JPWO2014142001A1 - Viscosity index improver, method for producing the same, and oil composition - Google Patents

Abstract

The present invention provides a viscosity index improver that is excellent in the effect of improving the viscosity index of oil and the high-temperature high-shear viscosity. The viscosity index improver of the present invention is a viscosity index improver comprising a hydrogenated product of a copolymer containing a structural unit (a) derived from an aromatic vinyl compound and a structural unit (b) derived from a conjugated diene, In the total amount of structural unit (b) derived from conjugated diene, the content of structural unit (b1) derived from farnesene is 1 to 100% by mass, and the content of structural unit (b2) derived from conjugated diene other than farnesene is The viscosity index improver is 0 to 99% by mass, and the carbon-carbon double bond in the structural unit (b) derived from the conjugated diene is hydrogenated by 50 mol% or more.

Description

  The present invention relates to a viscosity index improver comprising a hydrogenated product of a copolymer containing a structural unit derived from farnesene, a method for producing the same, and an oil composition comprising the viscosity index improver and a base oil.

A hydrogenated block copolymer composed of a polymer block composed of a structural unit derived from an aromatic vinyl compound and a polymer block composed of a structural unit derived from a conjugated diene is a vulcanized rubber without further vulcanization. It exhibits the same characteristics and is excellent in vibration damping, flexibility, rubber elasticity, and weather resistance, so it is widely used in daily goods, automotive parts, various industrial products, etc.
Such a hydrogenated block copolymer is obtained, for example, by hydrogenating a block copolymer obtained by sequentially polymerizing an aromatic vinyl compound and a conjugated diene such as isoprene or butadiene (for example, (See Patent Documents 1 and 2).
In addition, a hydrogenated block copolymer composed of a polymer block composed of a structural unit derived from an aromatic vinyl compound and a polymer block composed of a structural unit derived from a conjugated diene has a viscosity for lubricating oil. Patent Document 3 describes use as an index improver.
Although Patent Documents 4 and 5 describe polymers of β-farnesene, practical properties have not been sufficiently studied.

Japanese Patent No. 2777239 JP 2010-090267 A Special table 2009-532513 Special table 2012-502135 gazette Special table 2012-502136 gazette

The viscosity index improver disclosed in Patent Document 3 is excellent in the effect of improving the viscosity index and high-temperature high-shear viscosity of a lubricating oil, but development of different types of viscosity index improvers that are excellent in the effect is desired. .
The subject of this invention is providing the viscosity index improver excellent in the improvement effect of the viscosity index of oil and high temperature high shear viscosity, its manufacturing method, and an oil composition with high viscosity index and high temperature high shear viscosity.

The present invention relates to the following [1] to [3].
[1] A viscosity index improver comprising a hydrogenated product of a copolymer containing a structural unit (a) derived from an aromatic vinyl compound and a structural unit (b) derived from a conjugated diene, the structural unit derived from the conjugated diene In the total amount of (b), the content of the structural unit (b1) derived from farnesene is 1 to 100% by mass, and the content of the structural unit (b2) derived from a conjugated diene other than farnesene is 0 to 99% by mass. Yes, a viscosity index improver in which the carbon-carbon double bond in the structural unit (b) derived from the conjugated diene is hydrogenated by 50 mol% or more.
[2] An oil composition comprising a base oil and the viscosity index improver of [1] above.
[3] A polymerization step of obtaining a copolymer containing the structural unit (a) derived from the aromatic vinyl compound and the structural unit (b) derived from the conjugated diene by anionic polymerization, and the structural unit (b) derived from the conjugated diene The method for producing a viscosity index improver according to the above [1], comprising a step of hydrogenating a carbon-carbon double bond by 50 mol% or more.

  ADVANTAGE OF THE INVENTION According to this invention, the viscosity index improver excellent in the improvement effect of the viscosity index of oil and high temperature high shear viscosity, its manufacturing method, and an oil composition with a high viscosity index and high temperature high shear viscosity can be provided.

[Viscosity index improver]
The viscosity index improver of the present invention may be abbreviated as a copolymer containing a structural unit (a) derived from an aromatic vinyl compound and a structural unit (b) derived from a conjugated diene (hereinafter referred to as “copolymer”). ) In the total amount of the structural unit (b) derived from the conjugated diene, which is derived from farnesene. The content of the structural unit (b1) is 1 to 100% by mass, the content of the structural unit (b2) derived from a conjugated diene other than farnesene is 0 to 99% by mass, and the structural unit derived from the conjugated diene ( It is a viscosity index improver in which the carbon-carbon double bond in b) is hydrogenated by 50 mol% or more.

The hydrogenated copolymer constituting the viscosity index improver of the present invention may be either a hydrogenated product of a block copolymer or a hydrogenated product of a random copolymer.
That is, the viscosity index improver of the present invention comprises a polymer block (A) mainly composed of the structural unit (a) derived from the aromatic vinyl compound and a heavy polymer composed mainly of the structural unit (b) derived from the conjugated diene. It may consist of a hydrogenated block copolymer containing the combined block (B) (hereinafter sometimes abbreviated as “hydrogenated block copolymer”).
The viscosity index improver of the present invention is such that the structural unit (a) derived from the aromatic vinyl compound, the structural unit (b1) derived from the farnesene, and the structural unit (b2) derived from a conjugated diene other than the farnesene are randomly selected. It may consist of a hydrogenated product of a random copolymer obtained by polymerization (hereinafter sometimes abbreviated as “hydrogenated random copolymer”).

