Modified diene polymer

Abstract

To provide a diene-based polymer that allows for controlled crosslinking morphology.SOLUTION: A modified diene-based polymer has a structure represented by the formula (1). [In the formula (1), R1 and R2 represent an alkyl group having 1 or more carbon atoms, an aryl group having 6 or more carbon atoms, an aralkyl group having 6 or more carbon atoms, a hydrogen atom, or a halogen atom; and Z is an organic group, or an organic group with some hydrogen atoms being substituted, a hydrogen atom, or a halogen atom].SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a modified diene polymer having a specific functional group introduced into the main chain. [Background technology]

[0002] Diene polymers obtained by polymerizing a monomer composition containing a conjugated diene compound have double bonds in their molecular chains. Therefore, diene polymers are used as raw materials capable of forming crosslinked structures. Such diene polymers undergo addition polymerization of a co-crosslinking agent to the double bonds in the molecular chain to form graft chains, thereby forming crosslinked structures. The crosslinking form of the diene polymer affects the mechanical properties of the resulting crosslinked product (cured product). Therefore, it has been proposed to change the crosslinking form and control the properties of the crosslinked product by adding an additive to the diene polymer and the co-crosslinking agent.

[0003] However, the control of crosslinking morphology by additives cannot be performed efficiently and uniformly on all grafted chains, and additives may cause non-grafted chains that reduce the crosslink density or the generation of by-products due to side reactions, which may result in a decrease in the mechanical properties of the crosslinked product.

[0004] It has been proposed to control the crosslinking form of polyolefin polymers by introducing functional groups into the molecular chains. For example, Patent Document 1 and Non-Patent Documents 1 and 2 describe a method in which a photoactive amide compound is irradiated with light or heated to generate radicals, and a substituent having a dithiocarbonyl group is introduced into an olefin polymer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2019 / 070889 [Non-patent literature]

[0006] [Non-Patent Document 1] Jill B. Williamson and three others, "Regioselective CH Xanthylation as a Platform for Polyolefin Functionalization," Angewandte Chemie International Edition, Germany, John Wiley & Sons (Wiley-VCH), 2018, Vol. 57, pp. 6291-6265 [Non-patent document 2] Jill B. Williamson and five others, "Chemo- and Regioselective Functionalization of Isotactic Polypropylene: A Mechanistic and Structure-Property Study," Journal of the American Chemical Society, (USA), American Chemical Society, 2019, Vol. 141, No. 32, pp. 12815-12823 Summary of the Invention [Problem to be solved by the invention]

[0007] In polyolefin polymers, the introduction of functional groups into the molecular chain makes it possible to control the crosslinking form. However, in diene polymers, when functional groups are introduced into the molecular chain using the method described in Patent Document 1, etc., crosslinking occurs between the diene polymers. This has an adverse effect when the diene polymer into which functional groups have been introduced is crosslinked using a co-crosslinking agent. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a modified diene polymer in which the crosslinking form can be controlled. [Means for solving the problem]

[0008] The modified diene polymer of the present invention, which has been able to solve the above problems, is characterized by having a structure represented by formula (1).

[0009] [ka] [In formula (1), R 1 and R 2 represents an alkyl group having 1 or more carbon atoms, an aryl group having 6 or more carbon atoms, an aralkyl group having 6 or more carbon atoms, a hydrogen atom, or a halogen atom. Z is an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, a heterocyclyl group, an alkoxy group, an aryloxy group, an aralkyloxy group, a heterocyclyloxy group, an alkanoyl group, an aroyl group, a heterocyclylcarbonyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a heterocyclyloxycarbonyl group, an alkanoyloxy group, an aroyloxy group, a heterocyclylcarbonyloxy group, a carbamoyl group, a carboxy group, an alkylthio group, an arylthio group, an amino group, a cyano group, a dialkylphosphonate group, a diarylphosphonate group, a dialkylphosphinate group, a diarylphosphinate group, an organic group in which some of the hydrogen atoms of these organic groups have been substituted, or a hydrogen atom or a halogen atom.

[0010] The modified diene polymer of the present invention has a substituent having a dithioester structure introduced into a part of the molecular chain. Therefore, when this modified diene polymer is crosslinked using a co-crosslinking agent, it is thought that graft chains are easily formed at the site where the substituent having the dithioester structure is introduced. Therefore, it is thought that the use of the modified diene polymer of the present invention can control the crosslinking morphology of the obtained crosslinked product. [Effects of the Invention]

[0011] By using the modified diene polymer of the present invention, the crosslinking form of the resulting crosslinked product can be controlled, and the mechanical properties of the crosslinked product can be controlled. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a 1H-NMR spectrum of modified diene polymer No. 1. [Figure 2] IR spectra of modified diene polymers No. 1 and 2 and unmodified polybutadiene. [Figure 3] IR spectra of modified diene polymers No. 1 and 2 and unmodified polybutadiene. [Figure 4] 1 shows UV-VIS spectra of modified diene polymers No. 1 and 2 and unmodified polybutadiene. DETAILED DESCRIPTION OF THE INVENTION

[0013] [Modified diene polymer] The modified diene polymer of the present invention is characterized by having a structure represented by formula (1): The structure represented by formula (1) may be of one type or of two or more types.

