Hydrogenated block copolymer, viscosity index improver, oil composition, and cable gel

Abstract

To provide a hydrogenated block copolymer that is suitable as a material for a viscosity index improver, an oil composition, and a cable gel, and that exhibits superior solubility in a base oil.SOLUTION: A hydrogenated block copolymer comprising: one polymer block (A) mainly composed of a vinyl aromatic monomer unit having a molecular weight of 7000; and a polymer block (B) containing at least one conjugated diene monomer unit and a vinyl aromatic monomer unit; wherein the content of the vinyl aromatic monomer unit in the hydrogenated block copolymer is 5.0 mass% or more and 37.5 mass% or less; the content of the vinyl aromatic monomer unit in the polymer block (B) is 1.0 mass% or more and 45.0 mass% or less; and the 1,2-vinyl bond content in the conjugated diene monomer unit is 50.0 mol% or more and 80 mol% or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a hydrogenated block copolymer, a viscosity index improver, an oil composition, and a cable gel.

Background Art

[0002] Cables such as optical fiber cables and electric wires cables are generally provided with a buffer material of a gel composition around the core wire of the optical fiber for the purpose of protecting the internal optical fiber from external interference and preventing water from entering when the cable is damaged. The buffer material of the gel composition used for such applications is called a cable gel, and has the property of thixotropy (hereinafter referred to as thixotropy) in which it exhibits liquid properties under shear stress and can be easily filled into the cable, and exhibits solid properties under non-shear stress so that the filler does not flow out from the inside when the cable is damaged.

[0003] Various compositions have been conventionally disclosed as such cable gels. For example, Patent Document 1 discloses a technique in which 1,3-butadiene is hydrogenated, a polymer having a vinyl bond amount in a predetermined range is mixed with a base oil to reduce crystallinity, suppress elastic behavior, and obtain an oil composition having thixotropy, and this is used as a cable gel for an optical fiber cable.

[0004] Conventionally, a viscosity index improver for engine oil has been known as a modifier for engine oil. This viscosity index improver is usually used in the state of an oil composition added in a small amount to a base oil, and when used in engine oil, it can improve fuel efficiency and prevent engine wear. For example, Patent Document 2 describes a viscosity index improver containing a polymer having a controlled distribution block of vinyl aromatic monomer units and conjugated diene monomer units and a base oil, wherein the hydrogenated conjugated diene monomer units of the polymer are reduced and the crystal segments are eliminated to prevent a decrease in the ability of the pour point depressant, and the viscosity index improver is composed of an oil composition.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, as a result of the study by the present inventors, the polymers constituting the oil compositions described in Patent Documents 1 and 2 have a problem that their solubility in the base oil is insufficient.

[0007] Therefore, an object of the present invention is to obtain a hydrogenated block copolymer that is excellent in solubility in a base oil and useful as a material for a viscosity index improver, an oil composition, and a cable gel.

Means for Solving the Problems

[0008] As a result of intensive studies to solve the above-described problems of the prior art, the present inventors have found that a hydrogenated block copolymer having a specific structure exhibits sufficient compatibility with a base oil, and have completed the present invention. That is, the present invention is as follows.

[0009] 〔1〕 One polymer block (A) mainly composed of vinyl aromatic monomer units having a molecular weight of 7000 or more, and At least one polymer block (B) containing a conjugated diene monomer unit and a vinyl aromatic monomer unit, which is a hydrogenated block copolymer having a content of vinyl aromatic monomer units in the hydrogenated block copolymer of 5.0% by mass or more and 37.5% by mass or less, the vinyl aromatic monomer units in the polymer block (B) being 1.0% by mass or more and 45.0% by mass or less, the amount of 1,2 - vinyl bonds in the conjugated diene monomer units being 50.0 mol% or more and 80 mol% or less, a hydrogenated block copolymer. [2] the hydrogenation rate of the conjugated diene monomer units being 60.0 mol% or more and 100 mol% or less, the hydrogenated block copolymer according to [1] above. [3] the conjugated diene monomer units being derived from butadiene, the hydrogenated block copolymer according to [1] or [2] above. [4] having a weight average molecular weight of 20,000 to 500,000, the hydrogenated block copolymer according to any one of [1] to [3] above. [5] further having a polymer block (C) with a higher conjugated diene monomer ratio than the polymer block (B), the hydrogenated block copolymer according to any one of [1] to [4] above. [6] a viscosity index improver containing the hydrogenated block copolymer according to any one of [1] to [5] above. [7] the hydrogenated block copolymer according to any one of [1] to [5] above, a base oil, and having a content of the hydrogenated block copolymer of 0.1% by mass or more and 40.0% by mass or less, an oil composition. [8] wherein the base oil is mineral oil and / or synthetic oil, the oil composition according to [7] above. [9] The oil composition according to the above [7] or [8], which is a cable gel. [Advantages of the Invention]

[0010] According to the present invention, a hydrogenated block copolymer is obtained which is excellent in solubility in base oil and useful as a viscosity index improver, an oil composition, and a material for a cable gel. [Embodiments for Carrying Out the Invention]

[0011] Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as "the present embodiments") will be described in detail. It should be noted that the following present embodiments are examples for explaining the present invention, and the present invention is not limited to the following embodiments. The present invention can be appropriately modified and implemented within the scope of its gist.

[0012] (Hydrogenated block copolymer) The block copolymer of the present embodiment is one polymer block (A) mainly composed of vinyl aromatic monomer units having a molecular weight of 7000 or more, and at least one polymer block (B) containing a conjugated diene monomer unit and a vinyl aromatic monomer unit, and has the content of aromatic vinyl monomer units in the hydrogenated block copolymer is 5.0% by mass or more and 37.5% by mass or less, the vinyl aromatic monomer units in the polymer block (B) are 1.0% by mass or more and 45.0% by mass or less, the amount of 1,2-vinyl bonds in the conjugated diene monomer units is 50.0 mol% or more and 80.0 mol% or less.

[0013] "Vinyl aromatic monomer unit" refers to a structure in a polymer resulting from the polymerization of a vinyl aromatic compound, which shows a structure corresponding to one molecule of the vinyl aromatic compound. "Conjugated diene monomer unit" refers to a structure in a polymer resulting from the polymerization of a conjugated diene compound, which shows a structure corresponding to one molecule of the conjugated diene compound.

