Reconditioned tires

Abstract

To provide a retreaded tire that uses a resin-based adhesive while suppressing a decrease in ride comfort performance. [Solution] A retreaded tire comprising a base tire, a tread member, and an adhesive layer, wherein the adhesive layer is disposed between the base tire and the tread member, the tread member is made of a rubber composition, the adhesive layer is made of a resin-based adhesive, the thickness of the tread member (mm) is Tc, the thickness of the adhesive layer (mm) is Ta, and the loss tangent of the rubber composition at 70°C is 70°Ctanδ, the value of 70°Ctanδ × (Tc / Ta) is 4.00 or more.

Description

Technical Field

[0001] The present invention relates to retread tires.

Background Art

[0002] In order to realize a sustainable society, in automobiles, further fuel efficiency improvement, vehicle body weight reduction, and the spread of retread technology are required. Generally, retread tires are manufactured by vulcanizing and adhering a casing tire and a tread as described in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] If a retread tire is manufactured by adhering a casing tire and a tread with a resin-based adhesive without vulcanization, large-scale vulcanization equipment is not required, which is convenient. However, since a resin-based adhesive is harder than an adhesive layer made of conventional cushion rubber or the like, there is a concern that the riding comfort performance may deteriorate.

[0005] An object of the present invention is to provide a retread tire in which the deterioration of riding comfort performance is suppressed while using a resin-based adhesive.

Means for Solving the Problems

[0006] The present invention relates to the following retread tire. A retread tire comprising a casing tire, a tread member, and an adhesive layer, wherein the adhesive layer is disposed between the casing tire and the tread member, the tread member is made of a rubber composition, and the adhesive layer is made of a resin-based adhesive. When the thickness (mm) of the tread member is Tc, the thickness (mm) of the adhesive layer is Ta, and the loss tangent of the rubber composition at 70°C is 70°C tanδ, a retread tire in which the value of 70°C tanδ × (Tc / Ta) is 4.00 or more.

Advantages of the Invention

[0007] According to the present invention, it is possible to provide a retread tire in which the deterioration of the riding comfort performance is suppressed while using a resin-based adhesive.

Brief Description of the Drawings

[0008] <## [Figure 1] It is a schematic view showing a part (upper part of the cross-section) of the cross-section of the retread tire according to an embodiment of the present invention by a plane including the tire rotation axis. [Figure 2] It is a cross-sectional view showing an example of a casing tire and a tread member used in the method for manufacturing a retread tire.

Modes for Carrying Out the Invention

[0009] Hereinafter, a retread tire which is an embodiment of the present invention will be described. The retread tire of this embodiment is as follows. A retread tire including a casing tire, a tread member, and an adhesive layer, where the adhesive layer is disposed between the casing tire and the tread member, the tread member is made of a rubber composition, the adhesive layer is made of a resin-based adhesive, When the thickness (mm) of the tread member is Tc, the thickness (mm) of the adhesive layer is Ta, and the loss tangent of the rubber composition at 70°C is 70°C tanδ, a retread tire in which the value of 70°C tanδ × (Tc / Ta) is 4.00 or more.

[0010] While not intended to be constrained by theory, the following mechanisms are considered to suppress the deterioration of ride comfort performance in this embodiment. Specifically, in the retreaded tire of this embodiment, the product of (a) the ratio of the thickness Tc of the tread member to the thickness Ta of the adhesive layer (Tc / Ta) and (b) the loss tangent at 70°C of the rubber composition constituting the tread member (70°C tanδ) is adjusted to be above a certain value. When Tc / Ta is large, it is thought that the deterioration of ride comfort is suppressed because the relatively thick tread member absorbs the impact received from the road surface during driving. On the other hand, when Tc / Ta is small, it is thought that the insufficient thickness of the tread member is compensated for by increasing the 70°C tanδ of the rubber composition constituting the tread member, thereby suppressing the deterioration of ride comfort performance. In other words, it is thought that a large 70°C tanδ of the rubber composition constituting the tread member allows the tread member to convert the energy input from the road surface during driving into thermal energy, thereby suppressing the deterioration of ride comfort. In this embodiment, the retreaded tire, in which the product of Tc / Ta and 70°C tanδ is maintained above a certain value, is thought to be able to suppress a decrease in ride comfort performance even while using a resin-based adhesive.

[0011] The rubber composition preferably contains styrene-butadiene rubber.

[0012] This is because it allows for both low fuel consumption and wear resistance while exhibiting the effects of the present invention.

[0013] The aforementioned rubber composition preferably contains silica.

[0014] This is because it allows for both low fuel consumption and wear resistance while exhibiting the effects of the present invention.

[0015] The average primary particle diameter of the silica is preferably less than 17 nm.

[0016] This is because it allows for both low fuel consumption and wear resistance while exhibiting the effects of the present invention.

[0017] Tc / Ta is preferably greater than 25.0.

[0018] This is because it is advantageous for absorbing impact using the tread material.

[0019] Ta is preferably less than 2.0.

[0020] This is because it is advantageous for absorbing impact using the tread material.

[0021] The value of 70℃ tanδ × (Tc / Ta) is preferably 4.20 or higher, and more preferably 5.00 or higher.

[0022] This is because this embodiment allows the effects of the present invention to be more effectively demonstrated.

[0023] The glass transition temperature of the adhesive layer during curing is preferably above 20°C.

[0024] This is because this embodiment allows the effects of the present invention to be more effectively demonstrated.

[0025] The aforementioned resin-based adhesive is preferably a urethane-based adhesive.

[0026] This is because this embodiment allows the effects of the present invention to be more effectively demonstrated.

[0027] Preferably, the silica content in the rubber composition is 70 parts by mass or less per 100 parts by mass of the rubber component.

[0028] This is because it allows for both low fuel consumption and wear resistance while exhibiting the effects of the present invention.

[0029] <Definition> "Standard condition" refers to a state of no load where the tire is mounted on a standard rim and filled with air at the standard internal pressure. Unless otherwise specified, tires in the standard condition should be used.

[0030] Unless otherwise specified, the "dimensions of each part of the tire" refer to values ​​that are determined in the normal state for those visible on the outer surface of the tire, while those located inside the tire or on the cut surface of the tire refer to values ​​that are determined, for example, by cutting the tire in a plane including the tire's axis of rotation and holding the cut tire piece within the rim width of the normal rim.

[0031] A "standard rim" refers to the rim specified for each tire within the standards system that the tire is based on. For example, for JATMA (Japan Automobile Tire Manufacturers Association), it refers to the standard rim for the applicable size listed in the "JATMA YEAR BOOK," for ETRTO (The European Tyre and Rim Technical Organisation), it refers to the "Measuring Rim" listed in the "STANDARDS MANUAL," and for TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" listed in the "YEAR BOOK." Refer to JATMA, ETRTO, and TRA in that order, and if an applicable size is available at the time of reference, follow that standard. In the case of a tire not specified in the above standards, it refers to the narrowest rim width among the smallest diameter rims that can be mounted on that tire and that can maintain internal pressure (i.e., do not cause air leakage between the rim and tire).

[0032] "Regular internal pressure" refers to the air pressure specified for each tire in the standards system, including the standard on which the tire is based. For example, for JATMA it refers to "maximum air pressure," for ETRTO it refers to "INFLATION PRESSURE," and for TRA it refers to the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." As with regular rims, refer to JATMA, ETRTO, and TRA in that order, and if there is an applicable size at the time of reference, follow that standard. In the case of tires not specified in the above standards, it refers to the regular internal pressure (but at least 250kPa) of another tire size (but specified in the standard) that is listed with the aforementioned regular rim as the standard rim. If multiple regular internal pressures of 250kPa or higher are listed, refer to the lowest value among them.

[0033] "Regular load (kg)" refers to the load specified for each tire in the standard system that the tire is based on. For example, for JATMA it is "Maximum Load Capacity," for ETRTO it is "LOAD CAPACITY," and for TRA it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." As with regular rims and regular in-tire pressure, refer to JATMA, ETRTO, and TRA in that order, and if an applicable size is available at the time of reference, follow that standard. For tires not specified in the above standards, the maximum load capacity (kg) is calculated separately. L This is considered the normal load.

[0034] "Maximum load capacity W L The weight (kg) is calculated using the following formula: "V" is the virtual volume of the tire (mm²). 3), "Dt" is the outer diameter of the tire in the normal state (mm), "Ht" is the height of the tire's cross-section in the radial direction in a plane containing the tire's axis of rotation (mm), and "Wt" is the width of the tire's cross-section in the normal state (mm). Ht can be calculated by (Dt-R) / 2, where R is the rim diameter of the tire. Wt is the value obtained by removing any patterns or letters on the tire's sidewall. Note that the maximum load capacity is synonymous with the normal load mentioned above.

[0035]

number

[0036] A "recycled tire" is the remaining tire portion after the tread has been removed from a tire whose tread has worn down due to use, for the purpose of retreading. By adding new tread material, it can be used as a retreaded tire.

[0037] A "tread component" is the part of a tire that is added to a base tire in order to use it as a retreaded tire.

