Rubber composition and rubber product

Abstract

The present invention provides a rubber composition that can improve the balance between low strain hysteresis loss and high strain hysteresis loss of a rubber. This rubber composition contains a rubber component and at least one type of compound selected from the group consisting of general formulae (1) and (2). General formula (1): HS-R-COOM General formula (2): MOCO-R-(S) n-R-COOM (In the formulae: R moieties are each independently a linear or branched hydrocarbylene group in which the number of carbon atoms in a linear portion connecting a sulfur atom to a COOM group is 8 or more; M moieties are each independently an atom selected from the group consisting of alkali metals and alkaline earth metals; and n is an integer from 2 to 8.)

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority from Japanese Patent Application No. 2020-080713, filed on April 30, 2020, the contents of which are incorporated herein by reference. [Technical field]

[0002] The present invention relates to a rubber composition and a rubber product. [Background technology]

[0003] Rubber hysteresis loss (hereinafter sometimes simply referred to as "loss") is the energy lost due to the history of rubber deformation, and refers to the difference between the energy added during the deformation process of the material and the energy returned during the recovery process. This difference is converted into heat or sound, etc. Therefore, rubber hysteresis loss is known to have a significant impact on, for example, the fuel efficiency of tires and the damping properties of vibration isolation rubber.

[0004] For example, Patent Document 1 discloses a method for producing a rubber composition having small hysteresis loss, low heat build-up, and improved abrasion resistance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2013-108003 A Summary of the Invention [Problem to be solved by the invention]

[0006] By reducing the loss of rubber at low strain, the rubber will have lower heat generation (i.e., be more fuel efficient), but if the loss of rubber at high strain is also reduced, the energy dissipation ability will decrease, which may lead to reduced durability. Conversely, if the loss is increased to increase durability, the loss at low strain will increase, which may lead to poor heat generation.

[0007] Therefore, an object of the present invention is to provide a rubber composition capable of improving the balance between the hysteresis loss at low strain and the hysteresis loss at high strain of rubber. [Means for solving the problem]

[0008] The rubber composition according to the present invention comprises: A rubber component, At least one compound selected from the group consisting of the following general formulas (1) and (2), The rubber composition comprises: HS-R-COOM ···(1) MOCO-R-(S) n -R-COOM ···(2) (In the formula, R is independently a linear or branched hydrocarbylene group having 8 or more carbon atoms in the linear portion connecting the sulfur atom and the COOM group; M is independently an atom selected from the group consisting of alkali metals and alkaline earth metals; n is an integer from 2 to 8. This makes it possible to improve the balance between the hysteresis loss at low strain and the hysteresis loss at high strain of the rubber.

[0009] A rubber product according to the present invention is a rubber product produced using any one of the rubber compositions described above, which has an excellent balance between hysteresis loss at low strain and hysteresis loss at high strain. Effect of the Invention

[0010] According to the present invention, it is possible to provide a rubber composition capable of improving the balance between the hysteresis loss at low strain and the hysteresis loss at high strain of rubber. According to the present invention, it is possible to provide a rubber product having an excellent balance between the hysteresis loss at low strain and the hysteresis loss at high strain. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present invention will be described. These descriptions are intended to be illustrative of the present invention and are not intended to limit the present invention in any way.

[0012] In the present invention, two or more embodiments can be combined in any desired manner.

[0013] In this specification, unless otherwise specified, numerical ranges are intended to include the lower and upper limits of the range. For example, 20 to 150 parts by mass means 20 parts by mass or more and 150 parts by mass or less.

[0014] (Rubber composition) The rubber composition according to the present invention comprises: A rubber component, At least one compound selected from the group consisting of the following general formulas (1) and (2), The rubber composition comprises: HS-R-COOM ···(1) MOCO-R-(S) n -R-COOM ···(2) (In the formula, R is independently a linear or branched hydrocarbylene group having 8 or more carbon atoms in the linear portion connecting the sulfur atom and the COOM group; M is independently an atom selected from the group consisting of alkali metals and alkaline earth metals; n is an integer from 2 to 8.

