Polythiol, polymerizable composition for optical material, optical material, and method for producing same

Abstract

The present invention provides a polythiol obtained by thiolating a hydroxyl group of a plant-derived polyol.

Description

Technical Field

[0001] This invention relates to polythiols, polymeric compositions for optical materials, optical materials, and methods for manufacturing the same. Background Technology

[0002] Patent Document 1 discloses a polymeric composition for optical materials containing polyisocyanates, polyols derived from plant sources, etc.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 6571968 Specification Summary of the Invention

[0006] Problems to be solved by the invention

[0007] From the perspective of effectively utilizing non-fossil resources, it is desirable to use plant-derived raw materials to manufacture optical materials. However, according to the inventors' research, optical materials manufactured from polymeric compositions of optical materials disclosed in Patent Document 1 have high haze, and further improvements are required in terms of optical properties.

[0008] One aspect of this invention aims to provide plant-derived compounds suitable for producing optical materials with excellent optical properties.

[0009] Problem Solving Methods

[0010] Through repeated and in-depth research, the inventors have made a new discovery: by converting the hydroxyl (OH) groups of plant-derived polyols into thiohydroxyl (SH) polythiols, low-haze optical materials can be manufactured.

[0011] That is, one aspect of the present invention is as follows.

[0012] [1] A polythiol obtained by thiolation of the hydroxyl groups of a plant-derived polyol.

[0013] [2] According to the polythiol described in [1], wherein,

[0014] The plant-derived polyols mentioned above are glycerol, sorbitol, isosorbide, sucrose, α-methyl glycoside, mannitol, 1,4-butanediol, 1,3-butanediol, or 1,3-propanediol.

[0015] [3] A polymeric composition for optical materials comprising one or more polythiols as described in [1] or [2], and one or more polyisocyanates.

[0016] [4] The polymeric composition for optical materials according to [3] further comprises plant-derived polyols.

[0017] [5] An optical material, which is a cured product formed by curing the optical material described in [3] with a polymeric composition.

[0018] [6] The optical material described in [5] is a lens.

[0019] [7] The optical material described in [6] is an eyeglass lens.

[0020] [8] An optical material, which is a cured product formed by curing the optical material described in [4] with a polymeric composition.

[0021] [9] The optical material described in [8] is a lens.

[0022]

[10] The optical material described in [9] is an eyeglass lens.

[0023]

[11] A method for producing polythiols, comprising:

[0024] Thiolization of the hydroxyl groups of plant-derived polyols.

[0025]

[12] A method for manufacturing a polymeric composition for optical materials, comprising:

[0026] Polythiols are manufactured using the manufacturing method described in

[11] , and

[0027] The manufactured polythiols are mixed with one or more polyisocyanates.

[0028]

[13] A method for manufacturing an optical material, comprising:

[0029] The manufacturing method described in

[12] produces polymeric compositions for optical materials, and

[0030] The manufactured optical material is cured by using a polymeric composition to obtain a cured product.

[0031]

[14] According to the method for manufacturing optical materials described in

[13] , wherein,

[0032] The optical material is a lens.

[0033]

[15] According to the method for manufacturing optical materials described in

[14] , wherein,

[0034] The lens mentioned above is a spectacle lens.

[0035] The effects of the invention

[0036] According to one aspect of the present invention, plant-derived compounds suitable for producing optical materials with excellent optical properties can be provided. Detailed Implementation

[0037] [Polythiols and their manufacturing methods]

[0038] One aspect of the present invention relates to a polythiol obtained by thiolation of the hydroxyl groups of a plant-derived polyol.

[0039] In addition, one aspect of the present invention relates to a method for producing polythiols, which includes thiolation of the hydroxyl groups of a plant-derived polyol.

[0040] In this invention and specification, "plant-derived polyols" refers to polyols obtained from plants through one or more stages of processing. Examples of such processes include fermentation, extraction, separation, and reaction. Polyols contain carbon. 14 The "C" indicates that the polyol is of plant origin. Plant origin can be detected by measuring the carbon content using a standard based on ASTM D6866 Method B. 14 C is used for confirmation. The same applies to the "plant source" of the various compounds described below. In contrast, "non-plant source" as mentioned later refers to those obtained from raw materials other than plants, and "petroleum source" refers to those obtained from petroleum raw materials.

