JP2023033962A - Lubricant viscosity index improver and use of the same - Google Patents

Abstract

To provide a lubricant viscosity index improver, a lubricant additive composition and a lubricant composition that maintain transparency and have excellent low-temperature viscosity.SOLUTION: The present invention relates to a lubricant viscosity index improver comprising a propylene/cyclic olefin copolymer having the following requirements. (x-1) A content ratio of a propylene-derived constitutional unit falls within a range of 75 mol% or more to less than 100 mol%. (x-2) A cyclic olefin has a specific structure. (x-3) A glass transition temperature (Tg) measured with a differential scanning calorimeter is 0°C or higher. (x-4) A melting point (Tm) measured with the differential scanning calorimeter is not observed between 0°C and 160°C. (x-5) An intrinsic viscosity [η] measured in decalin at 135°C falls within the range of 0.65 to 2.5 dl/g. (x-6) Triad tacticity calculated by 13C-NMR falls within the following range. A mm molar fraction is 0%<mm<25%, and a rr molar fraction is 30%<rr<60%.SELECTED DRAWING: None

Description

The present invention relates to a lubricating oil viscosity index improver, a lubricating oil additive composition containing the lubricating oil viscosity index improver, and a lubricating oil composition.

Petroleum products generally have so-called temperature dependence of viscosity, in which the viscosity changes greatly when the temperature changes. For example, lubricating oils used in automobiles preferably have low temperature dependence of viscosity (that is, have a high viscosity index). Therefore, in lubricating oils, certain polymers soluble in lubricating base oils are used as viscosity modifiers (also referred to as viscosity index improvers) for the purpose of reducing the temperature dependence of viscosity.

Ethylene/α-olefin copolymers are widely used as viscosity index improvers for lubricating oils, and various improvements have been made to further improve the performance balance of lubricating oils (see, for example, Patent Document 1). It has also been proposed to use a propylene/α-olefin copolymer as a viscosity index improver for lubricating oils (see, for example, Patent Document 2).

2. Description of the Related Art In recent years, as demand for reducing the environmental load of automobiles has increased, there has been a strong demand for improving the fuel efficiency of automobiles. In particular, reduction of viscous resistance in a wide temperature range from low to high is mentioned as one of measures to save fuel consumption by using engine oil.

As an engine oil viscosity modifier (VM: abbreviation of Viscosity Modifier), a VM with a high viscosity index is required for the purpose of improving fuel efficiency. As one method for increasing the viscosity index of VM, there is a method for increasing the cohesive force of VM in order to reduce the viscosity of lubricating oil in a low temperature (40° C.) region. However, at the same time, it is also required that the blended oil has good transparency. In order to improve the cohesive force at low temperatures, it is conceivable to lower the compatibility of VM with oils such as base oils, but it is necessary to maintain the compatibility from the viewpoint of transparency. The challenge was to achieve both physical properties.

WO2006/101206 Japanese Patent Publication No. 2013-506036

An object of the present invention is to obtain a lubricating oil viscosity index improver, a lubricating oil additive composition and a lubricating oil composition which are excellent in low-temperature viscosity while maintaining transparency.

The present invention relates to a lubricating oil viscosity index improver comprising a propylene/cyclic olefin copolymer (X) having the following requirements (x-1) to (x-6).
(x-1) The content of propylene-derived structural units is in the range of 75 mol% or more and less than 100 mol%.
(x-2) The cyclic olefin has a structure represented by general formula (I).
(x-3) The glass transition temperature (Tg) measured with a differential scanning calorimeter is 0° C. or higher.
(x-4) Melting point (Tm) measured with a differential scanning calorimeter is not observed between 0°C and 160°C.
(x-5) The intrinsic viscosity [η] measured in decalin at 135°C is in the range of 0.65 to 2.5 dl/g.
(x-6) The triad tacticity calculated by ¹³ C-NMR is within the following range.
The mm fraction is 0%<mm<25% and the rr fraction is 30%<rr<60%.

〔式中、Ｒ₁～Ｒ₆は互いに同一でも異なっていてもよく、水素原子、ハロゲン原子、メチル基、エチル基、あるいはＲ₁とＲ₂、Ｒ₃とＲ₄、Ｒ₅とＲ₆でそれぞれ炭素数１～２のアルキリデン基を形成していてもよい。〕

[In the formula, R ₁ to R ₆ may be the same or different, and a hydrogen atom, a halogen atom, a methyl group, an ethyl group, or R ₁ and R ₂ , R ₃ and R ₄ , R ₅ and R ₆ Each may form an alkylidene group having 1 to 2 carbon atoms. ]

The lubricating oil viscosity index improver containing the propylene/cyclic olefin copolymer (X) of the present invention has excellent solubility in oils such as the base oil (B), and can be pelletized (granulated). Therefore, it is excellent in handleability.

