Method for producing a polythiol composition

Abstract

The present invention provides a method for producing a polythiol composition that does not require a neutralization process. [Solution] A method for producing a polythiol composition, comprising a reaction step of reacting a thiourethane resin with an alcohol under high temperature and high pressure conditions to produce a polythiol composition.

Description

[Technical Field]

[0001] This disclosure relates to a method for producing a polythiol composition. [Background technology]

[0002] Plastic lenses, which contain resin, are lighter, less prone to breakage, and can be dyed compared to inorganic lenses, and have therefore become rapidly popular in recent years for applications such as eyeglass lenses and camera lenses. For example, various studies have been conducted on lenses containing thiourethane resin.

[0003] For the production of thiourethane resin, raw materials (hereinafter also referred to as "thiourethane resin raw materials") include, for example, polythiol compositions such as 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane and polyisocyanate compounds such as m-xylylene diisocyanate (XDI). Polyisocyanate compounds are produced, for example, from polyamine compounds. Polyamine compounds, which are raw materials for polyisocyanate compounds, also fall under the category of thiourethane resin raw materials (i.e., raw materials for producing thiourethane resin).

[0004] Lenses containing thiourethane resin (e.g., eyeglass lenses) are manufactured by machining molded bodies containing thiourethane resin. As a result, the lens manufacturing process can generate large amounts of waste, such as machining dust containing thiourethane resin. Furthermore, the manufacturing process of molded bodies containing thiourethane resin can result in defective molded or machined products. Such waste has typically been incinerated or landfilled without being effectively utilized (i.e., recycled). Therefore, from the viewpoint of effective utilization of materials, a technology has been developed to produce polythiol compositions by reacting cutting powder containing thiourethane resin, molded or processed defective products, which are considered waste materials, with other materials (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2021 / 157701 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, as described in Patent Document 1, conventional methods for producing polythiol compositions using amine compounds required a neutralization process for the recovered material. Therefore, from the viewpoint of reducing energy consumption and suppressing by-product formation, there was a strong desire to develop a reaction system that could produce polythiol compositions using thiourethane resin as a starting material without requiring a neutralization process.

[0007] Under these circumstances, one aspect of the present disclosure aims to provide a method for producing a polythiol composition that does not require a neutralization process. [Means for solving the problem]

[0008] Embodiments of this disclosure relate to the following [1] to [8]. [1] A method for producing a polythiol composition, comprising a reaction step of reacting a thiourethane resin with an alcohol under high temperature and high pressure reaction conditions to produce a polythiol composition. [2] A method for producing the polythiol composition according to [1] above, wherein the reaction temperature under the reaction conditions is greater than 130°C and 270°C or less. [3] A method for producing the polythiol composition according to [1] or [2] above, wherein the reaction pressure under the reaction conditions is 2.0 MPa or more and less than 22.0 MPa. [4] A method for producing a polythiol composition according to any one of [1] to [3] above, wherein the reaction time under the reaction conditions is 0.3 to 20 hours. [5] The alcohol having 1 to 20 carbon atoms, a method for producing the polythiol composition according to any one of [1] to [4] above. [6] A method for producing a polythiol composition according to any one of [1] to [5] above, wherein the alcohol is at least one selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol, t-butanol, 1-octanol, 2-octanol, benzyl alcohol, and 2-hexyl-1-decanol. [7] A method for producing a polythiol composition according to any one of [1] to [6] above, wherein the reaction step is carried out under a carbon dioxide atmosphere. [8] A method for producing the polythiol composition according to any one of [1] to [7] above, wherein the polythiol composition comprises at least one selected from the group consisting of 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, and 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane. [Effects of the Invention]

[0009] According to one aspect of this disclosure, a method for producing a polythiol composition can be provided that allows the polythiol composition to be obtained without requiring a neutralization process. [Modes for carrying out the invention]

[0010] The following description is based on an example of an embodiment of the present disclosure. However, the embodiment shown below is illustrative for embodying the technical concept of the present disclosure, and the present disclosure is not limited to the following description. This disclosure also includes any selected or combined forms of the information described herein. In this specification, any provision deemed preferable can be selected at will, and any combination of preferred provisions is considered more preferable. In this specification, the notation "XX~YY" means "XX or greater and YY or less". In this specification, the lower and upper limits described in steps for a preferred numerical range (e.g., range of content, etc.) can be combined independently. For example, from the description "preferably 10 to 90, more preferably 30 to 60", the "preferred lower limit (10)" and the "more preferred upper limit (60)" can be combined to arrive at "10 to 60". In this specification, the amount of each component contained in a composition means the total amount of any multiple substances present in the composition, unless otherwise specified. In this specification, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, provided that their intended purpose is achieved. In this specification, the term "reaction system" means "the reaction system of the reaction step in the method for producing a polythiol composition." In this specification, "room temperature" refers to the ambient temperature without temperature control such as heating or cooling, and is generally 20°C. In this specification, the term "high temperature" means "temperature above 130°C." In this specification, the term "high pressure" means "a pressure of 2 MPa or higher." In addition to the essential components consisting of thiourethane resin and alcohol, the reaction system in the reaction process may also contain optional components such as carbon dioxide and nitrogen. Therefore, the content (mass%) in the reaction system refers to the content (mass%) when the total content of the essential and optional components in the reaction system is set to 100 mass%. In this specification, when a reaction system (composition) "contains a certain component (hereinafter referred to as "component X") as a main component, it means that the content of component X (or, if component X consists of two or more compounds, the total content of the two or more compounds) is 50% by mass or more of the total amount of the reaction system (composition). The content of the main component, component X, is preferably 60% by mass or more, more preferably 70% by mass or more, and particularly preferably 80% by mass or more, based on the total amount of the reaction system (composition).

[0011] [Method for Producing Polythiol Composition] The method for producing a polythiol composition according to an embodiment of the present disclosure includes a reaction step of reacting a thiourethane resin and an alcohol under reaction conditions of high temperature and high pressure to produce a polythiol composition. Since the method for producing a polythiol composition according to an embodiment of the present disclosure reacts a thiourethane resin and an alcohol under reaction conditions of high temperature and high pressure, a polythiol composition can be obtained without requiring a neutralization process (for example, refer to the following reaction formula (1) and the following reaction formula (1-1)).

