Complex polymer, rubber composition, method for producing rubber composition, and rubber product

Abstract

The problem addressed by the present invention is to provide a polymer that performs as well as a new product. The solution to said problem is a complex polymer containing a polymer main chain containing conjugated diene units and / or olefin units, and a functional group bonded to the polymer main chain, the functional group containing a nitrogen atom and / or a phosphorous atom and being complexed with a metal ion of an element in group 7–10 of the Periodic Table, said complex polymer characterized in that the bond dissociation energy between the metal ion and the functional group is 200 kJ / mol or more.

Description

[Technical Field]

[0001] The present invention relates to a complexed polymer, a rubber composition, a method for producing a rubber composition, and a rubber product. [Background technology]

[0002] Conventionally, most vulcanized rubber products such as used tires have been disposed of without being reused. However, from the viewpoints of environmental issues and resource conservation, there is an urgent need to recycle waste vulcanized rubber such as tires. As a method for regenerating vulcanized rubber, for example, a method is known in which vulcanized rubber is regenerated by applying heat and shear force to the vulcanized rubber using a twin-screw extruder. Furthermore, Patent Document 1 below proposes a technique for devulcanizing vulcanized rubber to regenerate it as unvulcanized rubber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-23225 Summary of the Invention [Problem to be solved by the invention]

[0004] However, cross-linked polymer products such as vulcanized rubber are inevitably deteriorated because they are recycled through treatment under harsh conditions, and there is a problem that, for example, rubber products made from recycled rubber have inferior physical properties such as breaking strength compared to rubber products that do not use recycled rubber. As such, there are still areas that need improvement when it comes to recycling cross-linked polymer products such as vulcanized rubber, and further investigation is currently required.

[0005] Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional technology and to provide a polymer (rubber, etc.) that is recyclable and has performance equivalent to that of a new product. Another object of the present invention is to provide a rubber composition containing such a polymer, a method for producing the rubber composition, and a rubber product. [Means for solving the problem]

[0006] As a result of extensive research to solve the above problems, the present inventors have found that a specific complexing polymer is recyclable and has performance equivalent to that of a new polymer, and have thus completed the present invention. That is, the gist of the present invention that solves the above problems is as follows.

[0007] The complexed polymer of the present invention comprises a polymer backbone comprising conjugated diene units and / or olefin units, and functional groups attached to the polymer backbone, The functional group contains a nitrogen atom and / or a phosphorus atom, and is complexed with a metal ion of an element in Groups 7 to 10 of the periodic table, The bond dissociation energy between the metal ion and the functional group is 200 kJ / mol or more.

[0008] Further, a rubber composition according to one embodiment of the present invention is a rubber composition containing the complexed polymer, The rubber composition is characterized in that the amount of sulfur in the rubber composition is 0.3 parts by mass or less per 100 parts by mass of the rubber component.

[0009] Further, a rubber composition according to another embodiment of the present invention is a rubber composition containing the complex polymer, The rubber composition is characterized in that the content of peroxide in the rubber composition is 0.3 parts by mass or less per 100 parts by mass of the rubber component.

[0010] Further, a method for producing a rubber composition according to one embodiment of the present invention is a method for producing a rubber composition containing the above-mentioned complex polymer, In a first stage of kneading, a polymer main chain and a compound containing a functional group are kneaded to form a functionalized polymer in which the functional group is bonded to the polymer main chain; In the second or subsequent stage of kneading, a metal salt is added and kneaded to complex the functionalized polymer, thereby forming a complexed polymer.

[0011] Further, a method for producing a rubber composition according to another embodiment of the present invention is a method for producing a rubber composition containing the above-mentioned complex polymer, The complexing polymer is formed in advance, and the preformed complexing polymer is blended during kneading.

[0012] The rubber product of the present invention is characterized by containing the above rubber composition. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a polymer that is recyclable and has performance equivalent to that of a new product. Furthermore, the present invention can provide a rubber composition containing such a polymer, a method for producing the rubber composition, and a rubber product. DETAILED DESCRIPTION OF THE INVENTION

[0014] The complexed polymer, rubber composition, method for producing the rubber composition, and rubber product of the present invention will be described in detail below with reference to examples based on embodiments thereof.

[0015] <Complexing polymer> The complexed polymer of the present invention comprises a polymer main chain containing a conjugated diene unit and / or an olefin unit, and a functional group bonded to the polymer main chain, wherein the functional group contains a nitrogen atom and / or a phosphorus atom and is complexed with a metal ion of an element in Groups 7 to 10 of the periodic table, and is characterized in that the bond dissociation energy between the metal ion and the functional group is 200 kJ / mol or more.