In addition, since the lubricating oil additive composition and the lubricating oil composition of the present invention contain the propylene/cyclic olefin copolymer (X), they have high cohesive force in the low temperature range (−40° C.), resulting in good low-temperature viscosity. have

<<Propylene/Cyclic Olefin Copolymer (X)>>
The propylene/cyclic olefin copolymer (X) contained in the lubricating oil viscosity index improver of the present invention (hereinafter sometimes referred to as "copolymer (X)"). ] has the following requirements (x-1) to (x-6).

Requirement (x-1)
The content of the propylene-derived structural units constituting the copolymer (X) is 75 mol% or more and less than 100 mol%, preferably 77 to 95 mol% [however, the propylene-derived structural units and the cyclic olefin-derived structural units is 100 mol %. ].
Copolymers containing less than 75 mol % of propylene-derived structural units have low compatibility with the base oil (B), and may cause cloudiness and precipitation.

Requirement (x-2)
A cyclic olefin constituting the copolymer (X) has a structure represented by the general formula (I).

〔式中、Ｒ₁～Ｒ₆は互いに同一でも異なっていてもよく、水素原子、ハロゲン原子、メチル基、エチル基、あるいはＲ₁とＲ₂、Ｒ₃とＲ₄、Ｒ₅とＲ₆でそれぞれ炭素数１～２のアルキリデン基を形成していてもよい。〕

[In the formula, R ₁ to R ₆ may be the same or different, and a hydrogen atom, a halogen atom, a methyl group, an ethyl group, or R ₁ and R ₂ , R ₃ and R ₄ , R ₅ and R ₆ Each may form an alkylidene group having 1 to 2 carbon atoms. ]

Specifically, the cyclic olefin having the structure represented by the general formula (I) according to the present invention includes bicyclo[2.2.1]hept-2-ene derivatives, tetracyclo[4.4.0.12,5.17,10]- 3-dodecene derivative, hexacyclo[6.6.1.13,6.110,13.02,7.09,14]-4-heptadecene derivative, octacyclo[8.8.0.12,9.14,7.111,18.113,16.03,8.012,17]-5-docosene derivative, pentacyclo [6.6.1.13,6.02,7.09,14]-4-hexadecene derivative, heptacyclo-5-eicosene derivative, heptacyclo-5-heneicosene derivative, tricyclo[4.3.0.12,5]-3-decene derivative, tricyclo[4.4.0.12 ,5]-3-undecene derivative, pentacyclo[6.5.1.13,6.02,7.09,13]-4-pentadecene derivative, pentacyclopentadecadiene derivative, pentacyclo[7.4.0.12,5.19,12.08,13]-3-pentadecene derivatives, heptacyclo[8.7.0.13,6.110,17.112,15.02,7.011,16]-4-eicosene derivatives, nonacyclo[10.9.1.14,7.113,20.115,18.03,8.02,10.012,21.014,19]-5-pentacosene derivatives, pentacyclo[8.4.0.12,5.19,12.08,13]-3-hexadecene derivatives, heptacyclo[8.8.0.14,7.111,18.113,16.03,8.012,17]-5-heneicosene derivatives, nonacyclo[10.10.1.15,8.114,21.116, 19.02,11.04,9.013,22.015,20]-5-hexacosene derivatives, 1,4-methano-1,4,4a,9a-tetrahydrofluorene derivatives, 1,4-methano-1,4,4a,5,10, 10a-hexahydroanthracene derivatives, cyclopentadiene-acenaphthylene adducts, and the like.

Among these cyclic olefins, tetracyclododecene has a rigid skeleton, which has the effect of lowering compatibility with the base oil (B). A polymer can be obtained.

Requirement (x-3)
The glass transition temperature (Tg) measured by a differential scanning calorimeter (DSC) is 0°C or higher, preferably in the range of 20 to 120°C.

A polymer whose Tg satisfies the above range can be treated as a glassy solid at around room temperature, and can be easily dissolved in the base oil (B) at a high temperature (to the extent that the low-boiling component of the base oil does not evaporate). .
The glass transition temperature (Tg) of the copolymer (X) according to the invention was measured with a differential scanning calorimeter (DSC).

The measurement method with a differential scanning calorimeter (DSC) is as follows.
A differential scanning calorimeter manufactured by SII (DSC7020) calibrated with an indium standard was used. Weigh the measurement sample onto an aluminum DSC pan to approximately 10 mg. A lid is crimped onto the pan to provide a closed atmosphere and a sample pan. Place the sample pan in the DSC cell and place an empty aluminum pan as a reference. The DSC cell is heated from 30° C. (room temperature) to 250° C. at a rate of 10° C./min in a nitrogen atmosphere (first temperature rising process). After holding the temperature at 250° C. for 5 minutes, the temperature is lowered at a rate of 10° C./min to cool the DSC cell to 70° C. (temperature lowering process). The glass transition point (Tg ).

