tire

Abstract

A tire having excellent overall performance (in terms of handling stability on a worn wet road and handling stability on a worn icy road) is provided. The present invention relates to a tire having a tread portion having at least one main groove extending continuously in the tire circumferential direction; the tread portion comprises a rubber having a hardness of 58 or more at 60°C and a hardness of not more than 115% of the hardness at 0°C; and the S 50 / S0 ratio is greater than 1, where S0 represents the sea ratio (%) in the tread contact area of ​​a new tire, S 50 It indicates the sea ratio (%) when the tread portion is worn until the main groove depth reaches 50% of the main groove depth of a new tire.

Description

Technical Field

[0001] The present invention relates to a tire. Background Art

[0002] There has been a desire for a tire having various desirable properties (see, for example, Patent Document 1).

[0003] Reference List

[0004] Patent Literature

[0005] Patent Document 1: JP 2008-214377 A Summary of the invention

[0006] Technical issues

[0007] However, the inventors' research has revealed that the conventional technology has room for improvement in overall performance (in terms of handling stability on worn wet roads and handling stability on worn icy roads).

[0008] The present invention aims to solve this problem and provide a tire having excellent overall performance in terms of handling stability on worn wet roads and handling stability on worn icy roads.

[0009] Solutions to the problem

[0010] The present invention relates to a tire, comprising a tread portion.

[0011] The tread portion has at least one main groove extending continuously in the tire circumferential direction.

[0012] The tread portion includes a rubber having a hardness of 58 or more at 60° C. and a hardness of not more than 115% of the hardness at 0° C.,

[0013] The tread portion S 50 / S 0 The ratio is greater than 1, where S 0 Indicates the proportion of sea in the tread contact area of ​​a new tire (%), S 50 It indicates the sea ratio (%) when the tread portion is worn until the main groove depth reaches 50% of the main groove depth of a new tire.

[0014] Advantageous Effects of the Invention

[0015] The tire according to the present invention comprises a tread portion having at least one main groove extending continuously in the tire circumferential direction; the tread portion comprises rubber having a hardness at 60° C. or more that is a predetermined hardness and a hardness at 0° C. that is not more than a predetermined percentage of the hardness at 60° C.; and the S 50 / S 0The ratio is greater than 1, where S 0 Indicates the proportion of sea in the tread contact area of ​​a new tire (%), S 50 Indicates the sea ratio (%) when the tread portion is worn until the main groove depth reaches 50% of the main groove depth of a new tire. This tire has excellent overall performance (in terms of handling stability on wet roads after wear and handling stability on icy roads after wear). BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A cross-sectional view of a tread portion of a tire according to one embodiment of the present invention is shown.

[0017] Figure 2 An enlarged plan view of a main groove according to one embodiment of the present invention is shown.

[0018] Figure 3 Shows Figure 2 AA cross-section diagram.

[0019] Figure 4 An enlarged plan view of another main groove according to the present invention is shown.

[0020] Figure 5 (a) shows Figure 4 BB cross-section diagram, Figure 5 (b) shows Figure 4 CC cross-section diagram.

[0021] Figure 6 An enlarged plan view of another main groove according to the present invention is shown.

[0022] Figure 7 Shows Figure 6 DD cross-sectional view.

[0023] Figure 8 A schematic diagram illustrating the behavior of plasticizers in rubber is shown. DETAILED DESCRIPTION

[0024] The tire of the present invention has a tread portion. The tread portion has at least one main groove extending continuously in the tire circumferential direction. The tread portion contains rubber having a hardness of 58 or more at 60°C and a hardness of not more than 115% of the hardness at 0°C. 50 / S 0 The ratio is greater than 1, where S 0 Indicates the proportion of sea in the tread contact area of ​​a new tire (%), S 50It represents the sea ratio (%) when the tread portion is worn until the main groove depth reaches 50% of the main groove depth of a new tire. Therefore, the tire has excellent overall performance (in terms of handling stability on wet roads after wear and handling stability on icy roads after wear).

[0025] Here, the hardness is the JIS-A hardness of rubber at 0°C or 60°C.

[0026] The tire provides the above-mentioned effects. The reason why the tire provides such a beneficial effect is not completely clear, but the reason is presumed to be as follows.

[0027] Reliable drainage and rubber hardness are necessary to improve handling stability on wet roads. Conventional tires have their grooves (sea ratio) reduced after wear, which is disadvantageous for drainage. In contrast, the groove shape of the tread according to the present invention has a specific relationship between the sea ratio of a new tire and the sea ratio of a worn tire, that is, the grooves (sea ratio) in the tire groove shape increase as the tire wears, and the tread is formed of rubber that is hard at 60°C. Therefore, the tire can provide good handling stability on wet roads after wear.

[0028] At the same time, in order to improve the handling stability on icy roads, it is necessary to reduce the stiffness of the land portion of the tread and the hardness of the contact patch so that the tire fits the road surface as closely as possible between stepping in and pushing out. After conventional tires are worn, their grooves (sea ratio) will decrease, so the stiffness of the land portion will increase. In addition, for conventional rubber, the hardness of the contact patch at 0°C is higher than the hardness at 60°C. In contrast, the tread according to the present invention has a tire groove shape in which the groove (sea ratio) increases as the tire wears, and the tread is formed of a rubber whose hardness at 0°C is reduced to no more than a predetermined percentage of the hardness at 60°C, that is, the rubber is slightly softer at 0°C or slightly harder than it is at 60°C. Therefore, the tire can provide good handling stability on icy roads after wear.

[0029] Therefore, the present invention solves the problem (purpose) of improving overall performance (in terms of handling stability on a worn wet road and handling stability on a worn icy road) by formulating a tire that satisfies the hardness parameter and the sea ratio parameter. In other words, the parameter does not define the problem (purpose), the problem of this article is to improve overall performance (in terms of handling stability on a worn wet road and handling stability on a worn icy road). In order to solve this problem, the tire is formulated to satisfy the hardness parameter and the sea ratio parameter. Therefore, satisfying the hardness parameter and the sea ratio parameter is a necessary requirement.

[0030] Furthermore, in this article, the hardness of rubber refers to the hardness of vulcanized rubber.

[0031] The method for measuring hardness is described below.

[0032] Herein, the hardness of (vulcanized) rubber (JIS-A hardness) can be measured using a type A durometer at 0°C or 60°C according to JIS K 6253-3 (2012) "Rubber, vulcanized or thermoplastic rubber - Determination of hardness - Part 3: Durometer method".

[0033] The hardness of the rubber contained in the tread portion at 60° C. is 58 or more, preferably 59 or more. The upper limit is not limited, but is preferably 75 or less, more preferably 70 or less, further more preferably 65 or less, particularly preferably 62 or less, most preferably 61 or less, further most preferably 60 or less. When the hardness at 60° C. is within the above range, the beneficial effects tend to be more suitably achieved.

[0034] The hardness of the rubber contained in the tread portion at 0°C is not more than 115% of the hardness at 60°C, preferably not more than 110%, more preferably not more than 108%, and further more preferably not more than 107%. The lower limit is not limited, but is preferably not less than 90% of the hardness at 60°C, more preferably not less than 95%, further more preferably not less than 100%, particularly preferably not less than 102%, and most preferably not less than 103%. When the hardness at 0°C is within the above range, the beneficial effects tend to be more suitably achieved.

[0035] The tire has a tread portion, the tread portion has at least one main groove extending continuously in the tire circumferential direction, and the S 50 / S 0 The ratio is greater than 1, where S 0 Indicates the proportion of sea in the tread contact area of ​​a new tire (%), S 50 It indicates the sea ratio (%) when the tread portion is worn until the main groove depth reaches 50% of the main groove depth of a new tire. 50 / S 0 The ratio is preferably 1.05 or more, more preferably 1.07 or more, further more preferably 1.10 or more, particularly preferably 1.15 or more, most preferably 1.18 or more, and further most preferably 1.20 or more. The upper limit is not limited, but is preferably 1.40 or less, more preferably 1.37 or less, further more preferably 1.35 or less, particularly preferably 1.33 or less, most preferably 1.31 or less, and further most preferably 1.29 or less. When the ratio is within the above range, even if the tread portion is worn, the opening area of ​​the main groove on the tread surface of the tread portion can be ensured. Therefore, the beneficial effect tends to be more appropriately achieved.

[0036] S 50 (%) represents the sea ratio when the tread portion is worn until the main groove depth reaches 50% of the main groove depth of a new tire, S 50(%) is preferably 5 or more, more preferably 20 or more, further more preferably 25 or more, particularly preferably 30 or more, most preferably 35 or more, further most preferably 39 or more, further most preferably 41 or more. The upper limit is not limited, but is preferably 100 or less, more preferably 60 or less, further more preferably 50 or less, and particularly preferably 45 or less. When S 50 Within the above range, beneficial effects tend to be more suitably achieved.

[0037] As used herein, the term "sea ratio S 0 " refers to the ratio (%) of the total groove area of ​​all grooves that can be retained after the main grooves are worn out by 50% without changing the tread radius, relative to the entire tread contact area that would be obtained if all grooves in the tread portion were not provided, and the ratio is determined when the tire is a new tire. It should be noted that the total groove area therefore does not include the area of ​​the grooves that do not remain after the main grooves are worn out by 50% without changing the tread radius. In addition, the term "sea ratio S 50 ” refers to the ratio (%) of the total groove area of ​​all grooves that have remained after 50% wear of the main grooves without changing the tread radius, relative to the entire tread contact area that would be obtained in a state assuming that all grooves in the tread portion were not provided, the ratio being determined after 50% wear. Furthermore, herein, when the tread portion is provided with a plurality of main grooves of different depths, the term “main groove” refers to the deepest main groove among the main grooves.

[0038] Here, the term "entire tread contact area that would be obtained assuming that all grooves in the tread portion are not provided" refers to an area defined by the outline of the contact shape of the tire determined by transfer-coated ink to the tread portion as described later.

[0039] Sea ratio S 0 Ratio to sea 50 It can be determined by any method and can be calculated as described below. The ground contact shape of the tire can be determined as follows: the tire is mounted on a regular rim, the tire is kept at an internal pressure of 230 kPa when the tire is a passenger car tire or the tire is kept at a regular internal pressure (maximum internal pressure) when the tire is a light truck or van tire, ink is applied to the tread portion, and the tread portion is vertically pressed against paper or the like under a load of 70% (for passenger car tires) or 80% (for light truck or van tires) of the maximum load capacity to transfer the ink applied to the tread portion. Sea ratio S 0 The calculation can be performed as follows: the area defined by the contour of the contact shape is regarded as the entire tread contact area that would be obtained if all grooves were not provided, and in the portion without ink, the total groove area of ​​all grooves that can be retained after the main groove is worn 50% without changing the tread radius. In addition, the sea ratio S 50The calculation can be performed by a method similar to that described above: determine the total tread contact area that would be obtained if all grooves in the tread portion were not provided and determine the total groove area of ​​all grooves that would remain after the main grooves have worn 50% without changing the tread radius (determined after 50% wear).

[0040] Herein, the sea ratio can be calculated based on the entire tread contact area and the total groove area (each determined as described above) that would be obtained assuming that not all grooves are provided, using the following formula: total groove area / (entire tread contact area-total groove area)×100.

[0041] Next, the production guidelines for satisfying the hardness parameter and the sea ratio parameter will be described. For example, the tire structure mentioned below can be used to satisfy the sea ratio parameter. First, the production guidelines for satisfying the hardness parameter are described.

[0042] The hardness parameter, i.e., the hardness at 60°C is above 58 and the hardness at 0°C does not exceed 115% of the hardness at 60°C, indicates that the rubber is hard at 60°C and the hardness of the rubber at 0°C is reduced to a predetermined percentage of the hardness at 60°C, i.e., the rubber is slightly softer at 0°C or slightly harder than when it is at 60°C.

[0043] The rubber having such properties can be produced by using a material whose hydrophilicity changes with temperature, such as a polymer containing a group whose hydrophilicity changes with temperature, specifically a polymer composite material in which a group whose hydrophilicity changes with temperature is bonded to a conjugated diene polymer, more specifically a polymer composite material in which a group showing a lower critical solution temperature (LCST) in water is bonded to a conjugated diene polymer.

[0044] The fact that the polymer composite material added to the rubber exhibits hydrophobicity at 60°C (or can easily attract plasticizers such as oil to its surroundings) and hydrophilicity at 0°C (or can easily release plasticizers into the base rubber) can be used to achieve a rubber composition that has a normal hardness at 60°C and is softer or only slightly harder at 0°C than it is at 60°C.

[0045] For example, when a polymer composite added to rubber forms islands in a sea-island structure, e.g. Figure 8As shown, the group having LCST in the polymer composite material shows hydrophobicity at high temperature (e.g., 60°C) and can easily attract the plasticizer to its surroundings, so that the concentration of the plasticizer in the base rubber is reduced and the hardness of the rubber is increased. On the other hand, the group having LCST in the polymer composite material shows hydrophilicity at low temperature (e.g., 0°C) and can easily release the plasticizer into the base rubber, so that the concentration of the plasticizer in the base rubber is increased and the hardness of the rubber is reduced. Therefore, through the action of the polymer containing a group whose hydrophilicity changes with temperature, the plasticizer moves in the rubber with changes in ambient temperature. Accordingly, a rubber that meets the above-mentioned hardness parameters can be produced.

[0046] Here, the hardness (absolute value) of the rubber can be controlled by the type or amount of chemicals (especially rubber component, filler, plasticizer, silane coupling agent) added to the rubber composition. For example, by increasing the amount of filler or reducing the amount of plasticizer, the hardness tends to increase, while by reducing the amount of filler or increasing the amount of plasticizer, the hardness tends to decrease.

[0047] Rubbers meeting the above hardness parameters can be produced by other techniques, such as using materials with less temperature dependence of hardness instead of temperature-responsive materials (such as the above-mentioned polymers containing groups that change their hydrophilicity with temperature).

[0048] Examples of materials whose hardness has little temperature dependence include materials that are hard both at room temperature and at low temperatures (such as inorganic compounds) and materials that are soft both at room temperature and at low temperatures (such as oils).

[0049] Adding such a material in a sufficiently large amount to the rubber component can suppress the influence of the temperature dependence of the hardness of the rubber component, thereby reducing the difference between the hardness of the rubber at 0° C. and the hardness at 60° C. For example, by adding at least 300 parts by mass (relative to 100 parts by mass of the rubber component) of an inorganic compound (such as calcium carbonate or clay), the difference between the hardness of the rubber at 0° C. and the hardness at 60° C. can be reduced.

[0050] The rubber composition contained in the tread portion and chemicals that can be used for the rubber composition are described below.

[0051] (Material that changes its hydrophilicity with temperature)

[0052] First, a material that changes its hydrophilicity with temperature is described. The material can be any material that changes its hydrophilicity with temperature, including, for example, a polymer containing a group that changes its hydrophilicity with temperature. Specific examples of the polymer include polymer composites containing a group that changes its hydrophilicity with temperature.

[0053] A polymer composite material containing a group whose hydrophilicity changes with temperature is described below.

[0054] <Groups that change their hydrophilicity with temperature>

[0055] First, the groups whose hydrophilicity changes with temperature are described below.

[0056] Herein, the group that changes its hydrophilicity with temperature may be any group that changes its hydrophilicity with temperature, and is preferably a group that reversibly changes its hydrophilicity with temperature.

[0057] The group that reversibly changes its hydrophilicity with temperature changes can be a temperature-responsive polymer (temperature-responsive polymer group). In other words, a polymer composite containing a group that reversibly changes its hydrophilicity with temperature changes can refer to, for example, a polymer composite containing a group formed by a temperature-responsive polymer. Examples of such polymer composites include: a polymer composite grafted with a temperature-responsive polymer, a polymer composite containing a temperature-responsive polymer unit in the main chain, and a polymer composite containing a temperature-responsive polymer block in the main chain. These can be used alone or in combination of two or more.

[0058] The term "temperature-responsive polymer" refers to a material that undergoes a reversible change in conformation of a polymer chain associated with hydration and dehydration in response to temperature changes in water, thereby reversibly changing its hydrophilicity and hydrophobicity with temperature changes. It is known that such a reversible change is caused by a molecular structure containing a hydrophilic group capable of forming a hydrogen bond and a hydrophobic group that is difficult to be compatible with water in one molecule.