[0016] The complex polymer of the present invention comprises a polymer main chain and a functional group, and the functional group is complexed with a metal ion of an element of Groups 7 to 10 of the periodic table. Furthermore, since the bond dissociation energy between the metal ion and the functional group is 200 kJ / mol or more, the polymer main chain is crosslinked with sufficient strength, and the complex polymer has high durability. Furthermore, since the bond between the metal ion and the functional group is not a sulfur bond like that of general vulcanized rubber, the bond can be easily broken, for example, by heating to cause it to flow and be remolded. Because the bond can be easily broken, there is no need to expose the complexed polymer to harsh conditions to break the bond. Furthermore, the functionalized polymer containing a polymer main chain and functional groups produced by breaking the bond between the metal ion and the functional group does not need to be exposed to harsh conditions to break the bond, so the performance of the polymer main chain is maintained. Furthermore, even if the functionalized polymer is complexed with a metal ion to regenerate the complexed polymer, the performance can be maintained at the same level as when it was new. Therefore, the complex polymer of the present invention is recyclable and has the same performance as a new product even after recycling. Furthermore, the present invention can provide a novel polymer having a crosslinking form that replaces sulfur crosslinking.

[0017] (polymer main chain) The complexed polymer of the present invention comprises a polymer main chain containing conjugated diene units and / or olefin units. That is, the polymer main chain contains either conjugated diene units or olefin units, or both conjugated diene units and olefin units. Here, the number of polymer main chains is one or more. When the polymer main chain is one, the complexed polymer forms a crosslinked structure intramolecularly via metal ions. When the polymer main chain is two or more, crosslinked structures can be formed intramolecularly as well as between molecules (between polymer main chains) via metal ions. The complexed polymer has multiple functional groups to form a crosslinked structure, and the multiple functional groups may be bonded to one polymer main chain or may be bonded separately to two or more polymer main chains. The multiple functional groups may be the same or different.

[0018] The conjugated diene unit is a monomer unit derived from a conjugated diene compound. The conjugated diene compound as a monomer preferably has 4 to 8 carbon atoms. Specific examples of such conjugated diene compounds include 1,3-butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-1,3-butadiene. From the viewpoint of good elastomer properties, the conjugated diene compound as a monomer preferably contains 1,3-butadiene and / or isoprene. The proportion of the conjugated diene units in the polymer main chain is not particularly limited and may be 0 mol%, but is preferably 0.1 mol% or more, more preferably 1 mol% or more, and may be 100 mol%. When the proportion is 1 mol% or more, a complexed polymer having excellent elastomeric properties can be obtained.

[0019] The olefin unit is a monomer unit derived from an olefin compound. The olefin compound as a monomer preferably has 2 to 10 carbon atoms. Specific examples of such an olefin compound include α-olefins such as ethylene, propylene, 1-pentene, 1-hexene, 1-heptene, and 1-octene, and heteroatom-substituted alkene compounds such as vinyl pivalate, 1-phenylthioethene, and N-vinylpyrrolidone. The proportion of the olefin units in the polymer main chain is not particularly limited and may be 0 mol %, but is preferably 1 mol % or more, and may also be 100 mol %.

[0020] The polymer main chain may contain units derived from other monomers copolymerizable with the conjugated diene compound and / or the olefin compound. Examples of such units derived from other monomers include aromatic vinyl units. The proportion of the units derived from other monomers in the polymer main chain is not particularly limited and may be 0 mol %, but in one embodiment, it is preferably 1 mol % or more and 50 mol % or less. The aromatic vinyl unit is a monomer unit derived from an aromatic vinyl compound. The aromatic vinyl compound refers to an aromatic compound substituted with at least a vinyl group. The aromatic vinyl compound as a monomer preferably has 8 to 10 carbon atoms. Specific examples of such aromatic vinyl compounds include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-dimethylstyrene, 2-ethylstyrene, 3-ethylstyrene, and 4-ethylstyrene.