Requirement (x-4)
Melting point (Tm) measured by differential scanning calorimeter (DSC) is not observed between 0°C and 160°C.

Since the melting point is not within the above range, the copolymer does not crystallize in the blended oil, and white turbidity due to precipitation of crystals does not occur.
The melting point (Tm) and heat of crystal fusion (ΔH) of the copolymer (X) according to the present invention were measured under the following conditions.

Using a differential scanning calorimeter (DSC7020) manufactured by SII, about 10 mg of a sample was heated from 30° C. to 250° C. at a heating rate of 10° C./min under a nitrogen atmosphere, and held at that temperature for 5 minutes. Further, the temperature was lowered to 70°C at a temperature drop rate of 10°C/min, held at that temperature for 5 minutes, and then heated to 250°C at a temperature increase rate of 10°C/min. The endothermic peak observed during the second temperature rise was defined as the melting peak, and the temperature at which the melting peak appeared was determined as the melting point (Tm). The heat of fusion ΔH was obtained by calculating the area of the melting peak. When the melting peaks were multimodal, the total area of the melting peaks was calculated.

Requirement (x-5)
The limiting viscosity [η] measured in decalin at 135° C. is in the range of 0.65 to 2.5 dl/g, preferably 0.80 to 1.50 dl/g.
When the intrinsic viscosity [η] is within the above range, it has a thickening property and excellent solubility in the base oil (B).

Requirement (x-6)
The triad tacticity calculated by ¹³ C-NMR is in the following range.
The mm fraction is 0%<mm<25% and the rr fraction is 30%<rr<60%.

The triad tacticity of the copolymer (X) according to the present invention is determined by the ¹³ C-NMR spectrum of the copolymer and the following formula (1). It is obtained as the strength (area) ratio of the side chain methyl group of .
rr fraction (%) = PPP (rr) x 100/
{PPP (mm) + PPP (mr) + PPP (rr)} (1)
(Wherein, PPP (mm), PPP (mr), and PPP (rr) are the second units of the head-to-tail linked propylene unit triad observed in the following shift regions of the ¹³ C-NMR spectrum. It is the area of the side chain methyl group.)

Such PPP(mm), PPP(mr) and PPP(rr) each represent a head-to-tail propylene triunit chain of the following structure.

Each carbon peak in the spectrum can be attributed with reference to the literature (Polymer, 30, 1350 (1989)).
Triad tacticity is measured by heating and dissolving 0.35 g of a sample in 2.0 ml of hexachlorobutadiene. After filtering this solution with a glass filter (G2), 0.5 ml of deuterated benzene is added, and an NMR tube with an inner diameter of 10 mm is charged. Then, ¹³ C-NMR measurement is performed at 120° C. using a JEOL GX-500 type NMR spectrometer. The cumulative number of times shall be 10,000 or more.

The copolymer (X) according to the present invention is not particularly limited, but preferably has an SP value in the range of 16.0 to 18.8 (the calculation method of the SP value is described later in Examples).
When the lubricating oil viscosity index improver containing the copolymer (X) of the present invention is used as a lubricating oil additive composition or a lubricating oil composition, the lubricating oil additive composition or the lubricating oil composition is usually obtained by mixing with the base oil (B) described later.

Since the SP value of the base oil (B) is usually 15.9 to 16.0 when estimated by the same method, the copolymer (X) having the SP value in the above range has an approximate SP value. Therefore, the compatibility is excellent and the transparency of the lubricating oil additive composition or the lubricating oil composition is improved, which is preferable.

<<Method for Producing Propylene/Cyclic Olefin Copolymer (X)>>
The propylene/cyclic olefin copolymer (X) according to the present invention can be produced by various known production methods, for example, a compound containing a transition metal such as vanadium, zirconium, titanium, hafnium, an organic aluminum compound, an organic aluminum oxy compound and a It can be produced by copolymerizing propylene and the above cyclic olefin using a catalyst containing at least one selected from ionized ionic compounds. More specifically, it can be produced according to JP-A-2000-264925.

<Viscosity index improver for lubricating oil>
The lubricating oil viscosity index improver of the present invention is a composition containing the propylene/cyclic olefin copolymer (X). You may use it in the state diluted to B).

When diluted with the base oil (B) and used, the propylene/cyclic olefin copolymer (X) is usually contained in the range of 1 to 50% by mass.
Since the lubricating oil viscosity index improver of the present invention contains the propylene/cyclic olefin copolymer (X), it is excellent in handleability.

