Diene-grafted epoxy resin, method for producing diene-grafted epoxy resin, rubber composition and tire

Abstract

To provide an epoxy resin that exhibits increased durability when used together with a rubber material, and a production method for the epoxy resin.SOLUTION: A diene-grafted epoxy resin has a diene polymer grafted to the main chain of an epoxy resin. There are also provided a rubber composition containing the resin, and a tire including the composition.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a diene-grafted epoxy resin, a method for producing a diene-grafted epoxy resin, a rubber composition, and a tire. [Background technology]

[0002] In recent years, there has been a strong demand in the rubber industry to reduce the environmental impact, and technology that reduces the amount of rubber material used by improving durability has been attracting attention. As an example of such a technique, it is known that the durability of diene-based rubber materials can be improved by adding fillers such as carbon black and silica. However, further improvement in durability is required by investigating the molecular design of the filler and the filler-polymer interface.

[0003] In addition, as a resin material that contributes to durability, epoxy resin is known to have high strength and elastic modulus of its cured product, and excellent heat resistance and chemical resistance, and is used for various applications in the industrial field. On the other hand, the cured product of epoxy resin has low flexibility and has a problem with its fracture properties against strain. When the cured product of epoxy resin is used in automobiles or electrical parts, cracks may occur due to the application of vibration or force, and an improvement in this respect has been desired.

[0004] Therefore, as a technique for imparting flexibility to epoxy resins, Patent Documents 1 to 3 disclose terminal rubber modified epoxy resins in which butadiene rubber or acrylonitrile butadiene rubber is reacted with the terminals of epoxy resins. Furthermore, Patent Document 4 discloses a technique for improving the adhesiveness, toughness, and impact resistance of a cured product by containing an epoxy resin and polymer fine particles having a core-shell structure. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 58-49719 [Patent Document 2] Japanese Patent Application Publication No. 59-36124 [Patent Document 3] Japanese Patent Application Publication No. 61-228060 [Patent Document 4] JP 2016-199763 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, since a cured product of an epoxy resin has high polarity and low compatibility with rubber materials, sufficient durability cannot be achieved when the epoxy resin is contained in a rubber composition. In this regard, the epoxy resins modified with rubber terminals in Patent Documents 1 to 3 and the epoxy resin in Patent Document 4 have similar problems, and further improvements in terms of improving durability such as cut resistance, abrasion resistance, and fatigue resistance when used together with rubber materials are desired.

[0007] Therefore, an object of the present invention is to provide an epoxy resin that can enhance durability when used together with a rubber material, and a method for producing the epoxy resin. Another object of the present invention is to provide a rubber composition and a tire that are excellent in durability such as cut resistance, abrasion resistance, and fatigue resistance. [Means for solving the problem]

[0008] As a result of intensive research to solve the above problems, the present inventors have found that by grafting a specific diene polymer onto the main chain of an epoxy resin, the reactivity of the epoxy resin grafted with the diene polymer and a rubber material is increased, and the compatibility of the epoxy resin is improved, so that the durability (cut resistance, abrasion resistance, fatigue resistance, etc.) of the rubber material can be significantly improved. They also found that the epoxy resin grafted with a specific diene polymer can also have improved flexibility, adhesiveness, etc., compared to the epoxy resin alone, and have completed the present invention.

[0009] The present invention has been made based on these findings, and the gist of the present invention is as follows. The diene-grafted epoxy resin of the present invention is characterized in that a diene polymer is grafted onto the main chain of an epoxy resin. The above-mentioned structure enhances durability when used with a rubber material.

[0010] Furthermore, the diene-grafted epoxy resin of the present invention preferably has a number average molecular weight (Mn) of 5000 or more, because this allows for the realization of better durability.

[0011] Furthermore, in the diene-grafted epoxy resin of the present invention, the graft amount of the diene polymer is preferably 1 to 30 mol % relative to 100 mol % of the epoxy resin, because this allows for achieving better durability while increasing the strength and elastic modulus.