[0021] (functional group) The complexed polymer of the present invention contains a functional group bonded to the polymer main chain. The functional group contains a nitrogen atom and / or a phosphorus atom and is complexed with a metal ion of an element of Groups 7 to 10 of the periodic table. When the functional group contains a nitrogen atom and / or a phosphorus atom and is complexed with a metal ion of an element of Groups 7 to 10 of the periodic table, the bond between the functional group and the metal ion becomes strong, allowing for the formation of crosslinks with a strength equivalent to that of sulfur crosslinks. Preferred examples of the nitrogen-containing functional group include groups containing a nitrogen-containing heterocycle such as a 4,5-dihydropyridazine ring, a pyridine ring, a pyrimidine ring, a triazine ring, or a tetrazine ring. Examples of the phosphorus-containing functional group include groups in which the nitrogen in the above-mentioned nitrogen-containing heterocycle is replaced with phosphorus. Here, the functional group preferably does not contain a sulfur atom. When the functional group does not contain a sulfur atom, cross-linking between polymer main chains due to the sulfur atom can be suppressed, and recyclability is improved.

[0022] In the complex polymer of the present invention, the bond dissociation energy between the metal ion and the functional group is 200 kJ / mol or more, preferably 250 kJ / mol or more, and preferably 500 kJ / mol or less. A bond dissociation energy of 200 kJ / mol or more allows for the formation of crosslinks with a strength equivalent to that of sulfur crosslinks, ensuring sufficient durability of the complex polymer. Furthermore, a bond dissociation energy of 250 kJ / mol or more further improves the durability of the complex polymer. Furthermore, a bond dissociation energy of 500 kJ / mol or less allows for easier dissociation of the bond between the metal ion and the functional group, making it easier to recycle the complex polymer.

[0023] In the present invention, the bond dissociation energy between a metal ion and a functional group is a value calculated at the MO6 / 6-31G(d,p) / / B3PW91-D3 / 6-31G(d,p) level or the MO6 / 6-31G(d,p) level in a vacuum. It is assumed that the metal ion and the functional group form ionic aggregates. Gaussian09 or GRRM14 can be used to calculate the bond dissociation energy.

[0024] In the complex polymer of the present invention, the metal ion and the functional group are preferably bonded by a coordinate bond. A coordinate bond can impart sufficient reversibility to the bond between the metal ion and the functional group. Furthermore, a coordinate bond makes it easier for the metal ion and the functional group to form a bond of sufficient strength, and also makes it easier to fluidize the complex polymer by heating, making it easier to reshape, and further improving the recyclability of the complex polymer.

[0025] In the complex polymer of the present invention, the functional group is preferably derived from a compound containing a triazine ring or a tetrazine ring. Compounds containing a triazine ring or a tetrazine ring have high reactivity with the polymer main chain and easily form a functionalized polymer by reacting with the polymer main chain. Furthermore, nitrogen-containing functional groups derived from compounds containing a triazine ring or a tetrazine ring are easily complexed with metal ions of elements in Groups 7 to 10 of the periodic table, and can form crosslinks with strength equivalent to sulfur crosslinks.

[0026] Here, the triazine ring or tetrazine ring of the compound containing a triazine ring or tetrazine ring preferably has a pyridyl group or a pyrimidinyl group bonded thereto, and more preferably has two pyridyl groups or two pyrimidinyl groups bonded thereto. When a pyridyl group or a pyrimidinyl group is bonded to the triazine ring or tetrazine ring, the functional group and the metal ion of an element in Groups 7 to 10 of the periodic table are more likely to form a complex, the bond dissociation energy is more likely to be increased, and a crosslinked structure with even greater strength can be formed. Furthermore, when two pyridyl groups or two pyrimidinyl groups are bonded to the triazine ring or tetrazine ring, the functional group and the metal ion of an element in Groups 7 to 10 of the periodic table are more likely to form a complex, the bond dissociation energy is more likely to be increased, and a crosslinked structure with even greater strength can be formed. The pyridyl group may be a 2-pyridyl group, a 3-pyridyl group, or a 4-pyridyl group, with a 2-pyridyl group being preferred.The pyrimidinyl group may be a 2-pyrimidinyl group, a 4-pyrimidinyl group, or a 5-pyrimidinyl group.

[0027] The functional group is represented by the following general formula (1): [ka] [where, X 1 and X 2 are each independently a pyridyl group or a pyrimidinyl group, and Y 1 and Y 2 are each independently a single bond or a divalent hydrocarbon group. The compound represented by general formula (1) is preferably derived from a compound represented by the formula:

[0023] . The compound represented by general formula (1) readily undergoes a Diels-Alder reaction with a polymer main chain containing a conjugated diene unit and / or an olefin unit, and readily forms a functionalized polymer. Furthermore, when the functional group is derived from a compound represented by general formula (1), the functional group is particularly likely to complex with a metal ion of an element in Groups 7 to 10 of the periodic table, and the bond dissociation energy is particularly likely to be high, resulting in the formation of a crosslinked structure with even greater strength.