<Additive composition for lubricating oil>
The lubricating oil additive composition of the present invention contains 1 to 50% by mass, preferably 1 to 20% by mass, and preferably 1 to 20% by mass of the propylene/cyclic olefin copolymer (X), and 50 to 99% by mass of the base oil (B). , preferably 80 to 99 mass % [however, the mass % of (X) and (B) is calculated based on the total amount of (X) and (B) in the additive composition. ] is a composition containing

The lubricating oil additive composition of the present invention usually does not contain the pour point depressant (C) and other components (additives) described later, or if necessary, 0.01 to 0.01 of the antioxidant described later. It is generally contained in the range of 1% by mass, preferably 0.05 to 0.5% by mass.
Since the lubricating oil additive composition of the present invention contains the copolymer (X) in the above range, it is excellent in handleability.

《Base oil (B)》
The base oil (B), which is the main component of the lubricating oil additive composition of the present invention, preferably satisfies the following requirement (B-1).

[Requirements (B-1)]
100° C. kinematic viscosity is in the range of 1 to 50 mm ² /s.
Base oils (B) according to the present invention include mineral oils; and synthetic oils such as poly-α-olefins, diesters and polyalkylene glycols.

Mineral oil or a blend of mineral oil and synthetic oil may be used as the base oil (B) according to the present invention. Examples of diesters include polyol esters, dioctyl phthalate, dioctyl sebacate and the like.

Mineral oil is generally used after a refining process such as dewaxing, and there are several grades depending on the refining method. Mineral oils with a wax content of 0.5 to 10% are generally used. For example, a highly refined oil having a low pour point, a high viscosity index, and a composition mainly composed of isoparaffins produced by a hydrocracking refining method can also be used. Mineral oils with kinematic viscosities of 10 to 200 mm ² /s at 40° C. are commonly used.

As described above, mineral oil is generally used after undergoing a refining process such as dewaxing, and there are several grades depending on the method of refining, and this grade is defined by the API (American Petroleum Institute) classification. Table 2 shows the properties of the lubricating oil bases classified into each group.

＊１：ＡＳＴＭ Ｄ４４５（ＪＩＳ Ｋ２２８３）に準じて測定
＊２：ＡＳＴＭ Ｄ３２３８に準じて測定
＊３：ＡＳＴＭ Ｄ４２９４（ＪＩＳ Ｋ２５４１）に準じて測定
＊４：飽和炭化水素分が９０ｖｏｌ％未満でかつ硫黄分が０．０３重量％未満
または飽和炭化水素分が９０ｖｏｌ％以上でかつ硫黄分が０．０３重量
％を超える鉱物油もグループＩに含まれる。

*1: Measured according to ASTM D445 (JIS K2283) *2: Measured according to ASTM D3238 *3: Measured according to ASTM D4294 (JIS K2541) *4: Saturated hydrocarbon content is less than 90 vol% and sulfur content Also included in Group I are mineral oils with less than 0.03 wt.

The polyα-olefin in Table 2 is a hydrocarbon-based polymer obtained by polymerizing an α-olefin having at least 10 carbon atoms or more as one of raw material monomers, such as polydecene obtained by polymerizing 1-decene. are exemplified.

The base oil (B) is preferably a mineral oil belonging to group (II) or group (III), or a polyα-olefin belonging to group (IV). Groups (II) and (III) tend to have lower wax concentrations than group (I). Among mineral oils belonging to Group (II) or Group (III), those having a kinematic viscosity at 100° C. of 1 to 50 mm ² /s are preferred.

<Lubricating oil composition>
The lubricating oil composition of the present invention is a lubricating oil composition containing the propylene/cyclic olefin copolymer (X) and the base oil (B), wherein 100% by mass of the lubricating oil composition contains the propylene/cyclic The composition contains 0.01 to 30% by mass, preferably 0.01 to 5% by mass, of the olefin copolymer (X).
The lubricating oil composition of the present invention contains an ashless dispersant, a pour point depressant (C), and other components (additives) in addition to the copolymer (X) and base oil (B).

《Ashless dispersant》
Ashless dispersants, one of the components included in the lubricating oil compositions of this invention, are characterized by a polar group attached to a relatively high molecular weight hydrocarbon chain. Typical ashless dispersants include nitrogen-containing dispersants such as N-substituted long chain alkenyl succinimides, also known as succinimide dispersants. Succinimide dispersants are more fully described in US Pat. Nos. 4,234,435 and 3,172,892. Another class of ashless dispersants are high molecular weight esters prepared by the reaction of polyhydric fatty alcohols such as glycerol, pentaerythritol and sorbitol with hydrocarbyl acylating agents. Such materials are described in more detail in US Pat. No. 3,381,022. Another class of ashless dispersants are Mannich bases. These are materials formed by the condensation of high molecular weight alkyl-substituted phenols, alkylene polyamines, and aldehydes such as formaldehyde, and are described in more detail in US Pat. No. 3,634,515.
When the lubricating oil composition of the present invention contains an ashless dispersant, it is 0.1% by mass or less, more preferably 0.05% by mass or less, based on 100% by mass of the lubricating oil composition.