[0038] "Tread thickness Tc" refers to the thickness (mm) of the tread material measured along the tire centerline in a cross-section of the tire along a plane containing the tire rotation axis. In this embodiment, as shown in Figure 1, Tc is the distance from the tread surface to the radially outer edge of the adhesive layer. Tc is measured with the tire, cut along a plane containing the tire rotation axis, held at the normal rim width. Tc is the average of the thicknesses obtained at five locations by rotating the tire circumferentially by 72° increments.

[0039] The "adhesive layer" is a layer made of resin-based adhesive placed between the tire base and the tread material to bond them together. Here, "resin-based adhesive" refers to both thermoplastic resin-based and thermosetting resin-based adhesives.

[0040] "Adhesive layer thickness Ta" refers to the thickness (mm) of the adhesive layer measured along the tire centerline in a cross-section of the tire along a plane containing the tire's rotation axis. In this embodiment, as shown in Figure 1, Ta is the distance from the radially outer edge to the radially inner edge of the adhesive layer. Ta is measured with the tire, cut along a plane containing the tire's rotation axis, held at the normal rim width. Ta is the average of the thicknesses obtained at five locations by rotating the tire circumferentially by 72° increments.

[0041] <Measurement method> "70°C tanδ of rubber composition" is the loss tangent (tanδ) measured using a dynamic viscoelasticity measuring device (e.g., GABO's Iplexer series) under the conditions of a temperature of 70°C, a frequency of 10Hz, an initial strain of 10%, a dynamic strain of ±1%, and the extension mode. The sample used for measurement is a vulcanized rubber composition measuring 20mm in length, 4mm in width, and 1mm in thickness. When preparing a sample by cutting it from a tire, the length direction of the sample should coincide with the tire's circumferential direction, and the thickness direction of the sample should coincide with the tire's radial direction. If it is difficult to take a sample with a thickness of 1mm, it is acceptable to take a sample as close to 1mm as possible. This is because the elongation at break is measured using a normalized value, and therefore is not affected by thickness.

[0042] The "glass transition temperature" is the static glass transition temperature determined by a differential calorimeter (for example, the Q200 manufactured by T.A. Instruments Japan Co., Ltd.).

[0043] "Styrene content" can be determined by pyrolysis gas chromatography or NMR measurement. 1 H-NMR and 13 It is calculated by 13C-NMR. Unlike physical properties such as the complex modulus (E*), the amounts of components such as "styrene content" have true values ​​that do not depend on the measurement method, so it is preferable to use a measurement method that is as accurate as possible. In this specification, "pyrolysis gas chromatography" refers to a method in which a sample is heated by a pyrolysis apparatus, the individual components contained in the gas phase components produced by this heating are separated by a separation column, and each isolated component is analyzed.

[0044] The "vinyl content (amount of 1,2-bonded butadiene units)" is determined by pyrolysis gas chromatography or NMR measurement ( 1 1H-NMR or 13 13C-NMR). Similar to the "styrene content", since there is a true value that does not depend on the measurement method for the "vinyl content", it is preferable to use a measurement method with as high precision as possible.

[0045] The "cis content (amount of cis-1,4-bonded butadiene units)" is a value measured by infrared absorption spectroscopy or NMR measurement ( 1 1H-NMR or 13 13C-NMR) in accordance with JIS K 6239-2:201, for example, and is applied to rubber components having repeating units derived from butadiene such as BR. Similar to the "styrene content", since there is a true value that does not depend on the measurement method for the "cis content", it is preferable to use a measurement method with as high precision as possible.

[0046] The "weight average molecular weight (Mw)" can be determined by gel permeation chromatography (GPC) (for example, GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKgel (registered trademark) SuperMultiporeHZ-M manufactured by Tosoh Corporation) based on the measured value and converted to standard polystyrene. For example, it is applied to SBR, BR, plasticizers, etc.

[0047] The "nitrogen adsorption specific surface area of carbon black (N2SA)" is measured in accordance with JIS K 6217-2:2017.

[0048] The "nitrogen adsorption specific surface area of silica (N2SA)" is measured by the BET method in accordance with ASTM D3037-93.

[0049] The "average primary particle diameter" is a value obtained by photographing particles with a transmission or scanning electron microscope and calculating the arithmetic mean of the particle diameters of 400 particles. If the particle is spherical, the diameter of the sphere is used as the particle diameter; if it is not spherical, the equivalent diameter of a circle (the positive square root of {4 × (particle area) / π}) is calculated from the microscope image and used as the particle diameter.

[0050] A "plasticizer" is a material that imparts plasticity to rubber components and is extracted from rubber compositions using acetone. Plasticizers include both liquid or liquid plasticizers at 25°C and solid plasticizers at 25°C. However, waxes and stearic acid commonly used in the tire industry are excluded.

[0051] "Plasticizer content" includes the amount of plasticizer in the rubber component that has been stretched by the plasticizer.

[0052] The "softening point of resin components, etc." is, unless otherwise specified, the temperature at which the softening point specified in JIS K 6220-1:2015 is measured using a ring-type softening point measuring device. If the softening point is measured by another method, this will be noted.

[0053] The embodiments will be described in more detail below, but these descriptions are illustrative for the sake of further explanation. Drawings will also be used as appropriate, but these are also illustrative only.

[0054] <Retreaded Tires> Figure 1 is a cross-sectional view of a retreaded tire according to one embodiment. Hereinafter, the retreaded tire may be simply referred to as a tire. The retreaded tire 1 shown in Figure 1 has a base tire 3 having a carcass 4 and a belt 5, positioned radially inward (downward in the figure, hereinafter the same), and a tread member 2 positioned radially outward (upward in the figure, hereinafter the same) of the base tire. An adhesive layer 6 is placed between the tread member 2 and the base tire 3, bonding the tread member 2 and the base tire 3 together. The tread member 2 is made of a rubber composition, and the adhesive layer 6 is made of a resin-based adhesive.

[0055] In tire 1, the thickness of the tread member on the tire centerline CL is indicated by Tc, and the thickness of the adhesive layer on the tire centerline CL is indicated by Ta. The tread member may consist of two layers, a cap tread and a base tread, or it may consist of three or more layers. If the tread member consists of two or more layers, the thickness of the tread member means the total thickness of all those layers.

[0056] (70℃ tanδ × (Tc / Ta)) In the tire of this embodiment, if the thickness of the tread member (mm) is Tc, the thickness of the adhesive layer (mm) is Ta, and the loss tangent of the rubber composition constituting the tread member at 70°C is 70°Ctanδ, then the value of 70°Ctanδ × (Tc / Ta) is 4.00 or greater.

[0057] The value of 70℃ tanδ × (Tc / Ta) is preferably 4.10 or higher, more preferably 4.20 or higher, even more preferably 4.50 or higher, even more preferably 5.00 or higher, even more preferably 5.20 or higher, even more preferably 5.30 or higher, and even more preferably 5.40 or higher. On the other hand, there is no particular upper limit to this value, but it is around 50.00.

[0058] The value of 70°C tanδ × (Tc / Ta) can be adjusted by adjusting the 70°C tanδ of the rubber composition constituting the tread member, the thickness Tc of the tread member, and the thickness Ta of the adhesive layer. Of these, 70°C tanδ can be adjusted by the method described below.

[0059] (Tc / Ta) The Tc / Ta value is preferably greater than 27.0, more preferably greater than 29.0, and even more preferably 30.0 or higher. On the other hand, it is preferable that the value is 300.0 or lower. When the Tc / Ta value is within the above range, it tends to be easier to achieve the effects of the present invention while ensuring adhesion between the tread member and the base tire.

[0060] (Tread material thickness Tc) The thickness Tc of the tread member varies depending on the type of tire. Therefore, it can be of various thicknesses, but in one embodiment, for example, it is preferably 10 mm or more, more preferably 11 mm or more, even more preferably 12 mm or more, even more preferably 13 mm or more, even more preferably 14 mm or more, and even more preferably 15 mm or more. On the other hand, in this embodiment, Tc is preferably 35 mm or less, more preferably 34 mm or less, even more preferably 33 mm or less, even more preferably 32 mm or less, even more preferably 31 mm or less, and even more preferably 30 mm or less.

[0061] (Thickness of the adhesive layer Ta) The thickness Ta of the adhesive layer varies depending on the type of tire. Therefore, it can be of various thicknesses, but in one embodiment, for example, it is preferably 0.1 mm or more, more preferably 0.3 mm or more, and even more preferably 0.5 mm or more. On the other hand, in this embodiment, Ta is preferably 5.0 mm or less, more preferably 4.0 mm or less, even more preferably 3.0 mm or less, even more preferably less than 2.0 mm, and even more preferably less than 1.0 mm.

[0062] (70℃ tanδ) The 70°C tanδ of the rubber composition constituting the tread member is preferably 0.07 or higher, more preferably 0.08 or higher, and even more preferably greater than 0.10. On the other hand, the 70°C tanδ is preferably less than 0.20, more preferably less than 0.19, and even more preferably 0.18 or lower.