[0041] Plant-derived polyols can be obtained by known methods. The thiolation of the hydroxyl groups (OH) of plant-derived polyols can be carried out by any of the following methods (1) to (4), for example.

[0042] (1) Hydrogen halides (such as hydrobromic acid HBr, hydrochloric acid HCl, etc.) and thiourea react with polyols to form isothiourea salts, and then the isothiourea salts are hydrolyzed.

[0043] (2) After reacting hydrogen halide (e.g., hydrobromic acid HBr) with polyol to obtain a halide (e.g., bromide), react with sulfides such as sodium sulfide, sodium hydrosulfide, potassium sulfide, and hydrogen sulfide.

[0044] (3) Hydrogen sulfide and polyols are reacted under high temperature and high pressure in the presence of a catalyst.

[0045] (4) Reaction of methanesulfonyl chloride with a polyol yields a sulfonate (ester). Alternatively, reaction of toluenesulfonyl chloride or acetic anhydride with a polyol yields a toluenesulfonate or ester. The thioester obtained by reacting the product thus obtained with a thioacetate (e.g., potassium thioacetate) is then reduced using a reducing agent (e.g., LiAlH4). Alternatively, an acid (e.g., HCl) may be added instead of a reducing agent to carry out hydrolysis.

[0046] Plant-derived polyols that convert hydroxyl groups to thiohydroxyl groups through thiolation can be, for example, polyols with more than two functions and less than ten functions. The functionality number of a polyol refers to the number of hydroxyl groups contained in one molecule of the polyol. Polythiols obtained by thiolation of the hydroxyl groups of plant-derived polyols include cases where all hydroxyl groups of the plant-derived polyol have undergone thiolation, as well as cases where some hydroxyl groups remain. Specific examples of plant-derived polyols include glycerol, sorbitol, isosorbide, sucrose, α-methyl glycosides, mannitol, 1,4-butanediol, 1,3-butanediol, and 1,3-propanediol.

[0047] The biomass ratio, as an indicator related to plant-derived raw materials, can be determined based on the standard ASTM D6866 METHOD B and calculated using the following formula. For example, the biomass ratio of polythiols obtained by thiolation of the hydroxyl groups of plant-derived polyols can be 100%.

[0048] Biomass ratio = (Number of carbon atoms from plant sources / (Number of carbon atoms from plant sources + Number of carbon atoms from non-plant sources)) × 100

[0049] [Polymeric compositions for optical materials and methods for their manufacture]

[0050] One aspect of the present invention relates to a polymeric composition for optical materials comprising: one or more polythiols obtained by thiolation of the hydroxyl groups of a plant-derived polyol, and one or more polyisocyanates.

[0051] Additionally, one aspect of the present invention relates to a method for manufacturing a polymeric composition for optical materials, comprising: manufacturing a polythiol by the above-described manufacturing method, and mixing the manufactured polythiol with one or more polyisocyanates. One or more polythiols manufactured by the above-described manufacturing method may be mixed with one or more polyisocyanates.

[0052] Based on the above-mentioned polymerizable composition for optical materials, polythiourethane optical materials can be manufactured by reacting polythiols with polyisocyanates.

[0053] In this invention and specification, the term "polyisocyanate" is used to encompass both polyisocyanate and polyisothiocyanate. It should be noted that isocyanate is sometimes also called isocyanato, and isothiocyanate is sometimes also called isothiocyanato. Furthermore, the term "isocyanate group" is used to encompass both isocyanate group (-N=C=O) and isothiocyanate group (-N=C=S). "Polyisocyanate" refers to a polyfunctional compound having two or more isocyanate groups in one molecule. By reacting a polythiol with a polyisocyanate, the thiohydroxy group of the polythiol reacts with the isocyanate group of the polyisocyanate to yield a reaction product having the following intramolecular bonds.

[0054] [Chemical Formula 1]

[0055]

[0056] In the above formula, Z represents an oxygen atom or a sulfur atom. * indicates a bonding position with an adjacent structure. The thiohydroxyl group reacts with the isocyanate group to form the above-mentioned bond where X is an oxygen atom, and reacts with the isothiocyanate group to form the above-mentioned bond where X is a sulfur atom. In this invention and this specification, the reaction product (resin) containing multiple of the above-mentioned bonds in one molecule is referred to as "polysulfuric acid ester".