<<Pour point depressant (C)>>
The lubricating oil composition of the present invention may further contain a pour point depressant (C). The content of the pour point depressant (C) is not particularly limited as long as the effect of the present invention is exhibited, but usually 0.05 to 5% by mass, preferably 0.05 to 3% by mass in 100% by mass of the lubricating oil composition %, more preferably 0.05 to 2 mass %, and still more preferably 0.05 to 1 mass %.

Pour point depressants (C) that may be contained in the lubricating oil composition of the present invention include alkylated naphthalenes, alkyl methacrylate (co)polymers, alkyl acrylate (co)polymers, and alkyl fumarate. and vinyl acetate copolymers, α-olefin polymers, α-olefin-styrene copolymers, and the like. In particular, alkyl methacrylate (co)polymers and alkyl acrylate (co)polymers may be used.

<Other components (additives)>
In addition, the lubricating oil composition of the present invention may contain components (additives) other than the copolymer (X) and the base oil (B). Any one or more of the materials described below may be arbitrarily included as other components.

When the lubricating oil composition of the present invention contains additives, the content is not particularly limited. usually exceeds 0% by mass, preferably 1% by mass or more, more preferably 3% by mass or more, and still more preferably 5% by mass or more. The content of the additive is usually 40% by mass or less, preferably 30% by mass or less, more preferably 20% by mass or less, and still more preferably 15% by mass or less.

One such additive is a detergent. Many of the conventional detergents used in the engine lubrication field are based on basic metal compounds (typically metal hydroxides, oxides and carbonates based on metals such as calcium, magnesium and sodium). salt) imparts basicity or TBN to the lubricating oil. Such metallic overbased detergents (also called overbased salts or overbased salts) are generally neutralized according to the stoichiometry of the metal and the specific acidic organic compound that reacts with the metal. It is a single phase homogeneous Newtonian system characterized by a metal content in excess of what is believed to be present for the purpose. Overbased materials combine acidic materials (typically inorganic acids and lower carboxylic acids such as carbon dioxide) with acidic organic compounds (also called substrates) and a stoichiometric excess of metals. It is typically prepared by reacting a mixture of salts, typically in an organic solvent inert to acidic organic substrates (eg mineral oil, naphtha, toluene, xylene, etc.). Accelerators such as phenols and alcohols are optionally present in small amounts. Acidic organic matrices will usually have a sufficient number of carbon atoms to confer some degree of solubility in oil.

Such conventional overbased materials and methods for their preparation are well known to those skilled in the art. Patents describing techniques for making basic metal salts of sulfonic acids, carboxylic acids, phenols, phosphoric acids, and mixtures of two or more thereof include U.S. Pat. Nos. 2,501,731; 2,616,925; 2,777,874; 3,256,186; 3,384,585; 3,365,396 3,320,162; 3,318,809; 3,488,284; and 3,629,109. Salixarate detergents are described in US Pat. No. 6,200,936 and WO 01/56968. Saligenin detergents are described in US Pat. No. 6,310,009.

The amount of a typical detergent in a lubricating oil composition is not particularly limited as long as the effect of the present invention is exhibited, but is usually 1 to 10% by mass, preferably 1.5 to 9.0% by mass, more preferably 2% by mass. .0 to 8.0% by mass. It should be noted that all such amounts are based on no oil (ie, no diluent oil as they are conventionally supplied).

In addition to the above ashless dispersants, polymer dispersants and polyhydric dispersant additives may be used.
Dispersants, such as the ashless dispersants described above, may be post-treated by reacting with any of a variety of materials. These include urea, thiourea, dimercaptothiadiazole, carbon disulfide, aldehydes, ketones, carboxylic acids, hydrocarbon-substituted succinic anhydrides, nitriles, epoxides, boron compounds, and phosphorus compounds. is given. A reference detailing such processing is found in US Pat. No. 4,654,403. The amount of the dispersant in the composition of the present invention is not particularly limited as long as the effect of the present invention is exhibited, but typically 1 to 10% by mass, preferably 1.5 to 9.0% by mass, more preferably can range from 2.0 to 8.0% by weight (all on an oil-free basis).

