Rubber composition and crosslinked rubber composition

Abstract

A rubber composition containing: an uncrosslinked rubber not having a hydrogen-bonding crosslinking site; and at least one polymer component selected from the group consisting of a polymer (A) having a glass transition point of 25ºC or less and comprising a side chain (a) including a hydrogen-bonding crosslinking site that has a carbonyl-containing group and / or a nitrogen-containing heterocycle, and a polymer (B) having a glass transition point of 25ºC or less and including, in a side chain thereof, a hydrogen-bonding crosslinking site and a covalent crosslinking site. The content of the polymer component is 0.01-200 parts by mass with respect to 100 parts by mass of the uncrosslinked rubber, and both the polymer (A) and the polymer (B) are reaction products of a crosslinking compound and a maleic anhydride graft-modified thermoplastic polymer having a maleinization rate of 0.1-10 mass%.

Description

[Technical Field]

[0001] The present invention relates to a rubber composition and a crosslinked rubber composition. [Background technology]

[0002] Conventionally, various types of rubber compositions have been developed to exhibit properties suited to their applications. For example, International Publication No. 2019 / 027022 (Patent Document 1) discloses a rubber composition comprising: a rubber having no hydrogen-bond cross-linkable moieties; at least one polymer component selected from the group consisting of a polymer (A) having a side chain (a) containing a hydrogen-bond cross-linkable moiety having a carbonyl-containing group and / or a nitrogen-containing heterocycle and having a glass transition temperature of 25°C or lower; and a polymer (B) having a side chain containing a hydrogen-bond cross-linkable moiety and a covalent-bond cross-linkable moiety and having a glass transition temperature of 25°C or lower; and clay; wherein the content of the polymer component is 0.01 to 300 parts by mass per 100 parts by mass of the rubber, and the content of the clay is 20 parts by mass or less per 100 parts by mass of the polymer component. When such a rubber composition as described in Patent Document 1 is crosslinked, it is possible to obtain a rubber composition having a tan δ (0°C) value, which is an index of wet grip performance, and a tan δ (60°C) value, which is an index of rolling resistance (fuel economy), at a sufficient level and in a well-balanced manner, and the rubber composition is particularly useful as a tire material, etc. However, the rubber composition as described in Patent Document 1 has room for improvement in terms of achieving a sufficiently low hardness after crosslinking, sufficiently preventing the occurrence of oil bleeding, and furthermore, having excellent heat aging resistance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 027022 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made in view of the problems associated with the above-mentioned prior art, and aims to provide a rubber composition that, after crosslinking (vulcanization), has a sufficiently low hardness while being capable of sufficiently preventing the occurrence of oil bleeding and exhibiting excellent heat aging resistance, and a crosslinked rubber composition that is the crosslinking reaction product thereof. [Means for solving the problem]

[0005] As a result of intensive research into achieving the above object, the present inventors have found that by providing a rubber composition comprising an uncrosslinked rubber having no hydrogen-bond crosslinkable moieties and at least one polymer component selected from the group consisting of the following polymer (A) and the following polymer (B), in which the content of the polymer component is 0.01 to 200 parts by mass per 100 parts by mass of the uncrosslinked rubber, and in which both the polymer (A) and the polymer (B) are reaction products of a maleic anhydride graft-modified thermoplastic polymer having a maleation rate of 0.1 to 10% by mass with a crosslinking compound, when the rubber composition is crosslinked (vulcanized), it is possible to provide a rubber composition having a sufficiently low hardness, to sufficiently prevent the occurrence of oil bleeding, and to exhibit excellent heat aging resistance, and have completed the present invention.

[0006] That is, the rubber composition of the present invention is an uncrosslinked rubber having no hydrogen-bond crosslinkable site; at least one polymer component selected from the group consisting of a polymer (A) having a side chain (a) containing a hydrogen-bond cross-linkable moiety having a carbonyl-containing group and / or a nitrogen-containing heterocycle and having a glass transition point of 25°C or lower, and a polymer (B) having a side chain containing a hydrogen-bond cross-linkable moiety and a covalent-bond cross-linking moiety and having a glass transition point of 25°C or lower; a rubber crosslinking agent; and the uncrosslinked rubber is at least one selected from the group consisting of diene rubbers having no hydrogen-bond crosslinkable moiety and hydrogenated products thereof, The content of the polymer component is 0.01 to 200 parts by mass relative to 100 parts by mass of the uncrosslinked rubber, and Both the polymer (A) and the polymer (B) are reaction products of a maleic anhydride graft-modified thermoplastic polymer having a maleination rate of 0.1 to 10% by mass and a crosslinking compound.

[0007] The crosslinked rubber composition of the present invention is a crosslinked reaction product of the above-mentioned rubber composition of the present invention, and has a Type A durometer hardness of 0 to 70 measured under a temperature condition of 20±5°C in accordance with JIS K6253-3:2012. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a rubber composition that has a sufficiently low hardness after crosslinking (after vulcanization), can sufficiently prevent the occurrence of oil bleeding, and can also exhibit excellent heat aging resistance, and a crosslinked rubber composition that is the crosslinking reaction product thereof. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described in detail below based on preferred embodiments thereof.

[0010] (Rubber composition) The rubber composition of the present invention comprises an uncrosslinked rubber having no hydrogen-bond crosslinkable moieties, and at least one polymer component selected from the group consisting of the polymer (A) and the polymer (B), wherein the content of the polymer component is 0.01 to 200 parts by mass per 100 parts by mass of the uncrosslinked rubber, and both the polymer (A) and the polymer (B) are reaction products of a maleic anhydride-grafted thermoplastic polymer having a maleination rate of 0.1 to 10% by mass and a crosslinking compound. Hereinafter, each component will be described first.

[0011] (uncrosslinked rubber) The uncrosslinked rubber according to the present invention does not have any hydrogen-bond crosslinkable moieties and is in an uncrosslinked (unvulcanized) state. In this rubber, "not having any hydrogen-bond crosslinkable moieties" means that it does not have any moieties that crosslink via hydrogen bonds between rubbers (for example, between diene-based rubbers when the rubber is a diene-based rubber) or between other components, and does not have any structural moieties that can form crosslinks via hydrogen bonds (for example, groups such as hydroxyl groups and carbonyl groups that can form crosslinks via hydrogen bonds). Furthermore, "uncrosslinked" in this rubber refers to a state before crosslinking (vulcanization) by reaction with a rubber crosslinking agent (vulcanizing agent) described below. From this perspective, "uncrosslinked rubber" refers to rubber that has not reacted with a rubber crosslinking agent (vulcanizing agent) (rubber that has not formed crosslinks with a rubber crosslinking agent (vulcanizing agent): unvulcanized rubber). The "rubber cross-linking agent" referred to here may be any agent capable of cross-linking (vulcanizing) the uncross-linked rubber, and includes not only sulfur-based agents (sulfur-based cross-linking agents) but also non-sulfur-based agents (non-sulfur-based cross-linking agents, for example, peroxide-based cross-linking agents). Such agents that can be used as "rubber cross-linking agents" will be described later.

[0012] Suitable examples of such uncrosslinked rubbers that do not have a hydrogen-bond crosslinkable moiety include diene rubbers that do not have a hydrogen-bond crosslinkable moiety, hydrogenated diene rubbers that do not have a hydrogen-bond crosslinkable moiety, silicone rubbers that do not have a hydrogen-bond crosslinkable moiety, chlorosulfonated polyethylene rubbers that do not have a hydrogen-bond crosslinkable moiety, epichlorohydrin rubbers that do not have a hydrogen-bond crosslinkable moiety, polysulfide rubbers that do not have a hydrogen-bond crosslinkable moiety, fluororubbers that do not have a hydrogen-bond crosslinkable moiety, and vinyl chloride rubbers that do not have a hydrogen-bond crosslinkable moiety (however, such uncrosslinked rubbers that do not have a hydrogen-bond crosslinkable moiety do not include those that correspond to the "styrene block copolymers that do not have a chemically crosslinkable moiety" and the "α-olefin polymers that do not have a chemically crosslinkable moiety" described below). One type of rubber that does not have a hydrogen-bond crosslinkable moiety may be used alone, or two or more types may be used in combination (blended).

[0013] The diene rubber having no hydrogen-bond cross-linkable moieties, hydrogenated diene rubber having no hydrogen-bond cross-linkable moieties, silicone rubber having no hydrogen-bond cross-linkable moieties, chlorosulfonated polyethylene rubber having no hydrogen-bond cross-linkable moieties, epichlorohydrin rubber having no hydrogen-bond cross-linkable moieties, polysulfide rubber having no hydrogen-bond cross-linkable moieties, fluororubber having no hydrogen-bond cross-linkable moieties, and vinyl chloride rubber having no hydrogen-bond cross-linkable moieties that can be used as such uncross-linked rubber are not particularly limited, and known rubbers can be used as appropriate; for example, those described in WO 2019 / 027022 may be used as appropriate. However, such an uncrosslinked rubber having no hydrogen-bond crosslinkable moieties needs to be other than a "styrene block copolymer having no chemical-bond crosslinkable moieties" and an "α-olefin polymer having no chemical-bond crosslinkable moieties" described below (in other words, such an uncrosslinked rubber having no hydrogen-bond crosslinkable moieties is an uncrosslinked rubber other than an olefin polymer having no hydrogen-bond crosslinkable moieties and a styrene block copolymer having no hydrogen-bond crosslinkable moieties).

[0014] The uncrosslinked rubber not having such a hydrogen-bond crosslinkable moiety is more preferably at least one selected from the group consisting of diene rubbers not having a hydrogen-bond crosslinkable moiety and hydrogenated products thereof, and particularly preferably a diene rubber not having a hydrogen-bond crosslinkable moiety. The "diene rubber" preferably used as the uncrosslinked rubber herein may be any rubber containing a double bond in its molecular structure. Therefore, the "diene rubber" preferably used as the uncrosslinked rubber described in this specification is a concept that encompasses EPDM (ethylene-propylene-diene copolymer) and butyl rubber (IIR), as exemplified below. Furthermore, in this specification, the term "silicone rubber" may be any rubber containing a siloxane structure.

[0015] The diene rubber that can be suitably used as the uncrosslinked rubber that does not have such a hydrogen-bond crosslinkable moiety may be any rubber that does not have a hydrogen-bond crosslinkable moiety, and known diene rubbers that can be used in the production of industrial rubber parts (preferably tires) (for example, known diene rubbers such as natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), 1,2-butadiene rubber, styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), hydrogenated acrylonitrile-butadiene rubber, chloroprene rubber (CR), butyl rubber (IIR), brominated butyl rubber, chlorinated butyl rubber, and ethylene-propylene-diene rubber (EPDM)) can be used as appropriate.

[0016] Among these diene rubbers, from the viewpoint that when the composition is used as a material for producing industrial rubber parts (preferably tires, belts, hoses), industrial rubber parts (preferably tires, belts, hoses) with better performance can be obtained, natural rubber (NR), styrene-butadiene rubber (SBR), ethylene-propylene-diene rubber (EPDM), butadiene rubber (BR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), hydrogenated acrylonitrile-butadiene rubber, brominated butyl rubber, and chlorinated butyl rubber are preferred, with NR, SBR, EPDM, IR, BR, NBR, CR, and IIR being more preferred, with NR, SBR, and EPDM being even more preferred, and EPDM being particularly preferred. Such diene rubbers may be used alone, or two or more may be used in combination (blended) together.

[0017] The SBR that can be used as such a diene rubber may be either emulsion-polymerized SBR (E-SBR) or solution-polymerized SBR (S-SBR). When SBR is blended with other diene rubbers, it is preferable that the other diene rubbers be natural rubber, butadiene rubber, or both. A blend of diene rubbers may be used as such a diene rubber to achieve optimal performance depending on the application. For example, from the viewpoint of using the composition as a material for forming the tread portion of a tire, a diene rubber containing 30 to 100% by mass of SBR can be suitably used. Furthermore, from the viewpoint of using the composition as a material for forming the cap tread portion of a tire, a diene rubber containing 40 to 100% by mass of SBR can be suitably used.

[0018] Furthermore, from the viewpoint of versatility and performance, the uncrosslinked rubber having no hydrogen-bond crosslinkable moiety is preferably SBR, CR, IIR, EPDM, millable silicone rubber, NR, IR, BR, NBR, hydrogenated acrylonitrile-butadiene rubber, brominated butyl rubber, or chlorinated butyl rubber, with SBR, IIR, EPDM, NR, hydrogenated acrylonitrile-butadiene rubber, brominated butyl rubber, or chlorinated butyl rubber being more preferred. Note that such rubber having no hydrogen-bond crosslinkable moiety may be used alone or in the form of a mixture of two or more types.

[0019] (polymer component) The polymer component according to the present invention comprises at least one polymer selected from the group consisting of polymer (A) having a side chain (a) containing a hydrogen-bond cross-linkable moiety having a carbonyl-containing group and / or a nitrogen-containing heterocycle and having a glass transition point of 25°C or lower, and polymer (B) having a side chain containing a hydrogen-bond cross-linkable moiety and a covalent-bond cross-linking moiety and having a glass transition point of 25°C or lower.

[0020] In these polymers (A) and (B), the term "side chain" refers to the side chain and terminal of the polymer. Furthermore, the term "side chain (a) containing a hydrogen-bond cross-linkable moiety having a carbonyl-containing group and / or a nitrogen-containing heterocycle" means that the carbonyl-containing group and / or the nitrogen-containing heterocycle (more preferably the carbonyl-containing group and the nitrogen-containing heterocycle) serving as the hydrogen-bond cross-linkable moiety is chemically stablely bonded (covalently bonded) to an atom (usually a carbon atom) forming the main chain of the polymer. Furthermore, the phrase "the side chain contains a hydrogen-bond cross-linkable moiety and a covalent-bond cross-linking moiety" refers to a concept including a case where both a side chain having a hydrogen-bond cross-linkable moiety (hereinafter, for convenience, sometimes referred to as "side chain (a')") and a side chain having a covalent-bond cross-linking moiety (hereinafter, for convenience, sometimes referred to as "side chain (b)") are contained, thereby causing the side chain of the polymer to contain both a hydrogen-bond cross-linkable moiety and a covalent-bond cross-linking moiety, as well as a case where both a side chain having both a hydrogen-bond cross-linkable moiety and a covalent-bond cross-linking moiety (a side chain containing both a hydrogen-bond cross-linkable moiety and a covalent-bond cross-linking moiety in one side chain: hereinafter, such a side chain is occasionally referred to as "side chain (c)" for convenience), thereby causing the side chain of the polymer to contain both a hydrogen-bond cross-linkable moiety and a covalent-bond cross-linking moiety.

[0021] From the viewpoint of achieving a lower hardness, such a polymer component is more preferably at least one selected from the group consisting of polymers (B) containing a hydrogen-bond cross-linkable moiety and a covalent-bond cross-linking moiety in the side chain and having a glass transition point of 25°C or lower.

[0022] The main chains (types of polymers forming the main chain portion) of the polymers (A) to (B) in such polymer components are derived from the main chain of the maleic anhydride graft-modified thermoplastic polymer, since the polymers (A) to (B) are reaction products of the maleic anhydride graft-modified thermoplastic polymer and the crosslinking compound. The thermoplastic polymer forming the main chain portion of the polymers (A) to (B) (the main chain of the maleic anhydride graft-modified thermoplastic polymer) will be described later.

[0023] As described above, the glass transition points of all of these polymers (A) and (B) are 25°C or lower. In the present invention, the "glass transition point" refers to a glass transition point measured by differential scanning calorimetry (DSC). The measurement is performed at a temperature rise rate of 10°C / min. By setting the glass transition point of such a polymer to 25°C or lower, it becomes possible to impart flexibility in the normal use temperature range (room temperature (25°C) or higher).

[0024] As described above, the polymers (A) and (B) have at least one of the following side chains: a side chain (a) containing a hydrogen-bond cross-linkable moiety having a carbonyl-containing group and / or a nitrogen-containing heterocycle; a side chain (a') containing a hydrogen-bond cross-linkable moiety and a covalent-bond cross-linking moiety; and a side chain (c) containing a hydrogen-bond cross-linkable moiety and a covalent-bond cross-linking moiety. In the present invention, the side chain (c) can also be said to function as both the side chain (a') and the side chain (b). Each side chain will be described below.

[0025] <Side Chain (a'): Side Chain Containing a Hydrogen-Bond Cross-Linking Moiety> The side chain (a') containing such a hydrogen-bond cross-linkable moiety has a group capable of forming a cross-link via a hydrogen bond (e.g., a hydroxyl group, a hydrogen-bond cross-linkable moiety contained in the side chain (a) described below, etc.), and the side chain may be one that forms a hydrogen bond based on the group, and its structure is not particularly limited. Here, the hydrogen-bond cross-linkable moiety is a moiety that cross-links polymer molecules together by hydrogen bonding. Note that a cross-link via a hydrogen bond can only be formed in the presence of a hydrogen acceptor (e.g., a group containing an atom containing a lone electron pair) and a hydrogen donor (e.g., a group having a hydrogen atom covalently bonded to an atom with high electronegativity). Therefore, a cross-link via a hydrogen bond cannot be formed between the side chains of polymer molecules unless both a hydrogen acceptor and a hydrogen donor are present between the side chains of polymer molecules. Therefore, a hydrogen-bond cross-linkable moiety can only be present in a system when both a hydrogen acceptor and a hydrogen donor are present between the side chains of polymer molecules. In the present invention, when both a moiety capable of functioning as a hydrogen acceptor (for example, a carbonyl group) and a moiety capable of functioning as a hydrogen donor (for example, a hydroxyl group) are present between side chains of polymer molecules, the moiety capable of functioning as a hydrogen acceptor and the moiety capable of functioning as a hydrogen donor in the side chain can be determined to be hydrogen-bond cross-linkable moieties.

[0026] From the viewpoint of forming stronger hydrogen bonds, the hydrogen-bond cross-linkable moiety in the side chain (a') is more preferably the side chain (a) described below. From the same viewpoint, the hydrogen-bond cross-linkable moiety in the side chain (a') is more preferably a hydrogen-bond cross-linkable moiety having a carbonyl-containing group and a nitrogen-containing heterocycle.

