation of the surface hydrophilicity of a substrate obtained by polymerizing PDMS containing polymerizable groups along with other (macromolecule) monomers, after plasma treatment and hydrophilization with hydrophilic polymers. In this experiment, a substrate containing polymerizable PDMS along with other macromolecular monomers and monomeric components was polymerized and subjected to plasma treatment and hydrophilic treatment with an inert gas. The surface properties of the obtained sample were then evaluated.

[0157] 2-1. Substrate modulation [Synthesis example 2] A mixture of 28 parts by weight of polydimethylsiloxane with methacrylic groups at both ends, 7 parts by weight of polydimethylsiloxane with methacrylic groups at one end, 57.9 parts by weight of trifluoromethyl acrylate, 7 parts by weight of 2-ethylhexyl acrylate, 0.1 parts by weight of dimethylaminoethyl acrylate, 0.5 parts by weight of UV absorber (RUVA-93), 0.01 parts by weight of colorant (RB246), 0.5 parts by weight of polymerization initiator (Irgacure 819), and 10 parts by weight of pentapentanol was filtered and injected between two polypropylene molds. Polymerization was then carried out by UV irradiation. After polymerization, the molds were separated, and unreacted monomers were removed by immersion in isopropanol at 60°C for 2 hours. The mixture was then washed again with isopropanol and air-dried at room temperature to obtain the substrate.

[0158] 2-2. Preparation of Lens Samples [Example 3] After plasma treatment, the substrate was immersed in a PVP aqueous solution and then coated on the substrate surface. The plasma treatment was performed using a plasma generation device with two 20cm diameter circular flat electrodes arranged parallel to each other at a 5cm interval within a chamber. The substrate was placed between the electrodes, and after vacuum substitution within the chamber, nitrogen gas was introduced, and the sample was irradiated with plasma for 30 seconds at a pressure of 19Pa. The nitrogen flow rate was set to 10sccm, and the output power was set to 50W. After plasma irradiation, nitrogen gas was introduced to restore the chamber to atmospheric pressure. The plasma-treated substrate was then immersed in a PVP aqueous solution (0.2% by mass, weight average molecular weight 1,300,000) under nitrogen conditions for 30 minutes. Then, the PVP aqueous solution containing the substrate was replaced in the air and heated at 121°C for 1 hour (sterilization). After that, it was further sterilized at 121°C for 30 minutes in the contact lens preservation solution (Softcare Pure manufactured by Seedo). After rinsing thoroughly with water to remove water adhering to the surface, it was ready for testing.

[0159] 2-3. Characteristic Evaluation 2-3-1. Assessment of hydrophilicity via water contact angle The contact angle of the sample obtained in Example 3 was measured in the order described in 1-3-1. The sample obtained in Example 3 showed superhydrophilicity, and the contact angle could not be measured.

[0160] 2-3-2. Friction Test The sample obtained in Example 3 was rubbed 20 times with a nitrile rubber glove while wetted with pure water. After washing with pure water and wiping away the water adhering to the surface, the contact angle was measured in the order described in 1-3-1. The contact angle of the sample obtained in Example 3 after the friction test was 50.1°.

[0161] 2-3-3. Evaluation of Surface Characteristics via XPS Analysis For the samples obtained in Example 3 and the substrates before and after plasma treatment, a near-atmospheric pressure X-ray photoelectron spectrometry (XPS) apparatus (Tokyo Instrument Co., Ltd., EnviroESCA, monochromatic AlKα X-rays (1486.6 eV, 42 W), passing energy (30 eV)) was used to analyze the adsorption of water molecules on the surface and the bonding mode between the substrate and the coating. Furthermore, for the plasma-treated substrate, measurements were taken one week after the plasma treatment.

[0162] In the sample obtained in Example 3, a significant water peak was identified in the O 1s region by XPS measurement at a water vapor pressure of 5 mbar. The results are shown in Figure 9. The water peak is considered to encompass both gaseous and liquid states. Furthermore, between the oxygen in the Si-O-Si bond and the oxygen in the water, there is Si-OH oxygen, but since the water peak is broader, it does not split into peaks. On the other hand, no water peaks were detected in the substrates before and after plasma treatment, but surface hydrophobicity was confirmed. The plasma-treated substrate exhibited higher hydrophilicity (water contact angle) immediately after plasma irradiation. The initial water contact angle was 19.4°, but it became hydrophobic the following day (water contact angle greater than 80°), so it can be considered that less water was adsorbed. This is because the hydrophobic PDMS diffuses from the interior to the surface.

[0163] XPS measurements at 5 mbar water vapor pressure showed that the full width at half maximum (FWHM) of the Si peak before curve fitting in the Si 2p region was 1.79 eV for the substrate before plasma treatment, while it expanded to 2.13 eV for the substrate after plasma treatment. This indicates that, as shown in the same test performed on the substrate made of PDMS rubber, the Si in PDMS is oxidized. On the other hand, in the sample obtained in Example 3, the FWHM decreased to 1.63 eV. This, also as shown in the same test performed on the substrate made of PDMS rubber, suggests that the oxidation of silicon free radicals (Si·) is suppressed due to PVP bonding.

