Diene polymer rubber

Abstract

The present invention provides a conjugated diene rubber containing a diene monomer unit and a (meth) acrylic acid ester monomer unit, the content ratio of the (meth) acrylic acid ester monomer unit being 1-40 wt%.

Description

Technical Field

[0001] The present invention relates to a diene polymer rubber, and more particularly to a diene polymer rubber capable of forming a rubber cross-linked product having excellent friction properties on ice and high affinity for water. Background Art

[0002] Diene polymer rubber can be produced by an emulsion polymerization method in which polymerization is carried out in an aqueous medium in the presence of an emulsifier, a solution polymerization method in which polymerization is carried out in an organic solvent using an anionic polymerization catalyst, etc., and can be used for various purposes. For example, diene polymer rubber is preferably used for various purposes such as rubber materials for tires and rubber materials for shoe soles.

[0003] For example, Patent Document 1 discloses a rubber composition that can be used for tires and has improved friction on ice, characterized in that it is formed by adding 20 to 70 parts by mass of at least one filler selected from carbon black and white fillers, and 1 to 30 parts by mass of a spherical and non-hollow (meth) alkyl acrylate polymer having a particle size of 0.1 μm to 100 μm to 100 μm, relative to 100 parts by mass of diene rubber. However, in the technology of Patent Document 1, the effect of improving friction on ice is limited, and it is required to further improve friction on ice (frictional properties on ice).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2012-158710. Summary of the invention

[0007] Problem that the invention aims to solve

[0008] The present invention has been made in view of such actual circumstances, and an object of the present invention is to provide a diene polymer rubber which exhibits high affinity for water and can form a rubber cross-linked product having excellent friction properties on ice, for example.

[0009] Solutions for solving problems

[0010] The present inventors have conducted studies to achieve the above object and have found that the above problems can be solved by a diene polymer rubber containing (meth)acrylic acid ester monomer units at a specific content ratio, thereby completing the present invention.

[0011] That is, according to the present invention, there are provided the following diene polymer rubber and method for producing the diene polymer rubber.

[0012] [1] A diene polymer rubber, which is a conjugated diene polymer rubber containing a diene monomer unit and a (meth)acrylic acid ester monomer unit,

[0013] The content ratio of the (meth)acrylic acid ester monomer unit is 1 to 40% by weight.

[0014] [2] The diene polymer rubber according to [1], wherein the diene polymer rubber has a glass transition temperature of -100 to -50°C.

[0015] [3] The diene polymer rubber according to [1] or [2], wherein the (meth)acrylic acid ester monomer unit is an alkoxyalkyl (meth)acrylate monomer unit.

[0016] [4] The diene polymer rubber according to any one of [1] to [3], wherein the diene polymer rubber has a slide angle of 38° or more.

[0017] [5] A method for producing a diene polymer rubber, which is a method for producing the diene polymer rubber described in any one of [1] to [4], comprising the following steps: a step of polymerizing a monomer mixture containing a diene monomer and a (meth)acrylate monomer in an aqueous medium in the presence of an emulsifier.

[0018] Effects of the Invention

[0019] According to the present invention, there can be provided a diene polymer rubber capable of forming a rubber cross-linked product having excellent friction properties on ice and high affinity for water. DETAILED DESCRIPTION

[0020] The diene polymer rubber of the present invention contains a diene monomer unit and a (meth)acrylic acid ester monomer unit, and the content ratio of the (meth)acrylic acid ester monomer unit is 1 to 40% by weight.

[0021] The diene monomers forming the diene monomer units are not particularly limited, and examples thereof include conjugated diene monomers such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, 2-phenyl-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene; and non-conjugated diene monomers such as 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, dicyclopentadiene, and 5-ethylidene-2-norbornene. Among these, conjugated diene monomers are preferred, 1,3-butadiene and isoprene are more preferred, and 1,3-butadiene is further preferred. These diene monomers may be used alone or in combination of two or more.

[0022] The content of the diene monomer units in the diene polymer rubber of the present invention is preferably 60 to 99% by weight, more preferably 70 to 97% by weight, further preferably 75 to 95% by weight, and particularly preferably 80 to 93% by weight. When the content of the diene monomer units is 60% by weight or more, the rubber elasticity of the obtained cross-linked rubber can be sufficient, and when the content of the diene monomer units is 99% by weight or less, the friction on ice and the affinity for water of the obtained cross-linked rubber can be further improved.

[0023] The vinyl bond content in the diene monomer unit in the diene polymer rubber of the present invention is preferably 5 to 30 mol%, more preferably 8 to 20 mol%, further preferably 10 to 20 mol%, and particularly preferably 13 to 18 mol%. By making the vinyl bond content in the diene monomer unit below the above upper limit, the reduction in ice performance due to the increase in hardness of the rubber can be appropriately suppressed. On the other hand, by making the vinyl bond content in the diene monomer unit above the above lower limit, the strength of the polymer can be further improved.