[0027] <Side Chain (a): Side Chain Containing a Carbonyl-Containing Group and / or a Hydrogen-Bond Cross-Linkable Moiety Having a Nitrogen-Containing Heterocycle> The side chain (a) containing a hydrogen-bond cross-linkable moiety having a carbonyl-containing group and / or a nitrogen-containing heterocycle is not particularly limited as long as it has a carbonyl-containing group and / or a nitrogen-containing heterocycle. As such a hydrogen-bond cross-linkable moiety, one having a carbonyl-containing group and a nitrogen-containing heterocycle is more preferred.

[0028] Such a carbonyl-containing group is not particularly limited as long as it contains a carbonyl group, and specific examples include amide, ester, imide, carboxy, carbonyl, thioester, and acid anhydride groups. In the present invention, both polymers (A) and (B) are reaction products of a maleic anhydride-grafted thermoplastic polymer and a crosslinking compound, and therefore contain a group derived from the "maleic anhydride group" of the maleic anhydride-grafted thermoplastic polymer (e.g., an ester group, a carbonyl group, an amide group, an imide group, a carboxy group, etc., depending on the type of crosslinking compound reacted). Furthermore, the remaining unreacted acid anhydride group is a moiety that can function as a hydrogen acceptor and can therefore function as a group that forms a hydrogen-bond crosslinkable moiety.

[0029] Furthermore, when the side chain (a) has a nitrogen-containing heterocycle, the nitrogen-containing heterocycle may be introduced into the side chain (a) directly or via an organic group, and its structure is not particularly limited. Such a nitrogen-containing heterocycle may contain a heteroatom other than the nitrogen atom, such as a sulfur atom, an oxygen atom, or a phosphorus atom, as long as it contains a nitrogen atom in the heterocycle. Such a nitrogen-containing heterocycle may have a substituent. The use of a nitrogen-containing heterocycle in the side chain (a) is preferred because the heterocyclic structure strengthens the hydrogen bonds that form crosslinks, thereby improving the durability and impact resistance of the composition. Furthermore, such a nitrogen-containing heterocycle is preferably a 5-membered ring and / or a 6-membered ring, from the viewpoint of strengthening the hydrogen bonds and improving the resistance to compression set and mechanical strength. Furthermore, such a nitrogen-containing heterocycle may be a nitrogen-containing heterocycle fused with a benzene ring or a nitrogen-containing heterocycle fused with another nitrogen-containing heterocycle. As such a nitrogen-containing heterocycle, known compounds (for example, those described in paragraphs

[0054] to

[0067] of Japanese Patent No. 5918878, those described in paragraphs

[0035] to

[0048] of Japanese Patent Laid-Open No. 2017-206604, etc.) can be used as appropriate. Note that such a nitrogen-containing heterocycle may have a substituent.

[0030] From the viewpoint of achieving excellent recyclability, compression set, hardness, and mechanical strength (particularly tensile strength), such a nitrogen-containing heterocycle is preferably at least one selected from a triazole ring, an isocyanurate ring, a thiadiazole ring, a pyridine ring, an imidazole ring, a triazine ring, and a hydantoin ring, each of which may have a substituent, and more preferably at least one selected from a triazole ring, an isocyanurate ring, a thiadiazole ring, a pyridine ring, an imidazole ring, and a hydantoin ring, each of which may have a substituent.

[0031] Examples of substituents that such nitrogen-containing heterocycles may have include hydroxyl groups, amino groups, imino groups, carboxy groups, isocyanate groups, epoxy groups, alkoxysilyl groups, and thiol groups (mercapto groups). Examples of such substituents include alkyl groups such as methyl groups, ethyl groups, (iso)propyl groups, and hexyl groups; alkoxy groups such as methoxy groups, ethoxy groups, and (iso)propoxy groups; groups containing halogen atoms such as fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms; cyano groups; amino groups; imino groups; aromatic hydrocarbon groups; ester groups; ether groups; acyl groups; and thioether groups. The substitution positions of these substituents are not particularly limited, and the number of substituents is also not limited.

[0032] In addition, when the side chain (a) contains both the carbonyl-containing group and the nitrogen-containing heterocycle, the carbonyl-containing group and the nitrogen-containing heterocycle may be introduced into the main chain as independent side chains, but it is preferable that the carbonyl-containing group and the nitrogen-containing heterocycle are introduced into the main chain as a single side chain in which they are bonded via different groups. The structure of such side chain (a) may be, for example, a structure such as that described in paragraphs

[0068] to

[0081] of Japanese Patent No. 5918878.

[0033] The side chain (a) is formed by the reaction of a maleic anhydride-grafted thermoplastic polymer with a crosslinking compound. A suitable crosslinking compound used to form the side chain (a) is a compound capable of reacting with a maleic anhydride group to form a hydrogen-bond crosslinkable moiety (hereinafter, sometimes simply referred to as a "compound that forms a hydrogen-bond crosslinkable moiety"). A suitable "compound that forms a hydrogen-bond crosslinkable moiety" that can be used as the crosslinking compound is a compound that can introduce a nitrogen-containing heterocycle. Thus, a suitable crosslinking compound is a "compound that forms a hydrogen-bond crosslinkable moiety (more preferably, a compound that can introduce a nitrogen-containing heterocycle)." Such a "compound that forms a hydrogen-bond crosslinkable moiety (more preferably, a compound that can introduce a nitrogen-containing heterocycle)" is, for example, preferably a compound having a substituent that reacts with a maleic anhydride group (e.g., a hydroxyl group, a thiol group, an amino group, an imino group, etc.), and more preferably a compound having at least one of a hydroxyl group, an amino group, an imino group, and a thiol group. Furthermore, it is particularly preferable that such a compound having a substituent that reacts with a maleic anhydride group (more preferably a compound having at least one of a hydroxyl group, an amino group, an imino group, and a thiol group) has a nitrogen-containing heterocycle.

[0034] <Side chain (b): Side chain containing a covalent cross-linking moiety> In this specification, the term "side chain (b) containing a covalent cross-linking moiety" refers to a side chain containing a moiety that cross-links polymer molecules forming the main chain together by a covalent bond (covalent cross-linking moiety: for example, a moiety that cross-links polymer molecules together by a chemically stable bond (covalent bond) such as at least one bond selected from the group consisting of amide, ester, and thioester, which can be formed by reacting a maleic anhydride group with a cross-linking compound). The side chain (b) is a side chain containing a covalent-bond cross-linking moiety, but when it has a covalent-bonding moiety and also has a group capable of hydrogen bonding, and cross-linking by hydrogen bonding is formed between side chains, it will be used as side chain (c) described below. (Note that when both a hydrogen donor and a hydrogen acceptor capable of forming a hydrogen bond between side chains of the polymer molecules are not contained, for example, when only side chains containing an ester group (-COO-) are present in the system, no particular hydrogen bond is formed between the ester groups (-COO-), and therefore such a group does not function as a hydrogen-bond cross-linking moiety. On the other hand, when, for example, a carboxyl group or a carboxyl group is present in the system, a hydrogen bond is not formed between the ester groups (-COO-), and therefore such a group does not function as a hydrogen-bond cross-linking moiety. When the side chains of the polymer molecules each contain a structure having both a hydrogen donor moiety and a hydrogen acceptor moiety, such as a triazole ring, hydrogen bonds are formed between the side chains of the polymer molecules, resulting in the inclusion of a hydrogen-bond cross-linkable moiety. Furthermore, for example, when an ester group and a hydroxyl group coexist between the side chains of the polymer molecules and hydrogen bonds are formed between the side chains by these groups, the moiety forming the hydrogen bond is a hydrogen-bond cross-linkable moiety. Therefore, side chain (b) may be used as side chain (c) depending on the structure of side chain (b) itself, the type of substituents of the structure of side chain (b) and other side chains, etc.). The term "covalent cross-linkable moiety" as used herein refers to a moiety that cross-links polymer molecules by a covalent bond.

[0035] The side chain (b) containing such a covalent cross-linking moiety is not particularly limited, but is preferably a side chain containing a covalent cross-linking moiety formed by reacting a maleic anhydride-grafted thermoplastic polymer with a cross-linking compound consisting of a compound capable of forming a covalent cross-linking moiety upon reaction with a maleic anhydride group (functional group) (hereinafter sometimes referred to as a "compound that forms a covalent cross-linking moiety (compound that generates a covalent bond)"). The cross-link at the covalent cross-linking moiety of such side chain (b) is preferably formed by at least one bond selected from the group consisting of amide, ester, and thioester.

[0036] As a "compound forming a covalent cross-linking moiety (compound forming a covalent bond)" that can be used as such a cross-linking compound, a compound having a substituent that reacts with a maleic anhydride group (e.g., a hydroxyl group, a thiol group, an amino group, an imino group, etc.) is preferred, and a compound having at least one of a hydroxyl group, an amino group, and an imino group is more preferred. Furthermore, such a compound having a substituent that reacts with a maleic anhydride group (more preferably, a compound having at least one of a hydroxyl group, an amino group, and an imino group) is particularly preferably one having a nitrogen-containing heterocycle.

[0037] Furthermore, examples of "compounds that form covalent cross-linking moieties (compounds that generate covalent bonds)" that can be used as such cross-linking compounds include polyamine compounds having two or more amino groups and / or imino groups in one molecule (when both amino groups and imino groups are present, the total number of these groups is two or more); polyol compounds having two or more hydroxyl groups in one molecule; polyisocyanate compounds having two or more isocyanate (NCO) groups in one molecule; polythiol compounds having two or more thiol groups (mercapto groups) in one molecule; and the like. Here, the "compound that forms a covalent cross-linking moiety (compound that forms a covalent bond)" can be a compound that can introduce both the hydrogen-bond cross-linking moiety and the covalent cross-linking moiety, depending on the type of substituents possessed by the compound, the degree of progress of the reaction when the compound is used for reaction, and other factors. (For example, when a compound having three or more hydroxyl groups is used as a cross-linking compound to form a cross-linking moiety by a covalent bond, depending on the degree of progress of the reaction, two hydroxyl groups may react with the functional group (maleic anhydride group) of the maleic anhydride-grafted thermoplastic polymer, leaving the remaining hydroxyl group as a hydroxyl group. In such cases, a moiety that forms a hydrogen-bond cross-linking may also be introduced.) Therefore, the "compound that forms a covalent cross-linking moiety (compound that forms a covalent bond)" exemplified here can also include a "compound that forms both a hydrogen-bond cross-linking moiety and a covalent cross-linking moiety." From this perspective, when forming side chain (b), side chain (b) can be formed by appropriately selecting a compound from "compounds that form covalent cross-linking moieties (compounds that generate covalent bonds)" according to the intended design, or by appropriately controlling the degree of reaction progress. When the compound that forms the covalent cross-linking moiety has a heterocycle, it becomes possible to more efficiently produce a hydrogen-bond cross-linking moiety at the same time, and it becomes possible to efficiently form a side chain having the covalent cross-linking moiety as side chain (c) described below. Therefore, specific examples of compounds having such a heterocycle will be described as suitable compounds for producing side chain (c), particularly together with side chain (c). It can also be said that side chain (c) is a suitable form of side chains such as side chain (a) and side chain (b) due to its structure.

[0038] As the polyamine compound, the polyol compound, the polyisocyanate compound, and the polythiol compound that can be used as such a "compound that forms a covalent-bond cross-linking moiety (compound that generates a covalent bond)", known compounds (for example, those described in paragraphs

[0094] to

[0106] of Japanese Patent No. 5918878) can be used appropriately.

[0039] <Side Chain (c): Side Chain Containing Both Hydrogen-Bond Cross-Linking Moieties and Covalent-Bond Cross-Linking Moieties> Such a side chain (c) is a side chain containing both a hydrogen-bond cross-linkable moiety and a covalent-bond cross-linking moiety in one side chain. The hydrogen-bond cross-linkable moiety contained in such a side chain (c) is the same as the hydrogen-bond cross-linkable moiety described in the side chain (a'), and is preferably the same as the hydrogen-bond cross-linking moiety in the side chain (a). In addition, as the covalent-bond cross-linking moiety contained in the side chain (c), the same as the covalent-bond cross-linking moiety in the side chain (b) can be used (the same preferred cross-links can also be used).

[0040] Such a side chain (c) is preferably a side chain formed by reacting a maleic anhydride-grafted thermoplastic polymer with a cross-linking compound comprising a compound that reacts with a functional group (maleic anhydride group) of the maleic anhydride-grafted thermoplastic polymer to form both a hydrogen-bond cross-linkable moiety and a covalent-bond cross-linking moiety (a compound that introduces both a hydrogen-bond cross-linkable moiety and a covalent-bond cross-linking moiety).

[0041] As a "compound that forms both a hydrogen-bond cross-linkable moiety and a covalent-bond cross-linkable moiety (a compound that introduces both a hydrogen-bond cross-linkable moiety and a covalent-bond cross-linkable moiety)" that can be used as such a cross-linking compound, a compound having a substituent that reacts with a maleic anhydride group (e.g., a hydroxyl group, a thiol group, an amino group, an imino group, etc.) is preferred, and a compound having at least one of a hydroxyl group, an amino group, an imino group, and a thiol group is more preferred. Furthermore, as such a compound that forms both a hydrogen-bond cross-linkable moiety and a covalent-bond cross-linkable moiety (a compound that introduces both a hydrogen-bond cross-linkable moiety and a covalent-bond cross-linkable moiety), a compound that has a heterocycle (particularly preferably a nitrogen-containing heterocycle) and is capable of forming a covalent-bond cross-linkable moiety (a compound that forms a covalent bond) is preferred, and among these, a heterocycle-containing polyol, a heterocycle-containing polyamine, a heterocycle-containing polythiol, etc. are more preferred. In addition, the polyols, polyamines, and polythiols containing such heterocycles can be appropriately selected from the polyol compounds, polyamine compounds, and polythiol compounds described in the above section "Compounds capable of forming covalent cross-linking moieties (compounds that form covalent bonds)," except that they have a heterocycle (particularly preferably a nitrogen-containing heterocycle). Furthermore, known polyols, polyamines, and polythiols containing heterocycles (for example, those described in paragraph

[0113] of Japanese Patent Publication No. 5918878) can be appropriately selected.

[0042] (Regarding structures suitable for covalent cross-linking moieties in side chains (b) to (c)) With regard to the side chains (b) and / or (c), when the crosslink at the covalent-bond cross-linking moiety contains a tertiary amino bond (-N=) or an ester bond (-COO-), and when these bond moieties also function as hydrogen-bond cross-linking moieties, this is preferable from the viewpoint that the crosslink becomes stronger by forming a hydrogen bond with other hydrogen-bond cross-linking moieties. In this way, when the tertiary amino bond (-N=) or ester bond (-COO-) in the side chain having a covalent-bond cross-linking moiety forms a hydrogen bond with other side chains, the covalent-bond cross-linking moiety containing such a tertiary amino bond (-N=) or ester bond (-COO-) also has a hydrogen-bond cross-linking moiety and can function as the side chain (c).

[0043] Suitable examples of the compound capable of forming a covalent cross-linking moiety containing the tertiary amino bond and / or the ester bond upon reaction with the maleic anhydride group, which is a functional group in the maleic anhydride-grafted thermoplastic polymer (a compound capable of forming both a hydrogen-bond cross-linking moiety and a covalent cross-linking moiety: one type of cross-linking compound) include polyethylene glycol laurylamine (e.g., N,N-bis(2-hydroxyethyl)laurylamine), polypropylene glycol laurylamine (e.g., N,N-bis(2-methyl-2-hydroxyethyl)laurylamine), polyethylene glycol octylamine (e.g., N,N-bis(2-hydroxyethyl)octylamine), polypropylene glycol octylamine (e.g., N,N-bis(2-methyl-2-hydroxyethyl)octylamine), polyethylene glycol stearylamine (e.g., N,N-bis(2-hydroxyethyl)stearylamine), and polypropylene glycol stearylamine (e.g., N,N-bis(2-methyl-2-hydroxyethyl)stearylamine).

[0044] The crosslink at the covalent crosslinking site of the side chain (b) and / or the side chain (c) may be, for example, the same as the structure described in paragraphs

[0100] to

[0109] of JP 2017-206604 A or the structure described in paragraphs

[0055] to

[0061] of WO 2019 / 027022 A.

[0045] The side chain (a'), the side chain (a), the side chain (b), and the side chain (c) have been described above, but each group (structure) of the side chain in such a polymer can be confirmed by commonly used analytical means such as NMR or IR spectroscopy.

[0046] The polymer (A) is a polymer having the side chain (a) and a glass transition point of 25°C or lower, and the polymer (B) is a polymer containing a hydrogen-bond cross-linkable moiety and a covalent-bond cross-linking moiety in the side chain and having a glass transition point of 25°C or lower (e.g., a polymer having both the side chain (a') and the side chain (b) as side chains, or a polymer containing the side chain (c) in the side chain). As the polymer component according to the present invention, one of the polymers (A) to (B) may be used alone, or two or more of them may be used in combination.

[0047] The polymer (B) may be a polymer having both the side chain (a') and the side chain (b), or may be a polymer having the side chain (c). However, the hydrogen-bond cross-linkable moiety contained in the side chain of such polymer (B) is preferably a hydrogen-bond cross-linkable moiety having a carbonyl-containing group and / or a nitrogen-containing heterocycle (more preferably a hydrogen-bond cross-linkable moiety having a carbonyl-containing group and a nitrogen-containing heterocycle) from the viewpoint of forming stronger hydrogen bonds. Furthermore, the crosslink at the covalent-bond cross-linking moiety contained in the side chain of the polymer (B) is preferably formed by at least one bond selected from the group consisting of amide, ester, and thioester, from the viewpoint of enabling intermolecular interactions such as hydrogen bonds to be induced between side chains containing the cross-linking moiety.

[0048] Furthermore, all of the polymers (A) and (B) according to the present invention are reaction products of a maleic anhydride graft-modified thermoplastic polymer having a maleination rate of 0.1 to 10% by mass and a crosslinking compound.