[0059] Then, the present inventors found that the temperature-responsive polymer exhibits reversible changes in hydrophilicity and hydrophobicity with temperature changes not only when in water but also when in a rubber composition. In addition, it has been found that a polymer composite material in which a conjugated diene polymer is combined with a group (temperature-responsive polymer group) that changes its hydrophilicity with temperature changes also exhibits reversible changes in hydrophilicity and hydrophobicity with temperature changes when in a rubber composition.

[0060] Known temperature-responsive polymers include polymers that exhibit a lower critical solution temperature (LCST, also called lower critical co-solvent temperature or lower critical solution temperature) in water and polymers that exhibit an upper critical solution temperature (UCST, also called upper critical co-solvent temperature or upper critical solution temperature) in water. These can be used alone or in combination of two or more.

[0061] Polymers that exhibit LCST become hydrophobic at temperatures above the LCST boundary because intramolecular or intermolecular hydrophobic interactions become stronger, leading to aggregation of polymer chains. On the other hand, they become hydrophilic at temperatures below the LCST because polymer chains become hydrated by binding to water molecules. Therefore, these polymers exhibit reversible phase transition behavior near the LCST.

[0062] In contrast, polymers showing UCST become hydrophobic and insoluble at temperatures below the UCST, and become hydrophilic and soluble at temperatures above the UCST. Therefore, these polymers exhibit reversible phase transition behavior near the UCST. The reason for this UCST-type behavior is believed to be that the intermolecular forces can be driven by hydrogen bonds between side chains with multiple amide groups.

[0063] In the polymer composite material, the group that reversibly changes its hydrophilicity with temperature is preferably a polymer that exhibits LCST. In other words, the group that changes its hydrophilicity with temperature is preferably a group that exhibits a lower critical solution temperature in water.

[0064] Herein, the group showing a lower critical solution temperature (LCST) in water refers to a group that exists in a polymer composite and that shows a lower critical solution temperature in water when the group is cut off from the polymer composite and the cut group (polymer) is introduced into water.

[0065] Likewise, herein, a group showing an upper critical solution temperature (UCST) in water refers to a group that is present in a polymer composite and that shows an upper critical solution temperature in water when the group is cut off from the polymer composite and the cut off group (polymer) is introduced into water.

[0066] Groups (polymers) showing LCST are described below.

[0067] The group (polymer) showing LCST may include a single group (polymer) or a combination of two or more groups (polymers).

[0068] The group (polymer) exhibiting LCST may be any group (polymer) exhibiting LCST. Preferably, it is poly(N-substituted (meth)acrylamide). Among poly(N-substituted (meth)acrylamide), a group represented by the following formula (I) is preferred:

[0069]

[0070] In the formula, n represents an integer from 1 to 1000; R 1 , R 2 and R 3Each independently represents a hydrogen atom or a hydrocarbon group, provided that R 1 or R 2 At least one non-hydrogen atom in R 1 and R 2 Can together form a ring structure.

[0071] Preferably, n is 3 or more, more preferably 5 or more, further more preferably 10 or more, particularly preferably 20 or more, but is preferably 500 or less, more preferably 300 or less, further more preferably 150 or less, particularly preferably 80 or less, most preferably 40 or less, further most preferably 30 or less. When n is within the above range, the beneficial effects tend to be better achieved.

[0072] For R 1 and R 2 The hydrocarbon group may have any number of carbon atoms. The number of carbon atoms is preferably 1 or more, more preferably 2 or more, and further more preferably 3 or more, but is preferably 20 or less, more preferably 18 or less, further more preferably 14 or less, particularly preferably 10 or less, most preferably 6 or less, and further most preferably 4 or less. When the number of carbon atoms is within the above range, the beneficial effects tend to be better achieved.

[0073] For R 1 and R 2 Examples of the hydrocarbon group include: alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, neopentyl, isopentyl and n-hexyl; cycloalkyl groups such as cyclohexyl; and aryl groups such as methylphenyl and ethylphenyl. Among these, alkyl groups and cycloalkyl groups are preferred, and alkyl groups are more preferred.

[0074] By R 1 and R 2 The number of carbon atoms in the formed ring structure is preferably 3 or more, more preferably 4 or more, but is preferably 7 or less, more preferably 5 or less. When the number of carbon atoms is within the above range, the advantageous effects tend to be better achieved.

[0075] For R 1 and R 2 The hydrocarbon group may be a branched hydrocarbon group or an unbranched hydrocarbon group, and is preferably a branched hydrocarbon group.

[0076] Preferably, R 1 and R 2 are each a hydrogen atom, an alkyl group (particularly a branched alkyl group) or a cycloalkyl group, or R 1 and R 2 More preferably, R 1 and R 2It is any combination shown in Table 1, more preferably a combination of a hydrogen atom and an alkyl group (particularly a branched alkyl group), and particularly preferably a combination of a hydrogen atom and a propyl group (particularly an isopropyl group).

[0077] [Table 1]

[0078] Table 1: Chemical structures and LCST of preferred poly(N-substituted acrylamides)

[0079]

[0080] For R 3 The hydrocarbon group may have any number of carbon atoms. The number of carbon atoms is preferably 1 or more, but is preferably 5 or less, more preferably 3 or less, further more preferably 2 or less, and particularly preferably 1. When the number of carbon atoms is within the above range, the beneficial effects tend to be better achieved.

[0081] For R 3 Examples of the hydrocarbon group include 1 and R 2 Of these, alkyl is preferred.

[0082] For R 3 The hydrocarbon group may be a branched hydrocarbon group or an unbranched hydrocarbon group.

[0083] R 3 It is preferably a hydrogen atom or an alkyl group, and more preferably a hydrogen atom.

[0084] Examples of groups of formula (I) include: poly(N-alkylacrylamide) polymers, such as poly(N-isopropylacrylamide), poly(N-ethylacrylamide), poly(N-n-propylacrylamide), poly(N-ethyl, N-methylacrylamide), poly(N,N-diethylacrylamide), poly(N-isopropyl, N-methylacrylamide), poly(N-cyclopropylacrylamide), poly(N-acryloylpyrrolidine) and poly(N-acryloylpiperidine); and poly(N-alkylmethacrylamide) polymers, such as poly(N-isopropylmethacrylamide), poly(N-ethylmethacrylamide), poly(N-n-propylmethacrylamide), poly(N-ethyl, N-methylmethacrylamide), poly(N,N-diethylmethacrylamide), poly(N-isopropyl, N-methylmethacrylamide), poly(N-cyclopropylmethacrylamide), poly(N-methylacrylpyrrolidine) and poly(N-methacryloylpiperidine). These can be used alone or in combination of two or more. Among these, poly(N-isopropylacrylamide), poly(N,N-diethylacrylamide), poly(N-n-propylacrylamide) and poly(N-isopropyl, N-methylacrylamide) are preferred; among these, poly(N-isopropylacrylamide) (PNIPAM) is more preferred.

[0085] PNIPAM is a thermosensitive material that exhibits large surface energy changes in response to small temperature changes. For example, see N. Mori et al., Temperature Induced Changes in the Surface Wettability of SBR+PNIPA Films, 292, Macromol. Mater. Eng. 917, 917-22 (2007).

[0086] PNIPAM has a hydrophobic isopropyl group on the side chain and a hydrophilic amide bond at the base of the isopropyl group.

[0087] PNIPAM becomes soluble in water at temperatures below 32°C, where the hydrophilic amide bond portion forms hydrogen bonds with water molecules. On the other hand, at temperatures not lower than 32°C, the hydrogen bonds break due to the violent thermal motion of the molecules, and the hydrophobic interaction within or between molecules becomes stronger due to the hydrophobic isopropyl portion in the side chain, resulting in the aggregation of the polymer chains, making PNIPAM insoluble in water.

[0088] As mentioned above, the LCST (ie, the switching temperature from the hydrophilic state to the hydrophobic state) of PNIPAM is about 32°C.

[0089] The contact angle of a water drop placed on a PNIPAM polymer film changes dramatically above and below the LCST temperature. For example, the contact angle of a water drop placed on a PINPAM film is about 60° (hydrophilic) below 32°C, and then when it is heated to a temperature above 32°C, the contact angle exceeds about 93° (hydrophobic).

[0090] Polymer composites containing PNIPAM groups, which greatly change surface characteristics from hydrophilic to hydrophobic at about 32° C., can be used as polymer composites for rubber compositions to reversibly change tire performance in response to temperature changes.

[0091] Although the group (polymer) showing LCST may be suitably the group as described above, it is more preferably a poly(alkyl vinyl ether), and further more preferably a group represented by the following formula (A). In this case, the beneficial effects tend to be more suitably achieved. These groups may be used alone or in combination of two or more.

[0092]

[0093] In the formula, m represents an integer from 1 to 1000, R 4 , R 5 and R 6 Each independently represents a hydrogen atom or a hydrocarbon group.

[0094] Preferably, m is 3 or more, more preferably 5 or more, further more preferably 10 or more, particularly preferably 20 or more, but is preferably 500 or less, more preferably 300 or less, further more preferably 150 or less, particularly preferably 80 or less, most preferably 40 or less, further most preferably 30 or less. When m is within the above range, the beneficial effects tend to be better achieved.

[0095] For R 4 The hydrocarbon group may have any number of carbon atoms. The number of carbon atoms is preferably 1 or more, more preferably 2 or more, but is preferably 20 or less, more preferably 18 or less, further more preferably 14 or less, particularly preferably 10 or less, most preferably 6 or less, further most preferably 4 or less. When the number of carbon atoms is within the above range, the beneficial effects tend to be better achieved.

[0096] For R 5 and R 6 The hydrocarbon group may have any number of carbon atoms. The number of carbon atoms is preferably 1 or more, but is preferably 5 or less, more preferably 3 or less, further more preferably 2 or less, and particularly preferably 1. When the number of carbon atoms is within the above range, the beneficial effects tend to be better achieved.

[0097] For R 4 , R 5 and R 6 Examples of the hydrocarbon group include: alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, neopentyl, isopentyl and n-hexyl; cycloalkyl groups such as cyclohexyl; and aryl groups such as methylphenyl and ethylphenyl. Among these, alkyl groups and cycloalkyl groups are preferred, and alkyl groups are more preferred.

[0098] Preferably, R 4 is an alkyl group, R 5 and R 6 is a hydrogen atom. More preferably, R 4 Ethyl, R 5 and R 6 A hydrogen atom.

[0099] Examples of the group of formula (A) include poly(methyl vinyl ether), poly(ethyl vinyl ether), poly(propyl vinyl ether), poly(butyl vinyl ether), poly(pentenyl ether), poly(hexyl vinyl ether), poly(heptyl vinyl ether), poly(octyl ether) and poly(ethoxyethyl vinyl ether). These may be used alone or in combination of two or more. Among these, poly(ethyl vinyl ether) (PEVE) is preferred. Extensive studies by the present inventors have shown that PEVE exhibits an LCST of -20 to +5°C.

[0100] Examples of the group (polymer) showing LCST other than the group of formula (I) and the group of formula (A) include poly(N-vinyl-caprolactam) represented by the following formula (II) (LSCT: about 31°C), poly(2-alkyl-2-oxazoline) represented by the following formula (III) (LSCT: about 62°C when R is ethyl, about 36°C when R is isopropyl, and about 25°C when R is n-propyl), alkyl-substituted cellulose (e.g., methyl cellulose represented by the following formula (IV) (LSCT: about 50°C), hydroxypropyl cellulose, hydroxyethyl methyl cellulose, and hydroxypropyl methyl cellulose), poly(N-ethoxyethyl acrylamide) (LSCT: about 35°C), poly(N-ethoxyethyl methacrylamide) (LSCT: about 4 5°C), poly(N-tetrahydrofurfuryl acrylamide) (LSCT: about 28°C), poly(N-tetrahydrofurfuryl methacrylamide) (LSCT: about 35°C), polyvinyl methyl ether, poly[2-(dimethylamino)ethyl methacrylate], poly(3-ethyl-N-vinyl-2-pyrrolidone), hydroxybutyl chitosan, polyoxyethylene (20) sorbitan monostearate, polyoxyethylene (20) sorbitan monolaurate, polyoxyethylene (20) sorbitan monooleate, poly(ethylene glycol) methacrylate containing 2 to 6 ethylene glycol units, polyethylene glycol-co-polypropylene glycol (preferably those containing 2 to 8 ethylene glycol units and 2 to 8 polypropylene units, more preferably a compound represented by formula (A)), ethoxylated iso-C 13 H 27 -alcohol (preferably having an ethoxylation degree of 4 to 8), polyethylene glycol containing 4 to 50, preferably 4 to 20 ethylene glycol units, polypropylene glycol containing 4 to 30, preferably 4 to 15 propylene glycol units, monomethyl ether, dimethyl ether, monoethyl ether or diethyl ether of polyethylene glycol containing 4 to 50, preferably 4 to 20 ethylene glycol units, and monomethyl ether, dimethyl ether, monoethyl ether or diethyl ether of polypropylene glycol containing 4 to 50, preferably 4 to 20 propylene glycol units. These may be used alone or in combination of two or more.

[0101] (A)HO-[-CH 2 -CH 2 -O] x -[-CH(CH 3 )-CH 2 -O] y -[-CH 2 -CH 2 -O] z -H

[0102] wherein y is 3 to 10, and x and z are each 1 to 8, provided that y+x+z is 5 to 18.

[0103]

[0104] In formulae (II) to (IV), n is as defined for n in formula (I). In formula (III), R is an alkyl group selected from n-propyl, isopropyl or ethyl.

[0105] Although the group (polymer) showing LCST may suitably be the group as described above, it is also preferably a group represented by the following formula (B). In this case, beneficial effects tend to be more suitably achieved. These groups may be used alone or in combination of two or more.

[0106]

[0107] In the formula, m represents an integer from 1 to 1000, R 7 , R 8 and R 9 Each independently represents a hydrogen atom or a hydrocarbon group.

[0108] Preferably, m is 3 or more, more preferably 5 or more, further more preferably 10 or more, particularly preferably 20 or more, but is preferably 500 or less, more preferably 300 or less, further more preferably 150 or less, particularly preferably 80 or less, most preferably 40 or less, further most preferably 30 or less. When m is within the above range, the beneficial effects tend to be better achieved.

[0109] For R 7 The hydrocarbon group may have any number of carbon atoms. The number of carbon atoms is preferably 1 or more, more preferably 2 or more, but is preferably 20 or less, more preferably 18 or less, further more preferably 14 or less, particularly preferably 10 or less, most preferably 6 or less, further most preferably 4 or less. When the number of carbon atoms is within the above range, the beneficial effects tend to be better achieved.

[0110] For R 8 and R 9 The hydrocarbon group may have any number of carbon atoms. The number of carbon atoms is preferably 1 or more, but is preferably 5 or less, more preferably 3 or less, further more preferably 2 or less, and particularly preferably 1. When the number of carbon atoms is within the above range, the beneficial effects tend to be better achieved.

[0111] For R ７ , R 8 and R 9 Examples of the hydrocarbon group include: alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, neopentyl, isopentyl and n-hexyl; cycloalkyl groups such as cyclohexyl; and aryl groups such as methylphenyl and ethylphenyl. Among these, alkyl groups and cycloalkyl groups are preferred, and alkyl groups are more preferred.

[0112] Preferably, R 7 is an alkyl group, R 8 and R 9 is a hydrogen atom. More preferably, R 7 is n-propyl or isopropyl, R 8 and R ９ A hydrogen atom.