[0012] [Chemical formula] ···(1) [Chemical formula] ···(1-1)

[0013] R in reaction formula (1) 1 is formula (a-1), formula (a-2), formula (a-3), formula (a-4), formula (a-5), formula (a-6), formula (a-7) or formula (a-8): [Chemical formula] (In the formula, * is the bonding site with the nitrogen atom of the thiourethane bond in reaction formula (1), and R 4 is a substituent described later. n is an integer of 0 to 4. When n is any of 2 to 4, R 4 may be the same or different from each other.) It preferably contains a structure represented by

[0014] R in reaction formula (1) 2 is formula (b-1), formula (b-2), formula (b-3), formula (b-4), formula (b-5) or formula (b-6): [Chemical formula] (In the formula, * represents the bonding site with the sulfur atom of the thiourethane bond in Reaction Formula (1).) It preferably contains a structure represented by this.

[0015] Reaction Formula (1-1) is R 1 is Formula (a-1), and R 2 is Formula (b-1), and it represents an example of Reaction Formula (1).

[0016] Regarding the number of carbon atoms of R 3 in Reaction Formula (1) and Reaction Formula (1-1), there is no particular limitation, but it is preferably 1 to 20, more preferably 1 to 10, and particularly preferably 1 to 4. Regarding R 3 OH in Reaction Formula (1) and Reaction Formula (1-1), there is no particular limitation, and examples include methanol, ethanol, n-propanol, isopropanol, n-butanol, t-butanol, 1-octanol, 2-octanol, benzyl alcohol, 2-hexyl-1-decanol, etc. These may be used alone or in combination of two or more. Among these, methanol, ethanol, n-propanol, n-butanol, and t-butanol are preferable.

[0017] R 4There are no particular restrictions on the substituents represented by , for example, each independently: hydroxyl group; linear or branched alkyl groups having 1 to 18 carbon atoms such as methyl, ethyl, propyl, butyl, pentyl, and hexyl groups; monocyclic or bicyclic cyclic aliphatic alkyl groups having 5 to 18 carbon atoms such as cyclopentyl and cyclohexyl groups; linear or branched alkoxy groups having 1 to 24 constituent atoms such as methoxy, ethoxy, and butoxy groups; non-aromatic cyclic substituents having 1 to 24 constituent atoms; Straight-chain or branched perfluoroalkyl groups having 1 to 18 carbon atoms, such as the difluoromethyl group; straight-chain or branched perfluoroalkoxy groups having 1 to 24 carbon atoms, such as the trifluoromethoxy group; straight-chain or branched alkyl sulfide groups having 1 to 24 constituent atoms, such as the methyl sulfide group, ethyl sulfide group, and butyl sulfide group; aryl groups such as the phenyl group, naphthyl group, anthracenyl group, fluoranthenyl group, phenanthryl group, pyranyl group, perilenyl group, styryl group, and fluorenyl group; phenyloxy group, etc. Aryloxy groups; aryl sulfide groups such as phenyl sulfide group; heteroaryl groups such as pyridyl group, furanyl group, thienyl group, pyrrolyl group, benzofuranyl group, benzothiophenyl group, indolyl group, dibenzofuranyl group, dibenzothiophenyl group, carbazolyl group, diazolyl group, triazolyl group, quinolinyl group, phenothiazinyl group, phenoxazinyl group, phenazinyl group, thianthyl group, acridinyl group, etc.; amino group (-NH2); monoalkyl group such as monomethylamino group. Examples include amino groups; dialkylamino groups such as dimethylamino groups; monoarylamino groups such as monophenylamino groups; diarylamino groups such as diphenylamino groups; cyclic amino groups such as piperidino groups, morpholino groups, thiomorpholino groups, tetrahydroquinolino groups, and tetrahydroisoquinolino groups; ethynyl groups; mercapto groups; silyl groups; sulfonic acid groups; alkylsulfonyl groups; formyl groups; carboxyl groups; cyano groups; halogen atoms such as fluorine, chlorine, bromine, and iodine atoms; and so on.

[0018] A method for producing a polythiol composition according to the embodiments of this disclosure includes at least a reaction step, and optionally includes other steps such as a separation step, a classification step, a sieving step, a washing step, and a crushing (grinding) step. The following describes each step that may be included in the method for producing a polythiol composition.

[0019] [[Reaction Process]] The reaction process involves reacting a thiourethane resin with an alcohol under high temperature and high pressure conditions to produce a polythiol composition. It is preferable to introduce carbon dioxide into the reaction system to improve the yield of the polythiol composition. The reason why alcohol is essential in the reaction process is that, as can be seen from Comparative Example 1 described later, neutralization is necessary if an amine is used instead of alcohol, and as can be seen from Comparative Example 2 described later, the yield is poor if water is used instead of alcohol. Without alcohol, a polythiol composition cannot be obtained in good yield without a neutralization process. The reason for carrying out the reaction under high-temperature conditions in the reaction process is that, as can be seen from the fact that a polythiol composition cannot be obtained in Comparative Example 3 (130°C), which will be described later, a temperature higher than 130°C is required to obtain the polythiol composition. The reason for carrying out the reaction under high pressure conditions during the reaction process is that the decomposition reaction will not occur unless the initial pressurized pressure is 2.0 MPa or higher.

[0020] <Thiourethane resin> Thiourethane resin is the starting material in this process and in the method for producing the polythiol composition. There are no particular restrictions on the thiourethane resin, and examples include thiourethane resins described in publicly available documents such as Japanese Patent Publication No. 63-46213, Japanese Patent Publication No. 2-270859, Japanese Patent Publication No. 7-252207, and International Publication No. 2008 / 047626.

[0021] Thiourethane resins are typically produced as reaction products using polyisocyanate compounds and polythiol compositions as raw materials.