[0164] XPS measurements at 5 mbar water vapor pressure revealed peaks originating from CF3 groups and O=CO bonds in the C1s region of both the substrates before and after plasma treatment. The XPS spectrum of the plasma-treated substrate (without PVP adsorption) is shown in Figure 10. The substrate was manufactured by polymerizing a mixture containing 57.9 parts by mass of trifluoromethyl acrylate and 28 parts by mass of polydimethylsiloxane with methacrylic groups at both ends, and can be understood as originating from these components. Furthermore, after plasma treatment, in addition to COC bonds, there was an increase in photoelectrons from HOC bonds, which can be understood as being generated by the oxidation of methyl radicals in PDMS. On the other hand, in the XPS spectrum of the C1s region of the sample obtained in Example 3, as shown in Figure 11, the peaks originating from CF3 groups or O=CO are extremely weak because the oxidation of free radicals (Si-CH2·) on the methyl group of PDMS is suppressed, and the shoulders from HOC bonds are also smaller. However, due to the mixed presence of ester and amide bonds, the peaks originating from O=CN and O=CO are broadened. Interestingly, the spectrum in Figure 11, if the weaker CF3 peak and the amplified O=CO(N) peak are excluded, is very similar to the spectrum of the sample obtained from the adsorption of PVP in PDMS rubber in Figure 3. It is presumed that this is because PVP bonds to PDMS, increasing the concentration of PDMS near the surface, which in turn originates from the partial submergence of trifluoromethyl acrylate. In other words, it can be understood that, in the same way as the substrate composed of PDMS rubber, the PDMS in the substrate becomes hydrophilic through bonding with PVP. Based on the XPS spectra of the plasma-treated substrate and the sample obtained in Example 3, the nitrogen-to-carbon ratio on the surface was calculated. It was found that the sample obtained in Example 3 contained 3.03 nitrogen atoms for every 100 carbon atoms. In the plasma-treated substrate, no X-ray photoelectrons were released near 400 eV, indicating that the PVP layer in the sample obtained in Example 3 was bonded to the substrate. Based on the XPS spectra of both, the thickness of the PVP layer in the sample obtained in Example 3 can be considered to be approximately 1 nm.

[0165] 3. Analysis of the surface condition of the substrate after plasma treatment In this experiment, the surface modification state of the substrate was analyzed during the plasma treatment stage of the prepared substrate. [Reference Example 2] 3-1. Test Methods The substrate prepared according to [Synthesis Example 2] was subjected to plasma treatment in the order described in [Example 3], and the water contact angle of the substrate surface before and after plasma treatment was measured in the order described in 1-3-1. 3-2. Experimental Results The water contact angle of the substrate surface before plasma irradiation was measured, and the results were as follows: 111°. This value is close to the contact angle of PDMS rubber (117.4°, see Table 1), and is approximately equal to the contact angle of untreated PDMS reported in the paper. Although the substrate prepared in [Synthetic Example 2] was made by polymerizing polydimethylsiloxane containing various macromolecular monomers or monomer compositions in addition to poly(methacrylamide) groups, it has this water contact angle. Therefore, it can be understood that the surface of the substrate is approximately covered with PDMS. This is because the surface tension of PDMS is 20~22 mN / m, which is significantly lower than that of other hydrocarbon polymers, so the surface covered with PDMS is thermodynamically more stable. The substrate prepared in [Synthetic Example 2] was subjected to plasma irradiation, and the water contact angle of the substrate surface was subsequently measured. The result showed that it decreased to an average of 40.7° (n=9). If the water contact angle was measured several days later, it became around 90°. After 14 days, the water contact angle increased to an average of 109.4° (n=9). That is, it roughly recovered to the initial value within 2 weeks. This variation in water contact angle demonstrates that the surface of the substrate prepared in [Synthetic Example 2] is covered with PDMS, which is activated by plasma (free radical formation), and then deactivated by exposure to the atmosphere (free radical stabilization). The internal PDMS moves to the surface and returns to its original surface state. The larger water contact angle after plasma treatment confirmed in Reference Example 1 can also be explained for the same reason.

[0166] 4. The effect of differences in oxygen content in the environment on surface hydrophilication during hydrophilication treatment in hydrophilic polymer solutions. In this experiment, we examined whether the oxygen content in the environment during the hydrophilization treatment affected the hydrophilization process.

[0167] [Examples 4 to 6] 4-1. Preparation of Lens Samples After plasma treatment, the substrate was kept in a nitrogen environment with an oxygen concentration of 0.5% by mass, 1.0% by mass, or 18.4% by mass for 3 seconds, and then immersed in a PVP aqueous solution (0.2% by mass, weight average molecular weight 40,000) in a nitrogen environment. Otherwise, the plasma treatment and hydrophilic treatment were performed in the same manner as in Example 3.

[0168] 4-2. Friction Test Friction tests were conducted on the samples obtained in Examples 4 to 6 in the order described in 2-3-2. The contact angle after friction treatment was 45.1° in the sample of Example 4, which was exposed to an oxygen concentration of 0.5% by mass for a short time after plasma treatment; 32.3° in the sample of Example 5, which was exposed to an oxygen concentration of 1.0% by mass; and 34.4° in the sample of Example 6, which was exposed to an oxygen concentration of 18.4% by mass. It has been demonstrated that by exposing the substrate to an oxygen-containing environment for a short time after plasma treatment, more hydrophilic polymers can be firmly bonded to the substrate. Specifically, the most hydrophilic polymers can be firmly bonded when exposed to an oxygen concentration of about 1.0%. This also shows that the use of Si-COO radicals is effective in enabling hydrophilic polymers to bond to the substrate more efficiently.

[0169] 5. The effect of differences in molecular weight of hydrophilic polymers on hydrophilization. In this experiment, the same hydrophilic polymers with different molecular weights were used to hydrophilize a substrate containing alkyl-containing silicates, and the effect of the difference in molecular weight of the hydrophilic polymers on the hydrophilization was examined.

[0170] [Examples 7 and 8] 5-1. Preparation of Lens Samples The plasma-treated substrate was immersed in an aqueous solution (0.2% by mass) of PVP with a weight average molecular weight of 350,000 or 40,000. Otherwise, lens samples were prepared under the same conditions and in the same order as in Example 3.

[0171] 5-2. Evaluation via friction test Friction tests were performed on the samples obtained in Examples 7 and 8, following the order described in 2-3-2. The contact angle after friction treatment was 51.5° in the sample of Example 7 (weight average molecular weight of 350,000) and 49.8° in the sample of Example 8 (weight average molecular weight of 40,000). The contact angle in the sample of Example 3 (weight average molecular weight of 1,300,000) was 50.1°, and no difference was observed in the contact angle after friction treatment due to the difference in the molecular weight of PVP.

[0172] 6. Through surface hydrophilization of different hydrophilic polymers In this experiment, the surface of the substrate was hydrophilized using different hydrophilic polymers, and the hydrophilicity was evaluated.