[0113] Examples of groups of formula (B) include: poly(isopropylvinyl acrylamide) (PNIPVM, R ７ is isopropyl, R 8 and R 9 is a hydrogen atom), poly(n-propylvinyl acrylamide) (PNNPAM, R ７ is n-propyl, R 8 and R 9 is a hydrogen atom), poly(n-butyl vinyl acrylamide) (R ７ is n-butyl, R 8 and R 9 is a hydrogen atom), poly(tert-butyl vinyl acrylamide) (R ７ is tert-butyl, R 8 and R 9 is a hydrogen atom), poly(sec-butyl vinyl acrylamide) (R ７ is sec-butyl, R 8 and R 9 is a hydrogen atom), poly(methyl vinyl acrylamide) (R 7 is methyl, R 8 and R 9 is a hydrogen atom), poly(ethyl vinyl acrylamide) (R ７ Ethyl, R 8 and R 9 is a hydrogen atom), poly(n-pentyl vinyl acrylamide) (R ７ is n-pentyl, R 8 and R 9 is a hydrogen atom), and poly(isoamyl vinyl acrylamide) (R ７ is isopentyl, R 8 and R 9 is a hydrogen atom). These can be used alone or in combination of two or more. Among these, PNIPVM, PNNPAM, poly(n-butylvinyl acrylamide) and poly(tert-butylvinyl acrylamide) are preferred, and PNIPVM or PNNPAM is more preferred. Extensive studies by the present inventors have shown that PNIPVM exhibits an LCST of 39°C and PNNPAM exhibits an LCST of 32°C.

[0114] Examples of the group showing LCST (material or polymer whose hydrophilicity changes with temperature) other than the above groups include: a copolymer of N-isopropylacrylamide and butyl acrylate, a block copolymer of N-isopropylacrylamide and polyethylene oxide, a copolymer of N-isopropylacrylamide and a fluorine monomer, a polymer composite of poly-N-acetylacrylamide and polyethylene oxide, a polymer composite of poly-N-acetylacrylamide and polyacrylamide, a copolymer of N-acetylacrylamide and acrylamide and a polymer composite of polyacrylamide, a copolymer of N-acryloylglycinamide and N-acetylacrylamide, a copolymer of 2-methoxyethyl acrylate and N,N-dimethylacrylamide, a copolymer of a compound represented by the following formula 1 and N,N-dimethylacrylamide, poly(N,N-dimethyl(acrylamidopropyl)propanesulfate), N,N-diethylacrylamide and maleic anhydride, a copolymer of N,N-diethylacrylamide and dimethyl fumarate, a copolymer of N,N-diethylacrylamide and hydroxyethyl methacrylate, a copolymer of N,N-diethylacrylamide and butadiene, a polymer composite material of polyvinyl alcohol or polyvinyl alcohol hydrolyzate and polyacrylamide, N-acryloyl-(2S)-2-aminoglutaramide polymer, N-acryloylglutamine-(2S)-2-aminoglutaramide polymer, N-methacryloyl-(2S)-2-aminoglutaramide polymer, a copolymer of N-acryloylglycinamide and a biotin methacrylamide derivative, a copolymer of N-acryloylglycinamide and N-acryloyl-(2S)-2-aminoglutaramide, biotin-immobilized temperature-responsive magnetic fine particles (making N-acryloylglycinamide, methacrylated magnetic fine particles (methacrylated magnetic fine particles fine particles produced by the reaction of poly(sulfobetaine methacrylamide), copolymers of N-vinyl-n-butylamide and maleic anhydride, copolymers of N-vinyl-n-butylamide and dimethyl fumarate, copolymers of N-vinyl-n-butylamide and hydroxyethyl methacrylate, copolymers of N-vinyl-n-butylamide and butadiene, polyester amides, polyether amides, copolymers of ethylene oxide and propylene oxide, monoamines of copolymers of ethylene oxide and propylene oxide, polyethylene oxide-poly Propylene oxide-polyethylene oxide block copolymer, polymer composite material of polyethylene oxide and polyvinyl alcohol, polypropylene oxide modified by maltopentaose, poly(lactide-co-glycolide)-polyethylene oxide-polylactide triblock copolymer, copolymer of 2-methoxyethyl acrylate and acryloylmorpholine, copolymer of 2-methoxyethyl acrylate and N-vinyl pyrrolidone, copolymer of 2-methoxyethyl acrylate and 2-hydroxyethyl acrylate, copolymer of 2-methoxyethyl acrylate and methoxytriethylene glycol acrylate,Poly[2-(2-ethoxyethoxy)ethyl acrylate], poly(2-(2-ethoxyethoxy)ethyl acrylate-co-2-(methoxyethoxy)ethyl methacrylate), poly(2-(N,N-dimethylaminoethyl)methacrylate), copolymer of N-vinyl caprolactam and hydroxyethyl methacrylate, copolymer of methyl vinyl ether and hydroxyethyl methacrylate, N-vinyl caprolactam polymer, copolymer of N-vinyl caprolactam and maleic anhydride, copolymer of N-vinyl caprolactam and dimethyl fumarate, copolymer of N-vinyl caprolactam and butadiene, N-vinyl Copolymers of vinyl caprolactam, vinyl pyrrolidine and glycidyl methacrylate, copolymers of N-vinyl caprolactam, vinyl pyrrolidine and methacrylic acid, copolymers of N-vinyl caprolactam, vinyl pyrrolidone and α, α-dimethyl-m-isopropenyl benzyl isocyanate, copolymers of N-vinyl caprolactam, vinyl pyrrolidone and hydroxyethyl methacrylate, poly(1-ethyl-3-vinyl-2-imidazolidinone), poly(1-methyl-3-vinyl-2-imidazolidinone), poly(1-n-propyl-3-vinyl-2-imidazolidinone), poly(1-isopropyl-3-vinyl-2-imidazolidinone) oxazolidinone), poly(1-acetyl-3-vinyl-2-imidazolidinone), poly(1-propionyl-3-vinyl-2-imidazolidinone), a copolymer represented by the following formula 2, a poly(N-vinyl-2-imidazolidinone compound), a copolymer of 2-hydroxyethyl vinyl ether and vinyl acetate, a copolymer of diethylene glycol monovinyl ether and vinyl acetate, a copolymer of methyl vinyl ether and maleic anhydride, a copolymer of methyl vinyl ether and dimethyl fumarate, a carbamylated polyamino acid, a polymer of a compound represented by the following formula 3, a polymer of a compound represented by the following formula 4, having [N-(2-hydroxyethyl)- L-glutamine] side groups, poly(orthoesters), polyacetal-poly[N-(2-hydroxyethyl)-L-glutamine]-polyacetal triblock copolymers, poly[N-(2-hydroxyethyl)-L-glutamine]-poly(orthoesters)-poly[N-(2-hydroxyethyl)-L-glutamine] triblock copolymers, poly[N-(2-hydroxyethyl)-L-glutamine]-polyacetal diblock copolymers, amino-terminated poly[N-(2-hydroxyethyl)-L-glutamine], amino-terminated poly(orthoesters), amino-terminated polyacetals, cellulose triacetate, magnetic nanoparticles, amino-containing polystyrene, and glycoluril polymers. These can be used alone or in combination of two or more. ,

[0115]

[0116] The weight average molecular weight of the group whose hydrophilicity changes with temperature (the group formed by the temperature responsive polymer) is preferably 330 or more, more preferably 560 or more, and further more preferably 1130 or more, but is preferably 57000 or less, more preferably 34000 or less, and further more preferably 17000 or less. When the weight average molecular weight is within the above range, the beneficial effects tend to be better achieved.

[0117] The phase transition temperature (lower critical solution temperature (LCST) or upper critical solution temperature (UCST)) of the temperature-responsive polymer is preferably -50°C or higher, more preferably -40°C or higher, further more preferably -30°C or higher, particularly preferably -25°C or higher, but preferably 60°C or lower, more preferably 50°C or lower, further more preferably 40°C or lower, particularly preferably 35°C or lower, most preferably 30°C or lower, further most preferably 25°C or lower, further most preferably 20°C or lower. When the phase transition temperature is within the above range, the beneficial effects tend to be better achieved.

[0118] In this article, the phase transition temperature of the temperature-responsive polymer is measured using a temperature-controlled spectrophotometer. An aqueous solution of the temperature-responsive polymer adjusted to 10% by mass can be placed in a cell, which can then be covered with paraffin film to prevent vaporization, and an in-cell temperature sensor can be installed. The experiment can be carried out under the conditions of a measuring wavelength of 600nm, a collection temperature of 0.1°C, and a heating rate of 0.1°C. The temperature at which the transmittance reaches 90% is defined as the phase transition temperature.

[0119] Here, the temperature responsive polymer refers to a temperature responsive polymer group (temperature responsive polymer) obtained by cutting from a polymer composite material containing the temperature responsive polymer group.

[0120] <Method for producing polymer composite material>

[0121] For example, the polymer composite material can be formed by stirring a conjugated diene polymer having a weight average molecular weight of 100,000 or more (determined by gel permeation chromatography), a free radical generator, and a reactant having at least one heteroatom and at least one carbon-carbon double bond in at least one solvent (selected from hydrocarbon solvents, aromatic solvents, and aprotic polar solvents) at a temperature of at least 40°C but not higher than 200°C.

[0122] Here, the polymer composite material can be produced by a known synthesis technique. For example, the polymer composite material can be produced with reference to JP 2005-314419A, JP 2016-505679T, JP 2015-531672T, JP 2003-252936A, JP 2004-307523A, etc.

[0123] <<Conjugated diene polymer>>

[0124] The weight average molecular weight (Mw) of the conjugated diene polymer determined by gel permeation chromatography is 100,000 or more, preferably 200,000 or more, more preferably 300,000 or more, further more preferably 400,000 or more, particularly preferably 500,000 or more, and most preferably 600,000 or more. The upper limit is not limited, but is preferably 4,000,000 or less, more preferably 3,000,000 or less, further more preferably 2,000,000 or less, and particularly preferably 1,200,000 or less. When Mw is within the above range, the beneficial effects tend to be better achieved.

[0125] Herein, Mw and number average molecular weight (Mn) can be determined by gel permeation chromatography (GPC-8000 series, available from Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M available from Tosoh Corporation) calibrated with polystyrene standards.

[0126] The non-limiting examples of conjugated diene polymers include diene rubbers commonly used as rubber components in tire compositions, such as isoprene rubber, polybutadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR) and butyl rubber (IIR). These can be used alone or in combination of two or more. Among these, preferably isoprene rubber, BR and SBR, more preferably BR or SBR, further more preferably SBR.

[0127] The conjugated diene polymer may be a commercially available product, or may be polymerized according to a known method or other methods.

[0128] The diene rubber may be an unmodified polymer or a modified polymer.

[0129] The modified polymer may be any polymer (preferably a diene rubber) having a functional group that interacts with a filler (e.g., silica). Examples include: a chain end-modified polymer obtained by modifying at least one chain end of a polymer with a compound (modifier) ​​having the above functional group (i.e., a chain end-modified polymer terminated with the above functional group); a main chain-modified polymer having the above functional group in the main chain; a main chain and chain end-modified polymer having the above functional group in both the main chain and the chain end (e.g., a main chain having the above functional group and at least one chain end being modified by the above modifier); and a chain end-modified polymer in which a hydroxyl group or an epoxy group is introduced by modification (coupling) with a polyfunctional compound having two or more epoxy groups in the molecule. These may be used alone or in combination of two or more.

[0130] Examples of the above functional groups include amino, amide, silyl, alkoxysilyl, isocyanate, imino, imidazole, urea, ether, carbonyl, oxycarbonyl, mercapto, sulfide, disulfide, sulfonyl, sulfinyl, thiocarbonyl, ammonium, imido, hydrazine, azo, diazo, carboxyl, nitrile, pyridyl, alkoxy, hydroxyl, oxy and epoxy. Here, these functional groups can be substituted. These can be used alone or in combination of two or more. Among these, amino (preferably amino having hydrogen atoms substituted by C1-C6 alkyl), alkoxy (preferably C1-C6 alkoxy) and alkoxysilyl (preferably C1-C6 alkoxysilyl) are preferred.

[0131] Any SBR may be used. Examples include emulsion polymerized styrene-butadiene rubber (E-SBR) and solution polymerized styrene-butadiene rubber (S-SBR). These may be used alone or in combination of two or more.

[0132] The styrene content of SBR is preferably 5% by mass or more, more preferably 10% by mass or more, further more preferably 15% by mass or more, and particularly preferably 20% by mass or more. The styrene content is also preferably 60% by mass or less, more preferably 50% by mass or less, further more preferably 40% by mass or less, and particularly preferably 30% by mass or less. When the styrene content is within the above range, the beneficial effects tend to be better achieved.

[0133] In this article, the styrene content of SBR can be 1 It was determined by H-NMR analysis.

[0134] SBR products manufactured or sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Zeon Corporation, etc. can be used as SBR.

[0135] SBR can be non-modified SBR or modified SBR. Examples of modified SBR include those in which the functional groups listed for modified polymers are introduced. Among these, non-modified SBR is preferred.

[0136] Any BR can be used. Examples include high cis BR with a high cis content, BR containing syndiotactic polybutadiene crystals, and BR synthesized using a rare earth catalyst (rare earth-catalyzed BR). These can be used alone or in combination of two or more. Among these, rare earth-catalyzed BR is preferred.

[0137] The cis content of BR is preferably 90% by mass or more, more preferably 95% by mass or more. There is no upper limit. When the cis content is within the above range, the beneficial effects tend to be better achieved.

[0138] Here, the cis content can be measured by infrared absorption spectroscopy.

[0139] Furthermore, BR may be non-modified BR or modified BR. Examples of modified BR include those into which the functional groups listed for the modified polymer are introduced. Among these, non-modified BR is preferred.

[0140] Examples of commercially available BR include those available from Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Zeon Corporation, and the like.

[0141] Examples of isoprene-based rubbers include natural rubber (NR), polyisoprene rubber (IR), modified NR, modified NR and modified IR. Examples of NR include those commonly used in the tire industry, such as SIR20, RSS#3 and TSR20. Any IR can be used, including, for example, those commonly used in the tire industry, such as IR2200. Examples of modified NR include deproteinized natural rubber (DPNR) and highly purified natural rubber (UPNR). Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR) and grafted natural rubber. Examples of modified IR include epoxidized polyisoprene rubber, hydrogenated polyisoprene rubber and grafted polyisoprene rubber. These can be used alone or in combination of two or more. Among these, NR is preferred.

[0142] <Free Radical Generator>

[0143] Any radical generator may be used, including, for example, those generally used as radical initiators, such as azo compounds, organic oxides, dihalogens, and redox initiators. These may be used alone or in combination of two or more.

[0144] Azo compounds can be any compound containing an azo bond. Examples include azobisisobutyronitrile (AIBN), azodicarbonamide, 2,2'-azobis-(2-amidinopropane) dihydrochloride, 2,2'-azobis(isobutyric acid) dimethyl ester, azobiscyanovaleric acid, 1,1'-azobis-(2,4-dimethylvaleronitrile), azobismethylbutyronitrile and 2,2'-azobis-(4-methoxy-2,4-dimethylvaleronitrile). These can be used alone or in combination of two or more. Among these, azobisisobutyronitrile (AIBN) is preferred.

[0145] Any organic oxide can be used, including, for example, di-tert-butyl peroxide, tert-butyl hydroperoxide, p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, diisopropylbenzene hydroperoxide, acetylcyclohexanesulfonyl peroxide, diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, benzoyl peroxide and lauroyl peroxide. Examples of azo compounds include azobisisobutyronitrile, azobismethoxydimethylvaleronitrile, azobisdimethylvaleronitrile and azobisaminopropane hydrochloride. These can be used alone or in combination of two or more.

[0146] Any dihalogen may be used, including, for example, chlorine, bromine, and iodine. These may be used alone or in combination of two or more.

[0147] The redox initiator may be any combination of a peroxide and a reducing agent, examples of which include a combination of hydrogen peroxide and an iron (II) salt, and a combination of a peroxide salt (eg, potassium peroxodisulfate) and sodium bisulfite. These may be used alone or in combination of two or more.

[0148] Among the radical generators, azo compounds are preferred, and azobisisobutyronitrile (AIBN) is more preferred.

[0149] <Reactant having at least one heteroatom and at least one carbon-carbon double bond>

[0150] The reactant having at least one heteroatom and at least one carbon-carbon double bond may be any reactant having at least one heteroatom and at least one carbon-carbon double bond. Such reactants may be used alone or in combination of two or more.

[0151] Any heteroatom may be used, including, for example, oxygen atoms, nitrogen atoms, silicon atoms, and sulfur atoms. Of these, the reactant preferably has an oxygen atom and a nitrogen atom, and more preferably has one oxygen atom and one nitrogen atom.

[0152] The number of carbon-carbon double bonds in the reactants is not limited, but is preferably one.