[0014] (Polymer block (A)) The hydrogenated block copolymer of the present embodiment has a polymer block (A) mainly composed of vinyl aromatic monomer units (hereinafter, may be referred to as polymer block (A)). Here, "mainly composed of vinyl aromatic monomer units" in the polymer block (A) means that the amount of vinyl aromatic monomer units contained in the polymer block (A) is 75.0% by mass or more. The content of vinyl aromatic monomer units in the polymer block (A) is preferably 80.0% by mass or more, more preferably 90.0% by mass or more.

[0015] (Polymer block (A)) The hydrogenated block copolymer of the present embodiment has one polymer block (A) mainly composed of vinyl aromatic monomer units having a molecular weight of 7000 or more. When the molecular weight in the polymer block (A) is above the above, it has excellent blocking resistance, and by having one, it has excellent thixotropic properties.

[0016] (Polymer block (B)) The hydrogenated block copolymer of the present embodiment has at least one polymer block (B) containing conjugated diene monomer units and vinyl aromatic monomer units (hereinafter, may be referred to as polymer block (B)). The content of vinyl aromatic monomer units in the polymer block (B) is 1.0% by mass or more, preferably 7.0% by mass or more, more preferably 15.0% by mass or more, and still more preferably 23.0% by mass or more. Also, the content of vinyl aromatic monomer units in the polymer block (B) is 45% by mass or less, preferably 42.0% by mass or less, more preferably 39.0% by mass or less, and still more preferably 36.0% by mass or less. When the content of the vinyl aromatic monomer unit in the polymer block (B) is within the above range, the hydrogenated block copolymer of the present embodiment and paraffin and naphthene in the base oil described later have excellent compatibility and tend to improve the solubility in oil. From the above viewpoints, the content of the conjugated diene monomer unit in the polymer block (B) is preferably 55.0% by mass or more and 99.0% by mass or less, preferably 58.0% by mass or more and 93.0% by mass or less, more preferably 61.0% by mass or more and 85.0% by mass or less, and still more preferably 64.0% by mass or more and 77.0% by mass or less. The content of the vinyl aromatic monomer unit in the polymer block (B) can be controlled within the above numerical range by adjusting the addition amount and addition timing of the vinyl aromatic monomer in the polymerization step.

[0017] (Vinyl aromatic monomer unit) The "vinyl aromatic monomer unit" constituting the hydrogenated block copolymer of the present embodiment is derived from a "vinyl aromatic compound". The vinyl aromatic compound is not limited to the following, and examples thereof include styrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylethylene, n,n-dimethyl-p-aminoethylstyrene, n,n-diethyl-p-aminoethylstyrene, and the like. Among these, from the viewpoints of availability and productivity, styrene, α-methylstyrene, and p-methylstyrene are preferable. Among these, styrene is particularly preferable. These may be used alone or in combination of two or more.

[0018] (Conjugated diene monomer unit) The "conjugated diene monomer unit" constituting the hydrogenated block copolymer of the present embodiment is derived from a "conjugated diene compound". A conjugated diene compound is a diolefin having a pair of conjugated double bonds. Examples of the conjugated diene compound include, but are not limited to, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, and farnesene. Among these, from the viewpoint of easy industrial availability, 1,3-butadiene and isoprene are preferable, and 1,3-butadiene is particularly preferable from the viewpoint of thermal stability. These may be used alone or in combination of two or more.

[0019] (Content of vinyl aromatic monomer units in the hydrogenated block copolymer) The hydrogenated block copolymer of the present embodiment has a content of vinyl aromatic monomer units of 5.0% by mass or more, preferably 10.0% by mass or more, more preferably 15.0% by mass or more, and still more preferably 20.0% by mass or more. When the content of vinyl aromatic monomer units is 5% by mass or more, the finishability and blocking resistance tend to be good. In addition, the content of vinyl aromatic monomer units in the hydrogenated block copolymer of the present embodiment is 37.5% by mass or less, preferably 37.0% by mass or less, more preferably 36.5% by mass or less, and still more preferably 36.0% by mass or less. When the content of vinyl aromatic monomer units is 37.5% by mass or less, the entanglement of the molecular chains derived from the conjugated diene becomes a certain amount or more, and the hydrogenated block copolymer tends to be excellent in maintaining the shape under non-shearing stress of thixotropy. The content of vinyl aromatic monomer units in the hydrogenated block copolymer can be measured by the method described in the examples described later. The content of vinyl aromatic monomer units in the hydrogenated block copolymer can be controlled within the above numerical range by adjusting the addition amount of the vinyl aromatic compound in the polymerization step.

[0020] (Amount of 1,2-vinyl bonds) The amount of 1,2-vinyl bonds in the conjugated diene monomer units constituting the hydrogenated block copolymer of the present embodiment is 50.0 mol% or more, preferably 52.0 mol% or more, more preferably 54.0 mol% or more, and still more preferably 56.0 mol% or more. When the amount of 1,2-vinyl bonds is 50.0 mol% or more, crystallization tends not to occur. By suppressing the occurrence of crystallization, it tends to exhibit good fluidity under high shear of thixotropy. Also, the amount of 1,2-vinyl bonds is 80.0 mol% or less, preferably 78.0 mol% or less, more preferably 76.0 mol% or less, and still more preferably 75.0 mol% or less. When the amount of 1,2-vinyl bonds is 80.0 mol% or less, it can be produced without the need to adjust the polymerization temperature to a low temperature, which is practically preferable. The amount of 1,2-vinyl bonds in the hydrogenated block copolymer of the present embodiment can be measured by the method described in the examples below. The microstructure (ratio of cis, trans, vinyl) of the conjugated diene monomer units of the block copolymer, which is the state before hydrogenation of the hydrogenated block copolymer of the present embodiment, can be arbitrarily controlled by using polar compounds and the like described below.

[0021] (Weight average molecular weight) The hydrogenated block copolymer of the present embodiment preferably has a weight average molecular weight of 20,000 or more, more preferably 50,000 or more, still more preferably 80,000 or more, and still more preferably 100,000 or more. When the weight average molecular weight is 20,000 or more, the finishability and blocking resistance tend to be good. Also, the weight average molecular weight in the hydrogenated block copolymer of the present embodiment is preferably 500,000 or less, more preferably 400,000 or less, still more preferably 350,000 or less, and still more preferably 300,000 or less. When the weight average molecular weight is 500,000 or less, it is possible to prevent the molecular weight from greatly fluctuating due to the influence of deactivating components contained in the solvent or monomer, and it tends to be excellent in production stability. The weight average molecular weight of the hydrogenated block copolymer can be measured by the method described in the examples below. The weight average molecular weight of the hydrogenated block copolymer can be controlled within the above-described numerical range by adjusting the polymerization conditions such as the amount of monomer added, the timing of addition, the polymerization time, and the polymerization temperature in the polymerization step.