[0057] Polyisocyanates can be plant-derived or non-plant-derived (e.g., petroleum-derived) polyisocyanates. Various polyisocyanates, such as aliphatic, alicyclic, and aromatic polyisocyanates, can be used. Each molecule of a polyisocyanate contains two or more isocyanate groups, preferably two to four, more preferably two or three. Specific examples of polyisocyanates include various compounds exemplified as polyisocyanate compounds in paragraph 0052 of Japanese Patent No. 5319037. Preferred polyisocyanates include hexamethylene diisocyanate, 1,5-pentane diisocyanate, isophorone diisocyanate, bis(isocyanate methyl)cyclohexane, dicyclohexylmethane diisocyanate, 2,5-bis(isocyanate methyl)-bicyclo[2.2.1]heptane, 2,6-bis(isocyanate methyl)-bicyclo[2.2.1]heptane, bis(4-isocyanate cyclohexyl)methane, 1,3- Aliphatic polyisocyanates such as bis(isocyanate-methyl)cyclohexane and 1,4-bis(isocyanate-methyl)cyclohexane; aromatic polyisocyanates such as bis(isocyanate-methyl)benzene, isophthalimide diisocyanate, terephthalimide diisocyanate, 1,3-diisocyanate-phenylene, toluene diisocyanate, 2,4-diisocyanate-toluene, 2,6-diisocyanate-toluene, and 4,4'-methylenebis(phenyl)isocyanate. In addition, halogen-substituted derivatives such as chlorinated and bromine-substituted derivatives, alkyl-substituted derivatives, alkoxy-substituted derivatives, nitro-substituted derivatives, prepolymer-type modifiers with polyols, carbodiimide-modified derivatives, urea-modified derivatives, biuret-modified derivatives, dimerization or trimerization reaction products of the above-mentioned polyisocyanates can be used. These compounds can be used alone or in combination of two or more.

[0058] In this invention and specification, "polymeric composition for optical materials" refers to a polymeric composition used in the manufacture of optical materials, and "polymeric composition" refers to a composition containing one or more polymeric compounds. The aforementioned polymeric composition for optical materials contains one or more polythiols obtained by thiolation of the hydroxyl groups of a plant-derived polyol, and one or more polyisocyanates, and may also contain or not contain one or more other polymeric compounds. In this invention and specification, "polymeric compound" refers to a compound capable of undergoing a polymerization reaction; polythiols and polyisocyanates are polymeric compounds. Specific examples of other polymeric compounds include polyols. Furthermore, specific examples of other polymeric compounds include polythiols other than those obtained by thiolation of the hydroxyl groups of a plant-derived polyol.

[0059] When the polymeric composition for optical materials described above contains a polyol as another polymeric compound, examples of such polyols include plant-derived polyols or non-plant-derived (e.g., petroleum-derived) polyols, with plant-derived polyols being preferred. Specific examples of plant-derived polyols include glycerol, sorbitol, isosorbide, sucrose, α-methyl glycoside, mannitol, 1,4-butanediol, 1,3-butanediol, and 1,3-propanediol.

[0060] When the polymerizable composition for the aforementioned optical materials includes polythiols other than those obtained by thiolation of the hydroxyl groups of plant-derived polyols as polymerizable compounds, non-plant-derived (e.g., petroleum-derived) polythiols can be cited as examples. Specific examples of non-plant-derived (e.g., petroleum-derived) polythiols include: mixtures of 4,7-bis(mercaptomethyl)-3,6,9-trithiaundecane-1,11-dithiol, 4,8-bis(mercaptomethyl)-3,6,9-trithiaundecane-1,11-dithiol, and 5,7-bis(mercaptomethyl)-3,6,9-trithiaundecane-1,11-dithiol, 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, pentaerythritol tetra(3-mercaptopropionate), pentaerythritol tetra(2-mercaptoacetate), etc. However, it should be noted that non-plant-derived polyols are not limited to the specific examples mentioned above. Non-plant-derived (e.g., petroleum-derived) polythiols can be synthesized by known methods. For example, reference can be made to Japanese Patent Nos. 3444682, 6632493, 6588639, 4928543, 6851763, 63-46213, 2005-336104, and 59-152367.

