Method for preparing sulfur copolymers

Abstract

Methods for preparing sulfur copolymers, sulfur copolymers, and polymer compositions comprising one or more sulfur copolymers are provided. The methods include preparing a sulfur copolymer represented by formula (I): [Formula 1] JPEG2024510848000025.jpg37170[In the formula, R 1 and R 2 are each independently hydrogen, C1-C 18 C1-C substituted with alkyl, halogen or interrupted by O or S 18 Alkyl; C1-C4 alkyl, C1-C4 alkoxy, C1-C4 alkylthio or C6-C substituted with halogen 18 Aryl or C6-C 12 is aryl] with elemental sulfur in the presence of a polymerization initiator.

Description

[Technical field]

[0001] The present invention relates to a method for preparing sulfur copolymers by copolymerizing a five-membered ring monothiocarbonate compound with elemental sulfur in the presence of a polymerization initiator, to sulfur copolymers obtainable by said method, and to compositions comprising one or more sulfur copolymers. [Background technology]

[0002] Sulfur plays a vital role in many applications within the chemical industry.

[0003] Vulcanization of rubber is made possible by the use of sulfur as a crosslinking agent. Sulfur in its polymeric form is used as a rubber vulcanizing agent under the trade name Crystex (Eastman).

[0004] Organic polysulfides are the sulfur source of choice because they are excellent vehicles for transporting sulfur to reaction sites. G. Carroll, Phosphorus, Sulfur and Silicon, 1994, 95-96, 517-518, describes various uses of polysulfides.

[0005] For example, polysulfides are used in the lubricants industry to form a protective layer on metal surfaces to prevent them from welding under extreme load conditions. The advantage of their use as extreme pressure agents is that they contain no olefins, no chlorine, and no colour forming trithiones.

[0006] In the petroleum industry, dimethyl disulfide is sometimes used as a presulfiding agent to extend the life of metal oxide-based catalysts. In the oil and gas industry, dimethyl disulfide is also sometimes used as a sulfur solvent.

[0007] JJGriebel et al., Progr. Polym. Sci., 58, 2016, 90-125, describe sulfur-containing polymeric materials derived from S8 with a high degree of sulfur catenation, i.e., high SS bond rank in the polymer structure. Polysulfides, a class of polymers with high sulfur content, are structurally similar to polymeric sulfur but have improved stability and processability. Synthesis of polysulfides directly from elemental sulfur can be achieved by condensation reactions, free radical reactions, and ionic copolymerization reactions.

[0008] Polysulfide rubbers are polycondensation products of organic dihalides and alkaline polysulfides, known for example under the trade name Thiokol, and are used as elastomers for sealants. They may be liquid polymers, optionally crosslinked by oxidizing the SH groups at the polymer ends to disulfide bonds.

[0009] The anionic copolymerization of propylene sulfide with elemental sulfur initiated with sodium thiophenoxide is described, for example, in A. Duda et al., Macromolecules, 1982, 15, 36-40. Copolymers with sulfur contents up to 85% by weight, i.e., -[CH2CH(CH3)S z ]-, copolymers with average z up to 8 are described.

[0010] A. Duda et al., Macromol. Chem., Rapid Commun., 1988, 9, 151-157, reported that the anionic cooligomerization of S8 with cyclic sulfides in the presence of symmetric bis(hydroxyalkyl) polysulfides resulted in number-average M n It is described that this results in liquid α,ω-oligodiols with a molecular weight of 700 to 2500 g / mol and containing up to 80 wt. % chemically bound sulfur.

[0011] Cationic bulk copolymerization is known by M. Schmidt et al., Angew. Chem. Int. Ed., 1978, 17, 51-52, by ring-opening of cyclic sulfur-containing comonomers using Lewis acids to give linear polysulfides.

[0012] The use of S8 as a reaction medium and comonomer in a process termed inverse vulcanization has also been described by J. J. Griebel et al., Progr. Polym. Sci., 58, 2016, 90-125, for example using 1,3-diisopropenylbenzene in bulk copolymerization with S8 to provide the statistical copolymer poly(sulfur-random-(1,3-diisopropenylbenzene)).

[0013] US 2014 / 0199592 A1 discloses polymeric compositions comprising copolymers of sulfur and one or more monomers such as diisopropenyl-benzene or propylene sulfide. For example, the preparation of sulfur / propylene sulfide copolymers using thioacyl transfer polymerization is described, using benzyl dithiobenzoate as initiator and tetraphenylphosphonium chloride in toluene to give a pale red oily polymer.

[0014] US Patent No. 5,929,202A discloses a process for preparing ethylene sulfide / sulfur copolymers by polymerizing ethylene sulfide with sulfur in the presence of a polymerization initiator, such as an aliphatic tertiary amine such as DABCO (1,4-diazabicyclo[2.2.2]octane) or tetrabutylammonium acetate, and a solvent. The copolymers are described as being useful as vulcanizing agents and vulcanization accelerators for tire-quality rubber, or as industrial elastomers. However, the use of ethylene sulfide or propylene sulfide is avoided due to their poor storage stability.

[0015] Incorporating a high content of S-S bonds into polymers provides an avenue to materials with favorable properties since such moieties are redox active, highly polarizable, confer high refractive index, and exhibit dynamic covalent bonding. Thus, organic polysulfides play an important role in various industries.

[0016] Many of the preparation processes to obtain organic polysulfides have drawbacks: for example, halogenated precursors pose a risk of halogen contamination of the product; the use of olefins poses a risk of olefin residues in the product; in the case of episulfide-derived polysulfides, the synthesis is based on high-energy starting materials that are generally not available.

[0017] Thus, there remains a need for readily accessible synthetic routes to organosulfur polymers that enable industrially viable production.

[0018] Further, there is a need for readily available copolymers having desirable and tunable sulfur content that are suitable for use in optical applications, in sealant applications, for immobilizing sulfur in polymer matrices, as metal working fluids, and / or as active materials in Li-S batteries. Summary of the Invention [Problem to be solved by the invention]

[0019] It is therefore an object of the present invention to provide a method for preparing sulfur copolymers that is economical and flexible.

[0020] It is a further object of the present invention to provide a method for preparing sulfur copolymers using S-containing monomers that have improved storage stability compared to ethylene sulfide or propylene sulfide.

[0021] It is a further object of the present invention to provide sulfur copolymers that have a high refractive index and are suitable for use, for example, in optical applications.

