Lubricating oil additive, lubricating oil, and method for producing lubricating oil additive

Abstract

To provide a lubricating oil additive and a method for producing the same, and a lubricating oil, which are capable of simultaneously achieving the solubility, the shear stability and the viscosity index when added to an oil.SOLUTION: A lubricating oil additive comprises a polymer. The polymer comprises a structural unit (A) derived from a compound represented by the formula (1), and a structural unit (B) derived from a (meth)acryloyl group-containing compound. The content of the structural unit (A) is 21-99.9 mass%, the content of the structural unit (B) is 0.1-79 mass%, based on the total 100 mass% of all structural units. The weight-average molecular weight is 15,000-40,000. (R1 represents a group represented by CnH2n+m, n is an integer of 1-30, m is one of -3, -1 and 1, and 2n+m is an integer of 3 or more.)SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a lubricating oil additive, a lubricating oil, and a method for producing a lubricating oil additive.

Background Art

[0002] Conventionally, lubricating oils have been used in internal combustion engines, automatic transmissions, and other mechanical devices to smooth their operation. In recent years, from the perspective of global environmental protection, the fuel-saving performance required of lubricating oils has been increasing, and further improvement of the viscosity index, which is one of the indicators, has been demanded.

[0003] Patent Document 1 discloses using a copolymer composed of a structural unit derived from a conjugated diene and a structural unit derived from an aromatic vinyl compound as a viscosity index improver for lubricating oils. Patent Document 2 discloses using a copolymer of an alkyl (meth) acrylate as a lubricating oil additive such as a viscosity index improver.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the viscosity index improver disclosed in Patent Document 1 has a problem that when the content of the structural unit derived from the aromatic vinyl compound is large, the solubility in oil decreases. In addition, the copolymer disclosed in Patent Document 2 is excellent in the effect of improving the viscosity index of lubricating oils, but uses a petroleum-derived monomer as a raw material, which does not meet the recent social demands. In Patent Documents 1 and 2, the shear stability and viscosity index when a lubricating oil additive is added to oil have not been studied for compatibility.

[0006] An object of the present invention is to provide a lubricating oil additive that has excellent solubility when added to oil and can achieve both excellent shear stability and viscosity index, a lubricating oil using the lubricating oil additive, and a method for producing the lubricating oil additive.

Means for Solving the Problems

[0007] The present invention has the following aspects. [1] A lubricating oil additive containing a polymer, The polymer contains a structural unit derived from a compound represented by the following general formula (1) and a structural unit derived from a (meth)acryloyl group-containing compound. The content of the structural unit derived from the compound represented by the following general formula (1) in the total 100% by mass of all structural units is 21 to 99.9% by mass, and the content of the structural unit derived from the (meth)acryloyl group-containing compound is 0.1 to 79% by mass, and the weight average molecular weight is 15,000 to 40,000. Lubricating oil additive.

Chemical formula

Chemical formula

Advantages of the Invention

[0008] According to the present invention, there are provided a lubricating oil additive excellent in solubility when added to oil and capable of achieving both excellent shear stability and viscosity index, a lubricating oil using the lubricating oil additive, and a method for producing the lubricating oil additive.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be specifically described. However, the present invention is not limited to the following embodiments and can be variously modified and implemented within the scope of the gist thereof. In the present specification and claims, a numerical range represented by "~" means a numerical range including the numerical values before and after "~" as the lower limit value and the upper limit value. For example, A~B is synonymous with A or more and B or less. In the present invention, the "structural unit" means a unit constituting a polymer derived from a monomer, that is, a structural unit formed by polymerization of a monomer, or a structural unit in which a part of the structural unit is converted into another structure by subjecting the polymer to a modification treatment. The "(meth)acryloyl group" is a general term for the "acryloyl group" and the "methacryloyl group", and the same applies to "(meth)acrylate" and "(meth)acrylic". In the present specification, the "weight average molecular weight" and the "number average molecular weight" respectively mean the weight average molecular weight or the number average molecular weight in terms of standard polystyrene measured by the gel permeation chromatography (GPC) method.

[0010] [Lubricating oil additive] "First aspect" The lubricating oil additive of the first aspect of the present invention contains the following structural unit (A) and structural unit (B), and the content of the structural unit (A) in the total 100% by mass of all the structural units is 21 to 99.9% by mass, and the content of the structural unit (B) is 0.1 to 79% by mass, and a polymer having a weight average molecular weight of 15,000 to 40,000 (hereinafter, also referred to as "polymer (X1)"). The polymer (X1) may further contain, as necessary, a structural unit other than the structural unit (A) and the structural unit (B) (hereinafter, also referred to as "structural unit (C)") within a range not impairing the effects of the present invention, in addition to the structural unit (A) and the structural unit (B).

[0011] [Structural unit (A)] The structural unit (A) is a structural unit derived from a compound represented by the following general formula (1) (hereinafter, also referred to as "compound (A)"). The constituent unit (A) is preferably derived from a monomer obtained from a plant. That is, the compound (A) is preferably a monomer derived from a plant. The fact that it is a monomer derived from a plant can be confirmed by measuring the radioactive carbon concentration.

[0012]

Chemical formula

[0013] In the general formula (1), R 1 is a group represented by C n H 2n+m , n is an integer from 1 to 30, m is any one of -3, -1, and 1, and 2n + m is an integer of 3 or more.