[0049] Thus, the maleic anhydride-grafted thermoplastic polymer used to form the polymers (A) and (B) has a maleation ratio of 0.1 to 10 mass%. The upper limit of this numerical range of maleation ratio (0.1 to 10 mass%) is more preferably 5 mass%, even more preferably 3 mass%, particularly preferably 2.7 mass%, and most preferably 2.5 mass%. The lower limit of this numerical range of maleation ratio (0.1 to 10 mass%) is more preferably 0.2 mass%, even more preferably 0.3 mass%, and most preferably 0.5 mass%. If the maleation ratio is below the lower limit, the crosslink density cannot be sufficiently high even when the crosslinking reaction is carried out, and the mechanical properties (tensile properties, compression set) of the composition tend to decrease. On the other hand, if the maleation ratio exceeds the upper limit, the crosslink density of the resulting polymer becomes too high, making it difficult to maintain high compatibility between the polymer and rubber.

[0050] In the present invention, the value of "maleic acid ratio" (unit: mass %) is a value determined by the following [method for measuring maleic acid ratio]. [Method for measuring maleic acid ratio] First, 400 mg of the maleic anhydride-grafted thermoplastic polymer to be measured is dissolved in 80 mL of tetrahydrofuran (hereinafter, for convenience, sometimes abbreviated as "THF") to obtain a THF solution for measurement. The THF solution for measurement is then titrated with a 0.1 mol / L ethanol solution of potassium hydroxide for which a factor is calculated to three or more decimal places (volumetric standard solution: a 0.1 mol / L ethanol solution of potassium hydroxide with correction; a commercially available solution with a factor (characteristic value: corrected value) calculated to three or more decimal places may be used). The endpoint (neutralization point) is determined by potentiometric titration using an instrument. The factor (characteristic value: corrected value) of the 0.1 mol / L ethanol solution of potassium hydroxide may be determined by titration with an oxalic acid standard solution. When using a commercially available product with a calculated factor, the factor listed on the commercially available reagent (e.g., the factor listed on the reagent's test report) may be used as is. Next, a similar measurement (blank test) is performed except that no maleic anhydride-grafted thermoplastic polymer is used, and titration is performed, and the amount of 0.1 mol / L potassium hydroxide ethanol solution added to 80 mL of THF (blank value) is also determined. Next, the acid value is calculated using the determined titration value (addition amount) based on the "Acid Value Calculation Formula" below, and the maleinization ratio is then calculated using the obtained acid value based on the "Maleinization Ratio Calculation Formula" below, thereby determining the maleinization ratio (unit: mass%). <Calculation formula for acid value> [Acid value]=(AB)×M1×C×f / S (In the formula, A represents the amount of 0.1 mol / L potassium hydroxide ethanol solution added (titer value: mL) required to neutralize the measurement solution, B represents the amount of 0.1 mol / L potassium hydroxide ethanol solution added in a blank (blank test) (the titration value (blank value: mL) obtained by performing the same measurement except that no maleic anhydride graft-modified thermoplastic polymer is used), M1 represents the molecular weight of potassium hydroxide (56.1 (constant)), C represents the potassium hydroxide concentration in the potassium hydroxide ethanol solution (0.1 mol / L (constant)), f represents the factor of the potassium hydroxide ethanol solution (correction value: the factor listed in a commercially available reagent (for example, the factor listed in the test report for the reagent) may be used as is), and S represents the mass of the maleic anhydride graft-modified thermoplastic polymer used in the measurement (400 g (constant)). The unit of the "acid value" obtained by this calculation is "mgKOH / g.") <Maleate ratio calculation formula> [Maleication rate] = [Acid value] ÷ M1 × M2 ÷ 1000 × 100 ÷ 2 (In the formula, the acid value is the value (unit: mgKOH / g) calculated using the above-mentioned "acid value calculation formula," M1 is the molecular weight of potassium hydroxide (56.1 (constant)), and M2 is the molecular weight of maleic anhydride (98.1 (constant)). The unit of the "maleication ratio" calculated by this calculation is "mass %.")

[0051] Furthermore, the maleic anhydride graft-modified thermoplastic polymer used to form the polymers (A) and (B) preferably has a melting point of 64°C or less (more preferably 60°C to -100°C). If the melting point of such a maleic anhydride graft-modified thermoplastic polymer exceeds the upper limit, the hardness tends to increase. The melting point is measured by differential scanning calorimetry (DSC). The melting point is measured at a heating rate of 10°C / min.

[0052] Furthermore, the main chain of such a maleic anhydride graft-modified thermoplastic polymer (the polymer forming the main chain portion of the polymers (A) to (B)) can be one appropriately selected from so-called thermoplastic polymers (it should be noted that the "thermoplastic polymer" in the maleic anhydride graft-modified thermoplastic polymer referred to in this specification may be any polymer having thermoplastic properties, and may be, for example, so-called "elastomer" or "rubber").

[0053] The main chain of such maleic anhydride-grafted thermoplastic polymer (the polymer forming the main chain portion of polymers (A) and (B)) is not particularly limited, but is preferably a polyolefin-based polymer, a polyester-based polymer, a polyamide-based polymer, a polystyrene-based polymer, a polyacrylate-based polymer, a polyacrylonitrile-based polymer, a polyacetal-based polymer, a polycarbonate-based polymer, a polyolefin-acrylate copolymer, or a diene-based polymer, more preferably a polyolefin-based polymer, a polyacrylate-based polymer, a polyolefin-acrylate copolymer, or a diene-based polymer, even more preferably a polyolefin-based polymer, a diene-based polymer, or a polystyrene-based polymer, and most preferably a polyolefin-based polymer or a diene-based polymer. These polymers may be used singly or in combination of two or more.

[0054] Furthermore, polyolefin-based polymers suitable as the main chain of such maleic anhydride-grafted thermoplastic polymers are not particularly limited and may be polymers of α-olefins or polymers composed of copolymers of α-olefins and other copolymerizable monomers. Furthermore, diene-based polymers suitable as the main chain of such maleic anhydride-grafted thermoplastic polymers may be any polymer containing a double bond in the molecular structure, and this concept also encompasses ethylene-propylene-diene copolymers having double bonds at crosslinking sites. Furthermore, known diene-based polymers suitable as the main chain of the maleic anhydride-grafted thermoplastic polymers can be appropriately used and are not particularly limited. However, butadiene rubber (BR), natural rubber (NR), isoprene rubber (IR), and styrene-butadiene rubber (SBR) are preferred from the viewpoint of having an appropriate glass transition temperature to facilitate maintaining low hardness even at low temperatures. Furthermore, as a polystyrene-based polymer suitable for the main chain of the maleic anhydride graft-modified thermoplastic polymer, any known polymer can be used as appropriate and is not particularly limited, but from the viewpoint of improving oil retention ability, a styrene-ethylene-butylene-styrene block copolymer (SEBS) is preferred.

[0055] Among the thermoplastic polymers used in the main chain of such maleic anhydride graft-modified thermoplastic polymers, from the viewpoint of compatibility with non-polar rubbers, polypropylene (PP), polyethylene (PE), ethylene-butene copolymer (EBM), ethylene-propylene copolymer (EPM), ethylene-octene copolymer (EOM), and ethylene-propylene-diene copolymer (EPDM) are preferred, with EBM, EPM, EOM, and EPDM being more preferred, and EBM, EOM, and EPDM being even more preferred.

[0056] Furthermore, the main chain of such a maleic anhydride graft-modified thermoplastic polymer (the polymer forming the main chain portion of polymers (A) and (B)) is preferably a polymer that does not contain double bonds, from the viewpoint of improving processability and aging resistance during crosslinking. From this viewpoint, PE, EBM, and EOM are preferred as the main chain of the maleic anhydride graft-modified thermoplastic polymer, and PE, EBM, and EOM are more preferred. On the other hand, from the viewpoint of improving mechanical properties such as abrasion resistance by co-crosslinking with uncrosslinked rubber during crosslinking, a polymer that contains double bonds is preferred. From this viewpoint, EPDM is preferred as the main chain of the maleic anhydride graft-modified thermoplastic polymer.

[0057] The maleic anhydride-grafted thermoplastic polymer is a graft-modified product (thermoplastic polymer graft-modified with maleic anhydride) obtained by graft-modifying the thermoplastic polymer described above as the main chain with maleic anhydride. Therefore, the maleic anhydride-grafted thermoplastic polymer is preferably a polyolefin polymer graft-modified with maleic anhydride and / or a diene polymer graft-modified with maleic anhydride, and more preferably a maleic anhydride-grafted product of at least one thermoplastic polymer selected from the group consisting of PP, PE, EBM, EPM, EOM, and EPDM. Such maleic anhydride-grafted thermoplastic polymers may be used alone or in combination of two or more.

[0058] The maleic anhydride-grafted thermoplastic polymer is a graft-modified product (thermoplastic polymer graft-modified with maleic anhydride) obtained by graft-modifying the thermoplastic polymer with maleic anhydride, and may be any polymer that satisfies the above-mentioned maleic conversion ratio requirement. The method for producing the maleic anhydride-grafted thermoplastic polymer is not particularly limited, and the polymer can be easily produced by employing a known method for preparing a maleic anhydride-grafted thermoplastic polymer and appropriately adjusting the types and amounts of raw materials used so as to satisfy the above-mentioned requirement. Furthermore, commercially available maleic anhydride-grafted thermoplastic polymers may be used as appropriate, provided that they satisfy the above-mentioned requirement.

[0059] The crosslinking compound is not particularly limited as long as it can react with the maleic anhydride groups in the maleic anhydride-grafted thermoplastic polymer to form either the polymer (A) or (B). Depending on the intended design, a compound capable of reacting with the maleic anhydride groups to form various crosslinking moieties (a compound capable of forming the intended side chain) can be appropriately selected and used.

[0060] As such a crosslinking compound, the aforementioned "compounds that form hydrogen-bond crosslinkable moieties (more preferably, compounds that can introduce a nitrogen-containing heterocycle)" and "compounds that form covalent crosslinking moieties (compounds that form covalent bonds)" can be suitably used. Furthermore, from the viewpoint of efficient reaction progression, such crosslinking compounds are preferably compounds having at least one of a hydroxyl group, an amino group, an imino group, and a thiol group. Furthermore, as such compounds having at least one of a hydroxyl group, an amino group, an imino group, and a thiol group, those having a nitrogen-containing heterocycle (such nitrogen-containing heterocycles are more preferably at least one selected from a triazole ring, an isocyanurate ring, a thiadiazole ring, a pyridine ring, an imidazole ring, a triazine ring, and a hydantoin ring) are more preferred (note that the "nitrogen-containing heterocycle" referred to here is the same as the above, including preferred examples). As such compounds, for example, those described in paragraph

[0049] of International Publication No. 2020 / 027109 can be used as appropriate. Such compounds may be used alone or in combination of two or more.

[0061] Furthermore, from the viewpoint of high reactivity and industrial availability, such crosslinking compounds are preferably at least one compound selected from the group consisting of nitrogen-containing compounds which may have at least one substituent selected from the group consisting of hydroxyl, thiol, amino, and imino groups, oxygen-containing compounds which may have at least one substituent selected from the group consisting of hydroxyl, thiol, amino, and imino groups, and sulfur-containing compounds which may have at least one substituent selected from the group consisting of hydroxyl, thiol, amino, and imino groups. Such "compounds that form hydrogen-bond crosslinkable moieties (compounds that can introduce a nitrogen-containing heterocycle)" and "compounds that form covalent crosslinkable moieties (compounds that form covalent bonds)" can be appropriately selected from known compounds (compounds described in JP 2017-57322 A and JP 5918878 A) as long as they are capable of reacting with maleic anhydride groups.

[0062] Furthermore, such crosslinking compounds include triazoles which may have at least one substituent selected from the group consisting of hydroxyl, thiol, amino, and imino groups; pyridines which may have at least one substituent selected from the group consisting of hydroxyl, thiol, amino, and imino groups; thiadiazoles which may have at least one substituent selected from the group consisting of hydroxyl, thiol, amino, and imino groups; imidazoles which may have at least one substituent selected from the group consisting of hydroxyl, thiol, amino, and imino groups; isocyanurates which may have at least one substituent selected from the group consisting of hydroxyl, thiol, amino, and imino groups; hydroxyl groups, It is preferably at least one selected from the group consisting of triazine which may have at least one substituent selected from a thiol group, an amino group, and an imino group; hydantoin which may have at least one substituent selected from a hydroxyl group, a thiol group, an amino group, and an imino group; tris(2-hydroxyethyl)isocyanurate; 2,4-diamino-6-phenyl-1,3,5-triazine (benzoguanamine); 2,4-diamino-6-methyl-1,3,5-triazine (acetoguanamine); pentaerythritol; sulfamide; and polyether polyol.

[0063] From the viewpoint of compression set resistance, such crosslinking compounds are preferably tris(2-hydroxyethyl)isocyanurate, sulfamide, pentaerythritol, 2,4-diamino-6-phenyl-1,3,5-triazine, 2,4-diamino-6-methyl-1,3,5-triazine, or polyether polyol, and more preferably pentaerythritol, 2,4-diamino-6-phenyl-1,3,5-triazine, 2,4-diamino-6-methyl-1,3,5-triazine, or tris(2-hydroxyethyl)isocyanurate.

[0064] The method for obtaining the reaction product of the maleic anhydride graft-modified thermoplastic polymer and the crosslinking compound is not particularly limited, and any method can be used as long as it can react the maleic anhydride groups in the maleic anhydride graft-modified thermoplastic polymer with the functional groups in the crosslinking compound to form the polymers (A) and (B) (as long as it can form the crosslinked sites described for the polymers (A) and (B)). The reaction can be carried out appropriately depending on the type of the crosslinking compound, etc. For example, a method can be employed in which the maleic anhydride graft-modified thermoplastic polymer is plasticized using a kneader or other kneading machine at a temperature (e.g., about 100 to 250°C) that allows the crosslinking compound to react with the maleic anhydride groups while mixing (kneading) the maleic anhydride graft-modified thermoplastic polymer, and the crosslinking compound is added to cause the reaction.

[0065] (About the composition) The rubber composition of the present invention contains the uncrosslinked rubber having no hydrogen-bond crosslinkable moieties and the polymer component.

[0066] In such a rubber composition, the content (content ratio) of the polymer component is 0.01 to 200 parts by mass relative to 100 parts by mass of the uncrosslinked rubber. If the content of the polymer component is below the lower limit, the effect obtained by including the polymer component cannot be fully exhibited. On the other hand, if the content exceeds the upper limit, the proportion of the uncrosslinked rubber becomes too small, and when a crosslinked rubber composition is produced by crosslinking (vulcanizing) using a rubber crosslinking agent (vulcanizing agent) described below, the crosslink density decreases, and the rubber physical properties of the crosslinked rubber composition deteriorate. From the same viewpoint, the content (content ratio) of the polymer component in the rubber composition is more preferably 0.01 to 150 parts by mass, even more preferably 0.1 to 100 parts by mass, even more preferably 1 to 50 parts by mass, particularly preferably 2 to 30 parts by mass, and most preferably 5 to 15 parts by mass relative to 100 parts by mass of the uncrosslinked rubber.

[0067] Furthermore, the rubber composition of the present invention may contain other components in addition to the uncrosslinked rubber not having a hydrogen-bond crosslinkable moiety and the polymer component, within the scope of the object of the present invention, depending on the application, etc. Such other components may be any components that can be used in rubber compositions, and are not particularly limited, and known components that can be used in rubber compositions can be used appropriately.

[0068] The rubber composition of the present invention preferably further contains at least one selected from the group consisting of silica and carbon black. By including such silica and / or carbon black, it becomes possible to further increase hardness and further improve modulus and strength at break.

[0069] When the rubber composition of the present invention contains at least one selected from the group consisting of silica and carbon black, the total amount of silica and carbon black is preferably 10 to 150 parts by mass (more preferably 15 to 120 parts by mass, and even more preferably 30 to 100 parts by mass) per 100 parts by mass of the uncrosslinked rubber. If the total amount of silica and / or carbon black is less than the lower limit, the effect (reinforcing effect) obtained by adding these components tends to be insufficient, while if the total amount exceeds the upper limit, the breaking strength tends to decrease.

[0070] In addition, such silica has a BET specific surface area (based on ASTM D1993-03) of 40 to 250 m 2 / g (more preferably 70 to 200 m 2 / g) is preferred. Examples of such silica include dry-process silica (e.g., fumed silica) produced by thermal decomposition of silicon halide or organosilicon compounds, and wet-process silica produced by decomposition of sodium silicate with acid. From the standpoints of cost and performance, wet-process silica is more preferred. Furthermore, as such silica, commercially available silica for the rubber industry (commercially available products) can be used as is. Such silica may be used alone or in combination with carbon black.

[0071] Furthermore, when silica is contained in the rubber composition of the present invention, it is preferable to further contain a silane coupling agent from the viewpoint of further improving the properties required of silica and further improving dispersibility in rubber that does not have the hydrogen-bond cross-linking moiety (silica has poor affinity with rubber polymers and also has the property of forming hydrogen bonds between silica molecules in rubber through silanol groups, which reduces the dispersibility of silica in rubber). Furthermore, when such a silane coupling agent is contained, its content is preferably about 0.5 to 15 parts by weight per 100 parts by weight of silica. Furthermore, as such a silane coupling agent, polysulfide-based silane coupling agents having alkoxysilyl groups that react with silanol groups on the silica surface and sulfur chains that react with polymers, such as bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, and bis(3-triethoxysilylpropyl)disulfide, can be preferably used. As such a silane coupling agent, commercially available products can be appropriately used, and for example, products under the trade names "Si-69" and "Si-75" manufactured by Evonik Industries AG (formerly Evonik Degussa) may be used.

[0072] The carbon black is not particularly limited, and any known carbon black that can be used in a rubber composition can be used as appropriate. Among these carbon blacks, furnace blacks such as SAF, ISAF, HAF, FEF, GPF, and SRF are preferred from the viewpoints of reinforcing properties and dispersibility. As such carbon black, commercially available carbon blacks (commercial products) may be used as they are. Note that such carbon blacks are effective components when forming the tread portion of a tire, particularly the cap tread portion. Such carbon blacks may be used alone or in combination with silica.