[0024] The (meth)acrylate monomers forming the (meth)acrylate monomers [referring to acrylate monomers and / or methacrylate monomers. Hereinafter, the same as methyl (meth)acrylate] units are not particularly limited, and examples thereof include alkyl (meth)acrylate monomers and alkoxyalkyl (meth)acrylate monomers. From the viewpoint of high affinity with water, alkoxyalkyl (meth)acrylate monomers are preferred.

[0025] The (meth)acrylic acid alkyl ester monomer is not particularly limited, but is preferably an ester of an alkanol having 1 to 12 carbon atoms and (meth)acrylic acid (i.e., a (meth)acrylic acid ester having an alkyl group having 1 to 12 carbon atoms), more preferably an ester of an alkanol having 1 to 8 carbon atoms and (meth)acrylic acid (i.e., a (meth)acrylic acid ester having an alkyl group having 1 to 8 carbon atoms), and still more preferably an ester of an alkanol having 2 to 6 carbon atoms and (meth)acrylic acid (i.e., a (meth)acrylic acid ester having an alkyl group having 2 to 6 carbon atoms).

[0026] Specific examples of the (meth)acrylic acid alkyl ester monomer include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and cyclohexyl (meth)acrylate. Among these, ethyl (meth)acrylate and n-butyl (meth)acrylate are preferred, ethyl acrylate and n-butyl acrylate are more preferred, and n-butyl acrylate is further preferred. These can be used alone or in combination of two or more.

[0027] The alkoxyalkyl (meth)acrylate monomer is not particularly limited, but esters of an alkoxyalkyl alcohol having 2 to 12 carbon atoms and (meth)acrylic acid (i.e., (meth)acrylic acid esters having an alkoxyalkyl group having 2 to 12 carbon atoms) are preferred, esters of an alkoxyalkyl alcohol having 2 to 8 carbon atoms and (meth)acrylic acid (i.e., (meth)acrylic acid esters having an alkoxyalkyl group having 2 to 8 carbon atoms) are more preferred, and esters of an alkoxyalkyl alcohol having 2 to 6 carbon atoms and (meth)acrylic acid (i.e., (meth)acrylic acid esters having an alkoxyalkyl group having 2 to 6 carbon atoms) are particularly preferred.

[0028] As specific examples of (meth) alkoxyalkyl acrylate monomers, methoxymethyl (meth) acrylate, ethoxymethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-propoxyethyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, and 4-methoxybutyl (meth) acrylate, etc., can be cited. Among these, 2-ethoxyethyl (meth) acrylate and 2-methoxyethyl (meth) acrylate are preferred, 2-ethoxyethyl acrylate and 2-methoxyethyl acrylate are more preferred, and 2-methoxyethyl acrylate is particularly preferred. These can be used alone or in combination of two or more.

[0029] The content of the (meth)acrylate monomer units in the diene polymer rubber of the present invention is 1 to 40% by weight, preferably 3 to 30% by weight, more preferably 5 to 25% by weight, and further preferably 7 to 20% by weight. When the content of the (meth)acrylate monomer units is too low, the affinity for water and the friction on ice of the obtained rubber cross-linked product deteriorate, while when the content is too high, the rubber cross-linked product deteriorates in the expression of rubber elasticity.

[0030] In addition, the diene polymer rubber of the present invention may contain an aromatic vinyl monomer unit in addition to the conjugated diene monomer unit and the (meth)acrylate monomer unit. As the aromatic vinyl monomer used to form the aromatic vinyl monomer unit, for example, styrene, methyl styrene, ethyl styrene, tert-butyl styrene, α-methyl styrene, α-methyl p-methyl styrene, chlorostyrene, bromostyrene, methoxystyrene, dimethylaminomethyl styrene, dimethylaminoethyl styrene, diethylaminomethyl styrene, diethylaminoethyl styrene, cyanoethyl styrene, vinyl naphthalene, etc. can be cited. Among these, styrene is preferred.

[0031] The content of the aromatic vinyl monomer units in the diene polymer rubber of the present invention is preferably 1 to 25% by weight, more preferably 3 to 20% by weight, and even more preferably 5 to 15% by weight.

[0032] In addition, the diene polymer rubber of the present invention may contain other monomer units in addition to the conjugated diene monomer units, (meth)acrylate monomer units, and aromatic vinyl monomer units as required. Examples of other compounds constituting such other monomer units include: chain olefin compounds such as ethylene, propylene, and 1-butene; cyclic olefin compounds such as cyclopentene and 2-norbornene; α,β-ethylenically unsaturated monocarboxylic acids such as (meth)acrylic acid, ethacrylic acid, crotonic acid, and cinnamic acid; α,β-ethylenically unsaturated polycarboxylic acids such as fumaric acid and maleic acid; butenedioic acid such as itaconic acid, citraconic acid, mesaconic acid, glutaconic acid, allylmalonic acid, and rutaconic acid; maleic anhydride, itaconic acid Anhydrides of α,β-unsaturated polycarboxylic acids such as monomethyl maleate, monoethyl maleate, monopropyl maleate, mono-n-butyl maleate, monocyclopentyl maleate, monocyclohexyl maleate, monocycloheptyl maleate, monomethyl fumarate, monoethyl fumarate, monopropyl fumarate, mono-n-butyl fumarate, monoalkyl fumarates such as monomethyl fumarate, monoethyl fumarate, monopropyl fumarate, mono-n-butyl fumarate, and monocycloalkyl fumarates such as monocyclopentyl fumarate, monocyclohexyl fumarate, and monocycloheptyl fumarate.