[0022] It is a further object of the present invention to provide a sulfur copolymer having a high sulfur content and / or high viscosity, suitable for use, for example, as a metalworking fluid. [Means for solving the problem]

[0023] It has now been found that sulfur copolymers can be easily prepared by reacting cyclic monothiocarbonate compounds with elemental sulfur in the presence of a polymerization initiator.In particular, the process of preparing sulfur copolymers makes it possible to easily obtain copolymers with desired sulfur content, which can be adjusted, and thus suitable for use in optical applications, sealant applications, sulfur immobilization in polymer matrices, metalworking oils, and / or active materials in Li-S batteries.

[0024] Thus, in a first aspect, the present invention relates to a process for preparing a sulfur copolymer, the process comprising the steps of: [ka] [In the formula, R 1 and R 2 are each independently hydrogen, C1-C 18 C1-C substituted with alkyl, halogen or interrupted by O or S 18 Alkyl; C1-C4 alkyl, C1-C4 alkoxy, C1-C4 alkylthio or C6-C substituted with halogen 18 Aryl or C6-C 12 is aryl] with elemental sulfur in the presence of at least one polymerization initiator.

[0025] In a further aspect, the present invention relates to a sulfur copolymer obtainable by the process described in any of the aspects herein.

[0026] In a further aspect, the present invention provides a compound of formula [ka] The sulfur copolymer contains n alkylene units and (n+1) polysulfide units, and the polysulfide units contain a total of (2n+1) to (2n+9) sulfur atoms, n is 1 or greater, and R 1 and R 2 is as described in any of the embodiments herein.

[0027] In a further aspect, the present invention relates to a polymer composition comprising one or more of the sulfur copolymers described in any of the aspects herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] The terms alkyl, alkoxy, alkylthio, aryl, halogen are art-recognized and generally have the following meanings, unless said groups are further specified in specific embodiments below.

[0029] Alkyl, e.g. C1-C 18 Alkyl, C1-C8 alkyl or C1-C4 alkyl may be linear or branched, where possible, within the limits of the given carbon atoms. Examples are methyl (Me), ethyl (Et), n-propyl, isopropyl, n-butyl, 1-methylpropyl, 2-methylpropyl, t-butyl, n-pentyl, 2-pentyl, 3-pentyl, 2,2-dimethylpropyl, n-hexyl, 1-methylhexyl, n-heptyl, 1,1,3,3-tetramethylbutyl, 1-methylheptyl, 3-methylheptyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl and structural isomers of the above mentioned n-alkyl radicals.

[0030] Any alkyl group of several carbon atoms, especially more than two carbon atoms, or such an alkyl moiety that is part of another moiety, may be interrupted by a heterofunctional group such as -O- or -S-. They may be interrupted by one or more of these heterofunctional groups, one group in each case generally inserted in one CC-bond of the alkyl group. If the interrupted group is further substituted, the substituent is generally not at a heteroatom. If there are two or more interrupted groups of -O- or -S- type in one radical, they are generally identical.

[0031] Alkoxy, such as C1-C4 alkoxy, is alkyl-O.

[0032] Alkylthio, for example C1-C4 alkylthio, is alkyl-S.

[0033] Aryl, e.g. C6-C 18 Aryl or C6-C 12 Aryl may be, within the limits of a given carbon atom, phenyl, fluorenyl, biphenylyl, terphenylyl or naphthyl, which may have a fused ring, such as indanyl. Preferred examples are phenyl, 1-naphthyl, 2-naphthyl, 3- or 4-biphenylyl. Each aryl may be unsubstituted or substituted one or more times.

[0034] Halogen (Hal) represents I, Br, Cl or F, preferably Cl in alkyl and Cl or Br in aryl.

[0035] Substituent “C 12 / 14 " is C 12 / C 14 It means a substituent derived from a fatty alcohol.

[0036] The term "substituted" means "single or multiple substituted", i.e., substituted one to three times, preferably one or two times, and more preferably one time, if possible. If a substituent is present more than once in a group, it may be different at each occurrence.

[0037] As used herein, the term "sulfur copolymer" includes oligomers and polymers, i.e., having at least two polysulfide units and at least one alkylene unit, provided that at least one S-S bond is present. [ka] or formula [ka] are not included in the definition of sulfur copolymer.

[0038] As used herein, the term "polysulfide unit" includes thioether groups and polysulfide groups of at least two sulfur atoms (S2).

[0039] As used herein, the singular articles "a," "an," and "the" include the plural unless the content clearly dictates otherwise.

[0040] Typically, the process provides a mixture of one or more sulfur copolymers.

[0041] Thus, in a further aspect, the present invention relates to a process for preparing a polymer composition comprising one or more sulfur copolymers, the process comprising the steps of: [ka] [In the formula, R 1 and R 2 are each independently hydrogen, C1-C 18 C1-C substituted with alkyl, halogen or interrupted by O or S 18Alkyl; C1-C4 alkyl, C1-C4 alkoxy, C1-C4 alkylthio or C6-C substituted with halogen 18 Aryl or C6-C 12 is aryl] with elemental sulfur in the presence of at least one polymerization initiator.

[0042] In one preferred aspect, the present invention relates to a process for preparing a sulfur copolymer, comprising: R 1 and R 2 are each independently hydrogen, C1-C4 alkyl, C1-C substituted with halogen or interrupted by O or S. 18 Alkyl; C6~C 12 Aryl, or C6-C substituted with C1-C4 alkyl, C1-C4 alkoxy, C1-C4 alkylthio or halogen 12 It is aryl.

[0043] The cyclic monothiocarbonate compound of formula (I) is represented by the formula [ka] [In the formula, R 2 is hydrogen, C1-C4 alkyl, C1-C8 alkyl substituted with halogen or interrupted by O or S; or phenyl. More preferably, it is a process for preparing a sulfur copolymer which is a cyclic monothiocarbonate compound of the formula:

[0044] Thus, in a more preferred aspect, the present invention relates to a process for preparing a sulfur copolymer, comprising: R 1 is hydrogen and R 2 is hydrogen, C1-C4 alkyl, C1-C8 alkyl substituted with halogen or interrupted by O or S; or phenyl.

[0045] Preferred are cyclic monothiocarbonate compounds of formula (V) reacted in the present process, where R 2 is hydrogen or C1-C4 alkyl, C1-C8 alkyl substituted with halogen or interrupted by O.