[0015] The rubber component of the rubber composition according to the present invention and the compounds of the general formulae (1) and (2) will be illustrated below.

[0016] Rubber components The rubber component is not particularly limited, and a rubber component of a known rubber composition can be used. Examples of the rubber component include natural rubber (NR), synthetic isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), butyl rubber (IIR), chloroprene rubber, ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), polysulfide rubber, silicone rubber, fluororubber, and urethane rubber. The rubber component may be modified or unmodified.

[0017] The rubber component may be a diene polymer known in the art for use in rubber compositions.

[0018] The rubber component may be used alone or in combination of two or more kinds.

[0019] In one embodiment, the rubber component is at least one selected from the group consisting of NR, IR, BR, SBR, and modifications thereof.

[0020] When SBR is used as the rubber component, the styrene content in SBR is not particularly limited and can be adjusted appropriately. The styrene content in SBR is, for example, in the range of more than 0% by weight and less than 50% by weight. In one embodiment, the styrene content in SBR is more than 0% by weight, and is 1% by weight or more, 3% by weight or more, 5% by weight or more, 10% by weight or more, 15% by weight or more, 20% by weight or more, 30% by weight or more, or 40% by weight or more. In another embodiment, the styrene content in SBR is 50% by weight or less, 45% by weight or less, 40% by weight or less, 30% by weight or less, 20% by weight or less, 15% by weight or less, 10% by weight or less, or 5% by weight or less.

[0021] When SBR is used as the rubber component, the vinyl content of the butadiene part of SBR is not particularly limited and can be adjusted appropriately. The vinyl content of the butadiene part of SBR is, for example, 1 mol% to 70 mol%. In one embodiment, the vinyl content of the butadiene part of SBR is 1 mol% or more, 5 mol% or more, 10 mol% or more, 20 mol% or more, 30 mol% or more, 35 mol% or more, 40 mol% or more, 45 mol% or more, 50 mol% or more, or 60 mol% or more. In another embodiment, the vinyl content of the butadiene part of SBR is 70 mol% or less, 60 mol% or less, 50 mol% or less, 45 mol% or less, 40 mol% or less, 35 mol% or less, 30 mol% or less, 20 mol% or less, 10 mol% or less, or 5 mol% or less.

[0022] The weight average molecular weight (Mw) of the rubber component is not particularly limited and can be adjusted appropriately. The Mw of the rubber component is, for example, 10,000 to 10,000,000. In one embodiment, the Mw of the rubber component is 10,000 or more, 50,000 or more, 100,000 or more, 150,000 or more, 200,000 or more, 250,000 or more, 300,000 or more, 400,000 or more, 500,000 or more, 1,000,000 or more, or 5,000,000 or more. In another embodiment, the Mw of the rubber component is 10,000,000 or less, 5,000,000 or less, 4,000,000 or less, 3,000,000 or less, 2,000,000 or less, 1,000,000 or less, 500,000 or less, 400,000 or less, 300,000 or less, 250,000 or less, 200,000 or less, 150,000 or less, or 100,000 or less.

[0023] The Mw of the rubber component can be obtained by measuring using gel permeation chromatography and converting it into a monodisperse polystyrene equivalent.

[0024] Compounds of general formulas (1) and (2) In the rubber composition according to the present invention, the compounds of general formulas (1) and (2) have the function of improving the balance between loss at low strain and loss at high strain when compounded together with the rubber component. HS-R-COOM ···(1) MOCO-R-(S) n -R-COOM ···(2) (In the formula, R is independently a linear or branched hydrocarbylene group having 8 or more carbon atoms in the linear portion connecting the sulfur atom and the COOM group; M is independently an atom selected from the group consisting of alkali metals and alkaline earth metals; n is an integer from 2 to 8.