[0061] The polymeric composition for optical materials described above can be prepared by mixing the various components described above. The mixing ratio of the polythiol obtained by thiolation of the hydroxyl groups of a plant-derived polyol to the polyisocyanate in the polymeric composition for optical materials is not particularly limited. For example, as a molar ratio, it can be set to a range of 0.5 to 3.0 for the ratio of thiohydroxyl groups in the polythiol obtained by thiolation of the hydroxyl groups of the plant-derived polyol to the isocyanate groups in the polyisocyanate, preferably 0.6 to 2.0, and more preferably 0.8 to 1.3. Furthermore, in one embodiment, relative to 100% by mass of the total amount of the polymeric composition for optical materials, the polymeric composition for optical materials may contain, for example, 10% by mass or more (e.g., 10 to 50% by mass) of the polythiol obtained by thiolation of the hydroxyl groups of a plant-derived polyol.

[0062] When the polymeric composition for optical materials contains a polyol, the content of the polyol relative to 100% by mass of the total amount of the polymeric composition for optical materials can be, for example, 10% by mass or less (for example, 1 to 10% by mass).

[0063] When the polymeric composition for optical materials contains polythiols other than those obtained by thiolation of the hydroxyl groups of plant-derived polyols, the content of such polythiols relative to 100% by mass of the polymeric composition for optical materials may be, for example, 20% by mass or less (e.g., 1 to 20% by mass).

[0064] When preparing the polymeric composition for optical materials described above, one or more other components besides those described above may also be mixed. Specific examples of such other components include, for instance, reaction catalysts for the reaction of polythiocyanates with polythiocyanates. For other compatible components, see, for example, paragraphs 0055, 0057, and 0058-0064 of Japanese Patent No. 5319037. Furthermore, one or more commercially available additives, typically used as additives to various resins such as polythiourethane resins, may be used. The preparation of the polymeric composition for optical materials can be carried out by simultaneously or sequentially mixing the various components described above in any order. The preparation method is not particularly limited, and any method known as a method for preparing polymeric compositions may be used without restriction.

[0065] Optical materials and their manufacturing methods

[0066] One aspect of the present invention relates to an optical material, which is a cured product formed by curing the aforementioned optical material with a polymeric composition.

[0067] In addition, one aspect of the present invention relates to a method for manufacturing an optical material, comprising: manufacturing a polymeric composition for optical materials by the above-described manufacturing method, and curing the manufactured polymeric composition for optical materials to obtain a cured product.

[0068] The aforementioned optical materials can be lenses such as spectacle lenses. The curing reaction of the aforementioned optical materials with the polymeric composition can be carried out by various curing processes capable of curing the polymeric composition. For example, to manufacture a cured product having a lens shape (also called a "plastic lens"), casting polymerization is preferred. In casting polymerization, a curable composition can be injected into the cavity of a molding die having two molds opposite each other at a given interval and a cavity formed by closing the aforementioned interval, and polymerization (curing reaction) of the curable composition can be carried out within the cavity to obtain a cured product. For details regarding the molding dies that can be used in casting polymerization, please refer, for example, to paragraphs 0012-0014 of Japanese Patent Application Publication No. 2009-262480 and Figure 1 of that publication. It should be noted that the aforementioned publication shows a molding die in which the interval between the two molds is closed by a gasket as a sealing member, but a strip can also be used as a sealing member.