[0014] n is an integer from 1 to 30, preferably an integer from 2 to 11, more preferably an integer from 6 to 11, still more preferably an integer from 6 to 10, particularly preferably an integer from 6 to 8, and most preferably 6. If n is below the above upper limit, it exhibits excellent solubility in oil. m is any one of -3, -1, and 1, preferably -3 or -1, and more preferably -1. 2n + m is an integer of 3 or more, preferably an integer from 3 to 61, more preferably an integer from 3 to 21, still more preferably an integer from 3 to 19, particularly preferably 11 to 19, and most preferably 11.

[0015] In particular, n is preferably an integer from 2 to 11 and m is -3 or -1. In this case, 2n + m is preferably an integer from 3 to 21, and more preferably an integer from 3 to 19. Among them, particularly, n is preferably an integer from 6 to 11 and m is -3 or -1. More preferably, n is an integer from 6 to 10 and m is -1. Still more preferably, n is an integer from 6 to 8 and m is -1. Particularly preferably, n is 6 and m is -1. R 1 As, a group represented by C6H 11 , a group represented by C6H 13 , C 11 H19 a group represented by, C 11 H 21 a group represented by, C 11 H 23 a group represented by is preferable, and C6H 11 a group represented by, C 11 H 19 a group represented by is more preferable, and C6H 11 a group represented by is even more preferable. R 1 is a group represented by C6H 11 in the case of, examples of compound (A) include myrcene. R 1 is C 11 H 19 in the case of a group represented by, examples of compound (A) include β-farnesene.

[0016] As the structural unit (A), a structural unit derived from at least one of myrcene and β-farnesene is preferable, and from the viewpoint of raw material price, a structural unit derived from myrcene (hereinafter, also referred to as "structural unit (A1)") is more preferable. Both myrcene and β-farnesene are available as plant-derived monomers, which is preferable from the viewpoint of constructing a carbon recycling society. The polymer (X1) may contain only one type of structural unit (A) or may contain two or more types of structural units (A).

[0017] The content of the structural unit (A) is preferably 21 to 99.9% by mass, more preferably 40 to 99.5% by mass, even more preferably 60 to 99.5% by mass, particularly preferably 80 to 99.5% by mass, and most preferably 90 to 99% by mass with respect to the total mass of all the structural units constituting the polymer (X1). If the content of the structural unit (A) is at least the above lower limit value, the solubility in oil, that is, the ability to dissolve in oil, is further improved. In addition, the polymer (X1) is less likely to gel. If the content of the structural unit (A) is at most the above upper limit value, the ability to improve the viscosity index is further enhanced. Incidentally, the content of the constitutional unit (A) can be determined by calculation from the charged amount of the compound (A), which is a monomer for introducing the constitutional unit (A), as a raw material monomer of the polymer (X1).

[0018] <Constitutional unit (B)> The constitutional unit (B) is a constitutional unit derived from a (meth)acryloyl group-containing compound (hereinafter also referred to as "compound (B)"). When the polymer (X1) contains the constitutional unit (B), the ability to improve the viscosity index is enhanced.

[0019] The compound (B) has a (meth)acryloyl group in the molecule. The compound (B) may be a monofunctional monomer having one (meth)acryloyl group or a polyfunctional monomer having two or more (meth)acryloyl groups. Among them, since it is easy to balance excellent shear stability and viscosity index, it is preferably a monofunctional monomer having one (meth)acryloyl group.

[0020] The number of carbon atoms of the compound (B) is preferably 3 to 65, more preferably 4 to 62, and even more preferably 4 to 60. If the number of carbon atoms of the compound (B) is at least the above lower limit, the ability to reduce friction is further improved. If the number of carbon atoms of the compound (B) is at most the above upper limit, the solubility in oil, that is, the solubility in oil, is further improved.

[0021] Examples of the compound (B) having one (meth)acryloyl group in the molecule include linear or branched alkyl group-containing (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, i-pentyl (meth)acrylate, 2-methylbutyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate; alicyclic (meth)acrylates such as cyclohexyl (meth)acrylate, 4-t-butylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentadienyl (meth)acrylate, dicyclopentanyl (meth)acrylate; hydroxy group-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 1,2-dihydroxyethyl (meth)acrylate, 1,2-dihydroxypropyl (meth)acrylate, 1,2-dihydroxybutyl (meth)acrylate, 1,2-dihydroxy-5-ethylhexyl (meth)acrylate, 1,1-dihydroxyethyl (meth)acrylate, 1,1-dihydroxypropyl (meth)acrylate, 1,1-dihydroxybutyl (meth)acrylate, 1,2,3-trihydroxypropyl (meth)acrylate, 1,2,3-trihydroxybutyl (meth)acrylate, 1,1,2-trihydroxypropyl (meth)acrylate, 1,1,2-trihydroxybutyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate;Epoxy group-containing (meth)acrylates such as glycidyl (meth)acrylate, glycidyl α-ethylacrylate, 3,4-epoxybutyl (meth)acrylate; amino group-containing (meth)acrylates such as dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate; (meth)acrylamide, N-t-butyl (meth)acrylamide, N-methylol (meth)acrylamide, N-isopropylacrylamide, hydroxyethylacrylamide, N-methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, diacetoneacrylamide and other amide group-containing (meth)acrylates, etc. can be mentioned.;

[0022] Examples of the compound (B) having two or more (meth)acryloyl groups include bifunctional monomers having two (meth)acryloyl groups, trifunctional monomers having three (meth)acryloyl groups, and tetrafunctional or higher monomers having four or more (meth)acryloyl groups.;

[0023] Examples of the bifunctional monomer include compounds represented by the following general formula (2).; CH2=CR 2 -COO-(R 3 O) p -COCR 4 =CH2···(2) (In the general formula (2), R 2 and R 4 are each independently a hydrogen atom or a methyl group, R 3 is an alkylene group having 1 to 10 carbon atoms, and p is an integer of 1 or more.)