[0014] [ka] [In formula (1), R 1 and R 2 represents an alkyl group having 1 or more carbon atoms, an aryl group having 6 or more carbon atoms, an aralkyl group having 6 or more carbon atoms, a hydrogen atom, or a halogen atom. Z is an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, a heterocyclyl group, an alkoxy group, an aryloxy group, an aralkyloxy group, a heterocyclyloxy group, an alkanoyl group, an aroyl group, a heterocyclylcarbonyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a heterocyclyloxycarbonyl group, an alkanoyloxy group, an aroyloxy group, a heterocyclylcarbonyloxy group, a carbamoyl group, a carboxy group, an alkylthio group, an arylthio group, an amino group, a cyano group, a dialkylphosphonate group, a diarylphosphonate group, a dialkylphosphinate group, a diarylphosphinate group, an organic group in which some of the hydrogen atoms of these organic groups have been substituted, or a hydrogen atom or a halogen atom.

[0015] R 1 and R 2 Examples of the alkyl group having 1 or more carbon atoms and represented by the formula (I) include a linear alkyl group, a branched alkyl group, and a cyclic alkyl group. The number of carbon atoms in the alkyl group is preferably 18 or less, more preferably 12 or less, and even more preferably 6 or less. Examples of the linear alkyl group include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, and an n-pentyl group. Examples of the branched alkyl group include an isopropyl group, an isobutyl group, and a t-butyl group. Examples of the cyclic alkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group.

[0016] R 1 and R 2 The aryl group having 6 or more carbon atoms and represented by the formula (I) and optionally having a substituent includes a monocyclic aryl group and a polycyclic aryl group. The number of carbon atoms in the aryl group is preferably 20 or less, more preferably 14 or less. Examples of the aryl group include a phenyl group and a naphthyl group. Note that in the aryl group, a hydrogen atom may be substituted with an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, or a halogen atom.

[0017] R 1 and R 2The number of carbon atoms in the aralkyl group having 6 or more carbon atoms, which may have a substituent represented by the formula (I), is preferably 20 or less, more preferably 14 or less. The aralkyl group is one in which at least one hydrogen atom of an alkyl group is substituted with an aryl group. The aryl group contained in the aralkyl group includes a monocyclic aryl group and a polycyclic aryl group. The alkylene group contained in the aralkyl group may be either linear or branched. Examples of the aralkyl group include a benzyl group, a phenylethyl group, a phenylpropyl group, a phenylbutyl group, an α-cumyl group, and a 1-phenylethyl group. In addition, the aralkyl group may be one in which a hydrogen atom of the aryl group contained in the aralkyl group is substituted with an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, or a halogen atom.

[0018] R 1 and R 2 Examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0019] In the formula (1), R 1 and R 2 is preferably a hydrogen atom, a halogen atom or an alkyl group having 1 to 18 carbon atoms, and particularly preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an s-butyl group or a t-butyl group.

[0020] Examples of the organic group represented by Z include the following. The alkyl group includes a linear alkyl group, a branched alkyl group, and a cyclic alkyl group. The alkyl group preferably has 18 or less carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a t-butyl group, a dodecyl group, a cyclopentyl group, and a cyclohexyl group. The alkenyl group includes a linear alkenyl group, a branched alkenyl group, and a cyclic alkenyl group. The number of carbon atoms in the alkenyl group is preferably 18 or less. Examples of the alkenyl group include a vinyl group, a propenyl group, a butenyl group, and a pentenyl group. The alkynyl group includes a linear alkynyl group, a branched alkynyl group, and a cyclic alkynyl group. The number of carbon atoms in the alkynyl group is preferably 18 or less. Examples of the alkynyl group include an ethynyl group, a propynyl group, a butynyl group, and a pentynyl group.

[0021] The aryl group includes a monocyclic aryl group and a polycyclic aryl group. The number of carbon atoms in the aryl group is preferably 20 or less. Examples of the aryl group include a phenyl group and a naphthyl group. The aryl group contained in the aralkyl group includes a monocyclic aryl group and a polycyclic aryl group. The number of carbon atoms in the aralkyl group is preferably 20 or less. Examples of the aralkyl group include a benzyl group, a phenylethyl group, a phenylpropyl group, a phenylbutyl group, an α-cumyl group, and a 1-phenylethyl group.