[0063] The 70°C tanδ can be increased by increasing the amount of fillers such as silica or carbon black, or plasticizers such as resin components or oils, and conversely, it can be decreased by decreasing the amount of these fillers or plasticizers.

[0064] <Rubber composition constituting the tread material> The rubber composition that makes up the tread material will be described below.

[0065] (Rubber component) The rubber component can be a crosslinkable rubber component commonly used in the tire industry. Examples of such rubber components include diene rubbers such as isoprene rubber (IR rubber), styrene-butadiene rubber (SBR), butadiene rubber (BR), styrene-isoprene-butadiene copolymer rubber (SIBR), styrene-isobutylene-styrene block copolymer (SIBS), chloroprene rubber (CR), and acrylonitrile-butadiene rubber (NBR). The diene rubber component may be used alone or in combination of two or more types.

[0066] Furthermore, the rubber component may include non-diene rubbers such as hydrogenated nitrile rubber (HNBR), butyl rubber (IIR), ethylene propylene rubber, polynorbornene rubber, silicone rubber, polyethylene chloride rubber, fluororubber (FKM), acrylic rubber (ACM), and hydrin rubber. The non-diene rubber component may be used alone or in combination of two or more types.

[0067] Furthermore, the rubber component may or may not contain known thermoplastic elastomers in addition to the rubber component described above.

[0068] In one preferred embodiment, the rubber component comprises isoprene rubber and butadiene rubber, and more preferably consists only of isoprene rubber and butadiene rubber. In another preferred embodiment, the rubber component comprises styrene-butadiene rubber and isoprene rubber and / or butadiene rubber, and more preferably comprises styrene-butadiene rubber, isoprene rubber and butadiene rubber, and even more preferably consists only of styrene-butadiene rubber, isoprene rubber and butadiene rubber.

[0069] Isoprene-based rubber As isoprene-based rubbers, for example, isoprene rubber (IR) and natural rubber, which are common in the tire industry, can be used. Natural rubber includes not only unmodified natural rubber (NR), but also modified natural rubbers such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), and grafted natural rubber. Isoprene-based rubbers may be used alone or in combination of two or more types.

[0070] NR is not particularly limited and can be any that is common in the tire industry, such as SIR20, RSS#3, TSR20, etc.

[0071] The content of isoprene-based rubber in the rubber component is preferably more than 30% by mass, more preferably more than 40% by mass, and even more preferably more than 50% by mass. On the other hand, the content is preferably less than 90% by mass, more preferably less than 80% by mass, and even more preferably less than 70% by mass.

[0072] ≪SBR≫ There are no particular limitations on the SBR; both solution-polymerized SBR (S-SBR) and emulsion-polymerized SBR (E-SBR) can be suitably used, but S-SBR is preferred from the viewpoint of the effects of the present invention. Furthermore, modified SBRs (modified S-SBR, modified E-SBR) can be used as SBRs. Examples of modified SBRs include SBRs in which the terminals and / or main chain are modified, and modified SBRs coupled with tin, silicon compounds, etc. (condensates, those having branched structures, etc.). SBRs may be used alone or in combination of two or more types.

[0073] For SBR, either oil-expanded or non-oil-expanded SBR can be used. As for SBR, commercially available products from JSR Corporation, Sumitomo Chemical Co., Ltd., UBE Corporation, Asahi Kasei Corporation, ZS Elastomer Corporation, ARLANXEO, etc. can be used.

[0074] From the viewpoint of wet grip performance and abrasion resistance, the styrene content of SBR is preferably more than 5% by mass, more preferably more than 7% by mass, and even more preferably 10% by mass or more. Furthermore, from the viewpoint of temperature dependence of grip performance and abrasion resistance, it is preferably less than 40% by mass, more preferably less than 30% by mass, and even more preferably less than 20% by mass. The styrene content of SBR is measured by the measurement method described above.

[0075] From the viewpoint of wet grip performance and abrasion resistance, the vinyl content of SBR is preferably more than 10 mol%, more preferably more than 20 mol%, and even more preferably more than 30 mol%. Furthermore, from the viewpoint of wet grip performance and abrasion resistance, the vinyl content of SBR is preferably less than 60 mol%, more preferably less than 50 mol%, and even more preferably less than 30 mol%. The vinyl content of SBR (amount of 1,2-bonded butadiene units) is measured by the measurement method described above.

[0076] From the viewpoint of wet grip performance, the glass transition temperature (Tg) of SBR is preferably above -80°C, more preferably above -70°C, and even more preferably above -65°C. Furthermore, from the viewpoint of fuel efficiency, the Tg of SBR is preferably below -30°C, more preferably below -35°C, and even more preferably below -40°C. The Tg of SBR is measured by the measurement method described above.

[0077] The weight-average molecular weight (Mw) of SBR is preferably 100,000 or more, more preferably 150,000 or more, and even more preferably 190,000 or more, from the viewpoint of wear resistance. Furthermore, from the viewpoint of crosslinking uniformity, the Mw is preferably 2,500,000 or less, more preferably 2,000,000 or less, and even more preferably 1,000,000 or less. The Mw of SBR is measured by the measurement method described above.

[0078] When SBR is included, its content in the rubber component is preferably more than 5% by mass, more preferably more than 10% by mass, and even more preferably more than 15% by mass, from the viewpoint of abrasion resistance and wet grip performance. Furthermore, from the viewpoint of abrasion resistance, the content is preferably less than 40% by mass, more preferably less than 30% by mass, and even more preferably less than 25% by mass.

[0079] ≪BR≫ BR is not particularly limited, and for example, BR with a cis content of less than 50 mol% (low-cis BR), BR with a cis content of 90 mol% or more (high-cis BR), rare-earth butadiene rubber synthesized using a rare-earth element catalyst (rare-earth BR), BR containing syndiotactic polybutadiene crystals (SPB-containing BR), modified BR (high-cis modified BR, low-cis modified BR), etc., which are common in the tire industry, can be used. BR may be used alone or in combination of two or more types.

[0080] High-cis BR can be commercially available from companies such as Nippon Zeon Co., Ltd., UBE Corporation, and JSR Corporation. Including high-cis BR can improve low-temperature properties and wear resistance. The cis content of high-cis BR is preferably more than 90 mol%, more preferably more than 95 mol%, and even more preferably 96 mol% or more. The cis content of BR is measured by the measurement method described above.

[0081] Rare earth-based BR is synthesized using a rare earth element catalyst, and has a vinyl content of preferably less than 1.8 mol%, more preferably less than 1.5 mol%, and even more preferably less than 1.2 mol%, and a cis content of preferably more than 90 mol%, more preferably more than 95 mol%, and even more preferably 96 mol% or more. As rare earth-based BR, commercially available products from companies such as Lanxess can be used.

[0082] SPB-containing BR refers to a type in which 1,2-syndiotactic polybutadiene crystals are not simply dispersed in BR, but are chemically bonded to and dispersed in BR. Such SPB-containing BR can be commercially available from companies such as UBE Corporation.

[0083] Examples of modified BR include BR modified with functional groups similar to those described for SBR above, as well as modified butadiene rubber (modified BR) in which the terminal and / or main chain is modified with functional groups containing at least one element selected from the group consisting of silicon, nitrogen, and oxygen.

[0084] Other modified BRs include those obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and in which the ends of the modified BR molecule are linked by a tin-carbon bond (tin-modified BR). Furthermore, the modified BR may be either unhydrogenated or hydrogenated.

[0085] From the viewpoint of wear resistance, the weight-average molecular weight (Mw) of BR is preferably greater than 300,000, more preferably greater than 350,000, and even more preferably greater than 400,000. From the viewpoint of crosslinking uniformity, it is preferably less than 2,000,000, more preferably less than 1,000,000, and even more preferably less than 700,000. The Mw of BR can be determined by the method described above.

[0086] The content of BR in the rubber component is not particularly limited, but is preferably more than 5% by mass, more preferably more than 10% by mass, and even more preferably more than 15% by mass. Furthermore, the content of BR in the rubber component is preferably less than 60% by mass, more preferably less than 50% by mass, and even more preferably 40% by mass or less.

[0087] ≪Rubber components synthesized from recycled and biomass-derived raw materials≫ Monomers, which are the constituent units of synthetic rubbers such as IR, SBR, and BR, may be derived from underground resources such as petroleum and natural gas, or they may be recycled from rubber products such as tires or non-rubber products such as polystyrene. The monomers obtained by recycling (recycled monomers) are not particularly limited, but include recycled polyisoprene, recycled butadiene, and recycled aromatic vinyl compounds. Examples of butadiene include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl compounds are not particularly limited, but include styrene. In particular, it is preferable to use recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and / or recycled styrene (recycled styrene) as raw materials.

[0088] The method for producing recycled monomer is not particularly limited, and for example, it can be synthesized from recycled naphtha obtained by decomposing rubber products such as tires. Furthermore, the method for producing recycled naphtha is not particularly limited, and for example, rubber products such as tires may be decomposed under high temperature and pressure, decomposed by microwaves, or extracted after mechanical grinding.