[0028] In the above general formula (1), X 1 and X 2are each independently a pyridyl group or a pyrimidinyl group. From the viewpoint of ease of synthesis, X 1 and X 2 is preferably a pyridyl group. The pyridyl group may be a 2-pyridyl group, a 3-pyridyl group, or a 4-pyridyl group, with a 2-pyridyl group being preferred. The pyrimidinyl group may be a 2-pyrimidinyl group, a 4-pyrimidinyl group, or a 5-pyrimidinyl group.

[0029] In the above general formula (1), Y 1 and Y 2 are each independently a single bond or a divalent hydrocarbon group. Here, examples of the divalent hydrocarbon group include an alkylene group, an alkenylene group, and an arylene group. More specifically, examples of the alkylene group include a methylene group, an ethylene group, a trimethylene group, and a tetramethylene group. Examples of the alkenylene group include a vinylene group, a propenylene group, and a butenylene group. Examples of the arylene group include a phenylene group, a tolylene group, and a naphthylene group. From the viewpoint of ease of synthesis, Y 1 and Y 2 is preferably a single bond (i.e., X is not attached to the tetrazine ring). 1 and X 2 is preferably directly bonded).

[0030] Here, X in the general formula (1) 1 and X 2 is a pyridyl group, and Y 1 and Y 2 is preferably a single bond. In this case, the compound of formula (1) is easily available, and is particularly likely to form a complex with a metal ion of an element in Groups 7 to 10 of the periodic table, so that the bond dissociation energy is particularly likely to be high, and a crosslinked structure with even higher strength can be formed.

[0031] The compounds represented by the general formula (1) include 3,6-di(2-pyridyl)-1,2,4,5-tetrazine, 3,6-di(3-pyridyl)-1,2,4,5-tetrazine, 3,6-di(4-pyridyl)-1,2,4,5-tetrazine, 3,6-di(2-pyridylmethyl)-1,2,4,5-tetrazine, 3,6-di(2-pyridylethyl)-1,2,4,5-tetrazine, 3-(2-pyridyl)-1,2,4,5-tetrazine, lysylmethyl)-6-(2-pyridylethyl)-1,2,4,5-tetrazine, 3,6-di(2-pyrimidinyl)-1,2,4,5-tetrazine, 3,6-di(4-pyrimidinyl)-1,2,4,5-tetrazine, 3,6-di(5-pyrimidinyl)-1,2,4,5-tetrazine, and the like. Among these, 3,6-di(2-pyridyl)-1,2,4,5-tetrazine is preferred.

[0032] In the complex polymer of the present invention, the functional group is preferably bonded in an amount of 0.1 to 10 mol % relative to the monomer units in the polymer main chain, more preferably 0.3 to 8 mol %, even more preferably 0.4 to 5 mol %, and particularly preferably 0.5 to 3 mol %. When the functional group is bonded in an amount of 0.1 mol % or more relative to the monomer units in the polymer main chain, crosslinks with a strength equivalent to that of sulfur crosslinking can be formed, resulting in a complex polymer with sufficient durability. Furthermore, when the functional group is bonded in an amount of 10 mol % or less relative to the monomer units in the polymer main chain, a complex polymer with sufficient elastomeric properties is likely to be obtained.

[0033] (metal ions) In the complex polymer of the present invention, the metal ion complexed with the functional group is a metal ion of an element in Groups 7 to 10 of the periodic table, and preferably a metal ion of an element in Group 8 of the periodic table. Specifically, examples of elements in Group 7 of the periodic table include manganese and rhenium. Examples of elements in Group 8 of the periodic table include iron, ruthenium, and osmium. Furthermore, examples of elements in Group 9 of the periodic table include cobalt, rhodium, and iridium. Examples of elements in Group 10 of the periodic table include nickel, palladium, and platinum. Metal ions of elements in Groups 7 to 10 of the periodic table tend to bond strongly with functional groups. Furthermore, when the metal ions are metal ions of elements in Group 8 of the periodic table, they tend to bond even stronger with functional groups, and can form crosslinks with a strength equivalent to that of sulfur crosslinks. Regarding the metal ions of elements in Groups 7 to 10 of the periodic table, the valence of the ions is not particularly limited, and each element can have any valence that it can have.

[0034] As the metal ion, an iron ion is particularly preferable. The iron ion is likely to form a particularly strong bond with a functional group containing a nitrogen atom and / or a phosphorus atom, and can form a stronger crosslinked structure. The valence of the iron ion is divalent (Fe 2+ ) or trivalent (Fe 3+ ) is preferred.