[0033] The bonding form of each monomer unit in the diene polymer rubber of the present invention can be various bonding forms such as block, tapered, and random, and a random bonding form is preferred. By making the bonding form random, the friction on ice and affinity for water of the obtained rubber cross-linked product can be further improved.

[0034] The glass transition temperature (Tg) of the diene polymer rubber of the present invention is preferably -100 to -50°C, more preferably -95 to -60°C, further preferably -90 to -70°C, and particularly preferably -80 to -70°C. When the glass transition temperature is too low, the processability deteriorates. On the other hand, when the glass transition temperature is too high, the friction on ice of the obtained rubber cross-linked product deteriorates. In addition, the glass transition temperature of the diene polymer rubber can be controlled by, for example, the following methods: a method of selecting the type of (meth)acrylate monomer used; a method of adjusting the content ratio of the (meth)acrylate monomer unit; and a method of adjusting the amount of vinyl bonds; a method of adjusting the type and amount of other monomer units such as aromatic vinyl monomer units.

[0035] The Mooney viscosity (ML1+4) of the diene polymer rubber of the present invention is preferably 10 to 200, more preferably 20 to 150, and particularly preferably 30 to 80. When the Mooney viscosity is within the above range, processability becomes better. The Mooney viscosity (ML1+4) can be measured at 100° C. in accordance with JIS K6300-1:2013.

[0036] The method for producing the diene polymer rubber of the present invention is not particularly limited, and can be produced by copolymerizing a diene monomer and a (meth) acrylate monomer. The polymerization method is not particularly limited, and can be based on a known emulsion polymerization method or a solution polymerization method. From the viewpoint of industrial productivity, an emulsion polymerization method is preferred. That is, it is a method in which a monomer mixture containing a diene monomer and a (meth) acrylate monomer is polymerized in an aqueous medium, preferably in the presence of an emulsifier. When performing emulsion polymerization, in addition to using an emulsifier, a polymerization initiator and a molecular weight modifier can also be used. In addition, in addition to these, commonly used polymerization auxiliary materials can also be used.

[0037] As emulsifier, there is no particular limitation, and carboxylic acid emulsifier can be preferably used. As carboxylic acid emulsifier, fatty acid soap or rosin acid soap can be exemplified. As fatty acid soap, long-chain aliphatic carboxylic acid with 12 to 18 carbon atoms, such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, and sodium salts or potassium salts of mixed aliphatic carboxylic acids thereof can be used. In addition, as rosin acid soap, sodium salts or potassium salts of products obtained by disproportionation or hydrogenation of natural rosins such as gum rosin, wood rosin or tall oil rosin can be cited. As natural rosin, natural rosin with abietic acid, levopimaric acid, palustric acid, dehydroabietic acid, tetrahydroabietic acid and neoabietic acid as main components can be cited. The amount of emulsifier used is preferably 0.05 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, relative to 100 parts by weight of the monomer used in the polymerization.

[0038] As a polymerization initiator, as long as it is a free radical initiator, it is not particularly limited, and can be cited: inorganic peroxides such as potassium persulfate, sodium persulfate, ammonium persulfate, potassium perphosphate, and hydrogen peroxide; organic peroxides such as tert-butyl peroxide, cumene hydroperoxide, tert-butyl peroxide isopropylbenzene, acetyl peroxide, isobutyl peroxide, octanoyl peroxide, dibenzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, tert-butyl peroxyisobutyrate, and diisopropylbenzene hydroperoxide; azo compounds such as azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, and methyl azobisisobutyrate. These polymerization initiators can be used alone or in combination of two or more. As a polymerization initiator, inorganic or organic peroxides are preferred. When a peroxide is used as a polymerization initiator, it can be combined with a reducing agent and used as a redox polymerization initiator. The reducing agent is not particularly limited, and examples thereof include compounds containing metal ions in a reduced state, such as ferrous sulfate and cuprous naphthenate; sulfinates such as sodium hydroxymethanesulfinate; sulfites such as sodium sulfite, potassium sulfite, sodium hydrogen sulfite, sodium aldehyde hydrogen sulfite, potassium hydrogen sulfite, etc. The amount of the polymerization initiator added is preferably 0.01 to 2 parts by weight relative to 100 parts by weight of the monomers used in the polymerization.