[0089] Furthermore, the monomers that make up polymers such as IR, SBR, and BR may be derived from biomass. In this specification, biomass refers to substances derived from natural resources such as plants. Biomass is not particularly limited, but examples include agricultural, forestry, and fishery products, sugars, wood chips, plant residues after obtaining useful components, plant-derived ethanol, and biomass naphtha.

[0090] The biomass-derived monomer (biomass monomer) is not particularly limited and includes biomass-derived butadiene and biomass-derived aromatic vinyl compounds. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. Examples of the aromatic vinyl compound are not particularly limited but include styrene. Furthermore, the method for producing the biomass monomer is not particularly limited and includes, for example, biological and / or chemical and / or physical transformations of plants and animals. Typical biological transformations include fermentation by microorganisms, while chemical and / or physical transformations include those by catalysts, high heat, high pressure, electromagnetic waves, critical liquids, and combinations thereof.

[0091] The polymer synthesized from biomass monomer components (biomass polymer) is not particularly limited, and examples include polybutadiene rubber synthesized from biomass-derived butadiene, and aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl compounds. Examples of the aromatic vinyl / butadiene copolymer include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0092] Whether the raw materials for a polymer are biomass-derived can be determined by measuring pMC (percent Modern Carbon) according to ASTM D6866-10. pMC refers to the percentage of modern standard reference carbon. 14 Sample relative to C concentration 14 This is a ratio of C concentrations and is used as an indicator of the biomass ratio of a compound. The significance of this value is described below.

[0093] 1 mole of carbon atoms (6.02 × 10⁻¹⁰) 23 (Each) contains approximately 6.02 × 10¹⁶ atoms, which is about one trillionth of the amount of carbon atoms in a normal atom. 11 individual 14 C exists. 14The half-life of C is 5730 years. 14 C is decreasing regularly. Therefore, in fossil fuels such as coal, oil, and natural gas, which are thought to have been fixed after more than 226,000 years have passed since atmospheric carbon dioxide was taken in and fixed by plants, etc., C was initially included in these as well. 14 All elements of C have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas are no longer viable. 14 It contains absolutely no element C. Therefore, chemical substances produced using these fossil fuels as raw materials also contain C. 14 It contains absolutely no element C.

[0094] on the other hand, 14 C is continuously produced when cosmic rays undergo nuclear reactions in the atmosphere. Therefore, 14 In the Earth's atmospheric environment, carbon (C) is produced in a state where its decrease due to radioactive decay and its production through nuclear reactions are in equilibrium. 14 The amount of C is constant. Therefore, the amount of biomass resource-derived substances currently circulating in the environment 14 As mentioned above, the carbon concentration is approximately 1 × 10¹⁶ of the total carbon atoms. -12 These values ​​are approximately in mole percent. Therefore, the difference between these values ​​can be used to calculate the biomass ratio in a given compound.

[0095] this 14 C is typically measured as follows: Using accelerator mass spectrometry based on a tandem accelerator, 13 C concentration ( 13 C / 12 C), 14 C concentration ( 14 C / 12 Perform measurement C). In the measurement, 14 As a modern standard reference for the concentration of C, the amount of cyclic carbon in nature as of 1950 14The C concentration will be used. The specific standard material will be the oxalic acid standard provided by NIST (National Institute of Standards and Technology). The specific radioactivity of carbon in this oxalic acid (per gram of carbon) will be used. 14 The radioactivity intensity of C is separated by carbon isotope, 13 The standard value is obtained by correcting C to a constant value and applying decay correction from 1950 AD to the measurement date. 14 This value is used as the C concentration value (100%). The ratio of this value to the value of the sample actually measured is the pMC value.

[0096] Therefore, if rubber is made from 100% biomass-derived materials, although there are regional differences, under normal conditions it will often not reach 100, and will show a value of approximately 110 pMC. On the other hand, regarding chemical substances derived from fossil fuels such as petroleum, 14 When the C concentration is measured, it will show a value of approximately 0 pMC (for example, 0.3 pMC). This value corresponds to the aforementioned biomass ratio of 0%.

[0097] Based on the above, using materials such as rubber with a high pMC value, that is, materials such as rubber with a high biomass ratio, in rubber compositions is preferable from an environmental protection standpoint.

[0098] (Filler) The filler can be any filler commonly used in the tire industry. Preferably, the filler contains silica and / or carbon black. The filler may contain fillers other than silica and carbon black, but it may also consist solely of carbon black, or solely of carbon black and silica. Furthermore, the filler may contain recycled carbon black.

[0099] Other fillers besides silica and carbon black are not particularly limited, but may include, for example, aluminum hydroxide, calcium carbonate, alumina, clay, talc, and other materials commonly used in the tire industry.

[0100] The filler may be used alone or in combination of two or more types.

[0101] Silica The silica used is not particularly limited, and common silica used in the tire industry can be used, such as silica prepared by a dry process (anhydrous silica) or silica prepared by a wet process (hydrated silica). The raw material for silica is not particularly limited, and may be a mineral-derived raw material such as quartz, or a biological-derived raw material such as rice husks (for example, silica made from biomass materials such as rice husks), or silica recycled from silica-containing products may be used. Among these, hydrated silica prepared by a wet process is preferred because it contains a large number of silanol groups. Silica may be used alone or in combination of two or more types.

[0102] Silica derived from biomass materials can be obtained, for example, by extracting silicates from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and then using these silicates to react with sulfuric acid in the same way as conventional wet silica, the precipitate of silicon dioxide is filtered, washed with water, dried, and pulverized.

[0103] The silica recycled from silica-containing products can be, for example, silica recovered from products containing silica such as semiconductors and other electronic components, tires, desiccants, and diatomaceous earth and other filter materials. The recovery method is not particularly limited and can include thermal decomposition and decomposition by electromagnetic waves. Among these, silica recovered from semiconductors and other electronic components or tires is preferred.

[0104] When silica crystallizes, it becomes insoluble in water, and its component, silicic acid, cannot be utilized. By controlling the combustion temperature and combustion time, the crystallization of silica in rice husk ash can be suppressed (see Japanese Patent Publication No. 2009-2594, Akita Prefectural University Web Journal B / 2019, vol.6, pp.216-222, etc.). Amorphous silica extracted from rice husks can be commercially available from companies such as Wilmar.

[0105] The nitrogen adsorption specific surface area (N2SA) of silica is 170 m², from the viewpoint of wear resistance and fracture characteristics. 2 Preferably more than / g, 190m 2 More preferably than / g, 210m 2 More preferably than / g, 230m 2 More preferably than / g, 235m 2 A value of 500m or more is even more preferable. Furthermore, N2SA is preferable from the viewpoint of processability. 2 Preferably less than / g, 350m 2 Less than / g is more preferable, 300m 2 It is even more preferable that the amount be less than / g, and 250m 2 A value less than / g is even more preferable. The N2SA of silica is the value measured by the measurement method described above.

[0106] From the viewpoint of the effects of the present invention, the average primary particle diameter of silica is preferably less than 18 nm, more preferably less than 17 nm, even more preferably less than 16 nm, and even more preferably 15 nm or less. Furthermore, from the viewpoint of processability, the average primary particle diameter is preferably greater than 12 nm, more preferably greater than 13 nm, and even more preferably greater than 14 nm. The average primary particle diameter of silica is measured by the measurement method described above.

[0107] From the viewpoint of balancing fuel efficiency and wet grip performance, the silica content is preferably more than 20 parts by mass, more preferably more than 25 parts by mass, and even more preferably 30 parts by mass or more, per 100 parts by mass of rubber component. Furthermore, from the viewpoint of processability, the silica content is preferably less than 150 parts by mass, more preferably less than 100 parts by mass, even more preferably less than 80 parts by mass, even more preferably 70 parts by mass or less, even more preferably less than 60 parts by mass, and even more preferably 55 parts by mass or less.

[0108] ≪Silane coupling agents≫ Silica is preferably used in combination with a silane coupling agent. The silane coupling agent is not particularly limited, but examples include: sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl) disulfide and bis(3-triethoxysilylpropyl) tetrasulfide; mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, and 2-mercaptoethyltriethoxysilane; vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; and 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane. Examples of silane coupling agents include amino-based silane coupling agents such as 3-(2-aminoethyl)aminopropyltriethoxysilane; glycidoxy-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Among these, it is preferable to contain a sulfide-based silane coupling agent and / or a mercapto-based silane coupling agent. As silane coupling agents, for example, those commercially available from Evonik Industries, Momentive, etc., can be used. Silane coupling agents may be used alone or in combination of two or more.

[0109] From the viewpoint of improving silica dispersibility, the content of the silane coupling agent per 100 parts by mass of silica is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and even more preferably 8 parts by mass or more. Furthermore, from the viewpoint of cost and processability, it is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, and even more preferably 16 parts by mass or less.