[0035] In the complexed polymer of the present invention, the metal ions are preferably complexed by adding a metal salt to the polymer main chain to which the functional groups are bonded. In this case, the complexed polymer can be easily obtained, and crosslinks of the same strength as sulfur crosslinks can be formed. The form of the metal salt to be added is not particularly limited, and may be, for example, a hydrate. The amount of metal salt added is preferably in the range of 1 to 30 parts by mass, more preferably 1 to 15 parts by mass, even more preferably 1 to 10 parts by mass, and particularly preferably 1 to 5 parts by mass, per 100 parts by mass of the polymer main chain.

[0036] Examples of the metal salt include metal halides, metal sulfates, and metal nitrates. Among these, metal halides are preferred. Metal halides are easy to handle and can more easily form crosslinks with strength equivalent to that of sulfur crosslinks.

[0037] Examples of the metal halide include metal fluorides, metal chlorides, metal bromides, and metal iodides, and among these, metal chlorides are preferred. Metal chlorides are easy to handle and can more easily form crosslinks with strength equivalent to that of sulfur crosslinks.

[0038] Specific examples of the metal salt include FeCl2, FeCl2·4H2O, FeCl3, FeCl3·6H2O, etc. The metal salt may be a single type or a combination of two or more types.

[0039] (Method of producing complex polymer) The complex polymer of the present invention can be synthesized, for example, by reacting a polymer chain with a compound containing a nitrogen- and / or phosphorus-containing functional group to form a functionalized polymer in which the nitrogen- and / or phosphorus-containing functional group is bonded to the polymer chain, and then complexing the functionalized polymer with a metal ion of an element in Groups 7 to 10 of the Periodic Table. Here, the compound containing the nitrogen-containing functional group is preferably a compound containing a triazine ring or tetrazine ring as described above, and more preferably a compound represented by general formula (1). Furthermore, in the reaction between the polymer chain and the compound containing the nitrogen- and / or phosphorus-containing functional group, the reaction conditions, such as temperature, pressure, and time, are preferably selected appropriately depending on the type and reactivity of the polymer chain and the compound containing the nitrogen- and / or phosphorus-containing functional group used. Furthermore, in the complexation reaction between the functionalized polymer and the metal ion, the reaction conditions, such as temperature, pressure, and time, are preferably selected appropriately depending on the type and reactivity of the functionalized polymer and the metal ion used.

[0040] As an example, the reaction scheme for functionalizing the polymer main chain and complexing the functionalized polymer is shown below when 3,6-di(2-pyridyl)-1,2,4,5-tetrazine is used as the compound containing a nitrogen-containing functional group and iron chloride (FeCl2) is used as the source of the metal ion. [ka]

[0041] As shown in the upper part of the reaction scheme, in one embodiment of the present invention, a functionalized polymer is produced by the Diels-Alder reaction of a polymer chain containing conjugated diene units and / or olefin units with a compound containing a nitrogen-containing functional group. Note that, although nitrogen is eliminated during the Diels-Alder reaction in this embodiment, any other reaction may be used for the functionalization reaction.

[0042] As shown in the lower part of the above reaction scheme, in one embodiment of the present invention, a complexed polymer is produced by complexing a functionalized polymer with iron chloride. Note that, although the above reaction scheme shows a mode in which a nitrogen atom in a tetrazine residue, a nitrogen atom of a pyridyl group bonded to the tetrazine residue, and an iron ion are complexed, the complexed polymer of the present invention can take various complex forms.

[0043] The complex polymer may further have another functional group that does not complex with a metal ion of an element of Groups 7 to 10 of the periodic table. Such another functional group is not particularly limited and can be appropriately selected depending on the physical properties of the desired complex polymer.

[0044] The complexing polymer of the present invention may be prepared in advance by synthesis or the like as described above, but may also be generated in situ during the production process of the rubber composition, for example, as described in the section on the production method of the rubber composition below.

[0045] <Rubber composition> The rubber composition of the present invention includes the complex polymer described above. The rubber composition of the present invention is recyclable (e.g., remolding is possible by hot pressing) and has performance equivalent to that of a new product, since it includes the complex polymer.