[0022] Preferably, the thiourethane resin is recovered during at least one of the following processes: the manufacturing process of eyeglass lenses, the manufacturing process of eyeglasses, and the disposal process of eyeglasses. According to this embodiment, recycling of the thiourethane resin, which is a material for eyeglass lenses, is achieved. Here, the manufacturing process of eyeglass lenses refers to the process of producing resin by mixing monomers, which are the raw materials for resin, and casting polymerization, and / or the process of obtaining eyeglass lenses by cutting and shaping the resin molded body; the manufacturing process of eyeglasses refers to the process of producing eyeglasses by combining eyeglass lenses with other components such as eyeglass frames; and the disposal process of eyeglasses refers to the process of disposing of eyeglasses that have been manufactured but are no longer needed, used eyeglasses, etc. In either process, thiourethane resin, the material used for eyeglass lenses, may be generated as waste. It is preferable to use the thiourethane resin produced in at least one of these processes as a starting material, and to react this thiourethane resin with an alcohol and, if necessary, an optional component such as carbon dioxide or nitrogen, under high temperature and high pressure reaction conditions to obtain a polythiol composition, which is a decomposition product of the thiourethane resin.

[0023] As described above, the method for producing the polythiol composition of this disclosure makes it possible to reduce the amount of thiourethane resin that is incinerated by using used thiourethane resin for the production of the polythiol composition, and as a result it is possible to reduce the generation of greenhouse gases such as carbon dioxide, sulfur oxides, nitrogen oxides, and other air pollutants. The method for producing the polythiol composition described herein makes it possible to reduce the generation of carbon dioxide, nitric oxide, and sulfur dioxide.

[0024] The above starting materials preferably include cutting powder containing thiourethane resin. In the reaction step for producing the polythiol composition in this embodiment, the thiourethane resin, the alcohol, and the optional component are brought into contact with the cutting powder containing the thiourethane resin, the alcohol, and the optional component under high temperature and high pressure conditions, thereby causing the thiourethane resin, the alcohol, and the optional component to react under high temperature and high pressure conditions. In this embodiment, the reactivity between the thiourethane resin in the starting material, the alcohol, and the above-mentioned optional component is superior, making it possible to produce the polythiol composition more effectively.

[0025] (Powder containing thiourethane resin) In the reaction process, it is preferable to contact a powder containing thiourethane resin (hereinafter also referred to as "thiourethane resin powder") with alcohol and an optional component such as carbon dioxide or nitrogen under high temperature and high pressure conditions, thereby reacting the thiourethane resin in the powder with the alcohol and the optional component under high temperature and high pressure conditions. This makes it possible to further improve the reaction efficiency between the thiourethane resin, the alcohol and the optional component. There are no particular restrictions on the method of bringing the thiourethane resin, the alcohol, and the optional component into contact. For example, one method is to introduce the thiourethane resin powder, the alcohol, and the optional component into a reaction vessel and stir them. In this example, there are no particular restrictions on the order in which the thiourethane resin powder, the alcohol, and the optional component are introduced into the reaction vessel.

[0026] The thiourethane resin powder is not particularly limited, but is preferably cutting powder (including the concept of abrasive powder; the same applies hereinafter) from a molded article containing thiourethane resin and / or the cutting powder that has been sieved (i.e., cutting powder that has passed through the sieve). Cutting powder from molded bodies containing thiourethane resin is generated, for example, when manufacturing optical materials (e.g., lenses) by cutting molded bodies containing thiourethane resin. Furthermore, the thiourethane resin powder may also be a lump powder obtained by crushing and / or grinding a molded body containing thiourethane resin.

[0027] There are no particular restrictions on the content of thiourethane resin in the reaction system of the reaction step, but from the viewpoint of further improving the reactivity of the thiourethane resin, it is preferably 1.0 to 50.0% by mass, more preferably 1.5 to 40.0% by mass, and particularly preferably 2.0 to 30.0% by mass.

[0028] (Polyisocyanate composition as a raw material for thiourethane resin) The polyisocyanate composition used as a raw material for the thiourethane resin may consist of only one type or two or more types. The polyisocyanate composition used as a raw material for thiourethane resin preferably contains a polyisocyanate compound that has two or more isocyanate groups. There are no particular limitations on specific examples of polyisocyanate compounds, and examples include pentamethylene diisocyanate, hexamethylene diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, isophorone diisocyanate, bis(isocyanatomethyl)cyclohexane, bis(isocyanatocyclohexyl)methane, 2,5-bis(isocyanatomethyl)bicyclo-[2.2.1]-heptane, 2,6-bis(isocyanatomethyl)bicyclo-[2.2.1]-heptane, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, phenylene diisocyanate, etc. These may be used individually or in combination of two or more.

[0029] (Polythiol composition as a raw material for thiourethane resin) The polythiol composition used as a raw material for thiourethane resin may consist of only one polythiol compound or two or more polythiol compounds. The polythiol composition used as a raw material for thiourethane resin only needs to contain a polythiol compound containing two or more thiol groups (i.e., mercapto groups), and is not particularly limited in any other respect. There are no particular restrictions on specific examples of polythiol compounds, such as 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, pentaerythritol tetrakis(2-mercaptoacetate), pentaerythritol tetrakis(3-mercaptopropionate), 2,5-dimercaptomethyl-1,4-dithiane, bis(2-mercaptoethyl) sulfide, and diethylene glycol. Examples include bis(3-mercaptopropionate), methanedithiol, 1,2-ethanedithiol, 1,2,3-propanetrithiol, tetrakis(mercaptomethylthiomethyl)methane, tetrakis(2-mercaptoethylthiomethyl)methane, tetrakis(3-mercaptopropylthiomethyl)methane, bis(2,3-dimercaptopropyl)sulfide, 2,5-dimercapto-1,4-dithiane, 2,5-dimercaptomethyl-2,5-dimethyl-1,4-dithiane, 1,1,3,3-tetrakis(mercaptomethylthio)propane, 1,1,2,2-tetrakis(mercaptomethylthio)ethane, and 4,6-bis(mercaptomethylthio)-1,3-dithiane. These may be used individually or in combination of two or more.