[0073] The rubber composition of the present invention may further contain clay. Known clays (e.g., those described in paragraphs

[0146] to

[0156] of Japanese Patent No. 5918878 and those described in paragraphs

[0146] to

[0155] of JP-A No. 2017-057393) can be used as appropriate. Among these clays, from the viewpoint of high dispersibility, at least one selected from the group consisting of clays primarily composed of silicon and magnesium and organically modified clays is preferred, with organically modified clays being particularly preferred. Thus, the polymer composition of the present invention preferably further contains clay, and it is particularly preferred that the polymer composition contain organically modified clays.

[0074] When the rubber composition of the present invention contains clay, the content (content ratio) of the clay is preferably 20 parts by mass or less, more preferably 0.01 to 10 parts by mass, even more preferably 0.05 to 5 parts by mass, and particularly preferably 0.08 to 3 parts by mass, relative to 100 parts by mass of the polymer component. If the clay content is below the lower limit, the clay content tends to be too low to provide a sufficient reinforcing effect, while if the clay content exceeds the upper limit, the formation of hydrogen-bond crosslinkable sites is inhibited, reducing the reinforcing properties of the clay and making it difficult to use in various applications (reducing practicality).

[0075] From the viewpoint of moldability (fluidity), the rubber composition of the present invention preferably further contains an α-olefin polymer that does not have a chemically bonded cross-linking site. The term "α-olefin polymer" as used herein refers to an α-olefin homopolymer or an α-olefin copolymer, and the term "α-olefin" refers to an alkene having a carbon-carbon double bond at the α-position, such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, and 1-decene.

[0076] Furthermore, in this specification, the term "chemically bonded cross-linked moiety" refers to a moiety where a cross-link is formed by a chemical bond such as a hydrogen bond, a covalent bond, chelation between a metal ion and a polar functional group, a bond formed by σ-π interaction between a metal and an unsaturated bond (double bond, triple bond), etc. Therefore, in this specification, "not having a chemically bonded cross-linked moiety" refers to a state where no moiety where a cross-link is formed by a chemical bond such as a hydrogen bond, a covalent bond, or an ionic bond is included.

[0077] Suitable examples of such α-olefin polymers that do not have chemically bonded crosslinking moieties include those described in paragraphs

[0204] to

[0214] of JP 2017-57322 A. Furthermore, from the viewpoint of compatibility with the polymer components, preferred α-olefin polymers that do not have chemically bonded crosslinking moieties include polypropylene, polyethylene, ethylene-propylene copolymers, and ethylene-butene copolymers. Suitable examples of such α-olefin polymers that do not have chemically bonded crosslinking moieties include α-olefin polymers with a crystallinity of 10% or less (such as polypropylene, ethylene-propylene copolymers, ethylene-butene copolymers, polyethylene, and polybutene). There are no particular limitations on the method for producing such α-olefin polymers that do not have chemically bonded crosslinking moieties, and known methods can be appropriately adopted. Commercially available α-olefin polymers may also be used. One or more of such α-olefin polymers that do not have chemically bonded crosslinking moieties may be used alone, or two or more may be used in combination.

[0078] The content (content ratio) of such α-olefin polymer not having chemically bonded crosslinking moieties can be appropriately changed depending on the intended application and design and is not particularly limited. However, for example, it is more preferable that the content is 300 parts by mass or less (more preferably 5 to 250 parts by mass, even more preferably 10 to 225 parts by mass, particularly preferably 25 to 200 parts by mass, and most preferably 35 to 175 parts by mass) per 100 parts by mass of the polymer component. If the content is below the lower limit, sufficient fluidity tends to be insufficient. On the other hand, if the content exceeds the upper limit, rubber elasticity tends to decrease and resinous properties tend to increase (hardness becomes higher than necessary). From the same viewpoint, the content of the α-olefin polymer is preferably 0.1 to 100 parts by mass, more preferably 0.5 to 80 parts by mass, per 100 parts by mass of the uncrosslinked rubber.

[0079] Furthermore, the rubber composition of the present invention preferably further contains a styrene block copolymer that does not have a chemically bonded cross-linking moiety. As such a styrene block copolymer that does not have a chemically bonded cross-linking moiety, those described in paragraphs

[0156] to

[0163] of JP 2017-57393 A can be suitably used. The "styrene block copolymer" may be any polymer that has a styrene block structure at any site.

[0080] From the viewpoint of achieving both rubber elasticity and thermoplasticity, styrene block copolymers without chemically bonded crosslinking sites are preferably styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-propylene-styrene block copolymer (SEPS, a hydrogenated product of SIS), styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS, a hydrogenated product of SIBS), styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene-butylene-styrene block copolymer (SEBS, a hydrogenated product of SBS), and styrene-isoprene-butadiene-styrene block copolymer (SIBS), with SEBS and SEEPS being more preferred. One of these styrene block copolymers may be used alone, or two or more may be used in combination. Commercially available styrene block copolymers may be used as appropriate.

[0081] When such a styrene block copolymer is used, its content (content ratio) is not particularly limited, but is preferably 1 to 5,000 parts by mass per 100 parts by mass of the polymer component. The upper limit of the preferred numerical range of this content ratio is 5,000 parts by mass per 100 parts by mass of the polymer component, with this upper limit being more preferably 3,000 parts by mass, even more preferably 1,000 parts by mass, and particularly preferably 800 parts by mass. The lower limit of the preferred numerical range of this content ratio is 1 part by mass per 100 parts by mass of the polymer component, with this lower limit being more preferably 5 parts by mass, even more preferably 10 parts by mass. The content ratio of such a styrene block copolymer is more preferably 1 to 1,000 parts by mass, even more preferably 5 to 800 parts by mass per 100 parts by mass of the polymer component. If the content ratio is less than the lower limit, oil bleeding tends to occur when oil is added, whereas if it exceeds the upper limit, moldability tends to decrease. From the same viewpoint, the content (content ratio) of the styrene block copolymer is preferably 0.1 to 100 parts by mass, and more preferably 0.5 to 80 parts by mass, relative to 100 parts by mass of the uncrosslinked rubber.

[0082] Furthermore, it is more preferable that the rubber composition of the present invention further contains a process oil. Examples of such process oils include paraffin oil (paraffinic oil), naphthenic oil (naphthenic oil), and aromatic oil (aromatic oil). Furthermore, with regard to such paraffin oil, naphthenic oil, and aromatic oil, when the uncrosslinked rubber is a diene rubber, it is particularly preferable to use aromatic oil, and when the uncrosslinked rubber is a chloroprene rubber or butyl rubber, it is particularly preferable to use naphthenic oil in combination. Such process oil is not particularly limited, and known process oils can be used as appropriate, and commercially available ones can be used as appropriate.

[0083] Furthermore, when the polymer component contained in the rubber composition of the present invention has an olefin-based polymer as its main chain, compatibility can be improved. Therefore, it is more preferable to use paraffin oil as the process oil contained in the composition. Such paraffin oil is not particularly limited, and known paraffin oils can be used as appropriate. For example, the paraffin oils described in paragraphs

[0153] to

[0157] of JP 2017-57323 A can be suitably used. Commercially available paraffin oils can be used as appropriate.

[0084] When such a process oil (more preferably paraffin oil) is used, its content (content ratio) is not particularly limited, but is preferably 1 to 30,000 parts by mass per 100 parts by mass of the polymer component. The upper limit of the preferred range of this content ratio is 30,000 parts by mass per 100 parts by mass of the polymer component, with the upper limit being more preferably 25,000 parts by mass, even more preferably 20,000 parts by mass, even more preferably 15,000 parts by mass, even more preferably 10,000 parts by mass, even more preferably 8,000 parts by mass, even more preferably 7,000 parts by mass, particularly preferably 6,000 parts by mass, and most preferably 5,000 parts by mass. The lower limit of the preferred range of this content ratio is 1 part by mass per 100 parts by mass of the polymer component, with the lower limit being more preferably 10 parts by mass, even more preferably 30 parts by mass, especially preferably 50 parts by mass, and most preferably 75 parts by mass. The content of such process oil (more preferably paraffin oil) is more preferably 10 to 1000 parts by mass, even more preferably 30 to 900 parts by mass, particularly preferably 50 to 800 parts by mass, and most preferably 75 to 700 parts by mass, per 100 parts by mass of the polymer component. If the content of such process oil is below the lower limit, the content of process oil is too low, and sufficient effects, particularly in terms of fluidity and processability, tend to be insufficient. On the other hand, if the content exceeds the upper limit, bleeding of the process oil tends to be easily induced. From the same viewpoint, the content (content ratio) of the process oil is preferably 0.1 to 300 parts by mass, more preferably 0.5 to 200 parts by mass, per 100 parts by mass of the uncrosslinked rubber.

[0085] Furthermore, such a rubber composition preferably further contains a rubber cross-linking agent (vulcanizing agent) in order to cross-link (vulcanize) the uncross-linked rubber for use. Such a rubber cross-linking agent (vulcanizing agent) is not particularly limited as long as it is capable of cross-linking (vulcanizing) the uncross-linked rubber (e.g., the diene rubber) that does not have the hydrogen-bond cross-linkable moiety, and known cross-linking agents for rubber can be used as appropriate. Note that such a rubber cross-linking agent (vulcanizing agent) may be a so-called sulfur-based one (sulfur-based cross-linking agent) or a non-sulfur-based one (non-sulfur-based cross-linking agent: for example, a peroxide-based cross-linking agent, etc.).

[0086] Furthermore, as such a crosslinking agent for rubber (vulcanizing agent), a peroxide-based crosslinking agent, a phenolic resin-based crosslinking agent, a sulfur-based crosslinking agent, or a silane-based crosslinking agent can be suitably used. The peroxide-based crosslinking agent, phenolic resin-based crosslinking agent, sulfur-based crosslinking agent, and silane-based crosslinking agent that can be used as such a crosslinking agent for rubber are not particularly limited, and known crosslinking agents can be used as appropriate. For example, the peroxide-based crosslinking agent, phenolic resin-based crosslinking agent, sulfur-based crosslinking agent, and silane-based crosslinking agent described in WO 2019 / 027022 may be used as appropriate.

[0087] Among these rubber crosslinking agents, sulfur-based crosslinking agents and peroxide-based crosslinking agents are preferred from the viewpoint of further improving physical properties, with sulfur-based crosslinking agents being more preferred. Furthermore, among these rubber crosslinking agents, peroxide-based crosslinking agents are preferred from the viewpoint of heat aging resistance. Thus, in the present invention, from the viewpoint of heat aging resistance, it is more preferred to use a peroxide-based crosslinking agent as the rubber crosslinking agent (vulcanizing agent), and it is more preferred that the crosslinked rubber composition obtained after crosslinking has crosslinks (peroxide crosslinks) formed by the peroxide-based crosslinking agent. Furthermore, as such peroxide-based crosslinking agents, from the viewpoint of crosslinking ability, benzoyl peroxide, di-t-butyl peroxide, and dicumyl peroxide are preferred, with dicumyl peroxide being more preferred. Furthermore, as the sulfur-based crosslinking agent, from the viewpoint of reactivity, powdered sulfur, precipitated sulfur, highly dispersible sulfur, surface-treated sulfur, inert sulfur, and oil-treated sulfur are preferred, with powdered sulfur and oil-treated sulfur being more preferred, and oil-treated sulfur being even more preferred.

[0088] When such a rubber cross-linking agent is contained, it is preferable to further contain a cross-linking aid (vulcanization aid). As such a cross-linking aid, for example, known compounds (such as the compounds described in paragraph

[0088] of WO 2018 / 235961, zinc dimethacrylate, zinc diacrylate, etc.) can be appropriately used.

[0089] When the rubber cross-linking agent is contained, it is preferable to further contain a cross-linking accelerator (vulcanization accelerator). As such a cross-linking accelerator, it is preferable to use thiazole-based (MBT, MBTS, ZnMBT, etc.), sulfenamide-based (CBS, DCBS, BBS, etc.), guanidine-based (DPG, DOTG, OTBG, etc.), thiuram-based (TMTD, TMTM, TBzTD, TETD, TBTD, TOTN (tetrakis(2-ethylhexyl)thiuram disulfide)), dithiocarbamate-based (ZTC, NaBDC, etc.), thiourea-based (ETU, etc.), xanthogenate-based (ZnBX, etc.) cross-linking accelerators (vulcanization accelerators), etc.

[0090] When such a rubber cross-linking agent is used, it is preferable to use a cross-linking accelerator (vulcanization accelerator) in combination. As such a cross-linking accelerator, it is also preferable to use zinc oxide (e.g., three types of zinc oxide); fatty acids such as stearic acid, acetyl acid, propionic acid, butanoic acid, acrylic acid, and maleic acid; zinc fatty acids such as zinc acetylate, zinc propionate, zinc butanoate, zinc stearate, zinc acrylate, and zinc maleate together with the sulfur-based cross-linking agent.

[0091] When a silane-based crosslinking agent is used as the rubber crosslinking agent, a silane compound may be graft-copolymerized onto the rubber to silane-crosslink the uncrosslinked rubber. Such silane compounds preferably have a group reactive with the uncrosslinked rubber and an alkoxy group that forms a crosslink by silanol condensation. Known silane compounds (e.g., those described in International Publication No. 2019 / 027022) can be used as appropriate. When graft-copolymerizing a silane compound onto the uncrosslinked rubber, known methods (e.g., a method of mixing a predetermined amount of a silane compound and a free radical generator with the uncrosslinked rubber and melt-kneading at a temperature of 80 to 200°C) can be used as appropriate. From the viewpoint of crosslinkability, polysilanes are more preferred as such silane-based crosslinking agents.

[0092] The content of such a cross-linking agent (vulcanizing agent) for rubber is preferably 0.1 to 10 parts by mass (more preferably 0.1 to 5 parts by mass) per 100 parts by mass of the uncross-linked rubber. If the content (amount used) of such a cross-linking agent for rubber is less than the lower limit, the cross-linking density tends to be too low when cross-linked, resulting in poor physical properties. On the other hand, if the content exceeds the upper limit, the cross-linking density tends to be too high, resulting in poor physical properties.

[0093] In addition, in the rubber composition of the present invention, other additives that can be used in rubber compositions other than the above-mentioned components can be appropriately used depending on the application. As such additives, known additives that can be contained in rubber compositions can be appropriately used, and are not particularly limited. Examples of such additives include the uncrosslinked rubber, the polymer component, styrene block copolymers that do not have crosslinking sites by chemical bonding, and polymers other than α-olefin polymers that do not have crosslinking sites by chemical bonding; reinforcing agents other than the above-mentioned silica, carbon black, and clay (for example, hydrogen-bonding fillers, fillers into which amino groups have been introduced (amino group-introduced fillers), etc.); amino group-containing fillers other than the amino group-introduced fillers; Examples of the additives include compounds, compounds containing metal elements (metal salts), maleic anhydride-modified polymers, antioxidants, antioxidants, pigments (dyes), plasticizers (softeners), thixotropic agents, UV absorbers, flame retardants, solvents, surfactants (including leveling agents), oils other than the aforementioned process oils, dispersants, dehydrating agents, rust inhibitors, adhesion promoters, antistatic agents, fillers, lubricants, processing aids, slip agents, UV absorbers, light stabilizers, conductivity-imparting agents, antistatic agents, dispersants, flame retardants, antibacterial agents, neutralizing agents, softeners, fillers, colorants, and thermally conductive fillers. These additives are not particularly limited, and commonly used ones (known ones: for example, those described in paragraphs

[0169] to

[0174] of Japanese Patent Publication No. 5918878 and those exemplified in Japanese Patent Publication No. 2006-131663) can be used as appropriate.

[0094] The rubber composition of the present invention can exhibit excellent heat aging resistance after crosslinking. In such a rubber composition of the present invention, an antioxidant may be further used as an additive, since this can further improve heat aging resistance depending on the application. When an antioxidant is used as the additive, any known antioxidant that can be used in rubber compositions can be appropriately used. Examples of such antioxidants include hindered phenol-based compounds, aliphatic and aromatic hindered amine-based compounds, and quinoline-based compounds. The content of such antioxidants is preferably 0.1 to 10 parts by mass (more preferably 1 to 5 parts by mass) per 100 parts by mass of the uncrosslinked rubber.

[0095] The rubber composition of the present invention may contain an antioxidant as an additive. There are no particular limitations on the antioxidant, and known antioxidants can be used as appropriate, such as butylhydroxytoluene (BHT) and butylhydroxyanisole (BHA). The content of the antioxidant is preferably 0.1 to 10 parts by mass (more preferably 1 to 5 parts by mass) per 100 parts by mass of the uncrosslinked rubber.

[0096] Furthermore, the rubber composition of the present invention may contain a pigment as the additive. Such pigments are not particularly limited, and examples thereof include inorganic pigments such as titanium dioxide, zinc oxide, ultramarine, red iron oxide, lithopone, lead, cadmium, iron, cobalt, aluminum, hydrochlorides, and sulfates, and organic pigments such as azo pigments and copper phthalocyanine pigments. The content of such pigments is preferably 0.1 to 10 parts by mass, more preferably 1 to 5 parts by mass, per 100 parts by mass of the uncrosslinked rubber.

[0097] The method for producing such a rubber composition of the present invention is not particularly limited, and for example, a production method may be adopted in which the uncrosslinked rubber not having the hydrogen-bond crosslinkable moiety is mixed with the polymer component. For such mixing (kneading), a known kneading machine (e.g., kneader, pressure kneader, Banbury mixer, single-screw extruder, twin-screw extruder, etc.) can be appropriately used. Furthermore, for such mixing, the order in which each component is added and the mixing method are not particularly limited.

[0098] Furthermore, as a method for producing such a rubber composition of the present invention, it is preferable to adopt a method of obtaining the rubber composition of the present invention by mixing (kneading) a thermoplastic polymer composition containing the polymer component and the uncrosslinked rubber not having a hydrogen-bond crosslinkable moiety so that the content of the polymer component is 0.01 to 200 parts by mass per 100 parts by mass of the uncrosslinked rubber (hereinafter, for convenience, this method will be simply referred to as "production method (I)"). Such production method (I) will be briefly described below. First, the "thermoplastic polymer composition" used in production method (I) will be described.