[0046] The rubber composition of one embodiment of the present invention contains the complexed polymer as a rubber component. The rubber composition of the present invention may contain rubber components other than the complexed polymer. Examples of such rubber components include natural rubber (NR), synthetic diene rubber, and non-diene rubber. Examples of the synthetic diene rubber include synthetic isoprene rubber (IR), styrene-butadiene rubber (SBR), butadiene rubber (BR), styrene-isoprene rubber (SIR), chloroprene rubber (CR), ethylene-butadiene copolymer, and ethylene-styrene-butadiene copolymer. Examples of the non-diene rubber include silicone rubber, fluororubber, and urethane rubber. In addition, the rubber component of the rubber composition preferably contains the complex polymer in a proportion of 10% by mass or more, and the complex polymer may be contained in a proportion of 100% by mass.

[0047] When the polymer main chain contains olefin units but does not contain conjugated diene units, the complex polymer becomes a resin component. In this case, any rubber can be used as the rubber component of the rubber composition, and the rubber component can be the above-mentioned natural rubber (NR), synthetic diene rubber, non-diene rubber, etc. Furthermore, when the complex polymer is used as a resin composition, a thermoplastic resin can be used as the resin component. Examples of the thermoplastic resin that can be used include polyolefin resins, polyamide resins, polyester resins (PET, etc.), etc.

[0048] In addition to the complexing polymer and rubber component described above, the rubber composition of the present invention may contain compounding agents commonly used in the rubber industry, such as fillers (carbon black, silica, etc.), softeners, stearic acid, antioxidants, silane coupling agents, etc., selected and blended as appropriate within a range that does not impair the object of the present invention. Commercially available products can be suitably used as these compounding agents. The rubber composition of the present invention preferably contains a small amount of sulfur or peroxide, or does not contain any sulfur. Even when the rubber composition of the present invention contains a small amount of sulfur or does not contain any sulfur, the rubber composition of the present invention may contain a vulcanization accelerator, and preferably contains a vulcanization accelerator. The vulcanization accelerator preferably contains a sulfenamide-based vulcanization accelerator.

[0049] In one embodiment of the rubber composition of the present invention, the amount of sulfur in the rubber composition is preferably 0.3 parts by mass or less per 100 parts by mass of the rubber component, and the amount of sulfur may be 0. Since such a rubber composition has a low sulfur content, it has few sulfur-derived crosslinked structures (SS bonds, CS bonds, etc.) that are difficult to cleave once formed, and is therefore easy to recycle.

[0050] In another embodiment of the rubber composition of the present invention, the content of peroxide in the rubber composition is preferably 0.3 parts by mass or less per 100 parts by mass of the rubber component, and the content of the peroxide may be 0. Since such a rubber composition has a low peroxide content, it has few crosslinked structures (such as C-C bonds) caused by peroxides that are difficult to cleave once formed, and is easy to recycle.

[0051] In another embodiment of the rubber composition of the present invention, the amount of sulfur in the rubber composition is preferably 0.3 parts by mass or less per 100 parts by mass of the rubber component, and the amount of peroxide in the rubber composition is preferably 0.3 parts by mass or less per 100 parts by mass of the rubber component. Since such a rubber composition has low sulfur and peroxide contents, it has few crosslinked structures (SS bonds, CS bonds, CC bonds, etc.) derived from sulfur and peroxide, and is easy to recycle.

[0052] <Method of manufacturing rubber composition> The method for producing a rubber composition of the present invention is a method for producing a rubber composition containing the above-mentioned complex polymer. Note that the above-mentioned complex polymer may be produced during the production process of the rubber composition.

[0053] In one embodiment of the method for producing a rubber composition of the present invention, in a first stage of kneading, a polymer main chain and a compound containing a functional group are kneaded to form a functionalized polymer in which the functional group is bonded to the polymer main chain. In another embodiment of the method for producing a rubber composition of the present invention, in a second or subsequent stage of kneading, a metal salt is added and kneaded to complex the functionalized polymer to form a complexed polymer. This method for producing a rubber composition is highly productive because the complexed polymer can be prepared during the production of the rubber composition (kneading of the rubber composition). The complexation of the functionalized polymer by adding a metal salt can be carried out at any stage from the second stage onwards of the kneading. Furthermore, any compounding agent as described above may be simultaneously added in the first stage, second stage or later of the kneading. Furthermore, as the compound containing a functional group, the compound containing the above-mentioned triazine ring or tetrazine ring is preferred, and the compound represented by general formula (1) is more preferred.

[0054] The method for producing the rubber composition of the present invention is not limited to the above-mentioned method. For example, in another embodiment of the method for producing a rubber composition of the present invention, the complex polymer is formed in advance and the preformed complex polymer is blended during kneading. This method for producing a rubber composition can also easily produce a rubber composition containing the complex polymer, and is also excellent in productivity.