[0022] (Hydrogenation rate) The hydrogenation rate (hydrogenation ratio) of the double bond based on the conjugated diene monomer unit in the hydrogenated block copolymer of the present embodiment is preferably 60.0 mol% or more, more preferably 70.0 mol% or more, still more preferably 80.0 mol% or more, and still more preferably 90.0 mol% or more. When the hydrogenation rate is 60.0 mol% or more, it tends to have excellent thermal stability. Also, the hydrogenation rate is preferably 100 mol% or less, and more preferably 99.5 mol% or less, which is preferable in production from the viewpoint of suppressing a decrease in production efficiency. The hydrogenation rate can be measured by the method described in the examples below. The hydrogenation rate can be controlled within the above numerical range by adjusting the amount of hydrogenation catalyst and the hydrogenation reaction time.

[0023] (Polymer block (C)) The hydrogenated block copolymer of the present embodiment may have a polymer block (C) (hereinafter sometimes referred to as polymer block (C)) having a higher content ratio of conjugated diene monomer units than the polymer block (B). The content of the polymer block (C) in the hydrogenated block copolymer of the present embodiment is preferably 5.0% by mass or more, more preferably 25.0% by mass or more, still more preferably 30.0% by mass or more, and still more preferably 40.0% by mass or more. Increasing the content of the conjugated diene monomer tends to improve thixotropy.

[0024] (Amount of vinyl bonds in polymer block (C)) The polymer block (C) preferably has a 1,2-vinyl bond content of 50.0 mol% or more, more preferably 52.0 mol% or more, still more preferably 54.0 mol% or more, and even more preferably 56.0 mol% or more. When the vinyl bond content of the polymer block (C) is within the above range, it tends not to exhibit crystallinity in the 1,4-cis and trans structures and tends to exhibit good fluidity under highly thixotropic high shear conditions. The 1,2-vinyl bond content in the polymer block (C) is preferably 80.0 mol% or less, more preferably 78.0 mol% or less, still more preferably 76.0 mol% or less, and even more preferably 75.0 mol% or less. When the 1,2-vinyl bond content of the polymer block (C) is 80.0 mol% or less, it is not necessary to adjust the polymerization temperature of the conjugated diene to a low temperature, which is preferable in production. The vinyl bond content of the polymer block (C) can be arbitrarily controlled by using a polar compound or the like described later.

[0025] (Content of conjugated diene monomer units in the hydrogenated block copolymer) The content of the conjugated diene monomer units in the hydrogenated block copolymer of the present embodiment is preferably 80.0 mass% or less, more preferably 70.0 mass% or less, still more preferably 65.0 mass% or less, and even more preferably 60.0 mass% or less. When it is within the above range, in the oil composition described later, it has excellent compatibility with an oil having a high paraffin ratio in the base oil (for example, containing 50.0 mass% or more).

[0026] (Block arrangement of the hydrogenated block copolymer) The structure of the hydrogenated block copolymer of the present embodiment is not particularly limited, and any structure may be used as long as it has one of the polymer blocks (A) and at least one of the polymer blocks (B). When a plurality of polymer blocks (B) are included, the polymer blocks (B) may be the same or different. Further, it may have the polymer block (C). When a plurality of polymer blocks (C) are included, the polymer blocks (C) may be the same or different. Hereinafter, preferred structural examples will be shown. A-B (1) A-B-C (2) A-C-B (3) B-A-B (4) C-A-B (5) B-A-B-C (6) B-A-C-B (7) C-A-B-C (8) C-A-C-B (9) A-B-C-B (10) A-C-B-C (11) In the formulas (1) to (11), each A independently represents a polymer block (A) mainly composed of vinyl aromatic monomer units, each B independently represents a polymer block (B) containing conjugated diene monomer units and vinyl aromatic monomer units, and each C independently represents a polymer block (C) mainly composed of conjugated diene monomer units having more conjugated diene monomer units than the polymer block (B). From the viewpoint of productivity, it preferably has the structure represented by the formulas (1) to (5), and more preferably has the structure represented by the formula (1) or (2).

[0027] (Method for producing hydrogenated block copolymer) The hydrogenated block copolymer of the present embodiment can be produced, for example, by performing polymerization using an organic alkali metal compound as a polymerization initiator in an organic solvent to obtain a block copolymer and then performing a hydrogenation reaction.

[0028] As the polymerization mode, it may be batch polymerization, continuous polymerization, or a combination thereof. From the viewpoint of obtaining a block copolymer with a narrow molecular weight distribution, the batch polymerization method is preferred.

[0029] The coincidence temperature is generally from 0°C to 150°C, preferably from 20°C to 120°C, and more preferably from 40°C to 100°C.

[0030] The polymerization time varies depending on the target block copolymer, but is usually within 24 hours, preferably from 0.1 hour to 10 hours. From the viewpoint of obtaining a block copolymer with a narrow molecular weight distribution and high strength, it is more preferably from 0.5 hour to 3.0 hours.

[0031] The polymerization pressure may be within a range sufficient to maintain nitrogen and the solvent in the liquid phase, and is not particularly limited. It is preferable that impurities such as water, oxygen, and carbon dioxide gas that inactivate the polymerization initiator and the living polymer do not exist in the polymerization system.

[0032] Examples of the organic solvent include, but are not limited to, aliphatic hydrocarbons such as n-butane, isobutane, n-pentane, n-hexane, n-heptane, and n-octane; alicyclic hydrocarbons such as cyclohexane, cycloheptane, and methylcyclopentane; and aromatic hydrocarbons such as benzene, xylene, toluene, and ethylbenzene.

[0033] As the organic alkali metal compound as the polymerization initiator, an organic lithium compound is preferable. Examples of the organic lithium compound include, but are not limited to, organic monolithium compounds, organic dilithium compounds, and organic polylithium compounds. Specifically, ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, t-butyl lithium, phenyl lithium, hexamethylene dilithium, butadienyl lithium, and isopropenyl dilithium can be mentioned. Among these, from the viewpoint of polymerization activity, n-butyl lithium and sec-butyl lithium are preferable.

[0034] The amount of the organic alkali metal compound used as the polymerization initiator varies depending on the molecular weight of the target block copolymer, but generally, it is preferably in the range of 0.01 phm to 0.5 phm (parts by mass per 100 parts by mass of the monomer), more preferably in the range of 0.03 phm to 0.3 phm, and even more preferably in the range of 0.05 phm to 0.15 phm.