[0012] In addition, the diene-grafted epoxy resin of the present invention preferably further contains a boron atom, and more preferably is bonded to the main chain of the epoxy resin via the boron atom, because this can more reliably increase durability when used together with a rubber material.

[0013] Furthermore, the diene-grafted epoxy resin of the present invention preferably further contains a nitrogen atom, because this can more reliably improve durability when used together with a rubber material.

[0014] Furthermore, in the diene-grafted epoxy resin of the present invention, the diene-based polymer is preferably one or more rubbers selected from the group consisting of polybutadiene rubber, polyisoprene rubber, styrene butadiene rubber, acrylonitrile butadiene rubber, and polychloroprene rubber, because this allows for more excellent durability to be achieved.

[0015] The method for producing a diene-grafted epoxy resin of the present invention is characterized by reacting the present nitrogen-containing epoxy resin with a boronic acid-modified diene-based polymer. With the above-mentioned composition, the obtained diene-grafted epoxy resin can have improved durability when used together with a rubber material.

[0016] In the method for producing a diene-grafted epoxy resin of the present invention, the nitrogen-containing epoxy resin is preferably obtained by reacting bisphenol A diglycidyl ether with an amine compound, because the strength and elastic modulus of the diene-grafted epoxy resin can be increased.

[0017] The rubber composition of the present invention is characterized by containing a rubber component and the diene-grafted epoxy resin of the present invention. The above-mentioned configuration makes it possible to achieve excellent durability (cut resistance, abrasion resistance, fatigue resistance, etc.).

[0018] In the rubber composition of the present invention, the content of the diene-grafted epoxy resin is preferably 1 to 50 parts by mass based on 100 parts by mass of the rubber component, because this allows for achieving better durability without deteriorating other physical properties.

[0019] Furthermore, the rubber composition of the present invention preferably further contains silica, and the content of the silica is preferably 10 to 100 parts by mass per 100 parts by mass of the rubber component, because this allows for more excellent durability to be achieved without deteriorating other physical properties.

[0020] The tire of the present invention is characterized by using the rubber composition of the present invention. The above-mentioned configuration makes it possible to achieve excellent durability (cut resistance, abrasion resistance, fatigue resistance, etc.). Effect of the Invention

[0021] According to the present invention, it is possible to provide an epoxy resin capable of enhancing durability when used together with a rubber material, and a method for producing the epoxy resin. Moreover, according to the present invention, it is possible to provide a rubber composition and a tire that are excellent in durability such as cut resistance, abrasion resistance, and fatigue resistance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, the present invention will be described in detail based on embodiments thereof. (Diene grafted epoxy resin) The diene-grafted epoxy resin of the present invention is characterized in that a diene polymer is grafted onto the main chain of an epoxy resin.

[0023] By grafting a specific diene polymer onto epoxy resins, which are generally poorly compatible with rubber materials due to their large difference in polarity, the reactivity of the diene polymer-grafted epoxy resin with the rubber material is increased, improving the compatibility at the interface, and as a result, the durability of the rubber material (cut resistance, abrasion resistance, fatigue resistance, etc.) can be significantly improved. In addition, epoxy resins are known to enhance reinforcing properties through interaction with fillers such as silica, and it is possible to obtain a synergistic effect by using the diene-grafted epoxy resin of the present invention together with fillers such as silica. Furthermore, the inventors have found that the epoxy resin grafted with the diene polymer has improved flexibility, adhesiveness, etc., compared with the epoxy resin alone, and have thus completed the present invention.

[0024] Here, the diene-grafted epoxy resin of the present invention is not particularly limited except that a diene-based polymer is grafted, but from the viewpoint of obtaining better durability such as cut resistance, abrasion resistance, and fatigue resistance, the number average molecular weight (Mn) is preferably 5,000 or more, more preferably 20,000 or more, and even more preferably 50,000 or more.