[0022] The heterocyclyl group is a group obtained by removing one hydrogen atom from any ring atom of a heterocyclic compound. The heterocyclic compound is a cyclic compound having carbon atoms and atoms other than carbon atoms as ring atoms, and is preferably a 4- to 7-membered ring. The atoms other than carbon atoms constituting the heterocyclic compound are preferably at least one selected from nitrogen atoms, oxygen atoms, and sulfur atoms. Examples of the heterocyclyl group include pyrrolidyl groups, piperidyl groups, pyrrolyl groups, pyridyl groups, tetrahydrofuryl groups, tetrahydropyranyl groups, furyl groups, tetrahydrothienyl groups, tetrahydrothiopyranyl groups, thienyl groups, imidazolidinyl groups, imidazolyl groups, imidazolyl groups, pyrazolyl groups, oxazolidinyl groups, oxazolyl groups, thiazolidinyl groups, thiazolyl groups, piperazyl groups, morpholyl groups, pyridazinyl groups, pyrimidinyl groups, pyrazinyl groups, quinolyl groups, isoquinolyl groups, and quinazolinyl groups.

[0023] The number of carbon atoms in the alkoxy group is preferably not more than 18. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. The number of carbon atoms in the aryloxy group is preferably not more than 20. Examples of the aryloxy group include a phenoxy group. The number of carbon atoms in the aralkyloxy group is preferably not more than 20. Examples of the aralkyloxy group include an α-cumyloxy group. Examples of the heterocyclyloxy group include a pyrrolyloxy group, a pyridyloxy group, and a pyrimidinyloxy group.

[0024] The number of carbon atoms in the alkanoyl group is preferably not more than 18. Examples of the alkanoyl group include a formyl group, an acetyl group, a propionyl group, and a butyryl group. The number of carbon atoms in the aroyl group is preferably not more than 20. Examples of the aroyl group include a benzoyl group and a naphthoyl group. Examples of the heterocyclylcarbonyl group include a pyrrolylcarbonyl group, a pyridylcarbonyl group, and a pyrimidylcarbonyl group.

[0025] The number of carbon atoms in the alkoxycarbonyl group is preferably not more than 19. Examples of the alkoxycarbonyl group include a methoxycarbonyl group, an ethoxycarbonyl group, and a propoxycarbonyl group. The number of carbon atoms in the aryloxycarbonyl group is preferably not more than 21. Examples of the aryloxycarbonyl group include a phenoxycarbonyl group. Examples of the heterocyclyloxycarbonyl group include a pyrrolyloxycarbonyl group, a pyridyloxycarbonyl group, and a pyrimidinyloxycarbonyl group.

[0026] The number of carbon atoms in the alkanoyloxy group is preferably not more than 18. Examples of the alkanoyloxy group include an acetyloxy group and a propionyloxy group. The number of carbon atoms in the aroyloxy group is preferably not more than 20. Examples of the aroyloxy group include a benzoyloxy group and a 1-naphthoyloxy group. Examples of the heterocyclylcarbonyloxy group include a pyrrolylcarbonyloxy group, a pyridylcarbonyloxy group, and a pyrimidinylcarbonyloxy group.

[0027] The number of carbon atoms in the alkylthio group is preferably not more than 18. Examples of the alkylthio group include a methylthio group, an ethylthio group, a propylthio group, and a dodecylthio group. The number of carbon atoms in the arylthio group is preferably not more than 20. Examples of the arylthio group include a phenylthio group.

[0028] Examples of the substituent of the organic group in which some of the hydrogen atoms of the organic group have been substituted include an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, a heterocyclyl group, an alkoxy group, an aryloxy group, an aralkyloxy group, a heterocyclyloxy group, an alkanoyl group, an aroyl group, a heterocyclylcarbonyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a heterocyclyloxycarbonyl group, an alkanoyloxy group, an aroyloxy group, a heterocyclylcarbonyloxy group, a carbamoyl group, a carboxy group, an alkylthio group, an arylthio group, an amino group, a cyano group, an oxo group, and a halogen atom.

[0029] Examples of the organic group in which some of the hydrogen atoms of the organic group have been substituted include a cyanoalkyl group, a halogenated alkyl group, and an alkylamino group. Specific examples include an oxopyrrolidin-1-yl group, a methylphenylamino group, a methylpyridylamino group, a 3,5-dimethylpyrazolyl group, a 4-chloro-3,5-dimethylpyrazolyl group, a cyanomethyl group, a 2-cyanonobutan-2-yl group, a 1-cyanoethan-1-yl group, a 2-cyanopropan-2-yl group, a 2-phenylpropan-2-yl group, a 1-cyano-1-phenylethan-1-yl group, and a 2-(ethoxycarbonyl)propan-2-yl group.

[0030] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0031] In the formula (1), Z is preferably an alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, or a structure represented by any of the formulae (11) to (16).

[0032] [ka] [In formulas (11) to (16), R 11 ~R 16 represents an alkyl group having 1 to 18 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aralkyl group having 6 to 20 carbon atoms, a hydrogen atom, or a halogen atom.]

[0033] The structure represented by (1) is particularly preferably a structure represented by formula (1-1): When Z in formula (1) has a pyrazole ring, crosslinking controllability is improved when a crosslinked structure is formed using the modified diene polymer.