[0035] The total amount of the 1,2-bond and 3,4-bond of the conjugated diene monomer unit before hydrogenation of the hydrogenated block copolymer of the present embodiment can be controlled by using a Lewis base (e.g., ether, amine, etc.). The amount of the Lewis base used is adjusted according to the ratio of the target 1,2-bond and 3,4-bond. Further, by adding the Lewis base and the metal alkoxide described below in two or more conditions, a block copolymer having different ratios of 1,2-bond and 3,4-bond can be produced in the polymer block mainly composed of the conjugated diene monomer unit.

[0036] Examples of the Lewis base include, but are not limited to, ether compounds, ether compounds having two or more oxygen atoms, and tertiary amine compounds.

[0037] Examples of the tertiary amine compound include, but are not limited to, pyridine, N,N,N’,N’-tetramethylethylenediamine, tributylamine, tetramethylpropanediamine, 1,2-dipiperidinoethane, and bis[2-(N,N-dimethylamino)ethyl]ether. These may be used alone or in combination of two or more. As the tertiary amine compound, a compound having two amines is preferable. Further, among them, those having a symmetric structure in the molecule are more preferable, and N,N,N’,N’-tetramethylethylenediamine, bis[2-(N,N-dimethylamino)ethyl]ether, and 1,2-dipiperidinoethane are even more preferable.

[0038]

[0039] ​ In the production process of the hydrogenated block copolymer of the present embodiment, polymerization may be carried out in the coexistence of the above-described Lewis base, organolithium compound, and alkali metal alkoxide. Here, the alkali metal alkoxide is a compound represented by the general formula MOR (wherein M is an alkali metal and R is an alkyl group).

[0040] From the viewpoints of a high ratio of 1,2-bonds and 3,4-bonds, a narrow molecular weight distribution, and a high polymerization rate, the alkali metal of the alkali metal alkoxide is preferably sodium or potassium.

[0041] The alkali metal alkoxide is not limited to the following, but for example, sodium alkoxide, lithium alkoxide, and potassium alkoxide having an alkyl group with 2 to 12 carbon atoms are preferable, and more preferably, sodium alkoxide or potassium alkoxide having an alkyl group with 3 to 6 carbon atoms, and still more preferably, sodium -t- butoxide, sodium -t- pentoxide, potassium -t- butoxide, and potassium -t- pentoxide. Among these, sodium -t- butoxide and sodium -t- pentoxide, which are sodium alkoxides, are even more preferable.

[0042] In the production process of the hydrogenated block copolymer of the present embodiment, when polymerization is carried out in the coexistence of a Lewis base, an organolithium compound, and an alkali metal alkoxide, the molar ratio of the Lewis base to the organolithium compound (Lewis base / organolithium compound) and the molar ratio of the alkali metal alkoxide to the organolithium compound (alkali metal alkoxide / organolithium compound) are preferably made to coexist as the molar ratios shown below. The Lewis base / organolithium compound is less than 0.2 to 3.0, and the alkali metal alkoxide / organolithium compound is 0.3 or less.

[0043] In the polymerization process, the molar ratio of the Lewis base to the organolithium compound is more preferably 0.5 or more from the viewpoints of a high ratio of 1,2-bonds and 3,4-bonds and a high polymerization rate, more preferably 2.5 or less from the viewpoints of a narrow molecular weight distribution and a high hydrogenation activity, and even more preferably in the range of 0.8 or more and 2.0 or less.

[0044] In addition, the molar ratio of the alkali metal alkoxide to the organolithium compound is more preferably 0.2 or less from the viewpoints of a narrow molecular weight distribution and a high hydrogenation activity, even more preferably 0.1 or less, and even more preferably 0.08 or less.

[0045] Furthermore, the molar ratio of the alkali metal alkoxide to the Lewis base is preferably 0.1 or less, more preferably 0.08 or less, even more preferably 0.06 or less, and even more preferably 0.05 or less from the viewpoints of achieving a narrow molecular weight distribution and obtaining a high hydrogenation activity.

[0046] In the process for producing the hydrogenated block copolymer of the present embodiment, the hydrogenation method is not particularly limited. For example, the block copolymer obtained as described above is supplied with hydrogen in the presence of a hydrogenation catalyst and hydrogenated to obtain a hydrogenated block copolymer in which the double bond residues of the conjugated diene monomer units are hydrogenated.

[0047] When the polymerization process and the hydrogenation process are carried out in an inert hydrocarbon solvent, for example, the inert hydrocarbon solvent can be removed to isolate the hydrogenated block copolymer. The method for removing the specific solvent is not particularly limited, and examples include steam stripping. By steam stripping, a hydrate cake can be obtained, and the obtained hydrate cake can be dried to obtain a hydrogenated block copolymer. When the hydrogenated block copolymer is in the form of a cake or powder, the mixing time can be shortened when producing the oil composition described later, and the oil composition can be efficiently produced in a short time.

[0048] In steam stripping, it is preferable to use a surfactant as the flocculant. Examples of such surfactants include, but are not limited to, anionic surfactants, cationic surfactants, and nonionic surfactants. These surfactants can generally be added to the water in the stripping zone at 0.1 ppm to 3000 ppm. In addition to the surfactant, water-soluble salts of metals such as Li, Na, Mg, Ca, Al, Zn, etc. can also be used as dispersion aids for the flocs.

[0049] The concentration of the flocculent hydrogenated block copolymer dispersed in water obtained through the polymerization step of the hydrogenated block copolymer and the steam stripping is generally 0.1% by mass to 20% by mass (ratio to the water in the stripping zone). Within this range, flocs with good particle sizes can be obtained without causing operational problems. It is preferable to adjust the water content of the flocculent hydrogenated block copolymer to 1% by mass to 30% by mass by dehydration, and then dry it until the water content becomes 1% by mass or less.

[0050] In the dehydration step of the flocs, dehydration can be performed using a compression water squeezer such as a roll, Banbury dehydrator, or screw extruder type squeezing dehydrator, or dehydration and drying can be performed simultaneously using a conveyor or a box-type hot air dryer.

[0051] The particle sizes of the flocs and the powder are preferably a volume average particle size of 1000 μm or less, more preferably 700 μm or less, even more preferably 600 μm or less, and even more preferably 500 μm or less. Within the above range, the solubility in the base oil in the oil composition described later will be excellent.