[0046] More preferred are cyclic monothiocarbonate compounds of formula (V) reacted in the present process, where R 2 is hydrogen, C1-C4 alkyl, or C1-C6 alkyl interrupted by O.

[0047] 1. A process for preparing a sulfur copolymer, comprising: R 1 is hydrogen and R 2 Particularly preferred is the process wherein is hydrogen or C1-C4 alkyl.

[0048] 1. A process for preparing a sulfur copolymer, comprising: R 1 is hydrogen and R 2 is C1-C4 alkyl.

[0049] Suitable examples of the cyclic monothiocarbonate compound of formula (V) include compounds represented by the formula [ka] Examples of cyclic monothiocarbonates include the following:

[0050] One or more compounds of formula (I), preferably one or more compounds of formula (V), can be used in the process of the invention.

[0051] Preferred is a process utilizing one compound of formula (I), preferably one compound of formula (V).

[0052] Particularly preferred is the process using one compound of formula (Vb).

[0053] Likewise preferred is a process using a mixture of two different compounds of formula (I).More preferred is a process using a mixture of two different compounds, the mixture comprising a compound of formula (Va) or a compound of formula (Vb).

[0054] More preferred is a process using a mixture of a compound of formula (Va) and a compound of formula (Vb).More preferred is a process using a compound of formula (Vb) in an amount of more than 50% by weight based on the total weight of the mixture of the compound of formula (Va) and the compound of formula (Vb).

[0055] The cyclic monothiocarbonate compounds of formula (I) or formula (V) may be prepared according to the processes described in US Pat. No. 3,072,676, US Pat. No. 3,201,416 or WO 2019 / 034469 A1.

[0056] Typically, the cyclic monothiocarbonate compounds of formula (I) are liquid at 21° C. and 1 bar. In cases where the cyclic monothiocarbonate compounds of formula (I) are solid at 21° C. and 1 bar, said compounds can be applied in a molten form that is stable at the polymerization temperature.

[0057] Suitable sulfur sources may be sulfur recovered from hydrogen sulfide as raw material generated from petroleum refining processes or naturally occurring sulfur. Suitable sulfur may be sublimed sulfur, precipitated sulfur, flowers of sulfur and colloidal sulfur.

[0058] Elemental sulfur may be provided in powder form. Under ambient conditions, elemental sulfur exists primarily in the form of eight-membered rings (S8) and melts at temperatures ranging from 120-124°C and above 159°C undergoes equilibrium ring-opening polymerization of S8 monomers to linear polysulfanes with diradical chain ends.

[0059] S8 is typically used in the process as it is the most stable and inexpensive raw material. However, many of the other sulfur allotropes may be used, including other cyclic allotropes that can be derived by melt heat treatment of S8. Any sulfur species that, when heated, results in diradically or anionically polymerizing species may be used in the process.

[0060] Generally, the process for preparing the sulfur copolymer is carried out by copolymerizing the cyclic monothiocarbonate compound of formula (I) with elemental sulfur in the presence of a polymerization initiator.

[0061] Essentially any type of polymerization initiator may be used to initiate the reaction, typically those that can be used for anionic, cationic or coordination polymerization. It is preferred to use an anionic polymerization initiator.

[0062] Examples of anionic polymerization initiators include amine-containing bases, organic phosphine compounds, metal salts of mercapto compounds, metal alcoholates, and basic inorganic compounds, preferably basic inorganic salts.

[0063] Examples of amine-containing bases include compounds having a tertiary amino group, a guanidino group, or an amidine group.

[0064] Examples of compounds having a tertiary amino group include trimethylamine, triethylamine, tributylamine, 2,4,6-tris(dimethylaminomethyl)phenol, pyridine, 1,4-diazabicyclo[2.2.2]octane (DABCO), tetramethylethylenediamine, and dimethylaminopyridine (DMAP).

[0065] An example of a compound having a guanidino group is guanidino(1,5,7-triazabicyclodocene (TBD)).

[0066] Examples of compounds having an amidine group include diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) and N-methyl-1,5,7-triazabicyclododecene (MTBD).

[0067] Examples of organophosphine compounds include triphenylphosphine or tributylphosphine.

[0068] An example of a metal alcoholate is sodium methoxide.

[0069] Examples of metal salts of mercapto compounds include sodium thiomethoxide, sodium thiophenoxide, or the sodium salt of 2-mercaptobenzothiazole.

[0070] An organic thiol compound, such as monomercaptan, dimercaptan or polymercaptan, may be added as an initiator in the copolymerization reaction. The thiol compound may usually be added together with an organic base, such as a compound having an amine or amidine group, such as DBU, DBN or MTBD. The thiol compound may be introduced so that it is retained as a covalent part of the copolymer.

[0071] Examples of suitable monothiol compounds include C1-C 12 Alkyl mercaptans and aryl mercaptans such as thiophenol.

[0072] Examples of suitable dithiol compounds include 1,2-dimercaptoethane, 2,2-dimercaptopropane, 1,3-dimercaptopropane, 1,4-dimercaptobutane, 1,6-dimercaptohexane, tetra(ethylene glycol)dithiol, 3,6-dioxa-1,8-octane-dithiol, 2,2'-thiodiethanethiol, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 5 ... mercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 1,1,3,3-tetrakis(mercaptomethylthio)propane, 1,2-bis(2-mercaptoethylthio)ethane, 1,5-dimercapto-3-oxapentane, 2,2-dimethylpropane-1,3-dithiol, 2-mercaptomethyl-1,3-dimercaptopropane, benzenedimethanethiol (isomers), (1,1'-bihenyl)-4,4'-dimethanethiol, 2-mercaptoethyl-ether, dimercaptobenzene (isomers) ), terphenyldithiol, 1,4-bis(mercaptomethyl)cyclohexane, 1,4-dimercaptocyclohexane, bis(4-mercaptophenyl)sulfide, bis(4-mercaptophenyl)ether, 2-mercaptomethyl-1,4-dimercaptopropane, 2-(2-mercaptoethylthio)-1,3-dimercaptopropane, 1,2-bis(2-mercaptoethylthio)-3-mercaptopropane, ethylene glycol dithioglycolate, ethylene glycol bis(2-mercaptoacetate), ethylene glycol Lithium ion bis(3-mercaptopropionate), 1,4-butanediol bis(2-mercapto-acetate), 1,4-butanediol bis(3-mercaptopropionate), 2,5-bis(mercaptomethyl)-1,4-dithiane, 2,5-bis(mercaptoethyl)-1,4-dithiane, 2,2-bis(4-mercaptophenyl)propane, bis(4-mercaptomethylphenyl)sulfide, bis(4-mercaptomethylphenyl)ether, and 2,2-bis(4-mercaptomethylphenyl)propane.