[0025] (1) Epoxy resin The diene-grafted epoxy resin of the present invention has an epoxy resin backbone. By having an epoxy resin as the main chain, the strength (hardness) of the cured product can be increased. There are no limitations on the state, epoxy equivalent, molecular weight, molecular structure, etc. of the epoxy resin, and these can be appropriately selected depending on the required performance.

[0026] The type of the epoxy resin is not particularly limited and can be appropriately selected according to the required performance. Examples of the epoxy resin include bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD ​​type epoxy resin, stilbene type epoxy resin, biphenyl type epoxy resin, bisphenol A novolac type epoxy resin, cresol novolac type epoxy resin, diaminodiphenylmethane type epoxy resin, polyphenyl type epoxy resin such as tetrakis(hydroxyphenyl)ethane type epoxy resin, fluorene-containing epoxy resin, triglycidyl isocyanurate, triazine ring-containing epoxy resin, aromatic epoxy resin such as epoxy resin containing heteroaromatic ring, and non-aromatic epoxy resin such as aliphatic glycidyl ether type epoxy resin, aliphatic glycidyl ester type epoxy resin, alicyclic glycidyl ether type epoxy resin, alicyclic glycidyl ester type epoxy resin. These epoxy resins can be used alone or multiple types can be used simultaneously. Among these, the epoxy resin is preferably a bisphenol A type epoxy resin, and among the bisphenol A type epoxy resins, bisphenol A diglycidyl ether is more preferable.

[0027] The curing agent for the epoxy resin is not particularly limited and can be appropriately selected according to the required performance. Examples of the curing agent include aromatic curing agents such as metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, benzyldimethylamine, and dimethylaminomethylbenzene, phenol resins, phenol novolac resins, and amines having heteroaromatic rings such as triazine rings; ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, iminobispropylamine, bis(hexamethylene)triamine, 1,3,6-trisaminomethylhexane, polymethylenediamine, and trimethylhexamethylene. Examples of the non-aromatic curing agent include aliphatic amines such as diamine and polyether diamine, isophorone diamine, menthane diamine, N-aminoethyl piperazine, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5.5]undecane adduct, bis(4-amino-3-methylcyclohexyl)methane, 4,4'-methylenebis(cyclohexylamine) [also called "bis(4-aminocyclohexyl)methane"], or modified products thereof, and other aliphatic polyamidoamines consisting of polyamines and dimer acids. Note that these curing agents can be used alone or multiple types can be used simultaneously. Among these, the curing agent is preferably an amine compound (aromatic amine, amine having a heteroaromatic ring, aliphatic amines, alicyclic polyamines, aliphatic polyamidoamines), and more preferably an aliphatic amine.

[0028] The cured epoxy resin preferably contains nitrogen atoms, because this facilitates bonding with the diene polymer described below and enhances compatibility with rubber materials, thereby ensuring improved durability.

[0029] An example of the cured product of the nitrogen atom-containing epoxy resin is the following reaction. [ka]

[0030] (2) Diene polymers The diene-grafted epoxy resin of the present invention has a diene polymer grafted to the main chain of the epoxy resin. By having a diene polymer as a graft chain, the reactivity of the epoxy resin to which the diene polymer is grafted with the rubber material can be increased, improving the compatibility at the interface, which in turn makes it possible to greatly increase the durability (cut resistance, abrasion resistance, fatigue resistance, etc.) of the rubber material.

[0031] Here, the type of the diene polymer is not particularly limited, but from the viewpoint of improving compatibility with rubber materials, it is preferable that the diene polymer be one or more types of rubber selected from the group consisting of polybutadiene rubber, polyisoprene rubber, styrene butadiene rubber, ethylene-butadiene rubber, styrene-ethylene-butadiene rubber, acrylonitrile butadiene rubber, and polychloroprene rubber, and it is more preferable that the diene polymer be at least one type of rubber selected from the group consisting of polybutadiene rubber, polyisoprene rubber, and styrene butadiene rubber.