[0034] [ka] [In formula (1-1), R 1 and R 2 represents an alkyl group having 1 or more carbon atoms, an aryl group having 6 or more carbon atoms, an aralkyl group having 6 or more carbon atoms, a hydrogen atom, or a halogen atom. X 1 , X 2 and X 3 represents an alkyl group having 1 or more carbon atoms, an aryl group having 6 or more carbon atoms, an aralkyl group having 6 or more carbon atoms, a hydrogen atom, or a halogen atom.

[0035] R in the formula (1-1) 1 and R 2 Specific examples of R in formula (1) 1 and R 2 Specific examples of R in the formula (1-1) include: 1 and R 2is preferably a hydrogen atom, a halogen atom or an alkyl group having 1 to 18 carbon atoms, and particularly preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an s-butyl group or a t-butyl group.

[0036] X in the formula (1-1) 1 ~X 3 The alkyl group having 1 or more carbon atoms represented by the formula (I) includes a linear alkyl group, a branched alkyl group, and a cyclic alkyl group. The number of carbon atoms in the alkyl group having 1 or more carbon atoms is preferably 18 or less, more preferably 12 or less, and even more preferably 4 or less. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a t-butyl group, a dodecyl group, a cyclopentyl group, and a cyclohexyl group.

[0037] X in the formula (1-1) 1 ~X 3 The aryl group having 6 or more carbon atoms represented by the formula (I) includes a monocyclic aryl group and a polycyclic aryl group. The number of carbon atoms in the aryl group having 6 or more carbon atoms is preferably 20 or less, and more preferably 14 or less. Examples of the aryl group include a phenyl group and a naphthyl group.

[0038] X in the formula (1-1) 1 ~X 3 The aryl group contained in the aralkyl group having 6 or more carbon atoms and represented by the formula (I) includes a monocyclic aryl group and a polycyclic aryl group. The number of carbon atoms in the aralkyl group having 6 or more carbon atoms is preferably 20 or less, and more preferably 15 or less. Examples of the aralkyl group include a benzyl group, a phenylethyl group, a phenylpropyl group, a phenylbutyl group, an α-cumyl group, and a 1-phenylethyl group.

[0039] X in the formula (1-1) 1 ~X 3 is preferably an alkyl group having 1 to 4 carbon atoms or a hydrogen atom.

[0040] The content of the structure represented by formula (1) in the modified diene polymer may be adjusted appropriately depending on the desired crosslinking mode. When an elastic material is formed from a polymer composition containing the modified diene polymer, the content of the structure represented by formula (1) in the modified diene polymer is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and even more preferably 0.05% by mass or more, and is preferably 100% by mass or less, more preferably 80% by mass or less, and even more preferably 50% by mass or less.

[0041] (Other ingredients) The modified diene polymer preferably has a structure represented by formula (2): The structure represented by formula (2) may be of one type or of two or more types.

[0042] [ka] [In formula (2), R 3 and R 4 represents an alkyl group having 1 or more carbon atoms, an aryl group having 6 or more carbon atoms, an aralkyl group having 6 or more carbon atoms, a hydrogen atom, or a halogen atom.

[0043] R in the formula (2) 3 and R 4 Specific examples of R in formula (1) 1 and R 2 Specific examples of R in the formula (2) include: 3 and R 4 is preferably a hydrogen atom, a halogen atom or an alkyl group having 1 to 18 carbon atoms, and particularly preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an s-butyl group or a t-butyl group.

[0044] The modified diene polymer may have a structure derived from another vinyl monomer in addition to the structure represented by formula (1) and the structure represented by formula (2). Examples of the other vinyl monomer include aromatic vinyl monomers such as styrene, (meth)acrylic monomers such as acrylonitrile, and alkenes such as isobutene.

[0045] The total content of the structure represented by formula (1) and the structure represented by formula (2) in the modified diene polymer is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, even more preferably 0.05% by mass or more, still more preferably 50% by mass or more, and particularly preferably 80% by mass or more. The modified diene polymer may have only the structure represented by formula (1) and the structure represented by formula (2).

[0046] The modified diene polymer preferably has an absorption peak (maximum value) in the ultraviolet-visible light absorption spectrum at a wavelength of 350 nm to 600 nm (more preferably 380 nm to 500 nm). The peak appearing in this wavelength region is believed to be derived from a substituent introduced into the diene polymer. Having an absorption peak in this wavelength region makes it easier to control the reaction during synthesis of the modified diene polymer, and can suppress the formation of a crosslinked structure in the resulting modified diene polymer.

[0047] The modified diene polymer preferably does not have a crosslinked structure between molecular chains. The presence or absence of a crosslinked structure can be evaluated by performing a swelling test using toluene as a solvent and calculating the network chain density from the results using the Flory-Rehner equation. The network chain density of the modified diene polymer is 0.05 mmol / cm. 3 Preferably, it is less than or equal to 0.02 mmol / cm 3 or less, more preferably 0.01 mmol / cm 3 The network chain density is 0.05 mmol / cm 3 If the modified diene polymer has a temperature of 100°C or less, the polymer has processability equivalent to that of an unmodified diene polymer.