[0099] <Thermoplastic polymer composition used in production method (I)> Such a thermoplastic polymer composition may contain the polymer component, but is not particularly limited thereto. However, from the viewpoint of enabling further improvement in mechanical properties such as compression set resistance and tensile properties, the content of the polymer component is preferably 2% by mass or more, more preferably 3% to 99% by mass, even more preferably 4% to 90% by mass, and particularly preferably 4% to 80% by mass. The thermoplastic polymer composition used in such production method (I) may contain, in addition to the polymer component, other components that can be contained in the polymer composition, as appropriate. The other components that can be contained in such a thermoplastic polymer composition are not particularly limited, but suitable examples include the above-mentioned process oil, the styrene block copolymer not having a chemically bonded crosslinking moiety, the α-olefin polymer not having a chemically bonded crosslinking moiety, the clay, and the various additives described above. Furthermore, such a thermoplastic polymer composition is more preferably one that contains, in addition to the polymer component, the process oil (more preferably paraffin oil), the styrene block copolymer that does not have a cross-linking moiety formed by chemical bonding, and the α-olefin polymer that does not have a cross-linking moiety formed by chemical bonding.

[0100] When the thermoplastic polymer composition contains process oil (more preferably paraffin oil), its content (content ratio) is not particularly limited, but it is preferably 1 to 12,000 parts by mass per 100 parts by mass of the polymer component in the thermoplastic polymer composition.

[0101] Furthermore, when the thermoplastic polymer composition contains a styrene block copolymer, its content (content ratio) is not particularly limited, but it is preferably 1 to 5,000 parts by mass per 100 parts by mass of the polymer component in the thermoplastic polymer composition.

[0102] From the viewpoint of a balance between moldability and mechanical properties, the thermoplastic polymer composition more preferably contains, in addition to the polymer component, a styrene block copolymer having no chemically bonded cross-linking moieties and a process oil (more preferably paraffin oil).

[0103] When the thermoplastic polymer composition contains an α-olefin polymer that does not have a chemically bonded cross-linking site, its content (content ratio) is not particularly limited, but it is more preferable to use it in an amount of 300 parts by mass or less (more preferably 250 parts by mass or less) per 100 parts by mass of the polymer component in the thermoplastic polymer composition.

[0104] The thermoplastic polymer composition may also contain the clay, and the content of the clay in the thermoplastic polymer composition is preferably 20 parts by mass or less, and more preferably 0.01 to 10 parts by mass, per 100 parts by mass of the polymer component.

[0105] The method for producing such a thermoplastic polymer composition is not particularly limited, and any method capable of incorporating the reaction product of the maleic anhydride graft-modified thermoplastic polymer and the crosslinking compound into the composition may be used. For example, a method similar to that described in paragraphs

[0181] to

[0215] of JP 2016-193970 A may be used, except that the "maleic anhydride graft-modified thermoplastic polymer" is used as the "polymer having a cyclic acid anhydride group in a side chain" described in the publication and the "crosslinking compound" is used as the "raw material compound" described in the publication, to react the maleic anhydride graft-modified thermoplastic polymer with the crosslinking compound to produce a thermoplastic polymer composition containing the polymer component.

[0106] Furthermore, as a method for producing such a thermoplastic polymer composition, for example, a method of mixing the maleic anhydride-grafted thermoplastic polymer, the crosslinking compound, and, if necessary, other components (the styrene block copolymer not having a chemically bonded crosslinking moiety, the process oil, the α-olefin-based polymer not having a chemically bonded crosslinking moiety, the clay, etc.) to obtain a polymer composition containing the polymer components can be preferably adopted. When such a method is used, the maleic anhydride-grafted thermoplastic polymer and the crosslinking compound can be reacted during mixing, and during this reaction, the maleic anhydride group of the maleic anhydride-grafted thermoplastic polymer can be ring-opened to form a chemical bond with the crosslinking compound, thereby efficiently forming the desired "at least one polymer component selected from the group consisting of polymer (A) and polymer (B)" depending on the type of the component.

[0107] Furthermore, when the maleic anhydride graft-modified thermoplastic polymer is reacted with the crosslinking compound by the above-mentioned method, the amount of the crosslinking compound used is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 5.0 parts by mass, per 100 parts by mass of the maleic anhydride graft-modified thermoplastic polymer. If the amount of such crosslinking compound added (amount based on parts by mass) is less than the above-mentioned lower limit, the amount of crosslinking compound is too small, so the crosslink density does not increase, and the desired physical properties tend not to be achieved. On the other hand, if the amount is more than the above-mentioned upper limit, the amount of crosslinking compound is too large, so that there are too many branches (too much crosslinking compound, so the proportion of crosslinking compound not involved in crosslinking increases), and the crosslink density tends to decrease.

[0108] In this method, the temperature conditions for reacting the maleic anhydride-grafted thermoplastic polymer with the crosslinking compound (opening the maleic anhydride group) are not particularly limited, and may be adjusted to a temperature at which they can react depending on the type of crosslinking compound. For example, from the viewpoint of softening the crosslinking compound and promoting the reaction instantaneously, a temperature of 100 to 250°C is preferred, and a temperature of 120 to 230°C is more preferred. The mixing method for carrying out this reaction is not particularly limited, and known methods such as mixing with a roll or kneader can be appropriately adopted. Furthermore, when other components are added, the order of addition of each component is not particularly limited, and may be changed appropriately depending on the types of components used.

[0109] The thermoplastic polymer composition used in the production method (I) has been explained above, and the steps of the production method (I) will now be briefly explained.

[0110] <Regarding the steps of manufacturing method (I)> In the production method (I), the thermoplastic polymer composition and the uncrosslinked rubber not having the hydrogen-bond crosslinkable moiety are mixed so that the content of the polymer component (a component in the thermoplastic polymer composition) is 0.01 to 200 parts by mass per 100 parts by mass of the uncrosslinked rubber, thereby obtaining the rubber composition of the present invention.

[0111] The method for mixing such an uncrosslinked rubber having no hydrogen-bond crosslinkable moiety with the thermoplastic polymer composition is not particularly limited, and a known method or the like can be appropriately adopted. For example, a mixing method using a Banbury mixer, a roll, a kneader, an extruder, a universal mixer, or the like can be adopted.

[0112] Furthermore, in such a mixing step, it is preferable to mix the rubber having no hydrogen-bond cross-linkable moieties with the thermoplastic polymer composition so that the content of the polymer component, which is a component of the thermoplastic polymer composition, is 0.01 to 200 parts by mass (more preferably 0.1 to 150 parts by mass, and even more preferably 1 to 100 parts by mass) per 100 parts by mass of the uncross-linked rubber having no hydrogen-bond cross-linkable moieties. If the content of such polymer component is below the lower limit, the content of the polymer component in the finally obtained rubber composition will be too low, making it impossible to obtain the rubber composition of the present invention, and even if the obtained composition is cross-linked, it will tend to be unable to exhibit sufficient performance. On the other hand, if the content of the polymer component exceeds the upper limit, the content of the polymer component in the finally obtained rubber composition will be too high, making it impossible to obtain the rubber composition of the present invention, and the physical properties of the polymer component will tend to be too pronounced in the obtained composition.

[0113] In addition, during this mixing step, it is preferable to plasticize and mix the uncrosslinked rubber not having a hydrogen-bond crosslinkable moiety and the thermoplastic polymer composition. There are no particular limitations on the method of plasticization, and any known method can be appropriately adopted. It is more preferable to mix (knead) the components at a temperature of 100 to 250°C (more preferably 120 to 230°C). If the temperature is below the lower limit, it tends to be difficult to sufficiently disperse the components (it is difficult to uniformly mix and disperse the components), while if the temperature exceeds the upper limit, deterioration tends to occur.

[0114] In the rubber composition obtained in this manner, the contents of the uncrosslinked rubber not having a hydrogen-bond crosslinkable moiety, the polymer component, and the clay are the same as the contents of each component described in the rubber composition of the present invention. When the rubber composition obtained in this manner contains the process oil, the styrene block copolymer not having a chemically bonded crosslinkable moiety, the α-olefin-based polymer not having a chemically bonded crosslinkable moiety, the clay, and the additives described above, it is preferable to appropriately adjust the contents thereof so that the final rubber composition contains the same amount as the contents of each component already described as a component of the rubber composition of the present invention. (When additives are previously added to the thermoplastic polymer composition, it is preferable to appropriately adjust the contents of the additives so that the final rubber composition contains the same amount as the contents of each component already described as a component of the rubber composition of the present invention.) In this way, by appropriately adjusting the amounts of the raw materials (components) used during the production of the rubber composition, the contents of each component can be easily adjusted as described above.

[0115] Furthermore, when preparing a rubber composition in this manner, the rubber cross-linking agent (vulcanizing agent) may further be added. The order of addition of such a rubber cross-linking agent is not particularly limited. However, from the viewpoint of obtaining a composition in an uncross-linked state, it is preferable to first mix the thermoplastic polymer composition with the uncross-linked rubber not having a hydrogen-bond cross-linkable moiety to obtain a mixture, and then add the rubber cross-linking agent to the resulting mixture and knead it under a temperature condition of 20 to 150°C (optimal temperature conditions may be selected from the temperature range appropriate for the type of rubber cross-linking agent (vulcanizing agent) and the uncross-linked rubber not having a hydrogen-bond cross-linkable moiety so as not to cause the cross-linking reaction (vulcanization reaction) to proceed). The method for kneading such a rubber cross-linking agent is not particularly limited, and known methods can be appropriately employed. For example, a method can be employed in which the rubber cross-linking agent is added to the mixture and kneaded using a kneader such as a Banbury mixer, kneader, or open roll.

[0116] The use of such a rubber composition is not particularly limited, and it can be appropriately used in known uses for which a rubber composition can be used (for example, uses of the rubber compositions described in paragraphs

[0151] to

[0152] of WO 2019 / 027022). Examples of uses for such a rubber composition include materials for producing rubber parts for daily necessities, automobile parts (e.g., rubber parts such as hoses, belts, bushings, and mounts in the engine compartment), electrical appliances, industrial parts, and the like, as well as rubber for building materials, soundproofing rubber, rubber for automobile interior materials (such as instrument panels), and rubber for tires. Furthermore, such a rubber composition can be suitably used, among others, as a material for forming rubber for building materials, soundproofing rubber, rubber for automobile interior materials (such as instrument panels), and rubber for tires.

[0117] [Crosslinked rubber composition] The crosslinked rubber composition of the present invention is a crosslinked reaction product of the above-mentioned rubber composition of the present invention, and has a Type A durometer hardness of 0 to 70 measured under a temperature condition of 20±5°C in accordance with JIS K6253-3:2012.

[0118] The method for producing such a crosslinked reaction product of a rubber composition is not particularly limited, and for example, when the rubber composition before crosslinking contains a rubber crosslinking agent (vulcanizing agent), a method can be adopted in which the rubber composition before crosslinking is appropriately heated to a temperature at which a crosslinking reaction between the uncrosslinked rubber not having a hydrogen-bond crosslinkable moiety in the composition and the rubber crosslinking agent proceeds, depending on the type and compounding ratio of the agent, and at least the uncrosslinked rubber not having a hydrogen-bond crosslinkable moiety reacts with the rubber crosslinking agent in the composition, thereby crosslinking the rubbers together. In this way, the crosslinked rubber composition of the present invention is obtained by crosslinking the above-mentioned rubber composition of the present invention, and is a composition containing a crosslinked product of the uncrosslinked rubber (crosslinked rubber: vulcanized rubber), which is a reaction product of the uncrosslinked rubber not having a hydrogen-bond crosslinkable moiety and the rubber crosslinking agent.

[0119] The crosslinked rubber composition of the present invention has a Type A durometer hardness of 0 to 70 (more preferably 0 to 65, and even more preferably 0 to 60) measured at a temperature of 20±5°C in accordance with JIS K6253-3:2012. If the Type A durometer hardness (JIS-A hardness) exceeds the upper limit, the rubber becomes too hard and the rubber elasticity decreases. Such a Type A durometer hardness (JIS-A hardness) can be easily achieved by incorporating a crosslinked product of an uncrosslinked rubber not having the above-mentioned hydrogen-bond crosslinkable moiety and the above-mentioned specific polymer component into the rubber composition (or, depending on the type of polymer component, by mixing the polymer component with other components). The Type A durometer hardness (JIS-A hardness) can be measured by a measurement method in accordance with JIS K6253-3 (JIS K6253-3:2012), published in 2012, at a temperature of 20±5°C. For example, the following measurement method can be used. That is, a 2 mm thick sheet made of a crosslinked rubber composition is first prepared, and a disk-shaped sheet having a diameter of 29 mm is punched out from this sheet. Four or more of the obtained disk-shaped sheets are stacked together so that the height (thickness) is 6.0 mm or more to prepare a measurement sample. Then, using the measurement sample and a Type A durometer (Durometer A hardness meter), the hardness is measured at five points on the surface of the measurement sample at a temperature of 20±5°C in accordance with JIS K6253-3 (published in 2012) (note that, when making such measurements, it is preferable to measure the hardness at each measurement point 3 seconds after contact of the pressure plate), and the hardness is calculated as the average of the hardness values ​​obtained at the five points.

[0120] The conditions for the crosslinking reaction to obtain a crosslinked product of the rubber composition are not particularly limited, and known conditions can be appropriately adopted. These conditions can be set appropriately depending on the type of uncrosslinked rubber not having a hydrogen-bond crosslinkable moiety in the rubber composition of the present invention, the type of rubber crosslinking agent (vulcanizing agent), and the like. For example, heating at a temperature of 20 to 230°C for 1 to 60 minutes can be used. (Regarding the temperature, an optimum temperature can be appropriately selected from the above temperature range depending on the type of rubber crosslinking agent and the type of uncrosslinked rubber not having a hydrogen-bond crosslinkable moiety so that the crosslinking reaction proceeds sufficiently.) The crosslinked product of such a rubber composition can also be prepared by allowing the crosslinking reaction to proceed while molding the composition as appropriate depending on the intended use. The molding method is also not particularly limited, and known molding methods (such as press molding using a press or cutting molding using a cutting machine) can be appropriately adopted depending on the intended use and intended design. From the viewpoint of heat aging resistance, the crosslink formed in the crosslinking reaction product of such a rubber composition is preferably a crosslink formed using a peroxide-based crosslinking agent (peroxide crosslink), and from the viewpoint of further improving physical properties (particularly elongation at break), it is preferably a crosslink formed using a sulfur-based crosslinking agent.

[0121] The crosslinked rubber composition of the present invention can be suitably used as so-called industrial rubber parts (for example, rubber parts in various automotive products, rubber parts used in industrial machinery, etc., as described in paragraph

[0157] of WO 2019 / 027022). Examples of such industrial rubber parts include daily necessities, automotive parts (for example, rubber parts such as hoses, belts, bushings, and mounts in the engine compartment), electrical appliances, industrial parts, rubber parts for building materials, soundproofing rubber, rubber for automotive interior materials (such as instrument panels), and rubber for tires. [Example]

[0122] The present invention will be described in more detail below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0123] [Maleic anhydride-modified thermoplastic polymers used in each synthesis example] Table 1 shows the abbreviations, polymer types, and properties of the maleic anhydride-modified thermoplastic polymers used in each synthesis example described below. The "maleic acid ratio" in Table 1 is a value determined using the aforementioned "method for measuring maleic acid ratio." (Note: For titration, an automatic potentiometric titrator manufactured by Kyoto Electronics Manufacturing Co., Ltd., under the trade name "AT-710M," and a 0.1 mol / L potassium hydroxide ethanol solution manufactured by Merck Ltd., under the trade name "Potassium Hydroxide Ethanol Solution," were used. The correction factor for the 0.1 mol / L potassium hydroxide ethanol solution used in this manner was 1.00, as determined from the inspection report for the solution.) The "melting point" in Table 1 is a value determined by differential scanning calorimetry (DSC) using approximately 0.01 g of each polymer at a heating rate of 10°C / min using a differential scanning calorimeter (manufactured by Hitachi High-Tech Science Corporation, under the trade name "DSC7000X").

[0124] [Table 1]

[0125] (Synthesis Examples 1 to 12) In Synthesis Examples 1 to 12, thermoplastic polymer compositions were produced by employing the "process for producing a thermoplastic polymer composition" described below, while adjusting the amount of each component used to obtain the composition shown in Table 2 below. The numerical values ​​for the composition in Table 2 below are values ​​(parts by mass) calculated based on 100 parts by mass of the amount of maleic anhydride-modified thermoplastic polymer (one of TP(1) to (7)) used in each Synthesis Example. The amount of maleic anhydride-grafted modified thermoplastic polymer used in each Synthesis Example was 4 g in Synthesis Examples 1 to 2 and 12, 8 g in Synthesis Examples 3 and 4, 60 g in Synthesis Examples 5 and 6, and 65 g in Synthesis Examples 7 to 11.