[0025] Without wishing to be bound by theory, the reason for improving the above balance is presumed to be, for example, as follows: (i) the sulfur atoms in the compounds of general formulas (1) and (2) react with the rubber component to introduce COOM groups into the rubber component; (ii) Between the polymer networks of the rubber component, M of multiple COOM groups and the COO moieties of COOM groups are coordinated to form non-covalent bonds; (iii) In a vulcanized rubber composition or rubber product, at low strain, in addition to the sulfur-sulfur bonds formed by vulcanization, the non-covalent bonds fix the network and suppress the occurrence of loss, whereas at high strain, the weak non-covalent bonds are cleaved, increasing energy dissipation and improving the durability of the rubber. When the strain is released, the non-covalent bonds are formed again, making the rubber responsive to both low and high strain.

[0026] In the compounds of general formulae (1) and (2), R is independently a linear or branched hydrocarbylene group having 8 or more carbon atoms in the linear portion connecting the sulfur atom and the COOM group. For example, in the case of a linear hydrocarbylene group having 8 carbon atoms, the structure of the compound of general formula (1) is HS-(CH2)8-COOM. R may also be a branched hydrocarbylene group as long as the linear portion connecting the sulfur atom and the COOM group has 8 or more carbon atoms. For example, in the case of the structure HS-CH(CH3)-(CH2)7-COOM, R is a hydrocarbylene group having 8 carbon atoms in the linear portion connecting the sulfur atom and the COOM group and branched at the carbon adjacent to the sulfur atom.

[0027] The number of carbon atoms in the straight-chain portion connecting the sulfur atom and the COOM group in R of the compounds of general formulas (1) and (2) is, for example, 8 to 30. In one embodiment, the number of carbon atoms in the straight-chain portion connecting the sulfur atom and the COOM group in R of the compounds of general formulas (1) and (2) is 8 or more, 10 or more, 12 or more, 14 or more, 16 or more, 18 or more, 20 or more, 22 or more, 24 or more, 26 or more, or 28 or more. In another embodiment, the number of carbon atoms in the straight-chain portion connecting the sulfur atom and the COOM group in R of the compounds of general formulas (1) and (2) is 30 or less, 28 or less, 26 or less, 24 or less, 22 or less, 20 or less, 18 or less, 16 or less, 14 or less, 12 or less, or 10 or less.

[0028] In one embodiment, the number of carbon atoms in the linear portion connecting the sulfur atom and the COOM group in R of the compounds of general formulas (1) and (2) is 10 or more. This makes the compound more easily mixable with the rubber component and efficiently reacts with the rubber component.

[0029] When R of the compounds of general formulas (1) and (2) is a branched hydrocarbylene group, the total number of carbons in the hydrocarbylene group is, for example, 9 to 50. In one embodiment, when R of the compounds of general formulas (1) and (2) is a branched hydrocarbylene group, the total number of carbons in the hydrocarbylene group is 9 or more, 10 or more, 15 or more, 20 or more, 25 or more, 30 or more, 35 or more, 40 or more, or 45 or more. In another embodiment, when R of the compounds of general formulas (1) and (2) is a branched hydrocarbylene group, the total number of carbons in the hydrocarbylene group is 50 or less, 45 or less, 40 or less, 35 or less, 30 or less, 25 or less, 20 or less, 15 or less, or 10 or less.

[0030] In one embodiment, when R in the compounds of general formulas (1) and (2) is a branched hydrocarbylene group, the number of carbon atoms in the linear portion connecting the sulfur atom and the COOM group is greater than the number of carbon atoms in the branched chain branching from the linear chain.

[0031] In one embodiment, R is a linear hydrocarbylene group.

[0032] In one embodiment, R in the compounds of general formulas (1) and (2) is a branched hydrocarbylene group branched at the carbon adjacent to the sulfur atom, such as, for example, HS-CH(CH3)-(CH2)7-COOM.