[0030] (Other components that may be contained in thiourethane resin) The thiourethane resin may contain other components besides a polymer of at least one polyisocyanate compound and a polythiol composition. Other components that may be contained in the thiourethane resin are not particularly limited and include, for example, polymerization catalysts, internal release agents, resin modifiers, chain extenders, crosslinking agents, radical scavengers, light stabilizers, UV absorbers, antioxidants, oil-soluble dyes, fillers, adhesion improvers, antibacterial agents, antistatic agents, dyes, fluorescent whitening agents, fluorescent pigments, inorganic pigments, and the like.

[0031] ((polymerization catalyst)) There are no particular restrictions on the polymerization catalyst, and examples include tertiary amines, inorganic or organic acid salts of tertiary amines, metal compounds such as dimethyltin dichloride, quaternary ammonium salts, and organic sulfonic acids. These may be used individually or in combination of two or more.

[0032] ((Internal release agent)) There are no particular restrictions on the internal release agent; for example, acidic phosphate esters such as phosphate monoesters and phosphate diesters can be used. These may be used individually or in combination of two or more types.

[0033] ((Resin modifier)) There are no particular restrictions on the resin modifiers, and examples include episulfides, epoxy, organic acids, anhydrides of organic acids, (meth)acrylates, olefins, etc. These may be used individually or in combination of two or more types. Note that (meth)acrylate means at least one of acrylate and methacrylate.

[0034] <Alcohol> There are no particular restrictions on the number of carbon atoms in the alcohol in the reaction system of the reaction step, but it is preferably 1 to 20, more preferably 1 to 10, and most preferably 1 to 4. There are no particular restrictions on the alcohol used in the reaction system of the reaction step. Examples include methanol, ethanol, n-propanol, isopropanol, n-butanol, t-butanol, 1-octanol, 2-octanol, benzyl alcohol, and 2-hexyl-1-decanol. These may be used individually or in combination of two or more. Among these, methanol, ethanol, n-propanol, n-butanol, and t-butanol are preferred.

[0035] There are no particular restrictions on the alcohol content in the reaction system of the reaction step, but from the viewpoint of further improving the reactivity with the thiourethane resin, it is preferably 50.0 to 99.0% by mass, more preferably 60.0 to 98.5% by mass, and particularly preferably 70.0 to 98.0% by mass.

[0036] (Amount of alcohol used in the preparation) In the reaction process, the mass ratio of alcohol to thiourethane resin (i.e., mass ratio [alcohol / thiourethane resin]) can be adjusted as appropriate, but is preferably 1 to 70, more preferably 2 to 60, and particularly preferably 3 to 50. When the mass ratio of the preparation [alcohol / thiourethane resin] is 1 or greater, the formation of the polythiol composition is further promoted. When the mass ratio of the initial mixture [alcohol / thiourethane resin] is 70 or less, the residual alcohol in the reaction mixture can be further suppressed.

[0037] In the reaction process, the number of millimoles of alcohol added per 1 g of thiourethane resin is preferably 10 to 1000 mmol / g, more preferably 30 to 700 mmol / g, and particularly preferably 50 to 400 mmol / g.

[0038] In the reaction step, the amount of alcohol added to the thiourethane resin (additional amount [alcohol / thiourethane resin]) is preferably 1 to 100, more preferably 2 to 70, and particularly preferably 4 to 40.

[0039] <Carbon dioxide> In the reaction process, carbon dioxide is preferably introduced into the reaction system until the reaction vessel reaches a predetermined initial pressure (2 MPa in this embodiment). There are no particular restrictions on the initial pressure, but it is preferably 0.5 to 5 MPa, more preferably 1 to 4 MPa, and most preferably 1.5 to 3 MPa.

[0040] <Reaction solvent> In the reaction step, the thiourethane resin may be reacted with an alcohol and an optional component such as carbon dioxide or nitrogen in the presence of a reaction solvent. The reaction solvent refers to a reaction solvent other than the alcohol as an optional component, and examples include hydrocarbons having 5 to 12 carbon atoms (preferably 6 to 10, more preferably 7 to 9). These may be used individually or in combination of two or more types.

[0041] The hydrocarbons mentioned above are preferably hexane, heptane, octane, nonane, decane, xylene, mesitylene, or toluene, more preferably heptane, octane, nonane, xylene, mesitylene, or toluene, and particularly preferably xylene or toluene.

[0042] <Reaction temperature> The reaction temperature between the thiourethane resin, alcohol, and optional component in the reaction step is not particularly limited as long as it is high (above 130°C), but is preferably above 130°C and below 270°C, more preferably 135°C to 230°C, even more preferably 140°C to 230°C, and most preferably 150°C to 190°C. If the reaction temperature exceeds 130°C, the decomposition reaction of the thiourethane resin can proceed. The upper limit of the preferred reaction temperature range, 270°C, is the boiling point of methanol at 6.2 MPa. When the reaction temperature is within a preferred range, the yield of the polythiol compound as the main component in the target polythiol composition (i.e., the content of the main component relative to the total amount of the polythiol composition) can be further improved.

[0043] <Reaction pressure> The reaction pressure between the thiourethane resin, alcohol, and optional component in the reaction step is preferably 2.0 MPa or more and less than 22.0 MPa, more preferably 2.0 MPa or more and less than 10.0 MPa, and particularly preferably 2.0 to 7.0 MPa. The lower limit of the preferred reaction pressure range (2.0 MPa) is the initial pressurized pressure. The decomposition reaction will not occur unless the pressure is 2.0 MPa or higher. Keeping the reaction pressure below 22.0 MPa prevents the reaction from reaching a supercritical state, which would make handling the reaction process difficult. When the reaction pressure is less than 10.0 MPa, the conversion rate from thiourethane resin to polythiol compound can be improved.