[0039] The molecular weight modifier is not particularly limited, and examples thereof include: α-methylstyrene dimer; thiols such as tert-dodecyl mercaptan, n-dodecyl mercaptan, and octyl mercaptan; halogenated hydrocarbons such as carbon tetrachloride, dichloromethane, and dibromomethane; sulfur-containing compounds such as tetraethylthiuram disulfide, dipentamethylenethiuram disulfide, and diisopropylxanthate disulfide, etc. Among these, thiols are preferred, and tert-dodecyl mercaptan is more preferred. These molecular weight modifiers may be used alone or in combination of two or more. The amount of the molecular weight modifier used varies depending on the type, and is preferably 0.1 to 1.5 parts by weight, and more preferably 0.2 to 1.0 parts by weight, relative to 100 parts by weight of the monomer used in the polymerization.

[0040] An aqueous medium such as water is generally used as a medium for emulsion polymerization. The amount of the aqueous medium is preferably 80 to 500 parts by weight, more preferably 80 to 300 parts by weight, based on 100 parts by weight of the monomers used in the polymerization.

[0041] When emulsion polymerization is performed, polymerization auxiliary materials such as stabilizers, dispersants, pH adjusters, deoxidizers, and particle size adjusters may be used as needed. When these materials are used, their types and amounts are not particularly limited.

[0042] As a method for adding monomers, for example, a method of adding the monomers used in a reaction vessel at one time, a method of adding continuously or intermittently as the polymerization proceeds, a method of adding a portion of the monomers to react to a specific conversion rate, and then continuously or intermittently adding the remaining monomers and polymerizing, etc., can be cited, and any method can be adopted. In the case of mixing the monomers and adding continuously or intermittently, the composition of the mixture can be fixed or can also be changed. In addition, each monomer can be added to the reaction vessel after the various monomers used are mixed in advance, or can also be added to the reaction vessel separately.

[0043] The polymerization temperature during emulsion polymerization is not particularly limited, but is usually 0 to 95° C., preferably 5 to 70° C. The polymerization time is not particularly limited, but is usually about 5 to 40 hours.

[0044] The polymerization terminator is not particularly limited as long as it is a polymerization terminator generally used in emulsion polymerization, and specific examples thereof include: hydroxylamine compounds such as hydroxylamine, hydroxylamine sulfate, diethylhydroxylamine, hydroxylamine sulfonic acid and its alkali metal salts; sodium dimethyldithiocarbamate; hydroquinone derivatives; catechol derivatives; aromatic hydroxydithiocarboxylic acids such as hydroxydimethylbenzenethiocarboxylic acid, hydroxydiethylbenzenethiocarboxylic acid, hydroxydibutylbenzenethiocarboxylic acid and their alkali metal salts and aromatic hydroxydithiocarboxylic acid compounds, etc. The amount of the polymerization terminator used is not particularly limited, and is generally 0.05 to 2 parts by weight relative to 100 parts by weight of the monomers used in the polymerization.

[0045] Furthermore, the latex of the copolymer obtained by emulsion polymerization can be coagulated by salting out or alcohol, filtered, dried, etc. after adding an antioxidant such as a phenol stabilizer, a phosphorus stabilizer, a sulfur stabilizer, etc. as desired, thereby obtaining the diene polymer rubber of the present invention. The filtering and drying steps after coagulation in this case can be carried out by known methods, respectively. The amount of the antioxidant added is preferably 0.05 to 2 parts by weight relative to 100 parts by weight of the diene polymer rubber or 100 parts by weight of the monomer used in the polymerization.

[0046] The slide angle (dynamic contact angle) of the diene polymer rubber of the present invention is preferably 38° or more, more preferably 40° or more, further preferably 42° or more, and particularly preferably 44° or more. In addition, the upper limit of the slide angle is not particularly limited, and is usually 65° or less. Regarding the slide angle, 2 μL of water droplets can be dripped on the diene polymer rubber formed into a specified shape, the diene polymer rubber is gradually tilted at a uniform speed, and the angle at which the water droplets begin to slide is measured, and the angle at which the water droplets begin to slide is used as the slide angle (dynamic contact angle). The larger the slide angle, the better the wettability of water is, and the higher the affinity for water is. In addition, in the present invention, it is also preferred that the slide angle (dynamic contact angle) of the rubber composition and the rubber cross-linked product obtained using the diene polymer rubber of the present invention is within the above range. That is, the rubber composition or rubber cross-linked product obtained using the diene polymer rubber of the present invention preferably has a slide angle (dynamic contact angle) of 38° or more, more preferably 40° or more, further preferably 42° or more, and particularly preferably 44° or more. The upper limit of the slide angle is not particularly limited, but is usually 65° or less.

[0047] <Rubber composition>

[0048] The diene polymer rubber of the present invention can be prepared into a rubber composition by adding a crosslinking agent.