<Aromatic vinyl compound-derived structural unit (a)>
Said copolymer contains the structural unit (a) derived from an aromatic vinyl compound. Examples of the aromatic vinyl compound include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 4-t-butylstyrene, 4-cyclohexylstyrene, 4- Dodecylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 2,4,6-trimethylstyrene, 2-ethyl-4-benzylstyrene, 4- (phenylbutyl) styrene, 1-vinylnaphthalene, 2- Examples include vinyl naphthalene, vinyl anthracene, N, N-diethyl-4-aminoethyl styrene, vinyl pyridine, 4-methoxy styrene, monochlorostyrene, dichlorostyrene and divinylbenzene. These aromatic vinyl compounds may be used alone or in combination of two or more. Among these, from the viewpoint of improving the viscosity index and high-temperature high shear viscosity of oil, styrene, α-methylstyrene, and 4-methylstyrene are more preferable, and styrene is still more preferable.
In the present invention, a compound having both an aromatic group and a conjugated diene bond in one molecule is not included in the conjugated diene that is a component derived from the structural unit (b), but is a component derived from the structural unit (a). Included in certain aromatic vinyl compounds. However, the content of the structural unit derived from the compound having both an aromatic group and a conjugated diene bond in one molecule in the structural unit (a) is preferably 10% by mass or less, more preferably 5% by mass. Hereinafter, it is more preferably 1% by mass or less.

<Structural unit derived from conjugated diene (b)>
Said copolymer contains the structural unit (b) derived from a conjugated diene. Although this copolymer contains the structural unit (b1) derived from farnesene as the structural unit (b), it may further contain a structural unit (b2) derived from a conjugated diene other than farnesene.
The content of the structural unit (b1) derived from farnesene in the total amount of the structural unit (b) derived from this conjugated diene is 1 to 100% by mass, preferably 40 to 100% by mass, more preferably 50 to 100% by mass. Furthermore, it is more preferably 55 to 100% by mass, still more preferably 60 to 100% by mass, still more preferably 90 to 100% by mass, and still more preferably 95 to 100% by mass.
In the total amount of the structural unit (b) derived from the conjugated diene, the content of the structural unit (b2) derived from the conjugated diene other than farnesene is 0 to 99% by mass, preferably 0 to 60% by mass. Preferably it is 0-50 mass%, More preferably, it is 0-10 mass%, More preferably, it is 0-5 mass%.
Farnesene can be industrially produced using microorganisms from sugar extracted from plants such as sugarcane. And since the viscosity index improver of this invention is obtained from such farnesene as a raw material, it can be manufactured with little environmental load.

(Structural unit derived from farnesene (b1))
The farnesene which is a component derived from the structural unit (b1) may be either α-farnesene or β-farnesene represented by the following formula (I), or both may be used in combination.
The content of the structural unit derived from β-farnesene in the structural unit (b1) is preferably 60% by mass or more from the viewpoint of improving the ease of production of the copolymer and the viscosity index and high-temperature high-shear viscosity of the oil. More preferably, it is 80 mass% or more, More preferably, it is 90 mass% or more, More preferably, it is 99 mass% or more, More preferably, it is 100 mass%.

(Structural unit derived from conjugated dienes other than farnesene (b2))
The copolymer may contain a structural unit (b2) derived from a conjugated diene other than farnesene. Examples of conjugated dienes other than farnesene, which is a component derived from the structural unit (b2), include butadiene, isoprene, 2,3-dimethyl-butadiene, 2-phenyl-butadiene, 1,3-pentadiene, and 2-methyl-1,3. -Pentadiene, 1,3-hexadiene, 1,3-octadiene, 1,3-cyclohexadiene, 2-methyl-1,3-octadiene, 1,3,7-octatriene, myrcene and chloroprene. These may be used alone or in combination of two or more. Among these, at least one of butadiene, isoprene and myrcene is more preferable, and at least one of butadiene and isoprene is more preferable.

<Other structural unit (c)>
The copolymer may contain other structural units (c) in addition to the structural units (a), (b1) and (b2).
Examples of the component derived from the structural unit (c) include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-undecene, 1-undecene, Unsaturated hydrocarbon compounds such as dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene; acrylic acid, methacrylic acid, methyl acrylate , Methyl methacrylate, acrylonitrile, methacrylonitrile, maleic acid, fumaric acid, crotonic acid, itaconic acid, 2-acryloylethanesulfonic acid, 2-methacryloylethanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2- Methacrylamide-2-methylpropanesulfonic acid, vinyl Functional group-containing unsaturated compounds such as sulfonic acid, vinyl acetate, and methyl vinyl ether; These may be used alone or in combination of two or more.

<Copolymer>
The copolymer in the present invention includes a structural unit (a) derived from the aromatic vinyl compound and a structural unit (b) derived from the conjugated diene. In addition, the said copolymer may contain the said structural unit (c) further.
In the copolymer, the total content of the structural unit (a) and the structural unit (b) is preferably 60% by mass or more, more preferably from the viewpoint of improving the viscosity index and high-temperature high-shear viscosity of the oil. It is 80 mass% or more, More preferably, it is 90 mass% or more, More preferably, it is 99 mass% or more.
From the same viewpoint, the content of the structural unit (c) in the total amount of the structural units constituting the copolymer is preferably 40% by mass or less, more preferably 20% by mass or less, and still more preferably. It is 10 mass% or less, More preferably, it is 1 mass% or less.
The content of the structural unit (a) in the copolymer is preferably 1 to 99% by mass, more preferably 2 to 90% by mass, and still more preferably, from the viewpoint of improving the viscosity index and high-temperature high shear viscosity of the oil. Is 3 to 85% by mass, more preferably 5 to 80% by mass, still more preferably 10 to 50% by mass, and still more preferably 15 to 45% by mass.
The mass ratio [(a) / (b)] of the total amount of the structural unit (a) and the total amount of the structural unit (b) is preferably 1/99 from the viewpoint of improving the viscosity index and the high temperature high shear viscosity of the oil. To 99/1, more preferably 2/98 to 90/10, still more preferably 3/97 to 85/15, still more preferably 5/95 to 80/20, and even more preferably 10/90 to 50/50. More preferably, it is 15/85 to 45/55.
The copolymer in the present invention may be either a block copolymer or a random copolymer. Next, these two types of copolymers will be described.