[0173] 6-1. Preparation of Lens Samples [Example 9] After the substrate is subjected to plasma treatment, it is immersed in an aqueous solution of polyacrylic acid and then coated on the surface of the substrate. After plasma treatment according to the conditions and sequence described in [Example 3], the sample was kept in a nitrogen environment with an oxygen concentration of 18.06% by mass for 3 seconds, and then immersed in a polyacrylic acid aqueous solution (0.2% by mass, weight average molecular weight 240,000) in a nitrogen environment for 30 minutes. Then, the polyacrylic acid aqueous solution containing the substrate was replaced in air into a vial, and heat-treated (sterilized) at 121°C for 30 minutes. The treated substrate was then placed in deionized water and further heat-treated at 121°C for 30 minutes. After heat treatment, the sample was thoroughly rinsed with water, the water adhering to the surface was wiped off, and the sample was thoroughly dried. Furthermore, sterilization with deionized water has the same effect as sterilization with contact lens preservation solution; comparative experiments confirmed that there was no significant difference in the contact angle value after the friction test. However, sterilization with deionized water may result in eye contamination when worn. Therefore, sterilization with contact lens preservation solution is more ideal for evaluating wearing performance.

[0174] [Example 10] After the substrate is subjected to plasma treatment, it is immersed in an aqueous solution of chondroitin sulfate and then coated on the surface of the substrate. After plasma treatment, nitrogen gas was introduced to restore the chamber to normal pressure. The plasma-treated substrate was then immersed in a chondroitin sulfate aqueous solution (0.1% by mass) under nitrogen environment for 30 minutes. Otherwise, plasma treatment and hydrophilic treatment were performed in the same manner as in [Example 3]. In this embodiment, chondroitin sulfate is readily soluble in water. To assess the durability of the bond with the contact lens, it was sterilized with deionized water for 1 hour. In the guidelines for sterilization methods of medical instruments (ISO / TS17665-2), the autoclave sterilization temperature is set at 121°C for at least 15 minutes. In this invention, a longer treatment time is set to confirm the surface degradation caused by heat treatment.

[0175] [Example 11] After the substrate is subjected to plasma treatment, it is immersed in an aqueous solution of hydroxyethyl cellulose and then coated on the surface of the substrate. After plasma treatment, nitrogen gas was introduced to restore the chamber to normal pressure. The plasma-treated substrate was then immersed in an aqueous solution of hydroxyethyl cellulose (0.1% by mass) under nitrogen environment for 30 minutes. Otherwise, plasma treatment and hydrophilic treatment were performed in the same manner as in [Example 3].

[0176] [Example 12] After the substrate is subjected to plasma treatment, it is immersed in an aqueous solution of ethylene glycol crosslinked polyacrylic acid and coated on the substrate surface. After plasma treatment, nitrogen gas was introduced to restore the chamber to normal pressure. Under nitrogen environment, the plasma-treated substrate was immersed in an aqueous solution (0.2% by mass) of ethylene glycol crosslinked polyacrylic acid polymer (trade name: CLPAH-100, manufactured by Fuji Film Co., Ltd.) for 30 minutes. Otherwise, plasma treatment and hydrophilic treatment were performed in the same manner as in [Example 3].

[0177] 6-2. Characteristic Evaluation (Water Contact Angle and Friction Test) Following the order described in 1-3-1 and 2-3-2, the water contact angle and friction test were performed on the samples obtained in Examples 9 to 12. The water contact angles of each sample before and after friction, together with the sample from Example 3, are summarized below. As shown in Table 4, the contact lenses modified with PVP and CLPAH-100 exhibit superhydrophilic surfaces and smaller water contact angles after the friction test. For polyacrylic acid, hydroxyethyl cellulose, and chondroitin sulfate, the contact angles after the friction test are also smaller, suggesting that by optimizing the experimental conditions, they can achieve the same performance as PVP or CLPAH-100. In the comparison of the transparency of contact lenses after drying, those modified with PV showed the best results. This may be because PVP is an amorphous polymer, retaining its transparency even after drying. On the other hand, if polyacrylic acid is adsorbed onto the contact lens and then dried, the surface tends to become slightly cloudy. Therefore, adsorption conditions such as pH must be adjusted. In the case of hydroxyethyl cellulose, there is a possibility of poor polymer dispersibility; a grade with higher dispersibility and lower ash content should be selected. Although not shown in Table 4, hyaluronic acid or alginate can also be hydrophilized in the same way as chondroitin sulfate. However, these also tend to become slightly cloudy during drying.

[0178] 6-3. Characteristic Evaluation (Evaluation of surface characteristics through XPS analysis and friction test) The sample obtained in Example 12 was rubbed 20 times with a nitrile rubber glove while wetted with pure water, washed with pure water, and the water adhering to the surface was wiped off. The resulting sample and the substrates before and after plasma treatment were analyzed under high vacuum using an X-ray photoelectron spectrometry (XPS) device (K-Alpha+, Thermo Fisher Scientific). The bonding between the substrate and the coating was analyzed using single-crystal AlKα spectrophotometry. The X-ray spot diameter was set to 400 μm. For the plasma-treated substrate, measurements were taken one week after plasma treatment. In the substrate before plasma treatment, the C:O:N:F:Si ratio was 52.8:24.2:0.2:3.7:19.3, while in the substrate after plasma treatment, it became 61.5:21.9:2.4:0.9:13.4. After plasma treatment, a small amount of nitrogen atoms were introduced into the substrate, with a presence rate of 2.4%. On the other hand, plasma treatment reduced the number of fluorine atoms from the substrate surface and increased the number of carbon atoms. It is speculated that this may be because part of the cross-linked structure of the substrate decomposes due to plasma treatment, resulting in uneven distribution of PDMS on the surface, while trifluoromethyl acrylate (TMA) sinks to the surface. In the sample obtained in Example 12 (substrate immersed in an aqueous solution of CLPAH-100), the C:O:N:F:Si ratio was 58.8:27.1:0.3:0.5:13.3. The increased presence of oxygen is due to the higher oxygen content of CLPAH-100. Furthermore, in the C1s region, the 286.4 eV component originating from CO bonds was 6.7% in the plasma-treated substrate, compared to 20.8% in the sample obtained in Example 12, a significant increase. In the sample obtained by rubbing the sample obtained in Example 12 with a rubber glove, the 286.4 eV component decreased to 8.4%, which is quite high compared to the plasma-treated substrate, indicating a significant residual of the hydrophilic polymer system. The surface of the contact lens before the friction test exhibited superhydrophilicity. That is, water droplets diffused immediately, making it impossible to measure the contact angle. Furthermore, even after the contact lens was placed in the atmosphere for 7 days following the friction test, it still showed a contact angle of 51.6°. Therefore, it is understood that the surface was coated with a hydrophilic polymer.