[0126] <Production Process of Thermoplastic Polymer Composition> First, a styrene-ethylene-butylene-styrene block copolymer (trade name "G1633U" manufactured by Kraton Corporation, molecular weight: 400,000 to 500,000, styrene content: 30% by mass; hereinafter, sometimes referred to as "SEBS") was placed in a pressure kneader and mixed at 180°C. While mixing, paraffin oil (trade name "300HV-S(J)" manufactured by ENEOS Corporation (formerly JXTG Nippon Oil & Energy Corporation)) was added dropwise into the pressure kneader, and the SEBS and paraffin oil were mixed for 1 minute. Next, a maleic anhydride-modified thermoplastic polymer (any of TP(1) to (7) listed in Table 1), an α-olefin-based polymer (any of an ethylene-butene copolymer (trade name "Tafmer DF7350" manufactured by Mitsui Chemicals, Inc.: hereinafter sometimes referred to as "EBM"), and a high-density polyethylene (trade name "HJ590N" manufactured by Japan Polyethylene Co., Ltd.: hereinafter sometimes referred to as "HDPE")) were further added to the pressure kneader, and the mixture was mixed (kneaded) at 180°C for 2 minutes to plasticize, thereby obtaining a mixture (A). Thereafter, the following steps (I) and (II): [Step (I)] adding a crosslinking compound directly to the mixture (A) and mixing (kneading) the mixture at 180°C for 8 minutes; [Step (II)] A step of adding clay (organic clay, trade name "ESBEN WX" manufactured by HOJUN CO., LTD.) to the mixture (A) and mixing (kneading) the mixture at 180°C for 4 minutes, and then adding a crosslinking compound and mixing (kneading) the mixture at 180°C for 8 minutes; Thermoplastic polymer compositions were produced by carrying out any one of the steps above. In Synthesis Examples 1, 3, 5, 11, and 12, step (I) was carried out after the mixture (A) was obtained, and in Synthesis Examples 2, 4, and 6 to 10, step (II) was carried out after the mixture (A) was obtained. It is clear that the reaction products of the maleic anhydride-modified thermoplastic polymer and the crosslinking compound in each Synthesis Example had a glass transition temperature of 25°C or lower, based on the type of maleic anhydride-modified thermoplastic polymer. In Synthesis Examples 5 to 11, SEBS and paraffin oil were not used, and therefore the step of mixing SEBS and paraffin oil was omitted. In Synthesis Examples 5 to 11, an α-olefin-based polymer was not used, and therefore only the maleic anhydride-modified thermoplastic polymer was added in the step of adding the maleic anhydride-modified thermoplastic polymer and the α-olefin-based polymer to the pressure kneader. Furthermore, in the above steps (I) and (II), any one of the following crosslinking compounds (1) to (3) was used as the crosslinking compound so as to have the composition shown in Table 2. Crosslinking compound (1): Benzoguanamine (trade name "Benzoguanamine" manufactured by Nippon Shokubai Co., Ltd.) Crosslinking compound (2): Tris(2-hydroxyethyl) isocyanurate (trade name "Tanac P" manufactured by Nissei Sangyo Co., Ltd.) Cross-linking compound (3): 3-amino-1,2,4-triazole (Tokyo Chemical Industry Co., Ltd.).

[0127] [Table 2]

[0128] From the types of maleic anhydride-modified thermoplastic polymers listed in Table 1 and the compositions shown in Table 2, it is clear that the thermoplastic polymer compositions (TPC(1) to (11)) obtained in Synthesis Examples 1 to 11 all contain a polymer component consisting of a reaction product of a maleic anhydride-grafted thermoplastic polymer having a maleation rate of 0.1 to 10% by mass and a crosslinking compound. On the other hand, it is clear that the thermoplastic polymer composition (TPC(12)) obtained in Synthesis Example 12 contains a copolymer-type modified maleic anhydride-modified thermoplastic polymer, and the polymer component contained in the composition consists of a reaction product of a copolymer-type maleic anhydride-modified thermoplastic polymer (comparative component) having a maleation rate of 0.1 to 10% by mass and a crosslinking compound.

[0129] Examples 1 to 8 In each of Examples 1 to 8, crosslinked rubber compositions were produced by employing the "rubber composition production process" and "crosslinked rubber composition production process" described below, while adjusting the amount of each component used so as to obtain the composition shown in Table 3. The composition values ​​in Table 3 are values ​​(parts by mass) converted based on 100 parts by mass of the uncrosslinked rubber (EPDM: ethylene-propylene-diene copolymer: product name "3092PM" manufactured by Mitsui Chemicals, Inc.) used, and the amount of uncrosslinked rubber used in each Example was 80 g.

[0130] <Production Process of Rubber Composition> First, as a component to be used in preparing the rubber composition, a powder material consisting of a mixed powder of carbon black (trade name "CB N550" manufactured by Cabot Corporation), zinc oxide as a crosslinking promoter (zinc oxide type 3 manufactured by Hakusui Tech Co., Ltd.), and stearic acid as a crosslinking promoter (manufactured by Nippon Fine Chemical Co., Ltd.) was prepared.

[0131] Next, an ethylene-propylene-diene rubber (trade name "3092PM" manufactured by Mitsui Chemicals, Inc., referred to simply as "EPDM" in the table) as an uncrosslinked rubber and a thermoplastic polymer composition (one of the thermoplastic polymer compositions (TPC(1)-(6)) obtained in Synthesis Examples 1-6) were added to a pressure kneader (trade name "Labo Plastomill" manufactured by Toyo Seiki Seisakusho, Ltd., capacity 250 mL) heated to 160°C and plasticized by kneading at 160°C and 30 rpm for 1 minute. Then, half of the powder material and the entire amount of paraffin oil were further added to the pressure kneader, and the rotation speed was changed from 30 rpm to 50 rpm. The mixture was kneaded at 160°C and 50 rpm for 1.5 minutes. The remaining half of the powder material was then further added to the pressure kneader and kneaded at 50 rpm for 1.5 minutes. Next, the ram (floating weight) was raised and lowered so that the powder material adhering to the wall surface between the material inlet and the kneading chamber of the pressure kneader was introduced into the kneading chamber, and the mixture in the kneader was kneaded for another minute at a temperature of 160°C and a rotation speed of 50 rpm. Next, the ram (floating weight) was raised and lowered again in the pressure kneader, and the mixture was kneaded for another 3 minutes at a temperature of 150°C and a rotation speed of 50 rpm, and then released to obtain a rubber composition. In this way, a rubber composition was obtained in a form that did not contain a rubber cross-linking agent (vulcanizing agent).

[0132] Next, using an open roll mill (roll size: diameter 6 inches × length 18 inches, number of rolls: 2), the rubber composition obtained as described above without a rubber crosslinking agent was kneaded with dicumyl peroxide (trade name "Percumyl D-40" manufactured by NOF Corporation, purity: 40%) as a rubber crosslinking agent to obtain a rubber composition (uncrosslinked: unvulcanized) containing a rubber crosslinking agent (hereinafter, in some cases, the kneading process of the rubber composition without a rubber crosslinking agent and dicumyl peroxide as a rubber crosslinking agent as described above will be simply referred to as the "process of obtaining a rubber composition containing a rubber crosslinking agent"). Note that the kneading conditions were room temperature (25°C), a rear roll rotation speed of 10 rpm, and a front / rear roll rotation ratio (front:rear) of 1:1.1.

[0133] <Production Process of Crosslinked Rubber Composition> 50 g of the rubber composition (uncrosslinked: unvulcanized) containing the rubber crosslinking agent obtained as described above was press-crosslinked (crosslinked (vulcanized) while press-molding) at 170°C for 10 minutes using a press molding machine (manufactured by Dumbbell Co., Ltd.) to obtain a sheet-shaped crosslinked rubber composition (a rubber sheet made of the crosslinking reaction product of the rubber composition) measuring 150 mm in length, 150 mm in width, and 2 mm in thickness.

[0134] (Comparative Examples 1 and 2) Sheet-shaped crosslinked rubber compositions were obtained in the same manner as in Example 1, except that no thermoplastic polymer composition was used and the amount of each component was adjusted so that the composition was as shown in Table 4.

[0135] (Comparative Example 3) A sheet-shaped crosslinked rubber composition was obtained in the same manner as in Example 1, except that EBM (trade name "Tafmer DF7350" manufactured by Mitsui Chemicals, Inc.) was used instead of the thermoplastic polymer composition, and the amount of each component used was adjusted so that the composition would be as shown in Table 4.

[0136] Comparative Example 4 A sheet-shaped crosslinked rubber composition was obtained in the same manner as in Example 1, except that a styrene-based thermoplastic elastomer (trade name "T320C" manufactured by Mitsubishi Chemical Corporation, JIS A hardness: 15) was used instead of the thermoplastic polymer composition, and the amount of each component used was adjusted so that the composition would be as shown in Table 4.

[0137] (Comparative Example 5) A sheet-shaped crosslinked rubber composition was obtained in the same manner as in Example 1, except that an olefin-based thermoplastic elastomer (trade name "Milastomer 6020NS" manufactured by Mitsui Chemicals, Inc., JIS A hardness: 50 (value obtained by measuring hardness 5 seconds after contact with the pressure plate)) was used instead of the thermoplastic polymer composition, and the amount of each component used was adjusted so that the composition would be as shown in Table 4.

[0138] (Comparative Example 6) A sheet-shaped crosslinked rubber composition was obtained in the same manner as in Example 1, except that the thermoplastic polymer composition (TPC (12)) obtained in Synthesis Example 12 was used as the thermoplastic polymer composition and the amount of each component used was adjusted so that the composition would be as shown in Table 4.

[0139] [Evaluation of Properties of Crosslinked Rubber Compositions Obtained in Examples 1 to 8 and Comparative Examples 1 to 6] <Hardness (JIS-A hardness) measurement> The hardness of the crosslinked rubber compositions obtained in each Example was measured as follows. First, seven disk-shaped sheets with a diameter of 29 mm were punched out from the sheet-like crosslinked rubber composition obtained as described above, to prepare four disk-shaped sheets. The four disk-shaped sheets were then stacked to a height (thickness) of 6.0 mm or more to prepare a measurement sample. Next, using a Type A durometer (Durometer A hardness meter: "Type A Durometer GSD-719K" manufactured by Teclock Corporation) at a temperature of 20±5°C, hardness was measured at five measurement points (five measurement points) on the surface of the measurement sample in accordance with JIS K6253-3 (published in 2012). The JIS A hardness was calculated by calculating the average value of the hardness values ​​at all measurement points (average of the five points). The hardness measurement at each measurement point was performed 3 seconds after the pressure plate contacted the sample. The results are shown in Tables 3 and 4, respectively.

[0140] <Measurement of 100% modulus change rate> Using each of the crosslinked rubber compositions obtained in the examples, No. 3 dumbbell-shaped test pieces were prepared in accordance with JIS K6251 (published in 2010), and a tensile test was carried out at a tensile speed of 500 mm / min to measure the 100% modulus (M100) [MPa]. This measurement was carried out using the test pieces both before and after the heat aging test described below. The 100% modulus of the test piece before the heat aging test (100% Mod before test) and the 100% modulus of the test piece after the test (100% Mod after test) were calculated using the following formula: [100% Mod change rate (%)] = {([100% Mod after test] - [100% Mod before test]) ÷ [100% Mod before test]} x 100 The rate of change in the 100% modulus (100% Mod) was calculated, and the absolute value of this rate of change was determined. The results are shown in Tables 3 and 4. The smaller the absolute value of the rate of change in 100% modulus, the more excellent the heat aging resistance (heat resistance).

[0141] (Heat aging test) For the heat aging test (accelerated aging test for measuring heat aging resistance), the No. 3 dumbbell-shaped test piece was placed in a Geer oven and heated for 72 hours under the conditions of atmospheric gas: air and temperature: 120°C, in accordance with JIS K6257 (issued in 2010).

[0142] <Test to check for oil bleeding> The occurrence of oil bleeding was confirmed using each of the crosslinked rubber compositions (2 mm thick sheets) obtained in each Example, etc., as follows. First, a sample was prepared by cutting a 2 mm thick sheet of the crosslinked rubber composition into a 1 cm square. Next, the sample (1 cm square) was placed on a piece of paper and left at room temperature for 24 hours. The sample was then removed from the paper, and the presence or absence of oil traces (remaining oil) on the paper was visually confirmed. If oil traces were found, it was determined that oil bleeding had occurred; if no oil traces were found, it was determined that oil bleeding had not occurred. The results are shown in Tables 3 and 4, respectively.

[0143] [Table 3]

[0144] [Table 4]

[0145] As is clear from the results shown in Tables 3 and 4, all of the crosslinked rubber compositions obtained in Examples 1 to 8 were free from oil bleeding and had a hardness of 58 or less. Furthermore, it was confirmed that the rate of change in 100% modulus before and after the heat aging test was 2% or less when confirmed as an absolute value for the crosslinked rubber compositions obtained in Examples 1 to 8.

[0146] In contrast, the crosslinked rubber composition obtained in Comparative Example 1 had a hardness of 60. Furthermore, when the absolute value of the change in 100% modulus of the crosslinked rubber composition obtained in Comparative Example 1 was confirmed, it was 5% before and after the heat aging test. The crosslinked rubber compositions obtained in Examples 1 to 8 and Comparative Example 1 differ in whether or not a thermoplastic polymer composition was used. Therefore, by comparing these, it was found that when any of the thermoplastic polymer compositions of TPC (1) to (6) was used (Examples 1 to 8), the hardness could be further reduced to provide a rubber system with a sufficiently low hardness, and heat aging resistance could be further improved based on the change in 100% modulus of the crosslinked rubber composition before and after the heat aging test.

[0147] The cross-linked rubber composition obtained in Comparative Example 2 contained 55 parts by mass of paraffin oil, which was 25 parts by mass more than the composition obtained in Comparative Example 1. A comparison of the compositions of Comparative Example 1 and Comparative Example 2 revealed that the cross-linked rubber composition obtained in Comparative Example 2, based on the paraffin oil content, was able to achieve a lower hardness than the cross-linked rubber composition obtained in Comparative Example 1 (the hardness value was actually lower by 5 points). However, oil bleeding occurred in the composition obtained in Comparative Example 2, and the composition was not sufficient in terms of reducing hardness without oil bleeding. Furthermore, when the absolute value of the rate of change in 100% modulus before and after the heat aging test was confirmed for the cross-linked rubber composition obtained in Comparative Example 2, the value was 8%, confirming that the heat aging resistance, measured as the rate of change in 100% modulus before and after the heat aging test, was lower than that of the cross-linked rubber composition obtained in Comparative Example 1.

[0148] The crosslinked rubber compositions obtained in Comparative Examples 3 to 5 are compositions that utilize a comparative component (thermoplastic elastomer) selected from EBM, a styrene-based thermoplastic elastomer, and an olefin-based thermoplastic elastomer. Comparing Comparative Example 1 with Comparative Examples 3 to 5, it was found that when the comparative component (thermoplastic elastomer) was utilized, it was possible to reduce the hardness compared to the crosslinked rubber composition obtained in Comparative Example 1, but the heat aging resistance, measured as the rate of change in 100% modulus before and after the heat aging test, was equal to or lower than that of the crosslinked rubber composition obtained in Comparative Example 1. Furthermore, when the evaluation results of the crosslinked rubber compositions obtained in Comparative Examples 3 to 5 are compared with the evaluation results of the crosslinked rubber compositions obtained in Examples 1 to 8, it is found that when the comparative component (thermoplastic elastomer) is used (Comparative Examples 3 to 5), it is not possible to improve the heat aging resistance based on the rate of change in 100% modulus before and after the heat aging test, whereas when any of the thermoplastic polymer compositions of TPC (1) to (6) is used (Examples 1 to 8), it is possible to improve the heat aging resistance based on the rate of change in 100% modulus before and after the heat aging test.

[0149] Furthermore, the crosslinked rubber composition obtained in Comparative Example 6 is an example in which a thermoplastic elastomer composition (TPC (12)) obtained using a copolymer type maleic anhydride-modified thermoplastic polymer, rather than a graft-modified product, was used as a comparative component. When such TPC (12) was used, it was found that the improvement in heat aging resistance, based on the rate of change in 100% modulus before and after the heat aging test, was not obtained, and oil bleeding also occurred.

[0150] From these results (shown in Tables 3 and 4), it was confirmed that the crosslinked rubber compositions obtained in Examples 1 to 8 could sufficiently suppress the occurrence of oil bleeding while enabling a lower hardness, and could further improve heat aging resistance without using an antioxidant. Furthermore, since the crosslinked rubber compositions obtained in Examples 1 to 8 did not use an antioxidant, it was also found that the occurrence of so-called "bloom (the phenomenon in which an antioxidant elutes from the composition over time)" could also be prevented.

[0151] (Examples 9 to 14) The type of EPDM of the uncrosslinked rubber was changed to "X-3012P" manufactured by Mitsui Chemicals, Inc., and in the step of obtaining a rubber composition containing a rubber crosslinking agent, instead of kneading the rubber composition not containing the rubber crosslinking agent with dicumyl peroxide as a rubber crosslinking agent, the rubber composition not containing the rubber crosslinking agent was kneaded with sulfur (oil-treated sulfur: "Kinka-jirushi Oil-Infused Fine Powder Sulfur" manufactured by Tsurumi Chemical Co., Ltd.) as a rubber crosslinking agent and a thiuram accelerator (tetrakis(2-ethylhexyl)thiuram disulfide: large) as a crosslinking accelerator. Sheet-shaped cross-linked rubber compositions were obtained in the same manner as in Example 1, except that a cross-linking accelerator (manufactured by Ouchi Shinko Chemical Co., Ltd. under the trade name "Noccelaer TOTN"), a dithiocarbamate-based cross-linking accelerator (zinc dibenzyldithiocarbamate: manufactured by Ouchi Shinko Chemical Co., Ltd. under the trade name "Noccelaer ZTC"), and a sulfenamide-based cross-linking accelerator (N-cyclohexyl-2-benzothiazylsulfenamide: manufactured by Ouchi Shinko Chemical Co., Ltd. under the trade name "Noccelaer CZ") were kneaded together, and the amounts of each component were adjusted so that the composition would be as shown in Table 5.

[0152] (Comparative Examples 7 to 8) Sheet-shaped crosslinked rubber compositions were obtained in the same manner as in Example 9, except that no thermoplastic polymer composition was used and the amount of each component was adjusted so that the composition was as shown in Table 6.

[0153] Comparative Example 9 Instead of the thermoplastic polymer composition, a styrene-based thermoplastic elastomer (trade name "T320C" manufactured by Mitsubishi Chemical Corporation, JIS A hardness: 15) was used, and a sheet-like crosslinked rubber composition was obtained in the same manner as in Example 9 except that the amounts of each component were adjusted so that the composition was the composition described in Table 6.

[0154] (Comparative Example 10) Instead of the thermoplastic polymer composition, an olefin-based thermoplastic elastomer (trade name "Millastomer 6020NS" manufactured by Mitsui Chemicals, Inc., JIS A hardness: 50 (value obtained by measuring the hardness 5 seconds after contact with the pressure plate)) was used, and a sheet-like crosslinked rubber composition was obtained in the same manner as in Example 9 except that the amounts of each component were adjusted so that the composition was the composition described in Table 6.