[0024] R 3 is an alkylene group having 1 to 10 carbon atoms, preferably an alkylene group having 1 to 8 carbon atoms, more preferably an alkylene group having 1 to 6 carbon atoms, and even more preferably an alkylene group having 2 to 4 carbon atoms.; p is an integer of 1 or more, preferably 1 to 30, more preferably 1 to 20, even more preferably 1 to 16, particularly preferably 1 to 14, and most preferably 1 to 12.; When p is 2 or more, a plurality of R3 O may be the same or different.

[0025] Examples of the compound represented by the general formula (2) include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6 - hexanediol di(meth)acrylate, 1,5 - pentanediol di(meth)acrylate, 1,3 - butanediol di(meth)acrylate, polybutylene glycol di(meth)acrylate, and the like.

[0026] Examples of the trifunctional monomer include pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, and the like. Examples of the monomer having four or more functional groups include dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, ditrimethylolpropane tetraacrylate, tetramethylolmethane tetra(meth)acrylate, and the like.

[0027] As the compound (B), a compound having one (meth)acryloyl group in the molecule is preferable, and among them, a hydroxy - containing (meth)acrylate is particularly preferable, and 4 - hydroxybutyl (meth)acrylate and polypropylene glycol mono(meth)acrylate are more preferable. That is, as the structural unit (B), a structural unit derived from a (meth)acrylate having one (meth)acryloyl group and a hydroxy group in the molecule is preferable.

[0028] Among the compounds (B) having two or more (meth)acryloyl groups, the compound represented by the general formula (2) is preferred, 1,3-butanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and polypropylene glycol di(meth)acrylate are more preferred, and 1,3-butanediol di(meth)acrylate is even more preferred. The polymer (X1) may contain only one type of structural unit (B) or may contain two or more types of structural units (B).

[0029] The content of the structural unit (B) is 0.1 to 79% by mass based on the total mass of all the structural units constituting the polymer (X1), preferably 0.5 to 60% by mass, more preferably 0.5 to 40% by mass, even more preferably 0.5 to 20% by mass, and particularly preferably 1 to 10% by mass. When the content of the structural unit (B) is at least the lower limit value, the ability to improve the viscosity index is enhanced. When the content of the structural unit (B) is at most the upper limit value, the solubility in oil, that is, the solubility in oil, is improved. In addition, the polymer (X1) is less likely to gel. The content of the structural unit (B) can be determined by calculation from the charged amount of the compound (B), which is a monomer for introducing the structural unit (B), as a raw material monomer of the polymer (X1).

[0030] <Structural unit (C)> The structural unit (C) is a structural unit other than the structural units (A) and (B). That is, the structural unit (C) is a structural unit derived from a compound other than the compound (A) and the compound (B) (hereinafter also referred to as "compound (C)").

[0031] The compound (C) is not particularly limited as long as it is copolymerizable with at least one of the compound (A) and the compound (B). Examples of the compound (C) include vinyl cyanide monomers such as acrylonitrile and methacrylonitrile; aromatic vinyl monomers such as styrene, α-methylstyrene, and α-ethylstyrene; vinyl ether monomers such as vinyl methyl ether and vinyl ethyl ether; vinyl carboxylic acid monomers such as vinyl acetate and vinyl butyrate; olefin monomers such as ethylene, propylene, and isobutylene; vinyl halide monomers such as vinyl chloride and vinylidene chloride; maleimide monomers such as maleimide, N-phenylmaleimide, N-cyclohexylmaleimide, and N-methylmaleimide, and the like. The polymer (X1) may contain only one type of constituent unit (C) or may contain two or more types of constituent units (C).

[0032] The content of the constituent unit (C) is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less, and particularly preferably 8% by mass or less, based on the total mass of all the constituent units constituting the polymer (X1). If the content of the constituent unit (C) is at or below the above upper limit value, the solubility in oil, i.e., the oil solubility, is further improved. The content of the constituent unit (C) can be determined by calculation from the charged amount of the compound (C), which is a monomer for introducing the constituent unit (C), as a raw material monomer of the polymer (X1).

[0033] <Physical properties of the polymer (X1)> The weight average molecular weight of the polymer (X1) is from 15,000 to 40,000, preferably from 18,000 to 35,000, and more preferably from 20,000 to 30,000. If the weight average molecular weight of the polymer (X1) is at or above the above lower limit value, the ability to improve the viscosity index is enhanced. If the weight average molecular weight of the polymer (X1) is at or below the above upper limit value, the solubility in oil, i.e., the oil solubility, is improved, and the shear stability is further improved.