[0055] In another embodiment of the present invention, a method for producing a rubber composition includes preparing a functionalized polymer having a functional group bonded to a polymer main chain in advance, kneading the functionalized polymer with optional compounding ingredients in a first kneading stage, and then adding a metal salt and kneading the metal salt in a second or subsequent kneading stage to complex the functionalized polymer to form a complex polymer. This method for producing a rubber composition can also easily produce a rubber composition containing the complex polymer, and is also excellent in productivity.

[0056] <Rubber products> The rubber product of the present invention is characterized by containing the above-mentioned rubber composition. Since the rubber product of the present invention contains the above-mentioned rubber composition containing the recyclable complexed polymer, the rubber product is recyclable and has performance equivalent to that of a new product even after recycling.

[0057] The rubber product of the present invention is preferably a tire. The rubber portion of a tire has sufficient durability even after wear, and can be recycled as a tire by recycling the rubber portion. Examples of the application areas of the rubber composition in a tire include, but are not limited to, the tread, sidewall, side reinforcing rubber, and bead filler.

[0058] The tire can be manufactured, for example, by sequentially laminating components typically used in tire manufacturing, such as a carcass layer, a belt layer, and a tread layer, each made of a rubber composition, onto a tire building drum, removing the drum, and, if desired, heating the resulting mixture.

[0059] The rubber product of the present invention may be anything other than a tire, such as vibration-proof rubber, seismic isolation rubber, belts (conveyor belts), rubber crawlers, and various hoses. [Example]

[0060] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples in any way.

[0061] <Method of producing functionalized polymer A> In a glass bottle, 50 g of Asahi Kasei's "Tufden 2000R" (styrene-butadiene rubber (SBR), polymer backbone containing conjugated diene units) was dissolved in 600 mL of THF. 3,6-di(2-pyridyl)-1,2,4,5-tetrazine (Tokyo Chemical Industry Co., Ltd., 2.4 g, 10 mmol) was added to the glass bottle and heated under reflux for 3 hours. The resulting solution was dried under reduced pressure at 60°C for 7 hours to obtain 50 g of functionalized polymer A. The amount of functional groups capable of complexing with metal ions in the obtained functionalized polymer A was 1.2 mol % relative to the monomer units in the polymer main chain.

[0062] <Method of producing functionalized polymer B> In a glass bottle, 50 g of Asahi Kasei "Tufden 2000R" (styrene-butadiene rubber (SBR), polymer backbone containing conjugated diene units) was dissolved in 600 mL of THF. 3,6-di(2-pyridyl)-1,2,4,5-tetrazine (Tokyo Chemical Industry Co., Ltd., 1.8 g, 7.5 mmol) and 4-phenyl-1,2,4-triazoline-3,5-dione (Tokyo Chemical Industry Co., Ltd., 0.44 g, 0.25 mmol) were added to the glass bottle and heated to reflux for 3 hours. The resulting solution was dried under reduced pressure at 60 °C for 7 hours to obtain 50 g of functionalized polymer B. The amount of functional groups capable of complexing with metal ions in the obtained functionalized polymer B was 0.9 mol % relative to the monomer units in the polymer main chain.

[0063] <Production of Rubber Composition> A rubber composition was produced using a conventional Banbury mixer according to the formulation shown in Table 1. Mixing was performed in the first and second mixing stages, and in the examples, iron (II) chloride tetrahydrate was added in the second mixing stage to form a complex polymer. The first mixing stage was performed at 140°C for 3 minutes, and the second mixing stage was performed at 80°C for 1 minute. The tensile strength (Tb) and elongation at break (Eb) of the resulting rubber composition were measured using the following methods.

[0064] Regarding the complexing polymer in the rubber compositions produced in Examples 1 to 4, the bond dissociation energy between iron ions and nitrogen-containing functional groups is 249.7 kJ / mol.

[0065] <Measurement of Tb and Eb> JIS No. 7 dumbbell-shaped test pieces were prepared from the rubber composition, and tensile strength (Tb (MPa)) and elongation at break (Eb (%)) were measured by conducting a tensile test at room temperature (23°C) and high temperature (100°C) in accordance with JIS K6251.

[0066] <Recycling of Rubber Composition> The obtained rubber composition was put into a mold and heated at 160°C for 3 minutes for remolding. For the remolded rubber composition, Tb and Eb were measured by the above method. Also, remolding was carried out a total of 3 times, and the recyclability of each rubber composition was evaluated. The results are shown in Table 1. In Table 1, "not possible" indicates that remolding could not be carried out even once, and "3 times or more" indicates that remolding could be carried out 3 times.