[0155] (Comparative Example 11) Instead of the thermoplastic polymer composition, EBM (trade name "Tufmer DF7350" manufactured by Mitsui Chemicals, Inc.) was used, and a sheet-like crosslinked rubber composition was obtained in the same manner as in Example 9 except that the amounts of each component were adjusted so that the composition was the composition described in Table 6.

[0156] (Comparative Example 12) As the thermoplastic polymer composition, the thermoplastic polymer composition (TPC(12)) obtained in Synthesis Example 12 was used, and a sheet-like crosslinked rubber composition was obtained in the same manner as in Example 9 except that the amounts of each component were adjusted so that the composition was the composition described in Table 6. <JIS-A hardness, change rate of 100% modulus, and presence or absence of oil bleed>

[0157] [Evaluation of properties of crosslinked rubber compositions obtained in Examples 9 to 14 and Comparative Examples 7 to 12] <Regarding JIS-A hardness, change rate of 100% modulus, and presence or absence of oil bleed> For the crosslinked rubber compositions obtained in Examples 9 to 14 and Comparative Examples 7 to 12, the same methods as those adopted in the above-mentioned "Evaluation of properties of crosslinked rubber compositions obtained in Examples 1 to 8 and Comparative Examples 1 to 6" were adopted to measure the JIS-A hardness and the change rate of 100% modulus, and to confirm the presence or absence of oil bleed. The obtained results are shown in Tables 5 and 6, respectively.

[0158] <Measurement of the rate of change in breaking strength and the rate of change in breaking elongation> Using each of the crosslinked rubber compositions obtained in the examples, No. 3 dumbbell-shaped test pieces were prepared in accordance with JIS K6251 (published in 2010), and a tensile test was carried out at a tensile speed of 500 mm / min to measure the breaking strength (TB [unit: MPa]) and breaking elongation (EB [unit: %]). These measurements were carried out using the test pieces both before and after the heat aging test.

[0159] The rate of change in breaking strength was calculated from the breaking strength of the test piece before the heat aging test (breaking strength before the test) and the breaking strength of the test piece after the heat aging test (breaking strength after the test) using the following formula: [Rate of change in breaking strength (%)] = {([Breaking strength after test] - [Breaking strength before test]) ÷ [Breaking strength before test]} × 100 The rate of change in breaking elongation was calculated from the breaking elongation of the test piece before the heat aging test (breaking elongation before the test) and the breaking elongation of the test piece after the heat aging test (breaking elongation after the test) using the following formula: [Rate of change in breaking elongation (%)] = {([Breaking elongation after test] - [Breaking elongation before test]) ÷ [Breaking elongation before test]} × 100 The absolute values ​​of these rates of change are shown in Tables 5 and 6, respectively.

[0160] [Table 5]

[0161] [Table 6]

[0162] As is clear from the results shown in Tables 5 and 6, all of the crosslinked rubber compositions obtained in Examples 9 to 14 did not suffer from oil bleeding and had a hardness of 68 or less. Furthermore, when the absolute value of the rate of change in 100% modulus before and after the heat aging test was confirmed, all of the crosslinked rubber compositions obtained in Examples 9 to 14 had a value of 4% or less.

[0163] In contrast, the crosslinked rubber composition obtained in Comparative Example 7 had a hardness of 70. Furthermore, when the absolute value of the rate of change in 100% modulus of the crosslinked rubber composition obtained in Comparative Example 7 before and after the heat aging test was confirmed, the value was 5%. The crosslinked rubber compositions obtained in Examples 9 to 14 and the crosslinked rubber composition obtained in Comparative Example 7 differ in whether or not a thermoplastic polymer composition is used. By comparing these, it was found that when any of the thermoplastic polymer compositions of TPC (1) to (6) was used (Examples 9 to 14), the hardness could be further reduced to a sufficiently low level in the rubber system, and the heat aging resistance could be further improved based on the rate of change in 100% modulus before and after the heat aging test.

[0164] The cross-linked rubber composition obtained in Comparative Example 8 contained 80 parts by mass of paraffin oil, which was 50 parts by mass more than the composition obtained in Comparative Example 7. A comparison of the compositions of Comparative Examples 7 and 8 revealed that the cross-linked rubber composition obtained in Comparative Example 8 was able to achieve a lower hardness than the cross-linked rubber composition obtained in Comparative Example 7 based on the paraffin oil content (the hardness value was actually lower by 8 points). However, oil bleeding occurred in the composition obtained in Comparative Example 8, and the composition was not sufficient in terms of reducing hardness without oil bleeding. Furthermore, when the absolute value of the rate of change in 100% modulus before and after the heat aging test was confirmed for the cross-linked rubber composition obtained in Comparative Example 8, the value was 7%, confirming that the heat aging resistance was lower than that of the cross-linked rubber composition obtained in Comparative Example 7.

[0165] The crosslinked rubber compositions obtained in Comparative Examples 9 to 11 are compositions that use a comparative component (thermoplastic elastomer) selected from a styrene-based thermoplastic elastomer, an olefin-based thermoplastic elastomer, and EBM instead of a thermoplastic polymer composition. A comparison of Comparative Example 7 with Comparative Examples 9 to 11 reveals that, although the use of the comparative component (thermoplastic elastomer) makes it possible to reduce the hardness compared to the crosslinked rubber composition obtained in Comparative Example 7, the heat aging resistance, measured as the rate of change in 100% modulus before and after a heat aging test, is lower than that of the crosslinked rubber composition obtained in Comparative Example 7.

[0166] Furthermore, the crosslinked rubber composition obtained in Comparative Example 12 was not a graft-modified product, but a thermoplastic elastomer composition (TPC(12)) obtained by using a copolymer type maleic anhydride-modified thermoplastic polymer. However, even when such TPC(12) was used, it was found that the improvement effect of heat aging resistance based on the rate of change in 100% modulus before and after the heat aging test was not obtained, and oil bleeding occurred.

[0167] From these results (shown in Tables 5 and 6), it was confirmed that the crosslinked rubber compositions obtained in Examples 9 to 14 were able to sufficiently suppress the occurrence of oil bleeding while making it possible to achieve a sufficiently low hardness, and furthermore, were able to further improve heat aging resistance without using an antioxidant. Furthermore, since the crosslinked rubber compositions obtained in Examples 9 to 14 did not use an antioxidant, it was also found that the occurrence of so-called "bloom" (the phenomenon in which an antioxidant elutes from a composition over time) could also be prevented.

[0168] Furthermore, for all of the crosslinked rubber compositions obtained in Examples 9 to 14, when the absolute rate of change in breaking strength before and after the heat aging test was determined, the value was 2% or less, whereas for all of the crosslinked rubber compositions obtained in Comparative Examples 7 to 12, when the absolute rate of change in breaking strength before and after the heat aging test was determined, the value was 4% or more. Furthermore, for all of the crosslinked rubber compositions obtained in Examples 9 to 14, when the absolute rate of change in breaking elongation before and after the heat aging test was determined, the value was 6% or less, whereas for all of the crosslinked rubber compositions obtained in Comparative Examples 7 to 12, when the absolute rate of change in breaking elongation before and after the heat aging test was determined, the value was 7% or more. From the perspectives of the rate of change in breaking strength and the rate of change in breaking elongation, it was found that the crosslinked rubber compositions obtained in Examples 9 to 14 had higher heat aging resistance than the crosslinked rubber compositions obtained in Comparative Examples 7 to 12.

[0169] (Examples 15 to 18) Styrene butadiene rubber (trade name "Nipol 1502" manufactured by Nippon Zeon Co., Ltd., hereinafter sometimes referred to as "SBR") was used instead of EPDM, and any of the thermoplastic polymer compositions (TPC (1) to (3) and (5)) obtained in Synthesis Examples 1 to 3 and 5 was used as the thermoplastic polymer composition, and carbon black and paraffin oil were not used. In the step of obtaining a rubber composition containing a rubber crosslinking agent, instead of kneading the rubber composition not containing a rubber crosslinking agent with dicumyl peroxide as the rubber crosslinking agent, the rubber composition not containing a rubber crosslinking agent was kneaded with sulfur (oil-treated sulfur: trade name "Kinkaji Oil-Filled Fine Sulfur" manufactured by Tsurumi Chemical Co., Ltd.) as the rubber crosslinking agent and a crosslinking accelerator. A sulfenamide-based accelerator (N-cyclohexyl-2-benzothiazylsulfenamide, manufactured by Ouchi Shinko Chemical Co., Ltd. under the trade name "Noccela CZ") serving as a crosslinking accelerator, a guanidine-based accelerator (1,3-diphenylguanidine, manufactured by Ouchi Shinko Chemical Co., Ltd. under the trade name "Noccela D") serving as a crosslinking accelerator, and an aromatic amine-based antioxidant (N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine, manufactured by Ouchi Shinko Chemical Co., Ltd. under the trade name "Nocrac 6C") serving as an antioxidant were kneaded together, and the amounts of each component were adjusted so that the composition would be as shown in Table 7. The same procedures as in Example 1 were repeated to obtain crosslinked rubber compositions in sheet form.

[0170] Example 19 A sheet-shaped crosslinked rubber composition was obtained in the same manner as in Example 15, except that natural rubber (NR:RSS No. 3, manufactured in Thailand) was used instead of styrene-butadiene rubber (trade name "Nipol 1502" manufactured by Nippon Zeon Co., Ltd., hereinafter sometimes referred to as "SBR").

[0171] (Comparative Example 13) A sheet-shaped crosslinked rubber composition was obtained in the same manner as in Example 15, except that no thermoplastic polymer composition was used and the amount of each component used was adjusted so that the composition would be as shown in Table 8.

[0172] (Comparative Example 14) A sheet-shaped cross-linked rubber composition was obtained in the same manner as in Example 15, except that no thermoplastic polymer composition was used, and aroma oil (trade name "T-DAE Oil" manufactured by ENEOS Corporation (formerly JXTG Energy Corporation)) was added together with the powder material at the same time as adding the powder material, and the amount of each component used was adjusted so that the composition would be as shown in Table 8.

[0173] (Comparative Example 15) A sheet-shaped crosslinked rubber composition was obtained in the same manner as in Example 19, except that no thermoplastic polymer composition was used and the amount of each component used was adjusted so that the composition would be as shown in Table 8.

[0174] (Comparative Example 16) A sheet-shaped cross-linked rubber composition was obtained in the same manner as in Example 19, except that no thermoplastic polymer composition was used, and aroma oil (trade name "T-DAE Oil" manufactured by ENEOS Corporation (formerly JXTG Energy Corporation)) was added together with the powder material at the same time as adding the powder material, and the amount of each component used was adjusted so that the composition would be as shown in Table 8.

[0175] (Comparative Example 17) A sheet-shaped crosslinked rubber composition was obtained in the same manner as in Example 15, except that a styrene-based thermoplastic elastomer (trade name "T320C" manufactured by Mitsubishi Chemical Corporation, JIS A hardness: 15) was used instead of the thermoplastic polymer composition, and the amount of each component used was adjusted so that the composition would be as shown in Table 8.

[0176] (Comparative Example 18) A sheet-shaped crosslinked rubber composition was obtained in the same manner as in Example 15, except that an olefin-based thermoplastic elastomer (trade name "Milastomer 6020NS" manufactured by Mitsui Chemicals, Inc., JIS A hardness: 50 (value obtained by measuring hardness 5 seconds after contact with the pressure plate)) was used instead of the thermoplastic polymer composition, and the amount of each component used was adjusted so that the composition would be as shown in Table 8.

[0177] (Comparative Example 19) Instead of using the thermoplastic polymer composition, EBM (trade name "Tufmer DF7350" manufactured by Mitsui Chemicals, Inc.) was used, and a sheet-like crosslinked rubber composition was obtained in the same manner as in Example 19, except that the amounts of each component were adjusted so that the composition became the composition described in Table 8.

[0178] [Evaluation of the properties of the crosslinked rubber compositions obtained in Examples 15 to 19 and Comparative Examples 13 to 19] <Regarding the measurement of JIS-A hardness, change rate of 100% modulus, change rate of breaking strength, change rate of elongation at break, and presence or absence of oil bleed> For the crosslinked rubber compositions obtained in Examples 15 to 19 and Comparative Examples 13 to 19, the same methods as those employed in the above-mentioned "Evaluation of the properties of the crosslinked rubber compositions obtained in Examples 9 to 14 and Comparative Examples 7 to 12" were used to measure the JIS-A hardness, change rate of 100% modulus, change rate of breaking strength, and change rate of elongation at break, and to confirm the presence or absence of oil bleed. The obtained results are shown in Tables 7 and 8, respectively.

[0179]

Table 7

[0180]

Table 8

[0181] As is also clear from the results shown in Tables 7 to 8, all of the crosslinked rubber compositions obtained in Examples 15 to 18 of the system using SBR as the uncrosslinked rubber had no oil bleed, and moreover, had a hardness of 43 or less. In addition, all of the crosslinked rubber compositions obtained in Examples 15 to 18 of the system using SBR as the uncrosslinked rubber had a change rate of 100% modulus of 9.7% or less in absolute value before and after the heat aging test.

[0182] In contrast, the crosslinked rubber composition obtained in Comparative Example 13, which used SBR as the uncrosslinked rubber, had a hardness of 46. Furthermore, when the absolute value of the rate of change in 100% modulus of the crosslinked rubber composition obtained in Comparative Example 13 before and after the heat aging test was confirmed, the value was 23.4%. The crosslinked rubber compositions obtained in Examples 15 to 18 and the crosslinked rubber composition obtained in Comparative Example 13 differ in the presence or absence of a thermoplastic polymer composition. Therefore, by comparing these, it was found that when any of the thermoplastic polymer compositions of TPC (1) to (3) and (5) was used (Examples 15 to 18), the hardness could be further reduced to a sufficiently low level in such a rubber system, and the heat aging resistance, based on the rate of change in 100% modulus before and after the heat aging test, could be further improved.

[0183] The crosslinked rubber composition obtained in Comparative Example 14 differs from the composition obtained in Comparative Example 13 in that it contains 50 parts by mass of aromatic oil. Comparing these compositions, it was found that the use of aromatic oil, as in the crosslinked rubber composition obtained in Comparative Example 14, can reduce hardness (the hardness actually decreased by 12 points), but oil bleeding occurs. The results of the crosslinked rubber composition obtained in Comparative Example 14 also showed that the use of aromatic oil alone cannot reduce hardness without causing oil bleeding. Furthermore, when the absolute value of the change in 100% modulus of the crosslinked rubber composition obtained in Comparative Example 14 before and after the heat aging test was confirmed, the value was 27.8%, confirming that the crosslinked rubber composition obtained in Comparative Example 14 had lower heat aging resistance than the crosslinked rubber composition obtained in Comparative Example 13.

[0184] The cross-linked rubber compositions obtained in Comparative Examples 17 to 18 were compositions that utilized a comparative component (thermoplastic elastomer) selected from a styrene-based thermoplastic elastomer and an olefin-based thermoplastic elastomer instead of a thermoplastic polymer composition. Due to the use of such a comparative component (thermoplastic elastomer), the cross-linked rubber compositions obtained in Comparative Examples 17 to 18 had lower hardness than the cross-linked rubber composition obtained in Comparative Example 13. Comparing the cross-linked rubber compositions obtained in Examples 15 to 18 with those obtained in Comparative Examples 17 to 18, it was found that the cross-linked rubber compositions in Comparative Examples 17 to 18 differed in composition in that they utilized a comparative component (thermoplastic elastomer) instead of a thermoplastic polymer composition. However, when such a comparative component was utilized, it was found that the effect of improving heat aging resistance, measured as the rate of change in 100% modulus before and after a heat aging test, was not sufficiently achieved compared to the case where a thermoplastic polymer composition was utilized.

[0185] These results (shown in Tables 7 and 8) confirm that the crosslinked rubber compositions obtained in Examples 15 to 18, which used SBR as the uncrosslinked rubber, were able to sufficiently reduce hardness while sufficiently suppressing the occurrence of oil bleeding and further improving heat aging resistance. In Examples 15 to 18 and Comparative Examples 13 to 14 and 17 to 18, 1.0 part by mass of antioxidant was used per 100 parts by mass of SBR during the preparation of the compositions. Even when comparing systems containing equal amounts of such antioxidants, the crosslinked rubber compositions obtained in Examples 15 to 18 showed improved heat aging resistance, as described above.

[0186] Furthermore, as is clear from the results shown in Tables 7 and 8, the crosslinked rubber compositions obtained in Example 19, which used NR as the uncrosslinked rubber, did not exhibit oil bleeding and had a hardness of 33. Furthermore, for all of the crosslinked rubber compositions obtained in Example 19, which used NR as the uncrosslinked rubber, the absolute value of the rate of change in 100% modulus before and after the heat aging test was 10.2%.

[0187] In contrast, the crosslinked rubber composition obtained in Comparative Example 15, which used NR as the uncrosslinked rubber, had a hardness of 41. Furthermore, when the absolute value of the rate of change in 100% modulus of the crosslinked rubber composition obtained in Comparative Example 15 was confirmed before and after the heat aging test, the value was 25.9%. The crosslinked rubber composition obtained in Example 19 and the crosslinked rubber composition obtained in Comparative Example 15 differ in the presence or absence of a thermoplastic polymer composition (TPC (1)). Therefore, by comparing these, it was found that when TPC (1) was used (Example 19), it was possible to further reduce the hardness of the crosslinked rubber composition and further improve the heat aging resistance.

[0188] Furthermore, the crosslinked rubber composition obtained in Comparative Example 16 differs in composition from the composition obtained in Comparative Example 15 in that it contains 50 parts by mass of aromatic oil. Comparing these compositions, it was found that when aromatic oil is used as in the crosslinked rubber composition obtained in Comparative Example 16, it is possible to reduce hardness (the hardness value actually decreased by 10 points), but oil bleeding occurs. From the results of the crosslinked rubber composition obtained in Comparative Example 16, it was found that the use of aromatic oil alone is not enough to reduce hardness without causing oil bleeding.