[0049] As the crosslinking agent, for example, sulfur, sulfur-containing compounds such as sulfur halides, organic peroxides, quinone dioximes, organic polyamine compounds, alkylphenol resins having methylol groups, etc. can be cited. Among these, sulfur is preferably used. The amount of the crosslinking agent added is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 5 parts by weight, and particularly preferably 1 to 4 parts by weight relative to 100 parts by weight of the polymer component in the rubber composition.

[0050] In addition, the rubber composition of the present invention may also contain a filler, and examples of the filler include silica, calcium silicate, aluminum silicate, carbon black, calcium carbonate, talc, aluminum hydroxide, aluminum oxide, clay, and mica. Among these, carbon black and silica are preferred, and silica is more preferred, from the perspective of further improving the friction on ice and affinity for water of the obtained rubber cross-linked product. The fillers can be used alone or in combination of two or more.

[0051] As silica, for example, dry-process white carbon black, wet-process white carbon black, colloidal silica, precipitated silica, calcium silicate, aluminum silicate, etc. can be cited. Among these, wet-process white carbon black with hydrous silicic acid as the main component is preferred. In addition, a carbon-silica dual-phase filler in which silica is supported on the surface of carbon black can also be used. These silicas can be used alone or in combination of two or more. The nitrogen adsorption specific surface area of ​​the silica used (measured by the BET method according to ASTM D3037-81) is preferably 20 to 400 m 2 / g, more preferably 50 to 220 m 2 / g, particularly preferably 80 to 170 m 2 / g. In addition, the pH of silica is preferably 5-10.

[0052] Examples of carbon black include furnace black, acetylene black, thermal black, channel black, and graphite. Examples of channel black include EPC, MPC, and CC. Examples of furnace black include SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF. Examples of pyrolytic black include FT and MT. The carbon blacks may be used alone or in combination of two or more.

[0053] The amount of the filler added to the rubber composition of the present invention is preferably 5 to 90 parts by weight, more preferably 10 to 70 parts by weight, and even more preferably 20 to 65 parts by weight relative to 100 parts by weight of the polymer component in the rubber composition. By making the amount of the filler added within the above range, the processability of the rubber composition can be made sufficient, and the wear resistance, friction on ice and affinity for water of the obtained rubber cross-linked product can be further improved in a well-balanced manner.

[0054] From the viewpoint of further improving the cut resistance, reinforcement and low loss of the obtained rubber cross-linked product, a silane coupling agent may be further added to the rubber composition of the present invention. The silane coupling agent is not particularly limited, and various silane coupling agents can be used. In the present invention, sulfide-based, mercapto-based, protected mercapto-based (e.g., silane coupling agents having a carbonylthio group), thiocyanate-based, vinyl-based, amino-based, methacrylic-based, glycidoxy-based, nitro-based, epoxy-based or chlorine-based silane coupling agents can be preferably used. Specific examples of the silane coupling agent include bis(3-(triethoxysilyl)propyl)disulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(3-(triethoxysilyl)propyl)tetrasulfide, bis(3-triethoxysilylpropyl)polysulfide, γ-mercaptopropyltriethoxysilane, 3-[ethoxybis(3,6,9,12,15-pentaoxacosan-1-yloxy)silyl]-1-propanethiol, 3-octanoylthio-1-propyl-triethoxysilane, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, γ-trimethoxysilylpropylbenzothiazole tetrasulfide, 3-trimethoxysilylpropylbenzothiazole tetrasulfide, 3-thiocyanatepropyltriethoxysilane, vinyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, 3-trimethoxysilylpropylmethacrylate monosulfide, γ-glycidoxypropyltriethoxysilane, 3-nitropropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 3-chloropropyltrimethoxysilane, etc. In addition, NXT-Z100, NXT-Z30, NXT-Z45, NXT-Z60, NXT-Z45, NXT manufactured by Momentive Performance Materials, Si69, Si75, VP Si363 manufactured by Evonik Degussa, etc. can also be used. These silane coupling agents can be used alone or in combination of two or more. In addition, one or more of these silane coupling agents can be pre-oligomerized and used in an oligomerized state. The amount of the silane coupling agent added is preferably 0.1 to 30 parts by weight, more preferably 1 to 15 parts by weight relative to 100 parts by weight of the filler.

[0055] The rubber composition of the present invention may also contain other polymers in addition to the diene polymer rubber of the present invention. Other polymers include, for example, natural rubber (which may be modified natural rubber such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), grafted natural rubber, etc.), polyisoprene rubber, emulsion-polymerized styrene-butadiene copolymer rubber, solution-polymerized styrene-butadiene copolymer rubber, polybutadiene rubber (which may be high cis-BR or low cis-BR. In addition, it may be polybutadiene rubber containing crystalline fibers composed of 1,2-polybutadiene polymer), styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, styrene-isoprene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, acrylonitrile-styrene-butadiene copolymer rubber, butyl rubber (IIR), ethylene-propylene copolymer, chloroprene rubber, nitrile chloroprene rubber, and nitrile isoprene rubber, etc., except for the above-mentioned conjugated diene polymers. Among these, natural rubber, polyisoprene rubber, polybutadiene rubber and solution-polymerized styrene-butadiene copolymer rubber are preferred, and natural rubber and polybutadiene rubber are more preferred. These polymers can be used alone or in combination of two or more such as natural rubber and polybutadiene rubber, natural rubber and styrene-butadiene copolymer rubber.