[0179] 7. The effect of differences in the composition of (macromolecule) monomers used to make the substrate on hydrophilicity. In this experiment, the effect of varying the composition of the (macromolecule) monomers used to make the substrate on the hydrophilicity of the substrate was examined.

[0180] 7-1. Substrate Modulation [Synthesis example 3] The content of trifluoromethyl acrylate was set to 38.6 parts by mass. As the content was reduced, the amount of 2-ethylhexyl acrylate was increased. Otherwise, the substrate was obtained under the same conditions and in the same order as in Synthesis Example 2.

[0181] [Synthesis Example 4] The content of trifluoromethyl acrylate was set to 19.3 parts by mass. As the content was reduced, the amount of 2-ethylhexyl acrylate was increased. Otherwise, the substrate was obtained under the same conditions and in the same order as in Synthesis Example 2. 7-2. Plasma Treatment and Coating [Examples 13 and 14] Using the substrates of Synthetic Examples 3 and 4, plasma treatment and hydrophilic treatment were performed in accordance with the conditions and order described in [Example 12].

[0182] 7-3. Characteristic Evaluation (Contact Angle and Friction Test) In accordance with the order described in 1-3-1 and 2-3-2, contact angle measurements and friction tests were performed on the substrate before plasma treatment and the samples obtained in Examples 13 and 14. The results are summarized below. Before the friction treatment, the water contact angle was superhydrophilic in all samples from Examples 12 to 14. Variations in the content of monomers other than alkyl-containing silicates did not significantly affect the bonding of the hydrophilic polymers, which can be understood as the hydrocarbon-containing polysiloxanes participating in the bonding of the hydrophilic polymers to the substrate. On the other hand, the contact angle after the friction treatment tended to increase as the content of trifluoromethyl acrylate decreased. This can be attributed to the fact that the substrate with a lower content of this monomer is very soft, resulting in increased deformation when rubbed with a rubber glove, making CLPAH-100 easier to peel off (or, because PDMS is easily exposed to the surface). It can be said that the mechanical strength of the contact lens has some influence on the stability of the hydrophilic coating.

[0183] 8. Review of different plasma generation methods and the hydrophilization of different hydrophilic polymers In this experiment, plasma was generated by glow discharge, and different hydrophilic polymers were used to hydrophilize the substrate surface to evaluate the hydrophilicity.

[0184] 8-1. Preparation of Lens Samples [Example 15] Using a plasma generation device (manufactured by Meiwafosis, trade name: SEDE (soft etching device)) with a 9cm diameter glow discharge type parallel plate electrode (electrode spacing: 4cm), nitrogen gas was introduced through a needle valve, and plasma was generated at a pressure of 20Pa and a current of 15mA. The substrate prepared according to [Synthesis Example 2] was irradiated for 10 seconds. After plasma irradiation, nitrogen was introduced and the chamber was restored to atmospheric pressure. The substrate was immersed in a 1.0% (w / w) aqueous solution of polyvinyl alcohol with a molecular weight of 25,000 in a nitrogen environment with an oxygen concentration of 0.2% for 1 hour. After rinsing with water, the substrate was placed in a contact lens preservation solution (manufactured by Seedo, Softcare Pure) and further heated at 121°C for 30 minutes. After the heat treatment, the sample was thoroughly rinsed with water to remove water adhering to the surface.

[0185] [Example 16] The plasma-treated substrate was immersed in an aqueous solution (1.0% by mass) of Pluronic F-127 (a block copolymer containing PEG, a surfactant) in a nitrogen environment with an oxygen concentration of 0.6%. Otherwise, a lens sample was prepared by hydrophilizing the surface in the same manner as in Example 15.

[0186] [Example 17] The plasma-treated substrate was immersed in a PEG aqueous solution (1.0% by mass) with a molecular weight of 1,000 in a nitrogen environment with an oxygen concentration of 0.6%. Otherwise, lens samples were prepared by hydrophilizing the surface in the same manner as in Example 15. In addition, in Examples 15 to 17, a simple glove bag made of polyolefin was used for nitrogen substitution, so the oxygen concentration measured by the oxygen concentration meter will vary slightly due to the deterioration of the glove bag.

[0187] 8-2. Characteristic Evaluation (Water Contact Angle and Friction Test) Contact angle analysis and friction tests were performed on the samples obtained in Examples 15 to 17, following the order described in 1-3-1 and 2-3-2. However, for the samples obtained in Examples 16 and 17, the friction tests were performed 10 times. The test results are summarized below. As shown in Table 6, it is understood that plasma obtained through glow discharge can also adsorb hydrophilic polymers, such as polyvinyl alcohol, Pluronic F-127, and PEG, which are all hydrophilized. Furthermore, in at least 10 rubbing tests, the water contact angle did not decrease significantly, falling below 70°. However, compared to low-frequency plasma, the plasma obtained through glow discharge is less stable and stronger. Therefore, setting the plasma irradiation time to one-third (10 seconds) is shorter than the former, making it difficult to control. Specifically, in the case of glow discharge, the plasma is not stable in the first 0.5 seconds. Furthermore, because electrons flow in a certain direction, deviations easily occur on the surface and interior of the contact lens. Therefore, when using glow discharge for surface modification of contact lenses, it is necessary to develop a method for transporting the contact lens into the plasma.

[0188] 9. Review of plasma generation conditions In this experiment, plasma was generated under different conditions to examine its effect on hydrophilization.