[0048] [Method of manufacturing modified diene polymer] The modified diene polymer can be produced by introducing a functional group having a dithioester structure into a diene polymer. The functional group having a dithioester structure can be introduced by reacting the diene polymer with a dithioester compound. The method for reacting the diene polymer with the dithioester compound is not particularly limited, but a method of irradiating a mixture of these with light is preferred.

[0049] A method for producing a modified diene polymer preferably comprises a first step of mixing a diene polymer with a dithioester compound to prepare a mixture, and a second step of irradiating the mixture with light in an inert atmosphere. By using light to react the diene polymer with the dithioester compound, the formation of crosslinks between molecular chains in the resulting modified diene polymer can be suppressed.

[0050] (1st step) In the first step, a diene polymer and a dithioester compound are mixed together, and the dithioester compound is uniformly dispersed in the diene polymer to prepare a mixture thereof.

[0051] Examples of the diene polymer include a polymer of one kind of conjugated diene monomer, a copolymer of two or more kinds of conjugated diene monomers, and a copolymer of a conjugated diene monomer and another vinyl monomer.

[0052] The conjugated diene monomer is preferably a compound represented by formula (3).

[0053] [ka] [In formula (3), R 5 and R 6 represents an alkyl group having 1 or more carbon atoms, an aryl group having 6 or more carbon atoms, an aralkyl group having 6 or more carbon atoms, a hydrogen atom, or a halogen atom.

[0054] R in the formula (3) 5 and R 6 Specific examples of R in formula (1)1 and R 2 Specific examples of R in the formula (3) include: 5 and R 6 is preferably a hydrogen atom, a halogen atom or an alkyl group having 1 to 18 carbon atoms, and particularly preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an s-butyl group or a t-butyl group.

[0055] The conjugated diene monomer is preferably 1,4-butadiene, 1,2-butadiene, isoprene, or chloroprene.

[0056] Examples of the other vinyl monomers include aromatic vinyl monomers such as styrene, (meth)acrylic monomers such as acrylonitrile, and alkenes such as isobutene.

[0057] Examples of the diene polymer include polybutadiene, polyisoprene, polychloroprene, acrylonitrile butadiene copolymer, styrene butadiene copolymer, styrene isoprene copolymer, butadiene isoprene copolymer, and isobutene isoprene copolymer.

[0058] The diene polymer is preferably a high-cis polybutadiene having cis-1,4-bonds in an amount of 40% by mass or more, preferably 80% by mass or more, and more preferably 90% by mass or more. By using a high-cis polybutadiene with a high content of cis-1,4-bonds, a crosslinked product with high resilience can be obtained. The high-cis polybutadiene preferably has a 1,2-vinyl bond content of 2.0% by mass or less, more preferably 1.7% by mass or less, and even more preferably 1.5% by mass or less. The lower the 1,2-vinyl bond content, the higher the resilience of the crosslinked product.

[0059] The high-cis polybutadiene is preferably synthesized using a rare earth element catalyst, and in particular, the use of a neodymium-based catalyst using a neodymium compound, which is a lanthanum series rare earth element compound, is preferred because it can produce polybutadiene rubber having a high content of 1,4-cis bonds and a low content of 1,2-vinyl bonds with excellent polymerization activity.

[0060] The dithioester compound is preferably a compound represented by formula (4) or a compound represented by formula (5).

[0061] [ka] [In formulas (4) and (5), Z represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, a heterocyclyl group, an alkoxy group, an aryloxy group, an aralkyloxy group, a heterocyclyloxy group, an alkanoyl group, an aroyl group, a heterocyclylcarbonyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a heterocyclyloxycarbonyl group, an alkanoyloxy group, an aroyloxy group, a heterocyclylcarbonyloxy group, a carbamoyl group, a carboxy group, an alkylthio group, an arylthio group, an amino group, a cyano group, a dialkylphosphonate group, a diarylphosphonate group, a dialkylphosphinate group, a diarylphosphinate group, or an organic group in which some of the hydrogen atoms of these organic groups have been substituted, or a hydrogen atom or a halogen atom. R 7 represents a monovalent hydrocarbon group which may have a substituent.]

[0062] Specific examples of Z in the formulas (4) and (5) include those exemplified as specific examples of Z in the formula (1). In the formulas (4) and (5), Z is preferably an alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, or a structure represented by any of the formulas (11) to (16).

[0063] [ka] [In formulas (11) to (16), R 11 ~R 16 represents an alkyl group having 1 to 18 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aralkyl group having 6 to 20 carbon atoms, a hydrogen atom, or a halogen atom.]

[0064] R in the formula (4) 7 As the group, an alkyl group, an aralkyl group, an aryl group, an alkenyl group, an alkynyl group, a carbonyl group, a carboxyl group, or a group in which some of the hydrogen atoms of these hydrocarbon groups have been substituted, or a halogen atom is preferred.