[0069] In one method, casting polymerization can be carried out as follows: A polymerizable composition is injected into the mold cavity through an injection port provided on the side of the mold. After injection, the polymerizable composition is preferably polymerized (curing reaction) by heating, thereby curing the polymerizable composition and obtaining a cured product with the internal shape of the cavity transferred onto it. The polymerization conditions are not particularly limited and can be appropriately set according to the composition of the polymerizable composition, etc. As an example, the mold with the polymerizable composition injected into the cavity can be heated at a temperature of 10~150°C for about 1~72 hours, but is not limited to these conditions. In this invention and this specification, the heating temperature and other temperatures related to casting polymerization refer to the atmosphere temperature (e.g., furnace temperature) where the mold is placed. Furthermore, during heating, the temperature can be increased at any rate, and the temperature can be decreased (cooled) at any rate. After the polymerization (curing reaction) is completed, the cured product inside the cavity is demolded from the mold. As is typically done in casting polymerization, the cured material can be demolded from the molding die by removing the upper and lower molds that form the cavity and the liner or strip in any order. The cured material after demolding is preferably used as an eyeglass lens (more specifically, a lens substrate). The cured lens substrate used as an eyeglass lens can typically be subjected to subsequent processes after demolding, such as annealing, grinding (e.g., rounding), polishing, coating formation (e.g., applying a base coating to improve impact resistance, or a hard coating to improve surface hardness). Furthermore, various functional layers, such as an anti-reflective layer or a water-repellent layer, can be formed on the lens substrate. Known techniques can be applied to these processes without any limitations. In this way, an eyeglass lens with the aforementioned cured material as the lens substrate can be obtained. Furthermore, eyeglasses can be obtained by mounting this eyeglass lens onto a frame.

[0070] The biomass ratio of the aforementioned optical material can be, for example, 20% or more. Alternatively, the biomass ratio of the aforementioned optical material can be 100%, or it can be less than 100%, 90%, 80%, 70%, 60%, or 50%. From the viewpoint of effectively utilizing non-fossil resources, optical materials with a high biomass ratio are desirable. The biomass ratio can be determined using known methods. Specific examples of methods for calculating the biomass ratio of optical materials include the methods described in the embodiments described later.

[0071] In one embodiment, the aforementioned optical material can exhibit a high refractive index. For example, the refractive index ne of the aforementioned optical material can be 1.50 or higher, or 1.55 or higher. Alternatively, the refractive index ne of the aforementioned optical material can be 1.76 or lower. The refractive index ne is the refractive index at a wavelength of 546.1 nm.

[0072] Example

[0073] The present invention will now be described in more detail with reference to embodiments. However, the present invention is not limited to the embodiments shown in the examples. Unless otherwise specified, the operations and evaluations described below were performed in air at room temperature (approximately 20-25°C).

[0074] [Example 1]

[0075] (1) Thiolation of hydroxyl groups in plant-derived polyols

[0076] 92.1 g (1.0 mol) of plant-derived glycerol was mixed with 100 ml of purified water, 570.9 g (7.5 mol) of thiourea, and 911.4 g (9.0 mol) of 36% hydrochloric acid. The mixture was stirred under reflux at 110 °C for 9 hours. After cooling to room temperature, 400 ml of toluene was added, followed by the slow addition of 1801.2 g (13.5 mol) of 30% sodium hydroxide aqueous solution. Hydrolysis was carried out at 60 °C for 4 hours. The resulting organic layer was washed twice, successively with 100 ml of 36% hydrochloric acid and 100 ml of water. Toluene was removed by rotary evaporation to obtain the crude product. Impurities were then removed by simple distillation to obtain 80.0 g (0.57 mol, 99% purity) of the target polythiol compound (trithioglycerol, hereinafter referred to as "TTG").

[0077] The determination was based on the ASTM D6866 METHOD B standard, and the biomass ratio was calculated using the following formula, with a result of 100%.

[0078] Biomass ratio = (Number of carbon atoms from plant sources / (Number of carbon atoms from plant sources + Number of carbon atoms from non-plant sources)) × 100

[0079] (2) Lens manufacturing

[0080] 64.8 parts by weight of petroleum-derived phthalimide diisocyanate (hereinafter referred to as "XDI"), 0.01 parts by weight of dimethyltin dichloride as a curing catalyst, 0.20 parts by weight of acidic phosphate ester "JP-506H" (manufactured by Jōhoku Chemical Industry Co., Ltd.) as a release agent, and 0.5 parts by weight of ultraviolet absorber "SEESORB 707" (manufactured by SHIPRO KASEI Co., Ltd.) were mixed and dissolved. Then, 35.2 parts by weight of TTG obtained in (1) above were added and mixed to obtain a homogeneous solution.