[0056] Furthermore, in addition to the above-mentioned components, the rubber composition of the present invention may also contain required amounts of additives such as crosslinking accelerators, crosslinking activators, antioxidants, surfactants, processing oils, plasticizers, lubricants, and tackifiers, respectively, according to conventional methods.

[0057] When sulfur or a sulfur-containing compound is used as a crosslinking agent, it is preferred to use a crosslinking accelerator and a crosslinking activator together. As a crosslinking accelerator, for example: sulfonamide crosslinking accelerator; guanidine crosslinking accelerator; thiourea crosslinking accelerator; thiazole crosslinking accelerator; thiuram crosslinking accelerator; dithiocarbamic acid crosslinking accelerator; xanthate crosslinking accelerator, etc. Among these, a crosslinking accelerator containing a sulfonamide crosslinking accelerator is preferred. These crosslinking accelerators can be used alone or in combination of two or more. The amount of the crosslinking accelerator added is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 5 parts by weight, and particularly preferably 1 to 4 parts by weight relative to 100 parts by weight of the polymer component in the rubber composition.

[0058] As the crosslinking activator, for example, higher fatty acids such as stearic acid, zinc oxide, etc. can be cited. These crosslinking activators can be used alone or in combination of two or more. The amount of the crosslinking activator added is preferably 0.05 to 20 parts by weight, particularly preferably 0.5 to 15 parts by weight, relative to 100 parts by weight of the polymer component in the rubber composition.

[0059] In order to obtain the rubber composition of the present invention, the components can be kneaded according to a conventional method. For example, after kneading the components other than the heat-unstable components such as the crosslinking agent and the crosslinking accelerator with the polymer component containing the diene polymer rubber of the present invention, the heat-unstable components such as the crosslinking agent and the crosslinking accelerator can be mixed into the kneaded product to obtain the target composition. The kneading temperature of the components other than the heat-unstable components and the polymer component containing the diene polymer rubber of the present invention is preferably 80 to 200°C, more preferably 100 to 180°C, and the kneading time is preferably 30 seconds to 30 minutes. In addition, the mixing of the kneaded product and the heat-unstable components is usually carried out at a temperature below 100°C, preferably after cooling to a temperature below 80°C.

[0060] <Rubber cross-linked products>

[0061] A cross-linked rubber can be obtained by cross-linking the rubber composition containing the diene polymer rubber of the present invention.

[0062] The rubber cross-linked product of the present invention can be manufactured as follows: using the above-mentioned rubber composition containing the diene polymer rubber of the present invention, it is molded by a molding machine corresponding to the desired shape, such as an extruder, an injection molding machine, a compressor, a roller, etc., and the cross-linking reaction is carried out by heating to fix the shape as a rubber cross-linked product. In this case, cross-linking can be carried out after pre-molding, or it can be cross-linked at the same time as molding. The molding temperature is usually 10 to 200°C, preferably 20 to 120°C. The cross-linking temperature is usually 100 to 200°C, preferably 130 to 190°C, and the cross-linking time is usually 1 minute to 24 hours, preferably 2 minutes to 12 hours, and particularly preferably 3 minutes to 6 hours.

[0063] Furthermore, depending on the shape and size of the cross-linked rubber, even if the surface is cross-linked, the interior may not be sufficiently cross-linked. Therefore, further heating may be performed to perform secondary cross-linking.

[0064] As the heating method, any method generally used for crosslinking of rubber, such as press heating, steam heating, oven heating, and hot air heating, may be appropriately selected.

[0065] The cross-linked rubber of the present invention thus obtained is obtained by using the diene polymer rubber of the present invention, and therefore has excellent friction on ice and high affinity for water. Therefore, the cross-linked rubber of the present invention can be used for various purposes, such as materials for various parts of tires; materials for hoses, belts, mats, anti-vibration rubbers, and other various industrial products; impact resistance improvers for resins; resin film cushioning agents; shoe soles; rubber shoes; golf balls; toys, etc. In particular, the cross-linked rubber of the present invention can be used for various purposes, such as tires and shoe soles, by effectively utilizing its excellent friction on ice and affinity for water.

[0066] Example

[0067] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In addition, "parts" are based on weight unless otherwise specified.

[0068] The test methods performed in the present examples and comparative examples are as follows.

[0069] <Monomer composition, vinyl bond content>

[0070] The monomer composition of the diene polymer rubber and the amount of vinyl bonds (mol%) in the diene monomer unit were determined according to JIS K6239:2007. 1 It was determined by H-NMR method.