[0052] In the method for producing a hydrogenated block copolymer of the present embodiment, a step of deashing metals derived from a polymerization initiator or the like can be adopted as necessary. Further, in the method for producing a hydrogenated block copolymer of the present embodiment, a step of adding an antioxidant, a neutralizing agent, a surfactant, etc. can also be adopted as necessary.

[0053] Examples of the antioxidant include, but are not limited to, hindered phenol compounds, phosphorus compounds, sulfur compounds, etc. These may be used alone or in combination of two or more. Examples of the hindered phenol compounds include, but are not limited to, 2,6-di-t-butyl-4-methylphenol, N-octadecyl-3-(4'-hydroxy-3',5'-di-t-butylphenyl)propionate, [octadecyl-3-(3,5-dibutyl-t-butyl-4-hydroxyphenyl)propionate], 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 2,4-bis[(octylthio)methyl]-o-cresol, 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate, 2,4-di-t-amyl-6-[1-(3,5-di-t-amyl-2-hydroxyphenyl)ethyl]phenyl acrylate, 2-[1-(2-hydroxy-3,5-di-t-pentylphenyl)]acrylate, etc. Examples of the phosphorus compounds and sulfur compounds include, but are not limited to, 3,3'- thiodipropionate, 2-mercaptobenzimidazole, 4,6-bis(octylthiomethyl)-o-cresol, thiodiethylene bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], dilauryl thiodipropionate, lauryl stearyl thiodipropionate pentaerythritol-tetrakis(6-laurylthiopropionate), tris(nonylphenyl) phosphite, tris(2,4-di-T-butylphenyl) phosphite, etc.

[0054] The addition amount of the antioxidant is preferably 0.01 to 1 part by mass, more preferably 0.05 to 0.5 part by mass, and still more preferably 0.1 to 0.4 part by mass with respect to 100 parts by mass of the hydrogenated block copolymer.

[0055] Examples of the neutralizing agent include, but are not limited to, various metal stearates, hydrotalcite, benzoic acid, etc.

[0056] Examples of the surfactant include, but are not limited to, anionic surfactants, nonionic surfactants, cationic surfactants, etc. Examples of the anionic surfactant include, but are not limited to, fatty acid salts, alkyl sulfate esters, alkylaryl sulfonates, etc. Examples of the nonionic surfactant include, but are not limited to, polyoxyethylene alkyl ether, polyoxyethylene alkylaryl ether, etc. Examples of the cationic surfactant include, but are not limited to, alkylamine salts, quaternary ammonium salts, etc.

[0057] The hydrogenated block copolymer of the present embodiment can be blended with an anti-blocking agent in its clam for the purpose of preventing blocking, if necessary.

[0058] Examples of the anti-blocking agent include, but are not limited to, calcium stearate, magnesium stearate, zinc stearate, polyethylene, polypropylene, ethylene bisstearylamide, talc, amorphous silica, etc.

[0059] The blending amount of the anti-blocking agent is preferably 500 to 10000 ppm with respect to the hydrogenated block copolymer, and more preferably 1000 to 7000 ppm with respect to the hydrogenated block copolymer. The anti-blocking agent is preferably blended in a state of adhering to the surface of the clam, but may partially be included inside the clam.

[0060] (Viscosity Index Improver) The viscosity index improver of the present embodiment contains the hydrogenated block copolymer of the present embodiment. The viscosity index improver of the present embodiment may contain a heat stabilizer, if necessary. The hydrogenated block copolymer of the present embodiment has a viscosity preferable as a viscosity index improver and excellent solubility in a base oil described later. By adding it to the base oil, an oil composition is formed, and by using such an oil composition as a lubricating oil, an effect of reducing the viscosity change of the lubricating oil accompanying temperature change is exhibited. For example, by using the lubricating oil containing the viscosity index improver of the present embodiment as engine oil, effects of improving fuel efficiency and preventing engine wear can be obtained.

[0061] (Oil composition) The oil composition of the present embodiment contains the hydrogenated block copolymer of the present embodiment described above and a base oil. The content of the hydrogenated block copolymer in the oil composition of the present embodiment is 0.1% by mass or more and 40.0% by mass or less with respect to the total 100% by mass of the base oil and the hydrogenated block copolymer.

[0062] The oil composition of the present embodiment can be used as a viscosity index improver. When the oil composition of the present embodiment is used as a viscosity index improver, the content of the hydrogenated block copolymer is 0.1% by mass or more, preferably 0.2% by mass or more, and more preferably 0.5% by mass or more. When the content of the hydrogenated block copolymer is 0.1% by mass or more, an excellent viscosity index improving effect is exhibited. Further, it is preferably 7.0% by mass or less, more preferably 5.0% by mass or less, and still more preferably 2.0% by mass or less. When the content of the hydrogenated block copolymer is 7.0% by mass or less, the oil composition of the present embodiment shows a viscosity suitable for, for example, engine oil as a viscosity index improver. In the region where the addition amount is less than about 7.0% by mass, the thixotropy of the hydrogenated block copolymer does not appear, so it can be suitably used as a viscosity index improver (oil modification). As described later, in the region where the addition amount is more than that, thixotropy appears, so it is suitable when used as a cable gel, for example.

[0063] (Cable gel) The oil composition of the present embodiment can be used as a cable gel. When the oil composition of the present embodiment is used as a cable gel, the content of the hydrogenated block copolymer is preferably 6.0% by mass or more, more preferably 7.0% by mass or more, and still more preferably 8.0% by mass, based on 100% by mass of the total of the base oil and the hydrogenated block copolymer. When it is within the above range, it will have excellent thixotropic properties. Also, it is preferably 40.0% by mass or less, more preferably 20.0% by mass or less, still more preferably 15.0% by mass or less, and even more preferably 10.0% by mass or less. When it is within the above range, the oil composition can be easily filled into a protective tube or a cable during the manufacture of an optical fiber cable.

[0064] The cable gel of the present embodiment is composed of the oil composition of the present embodiment, and a heat stabilizer may be added as necessary. The oil composition of the present embodiment has a preferable viscosity as a cable gel, and the base oil and the hydrogenated block copolymer have excellent solubility. The oil composition can be easily filled into a protective tube or a cable during the manufacture of a cable, shows the property that the oil composition does not flow out from the inside even when the protective tube or the cable is damaged, and can further prevent the intrusion of water into the inside. Therefore, it is suitable as a cable gel for an optical fiber cable, an electric wire cable, etc.