[0081] The homogeneous solution was degassed at 200 Pa for 1 hour and then filtered using a 5.0 μm PTFE (polytetrafluoroethylene) filter.

[0082] Next, a lens mold consisting of glass molds with diameters of 75mm, -4.00D, and 0.00D, and a strip is injected.

[0083] The mold was slowly heated from 15°C to 100°C in an electric furnace over 20 hours, and held at 100°C for 2 hours to carry out the polymerization reaction. After the polymerization reaction was completed, the mold was removed from the electric furnace, and the lens was obtained by demolding. The obtained lens was further annealed in an annealing furnace at a temperature of 100°C for 3 hours.

[0084] [Example 2]

[0085] The XDI of Example 1 was changed to a mixture of petroleum-derived 2,5-bis(isocyanate methyl)-bicyclo[2.2.1]heptane and petroleum-derived 2,6-bis(isocyanate methyl)-bicyclo[2.2.1]heptane (hereinafter referred to as "petroleum-derived NBDI"). Otherwise, the lens was made using the same method as described above.

[0086] [Example 3]

[0087] (1) Thiolation of hydroxyl groups in plant-derived polyols

[0088] 50 g (342 mmol) of isosorbide from plant sources and 500 mL of dry dichloromethane were added to a reaction vessel. The mixture was then cooled to 0 °C, and 48 mL (342 mmol) of triethylamine was added. 27.2 mL (419 mmol) of methanesulfonic acid was added dropwise over 15 minutes. The mixture was then heated to room temperature and stirred for 2 hours. After washing the organic layer to remove moisture, the solvent was removed under reduced pressure to obtain 80 g (265 mmol) of reaction intermediate A. Next, 80 g (265 mmol) of reaction intermediate A and 500 mL of dimethylacetamide (DMA) were added, and the mixture was stirred at room temperature for 30 minutes. Then, 60 g (530 mmol) of potassium thioacetate was added, and the mixture was stirred at 120 °C for 3 hours. After washing the organic layer to remove moisture, the solvent was removed under reduced pressure to obtain 80 g (168 mmol) of reaction intermediate B.

[0089] 44 g (168 mmol) of reaction intermediate B and 500 mL of anhydrous THF were added to a 1 L flask and stirred at room temperature for 30 minutes. The flask was then sealed with nitrogen and cooled to 0 °C. 7.4 g (168 mmol) of LiAlH4 was added and stirred for 1 hour. The reaction solution was diluted with THF (tetrahydrofuran), dehydrated with sodium sulfate, and the supernatant was concentrated under reduced pressure to obtain the crude product. Impurities were then removed by two simple distillations to obtain 12 g (67 mmol, 99% purity, liquid at room temperature) of 1,4:3,6-dihydro-2,5-dithio-D-mannitol (hereinafter referred to as "ISH"), the target compound. The biomass ratio was determined in the same manner as in Example 1, and the result was 100%.

[0090] (2) Lens manufacturing

[0091] 0.01 parts by mass of dimethyl tin dichloride, 0.20 parts by mass of "JP-506H" (manufactured by Jōhoku Chemical Industry Co., Ltd.), and 0.5 parts by mass of "SEESORB 707" (manufactured by SHIPRO KASEI Co., Ltd.) were mixed and dissolved in 60.5 parts by mass of petroleum-derived XDI. Then, 19.6 parts by mass of TTG obtained in Example 1 (1) and 0.0 parts by mass of ISH2 obtained in Example 3 (1) were added and mixed to obtain a homogeneous solution. Subsequently, a lens was made using the same method as in Example 1.

[0092] [Example 4]

[0093] The XDI was replaced with petroleum-derived NBDI, and the lens was otherwise manufactured using the same method as in Example 3.

[0094] [Example 5]

[0095] The TTG was replaced with a petroleum-derived polythiol 1 (a mixture of 4,7-bis(mercaptomethyl)-3,6,9-trithiaundecane-1,11-dithiol, 4,8-bis(mercaptomethyl)-3,6,9-trithiaundecane-1,11-dithiol and 5,7-bis(mercaptomethyl)-3,6,9-trithiaundecane-1,11-dithiol) synthesized by a known method. Otherwise, the lens was made using the same method as in Example 3.