[0033] In one embodiment, R in the compounds of general formulas (1) and (2) is a branched hydrocarbylene group that branches at the carbon next to the sulfur atom, such as, for example, HS-(CH2)-CH(CH3)-(CH2)6-COOM.

[0034] In one embodiment, R in the compounds of general formulas (1) and (2) is a branched hydrocarbylene group that is branched at 3, 4, 5, 6, 7, or 8 carbons adjacent to the sulfur atom.

[0035] In one embodiment, the compounds of general formulas (1) and (2) do not include compounds that are branched from the carbon adjacent to the sulfur atom, in another embodiment, the compounds of general formulas (1) and (2) are branched at two or more carbons adjacent to the sulfur atom.

[0036] In the compound of general formula (2), the two R's may be the same or different.

[0037] In the compounds of general formulas (1) and (2), M is an atom independently selected from the group consisting of alkali metals and alkaline earth metals. Examples of M include Li, Na, K, Rb, Cs, Fr; Mg, Ca, Sr, Ba, and Ra. In one embodiment, in the compounds of general formulas (1) and (2), M is independently at least one selected from the group consisting of Li, Na, and K. From the viewpoint of the balance between the hysteresis loss at low strain and the hysteresis loss at high strain, M is preferably Na.

[0038] In the present invention, M in the compounds of general formulas (1) and (2) is an atom selected from the group consisting of alkali metals and alkaline earth metals. As a result, as described above, it is presumed that M of multiple COOM groups and the COO moiety of the COOM group are coordinated to form a non-covalent bond between the polymer networks of the rubber component. Therefore, when a compound having a carboxyl (COOH) group other than a carboxylate is used, a non-covalent bond by this coordination is not formed, and only a weaker non-covalent bond by the carboxyl group remains, which may make it difficult to suppress the occurrence of loss at low strain.

[0039] In one embodiment, M in R of the compounds of general formulas (1) and (2) is Na.

[0040] In the compound of general formula (2), the two M's may be the same or different.

[0041] In the general formula (2), n is an integer selected from 2, 3, 4, 5, 6, 7 and 8.

[0042] In one embodiment, n in the compound of general formula (2) is 2-4.

[0043] In one embodiment, the rubber composition according to the present invention comprises a compound of general formula (1). In another embodiment, the rubber composition according to the present invention comprises a compound of general formula (2). In another embodiment, the rubber composition according to the present invention comprises compounds of general formulas (1) and (2). In another embodiment, the rubber composition according to the present invention comprises a compound of general formula (1) and does not comprise a compound of general formula (2). In another embodiment, the rubber composition according to the present invention comprises a compound of general formula (2) and does not comprise a compound of general formula (1).

[0044] In one embodiment, the compound of general formula (1) is HS-(CH2)8-COOLi, HS-(CH2)8-COONa, HS-(CH2)8-COOK, HS-(CH2)8-COOMg, HS-(CH2)8-COOCa, HS-(CH2) 10 -COOLi, HS-(CH2) 10-COONa, HS-(CH2) 10 -COOK, HS-(CH2) 10 -COOMg, HS-(CH2) 10 -COOCa, HS-(CH2) 12 -COOLi, HS-(CH2) 12 -COONa, HS-(CH2) 12 -COOK, HS-(CH2) 12 -COOMg, HS-(CH2) 12 -COOCa, HS-(CH2) 14 -COOLi, HS-(CH2) 14 -COONa, HS-(CH2) 14 -COOK, HS-(CH2) 14 -COOMg, HS-(CH2) 14 -COOCa, HS-(CH2) 16 -COOLi, HS-(CH2) 16 -COONa, HS-(CH2) 16 -COOK, HS-(CH2) 16 -COOMg, HS-(CH2) 16 -COOCa, HS-(CH2) 18 -COOLi, HS-(CH2) 18 -COONa, HS-(CH2) 18 -COOK, HS-(CH2) 18 -COOMg, and HS-(CH2) 18 -COOCa.