[0153] Specifically, the reactant can be any compound that can form the above-mentioned group whose hydrophilicity changes with temperature (temperature responsive polymer (temperature responsive polymer group)), preferably a compound that can form a group whose hydrophilicity changes with temperature (temperature responsive polymer (temperature responsive polymer group)) through free radical polymerization.

[0154] Since the characteristic of the temperature-responsive polymer is a structure containing both a hydrophobic group and a hydrophilic group, the compound (monomer) capable of forming the temperature-responsive polymer must have at least one heteroatom.

[0155] The above-mentioned reactant is preferably a compound that can form a group showing a lower critical solution temperature in water, more preferably a compound that can form a poly(N-substituted (meth)acrylamide), further more preferably a compound that can form a group represented by formula (I), and particularly preferably a compound that can form a poly(N-isopropylacrylamide).

[0156] For example, a polymer composite material having PNIPAM can be produced by using isopropylacrylamide (NIPAM), which is a monomer forming PNIPAM, as the above-mentioned reactant.

[0157] More specific examples of the above reactants include:

[0158] Alkyl acrylamides, such as isopropyl acrylamide (NIPAM) (which is a monomer forming PNIPAM), ethyl acrylamide, n-propyl acrylamide (NNPAM) (which is a monomer forming PNNPAM), ethyl methacrylamide, diethyl acrylamide (NDEAM) (which is a monomer forming PNDEAM), isopropyl methacrylamide (NMNIPAM) (which is a monomer forming PNMNIPAM), cyclopropyl acrylamide, acryloyl pyrrolidine and acryloyl piperidine;

[0159] Alkyl methacrylamides, such as isopropyl methacrylamide, ethyl methacrylamide, n-propyl methacrylamide, ethyl, methyl methacrylamide, diethyl methacrylamide, isopropyl, methyl methacrylamide, cyclopropyl methacrylamide, methacrylpyrrolidine and methacrylpiperidine;

[0160] Alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, pentenyl ether, hexyl vinyl ether, heptyl vinyl ether and octyl ether; and

[0161] Monomers of vinyl-caprolactam, 2-alkyl-2-oxazolines, ethoxyethyl acrylamide, ethoxyethyl methacrylamide, tetrahydrofurfuryl acrylamide, tetrahydrofurfuryl methacrylamide, vinyl methyl ether, 2-(dimethylamino)ethyl methacrylate, 3-ethyl-N-vinyl-2-pyrrolidone and epoxide / allyl glycidyl ether copolymers.

[0162] These can be used alone or in combination of two or more. Among these, alkyl acrylamide is preferred. Isopropyl acrylamide (NIPAM), n-propyl acrylamide (NNPAM), diethyl acrylamide (NDEAM) and isopropyl methacrylamide (NMNIPAM) are more preferred, and isopropyl acrylamide (NIPAM) is further preferred.

[0163] Furthermore, alkyl vinyl ethers are preferred, methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, pentenyl ether, hexyl vinyl ether, heptyl vinyl ether and octyl ether are more preferred, and ethyl vinyl ether (EVE) is further more preferred.

[0164] <Solvent>

[0165] Any solvent may be used, including, for example, at least one solvent selected from hydrocarbon solvents, aromatic solvents, and aprotic polar solvents. These may be used alone or in combination of two or more. The solvent may be appropriately selected according to the free radical generation temperature of the free radical generator used.

[0166] Any hydrocarbon solvent may be used, including, for example, linear hydrocarbon solvents (eg, pentane, hexane, heptane, and octane) and cyclic hydrocarbon solvents (eg, cyclohexane and terpene solvents). These may be used alone or in combination of two or more.

[0167] Any aromatic solvent may be used, including, for example, aromatic hydrocarbon solvents (eg, benzene, toluene, ethylbenzene, and xylene) and heterocyclic aromatic solvents (eg, pyridine). These may be used alone or in combination of two or more.

[0168] Any aprotic polar solvent may be used, including, for example, diethyl ether, tetrahydrofuran, dimethyl sulfoxide, dimethylformamide, and dimethylacetamide. These may be used alone or in combination of two or more.

[0169] Among the solvents, hydrocarbon solvents are preferred, linear hydrocarbon solvents or cyclic hydrocarbon solvents are more preferred, and hexane or cyclohexane is still more preferred.

[0170] Furthermore, an aprotic polar solvent is preferred, and tetrahydrofuran is more preferred.

[0171] <<Stirring>>

[0172] The polymer composite may be formed by stirring a conjugated diene polymer, a free radical generator, and a reactant in a solvent at a temperature of at least 40°C but not higher than 200°C.

[0173] The temperature during stirring is preferably at least 40° C. but not higher than 200° C. At a temperature of at least 40° C., the reaction tends to proceed sufficiently, while at a temperature of not higher than 200° C., degradation of the conjugated diene polymer tends to be suppressed. The lower limit is more preferably at least 50° C., further more preferably at least 60° C., while the upper limit is more preferably not higher than 180° C., further more preferably not higher than 160° C., particularly preferably not higher than 140° C., and most preferably not higher than 120° C. When the temperature is within the above range, the beneficial effects tend to be better achieved.

[0174] The stirring method and stirring rate are not limited as long as the components in the solvent are miscible with each other.

[0175] The stirring time (reaction time) is not limited, but is preferably 0.5 hours or more, more preferably 1 hour or more, further more preferably 2 hours or more, and particularly preferably 4 hours or more. The upper limit is not limited, but is preferably 24 hours or less, more preferably 12 hours or less, and further more preferably 6 hours or less. When the stirring time is within the above range, the beneficial effect tends to be better achieved.

[0176] The amounts of the conjugated diene polymer, the radical generator, the reactant and the solvent used to produce the polymer composite are not limited but are preferably as described below. When the amount is within the range described below, the beneficial effects tend to be better achieved.

[0177] The amount of the reactant used is preferably 1 part by mass or more, more preferably 3 parts by mass or more, but is preferably 200 parts by mass or less, more preferably 120 parts by mass or less, based on 100 parts by mass of the conjugated diene polymer.

[0178] The amount of the radical generator used is preferably 0.001 mol or more, more preferably 0.01 mol or more, but is preferably 1.0 mol or less, more preferably 0.1 mol or less, based on 100 mol of the reactant.

[0179] The amount of the solvent used is not limited as long as the conjugated diene polymer, the free radical generator and the reactants are sufficiently miscible. For example, the amount of the solvent is about 18 times (mL / g) the amount of the monomer used.

[0180] The terminal of the temperature responsive polymer (eg, a group represented by any one of formulae (I) to (IV)) is described.

[0181] In the case of a polymer composite grafted with a temperature responsive polymer, one end of the temperature responsive polymer forms the main chain or a bond on the main chain, and the other end is usually a hydrogen atom but can be combined with a free radical generator such as azobisisobutyronitrile (AIBN).

[0182] The amount of the group whose hydrophilicity changes with temperature (the group formed by the reactant) is preferably 1% by mass or more, more preferably 5% by mass or more, further more preferably 10% by mass or more, particularly preferably 20% by mass or more, and most preferably 30% by mass or more, but is preferably 70% by mass or less, more preferably 60% by mass or less, and further more preferably 55% by mass or less, based on 100% by mass of the polymer composite material. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0183] Based on 100% by mass of the polymer composite material, the amount of the conjugated diene polymer is preferably 30% by mass or more, more preferably 40% by mass or more, and further more preferably 45% by mass or more, but is preferably 99% by mass or less, more preferably 95% by mass or less, further more preferably 90% by mass or less, particularly preferably 80% by mass or less, and most preferably 70% by mass or less. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0184] The total amount of the group whose hydrophilicity changes with temperature (the group formed by the reactant) and the conjugated diene polymer is preferably 80% by mass or more, more preferably 85% by mass or more, further more preferably 90% by mass or more, particularly preferably 95% by mass or more, most preferably 98% by mass or more, based on 100% by mass of the polymer composite material, and may be 100% by mass. When the total amount is within the above range, the beneficial effects tend to be better achieved.

[0185] Here, the amounts of the group (group formed from the reactant) that changes its hydrophilicity with temperature and the conjugated diene polymer in the polymer composite material are measured by NMR.

[0186] Since the group whose hydrophilicity changes with temperature in the polymer composite material is bonded to the conjugated diene polymer, the group whose hydrophilicity changes with temperature can be suppressed from dissolving in water or otherwise flowing out.

[0187] Here, merely mixing a conjugated diene polymer with a group that changes its hydrophilicity with temperature (temperature responsive polymer) does not result in a combination of the conjugated diene polymer with a group that changes its hydrophilicity with temperature, and thus does not provide a polymer composite. In addition, if the rubber composition is compounded with a temperature responsive polymer alone (rather than in the form of a polymer composite), the temperature responsive polymer may dissolve in water or otherwise flow out of the rubber composition, i.e., it may dissolve and disappear from the composition on rainy days. Therefore, it cannot be used for tread rubber that comes into contact with water on rainy days, and since it flows out, it cannot provide a beneficial effect.

[0188] The polymer composite material may be used as a rubber component for the rubber composition. The polymer composite material may include a single polymer composite material or a combination of two or more polymer composite materials.

[0189] The polymer composite is preferably a polymer composite in which a group showing a lower critical solution temperature (LCST) in water is bonded to BR or SBR, and more preferably a polymer composite in which a group showing a lower critical solution temperature (LCST) in water is bonded to SBR.

[0190] (Rubber component)

[0191] Since the polymer composite material includes the conjugated diene polymer, only the conjugated diene polymer in the polymer composite material may be used as the rubber component, but it is preferred that the conjugated diene polymer in the polymer composite material be used together with other rubber components.

[0192] Examples of such other rubber components include the above-mentioned diene rubbers. These may be used alone or in combination of two or more.

[0193] Here, the other rubber component and suitable embodiments thereof may be as described with respect to the conjugated diene polymer.

[0194] The amount of the polymer composite material in the rubber composition is preferably adjusted so that the amount of the group whose hydrophilicity changes with temperature (the group formed by the reactant) is preferably 1 part by mass or more, more preferably 3 parts by mass or more, further more preferably 5 parts by mass or more, particularly preferably 8 parts by mass or more, but is preferably 200 parts by mass or less, more preferably 180 parts by mass or less, further more preferably 160 parts by mass or less, particularly preferably 140 parts by mass or less, most preferably 120 parts by mass or less, further most preferably 100 parts by mass or less, further most preferably 80 parts by mass or less, particularly most preferably 50 parts by mass or less, and more particularly most preferably 30 parts by mass or less, relative to 100 parts by mass of the rubber component content. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0195] Based on 100% by mass of the rubber component content, the amount of SBR is preferably 20% by mass or more, more preferably 40% by mass or more, further more preferably 50% by mass or more, and can be 100% by mass, while the amount is preferably 90% by mass or less, more preferably 80% by mass or less. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0196] The amount of BR is preferably 5% by mass or more, more preferably 10% by mass or more, and further more preferably 20% by mass or more, based on 100% by mass of the rubber component content, and may be 100% by mass, while the amount is preferably 60% by mass or less, and more preferably 50% by mass or less. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0197] The total amount of SBR and BR is preferably 60% by mass or more, more preferably 80% by mass or more, further more preferably 90% by mass or more, based on 100% by mass of the rubber component content, and may be 100% by mass. When the total amount is within the above range, the beneficial effects tend to be better achieved.

[0198] Furthermore, as the rubber component, it is preferred that a multi-component copolymer containing a conjugated diene unit, a non-conjugated olefin unit and an aromatic vinyl unit is present. In this case, the advantageous effects tend to be more suitably achieved.

[0199] The conjugated diene unit in the multi-component copolymer is a structural unit derived from a conjugated diene compound. Examples of conjugated diene compounds include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene and 1,3-hexadiene. These can be used alone or in combination of two or more. 1,3-butadiene and isoprene are preferred, and 1,3-butadiene is more preferred.

[0200] The non-conjugated olefin unit in the multicomponent copolymer is a structural unit from a non-conjugated olefin. Examples of non-conjugated olefins include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene and 1-octene. These can be used alone or in combination of two or more. Preferred ethylene, propylene and 1-butene, more preferably ethylene.

[0201] The aromatic vinyl unit in the multi-component copolymer is a structural unit derived from an aromatic vinyl compound. Examples of aromatic vinyl compounds include styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene and 2,4,6-trimethylstyrene. These can be used alone or in combination of two or more. Styrene and α-methylstyrene are preferred, and styrene is more preferred.

[0202] For example, multi-component copolymers can be prepared as follows: copolymerization of conjugated diene compounds, non-conjugated olefins and aromatic vinyl compounds, or copolymerization of a combination of a conjugated diene compound and an aromatic vinyl compound or a combination of a conjugated diene compound, a non-conjugated olefin and an aromatic vinyl compound, and then hydrogenation of the copolymer to convert some conjugated diene units into non-conjugated olefin units. In other words, the multi-component copolymer can be a copolymer of a conjugated diene compound, a non-conjugated olefin and an aromatic vinyl compound, or can be a hydrogenated product (hydrogenated copolymer) of a copolymer of a conjugated diene compound and an aromatic vinyl compound or a copolymer of a conjugated diene compound, a non-conjugated olefin and an aromatic vinyl compound. These copolymers can be used alone or in combination of two or more. Among these, the multi-component copolymer is preferably a hydrogenated product of a copolymer of a conjugated diene compound and an aromatic vinyl compound, more preferably a hydrogenated styrene-butadiene copolymer (hydrogenated SBR).

[0203] The multicomponent copolymer may be prepared by any polymerization method (eg, random polymerization or block polymerization), preferably by random polymerization.

[0204] When the multi-component copolymer is a hydrogenated copolymer, the hydrogenation can be carried out by any method under any reaction conditions, including known methods and known conditions. Typically, the hydrogenation is carried out in the presence of a hydrogenation catalyst at 20 to 150° C. and an elevated hydrogen pressure of 0.1 to 10 MPa. Other methods and conditions related to the production process are also not limited, for example, the methods and conditions described in the above-mentioned WO2016 / 039005 can be used.

[0205] When the multi-component copolymer is a hydrogenated copolymer, the degree of hydrogenation is preferably 65 mol% or more, more preferably 70 mol% or more, and further more preferably 80 mol% or more, but preferably 95 mol% or less, more preferably 94.5 mol% or less, and further more preferably 94 mol% or less, based on 100 mol% of the entire conjugated diene units before hydrogenation. When the degree of hydrogenation is within the above range, the beneficial effects tend to be better achieved.

[0206] Here, the degree of hydrogenation can be measured by 1 It can be calculated from the reduction rate of the unsaturated bond signal in the H-NMR spectrum.

[0207] Based on 100 mol% of the overall structural units of the multi-component copolymer, the conjugated diene unit content is preferably 1.9 mol% or more, more preferably 2.4 mol% or more, and further more preferably 2.9 mol% or more, but is preferably 23.7 mol% or less, more preferably 16.9 mol% or less, and further more preferably 10.7 mol% or less. When the content is within the above range, the beneficial effects tend to be better achieved.

[0208] Based on 100 mol% of the overall structural units of the multi-component copolymer, the non-conjugated olefin unit content is preferably greater than 65 mol%, more preferably 70 mol% or more, and further more preferably 80 mol% or more, but preferably less than 95 mol%, more preferably 94.5 mol% or less, and further more preferably 94 mol% or less. When the content is within the above range, the beneficial effects tend to be better achieved.

[0209] The aromatic vinyl unit content is preferably 4 mol% or more, more preferably 8 mol% or more, but preferably 45 mol% or less, more preferably 40 mol% or less, further more preferably 35 mol% or less, particularly preferably 25 mol% or less, and most preferably 20 mol% or less, based on 100 mol% of the overall structural units of the multi-component copolymer. When the content is within the above range, the beneficial effects tend to be better achieved.

[0210] The content of each structural unit of the multi-component copolymer is measured by NMR.

[0211] The weight average molecular weight (Mw) of the multicomponent copolymer is preferably 100,000 or more, more preferably 150,000 or more, further more preferably 200,000 or more, particularly preferably 400,000 or more, but is preferably 2,000,000 or less, more preferably 1,500,000 or less, further more preferably 1,000,000 or less, particularly preferably 600,000 or less. When Mw is within the above range, the beneficial effects tend to be better achieved.