[0044] <Reaction time> The reaction time between the thiourethane resin, alcohol, and optional components in the reaction step can be adjusted as appropriate, but is preferably 0.3 to 20 hours, more preferably 0.5 to 18 hours, and particularly preferably 1 to 8 hours. If the reaction time is above the lower limit, the yield at the optimal temperature (190°C) can be improved. On the other hand, if the reaction time is below the upper limit, it is possible to prevent the yield of the polythiol compound from decreasing due to an excessively long reaction time.

[0045] <Polythiol composition> In this disclosure, "polythiol composition" means a composition containing at least one polythiol compound, and may also contain other components such as urethane compounds, polyamine compounds, and polyisocyanate compounds. In this disclosure, the polythiol compound contained in the polythiol composition is also referred to as the "polythiol component." The polythiol composition preferably contains at least one polythiol compound as a main component. Here, "the polythiol composition contains at least one polythiol compound as a main component" means that the total content of at least one polythiol compound relative to the total amount of the polythiol composition is 50% by mass or more. There are no particular restrictions on the total content of at least one polythiol compound relative to the total amount of the polythiol composition, but it is preferably 60% by mass or more, more preferably 70% by mass or more, and particularly preferably 80% by mass or more.

[0046] Examples of polythiol compositions as target products include polythiol compositions containing known polythiol compounds. The polythiol composition as the target product and the polythiol composition as a raw material for the thiourethane resin as a starting material do not need to be completely identical. However, from the viewpoint of the performance of the thiourethane resin produced by the polythiol composition as the target product, it is preferable that the type of polythiol component as the main component in the polythiol composition as the target product and the type of polythiol component as the main component in the polythiol composition as a raw material are the same.

[0047] The target polythiol composition may have a reduced content of components other than the main component in the polythiol composition.

[0048] There are no particular restrictions on the use of the polythiol composition as the target product. The polythiol composition as the target product can be used, for example, in the production of thiourethane resins. Specific applications of the target polythiol composition include polythiol compositions for the manufacture of optical materials (e.g., eyeglass lenses). In other words, a specific example of the method for producing the polythiol composition of this disclosure is a method for producing a polythiol composition for the manufacture of optical materials. In this specific example, if cutting powder containing thiourethane resin generated during the manufacture of optical materials is used as the starting material, the effective utilization (i.e., recycling) of the material (thiourethane resin and its raw material, the polythiol composition) can be effectively realized. Furthermore, in the reaction process described herein, a polythiol composition can be obtained without a neutralization process by reacting a thiourethane resin, an alcohol, and an optional component under high temperature and high pressure reaction conditions. Therefore, even when the target polythiol composition is used in the manufacture of optical materials (e.g., lenses), optical materials with good performance can be obtained. The properties of optical materials include optical properties (e.g., refractive index and / or Abbe number), heat resistance, and specific gravity.

[0049] (Polythiol compounds) There are no particular restrictions on polythiol compounds, as long as they contain two or more thiol groups (also known as mercapto groups).

[0050] There are no particular restrictions on the polythiol compound, but suitable examples include 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, pentaerythritol tetrakis(2-mercaptoacetate), pentaerythritol tetrakis(3-mercaptopropionate), 2,5-dimercaptomethyl-1,4-dithiane, bis(2-mercaptoethyl) sulfide, and diethylene glycol bis(3-mercaptopropionate). These may be used individually or in combination of two or more. The polythiol composition may also contain at least one other component (for example, other polythiol compounds, components other than polythiol compounds, etc.) in addition to the polythiol compound contained as the main component.

[0051] Other polythiol compounds are not particularly limited and include, for example, methanedithiol, 1,2-ethanedithiol, 1,2,3-propanetrithiol, tetrakis(mercaptomethylthiomethyl)methane, tetrakis(2-mercaptoethylthiomethyl)methane, tetrakis(3-mercaptopropylthiomethyl)methane, bis(2,3-dimercaptopropyl)sulfide, 2,5-dimercapto-1,4-dithiane, 2,5-dimercaptomethyl-2,5-dimethyl-1,4-dithiane, 1,1,3,3-tetrakis(mercaptomethylthio)propane, 1,1,2,2-tetrakis(mercaptomethylthio)ethane, 4,6-bis(mercaptomethylthio)-1,3-dithiane, and the like. These may be included individually or in combination of two or more.

[0052] (Urethane compound) A urethane compound is any compound that contains one or more urethane bonds. There are no particular restrictions on the urethane compound, and examples include xylylene dicarbamate, 1,3-bis(methoxycarbonylaminomethyl)benzene, 1,3-bis(ethoxycarbonylaminomethyl)benzene, 1,3-bis(propoxycarbonylaminomethyl)benzene, and 1,3-bis(butoxycarbonylaminomethyl)benzene. These may be included individually or in combination of two or more. Among these, xylylene dicarbamate is preferred.

[0053] (Polyamine compounds) A polyamine compound can be any compound containing two or more amino groups. There are no particular restrictions on the polyamine compounds used, and examples include pentamethylenediamine, hexamethylenediamine, m-xylylenediamine, p-xylylenediamine, isophoronediamine, bis(aminomethyl)cyclohexane, bis(aminocyclohexyl)methane, 2,5-bis(aminomethyl)bicyclo-[2.2.1]-heptane, 2,6-bis(aminomethyl)bicyclo-[2.2.1]-heptane, tolylenediamine, 4,4'-diphenylmethanediamine, phenylenediamine, norbornanediamine, and the like. These may be used individually or in combination of two or more. Among these, m-xylylenediamine, 2,5-bis(aminomethyl)bicyclo-[2.2.1]-heptane, 2,6-bis(aminomethyl)bicyclo-[2.2.1]-heptane, and norbornanediamine are preferred, with m-xylylenediamine and norbornanediamine being more preferred.