[0034] The number average molecular weight of the polymer (X1) is preferably from 5,000 to 40,000, more preferably from 8,000 to 30,000, and even more preferably from 10,000 to 25,000. If the weight average molecular weight of the polymer (X1) is at least the above lower limit, the ability to improve the viscosity index is further enhanced. If the weight average molecular weight of the polymer (X1) is at most the above upper limit, the solubility in oil, i.e., the ability to dissolve in oil, is further improved, and the shear stability is further improved.

[0035] <Method for producing polymer (X1)> The polymer (X1) can be obtained by polymerizing a compound (A), a compound (B), and, if necessary, a compound (C). The polymerization method is not particularly limited, and known methods can be employed. Examples include solution polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, etc. Among these, from the viewpoint of compatibility with lubricant additives, solution polymerization is preferred. That is, it is preferable to produce the polymer (X1) in a solvent. The polymer (X1) obtained by the solution polymerization method is obtained in the state of a polymer solution dissolved in a solvent. Hereinafter, an example of a method for producing the polymer (X1) by the solution polymerization method will be described in detail.

[0036] The polymer (X1) can be produced by polymerizing a monomer mixture (M1) containing a compound (A) and a compound (B) in a solvent by a known solution polymerization method. The monomer mixture (M1) may contain a compound (C) if necessary.

[0037] The content of the compound (A) is preferably 21 to 99.9% by mass, more preferably 40 to 99.5% by mass, even more preferably 60 to 99.5% by mass, particularly preferably 80 to 99.5% by mass, and most preferably 90 to 99% by mass based on the total mass of the monomer mixture (M1). The content of the compound (B) is 0.1 to 79% by mass, preferably 0.5 to 60% by mass, more preferably 0.5 to 40% by mass, even more preferably 0.5 to 20% by mass, and particularly preferably 1 to 10% by mass based on the total mass of the monomer mixture (M1). The content of the compound (C) is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less, and particularly preferably 8% by mass or less based on the total mass of the monomer mixture (M1).

[0038] As the solvent, known polymerization solvents can be used, but from the viewpoint of compatibility with lubricant additives, it is preferable to use base oils (base stocks) such as paraffinic oils, naphthenic oils, and aromatic oils. When using a base oil as the solvent in the production of the polymer (X1), the polymer (X1) produced in the base oil and the base oil can be used as lubricant additives. Examples of the base oil include mineral base oils refined from crude oil and synthetic oils chemically synthesized. Commercially available products can be used as the base oil, such as API Group III base oils like YUBASE3 manufactured by SK Lubricants Co., Ltd., base oils like API Group III plus such as YUBASE4 manufactured by SK Lubricants Co., Ltd., and polyalphaolefins like the product named "DURASYN170" manufactured by INEOS Oligomers. The solvent may be used alone or in combination of two or more.

[0039] It is preferable to use a radical polymerization initiator for the polymerization of the monomer mixture (M1). Examples of the radical polymerization initiator include organic peroxides such as t-butyl peroxypivalate, o-methylbenzoyl peroxide, bis-3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, cyclohexanone peroxide, benzoyl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, lauroyl peroxide, diisopropylbenzene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl peroxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate; and azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile). Among these, organic peroxides are preferred, and among them, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate is particularly preferred. The radical polymerization initiator may be used alone or in combination of two or more.

[0040] The polymerization temperature is preferably 40 to 150 °C, more preferably 80 to 130 °C. The polymerization time is preferably 1 to 24 hours, more preferably 5 to 15 hours.

[0041] <Solvent> The lubricant additive of the first aspect may contain a solvent. Examples of the solvent contained in the lubricant additive include base oils such as paraffinic oils, naphthenic oils, and aromatic oils. Examples of the base oil include the base oils exemplified in the description of the method for producing the polymer (X1). The solvent may be used alone or in combination of two or more.

[0042] The content of the solvent is preferably 0.1 to 99.9% by mass, more preferably 10 to 99% by mass, and even more preferably 30 to 98% by mass with respect to the total mass of the lubricating oil additive. If the content of the solvent is not less than the above lower limit value, a significant thickening of the lubricating oil can be suppressed. If the content of the solvent is not more than the above upper limit value, the ability to improve the viscosity index is further enhanced.

[0043] <Optional component> The lubricating oil additive of the first aspect may further contain, if necessary, components other than the polymer (X1) and the solvent (hereinafter also referred to as "optional components") within a range that does not impair the effects of the present invention, in addition to the polymer (X1) and the solvent. Examples of the optional components include detergents, dispersants, antioxidants, oiliness improvers, friction and wear modifiers, extreme pressure agents, defoamers, demulsifiers, corrosion inhibitors, pour point depressants, rust inhibitors, emulsifiers, fungicides, etc. The optional components may be used alone or in combination of two or more.

[0044] <Use> The lubricating oil additive of the first aspect is suitable as a lubricating oil additive to be added to various lubricating oils such as engine oil, gear oil, hydraulic oil, drive system lubricating oil, and automatic transmission oil used in mobility such as industrial machines, robots, and automobiles. The lubricating oil additive of the first aspect is particularly suitable as a viscosity index improver for lubricating oils.