[0032] In addition, from the viewpoint of further improving durability such as cut resistance, abrasion resistance, and fatigue resistance without deteriorating other physical properties, the graft amount of the diene polymer is preferably 1 to 30 mol% relative to 100 mol% of the epoxy resin. By setting the graft amount of the diene polymer to 1 mol% or more relative to 100 mol% of the epoxy resin, the compatibility of the epoxy resin can be reliably improved and durability can be further improved, and further, by setting the graft amount of the diene polymer to 50 mol% or less relative to 100 mol% of the epoxy resin, the elastic modulus, strength, etc. of the epoxy resin can be well maintained. From the same viewpoint, the graft amount of the diene polymer is more preferably 3 to 40 mol%, and further preferably 5 to 30 mol%. The graft amount of the diene polymer can be confirmed by measuring the nuclear magnetic resonance spectrum, or, when the diene polymer to be grafted is completely consumed, by calculating from the charge ratio of the epoxy resin and the diene polymer.

[0033] The diene-grafted epoxy resin of the present invention may have a diene polymer grafted thereto, but it preferably further contains a boron atom and is preferably bonded to the main chain of the epoxy resin via the boron atom, because this improves the efficiency of the reaction during graft polymerization and can more reliably increase the durability when used together with a rubber material.

[0034] As a method for incorporating the boron atom into the diene-grafted epoxy resin, for example, a boronic acid-modified diene-based polymer is used as the diene-based polymer for grafting, and the main chain of the epoxy resin and the diene-based polymer are bonded via the boron atom (i.e., the boron atom can be incorporated into the diene-grafted epoxy resin) as described later. Examples of the boronic acid modified diene polymer include boronic acid modified butadiene rubber, boronic acid modified isoprene rubber, and boronic acid modified styrene-butadiene rubber.

[0035] (3) Manufacturing method of diene grafted epoxy resin The method for producing the diene-grafted epoxy resin of the present invention is not particularly limited as long as it is a method capable of grafting the diene polymer onto the main chain of the epoxy resin. For example, as shown below, a boronic acid-modified diene polymer (in the following formula: (BR-B(OEt))) is grafted onto a nitrogen atom-containing epoxy resin. 2 or BR-B(OH) 2 ), and BR means butadiene rubber as an example of a diene polymer) to obtain a diene-grafted epoxy resin (butadiene-grafted epoxy resin). [ka]

[0036] The reaction between the nitrogen-containing epoxy resin and the boronic acid-modified diene polymer can be carried out, for example, by mixing them in a solvent such as chloroform and then evaporating the solvent. The epoxy resin contains nitrogen atoms and the diene polymer is modified with boronic acid, so that the reaction sites of both react with each other, making it possible to easily produce the polymer.

[0037] (Rubber composition) The rubber composition of the present invention is characterized by containing a rubber component and the above-mentioned diene-grafted epoxy resin of the present invention. By having the above-mentioned configuration, the reactivity between the diene-grafted epoxy resin of the present invention and the rubber component is increased, and the compatibility of the epoxy resin is improved, so that the durability (cut resistance, abrasion resistance, fatigue resistance, etc.) of the rubber composition can be improved.

[0038] Here, the content of the diene grafted epoxy resin in the rubber composition of the rubber composition of the present invention is preferably 1 to 50 parts by mass per 100 parts by mass of the rubber component. If the content of the diene grafted epoxy resin is 1 part by mass per 100 parts by mass of the rubber component, sufficient durability of the rubber composition can be ensured, and if the content of the diene grafted epoxy resin is 50 parts by mass or less per 100 parts by mass of the rubber component, deterioration of other physical properties such as crack growth resistance and heat generation can be suppressed. From the same viewpoint, the content of the diene grafted epoxy resin is more preferably 5 to 40 parts by mass, and further preferably 10 to 30 parts by mass per 100 parts by mass of the rubber component.

[0039] The components of the rubber composition of the present invention other than the graft copolymer are not particularly limited, and any desired components may be contained according to requirements.