[0054] (Polyisocyanate compounds) A polyisocyanate compound is any compound that contains two or more isocyanate groups. There are no particular restrictions on the polyisocyanate compound, and examples include pentamethylene diisocyanate, hexamethylene diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, isophorone diisocyanate, bis(isocyanatomethyl)cyclohexane, bis(isocyanatocyclohexyl)methane, 2,5-bis(isocyanatomethyl)bicyclo-[2.2.1]-heptane, 2,6-bis(isocyanatomethyl)bicyclo-[2.2.1]-heptane, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, phenylene diisocyanate, and the like. These may be used individually or in combination of two or more. Among these, m-xylylene diisocyanate, 2,5-bis(isocyanatomethyl)bicyclo-[2.2.1]-heptane, and 2,6-bis(isocyanatomethyl)bicyclo-[2.2.1]-heptane are preferred.

[0055] (Preferred embodiment of the process for producing a polythiol composition) The process for producing the polythiol composition preferably involves reacting a thiourethane resin, an alcohol, and an optional component under high temperature and high pressure conditions to produce a polythiol compound and an optional urethane compound as the polythiol composition.

[0056] (Resin mixture containing thiourethane resin) The process for producing the polythiol composition may involve contacting a resin mixture containing a thiourethane resin with an alcohol and an optional component under high temperature and high pressure conditions, thereby reacting the thiourethane resin in the resin mixture with the alcohol and the optional component under high temperature and high pressure conditions to produce the polythiol composition.

[0057] The resin mixture containing thiourethane resin further contains components other than thiourethane resin. Other components besides thiourethane resin include resins other than thiourethane resin, and inorganic materials for lens fabrication (e.g., glass).

[0058] Other than thiourethane resin, there are no particular restrictions, and examples include: a hybrid material of thiourethane resin and urethane resin produced by adding polyol to the raw materials when manufacturing thiourethane resin; a hybrid material of thiourethane resin and urea resin produced by adding a polyamine compound to the raw materials when manufacturing thiourethane resin; a polyolefin film to protect the surface of a resin molded body for eyeglass lens manufacturing; a hard coat or primer coat to protect the surface of a resin molded body for eyeglass lens manufacturing; an abrasive used when polishing a resin molded body for eyeglass lens manufacturing; a resin material for fixing a resin molded body when cutting a resin molded body for eyeglass lens manufacturing; and tape or tape adhesive used to fix a glass mold used when creating a resin molded body for eyeglass lens manufacturing. There are no particular limitations on specific examples of resins other than thiourethane resin, but for example, urethane resin is a preferred example.

[0059] It is preferable that the resin mixture containing thiourethane resin is recovered during at least one of the following processes: the manufacturing process of eyeglass lenses, the manufacturing process of eyeglasses, and the disposal process of eyeglasses. The manufacturing process for eyeglass lenses, the manufacturing process for eyeglasses, and the disposal process for eyeglasses are as described above. The resin mixture containing thiourethane resin preferably contains cutting powder containing thiourethane resin.

[0060] (Reaction mixture containing a polythiol composition) The step of producing a polythiol composition may involve reacting a thiourethane resin, an alcohol, and optionally an optional component under high temperature and high pressure conditions to produce a polythiol composition, thereby obtaining a reaction mixture containing the target polythiol composition. The reaction mixture may contain a polythiol composition as the main product and other components other than the polythiol composition. Other components in the reaction mixture besides the polythiol composition include by-products, the aforementioned reaction solvent, residues of the raw materials (thiourethane resin, alcohol, optional components), and impurities contained in the raw materials.

[0061] [[Separation process]] A method for producing a polythiol composition may include a separation step of separating the target polythiol composition from a reaction mixture containing the above-mentioned polythiol composition. There are no particular restrictions on the separation method in the separation process, and known methods include filtration, decantation, extraction, distillation, drying (including vacuum drying), and purification (e.g., column chromatography). These may be used individually or in combination of two or more methods.

[0062] The separation step preferably includes filtering the reaction mixture containing the polythiol composition obtained in the reaction step to obtain a filtrate containing the polythiol composition. According to this embodiment, it is easier to remove solids contained in the reaction mixture.

[0063] Methods for separating polythiol compounds in a polythiol composition include extraction with an organic solvent or inorganic solvent capable of dissolving the polythiol compounds. Common purification methods for polythiol compounds include column purification, distillation purification, recrystallization purification, and salt extraction.

[0064] A method for separating urethane compounds in a polythiol composition is to extract them with an organic solvent or inorganic solvent capable of dissolving the urethane compounds. Common purification methods for urethane compounds include column purification, distillation purification, recrystallization purification, and salt extraction.

[0065] If the step for producing the polythiol composition is the step for producing the polythiol compound and the urethane compound as described above, the separation step preferably includes at least one of the following: filtering the reaction mixture containing the polythiol compound and the urethane compound to obtain a filtrate containing the polythiol compound as the filtrate, and obtaining a mixture containing the urethane compound as the filtrate.

[0066] If the separation step includes obtaining a filtrate containing a polythiol compound as the filtrate, the polythiol compound as a polythiol composition can be obtained by separating the polythiol compound from the filtrate.

[0067] [[Other processes]] The method for producing the polythiol composition may include other steps besides those described above, if necessary. Other processes include, for example, classification, sieving, washing, and crushing (grinding) processes.

[0068] <Classification process> A method for producing a polythiol composition may further include a classification step, prior to the reaction step for producing the polythiol composition, in which cutting powder containing a thiourethane resin is classified to obtain a powder containing a thiourethane resin with a smaller average particle size (for example, the average number of circle equivalent diameters) than the aforementioned cutting powder (i.e., cutting powder with a reduced average particle size).

[0069] In the reaction step for producing the polythiol composition, which includes this classification step, the powder, the alcohol, and the optional component are brought into contact under high temperature and high pressure conditions, thereby reacting the thiourethane resin in the powder with the alcohol and the optional component under high temperature and high pressure conditions. If the method for producing the polythiol composition includes a classification step, the reaction step involves contacting a powder consisting of particles with a small particle size (i.e., average particle diameter), the alcohol, and the optional component under high temperature and high pressure conditions. This makes it possible to further improve the reaction efficiency between the thiourethane resin in the powder, the alcohol, and the optional component.