[0067]

Table 1

[0068] *1 Polymer: Manufactured by Asahi Kasei Corporation, "Tufdene 2000R", styrene-butadiene rubber (SBR) *2 Functionalized Polymer A: Synthesized by the above method *3 Functionalized Polymer B: Synthesized by the above method *4 Silica: Manufactured by Tosoh Silica Corporation, "Nipsil AQ" *5 Carbon Black: Manufactured by Tokai Carbon Co., Ltd., "N234" *6 Oil: Manufactured by JX Nippon Oil & Energy Corporation, "JOMO PROCESS NC300BN" *7 Wax: Manufactured by Seiko Chemical Co., Ltd., "Santite A" *8 Antioxidant: Manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "No Crack 6C" *9 Silane Coupling Agent: Bis(triethoxysilylpropyl) polysulfide *10 Vulcanization accelerator A: Bis(2-benzothiazolyl) persulfide *11 Vulcanization accelerator B: N-tert-butyl-2-benzothiazolyl sulfenamide *12 Vulcanization accelerator C: Diphenyl guanidine

[0069] It can be seen from Table 1 that the rubber compositions of the examples according to the present invention have physical properties (tensile properties) equivalent to those of the rubber compositions of the comparative examples that utilize sulfur crosslinking. In particular, it can be seen that the rubber compositions of the examples according to the present invention also have physical properties (tensile properties) at high temperatures (100°C) equivalent to those of the rubber compositions of the comparative examples that utilize sulfur crosslinking. Furthermore, it can be seen from Table 1 that the rubber compositions of the examples according to the present invention can be remolded (recycled), and furthermore, the physical properties after remolding (recycled) are equivalent to those of new products. [Industrial Applicability]

[0070] The complexed polymer and rubber composition of the present invention can be used in various rubber products such as tires.

Claims

1. a polymer backbone comprising conjugated diene units and / or olefin units, and functional groups attached to the polymer backbone; A tire including a rubber composition containing a complexed polymer, wherein the functional group contains a nitrogen atom and is complexed with a metal ion of an element of Groups 7 to 10 of the periodic table, the complex polymer has a bond dissociation energy between the metal ion and the functional group of 200 kJ / mol or more, the functional group is derived from a compound containing a triazine ring or a tetrazine ring, and a pyridyl group or a pyrimidinyl group is bonded to the triazine ring or the tetrazine ring; The tire, wherein the amount of sulfur in the rubber composition is 0.3 parts by mass or less per 100 parts by mass of the rubber component.

2. The tire according to claim 1 , wherein the complexing polymer has the metal ions and the functional groups bonded together by coordinate bonds.

3. The tire according to claim 1 , wherein the complex polymer has two pyridyl groups or two pyrimidinyl groups bonded to the triazine ring or the tetrazine ring.

4. The complexing polymer has a functional group represented by the following general formula (1): 【Chemistry 1】 [In the formula, X １ and X ２ are each independently a pyridyl group or a pyrimidinyl group, and Y １ and Y ２ and each independently represents a single bond or a divalent hydrocarbon group.

5. The complexing polymer is represented by X in the general formula (1). １ and X ２ is a pyridyl group, and Y １ and Y ２ 5. The tire of claim 4, wherein is a single bond.

6. The tire according to any one of claims 1 to 5, wherein the metal ions in the complexing polymer are metal ions of elements in Group 8 of the periodic table.

7. 7. The tire of claim 6, wherein the complexing polymer has a metal ion that is an iron ion.

8. The tire according to any one of claims 1 to 7, wherein the metal ions are complexed by adding a metal salt to the polymer backbone to which the functional groups are attached.

9. 9. The tire of claim 8, wherein the metal salt is a metal halide.

10. 10. The tire of claim 9, wherein the metal salt is a metal chloride.

11. The tire according to any one of claims 1 to 10, wherein the complex polymer has the functional groups bonded in an amount of 0.1 to 10 mol % relative to the monomer units in the polymer main chain.

12. The tire according to any one of claims 1 to 11, wherein the rubber composition has a peroxide content of 0.3 parts by mass or less per 100 parts by mass of the rubber component.

13. The tire according to any one of claims 1 to 11, wherein the amount of sulfur in the rubber composition is 0 parts by mass per 100 parts by mass of the rubber component.

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