[0040] The rubber component can be appropriately selected according to the required performance. For example, diene rubbers such as natural rubber (NR), butadiene rubber (BR), isoprene rubber (IR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), ethylene-butadiene rubber, and styrene-ethylene-butadiene rubber, and non-diene rubbers such as ethylene propylene diene rubber (EPDM), ethylene propylene rubber (EPM), and butyl rubber (IIR) can be mentioned. Among these, it is preferable to include one or more of the diene rubbers from the viewpoint of high compatibility with the diene grafted epoxy resin and further improving durability.

[0041] From the viewpoint of further improving durability such as cut resistance, abrasion resistance, and fatigue resistance, the rubber composition of the present invention preferably further contains a reinforcing filler. The reinforcing filler may be any reinforcing filler commonly used in the rubber field, such as silica, carbon black, talc, clay, aluminum hydroxide, titanium oxide, etc. Among these, it is preferable to contain at least silica, from the viewpoint of further enhancing durability by a synergistic effect with the diene-grafted epoxy resin of the rubber composition.

[0042] The type of silica is not particularly limited, and examples thereof include wet silica, colloidal silica, calcium silicate, and aluminum silicate. Among the above, the silica is preferably wet silica, and more preferably precipitated silica, because these silicas have high dispersibility and can further improve the low loss and abrasion resistance of the rubber composition. Note that precipitated silica is silica obtained by growing silica primary particles by proceeding with the reaction in a reaction solution at a relatively high temperature and in a neutral to alkaline pH range in the early stages of production, and then controlling the reaction solution to the acidic side to aggregate the primary particles.

[0043] The silica is not particularly limited, but may be, for example, a silica having a CTAB specific surface area (cetyltrimethylammonium bromide adsorption specific surface area) of 70 m 2 / g or more, 250m 2 The CTAB specific surface area is a value measured in accordance with ASTM D3765-92. However, the adsorption cross section of one molecule of cetyltrimethylammonium bromide on the silica surface is set to 0.35 nm 2 The specific surface area (m2) calculated from the amount of CTAB adsorbed is 2 / g) is the specific surface area of ​​CTAB. The BET specific surface area of ​​the silica is 100 m 2 / g or more, 250m 2 The BET specific surface area is a specific surface area determined by a BET method, and in the present invention, can be measured in accordance with ASTM D4820-93.

[0044] The content of the silica is not particularly limited, but is preferably 10 to 160 parts by mass, more preferably 20 to 120 parts by mass, and particularly preferably 30 to 100 parts by mass, per 100 parts by mass of the rubber component. By setting the content of the silica to 30 parts by mass or more per 100 parts by mass of the rubber component, a synergistic effect with the diene-grafted epoxy resin can be achieved, making it possible to obtain better durability. By setting the content of the silica to 100 parts by mass or less, deterioration of physical properties such as processability can be more reliably suppressed.

[0045] The type of carbon black is not particularly limited. For example, any hard carbon or soft carbon produced by an oil furnace method can be used. The carbon black is not particularly limited, and examples thereof include GPF, FEF, HAF, ISAF, and SAF grade carbon black. 2 SA, measured in accordance with JIS K 6217-2:2001) is 20 to 250 m2 / g of carbon black can be used. Among these, ISAF and SAF grade carbon black are preferred from the viewpoint of improving the abrasion resistance of the rubber composition. These carbon blacks may be used alone or in combination of two or more.

[0046] The content of the carbon black is not particularly limited. For example, it is preferably 0 to 70 parts by mass, more preferably 10 to 60 parts by mass, and particularly preferably 20 to 50 parts by mass, relative to 100 parts by mass of the rubber component. By making the content of the carbon black 20 parts by mass or more relative to 100 parts by mass of the rubber component, more excellent durability can be obtained, and by making the content 50 parts by mass or less, deterioration of low heat build-up can be more reliably prevented. Furthermore, the content ratio (mass ratio) of the carbon black to the silica is not particularly limited. For example, the carbon black:silica content ratio is preferably 1:15 to 3:1, more preferably 1:12 to 1:1, and particularly preferably 1:10 to 1:2. By setting the carbon black:silica content ratio in the range of 1:15 to 3:1, fatigue resistance and tear resistance can be further improved.