[0070] Examples of average particle diameters include the number-average particle diameter. Examples of particle size include the equivalent diameter of a circle. Classification methods include sieving and centrifugation. For details on the sieving process used for classification, please refer to the sieving process described below.

[0071] <Sieving process> The method for producing the polythiol composition may include a sieving step before the reaction step for producing the polythiol composition, in which cutting powder containing thiourethane resin is sieved to obtain powder containing thiourethane resin that has passed through the sieve (i.e., cutting powder that has passed through the sieve). In the reaction step for producing the polythiol composition, which includes this sieving step, the powder, the alcohol, and the optional component are brought into contact under high temperature and high pressure conditions, thereby reacting the thiourethane resin in the powder with the alcohol and the optional component under high temperature and high pressure conditions. If the method for producing the polythiol composition includes a sieving step, the reaction step involves contacting a powder consisting of small particles with the alcohol and the optional component under high temperature and high pressure conditions, thereby improving the reaction efficiency between the thiourethane resin, the alcohol, and the optional component.

[0072] There are no particular restrictions on the above sieve. The nominal mesh opening of the sieve as defined in JIS Z-8801-1:2019 is, for example, 0.1 to 20 mm, preferably 0.1 to 10 mm, more preferably 0.1 to 5 mm, even more preferably 0.1 to 2 mm, even more preferably 0.3 to 2 mm, and particularly preferably 0.5 to 1.5 mm.

[0073] <Washing Process> The method for producing the polythiol composition may include a washing step in which the thiourethane resin powder (i.e., powder containing thiourethane resin) is washed with a hydrocarbon having 5 to 12 carbon atoms as a washing solvent, prior to the reaction step for producing the polythiol composition. In the reaction step for producing the polythiol composition, which includes this washing step, the powder washed in the washing step, the alcohol, and the optional component are brought into contact under high temperature and high pressure conditions, thereby reacting the thiourethane resin in the powder with the alcohol and the optional component under high temperature and high pressure conditions. This results in a polythiol composition with a higher purity of the polythiol component as the main component. In particular, when using cutting powder containing thiourethane resin as a starting material in the method for producing a polythiol composition, the above-mentioned cleaning step can effectively remove oil from the cutting machine adhering to the cutting powder, thereby obtaining a polythiol composition with a higher purity of the polythiol component as the main component.

[0074] The hydrocarbon used as the washing solvent may be used alone or in combination of two or more types. The preferred embodiment of the hydrocarbon as a washing solvent is the same as the preferred embodiment of the hydrocarbon as a reaction solvent described above. However, the reaction solvent and the washing solvent may be the same or different.

[0075] There are no particular restrictions on the cleaning method in the cleaning process; known methods such as adding the above-mentioned cleaning solvent to the thiourethane resin powder and mixing it can be applied.

[0076] When the method for producing the polythiol composition includes the aforementioned sieving step and washing step, it is preferable to perform the sieving step and washing step in that order. In this case, there is no need to wash the cutting powder that did not pass through the sieve, so the amount of washing solvent used can be further reduced.

[0077] <Crushing (Mashing) Process> The method for producing the polythiol composition may include a crushing (grinding) step of crushing and / or grinding the thiourethane resin before the reaction step that produces the polythiol composition. There are no particular restrictions on the crushing (grinding) method in the crushing (grinding) process, and known methods can be applied. [Examples]

[0078] The present disclosure will be further described below with reference to examples. However, the present disclosure is not limited to the embodiments shown in the examples.

[0079] [Manufacturing Example 1] <Manufacturing of molded articles containing thiourethane resin> In a flask equipped with a stirring device, dimethyltin dichloride (0.0075 parts by mass per 100 parts by mass of the total amount of the polyisocyanate compound and the polythiol composition below), JP-506H (manufactured by Johoku Kagaku Kogyo Co., Ltd.; acidic phosphate ester) (0.15 parts by mass per 100 parts by mass of the total amount of the polyisocyanate compound and the polythiol composition below), and m-xylylene diisocyanate (XDI) (49.6 parts by mass), a polyisocyanate compound, were added. After stirring until all additives were sufficiently dissolved, a polythiol composition (50.4 parts by mass) mainly composed of 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, and 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane was added and mixed to obtain a polymerizable composition, which is a transparent, homogeneous solution. This polymerizable composition was degassed at 300 Pa for 30 minutes or more, and then filtered through a polytetrafluoroethylene (PTFE) filter with a pore size of 5 μm. Subsequently, it was injected into a mold consisting of a glass mold and gasket having the desired lens shape. The mold into which the polymerizable composition was injected was polymerized in an oven for 24 hours at a temperature range of 10°C to 120°C, depending on the shape of the lens. The mold was removed from the oven and demolded to obtain a spectacle lens molded from an optical component resin. The obtained molded body was annealed at 120°C for 2 hours.

[0080] <Manufacturing of thiourethane resin powder> Lenses were manufactured by machining the molded body obtained above. The resulting machining dust was collected and passed through a sieve with a nominal mesh size of 1 mm as specified in JIS Z-8801-1:2019 to obtain thiourethane resin powder (i.e., powder containing thiourethane resin) that passed through the sieve.