[0110] Carbon Black The carbon black used is not particularly limited and includes N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. The raw materials for carbon black may be biomass materials such as lignin and vegetable oil, or pyrolysis oil obtained by thermal decomposition of waste tires. The manufacturing method for carbon black may be combustion such as the furnace method, hydrothermal carbonization (HTC), or thermal decomposition of methane such as the thermal black method. Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., and Columbia Carbon Corporation. Carbon black may be used alone or in combination of two or more types.

[0111] In addition to the above, recycled carbon black, obtained by thermally decomposing and refining products containing carbon black, such as tires, may also be used as carbon black, from the perspective of life cycle assessment.

[0112] Recycled carbon black can be obtained from the pyrolysis process of used pneumatic tires. For example, European Patent Application Publication No. 3427975, which refers to "Rubber Chemistry and Technology," Vol. 85, No. 3, pp. 408-449 (2012), particularly pp. 438, 440, and 442, states that it can be obtained by the pyrolysis of organic materials at 550-800°C in the absence of oxygen, or by vacuum pyrolysis at relatively low temperatures (

[0027] ). Carbon black obtained from such pyrolysis processes usually lacks functional groups on its surface, as referred to in

[0004] of Japanese Patent Publication No. 6856781 (Comparison of Surface Morphology and Chemistry of Pyrolysis Carbon Black and Commercial Carbon Black, Powder Technology 160 (2005) 190-193).

[0113] Recycled carbon black may lack functional groups on its surface, or it may be treated to include functional groups on its surface. Treatment to include functional groups on the surface of recycled carbon black can be carried out by conventional methods. For example, in European Patent Application Publication No. 3173251, carbon black obtained from a pyrolysis process is treated with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl and / or carboxyl groups on its surface. In addition, in Japanese Patent Publication No. 6856781, carbon black obtained from a pyrolysis process is treated with an amino acid compound containing at least one thiol group or disulfide group to obtain carbon black with an activated surface. The recycled carbon black according to this embodiment also includes carbon black treated to include functional groups on its surface.

[0114] Recycled carbon black can be purchased from companies such as Strable Green Carbon and LD Carbon.

[0115] The nitrogen adsorption specific surface area (N2SA) of carbon black is 80m², considering its weather resistance and reinforcing properties. 2 Preferably more than / g, 100m2 More preferably than / g, 120m 2 A value exceeding / g is even more preferable. Furthermore, N2SA is preferable in terms of dispersibility, low fuel consumption performance, fracture characteristics and durability, at 250m 2 Preferably less than / g, 220m 2 Less than / g is more preferable, 180m 2 It is even more preferable that the amount be less than / g, and 150m 2 A value of less than / g is even more preferable. The N2SA of carbon black is measured by the measurement method described above.

[0116] The average primary particle size of carbon black is preferably greater than 12 nm, more preferably greater than 15 nm, and even more preferably greater than 17 nm, from the viewpoint of weather resistance and reinforcing properties. Furthermore, from the viewpoint of dispersibility, low fuel consumption performance, fracture characteristics, and durability, the average primary particle size is preferably less than 25 nm, more preferably less than 22 nm, and even more preferably less than 20 nm. The average primary particle size of carbon black is measured by the measurement method described above.

[0117] From the viewpoint of weather resistance and reinforcing properties, the carbon black content per 100 parts by mass of rubber component is preferably more than 1 part by mass, more preferably more than 3 parts by mass, and even more preferably 5 parts by mass or more. Furthermore, from the viewpoint of low fuel consumption performance, the content is preferably less than 80 parts by mass, more preferably less than 70 parts by mass, and even more preferably less than 60 parts by mass. This content includes the content of recycled carbon black.

[0118] From the viewpoint of wear resistance, the total content of silica and carbon black per 100 parts by mass of rubber component is preferably more than 20 parts by mass, more preferably more than 25 parts by mass, and even more preferably 30 parts by mass or more. Furthermore, from the viewpoint of suppressing a decrease in fuel efficiency and wear resistance, it is preferably less than 180 parts by mass, more preferably less than 130 parts by mass, and even more preferably less than 110 parts by mass.

[0119] (Other combination drugs) In addition to the above-mentioned components, the rubber composition may appropriately contain compounding agents commonly used in the tire industry, such as plasticizers, vulcanized rubber particles (rubber powder), antioxidants, waxes, processing aids, stearic acid, zinc oxide, vulcanizing agents, and vulcanization accelerators.

[0120] Plasticizers Examples of plasticizers include resin components, oils, liquid rubber, and ester-based plasticizers. These plasticizers may be derived from mineral resources such as petroleum and natural gas, from biomass, or from naphtha recycled from rubber or non-rubber products. In addition, low molecular weight hydrocarbon components obtained by thermal decomposition and extraction of used tires or products containing various components may be used as plasticizers. Plasticizers may be used individually or in combination of two or more types.

[0121] • Resin components The rubber composition according to this embodiment may also contain a resin component. The resin component that can be used in this embodiment is not particularly limited, but resins commonly used in the tire industry can be used, such as C9 resins, C5 resins, C5C9 resins, dicyclopentadiene resins, aromatic vinyl resins, coumarone resins, indene resins, terpene resins, rosin resins, phenolic resins, etc. These resin components may be used individually or in combination of two or more. Each resin component may also be used individually or in combination of two or more.

[0122] C9 resin A "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, and may be a polymer obtained by polymerizing the C9 fraction alone, or a copolymer obtained by copolymerizing the C9 fraction with other components. For example, a resin obtained by copolymerizing dicyclopentadiene (DCPD) and a C9 fraction is called a DCPD / C9 resin. Furthermore, the C9 resin may be a hydrogenated or modified version of these resins. Examples of C9 fractions include petroleum fractions with 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, coumarone, indene, methylindene, and dicyclopentadiene. As for C9 resins, commercially available products from companies such as BASF, Zeon Corporation, and ENEOS Corporation can be used.

[0123] C5 resin "C5 resins" refer to resins obtained by polymerizing C5 fractions, and may be hydrogenated or modified resins. Examples of C5 fractions other than dicyclopentadiene include petroleum fractions with 4 to 5 carbon atoms, such as cyclopentadiene, isoprene, piperylene, 2-methyl-1-butene, 2-methyl-2-butene, and 1-pentene. As C5 resins, commercially available products from companies such as Structol, Nippon Zeon Co., Ltd., and ENEOS Corporation can be used.

[0124] C5C9 resin "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be hydrogenated or modified. As C5C9 petroleum resin, commercially available products from companies such as Tosoh Corporation and LUHUA can be used.

[0125] Dicyclopentadiene resin A "dicyclopentadiene-based resin" refers to a resin in which cyclopentadiene (CPD) and / or dicyclopentadiene (DCPD) are the most abundant monomer components, and these may be hydrogenated or modified resins. Preferred dicyclopentadiene-based resins include polymers obtained by polymerizing only dicyclopentadiene as a monomer, and copolymers (DCPD / C9 resins) obtained by copolymerizing dicyclopentadiene with the C9 fraction. Commercially available dicyclopentadiene-based resins from companies such as ExxonMobil, ENEOS Corporation, Nippon Zeon Corporation, and Maruzen Petrochemical Co., Ltd. can be used.

[0126] Aromatic vinyl resin "Aromatic vinyl resin" refers to a resin in which aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, and p-chlorostyrene are the most abundant monomer components, and these may be hydrogenated or modified. As aromatic vinyl resins, α-methylstyrene or a homopolymer of styrene or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred, for reasons of being economical, easy to process, and having excellent heat generation properties. As aromatic vinyl resins, commercially available products from companies such as Kraton, Eastman Chemical Company, and Mitsui Chemicals, Inc. can be used.

[0127] Coumaron resin "Coumarone-based resin" refers to a resin containing coumarone as a monomer component, and may be hydrogenated or modified. Preferred coumarone-based resins include, for example, coumarone resin, which is a polymer with coumarone as the monomer component; coumarone-indene resin, which is a copolymer with coumarone and indene as monomer components; and coumarone-indene-styrene resin, which is a copolymer with coumarone, indene, and styrene as monomer components. As coumarone-based resins, commercially available products from companies such as Rutgers, Nippon Paint Chemical Co., Ltd., and Mitsui Chemicals, Inc. can be used.

[0128] Indene resin "Indene-based resin" refers to a resin containing indene as a monomer component, and may be hydrogenated or modified resins. Preferred indene-based resins include, for example, coumarone-indene resin, which is a copolymer of coumarone and indene as monomer components, and coumarone-indene-styrene resin, which is a copolymer of coumarone, indene, and styrene as monomer components. Commercially available indene-based resins from companies such as Rutgers, Nippon Paint Chemical Co., Ltd., and Mitsui Chemicals, Inc. can be used.