[0073] Examples of suitable trithiol compounds include 1,3,5-trimercaptobenzene, 1,3,5-tris(mercaptomethyl)benzene, trimethylolpropane-tri(3-mercaptopropionate), trimethylolpropane-tris(thioglycolate), 1,2,3-trimercaptopropane, trimethylolpropane-tris(2-mercaptoacetate), trimethylolpropane-tris(3-mercaptopropionate), and 1,1,1-tris(mercaptomethyl)propane.

[0074] Examples of suitable tetrathiol compounds include pentaerythritol-tetrakis(thioglycolate), pentaerythritol-tetrakis(2-mercaptoacetate), pentaerythritol-tetrakis(3-mercaptopropionate), 1,1,3,3-tetrakis(mercaptomethylthio)propane, and tetrakis(mercaptomethyl)methane.

[0075] The organic thiol compound may be added to the copolymerization reaction in an amount of up to 10% by weight, preferably up to 5% by weight, based on the total weight of elemental sulfur and the cyclic monothiocarbonate compound of formula (I).

[0076] Examples of basic inorganic compounds are basic zeolites, metal oxides, metal hydroxides, metal sulfides including ammonium sulfide, hydrotalcites and basic clays.

[0077] The basic inorganic compound is preferably an inorganic salt selected from a metal hydroxide, a metal sulfide, an ammonium sulfide, a metal hydrogen sulfide, a metal oxide, a metal phosphate, or a metal silicate. p ) 2- where p is an integer of at least 1 to 10. The term "hydrogen sulfide" includes monosulfides, oligosulfides, and polysulfides of the formula (HS q ) 1- (wherein q is an integer of at least 1 to 10) are included.

[0078] More preferably, the basic inorganic compound is an inorganic salt selected from metal hydroxides, metal sulfides, ammonium sulfide, or metal hydrogen sulfide salts. The cation of the inorganic salt is preferably a cation having one or two positive charges, such as an alkali cation or an alkaline earth cation, more preferably an alkali cation such as sodium or potassium.

[0079] Particularly preferred examples of inorganic salts are NaOH, KOH, NaSH, (NH4)2S. p , Na2S p , and K2S p (wherein p is 1 to 10).

[0080] Examples of the cationic polymerization initiator include Lewis acids such as titanium tetrachloride, aluminum chloride, and boron trifluoride diethyl ether complex.

[0081] Examples of the coordination polymerization initiator include metal compounds such as diethylzinc, zinc acetate, triethylaluminum, zinc dimethyldithiocarbamate, and zinc diethyldithiocarbamate.

[0082] The polymerization initiator is preferably an anionic polymerization initiator selected from the group consisting of amine-containing bases, organic phosphine compounds, metal salts of mercapto compounds, and basic inorganic salts.

[0083] Thus, in a preferred aspect, the present invention relates to a process for preparing a sulfur copolymer, wherein the polymerization initiator is an anionic polymerization initiator selected from the group consisting of amine-containing bases, organic phosphine compounds, metal salts of mercapto compounds, and basic inorganic salts.

[0084] More preferably, the polymerization initiator is an anionic polymerization initiator selected from the group consisting of an amine-containing base, an organophosphine compound, and a basic inorganic salt, more preferably a basic inorganic salt.

[0085] Examples of amine-containing bases are preferably compounds having a tertiary amino group, a guanidino group, or an amidine group.

[0086] Therefore, the anionic polymerization initiator is an anionic polymerization initiator selected from the group consisting of an amine-containing base selected from compounds having a tertiary amino group, a guanidino group, or an amidine group, an organic phosphine compound, and a basic inorganic salt, and the basic inorganic salt is NaOH, KOH, NaSH, (NH4)2S p , Na2S p or K2S p An anionic polymerization initiator selected from the following formula (wherein p is 1 to 10) is most preferred.

[0087] Thus, in a preferred aspect, the present invention relates to a process for preparing a sulfur copolymer, wherein the polymerization initiator is an anionic polymerization initiator selected from the group consisting of an amine-containing base, an organophosphine compound, and a basic inorganic salt, preferably a basic inorganic salt.

[0088] In a further preferred embodiment, the present invention relates to a process for preparing a sulfur copolymer, wherein the anionic polymerization initiator is a basic inorganic salt.

[0089] Polymerization initiator: NaOH, KOH, NaSH, Na2S p , (NH4)2S p , or K2S p (wherein p is 1-10) is particularly preferred.

[0090] The polymerization initiator may be used in a catalytically effective amount, for example, from 0.01 to 0.5 moles, preferably from 0.02 to 0.3 moles, based on 1 mole of elemental sulfur S8.

[0091] If desired, viscosity modifiers may be added in the process. Such viscosity modifiers are known in the art. It is preferred not to add viscosity modifiers.

[0092] The process is generally carried out under an inert atmosphere at elevated temperatures (copolymerization temperature), for example at temperatures between 40 and 230° C. The copolymerization reaction may be carried out in a solvent or without a solvent.

[0093] Thus, in a preferred aspect, the present invention relates to a process for preparing a sulfur copolymer, wherein the copolymerization step is carried out at a temperature in the range of 40 to 230°C.

[0094] When a solvent is used, the copolymerization step is generally carried out at a temperature ranging from 40 to 180°C, preferably from 60 to 160°C.

[0095] When no solvent is used, the copolymerization step is generally carried out at a temperature ranging from about 120°C to about 230°C.

[0096] The reaction time of the copolymerization step may vary from 0.5 to 8 hours, preferably from 1 to 6 hours.

[0097] Therefore, a process in which the copolymerization step is carried out in the presence of an anionic polymerization initiator at an elevated temperature for 0.5 to 8 hours is preferred, and the temperature is in the range of 40 to 180°C, particularly 60 to 160°C, when the process is carried out using a solvent, or in the range of 120 to 230°C when no solvent is used.