[0065] (Base oil constituting the oil composition) Examples of the base oil contained in the oil composition of the present embodiment include mineral oil and synthetic oil. Examples of the mineral oil include paraffinic mineral oil and naphthenic mineral oil obtained by ordinary refining methods such as solvent refining and hydrorefining, wax produced by the Fischer-Tropsch process (gas-to-liquid wax), and mineral oil produced by isomerizing wax. Examples of the synthetic oil include hydrocarbon synthetic oils, ether synthetic oils, etc. Examples of the hydrocarbon synthetic oils include α-olefin oligomers such as polybutene, polyisobutylene, 1-octene oligomer, 1-decene oligomer, and ethylene-propylene copolymer, or their hydrogenated products, alkylbenzene, and alkylnaphthalene. Examples of the ether synthetic oils include polyoxyalkylene glycol and polyphenyl ether.

[0066] The base oil may be one selected from the above mineral oil and synthetic oil, or a mixture of two or more mineral oils, two or more synthetic oils, or one or more of each of mineral oil and synthetic oil. In the present embodiment, from the viewpoint of obtaining an oil composition having a viscosity suitable as a cable gel even when the blending ratio of the hydrogenated block copolymer in the oil composition is small, mineral oil is preferable as the base oil, and at least one selected from paraffinic mineral oil and naphthenic mineral oil is more preferable. Further, from the viewpoint of improving thixotropy by making the polymer block (A) in the hydrogenated block copolymer difficult to be plasticized, paraffinic mineral oil is preferable.

[0067] Mineral oil and synthetic oil are classified into Group I, II, III, IV, and V in the base oil classification of the American Petroleum Institute. Among them, paraffinic mineral oils classified into Group II and Group III are preferable because they have less sulfur content and more saturated content, and paraffinic mineral oil classified into Group II is more preferable.

[0068] The base oil used in the oil composition of this embodiment contains paraffin and naphthene, and preferably has a mass ratio of paraffin to naphthene [paraffin / naphthene] of 10 / 90 to 90 / 10. When the mass ratio of paraffin to naphthene is within the above range, the polymer block (A) in the hydrogenated block copolymer is less likely to be plasticized. From the viewpoint of improving the thixotropy of the oil composition of this embodiment, the mass ratio of paraffin to naphthene [paraffin / naphthene] is preferably 20 / 80 to 90 / 10, more preferably 30 / 70 to 90 / 10, still more preferably 40 / 60 to 90 / 10, even more preferably 50 / 50 to 90 / 10, even more preferably 60 / 40 to 90 / 10, and particularly preferably 60 / 40 to 80 / 20.

[0069] The base oil used in the oil composition of this embodiment preferably has a viscosity index of 70 or more, more preferably 80 or more, still more preferably 90 or more, even more preferably 100 or more. Also, it is preferably 200 or less, more preferably 180 or less, still more preferably 160 or less, even more preferably 150 or less, even more preferably 140 or less, particularly preferably 135 or less, and especially preferably less than 120.

Examples

[0070] Hereinafter, specific examples and comparative examples will be given to explain this embodiment in more detail, but the present invention is not limited in any way by the following examples and comparative examples. In the following examples and comparative examples, the physical properties of the hydrogenated block copolymer were measured and the characteristics were evaluated by the following methods.

[0071] 〔Measurement method of physical properties〕 (Content of vinyl aromatic monomer unit, 1,2-vinyl bond amount, hydrogenation rate) The content of vinyl aromatic monomer units in the hydrogenated block copolymer (hereinafter also referred to as styrene content), the amount of 1,2-vinyl bonds of conjugated diene monomer units in the block copolymer before hydrogenation, and the hydrogenation rate of double bonds based on conjugated diene monomer units were measured and determined by nuclear magnetic resonance spectrum analysis (NMR) under the following conditions. Here, the styrene content obtained is referred to as the "TS value". Measuring instrument: JNM-LA400 (manufactured by JEOL) Solvent: Deuterated chloroform Measurement sample: A sample taken before or after hydrogenating the polymer Sample concentration: 50 mg / mL Observation frequency: 400 MHz Chemical shift standard: TMS (tetramethylsilane) Pulse delay: 2.904 seconds Number of scans: 64 times Pulse width: 45° Measurement temperature: 26 °C

[0072] (Content of polymer block (A) in the hydrogenated block copolymer) The content of polymer block (A) in the hydrogenated block copolymer block was decomposed and measured by the osmium tetroxide acid method described in I.M. Kolthoff, et al., J. Polym. Sci. 1, 429 (1946) using the block copolymer before hydrogenation. Note that for the decomposition of the block copolymer, a 0.1 g / 125 mL tert-butanol solution of osmium acid was used.

[0073] (Content of polymer block (B) and content of vinyl aromatic monomer units in polymer block (B)) The content of polymer block (B) was calculated as the ratio of the mass of butadiene and styrene polymerized in a state where conjugated diene monomer units and vinyl aromatic monomer units coexisted to the mass of the total hydrogenated block copolymer. Also, the content of vinyl aromatic monomer units in polymer block (B) was calculated by the following formula. (Styrene content in polymer block (B)) / (Content of polymer block (B)) × 100

[0074] (Content of polymer block (C) and content of vinyl aromatic monomer units in polymer block (C)) The content of polymer block (C) was calculated as the proportion of only conjugated diene monomer units, or only butadiene polymerized in a state where conjugated diene monomer units and vinyl aromatic monomer units coexist, or the mass ratio of butadiene and styrene to the mass of the fully hydrogenated block copolymer. Also, the content of vinyl aromatic monomer units in polymer block (C) was calculated by the following formula. (Styrene content in polymer block (C)) / (Content of polymer block (C)) × 100

[0075] (Weight-average molecular weight of polymer block (A), weight-average molecular weight of the hydrogenated block copolymer) The weight-average molecular weight of polymer block (A) was measured by gel permeation chromatography (GPC) for the decomposition product of the osmium acid, and the weight-average molecular weight of the hydrogenated block copolymer was measured for the block copolymer after hydrogenation under the following conditions. The weight-average molecular weight of the hydrogenated block copolymer was determined from the PS (polystyrene) conversion calibration curve at the obtained peak. Measuring device: GPC; ACQUITY APC system (manufactured by Waters K.K., Japan) System (measurement / analysis) software; Empower3 Detector; RI Refractive index unit full scale; 500 μRIU Output full scale; 2000 mV Sampling rate; 10 points / sec Column; ACQUITY APC XT125 (4.6 mm × 150 mm); 1 piece ACQUITY APC XT200 (4.6 mm × 150 mm); 1 piece ACQUITY APC XT900 (4.6 mm × 150 mm); 1 piece ACQUITY APC XT450 (4.6 mm × 150 mm); 1 piece Solvent; THF Flow rate; 1.0 mL / min Concentration; 0.1 mg / mL Column temperature; 40 °C Injection volume; 20 μL