[0189] [Example 18] 9-1. Preparation of Lens Samples The plasma treatment system used a plasma generation device (manufactured by Kuei Semiconductor Co., Ltd., trade name: YHS-DC100) with two 10cm diameter circular flat electrodes arranged parallel to each other at a 5cm interval within a chamber. The substrate prepared according to [Synthesis Example 2] was placed between the electrodes. After vacuum substitution within the chamber, nitrogen gas was introduced, and the sample was irradiated with plasma at a pressure of 20 Pa for 30 seconds. The nitrogen flow rate was set to 10 sccm, and the output power was set to 50 W. After plasma irradiation, nitrogen gas was introduced to restore the chamber to atmospheric pressure. The plasma-treated substrate was then immersed in a 0.3% (w / w) CLPAH-100 aqueous solution under nitrogen conditions for 30 minutes. Then, the CLPAH-100 aqueous solution containing the contact lens was transferred to a vial in air and heated at 121°C for 30 minutes. After thorough rinsing with water, the substrate was placed in a contact lens preservation solution (manufactured by Seedo, Softcare Pure) and further heated at 121°C for 30 minutes. After heat treatment, the sample is thoroughly rinsed with water to remove the water adhering to the surface.

[0190] 9-2. Characteristic Evaluation (Contact Angle and Friction Test) Following the order described in 1-3-1 and 2-3-2, the contact angle and friction test were performed on the obtained sample. The sample obtained in Example 18 was superhydrophilic (water contact angle could not be measured), and the contact angle after friction treatment was 58.3°. In addition, a water contact angle of 70.5° was also observed 4 days after the friction test.

[0191] 10. Review of gas flow rate during plasma processing In this experiment, the effect of differences in nitrogen flow rate during plasma treatment on the activation of the substrate surface was evaluated. [Refer to Examples 3 and 4] 10-1. Plasma Treatment The nitrogen flow rate was increased to 20 sccm or 30 sccm. Otherwise, plasma treatment was performed only on the substrate prepared in [Synthesis Example 2] in the order and conditions described in [Example 3]. 10-2. Evaluation of substrate surface activation (water contact angle) The water contact angles of the substrates in Reference Examples 3 and 4 were measured in the order described in 1-3-1. The water contact angle of the substrate in Reference Example 2, obtained by plasma treatment with a nitrogen flow rate of 10 sccm, was 40.7°. In contrast, the water contact angles of the substrates in Reference Examples 3 and 4, obtained by setting nitrogen flow rates of 20 sccm and 30 sccm, were increased to 46.6° and 63.1°, respectively. This suggests that increasing the nitrogen flow rate leads to a decrease in the activation of the substrate surface, i.e., the number of free radicals. This can be attributed to the fact that as the amount of nitrogen flowing in increases, the concentration of active species in the nitrogen plasma decreases. Simultaneously, if the gas flow rate is large, the gas temperature also decreases, making the plasma more tolerant. Since hydrophilicity can be enhanced by increasing the plasma irradiation time, it is ideal to set a longer irradiation time when increasing the gas flow rate.

[0192] 11. Review of the chamber environment in plasma processing (1) In this experiment, plasma was generated in a CO2 gas environment to examine its effect on hydrophilization.

[0193] [Comparative Example 1] 11-1. Preparation of Lens Samples The environment inside the chamber was set to CO2 gas instead of nitrogen gas. Otherwise, the lens sample was prepared in the same manner as in Example 18. Between the electrodes of the plasma generation apparatus used in Example 18, a substrate prepared according to Synthesis Example 2 was placed. After vacuum substitution in the chamber, CO2 gas was introduced and the sample was irradiated with plasma for 30 seconds at a pressure of 20 Pa. The flow rate of CO2 gas was set to 10 sccm, and the output power was set to 50 W. After plasma irradiation, CO2 gas was introduced to restore the chamber to atmospheric pressure. The plasma-treated substrate was then immersed in a CLPAH-100 aqueous solution (0.3% by mass) for 30 minutes. After rinsing with water, the CLPAH-100 aqueous solution containing the contact lens was replaced in air and heated at 121°C for 30 minutes. After thorough rinsing with water, the sample was placed in a contact lens preservation solution (Softcare Pure, manufactured by Seedo) and further heated at 121°C for 30 minutes. After the heating treatment, the sample was thoroughly rinsed with water to remove water adhering to the surface.

[0194] 11-2. Characteristic Evaluation (Water Contact Angle and Friction Test) Following the order described in 1-3-1 and 2-3-2, the water contact angle and friction test were performed on a plurality of samples (n=6). Table 7 shows the changes in water contact angles on the surfaces of the six samples in Comparative Example 1. When using N2 plasma, the contact angle after washing became superhydrophilic, but the deviation was larger due to the CO2 plasma. After the friction test, the deviation was smaller, confirming the bonding of CLPAH-100. However, the water contact angle after 4 days of exposure to the atmosphere showed 91.6°, indicating that CLPAH-100 is prone to peeling.

[0195] 12. Review of the chamber environment in plasma processing (2) In this experiment, plasma was generated in an air environment to examine its effect on hydrophilization.

[0196] [Comparative Example 2] 12-1. Preparation of Lens Samples The environment inside the chamber was set to air (oxygen concentration: 21%) instead of nitrogen. Otherwise, the lens sample was prepared in the same manner as in Example 18. Between the electrodes of the plasma generation apparatus used in Example 18, a substrate prepared according to Synthesis Example 2 was placed. After vacuum substitution in the chamber, air (oxygen concentration: 21%) was introduced from the outside gas, and the sample was irradiated with plasma for 30 seconds at a pressure of 20 Pa. The air flow rate was set to 30 sccm (taken from the atmosphere), and the output power was set to 50 W. After plasma irradiation, air was introduced to restore the chamber to normal pressure. The plasma-treated substrate was immersed in a CLPAH-100 aqueous solution (0.3% by mass) in air for 30 minutes. After rinsing with water, the CLPAH-100 aqueous solution containing the contact lens was replaced in air into a vial and heated at 121°C for 30 minutes. After thorough rinsing with water, the sample was placed in a contact lens preservation solution (Softcare Pure, manufactured by Seedo Corporation) and further heated at 121°C for 30 minutes. After the heating treatment, the sample was thoroughly rinsed with water to remove water adhering to the surface.