[0065] R in the formula (4) 7 The structure represented by formula (6) is preferred as R 7 If the dithioester compound has a structure represented by formula (6), the R radical (R·) generated from the dithioester compound efficiently captures the polymer radical, thereby further suppressing cross-linking between polymer chains.

[0066] [ka] [In formula (6), R 8 , R 9 and R 10 each independently represents an alkyl group having 1 or more carbon atoms, an alkenyl group having 2 or more carbon atoms, an alkynyl group having 2 or more carbon atoms, an aryl group having 6 or more carbon atoms which may have a substituent, an aralkyl group having 6 or more carbon atoms which may have a substituent, a hydrogen atom, or a halogen atom.

[0067] The alkyl group includes a linear alkyl group, a branched alkyl group, and a cyclic alkyl group. The alkyl group preferably has 18 or less carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a t-butyl group, a dodecyl group, a cyclopentyl group, and a cyclohexyl group. The alkenyl group includes a linear alkenyl group, a branched alkenyl group, and a cyclic alkenyl group. The number of carbon atoms in the alkenyl group is preferably 18 or less. Examples of the alkenyl group include a vinyl group, a propenyl group, a butenyl group, and a pentenyl group. The alkynyl group includes a linear alkynyl group, a branched alkynyl group, and a cyclic alkynyl group. The number of carbon atoms in the alkynyl group is preferably 18 or less. Examples of the alkynyl group include an ethynyl group, a propynyl group, a butynyl group, and a pentynyl group.

[0068] The aryl group contained in the aralkyl group includes a monocyclic aryl group and a polycyclic aryl group. The number of carbon atoms in the aralkyl group is preferably 20 or less. Examples of the aralkyl group include a benzyl group, a phenylethyl group, a phenylpropyl group, a phenylbutyl group, an α-cumyl group, and a 1-phenylethyl group.

[0069] The aryl group includes a monocyclic aryl group and a polycyclic aryl group. The number of carbon atoms in the aryl group is preferably 20 or less. Examples of the aryl group include a phenyl group and a naphthyl group. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0070] R 7 Examples of the substituent that may be contained in the group include an amino group, a cyano group, an oxo group, and a halogen atom.

[0071] R 7 As the group, an alkyl group having 1 to 18 carbon atoms and an aralkyl group having 1 to 20 carbon atoms are preferred, and a t-butyl group, an α-cumyl group, a t-octyl group, or a benzyl group is more preferred.

[0072] The compounds represented by the formulas (4) and (5) are particularly preferably compounds represented by the formulas (4-1) and (5-1). By having a pyrazole ring at the Z moiety in formula (1), a modified diene polymer can be efficiently synthesized.

[0073] [ka] [In formulas (4-1) and (5-1), X 1 , X 2 and X 3 represents an alkyl group having 1 or more carbon atoms, an aryl group having 6 or more carbon atoms, an aralkyl group having 6 or more carbon atoms, a hydrogen atom, or a halogen atom. R 7 represents a monovalent hydrocarbon group which may have a substituent.]

[0074] X in the formulas (4-1) and (5-1) 1 ~X 3 Specific examples of X in formula (1-1) are 1 ~X 3 Specific examples of X in the formulas (4-1) and (5-1) include: 1 ~X 3 is preferably an alkyl group having 1 to 4 carbon atoms or a hydrogen atom.

[0075] R in the formula (4-1) 7 Specific examples of R in formula (4) 7 Specific examples of R in the formula (4-1) include: 7 is preferably an alkyl group having 1 to 18 carbon atoms or an aralkyl group having 1 to 20 carbon atoms, and more preferably a t-butyl group, an α-cumyl group, a t-octyl group or a benzyl group.

[0076] The amount of the dithioester compound may be adjusted appropriately depending on the desired crosslinking mode. When an elastic material is formed from a polymer composition containing the modified diene polymer, the amount of the dithioester compound is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more, relative to 100 parts by mass of the diene polymer, and is preferably 600 parts by mass or less, more preferably 480 parts by mass or less, and even more preferably 300 parts by mass or less.

[0077] The method for mixing the diene polymer and the dithioester compound is not particularly limited, and may be carried out using a known mixer such as a mixer roll, a Banbury mixer, or a kneader.

[0078] (2nd process) In the second step, the mixture is irradiated with light in an inert atmosphere to react the diene polymer with the dithioester compound, thereby introducing a functional group having a dithioester structure into the molecular chain of the diene polymer.

[0079] The inert atmosphere may be a nitrogen atmosphere or a rare gas atmosphere such as argon.

[0080] The type and duration of irradiation of the light beam to be applied to the mixture are not particularly limited as long as they can react the diene polymer with the dithioester compound. For example, the light beam may have a wavelength of 250 nm to 600 nm, and the irradiation duration may be 1 minute to 120 hours.

[0081] Examples of the manner in which the mixture is irradiated with light include a manner in which the mixture is formed into a sheet and the sheet is irradiated with light; and a manner in which the mixture is irradiated with light while being kneaded.