[0045] For the viscosity index improver, the greater the degree of increase in kinematic viscosity due to the addition at high temperature and the smaller it is at low temperature, the better. Generally, it is known that a viscosity index improver composed of a (meth)acrylate polymer forms a fine particle structure without completely dissolving at low temperatures, and as the temperature rises, the solubility improves, the polymer chains expand, and the above-mentioned functions are exhibited. As an index of the performance of the viscosity index improver, a viscosity index calculated from the kinematic viscosities at low temperature (for example, 40°C) and high temperature (for example, 100°C) is used.

[0046] The viscosity index is a value measured in accordance with JIS K 2283:2000. The larger the numerical value, the smaller the viscosity change due to temperature. In recent years, for viscosity index improvers, higher values are also required for the viscosity (HTHS 150°C viscosity) under high temperature (150°C) and high shear conditions. Therefore, it is preferable that it does not completely dissolve at 100°C and the viscosity improvement effect can be expected even at higher temperatures. The dissolution state at 100°C can be evaluated, for example, by small-angle X-ray scattering measurement (SAXS).

[0047] The lubricating oil additive of the first aspect is excellent in the ability to improve the viscosity index. Specifically, the viscosity index measured by the method described in the examples below is likely to be 140 to 250. The viscosity index is more preferably 150 to 200. If the viscosity index is within the above range, the fuel consumption of vehicles and the like can be reduced.

[0048] <Manufacturing method> The manufacturing method of the first lubricating oil additive includes a step of manufacturing the polymer (X1). The first lubricating oil additive can be obtained, for example, by mixing the polymer (X1) with at least one of a solvent and optional components used as required. For example, when the polymer (X1) is manufactured by the solution polymerization method using base oil as a solvent, since the polymer (X1) manufactured in the solvent can be used as a lubricating oil additive together with the solvent, it is preferable to obtain the lubricating oil additive by manufacturing the polymer (X1) in the solvent. That is, the manufacturing method of the lubricating oil additive preferably includes a step of manufacturing the polymer (X1) in the solvent. In addition, the polymer solution in which the polymer (X1) is dissolved obtained by the solution polymerization method may be used as it is as a lubricating oil additive, or the polymer solution may be further diluted with a solvent as required to be used as a lubricating oil additive.

[0049] 「Second aspect」 The lubricant additive of the second aspect of the present invention contains a structural unit (A1) and a structural unit (B) described below, and the content of the structural unit (A1) in the total 100% by mass of all the structural units is 21 to 99.9% by mass, the content of the structural unit (B) is 0.1 to 79% by mass, and a polymer having a weight average molecular weight of 15,000 to 40,000 (hereinafter, also referred to as "polymer (X2)"). The polymer (X2) may further contain a structural unit (C) in addition to the structural unit (A1) and the structural unit (B), if necessary, as long as the effects of the present invention are not impaired.

[0050] <Structural unit (A1)> The structural unit (A1) is a structural unit derived from myrcene. Myrcene is available as a plant-derived monomer and is preferable from the viewpoint of constructing a carbon recycling society. The fact that it is a plant-derived monomer can be confirmed by measuring the radiocarbon concentration.

[0051] The content of the structural unit (A1) is preferably 21 to 99.9% by mass, more preferably 40 to 99.5% by mass, still more preferably 60 to 99.5% by mass, particularly preferably 80 to 99.5% by mass, and most preferably 90 to 99% by mass with respect to the total mass of all the structural units constituting the polymer (X2). If the content of the structural unit (A1) is at least the above lower limit value, the solubility in oil, that is, the ability to dissolve in oil is further improved. In addition, the polymer (X2) is less likely to gel. If the content of the structural unit (A1) is at most the above upper limit value, the ability to improve the viscosity index is further enhanced. The content of the structural unit (A1) can be determined by calculation from the charged amount of myrcene, which is a monomer for introducing the structural unit (A1), as a raw material monomer of the polymer (X2).

[0052] <Structural unit (B)> The structural unit (B) is a structural unit derived from the compound (B). By the polymer (X2) containing the structural unit (B), the ability to improve the viscosity index is enhanced. Examples of the compound (B) include the compounds (B) exemplified above in the description of the polymer (X1) of the first aspect. The polymer (X2) may contain only one type of structural unit (B) or may contain two or more types of structural units (B).

[0053] The content of the structural unit (B) is 0.1 to 79% by mass, preferably 0.5 to 60% by mass, more preferably 0.5 to 40% by mass, still more preferably 0.5 to 20% by mass, and particularly preferably 1 to 10% by mass, based on the total mass of all the structural units constituting the polymer (X2). When the content of the structural unit (B) is at least the lower limit value, the ability to improve the viscosity index increases. When the content of the structural unit (B) is at most the upper limit value, the solubility in oil, i.e., the ability to dissolve in oil, is improved. In addition, the polymer (X2) is less likely to gel. The content of the structural unit (B) can be determined by calculation from the charged amount of the compound (B), which is a monomer for introducing the structural unit (B), as a raw material monomer of the polymer (X2).

[0054] <Structural unit (C)> The structural unit (C) is a structural unit other than the structural unit (A1) and the structural unit (B). That is, the structural unit (C) is a structural unit derived from a compound other than myrcene and the compound (B). Examples of the compound other than myrcene and the compound (B) include the compounds (C) exemplified above in the description of the polymer (X1) of the first aspect. The polymer (X2) may contain only one type of structural unit (C) or may contain two or more types of structural units (C).