[0081] [Example 1] 5.0 g of thiourethane resin powder obtained in Production Example 1 was placed in a pressure-resistant reactor, 20 g of anhydrous methanol was added, and the reactor was sealed. A TVS-N2-200 portable reactor (stainless steel, internal volume 200 mL) manufactured by Pressure Glass Industry Co., Ltd. was used as the pressure-resistant reactor. After replacing the inside of the container with CO2 gas, CO2 gas was further introduced until the internal pressure reached the predetermined initial pressure of 2.0 MPa. The pressure-resistant reactor was heated to 190°C (reaction temperature in Table 1) using a band heater, and the heating and pressurizing were maintained for 4.0 hours (reaction time in Table 1). The pressure after heating to 190°C was 5.9 MPa (reaction pressure in Table 1). Subsequently, the reaction vessel was rapidly cooled to room temperature using ice water (3 minutes to 100°C, with ice water replaced as needed for a total of about 30 minutes). After the temperature had fallen below room temperature, the CO2 gas was released from the reaction vessel to return to atmospheric pressure. The extracted reaction product separated into two layers: an upper layer of alcohol and a lower layer of oil. The upper layer of alcohol was transferred to a separate beaker, and the oil layer was washed three times with anhydrous methanol. Next, 2.3 g of the alcohol-insoluble component from the oil layer was dried under reduced pressure and weighed to obtain a reaction mixture containing the polythiol composition. The reaction mixture obtained in the above reaction step was subjected to column chromatography using chloroform as the developing solvent (TLC; developing solvent: chloroform, detection reagent: phosphomolybdate ethanol solution), and spots with an Rf value of around 0.7 were isolated to obtain a chloroform solution of the polythiol composition. From the obtained chloroform solution, chloroform was removed by distillation using a rotary evaporator, and low-boiling point components were removed using a vacuum pump to obtain 1.31 g (yield: 52.0% by mass) of a polythiol composition mainly composed of 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, and 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane (i.e., polythiol components). The yield values ​​for "Polythiol Composition" in Table 1 were calculated by dividing the mass of the polythiol composition, which is the main component of the thiourethane resin, by the theoretical yield, and then dividing the "mass of polythiol composition" obtained in the above reaction step in Table 1 by the theoretical yield, and finally expressing the resulting value as a percentage.

[0082] [Examples 2-9 and 12, and Comparative Example 3] In Example 1, instead of using 5.0 g of thiourethane resin, 20 g of solvent, methanol as the type of anhydrous alcohol used as the solvent, a reaction temperature of 190°C, a reaction pressure of 5.9 MPa, and a reaction time of 4.0 hours, the same procedure as in Example 1 was carried out, except that the mass of the thiourethane resin, the mass of the solvent, the type of anhydrous alcohol used as the solvent, the reaction temperature, the reaction pressure, and the reaction time were changed as shown in Table 1. The mass of the alcohol-insoluble component, as well as the mass and yield of the obtained polythiol composition, are shown in Table 1.

[0083] [Example 10] In Example 1, the procedure was the same as in Example 1, except that air was used and the reaction pressure was 2.9 MPa instead of CO2 gas and a reaction pressure of 5.9 MPa. The mass of the alcohol-insoluble component, as well as the mass and yield of the obtained polythiol composition, are shown in Table 1.

[0084] [Example 11] In Example 2, the procedure was the same as in Example 2, except that air was used and the reaction pressure was 2.9 MPa instead of CO2 gas and 6.1 MPa. The mass of the alcohol-insoluble component, as well as the mass and yield of the obtained polythiol composition, are shown in Table 1.

[0085] [Comparative Example 1] In Example 1, instead of using 5.0 g of thiourethane resin, carbon dioxide, 20 g of solvent, anhydrous methanol as the solvent, a reaction temperature of 190°C, a reaction pressure of 5.9 MPa, and a reaction time of 4.0 hours, the reaction process was carried out using 15.0 g of thiourethane resin, monoethanol, 180 g of solvent, toluene as the solvent, a reaction temperature of 110°C, a reaction pressure of 0.1 MPa, and a reaction time of 6.0 hours. The same procedure as in Example 1 was followed. The mass of the alcohol-insoluble component, as well as the mass and yield of the obtained polythiol composition, are shown in Table 1.

[0086] [Comparative Example 2] In Example 1, the reaction was carried out using 0.5 g of thiourethane resin, water as the solvent, a reaction pressure of 6.0 MPa, and a reaction time of 6.0 hours, instead of using 5.0 g of thiourethane resin, anhydrous methanol as the solvent, a reaction pressure of 5.9 MPa, and a reaction time of 4.0 hours. The same procedure as in Example 1 was followed. The mass of the alcohol-insoluble component, as well as the mass and yield of the obtained polythiol composition, are shown in Table 1.

[0087] [Table 1]

[0088] As can be seen from Table 1 above, the methods for producing polythiol compositions in Examples 1 to 12, which include a reaction step of reacting a thiourethane resin with an alcohol under high temperature and high pressure conditions to produce a polythiol composition, allow for the production of a polythiol composition without the need for a neutralization process. As can be seen from Table 1, the yield of the polythiol composition in Example 1 is 52.0% by mass, indicating that among Examples 1 to 12, Example 1 (reaction temperature 190°C, reaction pressure 5.9 MPa, reaction time 4.0 hours) is the most preferred example.

[0089] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended. This disclosure may arbitrarily combine the examples, contents, and various physical properties of each of the above components described in the detailed description of the invention as examples or preferred ranges. Furthermore, by adjusting the compositions described in the examples to match those described in the detailed description of the invention, the disclosed embodiments can be implemented in the same manner as the examples across the entire claimed composition range.

Claims

1. A method for producing a polythiol composition, comprising a reaction step of reacting a thiourethane resin with an alcohol under high temperature and high pressure conditions to produce a polythiol composition.

2. A method for producing a polythiol composition according to claim 1, wherein the reaction temperature under the above reaction conditions is greater than 130°C and 270°C or less.

3. A method for producing a polythiol composition according to claim 1 or 2, wherein the reaction pressure under the aforementioned reaction conditions is 2.0 MPa or more and less than 22.0 MPa.

4. A method for producing a polythiol composition according to claim 1 or 2, wherein the reaction time under the above reaction conditions is 0.3 to 20 hours.

5. The method for producing the polythiol composition according to claim 1 or 2, wherein the alcohol has 1 to 20 carbon atoms.

6. The method for producing a polythiol composition according to claim 1 or 2, wherein the alcohol is at least one selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol, t-butanol, 1-octanol, 2-octanol, benzyl alcohol, and 2-hexyl-1-decanol.

7. A method for producing a polythiol composition according to claim 1 or 2, wherein the reaction step is carried out under a carbon dioxide atmosphere.

8. A method for producing the polythiol composition according to claim 1 or 2, wherein the polythiol composition comprises at least one selected from the group consisting of 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, and 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane.

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