[0212] The amount of the multi-component copolymer is preferably 20% by mass or more, more preferably 40% by mass or more, and further more preferably 50% by mass or more, based on 100% by mass of the rubber component content, and may be 100% by mass, while the amount is preferably 90% by mass or less, and more preferably 80% by mass or less. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0213] (Silicon Dioxide)

[0214] The rubber composition preferably contains silica as a filler (reinforcing filler).

[0215] Any silica can be used, and examples include dry-process silica (anhydrous silicic acid) and wet-process silica (hydrous silicic acid). These can be used alone or in combination of two or more. Among these, wet-process silica is preferred because it has a large number of silanol groups.

[0216] Examples of commercially available silica include those available from Degussa AG, Rhodia AG, Tosoh Silicone Chemical Co., Ltd., Solvay K.K., Tokuyama Co., Ltd., and the like.

[0217] The nitrogen adsorption specific surface area of ​​silicon dioxide (N 2 SA) is preferably 50m 2 / g or more, more preferably 150m 2 / g or more, more preferably 160m 2 / g or more, particularly preferably 180m 2 / g or more, most preferably 200m 2 / g or more, and most preferably 220m 2 / g or more. N of silicon dioxide 2 There is no upper limit for SA, but 600m is preferred. 2 / g or less, more preferably 350m 2 / g or less, more preferably 260m 2 / g or less. 2 When SA is within the above range, beneficial effects tend to be more suitably achieved.

[0218] Here, N of silicon dioxide 2 SA is measured by the BET method according to ASTM D3037-93.

[0219] The cetyltrimethylammonium bromide adsorption specific surface area (CTAB specific surface area, CTAB) of silica is preferably 160 m 2 / g or more, more preferably 170m 2 / g or more, more preferably 180m 2 / g or more, even more preferably 200m 2 / g or more, particularly preferably 220m 2 / g or more, most preferably 250m 2 / g or more, but preferably 450m 2 / g or less, more preferably 400m 2 / g or less, more preferably 350m 2 / g or less, more preferably 330m 2 / g or less, particularly preferably 300m 2 When CTAB is within the above range, beneficial effects tend to be more suitably achieved.

[0220] Here, the CTAB specific surface area of ​​silica is measured in accordance with JIS K 6217-3 (2001).

[0221] The amount of silica is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, further more preferably 40 parts by mass or more, particularly preferably 60 parts by mass or more, and most preferably 80 parts by mass or more, but is preferably 200 parts by mass or less, more preferably 180 parts by mass or less, further more preferably 150 parts by mass or less, particularly preferably 120 parts by mass or less, and most preferably 100 parts by mass or less relative to 100 parts by mass of the rubber component content. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0222] (Silane coupling agent)

[0223] When the rubber composition contains silica, it preferably contains both silica and a silane coupling agent.

[0224] Any silane coupling agent may be used. Examples include sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(4-trimethoxysilylbutyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(2-triethoxysilylethyl ...3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-triethoxysil sulfide, bis(3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-trimethoxysilylethyl) disulfide, bis(4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide sulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based silane coupling agents, such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, NXT and NXT-Z (both can be purchased from Momentive); vinyl-based silane coupling agents, such as vinyltriethoxysilane and vinyltrimethoxysilane; amino ... Alkyl coupling agents such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chlorine silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. These can be used alone or in combination of two or more. Among these, sulfide silane coupling agents are preferred.

[0225] Examples of commercially available silane coupling agents include those available from Degussa Corporation, Momentive Corporation, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., AZmax Co., Ltd., Dow Corning Toray Industries, Ltd., and the like.

[0226] If a silane coupling agent is present, the amount of the silane coupling agent is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and further more preferably 2 parts by mass or more relative to 100 parts by mass of the silica content. In addition, the amount is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and further more preferably 12 parts by mass or less. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0227] (Carbon Black)

[0228] The rubber composition preferably contains carbon black as a filler (reinforcing filler). In this case, the advantageous effects tend to be more suitably achieved.

[0229] Examples of carbon black include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. These may be used alone or in combination of two or more.

[0230] Nitrogen adsorption specific surface area of ​​carbon black (N 2 SA) is preferably 5m 2 / g or more, more preferably 30m 2 / g or more, more preferably 60m 2 / g or more, particularly preferably 90m 2 / g or more, most preferably 120m 2 / g or more. In addition, N 2 SA is preferably 300m 2 / g or less, more preferably 200m 2 / g or less, more preferably 180m 2 / g or less. 2 When SA is within the above range, the beneficial effects tend to be better achieved.

[0231] Here, the nitrogen adsorption specific surface area of ​​carbon black can be determined in accordance with JIS K 6217-2:2001.

[0232] The dibutyl phthalate oil absorption (DBP) of carbon black is preferably 5 ml / 100 g or more, more preferably 70 ml / 100 g or more, and further more preferably 90 ml / 100 g or more. In addition, DBP is preferably 300 ml / 100 g or less, more preferably 200 ml / 100 g or less, further more preferably 160 ml / 100 g or less, and particularly preferably 140 ml / 100 g or less. When DBP is within the above range, the beneficial effects tend to be better achieved.

[0233] Here, the DBP of carbon black can be measured according to JIS K 6217-4:2001.

[0234] Examples of commercially available carbon black include those available from Asahi Carbon Co., Ltd., Cabot (Japan) Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin Nichika Carbon Co., Ltd., Columbia Carbon Co., Ltd., and the like.

[0235] The amount of carbon black is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, further more preferably 3 parts by mass or more, particularly preferably 5 parts by mass or more, but is preferably 120 parts by mass or less, more preferably 80 parts by mass or less, further more preferably 50 parts by mass or less, particularly preferably 20 parts by mass or less, relative to 100 parts by mass of the rubber component content. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0236] (sulfur)

[0237] The rubber composition preferably contains sulfur.

[0238] Examples of sulfur include those commonly used in the rubber industry, such as powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur. These may be used alone or in combination of two or more.

[0239] Examples of commercially available sulfur include those available from Tsurumi Chemical Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexsys Corporation, Nippon Senryu Industry Co., Ltd., Hosoi Chemical Co., Ltd., and the like.

[0240] The amount of sulfur is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and further more preferably 1 part by mass or more, relative to 100 parts by mass of the rubber component content. In addition, the amount is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, further more preferably 8 parts by mass or less, and particularly preferably 5 parts by mass or less. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0241] (Vulcanization accelerator)

[0242] The rubber composition preferably contains a vulcanization accelerator.

[0243] Examples of the vulcanization accelerator include: thiazole vulcanization accelerators such as 2-mercaptobenzothiazole and di-2-benzothiazolyl disulfide; thiuram vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD) and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide vulcanization accelerators such as N-cyclohexyl-2-benzothiazolyl sulfenamide, N-tert-butyl-2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolylsulfenamide and N,N′-diisopropyl-2-benzothiazolylsulfenamide; and guanidine-based vulcanization accelerators, such as diphenylguanidine, di-o-tolylguanidine and o-tolylbiguanide; thiourea-based vulcanization accelerators; dithiocarbamic acid-based vulcanization accelerators; aldehydeamine-based or aldehydeamine-based vulcanization accelerators; imidazoline-based vulcanization accelerators; and xanthate-based vulcanization accelerators. These can be used alone or in combination of two or more. Among these, sulfenamide-based vulcanization accelerators or guanidine-based vulcanization accelerators are preferred.

[0244] Examples of commercially available vulcanization accelerators include those available from Kawaguchi Chemical Industry Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Rhein Chemie AG, and the like.

[0245] The amount of the vulcanization accelerator is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and further more preferably 1 part by mass or more relative to 100 parts by mass of the rubber component content. In addition, the amount is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, further more preferably 8 parts by mass or less, and particularly preferably 5 parts by mass or less. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0246] (Stearic Acid)

[0247] The rubber composition preferably contains stearic acid.

[0248] Conventionally known stearic acids can be used, including, for example, those available from NOF Corporation, Kao Corporation, Fujifilm Co., Ltd., Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., and the like.

[0249] The amount of stearic acid is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and further more preferably 1 part by mass or more relative to 100 parts by mass of the rubber component content. In addition, the amount is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, further more preferably 8 parts by mass or less, and particularly preferably 5 parts by mass or less. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0250] (Zinc Oxide)

[0251] The rubber composition may include zinc oxide.

[0252] Conventionally known zinc oxide can be used, including, for example, those available from Mitsui Mining and Smelting Co., Ltd., Toho Lead Co., Ltd., Hakusui Tech Co., Ltd., Shodo Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., and the like.

[0253] The amount of zinc oxide is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and further more preferably 1 part by mass or more relative to 100 parts by mass of the rubber component content. In addition, the amount is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, further more preferably 8 parts by mass or less, and particularly preferably 5 parts by mass or less. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0254] (Antioxidant)

[0255] The rubber composition may contain an antioxidant.

[0256] Examples of antioxidants include naphthylamine antioxidants such as phenyl-α-naphthylamine; diphenylamine antioxidants such as octylated diphenylamine and 4,4′-bis(α,α′-dimethylbenzyl)diphenylamine; p-phenylenediamine antioxidants such as N-isopropyl-N′-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine and N,N′-di-2-naphthyl-p-phenylenediamine; quinoline antioxidants such as polymerized 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol antioxidants such as 2,6-di-tert-butyl-4-methylphenol and styrenated phenol; and bisphenol antioxidants, triphenol antioxidants or polyphenol antioxidants such as tetrakis[methylene-3-(3′,5′-di-tert-butyl-4′-hydroxyphenyl)propionate]methane. These may be used alone or in combination of two or more. Among these, p-phenylenediamine antioxidants and quinoline antioxidants are preferred.

[0257] Examples of commercially available antioxidants include those available from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., Flex Corporation, and the like.

[0258] The amount of the antioxidant is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and further more preferably 1 part by mass or more, relative to 100 parts by mass of the rubber component content. In addition, the amount is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, further more preferably 8 parts by mass or less, and particularly preferably 5 parts by mass or less. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0259] (wax)

[0260] The rubber composition may contain wax.

[0261] Any wax may be used, examples of which include: petroleum waxes such as paraffin wax and microcrystalline wax; naturally occurring waxes such as plant wax and animal wax; and synthetic waxes such as polymers of ethylene, propylene or other similar monomers. These may be used alone or in combination of two or more.

[0262] Examples of commercially available waxes include those available from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Seiko Chemical Co., Ltd., and the like.

[0263] The amount of the wax is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and further more preferably 1 part by mass or more relative to 100 parts by mass of the rubber component content. In addition, the amount is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, further more preferably 8 parts by mass or less, and particularly preferably 5 parts by mass or less. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0264] (Plasticizer)

[0265] The rubber composition may contain a plasticizer.

[0266] Herein, the term "plasticizer" refers to a material that imparts plasticity to rubber, and conceptually includes a liquid plasticizer (a plasticizer that is liquid at 25°C) and a solid plasticizer (a plasticizer that is solid at 25°C). Specifically, it is a component that can be extracted from the composition with acetone. Such plasticizers can be used alone or in combination of two or more.

[0267] Specific examples of plasticizers include oils, ester plasticizers, liquid polymers and resin components (also collectively referred to as oils, etc.). These can be used alone or in combination of two or more. The term "liquid polymer" refers to a polymer that is liquid at room temperature (25°C). The term "resin component" refers to a resin that is liquid at room temperature (25°C) or a resin that is solid at room temperature (25°C). In order to more appropriately achieve the beneficial effects, among these, oils, liquid polymers and resin components are preferred, liquid polymers or resin components are more preferred, and resin components are further more preferred.

[0268] The amount of the plasticizer is preferably 0.1 parts by mass or more, more preferably 5 parts by mass or more, further more preferably 10 parts by mass or more, and particularly preferably 20 parts by mass or more relative to 100 parts by mass of the rubber component content. In addition, the amount is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, further more preferably 60 parts by mass or less, and particularly preferably 40 parts by mass or less. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0269] Any oil can be used, examples include conventional oils, including: process oils, such as paraffinic process oils, aromatic process oils, and cycloparaffinic process oils; low polycyclic aromatic (PCA) process oils, such as TDAE and MES; vegetable oils; and mixtures of the above oils. These can be used alone or in combination of two or more. Among these, aromatic process oils are preferred. Specific examples of aromatic process oils include Diana process oil AH series produced by Idemitsu Kosan Co., Ltd.

[0270] Examples of commercially available oils include those available from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Nippon Energy Co., Ltd., Olisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Refining Co., Ltd., Showa Shell Sekiyu Co., Ltd., Fuji Kosan Co., Ltd., and the like.

[0271] The amount of oil is preferably 0.1 parts by mass or more, more preferably 5 parts by mass or more, further more preferably 10 parts by mass or more, and particularly preferably 20 parts by mass or more relative to 100 parts by mass of the rubber component content. In addition, the amount is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, further more preferably 60 parts by mass or less, and particularly preferably 40 parts by mass or less. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0272] Examples of ester plasticizers include: the above-mentioned vegetable oils; synthetic plasticizers and processed vegetable oils, such as glycerol fatty acid monoesters, glycerol fatty acid diesters, and glycerol fatty acid triesters; and phosphoric acid esters (e.g., phosphoric acid ester plasticizers and mixtures thereof). These can be used alone or in combination of two or more.

[0273] Suitable examples of the ester plasticizer include fatty acid esters represented by the following formula.

[0274]

[0275] In the formula, R 11 represents a C1-C8 straight or branched alkyl group, a C1-C8 straight or branched alkenyl group, or a C2-C6 straight or branched alkyl group substituted with 1 to 5 hydroxyl groups; R 12 It represents a C11-C21 alkyl or alkenyl group.

[0276] R 11 Examples of R include methyl, ethyl, 2-ethylhexyl, isopropyl and octyl, and groups obtained by substituting these groups with 1 to 5 hydroxyl groups. 12 Examples include straight-chain or branched alkyl or alkenyl groups such as lauryl, myristyl, palmityl, stearyl and oleyl.

[0277] Examples of fatty acid esters include alkyl oleates, alkyl stearates, alkyl linoleates, and alkyl palmitates. Among these, alkyl oleates (e.g., methyl oleate, ethyl oleate, oleic acid-2-ethylhexyl ester, isopropyl oleate, octyl oleate) are preferred. In this case, the amount of the alkyl oleate is preferably 80% by mass or more based on 100% by mass of the fatty acid ester.

[0278] Other examples of fatty acid ester include fatty acid monoester or fatty acid diester formed by fatty acid (e.g. oleic acid, stearic acid, linoleic acid, palmitic acid) and alcohol (e.g. ethylene glycol, glycerine, trimethylolpropane, pentaerythritol, erythritol, xylitol, sorbitol, dulcitol, mannitol, inositol). Among these, oleic acid monoester is preferred. In this case, the total amount of fatty acid monoester and fatty acid diester of 100 mass % is taken as a benchmark, and the amount of oleic acid monoester is preferably more than 80 mass %.

[0279] Phosphoric acid esters can be suitably used as the ester plasticizer.

[0280] Preferred phosphoric acid esters include C12-C30 compounds, wherein C12-C30 trialkyl phosphates are suitable. Here, the carbon number of trialkyl phosphates refers to the total number of carbon atoms in three alkyl groups. The three alkyl groups can be the same group or different groups. Examples of alkyl groups include straight or branched chain alkyl groups, which may contain heteroatoms (e.g., oxygen atoms) or may be substituted by halogen atoms (e.g., fluorine, chlorine, bromine or iodine).

[0281] Other examples of phosphoric acid esters include known phosphoric acid ester plasticizers, such as monoesters, diesters or triesters of phosphoric acid and C1-C12 monohydric alcohols or (poly)oxyalkylene adducts thereof; and compounds obtained by substituting one or two alkyl groups of the above trialkyl phosphates with a phenyl group. Specific examples include tri(2-ethylhexyl)phosphate, trimethylphosphate, triethylphosphate, tributylphosphate, trioctylphosphate, triphenylphosphate, tricresylphosphate, trixyltolylphosphate, cresyldiphenylphosphate, 2-ethylhexyldiphenylphosphate and tri(2-butoxyethyl)phosphate.