[0055] The content of the structural unit (C) is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less, and particularly preferably 8% by mass or less, based on the total mass of all the structural units constituting the polymer (X2). When the content of the structural unit (C) is at most the upper limit value, the solubility in oil, i.e., the ability to dissolve in oil, is further improved. The content of the structural unit (C) can be determined by calculation from the charged amount of the compound (C), which is a monomer for introducing the structural unit (C), as a raw material monomer of the polymer (X2).

[0056] <Physical properties> The weight average molecular weight of the polymer (X2) is from 15,000 to 40,000, preferably from 18,000 to 35,000, and more preferably from 20,000 to 30,000. If the weight average molecular weight of the polymer (X2) is at least the above lower limit, the ability to improve the viscosity index is enhanced. If the weight average molecular weight of the polymer (X2) is at most the above upper limit, the solubility in oil, i.e., the ability to dissolve in oil, is improved.

[0057] The number average molecular weight of the polymer (X2) is preferably from 5,000 to 40,000, more preferably from 8,000 to 30,000, and even more preferably from 10,000 to 25,000. If the weight average molecular weight of the polymer (X2) is at least the above lower limit, the ability to improve the viscosity index is further enhanced. If the weight average molecular weight of the polymer (X2) is at most the above upper limit, the solubility in oil, i.e., the ability to dissolve in oil, is further improved, and the shear stability is improved.

[0058] <Method for producing the polymer (X2)> The polymer (X2) can be obtained by polymerizing myrcene, the compound (B), and optionally the compound (C). The polymerization method is not particularly limited, but it is preferably produced by the same method as the polymer (X1). That is, the polymer (X2) is preferably produced by polymerizing a monomer mixture (M2) containing myrcene and the compound (B) in a solvent by a known solution polymerization method. The monomer mixture (M2) may contain the compound (C) as required.

[0059] The content of myrcene is preferably from 21 to 99.9% by mass, more preferably from 40 to 99.5% by mass, even more preferably from 60 to 99.5% by mass, particularly preferably from 80 to 99.5% by mass, and most preferably from 90 to 99% by mass based on the total mass of the monomer mixture (M2). The content of compound (B) is 0.1 to 79% by mass, preferably 0.5 to 60% by mass, more preferably 0.5 to 40% by mass, still more preferably 0.5 to 20% by mass, and particularly preferably 1 to 10% by mass based on the total mass of the monomer mixture (M2). The content of compound (C) is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less, and particularly preferably 8% by mass or less based on the total mass of the monomer mixture (M2).

[0060] When producing the polymer (X2) by solution polymerization, examples of the solvent and radical polymerization initiator used in the polymerization include the solvents and radical polymerization initiators exemplified above in the description of the polymer (X1) of the first aspect. Also, the polymerization temperature and polymerization time are the same as those in the case of producing the polymer (X1).

[0061] <Solvent> The lubricant additive of the second aspect may contain a solvent. Examples of the solvent contained in the lubricant additive include base oils such as paraffinic oils, naphthenic oils, and aromatic oils. Examples of the base oil include the base oils exemplified in the description of the production method of the polymer (X1). The solvent may be used alone or in combination of two or more.

[0062] The content of the solvent is preferably 0.1 to 99.9% by mass, more preferably 10 to 99% by mass, and still more preferably 30 to 98% by mass based on the total mass of the lubricant additive. If the content of the solvent is at least the above lower limit, significant thickening of the lubricating oil can be suppressed. If the content of the solvent is at most the above upper limit, the viscosity index improvement ability is further enhanced.

[0063] <Optional component> The lubricant additive of the second aspect may further contain optional components other than the polymer (X2) and the solvent, if necessary, within a range not impairing the effects of the present invention, in addition to the polymer (X2) and the solvent. Examples of optional components include detergents, dispersants, antioxidants, oiliness improvers, friction and wear modifiers, extreme pressure agents, defoamers, demulsifiers, corrosion inhibitors, pour point depressants, rust inhibitors, emulsifiers, and fungicides. The optional components may be used individually or in combination of two or more.

[0064] <Use> The lubricant additive of the second aspect is suitable as a lubricant additive to be added to various lubricants such as engine oil, gear oil, hydraulic oil, drive system lubricating oil, and automatic transmission oil used in mobility applications such as industrial machines, robots, and automobiles. The lubricant additive of the second aspect is particularly suitable as a viscosity index improver for lubricants.

[0065] The lubricant additive of the second aspect is excellent in the ability to improve the viscosity index. Specifically, the viscosity index measured by the method described in the examples below is likely to be between 140 and 250. A viscosity index of 150 to 200 is more preferable. If the viscosity index is within the above range, the fuel consumption of vehicles and the like can be reduced.

[0066] <Manufacturing method> The manufacturing method of the second lubricant additive includes a step of manufacturing the polymer (X2). The second lubricant additive can be obtained, for example, by mixing the polymer (X2) with at least one of a solvent and optional components used as necessary. For example, when manufacturing the polymer (X2) by solution polymerization using base oil as a solvent, since the polymer (X2) produced in the solvent can be used as a lubricant additive together with the solvent, it is preferable to obtain the lubricant additive by manufacturing the polymer (X2) in the solvent. That is, the manufacturing method of the lubricant additive preferably includes a step of manufacturing the polymer (X2) in the solvent. Note that the polymer solution in which the polymer (X2) obtained by the solution polymerization method is dissolved in the solvent may be used as it is as the lubricant additive, or may be further diluted with a solvent as necessary to be used as the lubricant additive.