[0047] The rubber composition of the present invention may contain additives (other components) that are usually compounded in rubber compositions to the extent that the effects of the invention are not impaired. For example, additives that are usually used in the rubber industry, such as silane coupling agents, antiaging agents, crosslinking accelerators, crosslinking agents, crosslinking accelerator assistants, softeners, stearic acid, antiozonants, and surfactants, may be appropriately contained.

[0048] When the rubber composition of the present invention contains the silica, it is preferable that the rubber composition further contains a silane coupling agent, because this can enhance the dispersibility of the silica and provide better durability. Examples of the silane coupling agent include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl Examples of the silane coupling agent include -N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropyl benzothiazolyl tetrasulfide, 3-triethoxysilylpropyl benzothiazolyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis(3-diethoxymethylsilylpropyl)tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, dimethoxymethylsilylpropyl benzothiazolyl tetrasulfide, etc. These silane coupling agents may be used alone or in combination of two or more.

[0049] The antiaging agent may be any known agent and is not particularly limited. For example, phenol-based antiaging agents, imidazole-based antiaging agents, amine-based antiaging agents, etc. may be used. These antiaging agents may be used alone or in combination of two or more.

[0050] The crosslinking accelerator may be a known one and is not particularly limited. For example, thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole and dibenzothiazyl disulfide, sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazyl sulfenamide and Nt-butyl-2-benzothiazyl sulfenamide, guanidine-based vulcanization accelerators such as diphenyl guanidine, thiuram-based vulcanization accelerators such as tetramethyl thiuram disulfide, tetraethyl thiuram disulfide, tetrabutyl thiuram disulfide, tetradodecyl thiuram disulfide, tetraoctyl thiuram disulfide, tetrabenzyl thiuram disulfide, and dipentamethylene thiuram tetrasulfide, dithiocarbamate-based vulcanization accelerators such as zinc dimethyldithiocarbamate, and zinc dialkyldithiophosphate can be mentioned.

[0051] The crosslinking agent is not particularly limited, and examples thereof include sulfur, bismaleimide compounds, and peroxides. Examples of the bismaleimide compound include N,N'-o-phenylene bismaleimide, N,N'-m-phenylene bismaleimide, N,N'-p-phenylene bismaleimide, N,N'-(4,4'-diphenylmethane)bismaleimide, 2,2-bis-[4-(4-maleimidophenoxy)phenyl]propane, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane, etc. In the present invention, N,N'-m-phenylene bismaleimide and N,N'-(4,4'-diphenylmethane)bismaleimide, etc. can be suitably used.

[0052] Examples of the crosslinking promoter include zinc oxide (ZnO) and fatty acids. The fatty acid may be any of saturated or unsaturated, linear or branched fatty acids, and the number of carbon atoms of the fatty acid is not particularly limited. Examples of the fatty acid include fatty acids having 1 to 30 carbon atoms, preferably 15 to 30 carbon atoms, more specifically naphthenic acids such as cyclohexanoic acid (cyclohexane carboxylic acid) and alkylcyclopentane having a side chain; saturated fatty acids such as hexanoic acid, octanoic acid, decanoic acid (including branched carboxylic acids such as neodecanoic acid), dodecanoic acid, tetradecanoic acid, hexadecanoic acid, and octadecanoic acid (stearic acid); unsaturated fatty acids such as methacrylic acid, oleic acid, linoleic acid, and linolenic acid; and resin acids such as rosin, tall oil acid, and abietic acid. These may be used alone or in combination of two or more. In the present invention, zinc oxide and stearic acid can be preferably used.