(Block copolymer)
The copolymer in the present invention comprises a polymer block (A) mainly composed of the structural unit (a) derived from the aromatic vinyl compound and a polymer block mainly composed of the structural unit (b) derived from the conjugated diene ( And a block copolymer containing B).
As used herein, “mainly” means that the polymer block (A) contains 50% by mass or more of the structural unit (a) derived from the aromatic vinyl compound based on the total mass of the polymer block (A). What contains 70 mass% or more of the structural unit (a) derived from the aromatic vinyl compound is preferable, and what contains 90 mass% or more is more preferable. Similarly, the polymer block (B) is said to contain 50% by mass or more of the structural unit (b) derived from the conjugated diene based on the total mass of the polymer block (B), and the structure derived from the conjugated diene. What contains 65 mass% or more of units (b) is preferable, and what contains 80 mass% or more is more preferable.

  The polymer block (B) preferably contains 1 to 100% by mass of farnesene-derived structural units (b1) and 99 to 0% by mass of structural units (b2) derived from conjugated dienes other than farnesene. Here, preferred specific examples and content ratios of the structural units (b1) and (b2) are as described above.

Furthermore, the polymer block (b) may have a small amount of structural units derived from other copolymerizable monomers within the range not impairing the object of the present invention. Examples of such other copolymerizable monomers include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 1,3-dimethylstyrene, diphenylethylene, 1-vinylnaphthalene. Copolymerizable monomers such as aromatic vinyl compounds such as 4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4- (phenylbutyl) styrene Is mentioned. These other copolymerizable monomers may be used individually by 1 type, and may use 2 or more types together. In the case of having structural units derived from the other copolymerizable monomers described above, the bonding form thereof may be either random or tapered.
When the polymer block (b) contains a structural unit derived from the other copolymerizable monomer, the content is preferably 35% by mass or less, more preferably 10% by mass or less, and more preferably 5% by mass or less. Is more preferable.

The bonding form of the polymer block (A) and the polymer block (B) is not particularly limited, and may be linear, branched, radial, or a combination of two or more thereof. Among them, when the polymer block (A) is represented by A and the polymer block (B) is represented by B from the viewpoint of improving the viscosity index and high temperature high shear viscosity of the oil, (AB) _l , A- (B -A) _m , B- (AB) _n (l, m, n are each independently an integer of 1 or more), each block is linearly coupled, and (A- B) _p X, ( _BA ) _q X (p and q are each independently an integer of 3 or more, X is a coupling agent residue), each block is bound radially. The form is preferred.
As the bonding form, a diblock copolymer represented by A-B or a triblock represented by A-B-A is preferable from the viewpoint of improving the viscosity index and high-temperature high-shear viscosity of oil.
When the block copolymer has two or more polymer blocks (A) or two or more polymer blocks (B), each polymer block is a polymer block composed of the same structural unit. Alternatively, it may be a polymer block composed of different structural units. For example, in the two polymer blocks (A) in the triblock copolymer represented by [A-B-A], each aromatic vinyl compound may be the same or different in type. Good.

The peak top molecular weight of the polymer block (A) is preferably 10,000 or more and 60,000 or less, and preferably 15,000 or more and 50 or more from the viewpoint of the effect of improving the viscosity index of oil and the ease of production of the oil composition. Is more preferably 1,000 or less. If the peak top molecular weight of the polymer block (A) is less than 10,000, the effect of improving the viscosity index of the oil may be reduced. On the other hand, if it is larger than 60,000, the solubility of the resulting block copolymer in the oil will be lowered, and the effect of improving the viscosity index of the oil may not be obtained. When the block copolymer has two or more polymer blocks (A), it is preferable that the peak top molecular weight of at least one of the polymer blocks is within the above range.
The block copolymer includes at least one polymer block selected from the polymer blocks (A) and (A ′) mainly composed of the structural unit (a) derived from the aromatic vinyl compound, and the conjugated diene. A polymer block mainly comprising the derived structural unit (b) and (B), the bond form of which is AB or ABA ′, and the peak top of the polymer block (A ′) A block copolymer having a molecular weight of 1,000 or more and less than 10,000 is even more preferable. The peak top molecular weight of the polymer block (A ′) is particularly preferably from 1,000 to 8,000. When the peak top molecular weight of the polymer block (A ′) is less than 10,000, the hydrogenated block copolymer is prevented from forming a gel network in the oil composition, and thus the obtained oil composition The increase in kinematic viscosity at 40 ° C. and 100 ° C. is suppressed, and use as a lubricating oil is easy.
The peak top molecular weights of the polymer blocks (A) and (A ′) are determined by sampling a part of the reaction solution during the synthesis of the block copolymer and measuring it by the method described in the examples described later. .

(Random copolymer)
In the copolymer of the present invention, the structural unit (a) derived from the aromatic vinyl compound, the structural unit (b1) derived from the farnesene, and the structural unit (b2) derived from a conjugated diene other than the farnesene are randomly polymerized. It may be a random copolymer.