[0096] [Example 6]

[0097] The TTG was replaced with petroleum-derived polythiol 1 synthesized by a known method, and the lens was otherwise made using the same method as in Example 4.

[0098] [Example 7]

[0099] 0.01 parts by weight of dimethyl tin dichloride, 0.20 parts by weight of "JP-506H" (manufactured by Jōhoku Chemical Industry Co., Ltd.), and 0.5 parts by weight of "SEESORB 707" (manufactured by SHIPRO KASEI Co., Ltd.) were mixed with 66.9 parts by weight of petroleum-derived XDI and dissolved. Then, 27.8 parts by weight of TTG obtained in (1) of Example 1 and 5.3 parts by weight of plant-derived 1,3-butanediol were added and mixed, and the mixture was stirred continuously until a clear, homogeneous solution was formed. After this, a lens was made using the same method as in Example 1.

[0100] [Example 8]

[0101] The XDI was replaced with petroleum-derived NBDI, and the lens was otherwise manufactured using the same method as in Example 7.

[0102] [Comparative Example 1]

[0103] 0.01 parts by weight of dimethyl tin dichloride, 0.20 parts by weight of "JP-506H" (manufactured by Jōhoku Chemical Industry Co., Ltd.), and 0.5 parts by weight of "SEESORB 707" (manufactured by SHIPRO KASEI Co., Ltd.) were mixed and dissolved in 75.8 parts by weight of petroleum-derived XDI. Then, when 24.2 parts by weight of vegetable-derived glycerin were added and mixed, the cloudy mixture exothermized and gelled, thus failing to produce lenses.

[0104] [Comparative Example 2]

[0105] The XDI was replaced with petroleum-derived NBDI. Otherwise, the same method as Comparative Example 1 was used to try to make the lens. However, as with Comparative Example 1, the lens could not be made because the mixed solution gelled.

[0106] [Comparative Example 3]

[0107] 0.01 parts by weight of dimethyl tin dichloride, 0.20 parts by weight of "JP-506H" (manufactured by Jōhoku Chemical Industry Co., Ltd.), and 0.5 parts by weight of "SEESORB 707" (manufactured by SHIPRO KASEI Co., Ltd.) were mixed and dissolved in 65.6 parts by weight of petroleum-derived XDI. Then, when 23.0 parts by weight of plant-derived isosorbide and 11.5 parts by weight of glycerin were added and mixed, the isosorbide, as a solid, did not dissolve in the mixed solution, and a portion of the mixed solution gelled, thus failing to produce lenses.

[0108] [Comparative Example 4]

[0109] The XDI was replaced with petroleum-derived NBDI. Otherwise, the same method as Comparative Example 1 was used to try to make the lens. However, as with Comparative Example 3, isosorbide did not dissolve in the mixed solution, and part of the mixed solution gelled, so the lens could not be made.

[0110] Table 1 shows the monomer ratios (molar ratios) of each polymerizable composition of Examples 1-8 and Comparative Examples 1-4. Petroleum-derived polyisocyanates were used as polyisocyanates, but plant-derived polyisocyanates can also be used.

[0111]

[0112] [Comparative Example 5]

[0113] The lens was manufactured using the same steps as in Example A1 of Japanese Patent No. 6571968 (Patent Document 1).

[0114] [Comparative Example 6]

[0115] The lens was manufactured using the same steps as in Example A6 of Japanese Patent No. 6571968 (Patent Document 1).

[0116] For each lens of Examples 1-8 and Comparative Examples 5 and 6, the biomass ratio was determined by the following formula based on the formulation of the polymeric composition used in the manufacture of the lens.

[0117] Biomass ratio = {[(b) mass parts × (b) biomass ratio / 100] + [(c) mass parts × (c) biomass ratio / 100]} / [(a) + (b) + (c) + (d) total mass (mass parts)]

[0118] The terms (a) to (d) in the above formula are as follows.

[0119] (a): Petroleum-derived polyisocyanates

[0120] (b): Polythiols obtained by thiolation of the hydroxyl groups of plant-derived alcohols.