[0197] 12-2. Characteristic Evaluation (Water Contact Angle and Friction Test) Following the order described in 1-3-1 and 2-3-2, the water contact angle and friction test were performed on a plurality of samples (n=6) obtained in Comparative Example 2. Table 8 shows the changes in water contact angles on the surfaces of the six samples in Comparative Example 2. The contact angles after washing became superhydrophilic. After the friction test, the deviation was small, confirming the bonding of CLPAH-100. However, the water contact angles after 4 days of exposure to the atmosphere showed 93.1° or 94.6°, suggesting that CLPAH-100 was more easily peeled off compared to the CO2 plasma. In fact, the average water contact angle after 4 days was 89.9°, which was 5.2° larger than the CO2 plasma case. This may be due to the reduction of Si· or Si-CH2· radicals on the contact lens surface caused by oxygen in the air plasma. Although there is a possibility of the formation of functional groups such as hydroxyl groups on some parts of the surface, these functional groups are believed to disappear from the contact lens surface over time and undergo hydrophobication.

[0198] 13. Evaluation of hydrophilicity via plasma polymerization Patent document 9 proposes a method for forming a polymer film on the surface of a contact lens containing PDMS by plasma polymerization of hydrogen and tetrafluoroethylene, and further hydrophilicating the surface by oxygen plasma treatment. In addition, patent document 10 proposes a method for forming a hydrophilic coating by plasma polymerization using a mixed gas of argon and N-vinylpyrrolidone. Therefore, in this experiment, the hydrophilicity of the lens obtained by forming a hydrophilic coating through plasma polymerization was evaluated and compared with that of the lens obtained by the plasma treatment method of the present invention.

[0199] [Comparative Example 3] 13-1. Preparation of Lens Samples A plasma generating device (manufactured by Kuei Semiconductor Co., Ltd., trade name: YHS-DC100) using two 10cm diameter circular flat electrodes arranged parallel to each other at a 5cm interval within a plasma generating chamber was used. The substrate prepared according to [Synthesis Example 2] was placed between the electrodes. N-vinylpyrrolidone vapor was introduced into the plasma generating device chamber from a glass container already filled with liquid N-vinylpyrrolidone. At this time, the inner diameter of the plasma chamber was set to 120mm, and the inner diameter of the vapor inlet pipe was set to 4mm. The pressure of the N-vinylpyrrolidone within the chamber was increased by tightening the exhaust flow path. With the exhaust flow path open, the flow rate of N-vinylpyrrolidone cannot exceed 12 sccm, and the pressure inside the chamber becomes 2 Pa, thus preventing the generation of N-vinylpyrrolidone plasma. This can be attributed to the larger molecular weight of N-vinylpyrrolidone, resulting in fewer free radicals being generated. On the other hand, if the exhaust flow path is completely closed, a vapor pressure of approximately 18 Pa can be achieved. In this case, the pressure inside the chamber increases to approximately 40 Pa due to plasma generation. This can be attributed to the decomposition of N-vinylpyrrolidone in the plasma, with the number of decomposition product molecules at least doubling. Therefore, the exhaust flow path is slightly opened, reducing the pressure inside the chamber to 10 Pa. In this case, the inflow rate of N-vinylpyrrolidone vapor is approximately 0 sccm. The output power is set to 50 W, plasma is generated, and the substrate is irradiated with the plasma for 30 seconds. Then, air is introduced, and the chamber is restored to atmospheric pressure. The obtained sample is thoroughly rinsed with water to remove water adhering to the surface. If the obtained sample is rinsed with water, it will turn slightly white, but if rubbed, it will immediately peel off and become transparent. This is believed to be due to the formation of a carbon film on the surface, which peels off when rubbed.

[0200] 13-2. Characteristic Evaluation (Water Contact Angle and Friction Resistance) Following the order described in 1-3-1 and 2-3-2, water contact angle and friction tests were performed on a plurality of samples (n=6) obtained in Comparative Example 3. The results are shown below. Table 9 shows the changes in water contact angles on the surfaces of the six samples in Comparative Example 3. The contact angles after washing did not become superhydrophilic, suggesting the formation of a carbon film. This carbon film was largely peeled off by friction testing, but the water contact angles remained stable. However, in measurements of the water contact angles after four days of exposure to the atmosphere, all showed values ​​above 100°. This indicates that the carbon film did not substantially cover the surface of the contact lens and peeled off and became significantly hydrophobic over time. Furthermore, this result shows that no PVP film formed on the surface of the contact lens. In plasma polymerization using N-vinylpyrrolidone as a gaseous feedstock, introducing vapor into the chamber is not only difficult, but N-vinylpyrrolidone also decomposes within the plasma to form a carbon film, which is easily peeled off due to frictional stress. In other words, a carbon film is formed that is completely different from the hydrophilic polymer coating of this invention and is easily peeled off.

[0201] 14. Durability under friction testing and storage in the atmosphere In this test, the durability under repeated friction tests and exposure to the atmosphere was evaluated.

[0202] [Example 19] 14-1. Preparation of Lens Samples After plasma treatment, the substrate was immersed in a PVP aqueous solution and coated onto its surface. The plasma treatment was performed using a plasma generation device with two 20cm diameter circular flat electrodes arranged parallel to each other at a 5cm interval within a chamber. The substrate prepared according to [Synthesis Example 2] was placed between the electrodes. After vacuum substitution within the chamber, nitrogen gas was introduced, and the sample was irradiated with plasma at a pressure of 19Pa for 60 seconds. The nitrogen flow rate was set to 10 sccm, and the output power was set to 80W. After plasma irradiation, nitrogen gas was introduced to restore the chamber to atmospheric pressure. The plasma-treated substrate was then immersed in a PVP aqueous solution (0.2% by mass, weight average molecular weight 360,000) under nitrogen conditions for 30 minutes. The sample was then thoroughly rinsed with water to remove surface water.