[0282] Examples of liquid polymers include liquid rubber and liquid farnesene polymers. These can be used alone or in combination of two or more. In order to more appropriately achieve beneficial effects, among these, liquid farnesene polymers are preferred.

[0283] Examples of liquid rubbers include liquid diene rubbers that can be extracted with acetone. Specific examples include: liquid styrene-butadiene copolymers (liquid SBR), liquid polybutadiene polymers (liquid BR), liquid polyisoprene polymers (liquid IR), liquid styrene-isoprene copolymers (liquid SIR), liquid styrene-butadiene-styrene block copolymers (liquid SBS block polymers) and liquid styrene-isoprene-styrene block copolymers (liquid SIS block polymers), all of which are liquid at 25°C. The chain ends or main chains of these rubbers can be modified with polar groups. Hydrogenated products of these rubbers can also be used. These can be used alone or in combination of two or more.

[0284] The term "liquid farnesene polymer" refers to a polymer produced by polymerizing farnesene and contains a farnesene-based structural unit. Farnesene has isomers such as α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecatetraene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecatriene). (E)-β-farnesene having the following structure is preferred.

[0285]

[0286] The liquid farnesene polymer may be a homopolymer of farnesene (farnesene homopolymer) or a copolymer of farnesene and a vinyl monomer (farnesene-vinyl monomer copolymer). These may be used alone or in combination of two or more. Among these, copolymers of farnesene and a vinyl monomer are preferred.

[0287] Examples of vinyl monomers include aromatic vinyl compounds such as styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-tert-butylstyrene, 5-tert-butyl-2-methylstyrene, vinylethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, tert-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethylether, N,N-dimethylaminoethylstyrene, N,N-dimethylaminomethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-tert-butylstyrene, 3-tert-butylstyrene, 4-tert-butylstyrene, vinylxylene, vinylnaphthalene, vinyltoluene, vinylpyridine, diphenylethylene and diphenylethylene containing tertiary amine groups, and conjugated diene compounds such as butadiene and isoprene. These can be used alone or in combination of two or more. Among these, butadiene is preferred. In other words, among the farnesene-vinyl monomer copolymers, a copolymer of farnesene and butadiene (farnesene-butadiene copolymer) is preferred.

[0288] The copolymerization ratio of farnesene and vinyl monomer (farnesene / vinyl monomer) of the farnesene-vinyl monomer copolymer is preferably 40 / 60 to 90 / 10 (by mass).

[0289] Liquid farnesene polymers having a weight average molecular weight (Mw) of 3,000 to 300,000 can be suitably used. The Mw of the liquid farnesene polymer is preferably 8,000 or more, more preferably 10,000 or more, but preferably 100,000 or less, more preferably 60,000 or less, and further more preferably 50,000 or less. When the Mw is within the above range, the beneficial effects tend to be more suitably achieved.

[0290] The amount of the liquid polymer is preferably 0.1 parts by mass or more, more preferably 5 parts by mass or more, further more preferably 10 parts by mass or more, and particularly preferably 20 parts by mass or more relative to 100 parts by mass of the rubber component content. In addition, the amount is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, further more preferably 60 parts by mass or less, and particularly preferably 40 parts by mass or less. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0291] The amount of the resin component (the total amount of the resin that is liquid at room temperature (25° C.) and the resin that is solid at room temperature (25° C.)) is preferably 5 parts by mass or more, more preferably 8 parts by mass or more, but is preferably 60 parts by mass or less, more preferably 40 parts by mass or less, and further preferably 20 parts by mass or less. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0292] Examples of resins that are liquid at room temperature (25°C) as resin components include liquid resins. Liquid resins may be those having a softening point not higher than room temperature and being liquid at room temperature. Examples of liquid resins include: terpene resins (including terpene phenol resins and aromatic modified terpene resins), rosin resins, styrene resins, C5 resins, C9 resins, C5 / C9 resins, dicyclopentadiene (DCPD) resins, coumarone-indene resins (including resins based on coumarone or indene alone), phenolic resins, olefin resins, polyurethane resins, and acrylic resins. Hydrogenated products of the above resins may also be used. These may be used alone or in combination of two or more.

[0293] The amount of the liquid resin in the rubber composition is preferably 5 parts by mass or more, more preferably 8 parts by mass or more, but is preferably 60 parts by mass or less, more preferably 40 parts by mass or less, and further preferably 20 parts by mass or less, relative to 100 parts by mass of the rubber component content. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0294] Examples of resins that are solid at room temperature (25° C.) as the resin component (hereinafter also referred to as “solid resins”) include aromatic vinyl polymers, coumarone-indene resins, coumarone resins, indene resins, phenolic resins, rosin resins, petroleum resins, terpene resins, and acrylic resins, all of which are solid at room temperature (25° C.). The resins may also be hydrogenated. These may be used alone or in combination of two or more. In order to more appropriately achieve the beneficial effects, among these, aromatic vinyl polymers, terpene resins, petroleum resins, and hydrogenated products thereof are preferred, and aromatic vinyl polymers are more preferred.

[0295] The softening point of the solid resin is preferably 60° C. or higher, more preferably 70° C. or higher, and further more preferably 80° C. or higher. The upper limit is preferably 160° C. or lower, more preferably 130° C. or lower, and further more preferably 115° C. or lower. When the softening point is within the above range, the beneficial effects tend to be more suitably achieved.

[0296] Here, the softening point of the resin component is measured using a ring and ball softening point measuring device in accordance with the provisions of JIS K 6220-1:2001, and is defined as the temperature when a ball falls.

[0297] Aromatic vinyl polymers refer to polymers containing aromatic vinyl monomers as structural units. Examples include resins produced by polymerizing α-methylstyrene and / or styrene. Specific examples include: styrene homopolymers (styrene resins), α-methylstyrene homopolymers (α-methylstyrene resins), copolymers of α-methylstyrene and styrene, and copolymers of styrene and other monomers. Among these, copolymers of α-methylstyrene and styrene are preferred.

[0298] The coumarone-indene resin refers to a resin containing coumarone and indene as the main monomer components forming the resin skeleton (main chain). In addition to coumarone and indene, examples of monomer components that may be contained in the skeleton include styrene, α-methylstyrene, methylindene and vinyltoluene. Here, the amount of the coumarone-indene resin is preferably 1 to 200 parts by mass relative to 100 parts by mass of the rubber component content.

[0299] The coumarone resin refers to a resin containing coumarone as a main monomer component forming the resin skeleton (main chain).

[0300] Indene resin refers to a resin containing indene as a main monomer component forming the resin skeleton (main chain).

[0301] Examples of phenolic resins include known polymers produced by reacting phenol with aldehydes (such as formaldehyde, acetaldehyde or furfural) using an acid or base catalyst. Among these, those produced by reacting using an acid catalyst, such as a novolac type phenolic resin, are preferred.

[0302] Examples of the rosin resin include rosin-based resins, represented by natural rosin, polymerized rosin, modified rosin, esterified compounds thereof, and hydrogenated products thereof. Here, the amount of the rosin resin is preferably 1 to 200 parts by mass relative to 100 parts by mass of the rubber component content.

[0303] Examples of petroleum resins include C5-based resins, C9-based resins, C5 / C9-based resins, dicyclopentadiene (DCPD) resins, and hydrogenated products of the foregoing resins. Among these, DCPD resins or hydrogenated DCPD resins are preferred.

[0304] Terpene resins refer to polymers containing terpene as a structural unit. Examples include polyterpene resins produced by polymerizing terpene compounds, and aromatic modified terpene resins produced by polymerizing terpene compounds and aromatic compounds. Hydrogenated products of these resins may also be used.

[0305] Polyterpene resin refers to a resin formed by the polymerization of terpene compounds. 5 H 8 ) n A hydrocarbon of a composition represented by or an oxygen-containing derivative thereof, each of which has a terpene backbone and is classified as a monoterpene (C 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32 ) or other terpenes. Examples of terpene compounds include α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0306] Examples of polyterpene resins include resins made from the above-mentioned terpene compounds, such as pinene resins, limonene resins, dipentene resins, and pinene-limonene resins. Among these resins, pinene resins are preferred. Pinene resins generally have two isomers, namely α-pinene and β-pinene, and can be divided into β-pinene resins mainly containing β-pinene and α-pinene resins mainly containing α-pinene according to the ratio of each component.

[0307] Examples of aromatic modified terpene resins include terpene-phenol resins made from the above-mentioned terpene compounds and phenolic compounds, and terpene-styrene resins made from the above-mentioned terpene compounds and styrene compounds. Terpene-phenol-styrene resins made from terpene compounds, phenolic compounds and styrene compounds can also be used. Here, examples of phenolic compounds include phenol, bisphenol A, cresol and xylenol, and examples of styrene compounds include styrene and α-methylstyrene.

[0308] Acrylic resin refers to a polymer containing an acrylic monomer as a structural unit. Examples include styrene acrylic resins, such as those produced by copolymerizing an aromatic vinyl monomer component and an acrylic monomer component, which contain a carboxyl group. Among these, solvent-free carboxyl-containing styrene acrylic resins are suitable.

[0309] The solvent-free carboxyl-containing styrene acrylic resin may be a (meth) acrylic resin (polymer) synthesized by high temperature continuous polymerization (e.g., high temperature continuous bulk polymerization described in U.S. Pat. No. 4,414,370, JP S59-6207A, JP H5-58005B, JP H1-313522A, U.S. Pat. No. 5,010,166, and the annual research report TREND 2000, Vol. 3, pp. 42-45, published by Toagosei Co., Ltd.) without or with a very small amount of auxiliary raw materials (e.g., polymerization initiator, chain transfer agent, and organic solvent). As used herein, the term "(meth) acrylic acid" refers to methacrylic acid and acrylic acid.

[0310] Examples of the acrylic monomer component of the acrylic resin include (meth)acrylic acid and (meth)acrylic acid derivatives, such as (meth)acrylic acid esters (e.g., alkyl esters, aryl esters, and aralkyl esters, such as 2-ethylhexyl acrylate), (meth)acrylamide, and (meth)acrylamide derivatives. Here, the term "(meth)acrylic acid" is a general term for acrylic acid and methacrylic acid.

[0311] Examples of the aromatic vinyl monomer component of the acrylic resin include aromatic vinyl monomers such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene.

[0312] In addition to (meth)acrylic acid or a (meth)acrylic acid derivative and the aromatic vinyl monomer, other monomer components may be used as the monomer components of the acrylic resin.

[0313] The amount of the solid resin is preferably 5 parts by mass or more, more preferably 8 parts by mass or more, but is preferably 60 parts by mass or less, more preferably 40 parts by mass or less, and further preferably 20 parts by mass or less relative to 100 parts by mass of the rubber component content. When the amount is within the above range, the beneficial effects tend to be better achieved.

[0314] Examples of commercially available plasticizers include those available from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF Corporation, Arizona Chemical Company, Nippon Paint Chemical Co., Ltd., Nippon Shokubai Co., Ltd., JXTG Nippon Oil & Energy Co., Ltd., Arakawa Chemical Industries, Ltd., Taoka Chemical Industries, Ltd., Novares-Rutgers, Sartomer, Kuraray Co., Ltd., and the like.

[0315] In addition to the above components, the rubber composition may contain additives commonly used in the tire industry, such as vulcanizing agents other than sulfur (e.g., organic crosslinking agents, organic peroxides), calcium carbonate, mica (e.g., sericite), aluminum hydroxide, magnesium oxide, magnesium hydroxide, clay, talc, aluminum oxide, and titanium oxide. The amount of each of these components is preferably 0.1 parts by mass or more, but preferably 200 parts by mass or less, relative to 100 parts by mass of the polymer component (preferably rubber component) content.

[0316] Examples of organic peroxides include benzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, tert-butyl cumyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3 and 1,3-bis(tert-butylperoxypropyl)benzene. These may be used alone or in combination of two or more.

[0317] For example, the rubber composition can be prepared by kneading the components using a rubber kneading device such as an open roll mill or a Banbury mixer, and then vulcanizing the kneaded mixture.

[0318] The kneading conditions are as follows. In the basic kneading step of kneading additives other than the crosslinking agent (vulcanizing agent) and the vulcanization accelerator, the kneading temperature is generally 100 to 180° C., preferably 120 to 170° C. In the final kneading step of kneading the vulcanizing agent and the vulcanization accelerator, the kneading temperature is generally below 120° C., preferably 80 to 110° C. Then, the rubber composition obtained after kneading the vulcanizing agent and the vulcanization accelerator is generally vulcanized by, for example, press vulcanization. The vulcanization temperature is generally 140 to 190° C., preferably 150 to 185° C.

[0319] Although the rubber composition is used for a tread (track tread), it can also be used for tire components such as sidewalls, base treads, undertreads, clinchers, bead apex rubbers, breaker cushion rubbers, carcass cord topping rubbers, insulation layers, bead chafers and inner liners, and side reinforcing layers of run-flat tires.

[0320] (tire)

[0321] The tire of the present invention can be produced from the rubber composition by conventional methods. Specifically, the tire can be produced as follows: an unvulcanized rubber composition (which contains various additives as required) is extruded into the shape of a tread (tread surface), then molded and assembled with other tire components in a conventional manner on a tire molding machine to produce an unvulcanized tire, and then the unvulcanized tire is heated and pressurized in a vulcanizer.

[0322] Tire can be any type of tire, including pneumatic tire, solid tire and airless tire. Among these, pneumatic tire is preferred.

[0323] The tire can be suitably used as a tire for a passenger car, a tire for a large passenger car, a tire for a large SUV, a tire for a truck and a bus, or a tire for a two-wheeled vehicle, or as a racing tire, a winter tire (studless tire, snow tire, studded tire), an all-season tire, a run-flat tire, an aircraft tire, a mining tire, etc. In particular, the tire can be more suitably used as a tire for a passenger car.

[0324] The tire has a tread portion having at least one main groove extending continuously in the tire circumferential direction, and the S of the tread portion 50 / S 0 The ratio is greater than 1, where S 0 Indicates the proportion of sea in the tread contact area of ​​a new tire (%), S 50 It indicates the sea ratio (%) when the tread portion is worn until the main groove depth reaches 50% of the main groove depth of a new tire.

[0325] In the tire, preferably, at least one main groove has a groove wall, the groove wall is provided with a recessed portion, the recessed portion is recessed outward in the groove width direction from the groove edge appearing on the tread surface of the tread portion, the total recessed amount of the main groove is 0.10 to 0.90 times the groove width, and the groove width is the length between the groove edges of the main groove.

[0326] In the tire, preferably, the first groove wall (a groove wall of the main groove) is provided with at least one first recess, the first recess being recessed outwardly in the groove width direction from the groove edge appearing on the tread surface of the tread portion, and gradually reducing the recess amount from the groove edge from the deepest part recessed outwardly in the groove width direction toward both sides of the tire circumference.

[0327] In the tire, the first recessed portion is preferably provided on the groove bottom side of the groove wall.

[0328] In the tire, the first recessed portion preferably has an arc-shaped contour portion when viewed in a cross section taken along the tread surface and passing through the deepest portion.

[0329] In the tire, the first recessed portion preferably gradually decreases in amount from the deepest portion toward the outer side in the tire radial direction when viewed in a groove cross section passing through the deepest portion.

[0330] In the tire, the amount of depression at the deepest portion is preferably 0.10 to 0.50 times the groove width, where the groove width is the length between the groove edges of the main groove.

[0331] In the tire, the first groove wall is preferably provided with at least one second recessed portion that is recessed outward from the groove edge in the groove width direction, and the recessed amount of the second recessed portion from the groove edge is constant in the tire circumferential direction.

[0332] In the tire, the maximum recessed amount of the second recessed portion is preferably smaller than the recessed amount of the deepest portion of the first recessed portion.

[0333] In the first groove wall of the tire, the first recessed portions and the second recessed portions are preferably arranged alternately in the tire circumferential direction.

[0334] In the tire, the second groove wall (the other groove wall of the main groove) is preferably provided with at least one first recessed portion as described above.

[0335] In the tire, preferably, each of the first groove wall and the second groove wall is provided with a plurality of the first recessed portions as described above, and the first recessed portions in the first groove wall and the first recessed portions in the second groove wall are alternately provided in the tire circumferential direction.