[0067] [Lubricating oil] The lubricating oil according to an example of an embodiment of the present invention contains any one of the lubricating oil additives of the present invention described above, that is, either the lubricating oil additive of the first aspect or the lubricating oil additive of the second aspect. The lubricating oil may further contain components other than the lubricating oil additive of the present invention (hereinafter also referred to as "optional components") as necessary, as long as the effects of the present invention are not impaired. Examples of the optional components include the optional components exemplified above in the description of the lubricating oil additive of the first aspect. The optional components may be used alone or in combination of two or more.

[0068] When the lubricating oil contains the lubricating oil additive of the first aspect, the content of the polymer (X1) contained in the lubricating oil is preferably 0.01 to 30% by mass, more preferably 0.05 to 25% by mass, and still more preferably 0.1 to 20% by mass based on the total mass of the lubricating oil. If the content of the polymer (X1) is at least the lower limit value, the viscosity index of the lubricating oil is improved. If the content of the polymer (X1) is at most the upper limit value, the kinematic viscosity of the lubricating oil at low temperature is suppressed and the fuel consumption is improved. The content of the polymer (X2) in the lubricating oil when the lubricating oil contains the lubricating oil additive of the second aspect is the same as the content of the polymer (X1).

[0069] The lubricating oil is suitable as various lubricating oils such as engine oil, gear oil, hydraulic oil, drive system lubricating oil, and automatic transmission oil used in mobility such as industrial machines, robots, and automobiles.

Examples

[0070] Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded, and various modifications are possible without departing from the gist of the present invention. The measurement and evaluation methods are shown below.

[0071] <Calculation of the content of constitutional units> The content of each constitutional unit in the polymer was calculated from the charged amount of the monomer. The content of the structural unit (A1) relative to the total mass of the polymer was calculated from the charged amount of the millicene corresponding to the compound (A). The content of the structural unit (B) relative to the total mass of the polymer was calculated from the charged amount of the compound (B) or its substitute. The content of the structural unit (C) relative to the total mass of the polymer was calculated from the charged amount of the compound (C).

[0072] <Measurement of weight-average molecular weight (Mw) and number-average molecular weight (Mn)> The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the polymer were determined as the molecular weights in terms of standard polystyrene by GPC (gel permeation chromatography). Specifically, after preparing a tetrahydrofuran solution of the polymer solution, it was injected into an apparatus equipped with the separation column shown below, and the molecular weight of the polymer was measured under the measurement conditions shown below, and the mass-average molecular weight (Mw) and number-average molecular weight (Mn) were calculated in terms of standard polystyrene. · Apparatus: Product name "HLC-8220" manufactured by Tosoh Corporation, · Separation column: Product name "TSK-GEL SUPER HM-H" manufactured by Tosoh Corporation, exclusion limit molecular weight = 4×10 8 )), inner diameter 6.0 mm, length 150 mm. · Detector: RI (differential refractometer), UV, · Eluent: Tetrahydrofuran (THF), · Flow rate: 0.600 ml / min, · Sample concentration: 0.02 g / 10 mL, · Column temperature: 40 °C.

[0073] <Evaluation of solubility> The transparency of the diluted solution obtained by further diluting the polymer solution with a diluent solvent (YUBASE4 (mineral-based oil of API standard Group III plus), manufactured by SK Lubricants Co., Ltd.) so that the polymer concentration became 5% by mass was visually confirmed, and the solubility of the polymer in the base oil was evaluated according to the following evaluation criteria. 〇: Transparent. ×: Opaque or insoluble matter is precipitated.

[0074] <Measurement of Viscosity Index (VI)> For the polymer solution, the kinematic viscosity at 40 °C (Vk40) and the kinematic viscosity at 100 °C (Vk100) were measured in accordance with JIS K 2283:2000. Using the obtained “Vk40” and “Vk100”, the viscosity index (VI) was calculated in accordance with JIS K 2283:2000. The viscosity index is a physical property value representing the temperature dependence of the viscosity of lubricating oil.

[0075] <Measurement of Shear Stability Index (SSI)> For the polymer solution, the kinematic viscosity at 40 °C (Vk40) and the kinematic viscosity at 100 °C (Vk100) were measured in accordance with JIS K 2283:2000. Then, in accordance with the ultrasonic shear stability JASO method (JASO M347), the sample was sheared for 60 minutes, and the kinematic viscosity at 40 °C (VK40) and the kinematic viscosity at 100 °C (VK100) were measured again. Taking the kinematic viscosity before the shear test as A, the kinematic viscosity after the test as B, and the kinematic viscosity of the base oil alone as C, the shear stability index (SSI) at 40 °C and 100 °C was calculated respectively from the following calculation formula. Shear Stability Index (SSI) = (A - B) / (A - C) × 100

[0076] <Measurement of Coefficient of Friction (COF)> The lubricating oil additive was applied onto a SUJ-2 disk with φ24 × 7.9 mm. Using a vibrating friction and wear tester (SRV tester) and a SUJ-2 ball with φ10 mm, under the conditions of a test temperature of 40 °C, an amplitude of 1 mm, and a frequency of 50 Hz, the load was 50 N for the first 30 seconds after the start of the test, and the load was changed to 200 N after 30 seconds. The coefficient of friction was measured, and the average value of the coefficient of friction measured during the test time of 50 - 60 minutes was obtained and taken as the COF.