[0203] 14-2. Characteristic Evaluation (Contact Angle and Friction Test) 14-2-1. Friction Test The sample (n=3) obtained in Example 19 was rubbed 200 times with a nitrile rubber glove while wet with pure water. After washing with pure water and wiping away the water adhering to the surface, the water contact angle was measured in the order described in 1-3-1. 14-2-2. Hydrophilicity assessment after 3 days of exposure to the atmosphere To evaluate the stability of the hydrophilic polymer coating on the surface, the sample (n=3) obtained in Example 19 was rubbed 200 times with a nitrile rubber glove while wet with pure water, washed with pure water, and the water adhering to the surface was wiped off. The sample was then exposed to the atmosphere for 3 days, and the contact angle was measured in the order described in 1-3-1. 14-2-3. Evaluation of hydrophilicity after water treatment To assess the recovery of hydrophilicity reduction after exposure testing, the samples (n=3) exposed to the atmosphere for 3 days were immersed in water for 10 minutes. After wiping away the water adhering to the surface, the contact angle was measured in the order described in 1-3-1.

[0204] The results of each experiment are shown below. []

[0205] The average contact angle of the sample obtained in Example 19 after 200 friction tests was 42.1°. This result demonstrates that the sample of Example 19 maintained sufficient hydrophilicity even after 200 friction tests. The average contact angle of the sample obtained in Example 19 after exposure to the atmosphere for 3 days was 61.1°. Furthermore, the average contact angle of the sample obtained in Example 19 after 10 minutes of water treatment was 57.4°. These results indicate that even after 200 friction tests followed by exposure to the atmosphere, the surface hydrophilic polymer remained intact, and the hydrophilicity was partially restored by immersion in water. In this embodiment, plasma treatment is performed by irradiating the sample with plasma for 60 seconds and setting the output power to 80W. This generates more free radicals near the surface, which can be considered as causing a reaction that strengthens the bond between the hydrophilic polymer and the substrate and inhibits the diffusion of hydrophobic polymers on the surface. Furthermore, the entanglement of the hydrophilic polymer with the PDMS chains makes the hydrophilic polymer on the surface less prone to peeling off. That is, the Si· free radicals formed near the sample surface eventually form Si-OH groups (silanol groups). These silanol groups undergo dehydration condensation, introducing a cross-linked structure into the PDMS chains. It can be considered that when the silanol groups formed on the surface undergo dehydration condensation, if hydrophilic polymers are present nearby, the hydrophilic polymers will become entangled with the cross-linked PDMS chains, thereby making the hydrophilic polymers less prone to peeling off (refer to Figure 1 above).

[0206] 15. Durability under friction testing and long-term storage in the atmosphere. In this test, the durability under repeated friction tests and long-term exposure to the atmosphere was evaluated. [Example 20] 15-1. Preparation of Lens Samples After plasma treatment, the substrate was immersed in a PVP aqueous solution and coated onto its surface. The plasma treatment was performed using a plasma generation device with two 20cm diameter circular flat electrodes arranged parallel to each other at a 5cm interval within a chamber. The substrate prepared according to [Synthesis Example 2] was placed between the electrodes. After vacuum substitution within the chamber, nitrogen gas was introduced, and the sample was irradiated with plasma at a pressure of 19Pa for 60 seconds. The nitrogen flow rate was set to 10sccm, and the output power was set to 80W. After plasma irradiation, nitrogen gas was introduced to restore the chamber to atmospheric pressure. The plasma-treated substrate was then immersed in a PVP aqueous solution (0.2% by mass, weight average molecular weight 360,000) under nitrogen conditions for 30 minutes. Then, in air, the contact lens was replaced into a vial containing a 1.0% by weight aqueous solution of polyphosphatidylcholine (MPC: poly-2-methacryloxyethylphosphatidylcholine, weight average molecular weight 100,000), and heated at 121°C for 30 minutes. After heat treatment, the sample was thoroughly rinsed with water to remove water adhering to the surface.

[0207] 15-2. Characteristic Evaluation (Contact Angle and Friction Test) 15-2-1. Friction Test The sample (n=6) obtained in Example 20 was rubbed 200 times with a nitrile rubber glove while wet with pure water. After washing with pure water and wiping away the water adhering to the surface, the water contact angle was measured in the order described in 1-3-1. 15-2-2. Hydrophilicity assessment after 3 days of exposure to the atmosphere To evaluate the stability of the hydrophilic polymer coating on the surface, the sample (n=6) obtained in Example 20 was rubbed 200 times with a nitrile rubber glove while wet with pure water, washed with pure water, and the water adhering to the surface was wiped off. The sample was then exposed to the atmosphere for 6 days, and the contact angle was measured in the order described in 1-3-1. 15-2-3. Evaluation of hydrophilicity after water treatment [] To assess the recovery of hydrophilicity reduction after exposure testing, the samples (n=6) exposed to the atmosphere for 6 days were immersed in water for 10 minutes. After wiping away the water adhering to the surface, the contact angle was measured in the order described in 1-3-1. The results of each experiment are shown below. The average contact angle of the sample obtained in Example 20 after 200 friction tests was 45.5°. This result demonstrates that the sample of Example 20 maintained sufficient hydrophilicity even after 200 friction tests. Furthermore, the sample obtained after further exposure to the atmosphere for 6 days following the friction treatment had an average contact angle of 54.5°. Additionally, the sample obtained after further immersion in water for 10 minutes following exposure to the atmosphere had an average contact angle of 49.8°. It can be considered that the sample of this example maintained its surface hydrophilic polymer even after prolonged exposure to the atmosphere following the friction test.

Claims

1. A soft ophthalmic lens comprising an ophthalmic lens substrate comprising an ophthalmic lens substrate having an alkyl-containing polysiloxane structure, and a single coating on the surface of the substrate comprising a hydrophilic polymer, wherein the hydrophilic polymer comprises a structure capable of resonating with free radicals on carbon atoms, the substrate and the hydrophilic polymer are bonded at least via C-C bonds between the Si-C of the substrate and the C of the hydrophilic polymer, and the water contact angle of the coating surface is 70° or less.

2. The soft ophthalmic lens as claimed in claim 1, wherein, The full width at half maximum (FWHM) of the Si2p peak, as measured by XPS, is less than 2.1 eV.

3. The soft ophthalmic lens as claimed in claim 1, wherein, As determined by XPS, more than 60% of the peaks originating from Si2p are bonded to two O atoms and two C atoms.