[0098] If present, the solvent may be an organic solvent.

[0099] Examples of suitable organic solvents are ketones such as acetone, butanone, cyclohexanone or methyl isobutyl ketone; aromatic solvents such as benzene, toluene or xylene; ethers such as tetrahydrofuran (THF), dioxane, dioxolane or dimethylethylene glycol; esters such as ethyl acetate or butyl acetate; amides such as dimethylformamide (DMF) or N-methyl-pyrrolidone (NMP); aliphatic hydrocarbons such as hexane or cyclohexane; halogen-containing solvents such as chloroform; alcohols such as ethanol, isopropanol, glycol ethers or propylene glycol monomethyl ether; and carbon disulfide. Among them, ketones, ethers and carbon disulfide are preferred. The solvents may be used individually or in combination of two or more of them.

[0100] The solvent can be used in an amount such that the raw materials elemental sulfur, polymerization initiator, and cyclic monothiocarbonate compound of formula (I) form a mixture that is 20 to 60 weight percent solids, based on the total weight of the solvent and raw materials.

[0101] The order in which the raw materials, including elemental sulfur, the monothiocarbonate compound of formula (I), the polymerization initiator, and optionally the solvent and the organic thiol compound, are charged to the reactor can be varied to affect the desired structure of the sulfur copolymer.

[0102] The mixture containing the raw materials may be a suspension, a solution, or a solid mixture at room temperature at the beginning of the reaction, depending on the types of raw materials.

[0103] For example, elemental sulfur and the cyclic monothiocarbonate compound of formula (I) may be added simultaneously or alternately to the polymerization initiator at the copolymerization temperature.

[0104] Alternatively, a portion of the elemental sulfur or the cyclic monothiocarbonate compound of formula (I) may be provided as a mixture at room temperature (approximately 20-25° C.) together with the anionic polymerization initiator. The remaining portion of the elemental sulfur or the cyclic monothiocarbonate compound of formula (I) may be added at the copolymerization temperature. It is preferred to add the elemental sulfur in molten form at the copolymerization temperature, dropwise or in small portions.

[0105] In the case where elemental sulfur is provided partially at room temperature, the mixture of the first step a) preferably comprises up to 30% by weight, more preferably up to 10% by weight, of elemental sulfur, based on the total weight of elemental sulfur.

[0106] When the cyclic monothiocarbonate compound of formula (I) is provided partially at room temperature, the mixture of the first step a) preferably comprises up to 20% by weight, more preferably up to 5% by weight, of the cyclic monothiocarbonate compound of formula (I), based on the total weight of the cyclic monothiocarbonate compound of formula (I).

[0107] The anionic polymerization initiator may be provided at room temperature or may be added prior to or simultaneously with the cyclic monothiocarbonate compound of formula (I) at the copolymerization temperature.

[0108] If desired, an organic thiol compound is added to the process, generally at room temperature or at the copolymerization temperature, either before or simultaneously with the cyclic monothiocarbonate compound of formula (I).

[0109] The cyclic monothiocarbonate compounds of formula (I) are usually added so as to effectively inhibit the homopolymerization of the resulting alkylene sulfide. The addition is usually carried out slowly, for example, dropwise or in small portions, so as to have only a small concentration of them in the reaction mixture. The rate of addition is preferably adjusted appropriately to control the formation of the resulting foam.

[0110] The cyclic monothiocarbonate compound of formula (I) may be added as a solution in a solvent, or, if the cyclic monothiocarbonate compound is in liquid form, preferably no solvent is used.

[0111] The product comprising the sulfur copolymer or one or more compositions of sulfur copolymers may be separated from the reaction mixture obtained in various ways. After cooling to room temperature, the product is usually separated from the reaction mixture to obtain the copolymer or one or more compositions comprising the copolymer, which are further processed in various applications. Such a separation step is usually carried out in a conventional manner.

[0112] Depending on the molecular weight of the resulting sulfur copolymers and their solubility in organic solvents, the products may be separated from the reaction mixture by homogenization and / or filtration. Homogenization is preferably carried out using a suitable organic solvent such as halogen-containing solvents, N-methylpyrrolidone (NMP), tetrahydrofuran (THF), toluene or carbon disulfide.

[0113] For example, the reaction mixture may be optionally filtered after homogenization. The product may be separated from the filtrate, for example by distilling off the solvent, and / or from the separated solid by washing with a suitable solvent and / or water and drying under reduced pressure. The product may be further purified by conventional means.

[0114] Suitable examples of processes for effectively carrying out the copolymerization include the following process modifications A) to H): A) A method comprising the following steps a) to d): a) providing an anionic polymerization initiator, optionally a solvent and / or an organic thiol compound; b) heating the product of step a) to a desired copolymerization temperature; c) copolymerizing the cyclic monothiocarbonate compound of formula (I) with sulfur while simultaneously or alternately adding the cyclic monothiocarbonate compound of formula (I) and elemental sulfur to form a reaction mixture comprising a copolymer; and d) Optionally, separating the copolymer from the reaction mixture.

[0115] B) A method comprising the following steps a) to d): a) providing an anionic polymerization initiator, elemental sulfur, optionally a solvent and / or an organic thiol compound; b) heating the product of step a) to a desired copolymerization temperature; c) copolymerizing the cyclic monothiocarbonate compound of formula (I) with sulfur while adding the cyclic monothiocarbonate compound of formula (I) to form a reaction mixture comprising a copolymer; and d) Optionally, separating the copolymer from the reaction mixture.

[0116] C) A method comprising the following steps a) to d). a) providing an anionic polymerization initiator, elemental sulfur, optionally a solvent and / or an organic thiol compound; b) heating the product of step a) to a desired copolymerization temperature; c) copolymerizing the cyclic monothiocarbonate compound of formula (I) with sulfur while simultaneously or alternately adding the cyclic monothiocarbonate compound of formula (I) and optionally further elemental sulfur to form a reaction mixture comprising a copolymer; and d) Optionally, separating the copolymer from the reaction mixture.

[0117] D) A method comprising the following steps a) to d). a) providing an anionic polymerization initiator, a portion of a cyclic monothiocarbonate compound of formula (I), and optionally a solvent and / or an organic thiol compound; b) heating the product of step a) to a desired copolymerization temperature; c) copolymerizing the cyclic monothiocarbonate compound of formula (I) with sulfur while simultaneously or alternately adding the remaining portion of the cyclic monothiocarbonate compound of formula (I) and elemental sulfur to form a reaction mixture comprising a copolymer; and d) Optionally, separating the copolymer from the reaction mixture.