Another component is an antioxidant. Antioxidants include phenolic antioxidants, which may include butyl-substituted phenols having 2-3 t-butyl groups. The para position may be occupied by a hydrocarbyl group or a group linking two aromatic rings. The latter antioxidants are described in more detail in US Pat. No. 6,559,105. Antioxidants also include aromatic amines such as nonylated diphenylamine. Other antioxidants include sulfurized olefins, titanium compounds, and molybdenum compounds. For example, US Pat. No. 4,285,822 discloses a lubricating oil composition comprising a composition containing molybdenum and sulfur. Typical amounts of antioxidants will of course depend on the specific antioxidants and their individual effectiveness, but an exemplary total amount is 0.01 to 5% by weight, preferably 0.15%. It can be up to 4.5% by weight, more preferably 0.2-4% by weight. Additionally, one or more antioxidants may be present, and certain combinations of these may be synergistic to their combined overall effect.

Thickeners (sometimes also referred to as viscosity index improvers or viscosity modifiers) may be included in the lubricating oil additive composition. Thickeners are usually polymeric and include polyisobutenes, polymethacrylates, diene polymers, polyalkylstyrenes, esterified styrene-maleic anhydride copolymers, alkenylarene conjugated diene copolymers and Examples include polyolefins, hydrogenated SBR (styrene-butadiene rubber), SEBS (styrene-ethylene-butylene-styrene block copolymer), and the like. Multifunctional thickeners that also have dispersant and/or antioxidant properties are known and may optionally be used.

Another additive is an antiwear agent. Examples of antiwear agents include metal thiophosphates, phosphate esters and their salts, phosphorus-containing carboxylic acids, esters, ethers, amides; and phosphorus-containing antiwear agents such as phosphites. / extreme pressure agents. In a specific embodiment, the phosphorus wear inhibitor is not particularly limited as long as the effect of the present invention is exhibited, but is usually 0.01 to 0.2% by mass, preferably 0.015 to 0.15% by mass, more preferably It may be present in an amount to provide 0.02 to 0.1 wt%, more preferably 0.025 to 0.08 wt% phosphorous.

Often the antiwear agent is a zinc dialkyldithiophosphate (ZDP). A typical ZDP may contain 11 wt% P (calculated on an oil-free basis), and a suitable amount may include 0.09-0.82 wt%. Phosphorus-free antiwear agents include borate esters (including borate epoxides), dithiocarbamate compounds, molybdenum-containing compounds, and sulfurized olefins.

Other additives that may optionally be used in the lubricating oil composition include the extreme pressure agents and antiwear agents mentioned above, as well as friction modifiers, color stabilizers, rust inhibitors, metal deactivators and antifoam agents. and each may be used in a conventionally known amount.

<Method for producing lubricating oil composition>
The lubricating oil composition of the present invention can be prepared by mixing copolymer (X) and base oil (B), optionally with other desired ingredients, by methods known in the art. Copolymer (X) may optionally be supplied as a concentrate in base oil (B) for ease of handling.

<Application of lubricating oil composition>
The lubricating oil composition of the present invention includes, for example, engine oils for automobiles, lubricating oils for heavy-duty diesel engines, lubricating oils for marine diesel engines, lubricating oils for two-stroke engines, automatic transmissions and manual transmissions. It can be used to lubricate any of a variety of known mechanical devices such as machine lubricants, gear lubricants and greases.

EXAMPLES The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.
Polymers containing propylene/cyclic olefin copolymers contained in viscosity index improvers for lubricating oils used in Examples and Comparative Examples were polymers obtained in the following production examples.

The following compounds were used as the catalysts used in the production examples.
Catalyst: Macromolecules 1998, 31, 2395. (tert-Butylamido)dimethyl(fluorenyl)silanetitanium dimethyl synthesized according to the method described was used as catalyst.

(1) Propylene Homopolymer [Production Example 1]
A dry pressure-resistant autoclave with an internal volume of 2.0 L is sufficiently purged with nitrogen, and 750 mL of a dehydrated and purified cyclohexane/hexane (9/1) mixed solution and 0.1 mmol of triisobutylaluminum in terms of aluminum atoms are sequentially introduced under a nitrogen stream. bottom. Then, the temperature was raised to 50° C., and propylene was supplied so that the propylene partial pressure became 0.1 MPaG, and this state was maintained. Thereafter, 0.001 mmol of a catalyst was added, followed by 0.004 mmol of triphenylcarbenium tetrakis(pentafluorophenyl)borate to initiate polymerization. While maintaining the internal temperature at 50° C., propylene was supplied so that the propylene partial pressure was maintained at 0.1 MPaG, and polymerization was carried out for 5 minutes. After a predetermined time had passed, the supply of propylene was stopped and the polymerization was stopped by adding a small amount of methanol. The reactant was added to 3 liters of acetone/methanol (3/1) mixed solvent containing a small amount of hydrochloric acid to precipitate the polymer. After washing with the same solvent, it was dried under reduced pressure at 130° C. for 10 hours to obtain 13.5 g of a propylene homopolymer.