[0076] (Particle size) While checking the particle size of the hydrogenated block copolymer dissolved in oil by the following method, the particle size of the hydrogenated block copolymer was adjusted to 500 μm with a small grinder. Measuring device: Laser rotary particle size measuring device Mastersizer3000 (manufactured by Malvern) Wet method: Solvent DMF Spherical: Non-spherical Material: Rubber Refractive index: 1.525 Rotation speed: 2400 rpm

[0077] 〔Method for evaluating characteristics〕 (Evaluation of solubility in oil) To 100 parts by mass of the oil composition which is the base oil, 2 parts by mass of the hydrogenated block copolymer whose volume average particle size was adjusted to 500 μm by the method described in the above (particle size distribution) was added. Using a Three One Motor manufactured by Shin-Toyo Chemical Co., Ltd., a cross-shaped stirring blade was used, and stirring was carried out at a rotation speed of 800 rpm in an atmosphere of 160 °C, and the time until complete dissolution was measured and evaluated according to the following criteria. As the base oil used for the evaluation, "Diana Process Oil PW-90" (paraffin / naphthene mass ratio = 72 / 28, viscosity index: 107) manufactured by Idemitsu Kosan Co., Ltd. was used.

[0078] The solubility was evaluated according to the following criteria. 〇: The time required for dissolution is less than 1.5 hours. △: The time required for dissolution is 1.5 hours to less than 3 hours. ▽: The time required for dissolution is 3 hours or more and less than 4 hours. ×: The time required for dissolution is 4 hours or more, or undissolved matter was observed even after stirring for 5 hours. The solubility in oil was evaluated as 〇 being excellent and △ being good in practical use.

[0079] (Thixotropy evaluation) To 100 parts by mass of the oil composition as the base oil, 8 parts by mass of the hydrogenated block copolymer having a volume average particle diameter adjusted to 500 μm by the method described above was added. Using a Three One Motor manufactured by Shin-Toyo Chemical Co., Ltd., a cross-shaped stirring blade was used, and the mixture was stirred at 1300 rpm for 4 hours in an atmosphere of 180 °C to obtain an oil composition. To confirm the properties of the obtained oil composition, in the same manner as when preparing the oil composition, a Three One Motor was used, a cross-shaped stirring blade was used, and the behavior of the oil composition was confirmed at 800 rpm in an atmosphere of 23 °C. The fluidity of the oil composition when left standing at 100 °C for 5 days was confirmed and evaluated according to the following criteria.

[0080] The evaluation criteria for thixotropy are shown below. ◎: The contact part of the stirring blade is liquefied, no stringing is observed when taking out the stirring blade, and there is no deformation during standing. 〇: The contact part of the stirring blade is liquefied, slight stringing is observed when taking out the stirring blade, and there is no deformation during standing △: The contact part of the stirring blade is liquefied, no stringing is observed when taking out the stirring blade, and slight deformation is observed during standing. ▽: The contact part of the stirring blade is liquefied, no stringing is observed when taking out the stirring blade, and large deformation is observed during standing. ▽-: The contact part of the stirring blade is not liquefied, and the phenomenon that the whole composition winds up on the stirring rod is observed. ×: It becomes a rubbery lump at 23 °C and cannot be stirred. Therefore, it is judged that confirmation of fluidity is not necessary. Thixotropy was evaluated as particularly excellent for ◎, excellent for 〇, and practically good for △.

[0081] 〔Preparation of hydrogenated block copolymer〕 (Preparation of hydrogenation catalyst) In the examples and comparative examples described below, the hydrogenation catalyst used for preparing the hydrogenated block copolymer was prepared by the following method. A reaction vessel equipped with a stirring device was purged with nitrogen, and 1 L of dried and purified cyclohexane was charged therein. Next, 100 mmol of bis(η5-cyclopentadienyl)titanium dichloride was added. While stirring this thoroughly, an N-hexane solution containing 200 mmol of trimethylaluminum was added, and the reaction was carried out at room temperature for about 3 days. Thereby, a hydrogenation catalyst was obtained.

[0082] 〔Examples 1 to 13〕, 〔Comparative Examples 1 to 7〕 <Hydrogenated block copolymer 1> Using a stirring device with an internal volume of 100 L and a jacketed tank reactor, batch polymerization was carried out in the following manner. First, 36 L of cyclohexane was charged into the reactor, and after adjusting the temperature to 55 °C, 0.052 part by mass of n-butyllithium (hereinafter also referred to as "Bu-Li") and 0.9 mol of N,N,N',N'-tetramethylethylenediamine (hereinafter also referred to as "TMEDA") per 1 mol of Bu-Li were added to 100 parts by mass of the total amount of butadiene monomer and styrene monomer (hereinafter referred to as "total monomers") charged into the reactor. As the first step, 30.0 parts by mass of styrene was charged over 6 minutes and then reacted for an additional 15 minutes (reaching 65 °C by the polymerization reaction). At this point, the polymer solution was sampled, and when the polymerization conversion rate of styrene was measured, it was 100%. Next, as the second step, a cyclohexane solution (concentration 40 parts by mass) containing 5.0 parts by mass of styrene and 10.0 parts by mass of butadiene was continuously charged into the reactor at a constant rate over 20 minutes and then reacted for an additional 10 minutes (reaching 70 °C by the polymerization reaction). At this point, the polymer solution was sampled, and when the polymerization conversion rate of styrene and butadiene was measured, it was 100%. Next, as the third step, a cyclohexane solution (concentration 40 parts by mass) containing 55 parts by mass of butadiene was charged over 30 minutes and then reacted for an additional 10 minutes (reaching 85 °C by the polymerization reaction). At this point, the polymer solution was sampled, and when the polymerization conversion rate of butadiene was measured, it was 100%. Next, as the fourth step, 0.9 mol of methanol was added per 1 mol of Bu-Li to terminate the polymerization reaction, and a block copolymer was obtained. Next, to the obtained block copolymer, the hydrogenation catalyst was added at 100 ppm as titanium per 100 parts by mass of the block copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.9 MPa and a temperature of 90 °C for 2 hours. Thereafter, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was added as a stabilizer at 0.3 parts by mass per 100 parts by mass of the block copolymer to obtain a hydrogenated block copolymer 1.