[0129] Terpene resins "Terpene resin" refers to a resin containing terpene compounds such as α-pinene, β-pinene, limonene, and dipentene as monomer components, and may be hydrogenated or modified. Preferred terpene resins include, for example, polyterpene resins, which are polymers in which one or more of the aforementioned terpene compounds are used as monomer components; aromatically modified terpene resins, which are copolymers in which the aforementioned terpene compounds and aromatic compounds are used as monomer components; and terpene phenol resins, which are copolymers in which the aforementioned terpene compounds and phenol compounds are used as monomer components. Examples of aromatic compounds that serve as monomer components in aromatically modified terpene resins include styrene, α-methylstyrene, vinyltoluene, and divinyltoluene. Examples of phenol compounds that serve as monomer components in terpene phenol resins include phenol, bisphenol A, cresol, and xylenol. As terpene resins, commercially available products from companies such as Yasuhara Chemical Co., Ltd., Arakawa Chemical Industries, Ltd., and Nippon Terpene Chemical Co., Ltd. can be used.

[0130] Rosin-based resin "Rosin-based resin" refers to a resin containing rosin acid compounds such as abietic acid, neoabietic acid, palastic acid, and isopimal acid, and may be hydrogenated or modified. Rosin-based resins are not particularly limited, but examples include natural resin rosin and rosin-modified resins obtained by hydrogenating, disproportionating, dimerizing, esterifying, etc. As rosin-based resins, commercially available products from companies such as Harima Chemical Industries, Ltd., Arakawa Chemical Industries, Ltd., and IREC Co., Ltd. can be used.

[0131] Phenolic resins "Phenol-based resins" refer to resins containing phenol compounds such as phenol and cresol as monomer components, and may also be hydrogenated or modified resins. Phenolic resins are not particularly limited, but examples include phenol-formaldehyde resins, alkylphenol-formaldehyde resins, alkylphenol-acetylene resins, oil-modified phenol-formaldehyde resins, and terpene-phenol resins. Phenolic resins that are commercially available from companies such as Sumitomo Bakelite Co., Ltd., DIC Corporation, and Asahi Organic Materials Co., Ltd. can be used.

[0132] From the viewpoint of wet grip performance, the softening point of the resin is preferably above 80°C, more preferably above 90°C, and even more preferably above 100°C. Furthermore, from the viewpoint of processability and improved dispersibility between the rubber component and filler, it is preferably below 150°C, more preferably below 140°C, and even more preferably below 130°C. The softening point of the resin is measured by the measurement method described above.

[0133] The resin content per 100 parts by mass of rubber component is preferably more than 1 part by mass, more preferably more than 5 parts by mass, and even more preferably 5 parts by mass or more. On the other hand, from the viewpoint of suppressing heat generation, the content is preferably less than 60 parts by mass, more preferably less than 30 parts by mass, and even more preferably less than 20 parts by mass.

[0134] ·oil Examples of oils include mineral oil, vegetable oil, and animal oil. Furthermore, from a life cycle assessment perspective, waste oil from rubber mixers and engines, or refined waste cooking oil from restaurants, may also be used. Oils may be used individually or in combination of two or more types.

[0135] Mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. Examples of mineral oil include paraffinic oils (mineral oil), naphthenic oils, and aromatic oils. Specific examples of mineral oils include MES (Mild Extracted Solvate), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), and RAE (Residual Aromatic Extract). Furthermore, for environmental reasons, oils with a low content of polycyclic aromatic compounds (PCA) can be used. Examples of low-PCA oils include MES, TDAE, and heavy naphthenic oils.

[0136] Examples of vegetable oils include linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice bran oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grapeseed oil, and wood wax. Furthermore, vegetable oils can also include refined oils (such as salad oil) obtained by refining the above oils, transesterified oils obtained by transesterifying the above oils, hydrogenated oils obtained by hydrogenating the above oils, thermally polymerized oils obtained by thermally polymerizing the above oils, oxidized polymerized oils obtained by oxidizing the above oils, and waste cooking oils recovered from use as edible oils. Note that vegetable oils may be liquid or solid at 25°C.

[0137] The vegetable oil preferably contains acylglycerol, and more preferably contains triacylglycerol. In this specification, acylglycerol refers to a compound in which a hydroxyl group of glycerin is esterified with a fatty acid. The acylglycerol is not particularly limited and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Furthermore, the acylglycerol may be a monomer, a dimer, or a polymer of three or more. Acylglycerols of two or more mers can be obtained by thermal polymerization, oxidative polymerization, etc. Also, the acylglycerol may be a liquid or a solid at 25°C.

[0138] The method for confirming whether the rubber composition contains the acylglycerol is not particularly limited, 1 This can be confirmed by 1H-NMR measurement. For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at 25°C for 24 hours, and after removing the rubber composition, it is measured at room temperature. 1 When 1H-NMR was measured and the tetramethylsilane (TMS) signal was set to 0.00 ppm, signals were observed around 5.26 ppm, 4.28 ppm, and 4.15 ppm. These signals are presumed to originate from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. In this paragraph, "around" refers to a range of ±0.10 ppm.

[0139] The aforementioned fatty acids are not particularly limited and may be unsaturated or saturated fatty acids. Examples of unsaturated fatty acids include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of saturated fatty acids include butyric acid and lauric acid.

[0140] In particular, it is desirable that the fatty acid contains fatty acids with few double bonds, i.e., saturated fatty acids or monounsaturated fatty acids, and oleic acid is preferred. As a vegetable oil containing such fatty acids, for example, a vegetable oil containing saturated fatty acids or monounsaturated fatty acids may be used, or a vegetable oil that has been modified by transesterification or other means may be used. Furthermore, in order to produce a vegetable oil containing such fatty acids, plants may be improved by breeding, genetic modification, genome editing, etc.

[0141] As for vegetable oils, commercially available products from companies such as Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kosan Co., Ltd., and Nisshin Oillio Group Ltd. can be used.

[0142] Examples of animal oils include fish oil, beef tallow, or oleyl alcohol derived from them.

[0143] When oil is included, the oil content per 100 parts by mass of rubber component is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, from the viewpoint of processability. Furthermore, from the viewpoint of wear resistance, it is preferably 120 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 30 parts by mass or less. The oil content also includes the amount of oil contained in the oil-spread rubber.

[0144] Liquid rubber The liquid rubber is not particularly limited as long as it is a polymer that is in a liquid state at 25°C, but examples include liquid butadiene rubber (liquid BR), liquid styrene butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene isoprene rubber (liquid SIR), liquid farnesene rubber, etc. The liquid rubber may be used alone or in combination of two or more types.

[0145] When liquid rubber is included, its content per 100 parts by mass of rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more. Furthermore, the liquid rubber content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 10 parts by mass or less. The liquid rubber content also includes the amount of stretchable liquid rubber used to stretch the rubber component.

[0146] • Ester-based plasticizers Examples of ester-based plasticizers include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di-2-ethylhexyl azelaate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), and trixylenyl phosphate (TXP). Ester-based plasticizers may be used individually or in combination of two or more.

[0147] When an ester-based plasticizer is included, its content per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more. The liquid rubber content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 10 parts by mass or less. The ester-based plasticizer content also includes the amount of stretched ester-based plasticizer used to stretch the rubber component.

[0148] Vulcanized rubber particles Vulcanized rubber particles are particles made of vulcanized rubber, and specifically, rubber powder as specified in JIS K 6316:2017 can be used. From the viewpoint of environmental considerations and cost, recycled rubber powder produced from crushed waste tires is preferred. One type of vulcanized rubber particle may be used alone, or two or more types may be used in combination.

[0149] The vulcanized rubber particles are not particularly limited and may be either unmodified or modified vulcanized rubber particles. Commercially available vulcanized rubber products can be used, for example, those from Lehigh, Muraoka Rubber Industries, and others.

[0150] When vulcanized rubber particles are included, the content per 100 parts by mass of the rubber component can be appropriately adjusted, for example, within a range of more than 1 part by mass and less than 80 parts by mass.

[0151] Anti-aging agent While not particularly limited, examples of anti-aging agents include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), and N,N'-ditril-p-phenylenediamine. Examples include p-phenylenediamine-based antioxidants such as methyl amine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, and polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. Commercially available products include those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., Flexis, and others. The antioxidant may be used alone or in combination of two or more.

[0152] When an anti-aging agent is included, the content per 100 parts by mass of rubber component is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, from the viewpoint of the rubber's resistance to ozone cracking. Furthermore, from the viewpoint of wear resistance and wet grip performance, it is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less.

[0153] ≪Wax≫ The wax is not particularly limited, and any wax commonly used in the tire industry can be suitably used, such as mineral waxes and plant-derived waxes. Mineral waxes refer to waxes derived from mineral resources such as oil and natural gas. Plant-derived waxes refer to waxes derived from natural resources such as plants. Among these, mineral waxes are preferred. Examples of plant-derived waxes include rice wax, carnauba wax, and candelilla wax. Examples of mineral waxes include paraffin wax, microcrystalline wax, and selected special waxes thereof, with paraffin wax being preferred. The wax according to this embodiment does not contain stearic acid. The wax can be commercially available from companies such as Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Paramelt Co., Ltd. The wax may be used alone or in combination of two or more types.

[0154] When wax is included, the amount of wax per 100 parts by mass of rubber component is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, from the viewpoint of weather resistance of the rubber. Furthermore, from the viewpoint of preventing whitening of the tire due to bloom, it is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less.