[0045] In one embodiment, the compound of general formula (2) is LiOCO-(CH2)8-(S)2-(CH2)8-COOLi, NaOCO-(CH2)8-(S)2-(CH2)8-COONa, KOCO-(CH2)8-(S)2-(CH2)8-COOK, MgOCO-(CH2)8-(S)2-(CH2)8-COOMg, CaOCO-(CH2)8-(S)2-(CH2)8-COOCa, LiOCO-(CH2) 10 -(S)2-(CH2) 10 -COOLi, NaOCO-(CH2) 10 -(S)2-(CH2) 10-COONa、KOCO-(CH2) 10 -(S)2-(CH2) 10 -COOK、MgOCO-(CH2) 10 -(S)2-(CH2) 10 -COOMg、CaOCO-(CH2) 10 -(S)2-(CH2) 10 -COOCa、LiOCO-(CH2) 12 -(S)2-(CH2) 12 -COOLi、NaOCO-(CH2) 12 -(S)2-(CH2) 12 -COONa、KOCO-(CH2) 12 -(S)2-(CH2) 12 -COOK、MgOCO-(CH2) 12 -(S)2-(CH2) 12 -COOMg、CaOCO-(CH2) 12 -(S)2-(CH2) 12 -COOCa、LiOCO-(CH2) 14 -(S)2-(CH2) 14 -COOLi、NaOCO-(CH2) 14 -(S)2-(CH2) 14 -COONa、KOCO-(CH2) 14 -(S)2-(CH2) 14 -COOK、MgOCO-(CH2) 14 -(S)2-(CH2) 14 -COOMg、CaOCO-(CH2) 14 -(S)2-(CH2) 14 -COOCa、LiOCO-(CH2) 16 -(S)2-(CH2) 16 -COOLi、NaOCO-(CH2) 16 -(S)2-(CH2) 16 -COONa、KOCO-(CH2) 16 -(S)2-(CH2) 16 -COOK、MgOCO-(CH2) 16 -(S)2-(CH2) 16 -COOMg、CaOCO-(CH2) 16 -(S)2-(CH2) 16 -COOCa、LiOCO-(CH2)18 -(S)2-(CH2) 18 -COOLi, NaOCO-(CH2) 18 -(S)2-(CH2) 18 -COONa, KOCO-(CH2) 18 -(S)2-(CH2) 18 -COOK, MgOCO-(CH2) 18 -(S)2-(CH2) 18 -COOMg, and CaOCO-(CH2) 18 -(S)2-(CH2) 18 -COOCa.

[0046] The compound of formula (1) may be used alone or in combination of two or more kinds.

[0047] The compound of formula (2) may be used alone or in combination of two or more kinds.

[0048] The total amount of at least one compound selected from the group consisting of general formulas (1) and (2) in the rubber composition is, for example, 2 to 20 mmol of COOM groups per 100 g of the rubber component. In one embodiment, the total amount of at least one compound selected from the group consisting of general formulas (1) and (2) in the rubber composition is 2 mmol or more, 3 mmol or more, 4 mmol or more, 5 mmol or more, 6 mmol or more, 7 mmol or more, 8 mmol or more, 9 mmol or more, 10 mmol or more, 12 mmol or more, 14 mmol or more, 16 mmol or more, or 18 mmol or more per 100 g of the rubber component. In another embodiment, the total amount of at least one compound selected from the group consisting of general formulas (1) and (2) in the rubber composition is 20 mmol or less, 18 mmol or less, 16 mmol or less, 14 mmol or less, 12 mmol or less, 10 mmol or less, 9 mmol or less, 8 mmol or less, 7 mmol or less, 6 mmol or less, 5 mmol or less, 4 mmol or less, or 3 mmol or less, per 100 g of the rubber component.