(2) Propylene/cyclic olefin copolymer (X-1)
[Production Example 2]
A dry pressure-resistant autoclave with an inner volume of 2.0 L was sufficiently purged with nitrogen, and 750 mL of a dehydrated and purified cyclohexane/hexane (9/1) mixed solution, 20 mmol of tetracyclododecene (TD), and 0 triisobutyl aluminum in terms of aluminum atoms. .5 mmol were sequentially inserted under a stream of nitrogen. Then, the temperature was raised to 50° C., and propylene was supplied so that the propylene partial pressure became 0.1 MPaG, and this state was maintained. Thereafter, 0.005 mmol of a catalyst was added, followed by 0.02 mmol of triphenylcarbenium tetrakis(pentafluorophenyl)borate to initiate polymerization. While maintaining the internal temperature at 50° C., propylene was supplied so that the propylene partial pressure was maintained at 0.1 MPaG, and polymerization was carried out for 10 minutes. After a predetermined time had passed, the supply of propylene was stopped and the polymerization was stopped by adding a small amount of methanol. The reactant was added to 3 liters of acetone/methanol (3/1) mixed solvent containing a small amount of hydrochloric acid to precipitate the polymer. After washing with the same solvent, it was dried under reduced pressure at 130° C. for 10 hours to obtain 2.76 g of a propylene/cyclic olefin copolymer (X-1).

(3) Propylene/cyclic olefin copolymer (X-2)
[Production Example 3]
1.14 g of a propylene/cyclic olefin copolymer (X-2) was obtained in the same manner as in Production Example 2 except that the amount of tetracyclododecene was changed to 40 mmol.

(4) Propylene/cyclic olefin copolymer (X-3)
[Production Example 4]
Tetracyclododecene was 160 mmol, triisobutylaluminum was 2.0 mmol in terms of aluminum atom, propylene partial pressure was 0.2 MPaG, catalyst was 0.02 mmol, and triphenylcarbenium tetrakis(pentafluorophenyl)borate was 0.08 mmol. 3.76 g of a propylene/cyclic olefin copolymer (X-3) was obtained by performing the same operation as in Production Example 2 except for the above.

(5) Propylene/cyclic olefin copolymer [Production Example 5]
2.61 g of a propylene/cyclic olefin copolymer was obtained in the same manner as in Production Example 4, except that tetracyclododecene was 300 mmol and the propylene partial pressure was 0.3 MPaG.

The physical properties of the polymer containing the propylene/cyclic olefin copolymer contained in the lubricating oil viscosity index improver used in Examples and Comparative Examples were measured by the following methods.

[Propylene content]
(measuring device)
Bruker Biospin AVANCEIIIcryo-500 type nuclear magnetic resonance apparatus (measurement conditions)
Measurement nucleus: ¹³ C (125 MHz), measurement mode: single pulse proton broadband decoupling, pulse width: 45° (5.00 μs), number of points: 64 k, observation range: 250 ppm (-55 to 195 ppm), repetition time: 5.5 seconds, number of times of accumulation: 128 times, measurement solvent: 1,1,2,2-tetrachloroethane-d2, sample concentration: ca. 60 mg/0.6 mL, measurement temperature: 120° C., window function: exponential (BF: 1.0 Hz), chemical shift standard: 1,1,2,2-tetrachloroethane-d2 (128.0 ppm).

[SP value (Hansen)]
The SP value in this specification refers to the Hansen Solubility Parameter, and refers to a value calculated by the following formula according to Hansen Solubility Parameter A User's Handbook (written by Charles M. Hansen, CRC Press; 1st Edition).
δ=((δD)2+(δP)2+(δH)2) 1/2
[Wherein, δ represents the SP value (ie, Hansen solubility parameter), δD represents the dispersion term, δP represents the polar term, and δH represents the hydrogen bonding term. ]

[mm fraction, rr fraction]
Measured by the method described above.
[Intrinsic viscosity [η]]
Measured by the method described above.

[Glass transition temperature (Tg)]
Measured by the method described above.
[Melting point (Tm), heat of crystal fusion (ΔH)]
Measured by the method described above.

[Viscosity index]
The viscosity index (VI) was calculated according to ASTM D2270 using the kinematic viscosity (KV) results of the lubricating oil compositions measured according to ASTM D445 at 40°C and 100°C.
[MR viscosity @ -40°C]
The MR viscosity (-40°C) of the lubricating oil composition is measured according to ASTM D4648.

[Example 1]
A lubricating oil composition was prepared using the propylene/cyclic olefin copolymer (X-1) obtained in Production Example 2 above as a viscosity modifier for a lubricating oil. The blending amount of the propylene/cyclic olefin copolymer was adjusted so that the kinematic viscosity at 100° C. of the lubricating oil composition was about 8.0 mm ² /s.