[0155] Processing aids Examples of processing aids include fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, fatty acid esters, mixtures of fatty acid metal salts and amide esters, and mixtures of fatty acid metal salts and fatty acid amides. For example, commercially available processing aids from companies such as Schill+Seilacher and Performance Additives can be used. Processing aids may be used individually or in combination of two or more.

[0156] When processing aids are included, the content per 100 parts by mass of rubber components is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, from the viewpoint of exhibiting an effect of improving processability. Furthermore, from the viewpoint of wear resistance and fracture strength, it is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 5 parts by mass or less.

[0157] ≪Stearic Acid≫ When stearic acid is included, its content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, from the viewpoint of processability. Furthermore, from the viewpoint of vulcanization rate, it is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less.

[0158] ≪Zinc Oxide≫ When zinc oxide is included, its content per 100 parts by mass of rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, from the viewpoint of processability. Furthermore, from the viewpoint of wear resistance, it is preferably 5.0 parts by mass or less, more preferably 4.5 parts by mass or less, and even more preferably 4.0 parts by mass or less.

[0159] ≪Sulfurizing agent≫ Sulfur is preferably used as a vulcanizing agent. Suitable sulfurs include powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur. The vulcanizing agent may be used alone or in combination of two or more types.

[0160] When sulfur is included as a vulcanizing agent, the amount of sulfur per 100 parts by mass of rubber component is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, from the viewpoint of ensuring a sufficient vulcanization reaction. Furthermore, from the viewpoint of preventing deterioration, it is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, and even more preferably 3.0 parts by mass or less. When oil-containing sulfur is used as the vulcanizing agent, the amount of vulcanizing agent is the total amount of pure sulfur contained in the oil-containing sulfur.

[0161] Examples of vulcanizing agents other than sulfur include alkylphenol-sulfur chloride condensates, 1,6-hexamethylene-dithiosulfate sodium dihydrate, and 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane. These non-sulfur vulcanizing agents can be commercially available from companies such as Taoka Chemical Industries, Ltd., Lanxess Corporation, and Flexis. The vulcanizing agents may be used individually or in combination of two or more.

[0162] <<Vulcanization accelerator>> Examples of vulcanization accelerators include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamate, aldehyde-amine or aldehyde-ammonia, imidazoline, or xanthate vulcanization accelerators. Among these, sulfenamide, thiazole, and guanidine vulcanization accelerators are preferred. The vulcanization accelerator may be used alone or in combination of two or more types.

[0163] Examples of sulfenamide-based vulcanization accelerators include N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS), N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS), and N,N-dicyclohexyl-2-benzothiazolyl sulfenamide (DCBS). Among these, N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS) is preferred.

[0164] Examples of thiazole-based vulcanization accelerators include 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, and di-2-benzothiazolyl disulfide. Among these, 2-mercaptobenzothiazole is preferred.

[0165] Examples of guanidine-based vulcanization accelerators include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salts of dicatecholborate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, and 1,3-di-o-cumenyl-2-propionylguanidine. Among these, 1,3-diphenylguanidine (DPG) is preferred.

[0166] When a vulcanization accelerator is included, its content per 100 parts by mass of the rubber component is preferably 1 part by mass or more, and more preferably 1.5 parts by mass or more. Furthermore, the content of the vulcanization accelerator per 100 parts by mass of the rubber component is preferably 8 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 6 parts by mass or less. By keeping the content of the vulcanization accelerator within the above range, it tends to be possible to ensure fracture strength and elongation.

[0167] (Various materials containing carbon atoms) In this specification, various materials containing carbon atoms (e.g., rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from atmospheric carbon dioxide. Methods for obtaining these materials from carbon dioxide include directly converting carbon dioxide, or converting methane obtained through a methanation process in which methane is synthesized from carbon dioxide.

[0168] <Adhesive layer> The adhesive layer is a layer made of a resin-based adhesive. Generally, adhesives are classified into inorganic adhesives and organic adhesives, and among organic adhesives, natural and synthetic (thermoplastic resin, thermosetting resin, elastomer, etc.) adhesives are known. The resin-based adhesive in this embodiment corresponds to thermoplastic resin and thermosetting resin adhesives.

[0169] Regarding adhesives, thermoplastic resins include vinyl acetate resins, polyvinyl acetal resins, ethylene vinyl acetate resins, vinyl chloride resins, acrylic resins (such as butyl acrylate and other acrylic acid esters), polyamides, cellulose, and α-olefins. Thermosetting resins include urethane resins, urea resins, melamine resins, phenolic resins, resorcinol resins, epoxy resins, structural acrylic resins, polyesters, and polyaromatics. Commercially available resin adhesives can be used. Resin adhesives can be used individually or in combination of two or more types.

[0170] The glass transition temperature (Tg) of the resin-based adhesive during curing is preferably above 20°C, more preferably above 30°C, even more preferably above 40°C, and even more preferably above 50°C. Furthermore, the Tg is preferably below 150°C, more preferably below 120°C, even more preferably below 100°C, and even more preferably below 80°C.

[0171] As for resin-based adhesives, urethane resin-based adhesives are preferred.

[0172] <Manufacturing Method> Retreaded tires can be manufactured by known methods.

[0173] The rubber composition constituting the tread material can be manufactured by known methods. For example, it can be manufactured by kneading each of the above components using a rubber kneading device such as an open roll or a closed-type kneader (Banbury mixer, kneader, etc.). The kneading process includes, for example, a base kneading process in which compounding agents and additives other than the vulcanizing agent and vulcanization accelerator are kneaded, and a final kneading (F kneading) process in which the vulcanizing agent and vulcanization accelerator are added to the mixture obtained in the base kneading process and kneaded. Furthermore, the base kneading process can be divided into multiple processes as desired. The kneading conditions are not particularly limited, but for example, in the base kneading process, kneading is performed at a discharge temperature of 150 to 170°C for 3 to 10 minutes, and in the final kneading process, kneading is performed at 70 to 110°C for 1 to 5 minutes.

[0174] The tread member can be manufactured using the rubber composition by a conventional method. Specifically, the unvulcanized rubber composition can be extruded into the shape of the tread member using an extruder equipped with a die of a predetermined shape, and then heated and pressurized in a vulcanizing machine. The vulcanization conditions are not particularly limited, but for example, a method of vulcanization at 140 to 170°C for 10 to 40 minutes can be used. It is preferable to pre-buff the joint surface of the tread member with the base tire.

[0175] On the other hand, a base tire can be manufactured by removing the tread portion from a tire whose tread has worn down through use, or by forming an unvulcanized base tire by bonding the unvulcanized tire components that make up the base tire on a tire molding machine to form a predetermined base tire structure and molding it in a conventional manner, and then heating and pressurizing this unvulcanized base tire in a vulcanizing machine. The vulcanization conditions are not particularly limited, but for example, a method of vulcanizing at 140 to 170°C for 10 to 40 minutes can be used. It is preferable to pre-buff the bonding surface of the base tire with the tread component.

[0176] An adhesive layer made of a resin-based adhesive is placed between the tread member and the base tire. Methods for placing the adhesive layer include placing an adhesive sheet, formed by creating a film of adhesive, between the base tire and the tread member, or applying adhesive to at least one surface of the base tire and the tread member before mounting the tread member to the base tire. From the viewpoint of simplifying the adhesive layer placement process, the method using an adhesive sheet is preferred. Furthermore, when the adhesive layer is to be thin, it is preferable to apply the adhesive to at least one surface of the base tire and the tread member.

[0177] Adhesive sheets can be suitably manufactured by applying an adhesive to a release sheet such as release paper or release film and maintaining the sheet shape. Alternatively, adhesive sheets can be manufactured by applying an adhesive to the surface of the components to be bonded and holding them in place. This holding can be done by leaving the adhesive at room temperature, but it can also be done by promoting a partial urethane reaction by applying at least one of heating and / or light irradiation to an extent that does not initiate a radical reaction. Visible light irradiation may be used for the light irradiation, but ultraviolet irradiation may also be used.

[0178] There are no particular restrictions on the material of the release sheet, but polyester resins such as polyethylene terephthalate, polycyclohexylene terephthalate, and polyethylene naphthalate; polyamide resins such as nylon 46, modified nylon 6T, nylon MXD6, and polyphthalamide; ketone resins such as polyphenylene sulfide and polythioethersulfone; and sulfone resins such as polysulfone and polyethersulfone, as well as transparent resin substrates mainly composed of organic resins such as polyethernitrile, polyarylate, polyetherimide, polyamideimide, polycarbonate, polymethyl methacrylate, triacetylcellulose, polystyrene, and polyvinyl chloride can be suitably used. The thickness of the adhesive sheet (excluding the release sheet) is preferably, for example, 0.1 mm to 3 mm.

[0179] Various methods can be used to apply resin-based adhesives, such as manual or machine application methods including brush application, roller brush application, tampon application, and spatula application; inkjet printing; spray coating methods including spray application, hot spray application, airless spray application, and hot airless spray application; curtain flow application; flow application; roll coating; gravure coating; dipping; rolling application; spin coating; reverse coating; bar coating; screen coating; blade coating; air knife coating; dispensing with a dispenser; T-die molding; and thin-film extrusion molding. When applying adhesive to a release sheet or the like to form an adhesive sheet, the application method can also be the one described above.