[0049] The rubber composition according to the present invention may contain known components used in rubber compositions in addition to the rubber component and the compound of the above general formula. Examples of such known components include fillers such as silica and carbon black; vulcanizing agents (crosslinking agents), vulcanization accelerators, vulcanization retarders, antiaging agents, stearic acid, zinc oxide, reinforcing agents, softeners, vulcanization aids, colorants, flame retardants, lubricants, foaming agents, thermoplastic resins, thermosetting resins, plasticizers, processing aids, antioxidants, scorch inhibitors, ultraviolet inhibitors, antistatic agents, coloring inhibitors, and oils. These may be used alone or in combination of two or more.

[0050] Fillers As the filler, known fillers such as carbon black and silica can be appropriately selected and used.

[0051] (Carbon Black) The carbon black is not particularly limited and can be appropriately selected according to the purpose. For example, FEF, SRF, HAF, ISAF, SAF grade carbon black can be used. Carbon black may be used alone or in combination of two or more kinds.

[0052] The nitrogen adsorption specific surface area (N2SA) of the carbon black is not particularly limited and is, for example, 20 to 250 m 2 The N2SA of carbon black is measured in accordance with JIS K 6217-2:2001.

[0053] (silica) The silica is not particularly limited, and for example, general grade silica, special silica surface-treated with a silane coupling agent, etc., can be used depending on the application.

[0054] The silica may be used alone or in combination of two or more kinds.

[0055] Examples of silica include wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), calcium silicate, and aluminum silicate. Among these, wet silica is preferred.

[0056] The wet silica may be precipitated silica, which is obtained by growing primary silica particles by reacting the reaction solution at a relatively high temperature in a neutral to alkaline pH range in the early stages of production, and then agglomerating the primary particles by controlling the pH to the acidic side.

[0057] The cetyltrimethylammonium bromide adsorption specific surface area (CTAB specific surface area) of silica is not particularly limited and can be appropriately adjusted. The CTAB specific surface area of ​​silica is, for example, 70 to 250 m 2 / g.

[0058] In this specification, the CTAB specific surface area refers to a value measured in accordance with ASTM D3765-92, provided that the adsorption cross section per molecule of cetyltrimethylammonium bromide on a silica surface is 0.35 nm 2 The specific surface area (m2) calculated from the amount of CTAB adsorbed is 2 / g) is the specific surface area of ​​CTAB.

[0059] The BET specific surface area of ​​silica is not particularly limited and can be appropriately adjusted. The BET specific surface area of ​​silica is, for example, 100 to 250 m 2 / g.

[0060] In this specification, the BET specific surface area refers to a specific surface area determined by the BET method. The BET specific surface area can be measured in accordance with ASTM D4820-93.

[0061] The amount of the filler in the rubber composition is, for example, 20 to 150 parts by mass per 100 parts by mass of the rubber component.

[0062] In one embodiment, the amount of the filler is 20 parts by mass or more, 30 parts by mass or more, 40 parts by mass or more, 50 parts by mass or more, 60 parts by mass or more, 70 parts by mass or more, 80 parts by mass or more, 90 parts by mass or more, 100 parts by mass or more, 110 parts by mass or more, 120 parts by mass or more, 130 parts by mass or more, or 140 parts by mass or more, based on 100 parts by mass of the rubber component. In another embodiment, the amount of the filler is 150 parts by mass or less, 140 parts by mass or less, 130 parts by mass or less, 120 parts by mass or less, 110 parts by mass or less, 100 parts by mass or less, 90 parts by mass or less, 80 parts by mass or less, 70 parts by mass or less, 60 parts by mass or less, 50 parts by mass or less, 40 parts by mass or less, or 30 parts by mass or less, based on 100 parts by mass of the rubber component.

[0063] Method for preparing rubber composition The method for preparing the rubber composition is not particularly limited, except that the rubber composition contains the rubber component and the compound of the general formula, and any known method for preparing a rubber composition can be used.