<Hydrogenated copolymer>
The hydrogenated copolymer constituting the viscosity index improver of the present invention is obtained by hydrogenating the above copolymer, and the carbon-carbon double bond in the structural unit (b) derived from the conjugated diene is 50 mol. % Or more hydrogenated, that is, the hydrogenation rate is 50 mol% or more.
Here, the hydrogenation rate is the number of moles of conjugated diene-derived double bonds contained per mole of copolymer, M1, and the mole of conjugated diene-derived double bonds contained per mole of hydrogenated copolymer. When the number is M2, it is a value represented by the following formula.
Hydrogenation rate = (1-M2 / M1) × 100 (mol%)
This hydrogenation rate is preferably 60 mol% or more, more preferably 70 mol% or more, from the viewpoint of improving the heat resistance and shear stability of the oil, the viscosity index and the high temperature and high shear viscosity. In addition, this hydrogenation rate can be calculated | required by the method described in the Example mentioned later.

The peak top molecular weight (Mp) of the hydrogenated copolymer is preferably from 4,000 to 1,500,000, and preferably from 9,000 to 1,200,000 from the viewpoint of ease of production of the oil composition and the viscosity index of the oil. 000 is more preferable, 20,000 to 1,100,000 is more preferable, and 100,000 to 800,000 is most preferable.
In addition, the peak top molecular weight (Mp) in this specification means the value measured by the method described in the Example mentioned later.

  1-4 is preferable, as for the molecular weight distribution (Mw / Mn) of a hydrogenated copolymer, 1-3 are more preferable, and 1-2 are still more preferable. When the molecular weight distribution is within the above range, the viscosity variation of the hydrogenated block copolymer is small.

[Method for producing hydrogenated copolymer]
The hydrogenated copolymer includes a polymerization step for obtaining a copolymer containing a structural unit (a) derived from an aromatic vinyl compound and a structural unit (b) derived from a conjugated diene by anionic polymerization, and a structural unit derived from the conjugated diene ( It can manufacture suitably by passing through the process of hydrogenating the carbon-carbon double bond in b) 50 mol% or more. About a hydrogenation process, it can carry out by the method similar to the hydrogenation process of the hydrogenated block copolymer mentioned later.
Next, the manufacturing method of a hydrogenated block copolymer is demonstrated in detail.

[Method for producing hydrogenated block copolymer]
The hydrogenated block copolymer comprises a polymer block (A) mainly composed of the structural unit (a) derived from the aromatic vinyl compound and a polymer block (B) composed mainly of the structural unit (b) derived from the conjugated diene. And a step of hydrogenating the carbon-carbon double bond in the structural unit (b) derived from the conjugated diene in an amount of 50 mol% or more. Can be manufactured.

<Polymerization process>
The block copolymer can be produced by a solution polymerization method or a method described in JP-A-2012-502135 and JP-A-2012-502136. Among them, the solution polymerization method is preferable, and known methods such as an ion polymerization method such as anion polymerization and cation polymerization, and a radical polymerization method can be applied. Among these, the anionic polymerization method is preferable. As the anionic polymerization method, an aromatic vinyl compound, farnesene and / or conjugated dienes other than farnesene are sequentially added in the presence of a solvent, an anionic polymerization initiator, and, if necessary, a Lewis base to obtain a block copolymer. It is preferable.
Examples of the anionic polymerization initiator include alkali metals such as lithium, sodium and potassium; alkaline earth metals such as beryllium, magnesium, calcium, strontium and barium; lanthanoid rare earth metals such as lanthanum and neodymium; And compounds containing earth metals and lanthanoid rare earth metals. Of these, alkali metals, compounds containing alkali metals, and organic alkali metal compounds are preferred.

Examples of such an organic alkali metal compound include methyl lithium, ethyl lithium, n-butyl lithium, sec-butyl lithium, t-butyl lithium, hexyl lithium, phenyl lithium, stilbene lithium, dilithiomethane, dilithionaphthalene, and 1,4. -Organic lithium compounds such as dilithiobutane, 1,4-dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene; sodium naphthalene, potassium naphthalene and the like. Among these, an organic lithium compound is preferable, n-butyl lithium and sec-butyl lithium are more preferable, and sec-butyl lithium is particularly preferable. The organic alkali metal compound may be used as an organic alkali metal amide by reacting with a secondary amine such as diisopropylamine, dibutylamine, dihexylamine, and dibenzylamine.
The amount of the organic alkali metal compound used for the polymerization varies depending on the molecular weight of the block copolymer, but usually 0.01 to 3 mass relative to the total amount of the aromatic vinyl compound and farnesene and / or conjugated diene other than farnesene. % Range.

  The solvent is not particularly limited as long as it does not adversely affect the anionic polymerization reaction. For example, saturated aliphatic hydrocarbons such as n-pentane, isopentane, n-hexane, n-heptane, and isooctane; cyclopentane, cyclohexane, methylcyclo Saturated alicyclic hydrocarbons such as pentane; aromatic hydrocarbons such as benzene, toluene, xylene and the like. These may be used alone or in combination of two or more. There is no restriction | limiting in particular in the usage-amount of a solvent.

  The Lewis base has a role of controlling the microstructure in the structural unit (b1) derived from farnesene and the structural unit (b2) derived from conjugated dienes other than farnesene. Examples of the Lewis base include ether compounds such as dibutyl ether, diethyl ether, tetrahydrofuran, dioxane, and ethylene glycol diethyl ether; pyridine; tertiary amines such as N, N, N ′, N′-tetramethylethylenediamine and trimethylamine; Examples include alkali metal alkoxides such as potassium t-butoxide; phosphine compounds. When a Lewis base is used, the amount thereof is preferably in the range of 0.01 to 1000 mol equivalent to 1 mol of the anionic polymerization initiator.