[0077] [Example 1] 33 parts by mass of a lubricating oil base oil (manufactured by SK Lubricants Co., Ltd., trade name "YUBASE4"), 90 parts by mass of Mirsen (manufactured by Yasuhara Chemical Co., Ltd.), and 10 parts by mass of polypropylene glycol monomethacrylate (PP-800, manufactured by NOF Corporation) were charged into a dried Schlenk tube. After thoroughly replacing the inside of the Schlenk tube with nitrogen, the liquid temperature was raised to 100 °C. Next, 10.0 parts by mass of 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate (manufactured by NOF Corporation, trade name "Perocta O") was added as a radical polymerization initiator, and the reaction was carried out for 10 hours to obtain a polymer solution containing 77% by mass of the polymer, which was used as a lubricating oil additive. For the obtained polymer solution, the molecular weight, viscosity index, shear stability index, and friction coefficient of the polymer were measured. Also, the polymer solution was diluted with a diluting solvent, and the solubility was evaluated. The results are shown in Table 1.

[0078] [Examples 2 to 4, Comparative Examples 1 to 3] The amounts of Mirsen, compound (B) or its substitute, and compound (C) were changed so that the types and contents of the constitutional units (A1), (B), and (C) constituting the polymer would be the values shown in Table 1, and the amount of Perocta O added was changed to the value shown in Table 1. Otherwise, a polymer solution was produced in the same manner as in Example 1, and various measurements and evaluations were performed. The results are shown in Table 1.

[0079]

Table 1

[0080] The abbreviations in Table 1 are as follows. ·PP-800: Polypropylene glycol monomethacrylate (manufactured by NOF Corporation, compound (C)), ·SLMA: Alkyl methacrylate (manufactured by Mitsubishi Chemical Corporation, trade name: Acryester SL, carbon number of alkyl group: 12 - 13), ·1,3-BDMA: 1,3-Butanediol dimethacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.).

Industrial Applicability

[0081] The lubricant additive of the present invention is excellent in shear stability index, viscosity index improvement ability and solubility in oil, and is suitable as an additive to be added to various lubricating oils such as engine oil, gear oil, hydraulic oil, drive system lubricating oil, and automatic transmission oil used in mobility applications such as industrial machinery, robots, and automobiles.

Claims

1. A lubricating oil additive containing a polymer, wherein the polymer contains a structural unit derived from a compound represented by the following general formula (1) and a structural unit derived from a (meth)acryloyl group-containing compound, and the content of the structural unit derived from the compound represented by the following general formula (1) in the total 100% by mass of all structural units is 21 to 99.9% by mass, the content of the structural unit derived from the (meth)acryloyl group-containing compound is 0.1 to 79% by mass, and the weight average molecular weight is 15,000 to 40,000. A lubricating oil additive. 【Chemical 1】 (In the general formula (1), R １ is a group represented by C ｎ H ２ｎ＋ｍ , n is an integer from 1 to 30, m is either -3, -1, or 1, and 2n + m is an integer of 3 or more.)

2. In the general formula (1), n is an integer of 2 to 11, m is -3 or -1, and 2n + m is an integer of 3 to 19. The lubricating oil additive according to Claim 1.

3. In the general formula (1), n is an integer of 6 to 11, and m is -3 or -1. The lubricating oil additive according to Claim 2.

4. In the general formula (1), R １ is a group represented by C ６ H １１ The lubricating oil additive according to claim 3.

5. A lubricating oil additive containing a polymer, wherein the polymer contains a structural unit derived from myrcene and a structural unit derived from a (meth)acryloyl group-containing compound, and the content of the structural unit derived from myrcene in the total 100% by mass of all structural units is 21 to 99.9% by mass, and the content of the structural unit derived from the (meth)acryloyl group-containing compound is 0.1 to 79% by mass, and the weight average molecular weight is 15,000 to 40,000. A lubricating oil additive.

6. The carbon number of the (meth)acryloyl group-containing compound is 3 to 65. The lubricating oil additive according to any one of Claims 1 to 5.

7. A lubricating oil containing the lubricating oil additive according to any one of Claims 1 to 5.

8. A lubricating oil containing the lubricating oil additive according to Claim 6.

9. A method for producing a lubricating oil additive, including a step of producing a polymer, wherein the polymer contains a structural unit derived from a compound represented by the following general formula (1) and a structural unit derived from a (meth)acryloyl group-containing compound, and the content of the structural unit derived from the compound represented by the following general formula (1) in the total 100% by mass of all structural units is 21 to 99.9% by mass, the content of the structural unit derived from the (meth)acryloyl group-containing compound is 0.1 to 79% by mass, and the weight average molecular weight is 15,000 to 40,000. A method for producing a lubricating oil additive. 【Chemical 2】 (In general formula (1), R １ is a group represented by C ｎ H ２ｎ＋ｍ , n is an integer from 1 to 30, m is either -3, -1, or 1, and 2n + m is an integer of 3 or more.)

Images