[0118] E) A method comprising the following steps a) to d): a) providing an anionic polymerization initiator, elemental sulfur, and optionally an organic thiol compound; b) heating the product of step a) to a copolymerization temperature of at least 120°C; c) copolymerizing the cyclic monothiocarbonate compound of formula (I) with sulfur while adding the cyclic monothiocarbonate compound of formula (I) to form a reaction mixture comprising a copolymer; and d) Optionally, separating the copolymer from the reaction mixture.

[0119] F) A method comprising the following steps a) to d): a) providing elemental sulfur, optionally a solvent and / or an organic thiol compound; b) heating the product of step a) to a desired copolymerization temperature; c) copolymerizing the cyclic monothiocarbonate compound of formula (I) with sulfur, preferably while simultaneously adding the cyclic monothiocarbonate compound of formula (I) and an anionic polymerization initiator, to form a reaction mixture comprising a copolymer; and d) Optionally, separating the copolymer from the reaction mixture.

[0120] G) A method comprising the following steps a) to d): a) providing an anionic polymerization initiator, elemental sulfur, and optionally a solvent; b) heating the product of step a) to a desired copolymerization temperature; c) copolymerizing the cyclic monothiocarbonate compound of formula (I) with sulfur to form a reaction mixture comprising a copolymer, preferably while simultaneously adding the cyclic monothiocarbonate compound of formula (I) and optionally an organic thiol compound; and d) Optionally, separating the copolymer from the reaction mixture.

[0121] H) A method comprising the following steps a) to d): a) providing a solvent; b) heating the solvent to a copolymerization temperature of 40-180°C; c) copolymerizing the cyclic monothiocarbonate compound of formula (I) with sulfur, preferably simultaneously adding the cyclic monothiocarbonate compound of formula (I), elemental sulfur, an anionic polymerization initiator, and optionally an organic thiol compound, to form a reaction mixture comprising a copolymer; and d) Optionally, separating the copolymer from the reaction mixture.

[0122] Preferred examples of suitable processes for effecting copolymerization are step modifications A, B), C and E.

[0123] It is preferred that the process is carried out without the use of solvents and under an inert atmosphere, such as nitrogen or argon. Sulfur can be used in its molten form at elevated temperatures above 120° C. and can be used directly as the reaction medium.

[0124] The sulfur copolymers can be prepared by copolymerizing molten sulfur with at least one cyclic monothiocarbonate compound of formula (I). The temperatures typically used in the solvent-free process range from about 120° C. to about 230° C. The reaction time of the copolymerization step can vary from 0.5 to 8 hours, preferably from 1 to 6 hours.

[0125] Thus, in a preferred aspect, the present invention relates to a process for preparing a sulfur copolymer, wherein the copolymerization step is carried out without the use of a solvent and preferably at a temperature in the range of 120-230° C.

[0126] More preferably, the process for preparing the sulfur copolymer comprises the steps of: a) providing an anionic polymerization initiator and elemental sulfur; b) heating the mixture obtained in step a) to a temperature of 120-230°C; c) copolymerizing the cyclic monothiocarbonate compound of formula (I) with sulfur while optionally further adding elemental sulfur to form a reaction mixture comprising a copolymer; and d) Optionally, separating the copolymer from the reaction mixture.

[0127] Step d) is preferably carried out by homogenization and filtration.

[0128] The addition of the cyclic monothiocarbonate compound of formula (I) and optionally further elemental sulfur may be carried out simultaneously or alternately.

[0129] Preferably, the process of step a) is carried out at a temperature of 120-230°C, more preferably at a temperature of 170-230°C, especially at a temperature in the range of 170-190°C, 190-210°C or 210-230°C.

[0130] The copolymerization step is preferably carried out at a temperature in the range of 120-150°C, 150-170°C, 170-190°C, 190-210°C or 210-230°C.

[0131] More preferably, the copolymerization step is carried out at a temperature in the range of 170-190°C, 190-210°C, or 210-230°C.

[0132] The reaction time of the copolymerization step can usually be in the range of 0.5 to 8 hours, preferably 1 to 6 hours.

[0133] More preferably, the present invention relates to a process for preparing a sulfur copolymer, the process comprising the following steps: a) providing an anionic polymerization initiator and elemental sulfur; b) heating the product of step a) to a temperature in the range of 170-230°C; c) copolymerizing the cyclic monothiocarbonate compound of formula (I) and sulfur for 0.5 to 8 hours while adding the cyclic monothiocarbonate compound of formula (I) and optionally further elemental sulfur to the mixture obtained in step a) to form a reaction mixture comprising a copolymer; and d) Optionally, separating the copolymer from the reaction mixture.

[0134] The ratio of monomers used in the present process is generally selected to provide the desired properties of the sulfur copolymer.

[0135] The elemental sulfur and the cyclic monothiocarbonate compound of formula (I) can be used in various molar ratios, for example, the molar ratio of the cyclic monothiocarbonate compound of formula (I) to elemental sulfur is 99:1 to 1:99, preferably 80:20 to 20:80.

[0136] Thus, in a preferred aspect, the present invention relates to a process for preparing a sulfur copolymer, wherein the step of copolymerizing the cyclic monothiocarbonate compound of formula (I) with elemental sulfur is carried out in a molar ratio ranging from 99:1 to 1:99.

[0137] In a further aspect, the present invention relates to a sulfur copolymer obtainable by the process described in any aspect herein.

[0138] The present invention therefore relates to a sulfur copolymer obtainable by a process, which process comprises the formula [ka] [In the formula, R 1 and R 2 are each independently hydrogen, C1-C 18 C1-C substituted with alkyl, halogen or interrupted by O or S 18 Alkyl; C1-C4 alkyl, C1-C4 alkoxy, C1-C4 alkylthio or C6-C substituted with halogen 18 Aryl or C6-C12 is aryl] with elemental sulfur in the presence of a polymerization initiator.