The temperature of the polymerization reaction is usually in the range of −80 to 150 ° C., preferably 0 to 100 ° C., more preferably 10 to 90 ° C. The polymerization reaction may be carried out batchwise or continuously. Each monomer is continuously or intermittently supplied into the polymerization reaction solution so that the amount of aromatic vinyl compound, farnesene and / or conjugated diene other than farnesene in the polymerization reaction system falls within a specific range, Moreover, a block copolymer can be manufactured by superposing | polymerizing sequentially so that each monomer may become a specific ratio in a polymerization reaction liquid.
The polymerization reaction can be stopped by adding an alcohol such as methanol or isopropanol as a polymerization terminator. The block copolymer can be isolated by pouring the obtained polymerization reaction liquid into a poor solvent such as methanol to precipitate the block copolymer, or washing the polymerization reaction liquid with water, separating, and drying.

{Modified copolymer}
In the main polymerization step, an unmodified block copolymer may be obtained as described above, or a block copolymer modified as described below may be obtained.
The block copolymer may be modified before the hydrogenation step described later. Examples of functional groups that can be introduced include amino groups, alkoxysilyl groups, hydroxyl groups, epoxy groups, carboxyl groups, carbonyl groups, mercapto groups, isocyanate groups, and acid anhydrides.
Examples of the modification method of the block copolymer include, for example, tin tetrachloride, tetrachlorosilane, dimethyldichlorosilane, dimethyldiethoxysilane, tetramethoxysilane, tetraethoxy which can react with the polymerization active terminal before adding a polymerization terminator. Coupling agents such as silane, 3-aminopropyltriethoxysilane, tetraglycidyl-1,3-bisaminomethylcyclohexane, 2,4-tolylene diisocyanate, 4,4′-bis (diethylamino) benzophenone, N-vinyl Examples thereof include a method of adding a polymerization terminal modifier such as pyrrolidone or other modifiers described in JP2011-132298A. In addition, maleic anhydride or the like can be grafted onto the isolated copolymer.
The position at which the functional group is introduced may be a polymerization terminal of the block copolymer or a side chain. Moreover, the said functional group may combine 1 type (s) or 2 or more types. The modifying agent is preferably in the range of usually 0.01 to 10 molar equivalents relative to the anionic polymerization initiator.

<Hydrogenation process>
A hydrogenated block copolymer can be obtained by subjecting the block copolymer obtained by the above method to a hydrogenation step. A known method can be used for the hydrogenation. For example, a Ziegler catalyst in a solution in which a block copolymer is dissolved in a solvent that does not affect the hydrogenation reaction; nickel, platinum, palladium, ruthenium, rhodium metal catalyst supported on carbon, silica, diatomaceous earth, etc. A hydrogenation reaction is carried out in the presence of an organometallic complex having cobalt, nickel, palladium, rhodium, ruthenium metal or the like as a hydrogenation catalyst. In the hydrogenation step, a hydrogenation catalyst may be added to the polymerization reaction solution containing the block copolymer obtained by the above-described block copolymer production method to perform a hydrogenation reaction. In the present invention, palladium carbon in which palladium is supported on carbon is preferable.
In the hydrogenation reaction, the hydrogen pressure is preferably 0.1 to 20 MPa, the reaction temperature is preferably 100 to 200 ° C., and the reaction time is preferably 1 to 20 hours.

  The hydrogenation rate of the carbon-carbon double bond in the polymer block (B) in the block copolymer is preferably from the viewpoint of improving the heat resistance and shear stability of the oil, the viscosity index, and the high temperature and high shear viscosity. Is 50 mol% or more, more preferably 60 mol% or more, still more preferably 70 mol% or more. The hydrogenation rate can be calculated by the method described in the examples described later.

[Oil composition]
The oil composition of the present invention contains a base oil and the aforementioned viscosity index improver.
This oil composition can be suitably used as engine oil, automatic transmission fluid, gear lubricating oil, and hydraulic oil.
The content of the viscosity index improver in this oil composition is preferably 0.05 to 10% by mass, more preferably 0.1 to 7% by mass, and still more preferably 0.2 to 5% by mass. And more preferably 0.5 to 5% by mass.

<Base oil>
Base oils include fuel oils such as middle distillate fuels, synthetic and natural lubricating oils, unrefined oils and industrial oils. The base oil may be at least one of paraffinic, naphthenic and aromatic. Further, the base oil may be at least one of natural oil or synthetically prepared oil.
<Other additives>
The oil composition of the present invention comprises a rust inhibitor, an antioxidant, a surfactant, a pour point depressant, a cleaning dispersant, a metal deactivator, an antifoaming agent, a friction modifier, an extreme pressure agent, one or Other additives such as further further viscosity index improvers may also be included.
<Method for producing oil composition>
The oil composition of the present invention can be produced using production methods well known in the art.
For example, the oil composition of the present invention can be produced by mixing the above base oil and the above viscosity index improver. Mixing can be performed using a known mixing apparatus.
The mixing is preferably performed while heating. The heating temperature is preferably 80 to 180 ° C.