[0082] By irradiating the diene polymer with light for a predetermined period of time, a modified diene polymer is obtained in which a functional group having a dithioester structure is introduced into the diene polymer. The modified diene polymer is preferably washed with an organic solvent to remove unreacted dithioester compound. [Example]

[0083] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the following examples, and all modifications and embodiments that do not deviate from the spirit of the present invention are included within the scope of the present invention.

[0084] [Evaluation method] 1. 1 H NMR (nuclear magnetic resonance) measurement Using a nuclear magnetic resonance (NMR) measuring device (frequency 400 MHz), 1 HNMR was measured using CDCl3 as the solvent.

[0085] 2. Infrared spectroscopy (IR) IR measurements were carried out using a Fourier transform infrared spectrophotometer (FT-IR) using the attenuated total reflectance (ATR) method.

[0086] 3. Ultraviolet-visible spectroscopy (UV-VIS) UV-VIS diffuse transmittance measurements were performed using an ultraviolet-visible spectrophotometer (UV-VIS) with an integrating sphere.

[0087] 4. Chloroform dissolution test Approximately 100 mg of sample and approximately 5 ml of chloroform were added to a vial and left to stand for one day, after which the dissolution of the sample was visually evaluated.

[0088] 5. Network Chain Density Measurement Approximately 100 mg of sample and approximately 5 ml of toluene were added to a vial and left to stand at 40°C for 2 days. If the sample swelled without dissolving, the sample was removed from the vial and its mass was measured. The network chain density was calculated from the sample mass before and after swelling using the Flory-Rehner equation. If the sample was completely dissolved, the network chain density was 0.01 mmol / cm. 3 was considered to be less than

[0089]

number

[0090]

number

[0091] [Preparation of dithioester compounds] (Dithioester Compound No. 1) 1.86 g (20.0 mmol) of 3,5-dimethylpyrazole was weighed into a 100 mL single-neck flask equipped with a stirrer, 30.0 mL of tetrahydrofuran was added, and 1.16 g (20.6 mmol) of powdered potassium hydroxide was further added and stirred to obtain a pale yellow solution.

[0092] Next, 1.98 g (26.0 mmol) of carbon disulfide was added dropwise to the solution while stirring. One hour after the completion of the addition, the precipitate was collected by filtration using a Kiriyama funnel. The residue was washed with diethyl ether and then dried under reduced pressure at 50°C to obtain potassium 3,5-dimethyl-1H-pyrazole-1-dithiocarboxylate represented by formula (7).

[0093] [ka]

[0094] Under a nitrogen atmosphere, 860 mg (2.00 mmol) of [bis(trifluoroacetoxy)iodo]benzene was weighed into a 100 mL single-neck flask equipped with a stirrer. Subsequently, 4.0 mL of α-cumyl alcohol was added to the flask and stirred to obtain a pale yellow solution. Next, 438 mg (2.00 mmol) of potassium 3,5-dimethyl-1H-pyrazole-1-dithiocarboxylate was added to the pale yellow solution, and the mixture was stirred at room temperature for 16.5 hours. After a predetermined time had elapsed, the reaction mixture was concentrated under reduced pressure. The resulting concentrated solution was purified by silica gel column chromatography to obtain 24.5 mg of dithioester compound No. 1 represented by formula (8).

[0095] [ka]

[0096] (Dithioester Compound No. 2) As dithioester compound No. 2, a compound represented by formula (9) (manufactured by Sigma-Aldrich) was used.

[0097] [ka]

[0098] [Preparation of modified diene polymers] (Modified diene polymer No. 1) Using a twin-screw roll, 40.36 g of polybutadiene rubber (JSR Corporation, BR730) and 1.23 g of the dithioester compound No. 1 obtained above were mixed, and the mixture was discharged into a sheet having a thickness of 2 mm or less when discharged from the roll. The discharged sheet-like mixture was cut into sheet pieces approximately 75 mm long and 15 mm wide.

[0099] Next, two supports were installed in an argon-purged glove box, and a horizontal bar was hung between them so that it was horizontal to the ground. A sheet piece was hung from this horizontal bar using a string. Two light sources (Kessil, "A 160 WE Tuna Blue," light wavelength 380 nm to 500 nm) were installed on either side of the sheet piece so that light could be irradiated on both sides of the sheet piece. The sheet piece and the light sources were separated by approximately 15 cm to 20 cm. The light sources were used to irradiate the sheet piece with light for 480 minutes, causing a reaction between the polybutadiene rubber and dithioester compound No. 1. After the reaction, the sheet piece was washed with an organic solvent (a mixed solvent of acetone and tetrahydrofuran in a ratio of 1:2) to remove unreacted materials, producing modified diene-based polymer No. 1.