[0189] In addition, the crosslinked rubber composition obtained in Comparative Example 19, which uses NR as the uncrosslinked rubber, is a composition different in composition from the crosslinked rubber composition obtained in Example 19 in that EBM is used as a comparative component instead of TPC (1). However, the crosslinked rubber composition obtained in Comparative Example 19 had a hardness of 38, and when the absolute value of the rate of change in 100% modulus before and after the heat aging test was confirmed, the value was 34%. Here, by comparing the crosslinked rubber composition obtained in Example 19 with the crosslinked rubber composition obtained in Comparative Example 19, it was found that when TPC (1) was used (Example 19), it was possible to further reduce the hardness of the crosslinked rubber composition and further improve the heat aging resistance compared to when EBM was used as a comparative component (Comparative Example 19).

[0190] From these results (shown in Tables 7 and 8), it was confirmed that the crosslinked rubber composition obtained in Example 19, which uses NR as the uncrosslinked rubber, can reduce hardness while sufficiently suppressing the occurrence of oil bleeding and further improve heat aging resistance. Note that in Example 19 and Comparative Examples 15-16 and 19, 1.0 part by mass of antioxidant was used per 100 parts by mass of NR when preparing the compositions. Even when comparing systems containing equal amounts of antioxidant, it was found that the heat aging resistance of the crosslinked rubber composition obtained in Example 19 was improved, as described above.

[0191] Furthermore, when the absolute value of the rate of change in breaking strength before and after the heat aging test was confirmed for the crosslinked rubber compositions obtained in Examples 15 to 19, the value was 9.7% or less, whereas when the absolute value of the rate of change in breaking strength before and after the heat aging test was confirmed for all of the crosslinked rubber compositions obtained in Comparative Examples 13 to 19, the value was 22.5% or more. Furthermore, when the absolute value of the rate of change in breaking elongation before and after the heat aging test was confirmed for all of the crosslinked rubber compositions obtained in Examples 15 to 19, the value was 8.3% or less, whereas when the absolute value of the rate of change in breaking elongation before and after the heat aging test was confirmed for all of the crosslinked rubber compositions obtained in Comparative Examples 13 to 19, the value was 28.6% or more. From these results of the rate of change in breaking strength and rate of change in breaking elongation, it was found that when the crosslinked rubber compositions obtained in Examples 15 to 18 were compared with the crosslinked rubber compositions obtained in Comparative Examples 13 to 14 and 17 to 18, and when the crosslinked rubber composition obtained in Example 19 was compared with the crosslinked rubber compositions obtained in Comparative Examples 15 to 16 and 19, the crosslinked rubber compositions obtained in the Examples had higher heat aging resistance than the crosslinked rubber compositions obtained in the Comparative Examples.

[0192] (Examples 20 to 21) Styrene butadiene rubber (trade name "Nipol 1502" manufactured by Nippon Zeon Corporation, hereinafter sometimes referred to as "SBR") was used instead of EPDM, the type of thermoplastic polymer composition was changed to one of the thermoplastic polymer compositions (TPC(7) to (8)) obtained in Synthesis Examples 7 to 8, silica (trade name "AQ" manufactured by Tosoh Silica Corporation) was used instead of carbon black, aromatic oil (trade name "T-DAE Oil" manufactured by ENEOS Corporation) was used instead of paraffin oil, and instead of adding half (half) of the powder material and the entire amount of paraffin oil, half (half) of the powder material, the entire amount of aromatic oil, and a silane coupling agent (Evonik In the process of obtaining a rubber composition containing a rubber crosslinking agent by adding a rubber composition containing a rubber crosslinking agent (product name "Si-69" manufactured by Industries AG) and a crosslinking agent for rubber, instead of kneading the rubber composition not containing a rubber crosslinking agent with dicumyl peroxide as a rubber crosslinking agent, a rubber composition not containing a rubber crosslinking agent is kneaded with sulfur (oil-treated sulfur: product name "Kinka-jirushi oil-infused fine powder sulfur" manufactured by Tsurumi Chemical Co., Ltd.) as a rubber crosslinking agent and a sulfenamide-based crosslinking accelerator (N-cyclohexyl-2-benzothiazyl sulfenamide: Ouchi Shin Co., Ltd.) as a crosslinking accelerator. Sheet-shaped cross-linked rubber compositions were obtained in the same manner as in Example 1, except that a cross-linking accelerator (manufactured by Ouchi Shinko Chemical Co., Ltd. under the trade name "Noccela CZ"), a guanidine-based cross-linking accelerator (1,3-diphenylguanidine, manufactured by Ouchi Shinko Chemical Co., Ltd. under the trade name "Noccela D"), and an aromatic amine-based antiaging agent (N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine, manufactured by Ouchi Shinko Chemical Co., Ltd. under the trade name "Nocrac 6C") were mixed together, and the amounts of each component were adjusted so that the composition would be as shown in Table 9.

[0193] (Comparative Example 20) A sheet-shaped crosslinked rubber composition was obtained in the same manner as in Example 20, except that a styrene-based thermoplastic elastomer (trade name "M1943" manufactured by Asahi Kasei Corporation, JIS A hardness: 67) was used instead of the thermoplastic polymer composition, and the amount of each component used was adjusted so that the composition would be as shown in Table 9.

[0194] [Evaluation of the properties of the crosslinked rubber compositions obtained in Examples 20-21 and Comparative Example 20] <Measurement of JIS-A hardness> For the crosslinked rubber compositions obtained in Examples 20-21 and Comparative Example 20, the JIS-A hardness was measured in the same manner as the method adopted in the above-mentioned "[Evaluation of the properties of the crosslinked rubber compositions obtained in Examples 1-8 and Comparative Examples 1-6]". The obtained results are shown in Table 9.

[0195] <Measurement of loss tangent (tanδ), an index related to viscoelasticity> Using the sheet-like crosslinked rubber compositions (rubber sheets) obtained in Examples 20-21 and Comparative Example 20, respectively, in accordance with JIS K-6394 (issued in 2007), tanδ at 0 °C and tanδ at 60 °C were measured. That is, for the rubber sheet, using a viscoelasticity measuring device (trade name "REOGEL E-4000" manufactured by UBM), in accordance with JIS K 6394, the measurement temperature was changed from -10 °C to 60 °C under the conditions of strain: 20 μm (0.1%) and frequency: 10 Hz for measurement, and tanδ [tanδ(0 °C)] at 0 °C and tanδ [tanδ(60 °C)] at 60 °C were obtained respectively, and the balance (tanδ(0 °C) / tanδ(60 °C)) between the two was obtained from the measured values. The measurement results are shown in Table 9. The values of tanδ(0 °C) and tanδ(60 °C) shown in Table 9 are relative values when the values of tanδ(0 °C) and tanδ(60 °C) of the sheet-like crosslinked rubber composition (rubber sheet) obtained in Comparative Example 20 were each converted to 100. It should be noted that when manufacturing a tire, it can be said that the wet grip performance is better as the numerical value of tanδ under the condition of a measurement temperature of 0 °C is larger, and it can be said that the low fuel consumption (rolling resistance) is better as the numerical value of tanδ under the condition of a measurement temperature of 60 °C is smaller.

[0196]

Table 9

[0197] As is clear from the results shown in Table 9, the crosslinked rubber compositions obtained in Examples 20-21 and Comparative Example 20 differ only in that Examples 20-21 utilize a thermoplastic polymer composition, while Comparative Example 20 utilizes a comparative component of a thermoplastic polymer composition. Comparing these, it was confirmed that when either the thermoplastic polymer composition of TPC (7) or (8) was utilized (Examples 20-21), the hardness was lower than when a styrene-based thermoplastic elastomer was utilized. Therefore, it was found that in rubber systems utilizing the thermoplastic polymer compositions described in Examples 20-21, it was possible to achieve sufficiently low hardness.

[0198] Furthermore, it was found that the cross-linked rubber compositions obtained in Examples 20 to 21, which utilize a thermoplastic polymer composition, have a larger tan δ(0°C) value and a smaller tan δ(60°C) value compared to the case where a styrene-based thermoplastic elastomer was used (Comparative Example 20), resulting in a better balance between the two (tan δ(0°C) / tan δ(60°C)).

[0199] (Examples 22 to 23) Sheet-shaped crosslinked rubber compositions were obtained in the same manner as in Example 20, except that the type of thermoplastic polymer composition was changed to one of the thermoplastic polymer compositions (TPC(9) to (10)) obtained in Synthesis Examples 9 to 10, no aroma oil was used, and the amount of each component used was adjusted so that the composition was as shown in Table 10.

[0200] (Comparative Examples 21 to 22) Sheet-shaped crosslinked rubber compositions were obtained in the same manner as in Example 20, except that no thermoplastic polymer composition was used and the amount of each component was adjusted so that the composition was as shown in Table 10.

[0201] [Evaluation of Properties of Crosslinked Rubber Compositions Obtained in Examples 22 to 23 and Comparative Examples 21 to 22] <Measurement of JIS-A Hardness and Loss Tangent (tanδ)> For the crosslinked rubber compositions obtained in Examples 22 to 23 and Comparative Examples 21 to 22, the same method as that adopted in the above-mentioned "Evaluation of the Properties of the Crosslinked Rubber Compositions Obtained in Examples 20 to 21 and Comparative Example 20" was adopted to measure the JIS-A hardness and the loss tangent (tanδ). The obtained results are shown in Table 10. The values of tanδ(0°C) and tanδ(60°C) shown in Table 10 are relative values when the values of tanδ(0°C) and tanδ(60°C) of the sheet-like crosslinked rubber composition (rubber sheet) obtained in Comparative Example 21 are each converted to 100.

[0202]

Table 10

[0203] As is clear from the results shown in Table 10, when comparing the compositions of the crosslinked rubber compositions obtained in Examples 22 to 23 with those of the crosslinked rubber compositions obtained in Comparative Examples 21 to 22, in Comparative Examples 21 to 22, the composition is different in that an aroma oil is used instead of the thermoplastic polymer composition used in Examples 22 to 23. Therefore, when comparing these, it was confirmed that when using either of the thermoplastic polymer compositions of TPC(9) and (10) (Examples 22 to 23), the hardness becomes a lower value even when compared with the case of using "aroma oil" instead of the thermoplastic polymer composition. Therefore, it was found that in a rubber system using the thermoplastic polymer composition as described in Examples 22 to 23, it is possible to make the hardness sufficiently low.

[0204] Furthermore, the crosslinked rubber compositions obtained in Examples 22 to 23 using the thermoplastic polymer composition have a larger value of tanδ(0°C) and a smaller value of tanδ(60°C) compared with the case of using a styrenic thermoplastic elastomer (Comparative Examples 21 to 22), and it was also found that the balance between the two (tanδ(0°C) / tanδ(60°C)) is higher.

[0205] Example 24 Styrene butadiene rubber (trade name "Nipol 1502" manufactured by Zeon Corporation, hereinafter sometimes referred to as "SBR") was used instead of EPDM, the type of thermoplastic polymer composition was changed to the thermoplastic polymer composition obtained in Synthesis Example 11 (TPC (11)), silica (trade name "AQ" manufactured by Tosoh Silica Corporation) was used instead of carbon black, aromatic oil (trade name "T-DAE Oil" manufactured by ENEOS Corporation) was used instead of paraffin oil, and instead of preparing a powder material consisting of a mixed powder of carbon black, zinc oxide, and stearic acid, a powder material consisting of a mixed powder of silica, zinc oxide, stearic acid, and an antioxidant (aromatic amine-based antioxidant: N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine: trade name "Nocrac 6C" manufactured by Ouchi Shinko Chemical Co., Ltd.) was prepared, and instead of adding half (half) of the powder material and the entire amount of paraffin oil, half (half) of the powder material, the entire amount of the aromatic oil, and a silane coupling agent (Evonik In the step of adding a rubber composition containing a rubber crosslinking agent, instead of kneading the rubber composition not containing the rubber crosslinking agent with dicumyl peroxide as the rubber crosslinking agent, the rubber composition not containing the rubber crosslinking agent was kneaded with sulfur (oil-treated sulfur: trade name "Kinka-jirushi Oil-Infused Fine Sulfur" manufactured by Tsurumi Chemical Co., Ltd.) as a rubber crosslinking agent, a sulfenamide-based crosslinking accelerator (N-cyclohexyl-2-benzothiazylsulfenamide: trade name "Noccela CZ" manufactured by Ouchi Shinko Chemical Co., Ltd.), and a guanidine-based crosslinking accelerator (1,3-diphenylguanidine, trade name "Noccela D" manufactured by Ouchi Shinko Chemical Co., Ltd.), and the amounts of each component were adjusted so that the composition would be as shown in Table 11. A sheet-shaped crosslinked rubber composition was obtained in the same manner as in Example 1.

[0206] (Comparative Example 23) Instead of the thermoplastic polymer composition, a styrene-based thermoplastic elastomer (trade name "Tuftec H1052" manufactured by Asahi Kasei Corporation, JIS A hardness: 67) was used, and a sheet-like crosslinked rubber composition was obtained in the same manner as in Example 24, except that the amounts of each component were adjusted so that the composition became the composition described in Table 11.

[0207] [Evaluation of the properties of the crosslinked rubber compositions obtained in Example 24 and Comparative Example 23] <Regarding the measurement of JIS-A hardness and loss tangent (tanδ)>[ For the crosslinked rubber compositions obtained in Example 24 and Comparative Example 23, the same method as the method adopted in the above-mentioned "Evaluation of the properties of the crosslinked rubber compositions obtained in Examples 20 to 21 and Comparative Example 20" was adopted to measure the JIS-A hardness and loss tangent (tanδ). The obtained results are shown in Table 11. The values of tanδ(0°C) and tanδ(60°C) shown in Table 11 are relative values when the values of tanδ(0°C) and tanδ(60°C) of the sheet-like crosslinked rubber composition (rubber sheet) obtained in Comparative Example 23 are each converted to 100.

[0208] <Measurement of the change rate of 100% modulus>[ Using the crosslinked rubber compositions obtained in Example 24 and Comparative Example 23 respectively, in accordance with JIS K6251 (issued in 2010), dumbbell No. 3-shaped test pieces were prepared and a tensile test was conducted at a tensile speed of 500 mm / min to measure the 100% modulus (M100) [MPa]. The obtained results are shown in Table ll.

[0209]

Table 11

[0210] As is clear from the results shown in Table 11, the crosslinked rubber composition obtained in Example 24 and the crosslinked rubber composition obtained in Comparative Example 23 differ only in that Example 24 uses a thermoplastic polymer composition, while Comparative Example 23 uses a comparative component of a thermoplastic polymer composition. Comparing these, it was confirmed that when the thermoplastic polymer composition was used (Example 24), the hardness was lower than when a styrene-based thermoplastic elastomer was used (Comparative Example 23). Furthermore, the 100% modulus value also revealed that when the thermoplastic polymer composition was used (Example 24), the flexibility was higher than when a styrene-based thermoplastic elastomer was used (Comparative Example 23). These results demonstrate that a rubber system using a thermoplastic polymer composition such as that described in Example 24 can achieve a sufficiently low hardness.

[0211] Furthermore, it was found that the cross-linked rubber composition obtained in Example 24, which utilized a thermoplastic polymer composition, had a larger tan δ(0°C) value and a smaller tan δ(60°C) value compared to the case where a styrene-based thermoplastic elastomer was used (Comparative Example 23), and that the balance between the two (tan δ(0°C) / tan δ(60°C)) was better. [Industrial Applicability]

[0212] As described above, the present invention makes it possible to provide a rubber composition that, after crosslinking (vulcanization), has a sufficiently low hardness, can sufficiently prevent the occurrence of oil bleeding, and can exhibit excellent heat aging resistance, and a crosslinked rubber composition that is the crosslinking reaction product thereof. Because the rubber composition of the present invention can exhibit the above-mentioned excellent properties after crosslinking, it is particularly useful as a material for daily necessities, automobile parts (e.g., rubber parts in the engine room, such as hoses, belts, bushings, and mounts), electrical appliances, industrial parts, rubber parts for building materials, soundproofing rubber, rubber for automobile interior materials (such as instrument panels), and rubber for tires.

Claims

1. an uncrosslinked rubber having no hydrogen-bond crosslinkable site; at least one polymer component selected from the group consisting of a polymer (A) having a side chain (a) containing a hydrogen-bond cross-linkable moiety having a carbonyl-containing group and / or a nitrogen-containing heterocycle and having a glass transition point of 25°C or lower, and a polymer (B) having a side chain containing a hydrogen-bond cross-linkable moiety and a covalent-bond cross-linking moiety and having a glass transition point of 25°C or lower; a rubber crosslinking agent; and the uncrosslinked rubber is at least one selected from the group consisting of diene rubbers having no hydrogen-bond crosslinkable moiety and hydrogenated products thereof, The content of the polymer component is 0.01 to 200 parts by mass per 100 parts by mass of the uncrosslinked rubber, and The rubber composition, wherein the polymer (A) and the polymer (B) are both reaction products of a maleic anhydride-grafted thermoplastic polymer having a maleic acid content of 0.1 to 10% by mass and a crosslinking compound.

2. 2. The rubber composition according to claim 1, wherein the crosslinking compound is a compound having at least one of a hydroxyl group, an amino group, an imino group, and a thiol group.

3. 3. The rubber composition according to claim 1, wherein the maleic anhydride-grafted thermoplastic polymer is a polyolefin-based polymer grafted with maleic anhydride and / or a diene-based polymer grafted with maleic anhydride.

4. The rubber composition according to any one of claims 1 to 3, wherein the maleic anhydride graft-modified thermoplastic polymer is a maleic anhydride graft-modified product of at least one thermoplastic polymer selected from the group consisting of polypropylene, polyethylene, ethylene-butene copolymer, ethylene-propylene copolymer, ethylene-octene copolymer, and ethylene-propylene-diene copolymer.

5. The rubber composition according to any one of claims 1 to 4, further comprising clay.

6. The uncrosslinked rubber is at least one diene rubber selected from the group consisting of natural rubber, styrene-butadiene rubber, and ethylene-propylene-diene rubber. The rubber composition according to any one of claims 1 to 5.

7. A crosslinked rubber composition which is a crosslinked reaction product of the rubber composition according to any one of claims 1 to 6, and has a Type A durometer hardness of 0 to 70 as measured under a temperature condition of 20 ± 5 ° C. in accordance with JIS K6253-3:2012.

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