[0180] A tire in which an adhesive layer made of resin-based adhesive is placed between the tread member and the base tire can be made into a retreaded tire by leaving it as is to allow the adhesive layer to harden.

[0181] <Application> The retreaded tires according to this embodiment can be used for various applications, and are suitably used, for example, as retreaded tires for aircraft, linear motor cars, or trucks and buses. [Examples]

[0182] The following examples (case studies) are shown as preferred for implementation, but the scope of the present invention is not limited to these examples. Tread members and base tires composed of rubber compositions obtained using the various chemicals shown below were examined according to each table, and the results calculated based on the evaluation method below are shown.

[0183] [Various medicines] The various materials used in the examples and comparative examples are summarized below. IR-type rubber: NR (TSR20) SBR: SL553R manufactured by JSR Corporation (styrene content: 10% by mass, vinyl content: 37 mol%, Tg: -60℃) BR: BR730 manufactured by JSR Corporation (BR synthesized using an Nd-based catalyst, cis content: 96.6 mol%, Mw: 580,000) CB (Carbon Black): Show Black N134 (N2SA: 148ml) manufactured by Cabot Japan Co., Ltd. 2 / g, average primary particle diameter: 18nm) Silica: ULTRASIL(registered trademark) 9100GR (N2SA235m) manufactured by Evonik Industries. 2 / g, average primary particle diameter: 15nm) Coupling agent (silane coupling agent): Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Industries. Oil: Diana Process NH-70S manufactured by Idemitsu Kosan Co., Ltd. Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Anti-aging agent: Nocrack 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Stearic acid: Beads of stearic acid manufactured by NOF Corporation Wax: Ozoace 0355 (paraffin wax) manufactured by Nippon Seiro Co., Ltd. Sulfur: 5% oil-treated powdered sulfur manufactured by Tsurumi Chemical Industries Co., Ltd. Vulcanization accelerator: Noxellar NS-P (N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Resin-based adhesive: BetaFuse manufactured by DuPont

[0184] [Examples and Comparative Examples] <Tread material> Tread components are manufactured according to the tire structure and compound formulation shown in each table. First, using a 1.7L closed-type Banbury mixer, chemicals other than sulfur and vulcanization accelerator are mixed for 1 to 10 minutes until the discharge temperature reaches 150 to 160°C to obtain a mixture. Next, using a twin-screw open roll mixer, sulfur and vulcanization accelerator are added to the resulting mixture and mixed for 4 minutes until the temperature reaches 105°C to obtain an unvulcanized rubber composition. Using the obtained unvulcanized rubber composition, each tread component (tire size: 11R22.5) is manufactured by extruding it to the shape of the tread using an extruder equipped with a die of a predetermined shape and press-vulcanizing it for 12 minutes under conditions of 170°C. The joint surface of each tread component with the base tire is pre-buffed.

[0185] <Tyre> The base tire is prepared by bonding together the tire components, each with only the tread portion removed, to create a green tire for the base tire, and then press-vulcanizing it at 170°C for 12 minutes. The outermost surface of the base tire in the radial direction, i.e., the bonding surface with the new tread component, is pre-polished.

[0186] <Retreaded Tires> According to Table 2 or Table 4, a resin-based adhesive is applied to the joint surface of the base tire and the joint surface of the tread member to a predetermined thickness, and the joint surfaces of the two are brought together and bonded to obtain a retreaded tire.

[0187] [evaluation] For each retreaded tire, the results measured using the following method are recorded in the corresponding column of the table below. Unless otherwise specified, each retreaded tire is used after being brought back to its normal condition.

[0188] <70℃ tanδ> From the tread material of each retreaded tire, a vulcanized rubber test piece measuring 20 mm in length, 4 mm in width, and 1 mm in thickness is cut out as a measurement sample. The length direction of the sample is aligned with the tire's circumferential direction, and the thickness direction of the sample is aligned with the tire's radial direction. Using this sample, the loss tangent (tanδ) is measured using a dynamic viscoelasticity measuring device (GABO's Iplexer series) under the conditions of a temperature of 70°C, a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±1%, and the extension mode.

[0189] <Ride comfort performance> Each retreaded tire is fitted to all wheels of a passenger car with an engine displacement of 2000cc. This passenger car is driven at 100 km / h on an asphalt test course, and 20 test drivers subjectively evaluate the ride comfort. The evaluation is given as an integer value from 1 to 5 points, with higher scores indicating better ride comfort. The total score of each retreaded tire is indexed so that the total score of the standard comparison is 100.

[0190] [Table 1]

[0191] [Table 2]

[0192] [Table 3]

[0193] [Table 4]

[0194] [Embodiment] An example of a preferred embodiment is shown below.

[0195] <1> A retreaded tire comprising a base tire, a tread member, and an adhesive layer, The adhesive layer is placed between the base tire and the tread member. The tread member is made of a rubber composition, The aforementioned adhesive layer is made of a resin-based adhesive. A retreaded tire in which, when the thickness of the tread member (mm) is Tc, the thickness of the adhesive layer (mm) is Ta, and the loss tangent of the rubber composition at 70°C is 70°Ctanδ, the value of 70°Ctanδ × (Tc / Ta) is 4.00 or more, preferably 4.10 or more. <2> The rubber composition includes styrene-butadiene rubber, <1> The retreaded tires as described. <3> The rubber composition contains silica, <1> Or the above <2> The retreaded tires as described. <4> The average primary particle diameter of the silica is less than 17 nm, preferably less than 16 nm, and more preferably 15 nm or less. <3> The retreaded tires as described. <5> The above is characterized by Tc / Ta being greater than 25.0, preferably greater than 27.0, more preferably greater than 29.0, and even more preferably greater than 30.0. <1> ~ Above <4> A retreaded tire as described in any one of the following items. <6> Ta is less than 2.0, preferably less than 1.0, as described above. <1> ~ Above <5> A retreaded tire as described in any one of the following items. <7> The above is true if the value of 70℃ tanδ × (Tc / Ta) is 4.20 or higher, preferably 4.50 or higher. <1> ~ Above <6> A retreaded tire as described in any one of the following items. <8> The value of 70℃ tanδ × (Tc / Ta) is 5.00 or higher, preferably 5.20 or higher, more preferably 5.30 or higher, and even more preferably 5.40 or higher. <1> ~ Above <6> A retreaded tire as described in any one of the following items. <9> The glass transition temperature of the adhesive layer during curing is greater than 20°C, preferably greater than 30°C, more preferably greater than 40°C, and even more preferably greater than 50°C. <1> ~ Above <8> A retreaded tire as described in any one of the following items. <10> The above resin-based adhesive is a urethane-based adhesive. <1> ~ Above <9> A retreaded tire as described in any one of the following items. <11> The silica content in the rubber composition is 70 parts by mass or less, preferably less than 60 parts by mass, and more preferably 55 parts by mass or less, per 100 parts by mass of the rubber component. <3> Or the above <4> The retreaded tires as described. [Explanation of Symbols]

[0196] 1. Reconditioned tires 2 Tread Member 3 tires 4 Carcass 5 belts 6 Adhesive layer CL tire centerline Tc tread material thickness Thickness of the adhesive layer

Claims

1. A retreaded tire comprising a base tire, a tread member, and an adhesive layer, The adhesive layer is placed between the base tire and the tread member. The tread member is made of a rubber composition, The aforementioned adhesive layer is made of a resin-based adhesive. A retreaded tire in which, when the thickness of the tread member (mm) is Tc, the thickness of the adhesive layer (mm) is Ta, and the loss tangent of the rubber composition at 70°C is 70°C tanδ, the value of 70°C tanδ × (Tc / Ta) is 4.00 or greater.

2. The retreaded tire according to claim 1, wherein the rubber composition comprises styrene-butadiene rubber.

3. The retreaded tire according to claim 1 or 2, wherein the rubber composition contains silica.

4. The retreaded tire according to claim 3, wherein the average primary particle diameter of the silica is less than 17 nm.

5. A retreaded tire according to claim 1 or 2, wherein Tc / Ta is greater than 25.

0.

6. A retreaded tire according to claim 1 or 2, wherein Ta is less than 2.

0.

7. A retreaded tire according to claim 1 or 2, wherein the value of 70°C tanδ × (Tc / Ta) is 4.20 or greater.

8. A retreaded tire according to claim 1 or 2, wherein the value of 70°C tanδ × (Tc / Ta) is 5.00 or greater.

9. The retreaded tire according to claim 1 or 2, wherein the glass transition temperature of the adhesive layer during curing is greater than 20°C.

10. The retreaded tire according to claim 1 or 2, wherein the resin-based adhesive is a urethane-based adhesive.

11. The retreaded tire according to claim 3, wherein the silica content in the rubber composition is 70 parts by mass or less per 100 parts by mass of the rubber component.

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