[0064] For example, when the preparation of a rubber composition includes a non-production process (also referred to as a non-professional kneading process) and a production process (also referred to as a professional kneading process), the rubber component not including a vulcanization system (vulcanizing agent and vulcanization accelerator); some or all of the compounds of the general formula; a filler; and other components such as stearic acid may be kneaded in the non-production process, and the vulcanization system and zinc oxide, etc. may be added to the kneaded product from the non-production process and the mixture may be kneaded to prepare the rubber composition in the production process.

[0065] In one embodiment, when the preparation of the rubber composition includes a non-production step and a production step, all of the compound of the general formula is added in the non-production step. In another embodiment, when the preparation of the rubber composition includes a non-production step and a production step, a portion of the compound of the general formula is added in the non-production step and the remaining compound of the general formula is added in the production step.

[0066] When the preparation of the rubber composition includes a non-production step and a production step, the non-production step may be only one stage or may be two stages.

[0067] (Rubber products) The rubber product according to the present invention is a rubber product produced using any one of the rubber compositions described above. Examples of the rubber product include tires, anti-vibration rubber, vibration-isolating rubber, hoses, belts such as conveyor belts, rubber pads (MT pads), rubber crawlers, bellows (air springs), pneumatic chucks such as air pickers and air grippers, rubber bearings such as rubber bearings for bridges, rubber-covered chain-type bridge fall prevention devices, and rubber for office equipment such as OA rollers.

[0068] In one embodiment, the rubber product is at least one selected from the group consisting of tires; vibration-proof rubber; vibration-isolating rubber; hoses; belts such as conveyor belts; rubber pads (MT pads); rubber crawlers; bellows (air springs); pneumatic chucks such as air pickers and air grippers; rubber bearings such as rubber bearings for bridges; rubber-coated chain-type bridge fall prevention devices; and rubber for office equipment such as OA rollers.

[0069] ·tire The tire according to the present invention is a tire using any one of the rubber compositions described above.

[0070] The tire is not particularly limited except that any of the above rubber compositions is used, and a known tire configuration and manufacturing method can be adopted. Examples of components in a tire include a tread portion, a shoulder portion, a sidewall portion, a bead portion, a belt layer, and a carcass. EXAMPLES

[0071] The present invention will be described in more detail below with reference to examples, but these examples are intended to illustrate the present invention and are not intended to limit the present invention in any way. In the examples, the blend amounts refer to parts by mass unless otherwise specified.

[0072] Details of the materials used in the examples are as follows: Styrene butadiene rubber (SBR): styrene content 10% by weight, vinyl content 40 mol%, number average molecular weight 201,000, weight average molecular weight 211,000 Compound of general formula (1): SH(CH2) 10 COONa Comparison compound 1: SHCH2COONa Comparison compound 2: SH(CH2) 10 COOH Filler: Carbon black, manufactured by Tokai Carbon Co., Ltd., "Seast7HM" N234 Wax: "Suntite" manufactured by Seiko Chemical Co., Ltd. Anti-aging agent: "Nocrac 6C" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 1: Bis(2-benzothiazolyl) persulfide Accelerator 2: N-tert-butyl-2-benzothiazole sulfenamide

[0073] Example 1 A non-production process and a production process were carried out to obtain vulcanized rubber with the composition shown in Table 1. In the non-production process, the maximum temperature of the rubber composition was adjusted to 150°C. In the production process, the maximum temperature of the rubber composition was adjusted to 110°C. The compound of general formula (1) was blended in an amount such that the number of moles of COONa groups was 5 mmol per 100 g of SBR. (Comparative Examples 1 to 3) A vulcanized rubber was obtained in the same manner as in Example 1, except that the formulation of the rubber composition was changed to the formulation shown in Table 1. In Comparative Examples 2 and 3, the comparative compounds were blended so that the number of moles of COONa groups or COOH groups in the comparative compounds was equal to the number of moles of COONa groups in the compound of general formula (1) in Example 1.