[0139] Since this process typically provides a mixture of one or more sulfur copolymers, the present invention also relates to a composition comprising one or more sulfur copolymers obtainable by the process, which process comprises a sulfur copolymer having the formula [ka] [In the formula, R 1 and R 2 are each independently hydrogen, C1-C 18 C1-C substituted with alkyl, halogen or interrupted by O or S 18 Alkyl; C1-C4 alkyl, C1-C4 alkoxy, C1-C4 alkylthio or C6-C substituted with halogen 18 Aryl or C6-C 12 is aryl] with elemental sulfur in the presence of a polymerization initiator.

[0140] The polysulfide units derived from elemental sulfur are derived from a cyclic monothiocarbonate compound of formula (I): [ka] or [ka] and / or may be incorporated adjacent to the β-carbon atom of an alkylene sulfide unit of formula (VIa) or (VIb).

[0141] Thus, the sulfur copolymer has the formula [ka] Alkylene units and polysulfides (S)x units, where x can be from about 1 to 10, preferably from 1 to 8, and the copolymer includes at least one S-S bond.

[0142] Thus, in one preferred aspect, the present invention relates to a sulfur copolymer, said copolymer having the formula [ka] and polysulfide S x unit, where x is 1 to 10, preferably 1 to 8; and The copolymer contains at least one S—S bond.

[0143] More preferably, the process provides a sulfur copolymer comprising n alkylene units of formula (IV) and (n+1) polysulfide units, the polysulfide units comprising in total from (2n+1) to (2n+9) sulfur atoms, where n is 1 or more, in particular from (2n+1) to (2n+8) sulfur atoms, in particular from (2n+1) to (2n+7) sulfur atoms.

[0144] Thus, in a more preferred aspect, the present invention relates to a sulfur copolymer obtainable by this process, said copolymer having the formula [ka] The sulfur copolymer contains n alkylene units and (n+1) polysulfide units, and the polysulfide units contain a total of (2n+1) to (2n+9) sulfur atoms, n is 1 or more, and R 1 and R 2 are each independently hydrogen, C1-C 18 C1-C substituted with alkyl, halogen or interrupted by O or S 18 Alkyl; C1-C4 alkyl, C1-C4 alkoxy, C1-C4 alkylthio or C6-C substituted with halogen 18Aryl or C6-C 12 It is aryl.

[0145] In particular, the polysulfide units contain a total of (2n+1) to (2n+8) sulfur atoms, in particular (2n+1) to (2n+7) sulfur atoms.

[0146] In a further aspect, the present invention relates to a sulfur copolymer, the copolymer having the formula [ka] and polysulfide units (n+1), the polysulfide units containing a total of (2n+1) to (2n+9) sulfur atoms; In particular, it contains from (2n+1) to (2n+8) sulfur atoms, in particular from (2n+1) to (2n+7) sulfur atoms, n is 1 or more, and R 1 and R 2 are each independently hydrogen, C1-C 18 C1-C substituted with alkyl, halogen or interrupted by O or S 18 Alkyl; C1-C4 alkyl, C1-C4 alkoxy, C1-C4 alkylthio or C6-C substituted with halogen 18 Aryl or C6-C 12 It is aryl.

[0147] In a further aspect, the present invention relates to a composition comprising one or more sulfur copolymers, the copolymers having the formula [ka] and (n+1) polysulfide units, the polysulfide units containing a total of (2n+1) to (2n+9) sulfur atoms; In particular, it contains from (2n+1) to (2n+8) sulfur atoms, in particular from (2n+1) to (2n+7) sulfur atoms, n is 1 or more, and R 1 and R 2are each independently hydrogen, C1-C 18 C1-C substituted with alkyl, halogen or interrupted by O or S 18 Alkyl; C1-C4 alkyl, C1-C4 alkoxy, C1-C4 alkylthio or C6-C substituted with halogen 18 Aryl or C6-C 12 It is aryl.

[0148] The composition may additionally further comprise a reaction product having only one polysulfide unit incorporated between two end groups resulting from the cyclic monothiocarbonate compound of formula (I).

[0149] Thus, preferred are compositions comprising one or more sulfur copolymers, which have the formula [ka] [In the formula, x is 2 to 8 and represents the total number of sulfur atoms present in formulae (IIIa), (IIIb), and (IIIc)] The polysulfide compound may be one or more of the above polysulfide compounds.

[0150] Typically, the sulfur copolymers can have an average molecular weight of up to 20,000 g / mol, preferably up to 10,000, more preferably up to 5,000. As used herein, the term "molecular weight" refers to the number average molecular weight Mn, which is typically determined by gel permeation chromatography (GPC) using polystyrene as a standard.

[0151] The sulfur copolymer or the polymer composition containing one or more sulfur copolymers may be processed into a desired form by conventional methods suitable for the respective application. For example, the sulfur copolymer may be used in optical applications, sealant applications, immobilization of sulfur in polymer matrices, metal working fluids and / or as active materials in Li-S batteries.

[0152] Thus, in a further aspect, the present invention relates to an article formed using the sulfur copolymers described in any of the aspects herein or using a polymer composition comprising one or more sulfur copolymers described in any of the aspects herein.

[0153] The present invention further relates to the use of the sulfur copolymers according to any of the embodiments of the present invention, or polymer compositions comprising one or more of the sulfur copolymers according to any of the embodiments of the present invention, in optical applications, sealant applications, immobilization of sulfur in polymer matrices, as metal working fluids and / or as active materials in Li-S batteries.

[0154] The attractive chemical accessibility and performance properties of cyclic monothiocarbonate compounds are used in conjunction with elemental sulfur to create a novel chemical platform for sulfur-based polymeric materials.

[0155] The present process allows for industrially viable production and / or allows for a readily accessible synthetic route to organosulfur copolymers that is economical and flexible.

[0156] Additionally, the process allows for the preparation of sulfur copolymers using S-containing monomers that have improved storage stability compared to ethylene sulfide or propylene sulfide.

[0157] The process allows for easy access to copolymers having the desired sulfur content, which can be tailored to be suitable for use in a variety of applications, for example, the process can be tailored to obtain sulfur copolymers suitable for forming sealants.

[0158] In particular, the process provides ready access to copolymers with, for example, high sulfur content, suitable for immobilization of sulfur in polymer matrices, use as metalworking fluids and / or active materials in Li-S batteries.

[0159] For example, a sulfur copolymer having a high sulfur content and / or a high viscosity can be suitably used as a metal working oil.