[0071] <Mooney viscosity of diene polymer rubber>

[0072] The Mooney viscosity (ML1+4) of the diene polymer rubber was measured in accordance with JIS K6300-1:2013 under the following conditions.

[0073] Test temperature: 100℃

[0074] Rotor type: L-shaped

[0075] ·Testing machine used: Shimadzu Corporation, Shimadzu Mooney Viscometer SMV-301

[0076] <Glass transition temperature (Tg) of diene polymer rubber>

[0077] The diene polymer rubber was measured using a differential scanning calorimeter (DSC, X-DSC7000 manufactured by Hitachi High-Technologies Corporation) by raising the temperature to -150°C to 40°C at 10°C / min to determine the glass transition temperature (Tg).

[0078] <Friction properties of cross-linked rubber on ice>

[0079] The rubber composition of each embodiment and comparative example was molded into a test piece with a diameter of 50 mm and a thickness of 10 mm, cross-linked at 160°C for 1 hour, and then the test piece was pressed on fixed ice and rotated. The friction force generated when the test piece was rotated was detected by a force sensor, and the dynamic friction coefficient μ was calculated from the detected friction force. In addition, the measurement temperature was -2°C and the surface pressure was 12 kgf / cm 2 The sample rotation circumferential speed is 20 cm / sec. The measurement results are expressed as an index when the dynamic friction coefficient μ of Comparative Example 1 is taken as 100. The larger the index value, the larger the dynamic friction coefficient μ, and the better the friction on ice (the higher the friction coefficient on ice, the better).

[0080] <Slip angle of cross-linked rubber>

[0081] The rubber composition of each embodiment and comparative example was molded into a 20 mm × 30 mm test plate (thickness: 2 mm), cross-linked at 160°C for 20 minutes, and then 2 μL of water was dripped onto the test plate. The test plate was gradually tilted at a uniform speed, and the angle at which the water droplet began to slide off was measured as the sliding angle (dynamic contact angle). The larger the sliding angle, the better the wettability with water and the higher the affinity for water. In addition, in Examples 4 to 6, it can be considered that since only diene polymer rubbers (A-1) to (A-3) are contained as rubber components, the sliding angles of the diene polymer rubbers (A-1) to (A-3) themselves are also of the same degree.

[0082] <Example 1>

[0083] 200 parts of ion exchange water, 4.5 parts of potassium disproportionate rosin acid / sodium fatty acid, 0.1 parts of potassium chloride, 10 parts of methoxyethyl acrylate and 0.3 parts of tert-dodecyl mercaptan (molecular weight modifier) ​​were added to the reactor in sequence, the gas inside was replaced with nitrogen three times, and then 90 parts of 1,3-butadiene were added. Then, the reactor was kept at 10°C, 0.1 parts of diisopropylbenzene hydroperoxide (polymerization initiator), appropriate amounts of reducing agent and chelating agent were added, and polymerization reaction was initiated while stirring. The polymerization reaction was continued while stirring, and when the polymerization conversion rate reached 75%, 0.2 parts of diethylhydroxylamine (polymerization terminator) was added to terminate the polymerization reaction. After the polymerization reaction was terminated, the residual monomer was removed under reduced pressure at a water temperature of 60°C, and then 0.5 parts of alkylated phenol as an antioxidant was added. Then, the obtained polymer latex was added to a calcium chloride aqueous solution, thereby coagulating to obtain a granular polymer. Then, the obtained pelletized polymer was taken out and washed with water, and then dried at 60° C. under reduced pressure to obtain a diene polymer rubber (A-1).

[0084] The obtained diene polymer rubber (A-1) had a 1,3-butadiene unit content of 91 wt%, a methoxyethyl acrylate unit content of 9 wt%, a vinyl bond content in the 1,3-butadiene unit of 16 mol%, a Mooney viscosity (ML1+4) of 55, and a glass transition temperature (Tg) of -76°C.

[0085] <Example 2>

[0086] A diene polymer rubber (A-2) was obtained by carrying out polymerization in the same manner as in Example 1 except that the amount of methoxyethyl acrylate and the amount of 1,3-butadiene used were changed to 20 parts and 80 parts, respectively.

[0087] The obtained diene polymer rubber (A-2) had a 1,3-butadiene unit content of 82 wt%, a methoxyethyl acrylate unit content of 18 wt%, a vinyl bond content in the 1,3-butadiene unit of 15 mol%, a Mooney viscosity (ML1+4) of 43, and a glass transition temperature (Tg) of -72°C.

[0088] <Example 3>

[0089] A diene polymer rubber (A-3) was obtained by carrying out polymerization in the same manner as in Example 1 except that the amount of methoxyethyl acrylate used was changed to 5 parts and the amount of 1,3-butadiene used was changed to 95 parts.

[0090] The obtained diene polymer rubber (A-3) had a 1,3-butadiene unit content of 95 wt%, a methoxyethyl acrylate unit content of 5 wt%, a vinyl bond content in the 1,3-butadiene unit of 16 mol%, a Mooney viscosity (ML1+4) of 65, and a glass transition temperature (Tg) of -78°C.