[0074] The resulting vulcanized rubber was subjected to the following hysteresis loss measurement.

[0075] Hysteresis loss measurement A universal material testing machine (manufactured by Instron) was used to measure the rate of energy loss by carrying out a loading-unloading test at a temperature of 25°C, 10% or 300% strain, and a speed of 200 mm / sec. The hysteresis loss of each of the examples and comparative examples was indexed, with the hysteresis loss of Comparative Example 1 being set at 100. The results are shown in Table 1. A smaller hysteresis loss at 10% strain indicates better low heat generation properties. A larger hysteresis loss at 300% strain indicates better durability.

[0076] [Table 1]

[0077] From Table 1, it is seen that the vulcanized rubber using the rubber composition according to the present invention can improve the balance between the hysteresis loss at low strain and the hysteresis loss at high strain. [Industrial Applicability]

[0078] According to the present invention, it is possible to provide a rubber composition capable of improving the balance between the hysteresis loss at low strain and the hysteresis loss at high strain of rubber. According to the present invention, it is possible to provide a rubber product having an excellent balance between the hysteresis loss at low strain and the hysteresis loss at high strain.

Claims

1. A rubber component, At least one compound selected from the group consisting of the following general formulas (1) and (2), A rubber composition comprising: HS-R-COOM...(1) MOCO-R-(S) n -R-COOM ・・・(2) (In the formula, R is independently a linear or branched hydrocarbylene group having 8 or more carbon atoms in the linear portion connecting the sulfur atom and the COOM group; M is independently an atom selected from the group consisting of alkali metals and alkaline earth metals; n is an integer from 2 to 8.

2. The rubber composition according to claim 1 , wherein the carbon number is 10 or more.

3. The rubber composition according to claim 1 or 2, wherein R is a linear hydrocarbylene group.

4. The rubber composition according to any one of claims 1 to 3, wherein M is at least one selected from the group consisting of Li, Na and K.

5. The rubber composition according to any one of claims 1 to 4, wherein M is Na.

6. The rubber composition according to any one of claims 1 to 5, wherein a total amount of COOM groups in the compound is 2 to 20 mmol per 100 g of the rubber component.

7. The rubber composition according to any one of claims 1 to 6, further comprising a filler, the amount of the filler being 20 to 150 parts by mass per 100 parts by mass of the rubber component.

8. The method includes a non-production process and a production process, In the non-production step, a rubber component and at least a part of at least one compound selected from the group consisting of the following general formulas (1) and (2) are kneaded to form a kneaded product, HS-R-COOM...(1) MOCO-R-(S) n -R-COOM ・・・(2) (In the formula, R is independently a linear or branched hydrocarbylene group having 8 or more carbon atoms in the linear portion connecting the sulfur atom and the COOM group; M is independently an atom selected from the group consisting of alkali metals and alkaline earth metals; n is an integer from 2 to 8. In the production step, a vulcanization system is added to the kneaded material from the non-production step, and the kneaded material is kneaded to produce a rubber composition.

9. The method for producing a rubber composition according to claim 8 , wherein the number of carbon atoms is 10 or more.

10. The method for producing a rubber composition according to claim 8 or 9, wherein R is a linear hydrocarbylene group.

11. The method for producing a rubber composition according to any one of claims 8 to 10, wherein M is at least one selected from the group consisting of Li, Na and K.

12. The method for producing a rubber composition according to any one of claims 8 to 11, wherein M is Na.

13. The method for producing a rubber composition according to any one of claims 8 to 12, wherein a total amount of COOM groups in the compound is 2 to 20 mmol per 100 g of the rubber component.

14. The method for producing a rubber composition according to any one of claims 8 to 13, further comprising adding a filler in the non-production step, wherein an amount of the filler is 20 to 150 parts by mass per 100 parts by mass of the rubber component.

15. A rubber product produced using the rubber composition according to any one of claims 1 to 7.

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