[0160] When sulfur copolymers are used in optical elements, it may be desirable to use a relatively small amount of sulfur in the process to provide optical transparency.Thus, the sulfur copolymers of the present invention exhibit high refractive indexes, for example, about 1.65-2.1 at visible and infrared wavelengths, and therefore may be suitable for forming optical elements such as lenses, prisms and waveguides.

[0161] The definitions and preferences given with respect to the processes described herein above apply to any combination thereof as well as to any combination of the other aspects of the invention.

[0162] The present invention will now be described in more detail with reference to the following examples, which should not be construed as limiting. Unless otherwise specified, "%" is always % by weight (wt%). EXAMPLES

[0163] [ka] S8 (25.6 g, 0.1 mol) and Na2S (0.78 g, 0.01 mol) were added to the flask and heated to 180-190 °C under nitrogen atmosphere, forming a viscous fluid under stirring. Me-CTC of formula (Vb) (23.6 g, 0.2 mol) was added dropwise within 30 min, forming a reddish brown mixture under gas evolution. The mixture was stirred at 200 °C for 2 h, forming a black viscous mixture. After cooling, a portion of the mixture was dissolved in chloroform, the solid residue was removed by filtration, and the solvent was removed under reduced pressure. A dark viscous liquid product was obtained.

[0164] The product was identified by HRMS-HPLC coupling as a composition containing a propylene sulfide-sulfur copolymer of the following formula:

[0165] [Table 1]

[0166] M r = monoisotopic relative molecular weight (dimensionless) The empirical formula was confirmed by accurate mass spectrometry. 2 in one ethylene unit * indicates one H and one Me.

[0167] By HPLC analysis, longer sulfur copolymers could not be obtained because they did not pass through the column intact. Each copolymer identified by HRMS contains two oxygen atoms, and it is hypothesized that the presence of oxygen is an artifact due to the analytical procedure.

[0168] HPLC-MS: Thermo Scientific Q Exactive Plus Orbitrap LC-MS / MS System (Column XSelect CSH C18, 150x3.0mm, 3.5μm; 1.0ml / min, 40℃; eluent THF)

[0169] Elemental analysis (Analyzer Vario Micro Cube / ELEMENTAR) S: 77g / 100g The molar ratio of C:H:S was found to be 3:6:5.1 by elemental analysis.

Claims

1. A method for preparing a sulfur copolymer, wherein the method is based on the formula 【Chemistry 1】 [In the formula, R １ and R ２ are, independently of one another, hydrogen, C １ -C １８ alkyl, C substituted with halogen or interrupted by O or S １ -C １８ alkyl; C6-C18 aryl, or C １ -C ４ alkyl, C １ -C ４ alkoxy, C １ -C ４ alkylthio or C aryl substituted with halogen ６ -C １２ aryl]] A method comprising the step of copolymerizing a cyclic monothiocarbonate compound with elemental sulfur in the presence of a polymerization initiator.

2. R １ and R ２ However, they are independent of each other, hydrogen, C １ ~C ４ C substituted with alkyl or halogen or interrupted with O or S １ ~C １８ Alkyl; C ６ ~C １２ Aryl, or C １ ~C ４ Alkyl, C １ ~C ４ Alkoxy, C １ ~C ４ C substituted with alkylthio or halogen ６ ~C １２ The method according to claim 1, wherein the aryl is used.

3. R １ However, it is hydrogen, and R ２ However, hydrogen, C １ ~C ４ C substituted with alkyl or halogen or interrupted with O or S １ ~C ８ The method according to claim 1 or 2, wherein the alkyl or phenyl is used.

4. R １ is hydrogen, and R ２ However, hydrogen or C １ ~C ４ The method according to any one of claims 1 to 3, wherein the alkyl group is alkyl.

5. The method according to any one of claims 1 to 4, wherein the polymerization initiator is an anionic polymerization initiator selected from the group consisting of amine-containing bases, organophosphine compounds, metal salts of mercapto compounds, metal alkoleates, and basic inorganic salts.

6. The method according to claim 5, wherein the anionic polymerization initiator is selected from basic inorganic salts.

7. The method according to any one of claims 1 to 6, wherein the copolymerization step is carried out at a temperature in the range of 40 to 230°C.

8. The method according to any one of claims 1 to 7, wherein the copolymerization step is carried out without the use of a solvent and preferably at a temperature in the range of 120 to 230°C.

9. The aforementioned method: a) Providing the anionic polymerization initiator and elemental sulfur; b) Heat the mixture obtained in step a) to a temperature of 120-230°C; c) A step of copolymerizing the cyclic monothiocarbonate compound of formula (I) with sulfur, while optionally adding further elemental sulfur, to form a reaction mixture containing a copolymer; and d) If applicable, the step of separating the copolymer from the reaction mixture. The method according to any one of claims 1 to 8, comprising:

10. The method according to any one of claims 1 to 9, wherein the step of copolymerizing a cyclic monothiocarbonate compound of formula (I) with elemental sulfur is carried out in a molar ratio in the range of 99:1 to 1:

99.

11. A sulfur copolymer, of the formula 【Chemistry 2】 It contains n alkylene units and (n+1) polysulfide units, and the polysulfide units contain a total of (2n+1) to (2n+9) sulfur atoms. n is 1 or greater, and R １ and R ２ However, the sulfur copolymers are independently of each other: hydrogen, C1-C18 alkyl, halogen-substituted or interrupted by O or S; C6-C18 aryl, or C1-C4 alkyl, C1-C4 alkoxy, C1-C4 alkylthio, or halogen-substituted C6-C12 aryl.

12. The sulfur copolymer according to claim 11, wherein the polysulfide unit contains a total of (2n+1) to (2n+8) sulfur atoms, preferably (2n+1) to (2n+7) sulfur atoms, and n is 1 or more.

13. A composition comprising one or more sulfur copolymers as defined in claim 11 or 12.

14. The aforementioned composition is, 【Transformation 3】 [In the formulas, x is between 2 and 8, and represents the total number of sulfur atoms present in formulas (IIIa), (IIIb), and (IIIc).] R １ and R ２ These are, independently of each other, hydrogen, C1-C18 alkyl, halogen-substituted or interrupted by O or S C1-C18 alkyl; C6-C18 aryl, or C1-C4 alkyl, C1-C4 alkoxy, C1-C4 alkylthio or halogen-substituted C6-C12 aryl. The composition according to claim 13, comprising one or more polysulfide compounds.

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