[0100] (Modified diene polymer No. 2) Using a biaxial roll, 40.36 g of polybutadiene rubber (JSR Corporation, BR730) and 1.72 g of the dithioester compound No. 2 were mixed, and the mixture was discharged into a sheet having a thickness of 2 mm or less when discharged from the roll. The discharged sheet-like mixture was cut into sheet pieces approximately 75 mm long and 15 mm wide.

[0101] Next, two supports were installed in an argon-purged glove box, and a horizontal bar was hung between them so that it was horizontal to the ground. A sheet piece was hung from this horizontal bar using a string. Two light sources (Kessil, "A 160 WE Tuna Blue," light wavelength 380 nm to 500 nm) were installed on either side of the sheet piece so that light could be irradiated on both sides of the sheet piece. The sheet piece and the light sources were separated by approximately 15 cm to 20 cm. The light sources irradiated the sheet piece with light for 480 minutes, causing a reaction between the polybutadiene rubber and dithioester compound No. 2. After the reaction, the sheet piece was washed with an organic solvent (a mixed solvent of acetone and tetrahydrofuran in a ratio of 1:2) to remove unreacted materials, producing modified diene-based polymer No. 2.

[0102] [evaluation] The modified diene polymers No. 1 and 2 obtained above and the unmodified polybutadiene rubber were 1 HNMR measurement, IR measurement, UV-VIS measurement, chloroform dissolution test, and network chain density measurement were carried out. Table 1 shows the results of the chloroform dissolution test and network chain density measurement. Figure 1 shows the results of the modified diene polymer. 1 The results of HNMR measurement are shown in Figures 2 and 3. The results of IR measurement are shown in Figure 4. The results of UV-VIS measurement are shown in Figure 4.

[0103] [Table 1]

[0104] 1The results of HNMR measurement, IR measurement, and UV-VIS measurement confirmed that modified diene-based polymer No. 1 has a structure represented by formula (1-1), and modified diene-based polymer No. 2 has a structure represented by formula (1).

[0105] Modified diene polymer No. 1 and unmodified polybutadiene rubber dissolved in chloroform and toluene. This indicates that the molecular chains were not crosslinked. In contrast, modified diene polymer No. 2 did not dissolve in chloroform, and the sample swelled. This indicates that when the functional group having a dithioester structure was introduced into modified diene polymer No. 2, some crosslinking occurred between the molecular chains of the diene polymer. [Industrial Applicability]

[0106] It is believed that the modified diene polymer of the present invention is likely to form graft chains at the sites where the substituent having a dithioester structure has been introduced, and therefore the modified diene polymer of the present invention is useful as a raw material capable of forming a crosslinked structure.

Claims

1. A modified diene polymer characterized by having a structure represented by formula (1): 【Chemistry 1】 [In formula (1), R 1 and R 2 represents an alkyl group having 1 or more carbon atoms, an aryl group having 6 or more carbon atoms, an aralkyl group having 6 or more carbon atoms, a hydrogen atom, or a halogen atom. Z is an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, an aryloxy group, an aralkyloxy group, a heterocyclyloxy group, an alkanoyl group, an aroyl group, a heterocyclylcarbonyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a heterocyclyloxycarbonyl group, an alkanoyloxy group, an aroyloxy group, a heterocyclylcarbonyloxy group, a carbamoyl group, a carboxy group, an alkylthio group, an arylthio group, a cyano group, a dialkylphosphonate group, a diarylphosphonate group, a dialkylphosphinate group, a diarylphosphinate group, a hydrogen atom, a halogen atom, or a structure represented by formula (11), (12), (13), (15), or (16). 【Chemistry 2】 [In formulas (11), (12), (13), (15) and (16), R 11 ~R 16 represents an alkyl group having 1 to 18 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aralkyl group having 6 to 20 carbon atoms, a hydrogen atom, or a halogen atom.

2. The modified diene polymer according to claim 1, wherein in formula (1), Z is an alkyl group having 1 to 18 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, or a structure represented by formula (11), (12), (13), (15), or (16). 【Transformation 3】 [In formulas (11), (12), (13), (15) and (16), R 11 ~R 16 represents an alkyl group having 1 to 18 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aralkyl group having 6 to 20 carbon atoms, a hydrogen atom, or a halogen atom.

3. The modified diene polymer according to claim 1 or 2, having a structure represented by formula (1-1): 【Chemistry 4】 [In formula (1-1), R 1 and R 2 represents an alkyl group having 1 or more carbon atoms, an aryl group having 6 or more carbon atoms, an aralkyl group having 6 or more carbon atoms, a hydrogen atom, or a halogen atom. X 1 , X 2 and X 3 represents an alkyl group having 1 to 18 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aralkyl group having 6 to 20 carbon atoms, a hydrogen atom, or a halogen atom.

4. The modified diene polymer according to any one of claims 1 to 3, which has an absorption peak in the wavelength range of 350 nm to 600 nm in an ultraviolet-visible light absorption spectrum.

5. The network chain density calculated by the Flory-Rehner equation is 0.05 mmol / cm 3 The modified diene polymer according to any one of claims 1 to 4, wherein:

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