[0121] (c): Plant-derived polyols

[0122] (d): Petroleum-derived polythiols

[0123] (c) The biomass ratio was determined based on ASTM D6866 METHOD B and calculated using the following formula. The biomass ratio for all plant-derived polyols was 100%.

[0124] Biomass ratio = (Number of carbon atoms from plant sources / (Number of carbon atoms from plant sources + Number of carbon atoms from non-plant sources)) × 100

[0125] [Evaluation Method]

[0126] <Refractive index ne>

[0127] The refractive index ne of each lens in Examples 1-8 and Comparative Examples 5 and 6 was measured using a KPR-2000 precision refractometer manufactured by Kalnew Optical Industries at a measurement temperature of 23°C.

[0128] <Wave>

[0129] For each lens of Examples 1-8 and Comparative Examples 5 and 6, a projection inspection was performed using an appearance inspection apparatus (Ushio Electric Injection Co., Ltd. Optical Modulex SX-UI251HQ). A high-pressure UV lamp (Ushio Electric Injection Co., Ltd. USH-102D) was used as the light source. A white screen was set up at a distance of 1 m from the light source. The lens to be evaluated was inserted between the light source and the screen, and the projected image on the screen was observed. Evaluation was performed according to the following criteria.

[0130] (Evaluation Criteria)

[0131] A: There are absolutely no linear irregularities in the projected image.

[0132] B: The projected image contains sparse, irregular lines.

[0133] C: The projected image contains dense, irregular lines.

[0134] D: The projected image contains obvious linear irregularities.

[0135] <Haze Value>

[0136] For each lens of Examples 1-8 and Comparative Examples 5 and 6, the haze value was measured using a haze meter (MH-150 manufactured by Murakami Color Technology Research Institute Co., Ltd.).

[0137] The results are shown in Table 2.

[0138]

[0139] The results shown in Table 2 confirm that, compared with the lenses of Comparative Examples 5 and 6, the lenses of Examples 1-8 exhibited reduced haze and suppressed the formation of wave veins. Furthermore, it can be confirmed that the lenses of Examples 1-8 are high-refractive-index lenses compared with the lenses of Comparative Examples 5 and 6.

[0140] The various schemes and methods described in this specification can be combined in any combination, resulting in two or more combinations.

[0141] It should be understood that all the embodiments disclosed herein are exemplary and do not constitute a limitation. The scope of this invention is not defined by the foregoing description, but by the claims, which include all modifications within the same meaning and scope as the claims.

[0142] Industrial applicability

[0143] One aspect of the present invention is useful in the technical field of various optical materials.

Claims

1. A polythiol obtained by thiolation of the hydroxyl groups of a plant-derived polyol.

2. The polythiol according to claim 1, wherein, The plant-derived polyols are glycerol, sorbitol, isosorbide, sucrose, α-methyl glycoside, mannitol, 1,4-butanediol, 1,3-butanediol, or 1,3-propanediol.

3. A polymeric composition for optical materials, comprising: One or more polythiols as described in claim 1 or 2, and One or more polyisocyanates.

4. The polymeric composition for optical materials according to claim 3, further comprising a plant-derived polyol.

5. An optical material, which is a cured product formed by curing the optical material of claim 3 with a polymeric composition.

6. The optical material according to claim 5, wherein it is a lens.

7. The optical material according to claim 6, wherein it is a spectacle lens.

8. An optical material, which is a cured product obtained by curing the optical material of claim 4 with a polymeric composition.

9. The optical material according to claim 8, wherein it is a lens.

10. The optical material according to claim 9, wherein it is a spectacle lens.

11. A method for producing polythiols, comprising: Thiolization of the hydroxyl groups of plant-derived polyols.

12. A method for manufacturing a polymeric composition for optical materials, comprising: The manufacturing method of claim 11 is used to manufacture polythiols, and The manufactured polythiols are mixed with one or more polyisocyanates.

13. A method for manufacturing an optical material, comprising: The manufacturing method of claim 12 is used to manufacture a polymeric composition for optical materials, and The manufactured optical material is cured by using a polymeric composition to obtain a cured product.

14. The method for manufacturing the optical material according to claim 13, wherein, The optical material is a lens.

15. The method for manufacturing the optical material according to claim 14, wherein, The lens is an eyeglass lens.

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