4. The soft ophthalmic lens as described in claim 1, wherein, Surface-adsorbed water was confirmed by XPS measurements at a water vapor pressure of 5 mbar.

5. The soft ophthalmic lens as described in claim 4, wherein, The water contact angle of the aforementioned coating surface was below 70° after 20 friction tests.

6. The soft ophthalmic lens as claimed in claim 4, wherein, The water contact angle of the aforementioned coating surface was less than 50° after 200 friction tests.

7. The soft ophthalmic lens as claimed in claim 1, wherein, The aforementioned coating has a thickness of 1 nm to 5 μm.

8. The soft ophthalmic lens as claimed in claim 1, wherein, The aforementioned substrate and the aforementioned hydrophilic polymer are further bonded via an OC bond between the Si-alkyl-OO of the substrate and the C of the hydrophilic polymer.

9. The soft ophthalmic lens as claimed in claim 1, wherein, The aforementioned substrate and the aforementioned hydrophilic polymer system are further bonded via Si-C bonds between the Si of the substrate and the C of the hydrophilic polymer.

10. The soft ophthalmic lens as claimed in claim 1, wherein, The aforementioned hydrophilic polymer is water-soluble and has atoms or double bonds with non-covalent bond pairs. The carbon system adjacent to the atoms or double bonds with non-covalent bond pairs is bonded to the carbon of Si, Si-C or oxygen of Si-alkyl-OO in the aforementioned substrate.

11. The soft ophthalmic lens of claim 1, wherein, The aforementioned substrate is obtained by polymerizing a (macromolecule) monomer composition containing more than 20% by mass of alkyl-containing polysiloxanes.

12. The soft ophthalmic lens as claimed in claim 10, wherein, The aforementioned hydrophilic polymers include polyvinylpyrrolidone, polyacrylic acid, ethylene glycol crosslinked polyacrylic acid, polyacrylic acid starch grafts, PEG, block copolymers containing PEG, alginate, chondroitin sulfate, hyaluronic acid, pectin, hydroxyethyl cellulose, dextran, polyvinyl alcohol, polyethyleneimine, polyglutamic acid, or polyacrylamide.

13. The soft ophthalmic lens of claim 1 has an oxygen permeability Dk value of 150 or higher.

14. A method for manufacturing a soft ophthalmic lens, comprising having a single coating of a hydrophilic polymer on an ophthalmic lens substrate comprising a (co)polymer having an alkyl-containing polysiloxane structure, the method comprising: subjecting the substrate to plasma treatment in an inert gas environment to form free radicals comprising at least Si-alkyl free radicals on the surface of the substrate; and immersing the substrate, while maintaining the aforementioned free radicals comprising Si-alkyl free radicals, in an aqueous solution of a hydrophilic polymer comprising a structure capable of resonance when free radicals are formed on carbon atoms, thereby performing free radical transfer to the hydrophilic polymer and bonding the hydrophilic polymer to the substrate through the free radicals generated by the hydrophilic polymer, thereby forming a coating comprising the hydrophilic polymer.

15. As in request item 14, wherein, The aforementioned free radicals include Si-free radicals and Si-alkyl-free radicals.

16. As in request item 15, wherein, The aforementioned free radicals further include Si-enylalkyl-OO・free radicals.

17. As in request item 14, wherein, Immediately following the aforementioned plasma treatment, at least 10% of the C in the Si bonds present on the surface of the aforementioned substrate becomes free radicals.

18. As in request item 14, wherein, Immediately following the aforementioned plasma treatment, at least 20% of the alkyl-containing polysiloxane units present on the surface of the aforementioned substrate become free radicals.

19. As in request item 14, wherein, The aforementioned plasma is generated at a low frequency of 50Hz or 60kHz and a power of 10 to 150W.

20. As in request item 19, wherein, The aforementioned inert gas is introduced into the reaction chamber at a pressure of 2 Pa to 30 Pa and a speed of 1 sccm to 100 sccm.

21. The method as described in request item 19, wherein, Perform the aforementioned plasma treatment for 5 seconds to 2 minutes.

22. As in request item 21, wherein, The aforementioned plasma is generated at a power of 60 to 150W, and the aforementioned plasma treatment is performed for 50 seconds to 2 minutes.

23. As in request item 14, wherein, The aforementioned plasma is generated at 3–30 mA via glow discharge.

24. As in request item 14, wherein, The aforementioned substrate is obtained by polymerizing a (macromolecule) monomer composition containing more than 20% by mass of alkyl-containing polysiloxanes.

25. As in request item 14, wherein, The aforementioned hydrophilic polymer is water-soluble and has alkyl, alkylene, or methine groups, as well as atoms or double bonds with non-shared electron pairs. The carbon groups of the aforementioned alkyl, alkylene, or methine groups are adjacent to the aforementioned atoms or double bonds with non-shared electron pairs.

26. As in request item 25, wherein, The aforementioned hydrophilic polymers include polyvinylpyrrolidone, polyacrylic acid, ethylene glycol crosslinked polyacrylic acid, polyacrylic acid starch grafts, PEG, block copolymers containing PEG, alginate, chondroitin sulfate, hyaluronic acid, pectin, hydroxyethyl cellulose, dextran, polyvinyl alcohol, polyethyleneimine, polyglutamic acid, or polyacrylamide.

27. As in request item 14, wherein, The substrate that has undergone the aforementioned plasma treatment will be kept in an oxygen-containing environment for a short period of time.

28. As in request item 14, wherein, The substrate with the aforementioned free radicals formed is immersed in the aforementioned aqueous solution of hydrophilic polymer within 10 seconds after the aforementioned plasma treatment.

29. As in request item 14, wherein, The substrate with the aforementioned free radicals formed is immersed in an aqueous solution of the aforementioned hydrophilic polymer at a temperature of 10–30°C for 30 minutes to 1 hour.

30. The method as described in request item 29, wherein, The substrate with the aforementioned free radicals formed is further immersed in an aqueous solution of the aforementioned hydrophilic polymer at a temperature of 80–135°C for 20 minutes to 2 hours, and then subjected to heat treatment.

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