[0336] A procedure for producing a tire according to one embodiment of the present invention will be described in detail below. However, the following description is used as an example to describe the present invention and is not intended to limit the technical scope of the present invention thereto.

[0337] [Tread pattern]

[0338] Figure 1 An exemplary but non-limiting tire according to one embodiment of the present invention is shown in FIG. Figure 1 A cross-sectional view of a tread portion 2 of a tire 1 is shown. Here, Figure 1 is a meridian cross section including the rotation axis of the tire 1 in a normal state. The tire 1 of the present invention can be suitably used as a pneumatic tire for a passenger car. However, the tire 1 is not limited to this embodiment, and can be used as a heavy-duty tire, for example.

[0339] Unless otherwise specified, the dimensions and angles of the various components of the tire in the present invention are measured when the tire is mounted on a regular rim and inflated to a regular internal pressure. During the measurement, no load is applied to the tire. In this article, the term "regular rim" refers to the rim specified for each tire by the standard in the standard system (including the standard on which the tire is provided), for example, it can be the standard rim in JATMA, the "design rim" in TRA, or the "measurement rim" in ETRTO. In this article, the term "regular internal pressure" refers to the air pressure specified by the standard for each tire, which can be the maximum air pressure in JATMA, the maximum value in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in TRA, or the "inflation pressure" in ETRTO.

[0340] like Figure 1 As shown, the tread portion 2 has at least one main groove 3 extending continuously in the tire circumferential direction. In the embodiment of the present invention, the tire has four main grooves 3, which are arranged adjacent to each other in the tire axial direction between the tire equator C and each tread end Te, but the present invention is not limited to this embodiment.

[0341] The tread end Te refers to the axially outermost contact position of the tire 1 determined when the tire 1 with a normal load applied in a normal state is brought into contact with a flat surface at a camber angle of 0 degrees.

[0342] The term "normal load" refers to the load specified by the standard for each tire, which may be the maximum load capacity in JATMA, the maximum value shown in the table "Tire load limits at various cold inflation pressures" in TRA, or the "Load capacity" in ETRTO.

[0343] The groove width W1 of each main groove 3 is preferably, for example, 3.0 to 6.0% of the tread width TW. In this document, unless otherwise specified, the groove width of the main groove refers to the length between the groove edges appearing on the tread surface of the tread portion 2. The tread width TW refers to the distance in the tire axial direction from one tread end Te to the other tread end Te in a normal state. When the tire is a pneumatic tire for a passenger car, the groove depth of each main groove 3 is preferably, for example, 5 to 10 mm.

[0344] In the tire, at least one main groove 3 has a groove wall provided with a recessed portion that is recessed outward in the groove width direction from a groove edge 6 that appears on the tread surface of the tread portion 2. The tread pattern of the tire is not limited as long as it has a sea ratio change (S 50 / S 0 ) The groove shape is within the range shown in the previous text.

[0345] Figure 2An enlarged plan view of the main groove 3 according to the present invention is shown. Figure 2 , the groove edge 6 of the main groove 3 is indicated by a solid line, and the contour 7 of the groove wall when the tread portion 2 is viewed in a planar perspective is indicated by a dotted line. In addition, the colored portion indicates a recessed area between each groove edge 6 of the main groove 3 and each groove wall contour 7.

[0346] Figure 3 Shows Figure 2 AA cross-sectional view of the main groove 3 shown in FIG. Figure 3 As shown, the main groove 3 has a recess 9 in the groove wall on both sides, and the recess amount in the recess 9 is constant in the tire circumferential direction. For example, the recess 9 includes a plane 15 between the deepest part 13 and the groove edge 6, but it is not limited to this embodiment.

[0347] In order to ensure the groove volume of the main groove 3, the depression amounts c1 and c2 from the groove edge 6 at the deepest part 13 are each independently preferably 0.05 to 0.45 times, more preferably 0.07 to 0.40 times, and further more preferably 0.10 to 0.35 times the groove width W1, and the groove width W1 is the length between the groove edges of the main groove 3.

[0348] Figure 4 An enlarged plan view of another main groove 3 according to the present invention is shown. Figure 4 As shown, the first groove wall 10 (one groove wall of the main groove 3) is provided with at least one first recessed portion 11. The first groove wall 10 according to the embodiment of the present invention is provided with a plurality of first recessed portions 11.

[0349] exist Figure 4 , the groove edge 6 of the main groove 3 is indicated by a solid line, and the contour 7 of the groove wall when the tread portion 2 is viewed from a planar perspective is indicated by a dotted line. In addition, the colored portion indicates a recessed area between each groove edge 6 of the main groove 3 and the contour 7 of each groove wall. Each first recess 11 is recessed outward in the groove width direction from the groove edge 6 appearing on the tread surface of the tread portion 2. In the first recess 11, as the tread portion 2 wears, the opening area of ​​the main groove 3 increases. Therefore, it is possible to exhibit more excellent steering stability over a long period of time.

[0350] Each first recess 11 gradually decreases the amount of depression from the groove edge 6 toward both sides in the tire circumferential direction from the deepest portion 13 most depressed outward in the groove width direction. This can ensure the rigidity of the land portion defined by the main groove 3 on both sides of the deepest portion 13 relative to the tire circumferential direction, so that the groove edge side portion 8 ( Figure 1 ) is deformed toward the groove center side of the main groove 3. In addition, the first recessed portion 11 can smoothly change the rigidity of the land portion in the tire circumferential direction to suppress local deformation of the groove edge side portion 8. Therefore, more excellent steering stability can be obtained.

[0351] Generally speaking, during wet driving, the main groove extending continuously in the circumferential direction of the tire drains water backwards against the traveling direction of the tire, but when there is a lot of water on the road, the groove tends to push some water forward in the traveling direction of the tire. Due to the first recess 11 as described above, the main groove 3 of the present invention can push some water forward in the traveling direction of the tire, and push some water outward in the axial direction of the tire, and further can suppress the pushed water from entering between the tread portion 2 and the road. In addition, since the groove area increases as wear progresses, the reduction in groove volume associated with the progression of wear can be delayed compared to conventional grooves.

[0352] In each first recess 11, the arcuate contour portion 7 preferably has a curvature that gradually increases inward in the tire radial direction (when viewed in a cross section taken along the tread surface of the tread portion 2). Such a first recess 11 can ensure a large groove volume of the main groove 3 while suppressing deformation of the groove edge side portion 8.

[0353] In the present invention, the curvature radius r1 of the contour portion 7 is preferably 1.5 to 3.0 times the groove width W1. In addition, the length L1 of the first recessed portion 11 in the tire circumferential direction is preferably 2.0 to 3.0 times the groove width W1 of the main groove 3.

[0354] Figure 5 (a) shows Figure 4 The BB cross-sectional view corresponds to a cross-sectional view of the groove passing through the deepest portion 13 of the first recess 11 provided in the first groove wall 10. Figure 5 As shown in FIG. 2( a ), the first recessed portion 11 is preferably provided on the groove bottom side of the groove wall of the main groove 3 .

[0355] For example, the first recessed portion 11 according to the embodiment of the present invention includes a recessed portion 17 and a convex portion 18, the recessed portion 17 is recessed outward in the groove width direction, and the convex portion 18 is connected to the recessed portion 17 outward in the tire radial direction and convex to the groove center line side of the main groove 3. The recessed portion 17 and the convex portion 18 are each preferably curved in a smooth arc shape. However, the first recessed portion 11 is not limited to this embodiment, and may include a flat surface between the deepest portion 13 and the groove edge 6.

[0356] When viewed in the groove cross section passing through the deepest portion 13, the first recessed portion 11 preferably gradually decreases in amount from the deepest portion 13 toward the outer side in the tire radial direction. In order to ensure the groove volume of the main groove 3, the amount of recess d1 from the groove edge 6 at the deepest portion 13 is preferably 0.10 times or more, more preferably 0.20 times or more, and further more preferably 0.30 times or more of the groove width W1, which is the length between the groove edges of the main groove 3. In addition, the amount of recess d1 is not limited, but is preferably 0.50 times or less of the groove width W1, so as to facilitate the removal of the rib forming the main groove of the vulcanization mold from the tread portion.

[0357] like Figure 4As shown, the first groove wall 10 is preferably further provided with at least one second recess 12. In a preferred embodiment, the first groove wall 10 is provided with a plurality of second recesses 12. As a more preferred embodiment, in the first groove wall 10 according to the present invention, the first recesses 11 and the second recesses 12 are alternately arranged in the tire circumferential direction. The second recesses 12 are recessed outwardly from the groove edge 6 in the groove width direction, and the recessed amount of the second recesses 12 from the groove edge 6 is constant in the tire circumferential direction.

[0358] Preferably, for example, the length of the second recess 12 in the tire circumferential direction is smaller than that of the first recess 11. For example, the length L2 of the second recess 12 in the tire circumferential direction is preferably 0.45 to 0.60 times the length L1 of the first recess 11 in the tire circumferential direction. Such a second recess 12 can further improve the steering stability.

[0359] Figure 5 (b) shows Figure 4 The CC cross-sectional view corresponds to the cross-sectional view of the groove through the second recess 12 provided in the first groove wall 10. For example, Figure 5 As shown in (b), the second recess 12 includes the deepest portion 14 and the flat surface 15 between the groove edge 6, but it is not limited to this embodiment.

[0360] The angle θ1 of the plane 15 of the second recessed portion 12 is preferably, for example, 5 to 15°. Here, the angle θ1 refers to the angle between the tread normal line passing through the groove edge 6 and the plane 15 .

[0361] From the same perspective, the maximum depression amount d2 of the second recess 12 is preferably smaller than the depression amount d1 of the deepest portion 13 of the first recess 11. In addition, the depression amount d2 of the second recess 12 is preferably 0.01 to 0.25 times the groove width W1 of the main groove 3, more preferably 0.03 to 0.20 times, and even more preferably 0.05 to 0.15 times.

[0362] like Figure 4 As shown, the second groove wall 20 (another groove wall of the main groove 3) is provided with at least one first recess 11 as described above. The second groove wall 20 is further provided with at least one second recess 12 as described above. Here, Figure 5 (a) shows a groove cross-sectional view of the second recess 12 provided in the second groove wall 20, Figure 5 (b) is a groove cross-sectional view showing the first recessed portion 11 provided in the second groove wall 20 .

[0363] In a preferred embodiment, Figure 4As shown, the second groove wall 20 is provided with a plurality of first recesses 11 and a plurality of second recesses 12. As a more preferred embodiment, in the second groove wall 20 according to the present invention, the first recesses 11 and the second recesses 12 are alternately arranged in the tire circumferential direction. This can further improve the handling stability after the tread portion is worn.

[0364] In the present invention, for example, the first recessed portion 11 provided in the second groove wall 20 faces the second recessed portion 12 provided in the first groove wall 10. For example, the second recessed portion 12 provided in the second groove wall 20 faces the first recessed portion 11 provided in the first groove wall 10. Therefore, for example, the first recessed portion 11 provided in the first groove wall 10 and the first recessed portion 11 provided in the second groove wall 20 are alternately provided in the tire circumferential direction. Such arrangement of the recessed portions can reduce the increase in the air column resonance sound of the main groove.

[0365] Figure 6 An enlarged plan view of another main groove 3 according to the present invention is shown. Figure 7 Shows Figure 6 DD cross-sectional view of the main groove 3 shown in FIG. Figure 6 and Figure 7 As shown, the main groove 3 has a groove width decreasing portion 21 that gradually reduces the groove width from the groove edge 6 toward the tire radial inner side. In addition, the first recessed portion 11 is located on the tire radial inner side from the groove width decreasing portion 21. Such a main groove 3 can further suppress the deformation of the groove edge side portion 8 of the land portion of the new tire, resulting in excellent steering stability.

[0366] For example, the groove width decreasing portion 21 extends in the tire circumferential direction while having a constant cross-sectional shape. For example, the depth d4 of the groove width decreasing portion 21 is preferably 0.30 to 0.50 times the depth d3 of the main groove 3 .

[0367] For example, a plurality of first recesses 11 are provided in the tire circumferential direction, each of which is located inward in the tire radial direction from the groove width decreasing portion 21. In the present embodiment, the first recesses 11 provided in the first groove wall 10 and the first recesses 11 provided in the second groove wall 20 are alternately provided in the tire circumferential direction, each of which is located inward in the tire radial direction from the groove width decreasing portion 21. Such a main groove 3 can suppress local deformation of the land portion, thereby ensuring better steering stability.

[0368] In order to ensure the groove volume of the main groove 3, the total depression amount of the main groove 3 is preferably 0.10 to 0.90 times, more preferably 0.15 to 0.80 times, and further more preferably 0.20 to 0.70 times the groove width W1 of the main groove 3. Figure 3 implementation methods, Figure 5 implementation and Figure 7In the implementation mode of the present invention, the term "total depression amount of the main groove" refers to "C1+C2", "d1+d2" and "d1", respectively.

[0369] Example

[0370] The present invention is specifically described with reference to the embodiments, but the present invention is not limited to the embodiments.

[0371] Here, the chemicals used in the synthesis or polymerization are purified according to conventional methods, if necessary.

[0372] In addition, the methods for evaluating the prepared polymers are collectively described below.

[0373] (Measurement of weight average molecular weight (Mw))

[0374] The weight average molecular weight (Mw) of the polymer was determined by gel permeation chromatography (GPC-8000 series, available from Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M, available from Tosoh Corporation) calibrated with polystyrene standards.

[0375] (Structural Identification of Polymers)

[0376] The structure of the polymer was determined using a JNM-ECA series NMR instrument purchased from JEOL Co., Ltd. Here, the cis content was measured by infrared absorption spectroscopy.

[0377] <Production Example of Polymer>

[0378] (Polymerization of polymer A)

[0379] 1500mL of n-hexane, 25g of styrene, 75g of 1,3-butadiene, 0.2mmol of tetramethylethylenediamine and 0.24mmol of n-butyllithium were added to a heat-resistant container purged with sufficient nitrogen, and then stirred at 0°C for 48 hours. Subsequently, the reaction was terminated by adding alcohol, and 24mL of a solution of 1mmol / L BHT in ethanol was added to the reaction solution. 10mL of the polymerization solution was collected, precipitated with 40mL of ethanol, and then dried to obtain polymer A. The weight average molecular weight of the polymer (SBR) was 460,000, the styrene content was 25% by mass, and the yield was 99%.

[0380] (Polymerization of polymer B)

[0381] Preparation of catalyst solution B

[0382] In the 1L pressure-resistant stainless steel container of drying and nitrogen purge, add 350mL cyclohexane and 35g butadiene monomer.In this container, add 54mL of 20 volume % neodymium versatate solution in cyclohexane, then add 130mL of PMAO solution in toluene, then stir 30 minutes.Then, add 30mL of 1M DAIBAH solution in hexane, then stir 30 minutes.Subsequently, add 15mL of 1M 2-chloro-2-methylpropane solution in cyclohexane, then stir 30 minutes, obtain catalyst solution A.

[0383] Polymerization of polymer B

[0384] 2000mL of cyclohexane and 100g of butadiene were added to a dry and nitrogen-purged 3L pressure-resistant stainless steel container, and then 10mL of a 1mol / L TIBA solution in n-hexane was added and stirred for 5 minutes. After confirming that the solution was transparent, 30mL of catalyst solution A was added and the polymerization reaction was carried out at 80°C for 3 hours. After 3 hours, 50mL of a 1M isopropanol solution in THF was added dropwise as a reaction terminator to terminate the reaction. 10mL of the polymerization solution was collected, precipitated with 40mL of ethanol, and then dried to obtain polymer B. The weight average molecular weight of the polymer (BR) was 800,000, the cis content was 98% by mass, and the yield was 99%.