When the oil composition of the present invention is used for engine oil, automatic transmission fluid, gear lubricating oil, hydraulic oil, etc., the kinematic viscosity at 40 ° C. is preferably in the range of 40 to 120 mm ² / sec, 50 to 70 mm. A range of ² / sec is preferred. From the same viewpoint, the kinematic viscosity at 100 ° C. is preferably in the range of 6~25mm ² / sec, and more preferably in a range of from 8 to 15 mm ² / sec. When it is within the range, the fuel consumption of the vehicle can be reduced when used in the above-mentioned applications.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples. Note that β-farnesene (purity 97.6% by mass Amyris Biotechnology) was purified by 3 molecular sieves and distilled under a nitrogen atmosphere, so that gingivalene, bisabolene, farnesene epoxide, farnesol isomer, E , E-farnesol, squalene, ergosterol and farnesene were used for the following polymerization, except for hydrocarbon impurities such as several dimers.

(1) Measurement of molecular weight distribution (Mw / Mn) and peak top molecular weight (Mp) Weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the hydrogenated block copolymer obtained in each Example and Comparative Example ) Was determined by GPC (gel permeation chromatography) in terms of standard polystyrene equivalent molecular weight. Further, the peak top molecular weight (Mp) was defined as the position of the peak of this molecular weight distribution (Mw / Mn). The measuring apparatus and conditions are as follows.
・ Device: GPC device “GPC8020” manufactured by Tosoh Corporation
Separation column: “TSKgel G4000HXL” manufactured by Tosoh Corporation
Detector: “RI-8020” manufactured by Tosoh Corporation
・ Eluent: Tetrahydrofuran ・ Eluent flow rate: 1.0 ml / min ・ Sample concentration: 5 mg / 10 ml
-Column temperature: 40 ° C

(2) Measuring method of hydrogenation rate In each example and comparative example, the block copolymer and the hydrogenated block copolymer after hydrogenation were dissolved in a deuterated chloroform solvent, respectively, and “Lambda-500” manufactured by JEOL Ltd. Was used to measure ¹ H-NMR at 50 ° C. The hydrogenation rate of the polymer block (B) in the hydrogenated block copolymer is determined by the following formula from the peak of the proton possessed by the carbon-carbon double bond appearing at 4.5 to 6.0 ppm in the obtained spectrum. Calculated.
Hydrogenation rate = {1− (number of moles of carbon-carbon double bond contained per mole of hydrogenated block copolymer) / (mol of carbon-carbon double bond contained per mole of block copolymer) Number)} × 100 (mol%)

(3) Kinematic viscosity Kinematic viscosity at 40 ° C and 100 ° C was measured according to JIS K2283.
(4) Viscosity index The viscosity index was measured according to JIS K2283.
(5) High temperature high shear viscosity High temperature high shear viscosity at 150 ° C was measured according to ASTM D4683.

[Example 1]
In a pressure vessel that was purged with nitrogen and dried, 62.4 kg of cyclohexane as a solvent and 51.0 g of sec-butyllithium (10.5 mass% cyclohexane solution) as an anionic polymerization initiator were charged and heated to 50 ° C., By adding 2.34 kg of styrene (1) and polymerizing for 1 hour, subsequently adding 10.9 kg of β-farnesene to perform polymerization for 2 hours, and further adding 2.34 kg of styrene (2) and polymerizing for 1 hour, A reaction solution containing a polystyrene-poly (β-farnesene) -polystyrene triblock copolymer was obtained. To this reaction solution, 5% by mass of palladium carbon (palladium supported amount: 5% by mass) as a hydrogenation catalyst was added to the block copolymer, and the reaction was performed for 10 hours under conditions of a hydrogen pressure of 2 MPa and 150 ° C. . After allowing to cool and release, palladium carbon is removed by filtration, the filtrate is concentrated, and further dried under vacuum to obtain a hydrogenated polystyrene-poly (β-farnesene) -polystyrene triblock copolymer (hereinafter, “ Hydrogenated block copolymer (A1) ”) was obtained. Table 1 shows the blending of various raw materials and the measurement results of various physical properties of the obtained hydrogenated block copolymer (A1).
The obtained hydrogenated block copolymer (A1) was used as a viscosity index improver, and paraffinic oil “Diana Fresia S-32” manufactured by Idemitsu Kosan Co., Ltd. was used as a base oil. The oil composition was obtained by blending the copolymer (A1) as shown in Table 2 and mixing for 6 hours at a heating temperature of 120 ° C. and a rotational speed of 350 rpm in a nitrogen-substituted pressure vessel. This oil composition was evaluated as described above. The results are shown in Table 2.

[Example 2]
In a pressure vessel that was purged with nitrogen and dried, 62.4 kg of cyclohexane as a solvent and 40.6 g of sec-butyllithium (10.5 mass% cyclohexane solution) as an anionic polymerization initiator were charged, and the temperature was raised to 50 ° C. 13.0 kg of β-farnesene was added for polymerization for 2 hours, and then 2.59 kg of styrene was added for polymerization for 1 hour to obtain a reaction solution containing poly (β-farnesene) -polystyrene diblock copolymer. It was. To this reaction solution, 5% by mass of palladium carbon (palladium supported amount: 5% by mass) as a hydrogenation catalyst was added to the block copolymer, and the reaction was performed for 10 hours under conditions of a hydrogen pressure of 2 MPa and 150 ° C. . After allowing to cool and release the pressure, palladium carbon is removed by filtration, the filtrate is concentrated, and further dried under vacuum to obtain a hydrogenated poly (β-farnesene) -polystyrene diblock copolymer (hereinafter “hydrogenated”). Block copolymer (A2) ”) was obtained. Table 1 shows the blending of various raw materials and the measurement results of various physical properties of the obtained hydrogenated block copolymer (A2).
Next, the same operation as in Example 1 was performed except that the blending of the obtained hydrogenated block copolymer (A2) and the base oil was as shown in Table 2, to obtain an oil composition, which was described above. Evaluation was performed. The results are shown in Table 2.