[0053] <Tires> The tire of the present invention is characterized by using the above-mentioned rubber composition of the present invention. By including the rubber composition of the present invention as a tire material, excellent durability (cut resistance, abrasion resistance, fatigue resistance, etc.) can be realized. In the tire of the present invention, the portion to which the rubber composition of the present invention is applied is not particularly limited, but it is preferably used in the tread portion. A tire using the rubber composition of the present invention in the tread portion has excellent durability.

[0054] The tire of the present invention can be manufactured according to a conventional method without any particular limitation other than using the above-mentioned rubber composition of the present invention for any of the tire components. The gas to be filled in the tire can be normal air or air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium.

[0055] (Other items) The above-mentioned rubber composition of the present invention can also be applied to rubber articles other than tires (hereinafter referred to as "other rubber articles"). The other rubber articles are not particularly limited, but examples thereof include vibration-proof rubber, seismic isolation rubber, crawlers, belts, hoses, and the like. EXAMPLES

[0056] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these.

[0057] (Preparation of diene-grafted epoxy resin) Epoxy resins and diene-grafted epoxy resins 1 to 4 were prepared under the following conditions.

[0058] (1) Epoxy resin Bisphenol A diglycidyl ether and a mixture of propylamine and polyetheramine (D2000) as an amine compound in a molar ratio of 1:2 were reacted at 100°C for 30 minutes to obtain epoxy resin 1, referring to Chemical Communications 2018, 54, 12930-12933.

[0059] (2) Diene-grafted epoxy resin 1-4 Boronic acid modified butadiene (BR-B(OH) 2 ) was synthesized by anionic polymerization using BR-Li, and BR1 (molecular weight 5000) and BR2 (molecular weight 30000) with different molecular weights of the polybutadiene part were synthesized with reference to Organometallics 1983, 2, 1316. Diene graft epoxy resins 1 to 4 were obtained by mixing the above epoxy resin 1 or 2 and boronic acid modified butadiene in chloroform in the following ratios, and then evaporating the chloroform. Diene graft epoxy resin 1-Epoxy resin 1: 10g, BR1: 1.8g Diene graft epoxy resin 2-Epoxy resin 2: 10g, BR2: 11g Diene graft epoxy resin 3-Epoxy resin 2: 10g, BR1: 1.5g Diene graft epoxy resin 4-Epoxy resin 2: 10g, BR2: 8.9g The amount of polybutadiene grafted in each diene-grafted epoxy resin was calculated based on the assumption that the epoxy resin and polybutadiene were completely reacted, and the amount of polybutadiene grafted in 100 mol% epoxy was calculated. The calculated values ​​will be described later.

[0060] <Examples 1 to 4, Comparative Examples 1 to 2> According to the compounding recipe shown in Table 1, rubber composition samples were prepared using a conventional Banbury mixer and subjected to the following evaluations.

[0061] <Evaluation> (1) Fatigue resistance Each sample rubber composition was vulcanized at 160°C for 15 minutes to obtain vulcanized rubber. Dumbbell-shaped test pieces were then prepared in accordance with JIS K 6270:2001, and tests were performed at a test strain of 100%, a test frequency of 5 Hz, and a test temperature of 40°C to measure the number of repetitions until breakage. The evaluation was expressed as an index value, with the number of times until the sample of Comparative Example 1 broke being taken as 100, and the results are shown in Table 1. Note that a larger index value indicates a larger number of times until breakage and better fatigue resistance.

[0062] (2) Tear resistance Each sample rubber composition was vulcanized at 160° C. for 15 minutes to give a vulcanized rubber, and then the tear strength (MPa) was measured in a trouser form according to JIS K6252 using a tensile testing device (Shimadzu Corporation). The evaluation was expressed as an index value when the tear strength of the sample of Comparative Example 1 was set to 100, and the results are shown in Table 1. The larger the index value, the better the tear resistance and the more excellent the durability.