[0091] <Example 4>

[0092] 100 parts of the diene polymer rubber (A-1) obtained in Example 1 was masticated for 30 seconds in a Brabender mixer having a capacity of 250 ml, and then 50 parts of silica (manufactured by Tosoh Silicon Chemical Co., Ltd., trade name "Nipsil AQ") and 4 parts of a silane coupling agent: bis(3-triethoxysilylpropyl) polysulfide (manufactured by Shin-Etsu Chemical Co., Ltd.) were added, and kneading was performed for 1.5 minutes at a starting temperature of 110°C. Then, 3 parts of zinc oxide (zinc white), 2 parts of stearic acid, and 2 parts of an antioxidant: N-phenyl-N′-(1,3-dimethylbutyl)-p-phenylenediamine (manufactured by Ouchi Shinko Chemical Co., Ltd., trade name "NOCRAC 6C") were added, and kneading was further performed for 2.5 minutes, and the kneaded product was discharged from the mixer. The temperature of the kneaded product at the end of kneading was 150°C. Then, the obtained kneaded product was cooled to room temperature, kneaded again in a Brabender mixer at a starting temperature of 110° C. for 2 minutes, and then discharged from the mixer. Next, 1.4 parts of sulfur and 1 part of a crosslinking accelerator: N-cyclohexyl-2-benzothiazolesulfenamide (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name "NOCCELER CZ-G") were added to the obtained kneaded product using an open roll at 50° C., and these were kneaded to obtain a sheet-like rubber composition.

[0093] Then, the obtained rubber composition was used to evaluate the friction property on ice of the cross-linked rubber and the sliding angle of the cross-linked rubber.

[0094] <Example 5>

[0095] A rubber composition was obtained in the same manner as in Example 4 except that 100 parts of the diene polymer rubber (A-2) obtained in Example 2 was used instead of 100 parts of the diene polymer rubber (A-1) obtained in Example 1, and evaluation was performed in the same manner. The results are shown in Table 1.

[0096] <Example 6>

[0097] A rubber composition was obtained in the same manner as in Example 4 except that 100 parts of the diene polymer rubber (A-3) obtained in Example 3 was used instead of 100 parts of the diene polymer rubber (A-1) obtained in Example 1, and evaluation was performed in the same manner. The results are shown in Table 1.

[0098] <Example 7>

[0099] A rubber composition was obtained in the same manner as in Example 4 except that the amount of the diene polymer rubber (A-1) obtained in Example 1 was changed from 100 parts to 50 parts, and 25 parts of butadiene rubber (manufactured by UBE Corporation, trade name "UBEPOL BR150L") and 25 parts of natural rubber were further added, and the rubber composition was evaluated in the same manner. The results are shown in Table 1. The timing of adding the butadiene rubber and the natural rubber was the same as that of the diene polymer rubber (A-1). In Example 7, after the diene polymer rubber (A-1), butadiene rubber and natural rubber were masticated, various additives were added to obtain a rubber composition.

[0100] <Comparative Example 1>

[0101] A rubber composition was obtained in the same manner as in Example 4, except that 50 parts of butadiene rubber (manufactured by UBE Corporation, trade name "UBEPOL BR150L") and 50 parts of natural rubber were used instead of 100 parts of the diene polymer rubber (A-1) obtained in Example 1, and the rubber composition was evaluated in the same manner. The results are shown in Table 1. In Comparative Example 1, after butadiene rubber and natural rubber were masticated, various additives were added to obtain a rubber composition.

[0102] [Table 1]

[0103] Table 1

[0104]

[0105] As shown in Table 1, the cross-linked rubber obtained by using the diene polymer rubber containing 1 to 40% by weight of the (meth)acrylate monomer unit has excellent friction on ice, a large slide angle, and high affinity for water (Examples 4 to 7).

Claims

1. A diene polymer rubber, which is a conjugated diene polymer rubber containing a diene monomer unit and a (meth)acrylate monomer unit, The content ratio of the (meth)acrylic acid ester monomer unit is 1 to 40% by weight.

2. The diene polymer rubber according to claim 1, characterized in that The glass transition temperature of the diene polymer rubber is -100 to -50°C.

3. The diene polymer rubber according to claim 1 or 2, characterized in that: The (meth)acrylate monomer unit is an alkoxyalkyl (meth)acrylate monomer unit.

4. The diene polymer rubber according to any one of claims 1 to 3, characterized in that The sliding angle is 38° or more.

5. A method for producing a diene polymer rubber, the method comprising producing the diene polymer rubber according to any one of claims 1 to 4, The method for producing the diene polymer rubber comprises the following steps: A step of polymerizing a monomer mixture containing a diene monomer and a (meth)acrylic acid ester monomer in an aqueous medium in the presence of an emulsifier.

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