[0385] (Production of hydrogenated SBR)

[0386] n-Hexane, styrene, 1,3-butadiene, N,N,N',N'-tetramethylethylenediamine (TMEDA) and n-butyllithium were added to a heat-resistant reaction vessel fully purged with nitrogen, and then stirred at 50°C for 5 hours to carry out a polymerization reaction. Thereafter, the reaction was stirred for 20 minutes while hydrogen was supplied at a gauge pressure of 0.4 MPa, so that the unreacted polymer terminal lithium reacted with hydrogen to form lithium hydride. Hydrogenation was carried out using a titanocene dichloride catalyst under the conditions of a hydrogen supply pressure of 0.7 MPa gauge pressure and a reaction temperature of 90°C. Once the cumulative amount of absorbed hydrogen reached an amount corresponding to the target degree of hydrogenation, the reaction temperature was lowered to room temperature and the hydrogen pressure was restored to normal pressure. Then, the reaction solution was extracted from the reaction vessel, introduced into water under stirring, and the solvent was removed by steam stripping to obtain hydrogenated SBR.

[0387] (Production Example A-1) Production of Polymer Composite Material A-1

[0388] To the polymerization solution of polymer A (equivalent to 100 g of solid, solvent: n-hexane), 100 g of isopropyl acrylamide (NIPAM) and 16.7 mmol of azobisisobutyronitrile (AIBN) were added, followed by stirring at 70°C to 110°C for 5 hours. The solvent was distilled off, and the resulting product was dried under reduced pressure at 80°C and 1 mmHg until the drying loss was less than 0.5%, and then pressed into a 2 mm thick sheet. 1 The reaction rate determined by H-NMR from the protons before (NIPAM) and after (PNIPAM) the reaction was 99%.

[0389] (Production Example A-2) Production of Polymer Composite Material A-2

[0390] The same procedure as in Preparation Example A-1 was followed except that ethyl vinyl ether (EVE) was used instead of NIPAM. 1 The reaction rate determined by H-NMR from the protons before (EVE) and after (PEVE) the reaction was 99%.

[0391] (Production Example B-1) Production of Polymer Composite Material B-1

[0392] The same procedure as in Preparation Example A-1 was followed except that the polymer B was used instead of the polymer and the solvent was changed to cyclohexane. 1 The reaction rate determined by H-NMR from the protons before (NIPAM) and after (PNIPAM) the reaction was 99%.

[0393] (Production Example B-2) Production of Polymer Composite Material B-2

[0394] The same procedure as in Preparation Example B-1 was followed except that ethyl vinyl ether (EVE) was used instead of NIPAM. 1 The reaction rate determined by H-NMR from the protons before (EVE) and after (PEVE) the reaction was 99%.

[0395] The production conditions and other information of the polymer composites are collectively shown in Table 2.

[0396] [Table 2]

[0397]

[0398] The chemicals used in the following examples and comparative examples are listed below.

[0399] SBR: polymer A above

[0400] BR: polymer B mentioned above

[0401] Hydrogenated SBR: the above-mentioned hydrogenated SBR (conjugated diene unit: 3.3 mol%, non-conjugated olefin unit: 88.2 mol%, aromatic vinyl unit: 8.5 mol% (styrene content: 25 mass%), Mw: 450,000)

[0402] Carbon black: N134(N 2 SA: 148m 2 / g, DBP: 123mL / 100g), purchased from Cabot (Japan)

[0403] Silicon dioxide 1: ULTRASIL VN3 (N 2 SA: 175m 2 / g, CTAB specific surface area: 166m 2 / g), purchased from Evonik Degussa

[0404] Silica 2: ZEOSIL 115GR(N 2 SA: 112m 2 / g, CTAB specific surface area: 116m 2 / g), purchased from Rhodia

[0405] Silane coupling agent: Si69 (bis(3-triethoxysilylpropyl)tetrasulfide), purchased from Evonik Degussa

[0406] Polymer composite material A-1: ​​the above-mentioned polymer composite material A-1

[0407] Polymer composite material A-2: the above-mentioned polymer composite material A-2

[0408] Polymer composite material B-1: the above-mentioned polymer composite material B-1

[0409] Polymer composite material B-2: the above-mentioned polymer composite material B-2

[0410] Resin: Sylvares SA85 (copolymer of α-methylstyrene and styrene, softening point: 85°C), purchased from Arizona Chemical Company

[0411] Oil: Diana process AH, purchased from Idemitsu Kosan Co., Ltd.

[0412] Liquid farnesene polymer: L-FBR-742 (liquid farnesene-butadiene copolymer), purchased from Kuraray Co., Ltd.

[0413] Stearic acid: stearic acid, purchased from NOF Corporation

[0414] Zinc oxide: Zinc oxide No. 1, purchased from Mitsui Mining and Smelting Co., Ltd.

[0415] Wax: Ozoace 0355, purchased from Nippon Seira Co., Ltd.

[0416] Antioxidant 1: NOCRAC 6C (N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine), purchased from Ouchi Shinko Chemical Industry Co., Ltd.

[0417] Antioxidant 2: NOCRAC 224 (poly(2,2,4-trimethyl-1,2-dihydroquinoline)), purchased from Ouchi Shinko Chemical Industry Co., Ltd.

[0418] Sulfur: Powdered sulfur purchased from Tsurumi Chemical Industry Co., Ltd.

[0419] Vulcanization accelerator 1: NOCCELER CZ (N-cyclohexyl-2-benzothiazolylsulfenamide), purchased from Ouchi Shinko Chemical Industry Co., Ltd.

[0420] Vulcanization accelerator 2: NOCCELER D (1,3-diphenylguanidine), purchased from Ouchi Shinko Chemical Industry Co., Ltd.

[0421] (Examples and Comparative Examples)

[0422] According to the formulations shown in Tables 3 to 6, chemicals other than sulfur and vulcanization accelerators were kneaded at 150°C for 5 minutes using a 1.7L Banbury mixer (Kobe Steel) to obtain a kneaded mixture. Then, the kneaded mixture was kneaded with sulfur and vulcanization accelerators in an open roll mill at 80°C for 5 minutes to obtain an unvulcanized rubber composition. The unvulcanized rubber composition was formed into the shape of a tread and assembled with other tire components to prepare an unvulcanized tire. The unvulcanized tire was vulcanized at 170°C to obtain a test tire (size: 205 / 65R15, rim: 15×6.0J, internal pressure: 230kPa).

[0423] It should be noted that in Tables 3 to 6, the conjugated diene polymer (rubber component) contained in each polymer composite material is taken into account to adjust the rubber component content to 100 parts by mass.

[0424] It should be noted that the tread of each tire is provided with at least one main groove extending continuously in the tire circumferential direction, and the groove structure of each tire is designed to have S shown in Tables 3 to 6. 0 and S 50 .

[0425] The contact patch shape of each test tire was determined as follows: the tire was mounted on a regular rim, ink was applied to the tread portion, and the tread portion was vertically pressed against paper under a load of 70% of the maximum load capacity to transfer the ink applied to the tread portion. 0The calculation is performed as follows: the area defined by the contour of the contact shape is regarded as the entire tread contact area that would be obtained if all grooves were not provided, and in the portion without ink, the total groove area that can be retained after the main groove is worn 50% without changing the tread radius. In addition, the sea ratio S 50 Calculations are performed similar to those above: determine the total tread contact area that would be obtained assuming that all grooves in the tread portion were not provided and determine the total groove area (determined after 50% wear) that would remain after the main grooves have worn 50% without changing the tread radius.

[0426] (Rubber hardness (Hs))

[0427] The hardness of the rubber sample cut out from the tread of each test tire was measured. Specifically, the hardness of the sample (JIS-A hardness) was measured using a type A durometer according to JIS K 6253-3 (2012) "Rubber, vulcanized or thermoplastic rubber - Determination of hardness - Part 3: Durometer method". The measurement was performed at 0°C or 60°C.

[0428] The tread portion of each new test tire was worn along the tread radius until the deepest main groove in the tire reached 50% of the main groove depth of the new tire. The tire was then heat-degraded at 80°C for 7 days to prepare the worn test tires. Each worn test tire was evaluated as follows. Tables 3 to 6 show the results.

[0429] (Handling stability on wet roads after wear)

[0430] The worn test tires were mounted on each wheel of a car (a 2000cc front-engine, front-wheel drive car made in Japan). The driver drove the car on a wet asphalt road in a test field and sensory evaluated the handling stability. The results were then expressed as an index relative to the results of Comparative Example 1, with the results of Comparative Example 1 being taken as 100. A higher index indicates better handling stability on a wet road after wear.

[0431] (Handling stability on icy roads after wear)

[0432] The worn test tire was mounted on each wheel of a car (a 2000cc front-engine, front-wheel drive car made in Japan). The driver drove the car on an icy road in a test field and sensory evaluated the handling stability. Then, the results were expressed as an index relative to the result of Comparative Example 1, with the result of Comparative Example 1 being taken as 100. A higher index indicates better handling stability on an icy road after wear.

[0433] The sum of the two indices of steering stability on wet roads after wear and steering stability on icy roads after wear is defined as overall performance (in terms of steering stability on wet roads after wear and steering stability on icy roads after wear). Here, when the sum is large but one of the indices is less than 100, the overall performance is considered to be poor.

[0434] [Table 3]

[0435]

[0436] [Table 4]

[0437]

[0438] [Table 5]

[0439]

[0440] [Table 6]

[0441]

[0442] As shown in Tables 3 to 6, the overall performance (in terms of handling stability on a worn wet road and handling stability on a worn icy road) of the example tire is excellent, the tire having a tread portion having at least one main groove extending continuously in the tire circumferential direction; the tread portion comprising rubber having a hardness at 60° C. or more that is a predetermined hardness and a hardness at 0° C. that is not more than a predetermined percentage of the hardness at 60° C.; and the S 50 / S 0 The ratio is greater than 1, where S 0 Indicates the proportion of sea in the tread contact area of ​​a new tire (%), S 50 It indicates the sea ratio (%) when the tread portion is worn until the main groove depth reaches 50% of the main groove depth of a new tire.

[0443] Exemplary embodiments of the present invention include:

[0444] Embodiment 1. A tire having a tread portion,

[0445] The tread portion has at least one main groove extending continuously in the tire circumferential direction.

[0446] The tread portion includes a rubber having a hardness of 58 or more at 60° C. and a hardness of not more than 115% of the hardness at 0° C.,

[0447] The tread portion S 50 / S 0 The ratio is greater than 1, where S 0 Indicates the proportion of sea in the tread contact area of ​​a new tire (%), S50 It indicates the sea ratio (%) when the tread portion is worn until the main groove depth reaches 50% of the main groove depth of a new tire.

[0448] Embodiment 2. The tire according to embodiment 1,

[0449] Among them, the S 50 / S 0 The ratio is 1.05 to 1.40.

[0450] Embodiment 3. The tire according to embodiment 1 or 2,

[0451] The rubber contained in the tread portion has a hardness of 59 or more at 60°C.

[0452] Embodiment 4. The tire according to any one of embodiments 1 to 3,

[0453] The hardness of the rubber contained in the tread portion at 0°C is not more than 110% of the hardness at 60°C.

[0454] Embodiment 5. The tire according to any one of embodiments 1 to 4,

[0455] Here, the rubber contained in the tread portion contains a multi-component copolymer as a rubber component, the multi-component copolymer containing a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit.

[0456] Embodiment 6. The tire according to any one of embodiments 1 to 5,

[0457] Herein, the rubber contained in the tread portion contains at least one of a liquid polymer or a resin component.

[0458] Embodiment 7. The tire according to embodiment 6,

[0459] Wherein, the liquid polymer is a liquid farnesene polymer.

[0460] Embodiment 8. The tire according to embodiment 6,

[0461] The resin component is a resin that is solid at 25° C. and is an aromatic vinyl polymer, a terpene resin, a petroleum resin or a hydrogenated product thereof.

[0462] Embodiment 9. The tire according to any one of embodiments 1 to 8,

[0463] The rubber contained in the tread portion contains silica, and the amount of the silica is 80 parts by mass or more relative to 100 parts by mass of the rubber component content in the rubber.

[0464] Embodiment 10. The tire according to any one of embodiments 1 to 9,

[0465] The rubber contained in the tread portion contains CTAB with a specific surface area of ​​200 m 2 / g or more of silica.

[0466] Embodiment 11. The tire according to any one of embodiments 1 to 10,

[0467] The rubber contained in the tread portion includes a material whose hydrophilicity changes with temperature.

[0468] Embodiment 12. The tire according to embodiment 11,

[0469] The material whose hydrophilicity changes with temperature is a polymer containing a group whose hydrophilicity changes with temperature.

[0470] Embodiment 13. The tire according to embodiment 12,

[0471] Wherein, the group whose hydrophilicity changes with temperature is a temperature-responsive polymer.

[0472] Embodiment 14. The tire according to embodiment 12,

[0473] The group whose hydrophilicity changes with temperature is a polymer showing a lower critical solution temperature.

[0474] Embodiment 15. The tire according to embodiment 12,

[0475] Wherein, the group whose hydrophilicity changes with temperature is at least one of poly(N-substituted (meth)acrylamide) or poly(alkyl vinyl ether).

[0476] Reference numerals

[0477] 1 Tire

[0478] 2 Tread

[0479] 3 Main ditch

[0480] 6 Groove edge

[0481] 7 Contour of trench wall

[0482] 8 Groove edge side of the land part

[0483] 9 recess

[0484] 10 First trench wall

[0485] 11 First recess

[0486] 12 Second recess

[0487] 13, 14 deepest part

[0488] 15 Plane

[0489] 17 concave face

[0490] 18 Convex face

[0491] 20 Second trench wall

[0492] 21 Groove width decreasing portion

Claims

1. A tire having a tread portion, wherein: The tread portion has at least one main groove extending continuously in the tire circumferential direction. The tread portion includes rubber having a hardness of 58 or more at 60° C. and a hardness of not more than 115% of the hardness at 0° C., the hardness of the rubber being measured using a type A durometer in accordance with JIS K 6253-3 (2012), The tread portion S 50 / S0 ratio is greater than 1, where S0 represents the sea ratio (%) in the tread contact area of ​​a new tire, S 50 It indicates the sea ratio (%) when the tread is worn until the main groove depth reaches 50% of the main groove depth of a new tire. The rubber of the tread portion includes a material whose hydrophilicity changes with temperature. The sea ratio S0 is the ratio of the total groove area of ​​all grooves that can be retained after the main grooves are worn by 50% without changing the tread radius, measured when the tire is new, to the entire tread contact area that would be obtained if all the grooves of the tread portion were not provided. The sea ratio S 50 It refers to the percentage of the total groove area of ​​all grooves remaining after the main grooves are worn 50% without changing the tread radius, measured after the tire is worn 50%, relative to the entire tread contact area that would be obtained if all the grooves in the tread portion were not provided. The main groove refers to the deepest main groove when a plurality of main grooves of different depths are provided on the tread portion.

2. The tire according to claim 1, in, The S 50 The / S0 ratio is 1.05 to 1.

40.

3. The tire according to claim 1 or 2, in, The rubber included in the tread portion has a hardness of 59 or more at 60°C.

4. The tire according to claim 1 or 2, in, The rubber contained in the tread portion has a hardness at 0°C of not more than 110% of a hardness at 60°C.

5. The tire according to claim 1 or 2, in, The rubber contained in the tread portion contains, as a rubber component, a multi-component copolymer including a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit.

6. The tire according to claim 1 or 2, in, The rubber included in the tread portion contains at least one of a liquid polymer or a resin component.

7. The tire according to claim 6, in, The liquid polymer is a liquid farnesene polymer.

8. The tire according to claim 6, in, The resin component is a resin that is solid at 25° C. and is an aromatic vinyl polymer, a terpene resin, a petroleum resin, or a hydrogenated product thereof.

9. The tire according to claim 1 or 2, in, The rubber included in the tread portion contains silica in an amount of 80 parts by mass or more relative to 100 parts by mass of a rubber component content in the rubber.

10. The tire according to claim 9, in, The rubber contained in the tread portion contains CTAB with a specific surface area of ​​200 m 2 / g or more of silica.

11. The tire according to claim 1 or 2, in, The material whose hydrophilicity changes with temperature is a polymer containing a group whose hydrophilicity changes with temperature.

12. The tire according to claim 11, in, The group whose hydrophilicity changes with temperature is a temperature-responsive polymer.

13. The tire according to claim 11, in, The group that changes its hydrophilicity with temperature is a polymer that exhibits a lower critical solution temperature.

14. The tire according to claim 11, in, The group whose hydrophilicity changes with temperature is at least one of poly(N-substituted (meth)acrylamide) or poly(alkyl vinyl ether).

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