Example 3
A hydrogenated block copolymer (A3) and an oil composition were produced in the same manner as in Example 2 except that the formulation described in Table 1 was followed, and the above evaluation was performed. The results are shown in Tables 1 and 2.

Example 4
A hydrogenated block copolymer (A4) and an oil composition were produced in the same manner as in Example 1 except that the formulation described in Table 1 was followed, and the above evaluation was performed. The results are shown in Tables 1 and 2.

Example 5
In a pressure-resistant container purged with nitrogen and dried, 62.4 kg of cyclohexane as a solvent and 118.4 g of sec-butyllithium (10.5 mass% cyclohexane solution) as an anionic polymerization initiator were charged and heated to 50 ° C., Poly (β-farnesene / butadiene) -polystyrene diblock was prepared by adding a mixture of β-farnesene (5.43 kg) and butadiene (4.32 kg) and polymerizing for 2 hours, and subsequently adding 5.85 kg of styrene and polymerizing for 1 hour. A reaction solution containing a copolymer was obtained. To this reaction solution, 5% by mass of palladium carbon (palladium supported amount: 5% by mass) as a hydrogenation catalyst was added to the block copolymer, and the reaction was performed for 10 hours under conditions of a hydrogen pressure of 2 MPa and 150 ° C. . After allowing to cool and release the pressure, palladium carbon is removed by filtration, the filtrate is concentrated, and further dried under vacuum to obtain a hydrogenated poly (β-farnesene / butadiene) -polystyrene diblock copolymer (hereinafter, “ Hydrogenated block copolymer (A5) ”) was obtained. Table 1 shows the blending of various raw materials and the measurement results of various physical properties of the obtained hydrogenated block copolymer (A5).
Next, the same operation as in Example 1 was performed except that the blending of the obtained hydrogenated block copolymer (A5) and the base oil was as shown in Table 2, to obtain an oil composition, which was described above. Evaluation was performed. The results are shown in Table 2.

Example 6
Except that the blending of the hydrogenated block copolymer (A5) and the base oil was as shown in Table 2, the same operation as in Example 5 was performed to obtain an oil composition, and the above evaluation was performed. The results are shown in Table 2.

Example 7
In a pressure vessel that was purged with nitrogen and dried, 62.4 kg of cyclohexane as a solvent and 104.9 g of sec-butyllithium (10.5 mass% cyclohexane solution) as an anionic polymerization initiator were charged and heated to 50 ° C., Poly (β-farnesene / isoprene) -polystyrene diblock was obtained by adding a mixture of 4.88 kg of β-farnesene and 4.88 kg of isoprene and polymerizing for 2 hours, followed by adding 5.85 kg of styrene and polymerizing for 1 hour. A reaction solution containing a copolymer was obtained. To this reaction solution, 5% by mass of palladium carbon (palladium supported amount: 5% by mass) as a hydrogenation catalyst was added to the block copolymer, and the reaction was performed for 10 hours under conditions of a hydrogen pressure of 2 MPa and 150 ° C. . After allowing to cool and release the pressure, palladium carbon is removed by filtration, the filtrate is concentrated, and further dried under vacuum to obtain a hydrogenated poly (β-farnesene / isoprene) -polystyrene diblock copolymer (hereinafter, “ Hydrogenated block copolymer (A6) ”) was obtained. Table 1 shows the blending of various raw materials and the measurement results of various physical properties of the obtained hydrogenated block copolymer (A6).
Next, the same operation as in Example 1 was carried out except that the blend of the obtained hydrogenated block copolymer (A6) and the base oil was as shown in Table 2, to obtain an oil composition, which was described above. Evaluation was performed. The results are shown in Table 2.

Example 8
Except that the blending of the hydrogenated block copolymer (A6) and the base oil was as shown in Table 2, the same operation as in Example 7 was performed to obtain an oil composition, and the above evaluation was performed. The results are shown in Table 2.

[Comparative Example 1]
In a pressure vessel that was purged with nitrogen and dried, 62.4 kg of cyclohexane as a solvent and 98.6 g of sec-butyllithium (10.5 mass% cyclohexane solution) as an anionic polymerization initiator were charged and heated to 50 ° C., 8.36 kg of isoprene was added and polymerized for 2 hours, and then 5.34 kg of styrene was added and polymerized for 1 hour to obtain a reaction solution containing a polyisoprene-polystyrene diblock copolymer. To the reaction solution, 5% by mass of palladium carbon (palladium supported amount: 5% by mass) as a hydrogenation catalyst was added to the block copolymer, and the reaction was performed for 10 hours under the conditions of a hydrogen pressure of 2 MPa and 150 ° C. . After allowing to cool and release the pressure, palladium carbon is removed by filtration, the filtrate is concentrated, and further dried under vacuum to obtain a hydrogenated polyisoprene-polystyrene diblock copolymer (hereinafter referred to as “hydrogenated block copolymer”). (B1) ”). Table 1 shows the blending of various raw materials and measurement results of various physical properties of the obtained hydrogenated block copolymer (B1).
Subsequently, except having used the obtained hydrogenated block copolymer (B1) as a viscosity index improver, operation similar to Example 1 was performed, the oil composition was obtained, and evaluation mentioned above was performed. The results are shown in Table 2.

[Comparative Example 2]
Except that the blending of the hydrogenated block copolymer (B1) and the base oil was as shown in Table 2, the same operation as in Comparative Example 1 was performed to obtain an oil composition, and the above evaluation was performed. The results are shown in Table 2.