The formulation composition is as follows.
API group (III) base oil (“Yubase-4”, manufactured by SK Lubricants, kinematic viscosity at 100° C.: 4.21 mm ² /s, viscosity index: 123)
Additive ^* : 8.64% by mass
Pour point depressant: 0.3% by mass
(Polymethacrylate “Leblanc 165”, manufactured by Toho Chemical Industry Co., Ltd.)
Copolymer: As shown in Table 3.
Total 100.0 (% by mass)
Note (*) Additives = Ca and Na overbased detergents, N-containing dispersants, aminic and phenolic antioxidants, zinc dialkyldithiophosphates, friction modifiers, and defoamers. Conventional engine oil additive package for GF-5 containing.
The physical properties of the obtained lubricating oil viscosity index improver and lubricating oil composition were measured by the methods described above. Table 3 shows the results.

[Example 2]
Example 1 except that the propylene/cyclic olefin copolymer (X-2) obtained in Production Example 3 above was used instead of the propylene/cyclic olefin copolymer (X-1) used in Example 1. in the same manner as above to obtain a lubricating oil composition.
The physical properties of the obtained lubricating oil viscosity index improver and lubricating oil composition were measured by the methods described above. Table 3 shows the results.

[Example 3]
Example 1 except that the propylene/cyclic olefin copolymer (X-3) obtained in Production Example 4 above was used instead of the propylene/cyclic olefin copolymer (X-1) used in Example 1. in the same manner as above to obtain a lubricating oil composition.
The physical properties of the obtained lubricating oil viscosity index improver and lubricating oil composition were measured by the methods described above. Table 3 shows the results.

[Comparative Example 1]
In the same manner as in Example 1 except that the propylene homopolymer obtained in Production Example 1 was used instead of the propylene/cyclic olefin copolymer (X-1) used in Example 1, a lubricating oil composition was prepared. got stuff
The physical properties of the obtained lubricating oil viscosity index improver and lubricating oil composition were measured by the methods described above. Table 3 shows the results.

[Comparative Example 2]
The procedure of Example 1 was repeated except that the propylene/cyclic olefin copolymer (X-1) used in Example 1 was replaced with the propylene/cyclic olefin copolymer obtained in Production Example 5 above. A lubricating oil composition was obtained.
The physical properties of the obtained lubricating oil viscosity index improver and lubricating oil composition were measured by the methods described above. Table 3 shows the results.

Claims (6)

A lubricating oil viscosity index improver comprising a propylene/cyclic olefin copolymer (X) having the following requirements (x-1) to (x-6):
(x-1) The content of propylene-derived structural units is in the range of 75 mol% or more and less than 100 mol%.
(x-2) The cyclic olefin has a structure represented by general formula (I).
(x-3) The glass transition temperature (Tg) measured with a differential scanning calorimeter is 0° C. or higher.
(x-4) Melting point (Tm) measured with a differential scanning calorimeter is not observed between 0°C and 160°C.
(x-5) The intrinsic viscosity [η] measured in decalin at 135°C is in the range of 0.65 to 2.5 dl/g.
(x-6) The triad tacticity calculated by ¹³ C-NMR is within the following range.
The mm fraction is 0%<mm<25% and the rr fraction is 30%<rr<60%.

[In the formula, R ₁ to R ₆ may be the same or different, and a hydrogen atom, a halogen atom, a methyl group, an ethyl group, or R ₁ and R ₂ , R ₃ and R ₄ , R ₅ and R ₆ Each may form an alkylidene group having 1 to 2 carbon atoms. ] The viscosity index improver for lubricating oil according to claim 1, wherein the cyclic olefin of the propylene/cyclic olefin copolymer (X) is tetracyclododecene. 1 to 50% by mass of the propylene/cyclic olefin copolymer (X) according to claim 1 or 2, and 50 to 99% by mass of the base oil (B) [however, the mass of (X) and (B) % is calculated based on the total amount of (X) and (B) in the additive composition. ] Lubricating oil additive composition containing. A lubricating oil composition comprising the propylene/cyclic olefin copolymer (X) according to claim 1 or 2 and a lubricating base oil (B), wherein 100% by mass of the lubricating oil composition contains the propylene/cyclic A lubricating oil composition containing 0.01 to 30% by mass of an olefin copolymer (X). The lubricating oil composition according to claim 4, which contains an ashless dispersant other than the propylene/cyclic olefin copolymer (X) in an amount of 0 to 0.1% by mass based on 100% by mass of the lubricating oil composition. 6. The lubricating oil composition according to claim 4, wherein the pour point depressant (C) is contained in an amount of 0.05 to 5% by mass based on 100% by mass of the lubricating oil composition.