[0083] <Hydrogenated block copolymers 2, 3, 19> Hydrogenated block copolymers 2, 3, 19 were obtained in the same manner as in Example 1 except that the addition amount of TMEDA was adjusted.

[0084] <Hydrogenated block copolymers 4, 5> Hydrogenated block copolymers 4, 5 were obtained in the same manner as in Example 1 except that the addition amount of Bu-Li was adjusted.

[0085] <Hydrogenated block copolymer 6> A hydrogenated block copolymer 6 was obtained in the same manner as in Example 1 except that the amount of styrene was adjusted in the first step, the amounts of styrene and butadiene were adjusted in the second step, and the amount of butadiene was adjusted in the third step.

[0086] <Hydrogenated block copolymer 7> A hydrogenated block copolymer 7 was obtained in the same manner as in Example 1 except that the amount of styrene was adjusted in the first step and the amount of butadiene was adjusted in the second step.

[0087] <Hydrogenated block copolymer 8> A block copolymer 8 was obtained in the same manner as in Example 1 except that the hydrogenation reaction time was adjusted in the fourth step.

[0088] <Hydrogenated block copolymers 9, 20> Except that the amount of styrene was adjusted in the first step and the amounts of styrene and butadiene were adjusted in the second step, hydrogenated block copolymers 9 and 20 were obtained in the same manner as in Example 1.

[0089] <Hydrogenated block copolymer 10> Except that the amount of butadiene was adjusted in the second step, the third step was not carried out, and the fourth step was carried out after the second step, hydrogenated block copolymer 10 was obtained in the same manner as in Example 1.

[0090] <Hydrogenated block copolymers 11, 12, 13> Except that the amount of styrene was adjusted in the first step, the amounts of styrene and butadiene were adjusted in the second step, and styrene with its amount adjusted was added together with butadiene with its amount adjusted in the third step, hydrogenated block copolymers 11, 12, and 13 were obtained in the same manner as in Example 1.

[0091] <Hydrogenated block copolymer 14> Except that the amounts of TMEDA and Bu-Li added were adjusted, the amount of styrene was adjusted in the first step, the amounts of styrene and butadiene were adjusted in the second step, the third step was not carried out, and the fourth step was carried out after the second step, hydrogenated block copolymer 14 was obtained in the same manner as in Example 1.

[0092] <Hydrogenated block copolymer 15> Except that the amounts of TMEDA and Bu-Li added were adjusted, the amount of styrene was adjusted in the first step, the amounts of styrene and butadiene were adjusted in the second step, and styrene with its amount adjusted was added instead of butadiene in the third step, hydrogenated block copolymer 15 was obtained in the same manner as in Example 1.

[0093] <Hydrogenated block copolymer 16> Except that the amounts of TMEDA and Bu-Li added were adjusted, the amount of styrene was adjusted in the first step, the second step was not carried out, and butadiene with its amount adjusted was added in the third step after the first step, hydrogenated block copolymer 16 was obtained in the same manner as in Example 1.

[0094] <Hydrogenated block copolymer 17> The amount of TMEDA and the amount of Bu-Li added were adjusted. The amount of styrene was adjusted in the first step, and the second step was not carried out. After the first step was carried out, in the third step, instead of butadiene, isoprene with the adjusted amount was added. Otherwise, in the same manner as in Example 1, hydrogenated block copolymer 17 was obtained.

[0095] <Hydrogenated block copolymer 18> In the second step, the amounts of styrene and butadiene were adjusted, and in the third step, the amount of butadiene was adjusted. Otherwise, in the same manner as in Example 1, hydrogenated block copolymer 18 was obtained.

[0096] The hydrogenated block copolymers 1 to 20 obtained as described above were evaluated by the above method. The physical properties and evaluation results of each hydrogenated block copolymer are shown in Tables 1 to 2 below.

[0097]

Table 1

[0098]

Table 2

[0099] According to the examples of the present invention, a hydrogenated block copolymer having excellent solubility in base oil, good thixotropy (good fluidity under shear stress and gel-like properties at rest), and an excellent performance balance in practical use was obtained.

Industrial Applicability

[0100] In addition to the viscosity index improver and cable filling material described above, the hydrogenated block copolymer of the present invention can be used, for example, in cosmetic compositions constituting cosmetic products. Examples of cosmetic products include hair makeup products such as shampoos, hair setting gels or lotions, blow-drying lotions, fixing and styling agents; skin makeup products such as foundations, eyeshadows, blushes, concealers, compact powders, and makeup bases; lip makeup products such as lipsticks, liquid lips, and lip glosses; cleansing products such as facial cleansing foams and makeup removers; and cream products such as petrolatum creams, hand creams, and creams for ultrasonic diagnosis. Furthermore, the oil composition of the present invention has industrial applicability as a material for asphalt modifiers, adhesives, tackifiers, resin modifiers, compatibilizers, sealing materials, coating materials, molded products, fibers and non-woven fabrics, viscosity index improvers, and oil adsorbents.

Claims

1. One polymer block (A) mainly composed of vinyl aromatic monomer units with a molecular weight of 7000 or more, and at least one polymer block (B) containing conjugated diene monomer units and vinyl aromatic monomer units, which is a hydrogenated block copolymer having the content of vinyl aromatic monomer units in the hydrogenated block copolymer is 5.0% by mass or more and 37.5% by mass or less, the vinyl aromatic monomer units in the polymer block (B) are 1.0% by mass or more and 45.0% by mass or less, the amount of 1,2 - vinyl bonds in the conjugated diene monomer units is 50.0 mol% or more and 80 mol% or less, a hydrogenated block copolymer.

2. The hydrogenation rate of the conjugated diene monomer units is 60.0 mol% or more and 100 mol% or less, The hydrogenated block copolymer according to Claim 1.

3. The conjugated diene monomer units are derived from butadiene, The hydrogenated block copolymer according to Claim 1.

4. The weight - average molecular weight is 20,000 to 500,000, The hydrogenated block copolymer according to Claim 1.

5. Further having a polymer block (C) with a higher proportion of conjugated diene monomers than the polymer block (B), The hydrogenated block copolymer according to Claim 1.

6. A viscosity index improver containing the hydrogenated block copolymer according to any one of Claims 1 to 5.

7. The hydrogenated block copolymer according to any one of Claims 1 to 5, and a base oil, which contains the content of the hydrogenated block copolymer is 0.1% by mass or more and 40.0% by mass or less, an oil composition.

8. The base oil is mineral oil and / or synthetic oil, the oil composition according to Claim 7.

9. The oil composition according to Claim 7 is a cable gel.

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