[Comparative Example 3]
A hydrogenated block copolymer (B2) and an oil composition were produced in the same manner as in Comparative Example 1 except that the composition described in Table 1 was followed, and the above evaluation was performed. The results are shown in Tables 1 and 2.

[Comparative Example 4]
A pressure-resistant vessel purged with nitrogen and dried was charged with 62.4 kg of cyclohexane as a solvent, 79.4 g of sec-butyllithium (10.5 mass% cyclohexane solution) as an anionic polymerization initiator, and 375 g of tetrahydrofuran as a Lewis base, and 50 ° C. Then, 0.47 kg of styrene (1) was added and polymerized for 1 hour, followed by addition of a mixture of 6.86 kg of isoprene and 6.86 kg of butadiene, followed by polymerization for 2 hours, and further styrene (2) 1. A reaction solution containing polystyrene-poly (isoprene / butadiene) -polystyrene triblock copolymer was obtained by adding 40 kg and polymerizing for 1 hour. To the reaction solution, 5% by mass of palladium carbon (palladium supported amount: 5% by mass) as a hydrogenation catalyst was added to the block copolymer, and the reaction was performed for 10 hours under the conditions of a hydrogen pressure of 2 MPa and 150 ° C. . After allowing to cool and release the pressure, the palladium carbon is removed by filtration, the filtrate is concentrated, and further dried under vacuum to obtain a hydrogenated polystyrene-poly (isoprene / butadiene) -polystyrene triblock copolymer (hereinafter, “ Hydrogenated block copolymer (B3) ”) was obtained. Table 1 shows the blending of various raw materials and measurement results of various physical properties of the obtained hydrogenated block copolymer (B3).
Next, the same operation as in Example 1 was performed except that the blending of the obtained hydrogenated block copolymer (B3) and the base oil was as shown in Table 2, to obtain an oil composition, which was described above. Evaluation was performed. The results are shown in Table 2.

[Comparative Example 5]
The above-described evaluation was performed using the base oil (paraffinic oil “Diana Fresia S-32” manufactured by Idemitsu Kosan Co., Ltd.) as Comparative Example 5 as it was. The results are shown in Table 2.

  From Tables 1 and 2, the hydrogenated block copolymers of Examples 1 to 8 are viscosity index improvers produced from plant-derived raw materials (β-farnesene), but the viscosity index of oil and high temperature and high shear. Excellent viscosity improvement effect. Moreover, it turns out that it is excellent in the viscosity index improvement effect of oil more than the case where the hydrogenated block copolymer of Comparative Examples 1-4 is used. Furthermore, since the hydrogenated block copolymers of Examples 2 to 8 have sufficiently low kinematic viscosities at 40 ° C. and 100 ° C., they are excellent in the fuel saving effect of automobiles.

Claims (12)

A viscosity index improver comprising a hydrogenated product of a copolymer comprising a structural unit (a) derived from an aromatic vinyl compound and a structural unit (b) derived from a conjugated diene,
The content of the structural unit (b1) derived from farnesene is 1 to 100% by mass in the total amount of the structural unit (b) derived from conjugated diene, and the content of the structural unit (b2) derived from conjugated diene other than farnesene Is 0 to 99 mass%,
A viscosity index improver in which the carbon-carbon double bond in the structural unit (b) derived from the conjugated diene is hydrogenated by 50 mol% or more.   The mass ratio [(a) / (b)] of the total amount of the structural unit (a) derived from the aromatic vinyl compound and the total amount of the structural unit (b) derived from the conjugated diene is 1/99 to 99/1. The viscosity index improver according to claim 1.   The viscosity index improver according to claim 1 or 2, wherein the farnesene is β-farnesene.   The viscosity index improver according to any one of claims 1 to 3, wherein the peak top molecular weight (Mp) is 4,000 to 1,500,000.   The viscosity index improver according to any one of claims 1 to 4, wherein the molecular weight distribution (Mw / Mn) is 1 to 4.   The viscosity index improver according to any one of claims 1 to 5, wherein the aromatic vinyl compound is styrene.   The viscosity index improver according to any one of claims 1 to 6, wherein the conjugated diene other than farnesene is at least one selected from the group consisting of isoprene, butadiene and myrcene.   A block copolymer comprising a polymer block (A) mainly composed of the structural unit (a) derived from the aromatic vinyl compound and a polymer block (B) mainly composed of the structural unit (b) derived from the conjugated diene The viscosity index improver according to any one of claims 1 to 7, comprising a combined hydrogenated product.   The viscosity index improver according to claim 8, wherein the carbon-carbon double bond in the polymer block (B) is hydrogenated by 50 mol% or more.   An oil composition comprising a base oil and the viscosity index improver according to any one of claims 1 to 9.   A polymerization step for obtaining a copolymer containing a structural unit (a) derived from an aromatic vinyl compound and a structural unit (b) derived from a conjugated diene by anionic polymerization, and carbon-carbon in the structural unit (b) derived from the conjugated diene The manufacturing method of the viscosity index improver in any one of Claims 1-9 which has the process of hydrogenating a double bond 50 mol% or more.   A block copolymer comprising a polymer block (A) mainly comprising a structural unit (a) derived from an aromatic vinyl compound and a polymer block (B) mainly comprising a structural unit (b) derived from the conjugated diene The viscosity index improver according to claim 11, which comprises a polymerization step of obtaining a polymer by anionic polymerization, and a step of hydrogenating at least 50 mol% of carbon-carbon double bonds in the structural unit (b) derived from the conjugated diene. Production method.