[0063] [Table 1]

[0064] *1 Styrene butadiene rubber: T2000 *2 Diene-grafted epoxy resin 1: Polybutadiene graft amount 5 mol% per 100 mol% epoxy resin *3 Diene-grafted epoxy resin 2: Polybutadiene graft amount is 5 mol% per 100 mol% epoxy resin. *4 Diene-grafted epoxy resin 3: Polybutadiene graft amount 5 mol% per 100 mol% epoxy resin *5 Diene-grafted epoxy resin 4: Polybutadiene graft amount is 5 mol% per 100 mol% epoxy resin. *6 Carbon black: SAF grade carbon black, manufactured by Asahi Carbon Co., Ltd., product name "ASAHI#105" *7 Silica: Tosoh Silica Corporation, "NIPSIL AQ" *8 Silane coupling agent: "ABC-856" manufactured by Shin-Etsu Chemical Co., Ltd. *9 Wax: Microcrystalline wax, manufactured by Seiko Chemical Co., Ltd. *10 Anti-aging agent: Ouchi Shinko Chemical Industry Co., Ltd., product name "Nocrac 6C" *11 Vulcanization accelerator DPG: Manufactured by Ouchi Shinko Chemical Industry Co., Ltd., product name "Noccelaer D" *12 Vulcanization accelerator MBTS: Di-2-benzothiazolyl disulfide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., product name "Noccela DM-P" *13 Vulcanization accelerator NS: N-tert-butyl-2-benzothiazolylsulfenamide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., product name "Noccela NS-P (NS)" *14 Zinc oxide: manufactured by Hakusui Tech

[0065] From Table 1, it can be seen that the samples of the examples containing diene-grafted epoxy resins 1 to 4 of the present invention exhibited superior results in both fatigue resistance and tear resistance compared to the sample of Comparative Example 1, and were therefore superior in durability. [Industrial Applicability]

[0066] According to the present invention, it is possible to provide an epoxy resin capable of enhancing durability when used together with a rubber material, and a method for producing the epoxy resin. Moreover, according to the present invention, it is possible to provide a rubber composition and a tire that are excellent in durability such as cut resistance, abrasion resistance, and fatigue resistance.

Claims

1. A diene-grafted epoxy resin in which a diene polymer is grafted onto the main chain of an epoxy resin, the graft amount of the diene polymer is 1 to 30 mol % relative to 100 mol % of the epoxy resin, A diene-grafted epoxy resin further comprising a boron atom, wherein the diene polymer is bonded to a main chain of the epoxy resin via the boron atom.

2. 2. The diene-grafted epoxy resin according to claim 1, further comprising a nitrogen atom.

3. The diene-grafted epoxy resin according to claim 1 or 2, characterized in that the diene-based polymer is one or more rubbers selected from the group consisting of polybutadiene rubber, polyisoprene rubber, styrene butadiene rubber, ethylene-butadiene rubber, styrene-ethylene-butadiene rubber, acrylonitrile butadiene rubber, and polychloroprene rubber.

4. The method includes a step of reacting a nitrogen atom-containing epoxy resin with a boronic acid-modified diene polymer, A method for producing a diene-grafted epoxy resin, characterized in that the graft amount of the boronic acid-modified diene polymer is 1 to 30 mol % based on 100 mol % of the nitrogen atom epoxy resin.

5. 5. The method for producing a diene-grafted epoxy resin according to claim 4, wherein the nitrogen-containing epoxy resin is obtained by reacting bisphenol A diglycidyl ether with an amine compound.

6. A rubber composition comprising a rubber component and the diene-grafted epoxy resin according to any one of claims 1 to 3.

7. The rubber composition according to claim 6, wherein the content of the diene-grafted epoxy resin is 1 to 50 parts by mass based on 100 parts by mass of the rubber component.

8. The rubber composition according to claim 7, further comprising silica, the content of the silica being 10 to 100 parts by mass per 100 parts by mass of the rubber component.

9. A tire comprising the rubber composition according to any one of claims 6 to 8.