JPH07286189A - Lubricating oil additive and lubricating oil - Google Patents

Abstract

PURPOSE:To obtain a lubricating oil additive comprising a polymer containing a specific alkyl (meth)acrylate and a compound such as N-vinylpyrrolidone in a specific ratio as constituting units, capable of being used even under severe environments, and excellent in low temperature viscosity characteristics and oxidation resistance. CONSTITUTION:This lubricating oil additive comprises (A) a polymer containing (i) 70-99.5wt.% of an alkyl (meth)acrylate wherein the alkyl has <=10 carbon atoms, and (ii) 0.5-30wt.% of one or more kinds of compounds selected from N-vinylpyrrolidone, an N,N-dialkylaminoalkyl (meth)acrylate wherein the alkyl has 1-4 carbon atoms, vinylpyridine, morpholinoethyl (meth)acrylate and vinylimidazole as constituting units, and further preferably (B) a pour point- depressant such as a chlorinated paraffin/naphthalene condensate. The compounding weight ratio of the components A/B is preferably 80/20 to 99/1.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to lubricating oil additives and lubricating oils. In particular, the present invention relates to a lubricating oil additive excellent in viscosity index improving ability, low temperature viscosity characteristic improving ability and oxidation resistance, and a lubricating oil to which the additive is added.

[0002]

BACKGROUND OF THE INVENTION It is known to add lubricating oil additives consisting of polyalkyl (meth) acrylates to lubricating oils. For example, US Pat. No. 2,628,225 discloses the addition of polyalkylmethacrylates to lubricating oils as viscosity index improvers. In addition, JP-A-47-1
Japanese Patent No. 2982 discloses a lubricating oil additive containing a copolymer having a constitutional unit composed of an alkyl acrylate and an alkyl methacrylate. Polyalkyl (meth) acrylates have been widely used due to their excellent viscosity index improving ability, low temperature viscosity characteristics, and pour point depressing ability. In addition, since the conventional polyalkyl (meth) acrylate attaches importance to the pour point depressing ability, the alkyl (meth) having 12 or more carbon atoms of the alkyl group is a constituent unit.
Alkyl methacrylate has been mainly used as a structural unit because it contains acrylate in an amount of 50% by weight or more and also has the same importance as pour point depressing ability. Also,
JP-B-49-42649 and JP-A-2-29681.
No. 1 discloses a viscosity index improver comprising a long-chain alkyl (meth) acrylate and a nitrogen-containing polar monomer such as N-vinylpyrrolidone, but its antioxidant property and clean dispersibility are not satisfactory. Absent.

[0003]

In order to comply with the recent tightening of CAFE regulations and the newly set lubricating oil standards in response to them, especially lubricating oils for passenger cars have low-temperature viscosity characteristics, anti-oxidation properties and clean dispersibility. There is a growing demand for improvements in However, conventional polyalkyl (meth) acrylates have been problematic in that they do not meet the requirements for improving low temperature viscosity characteristics, antioxidant properties and clean dispersibility.
In particular, gear oils and automatic transmission fluids are strongly required to have these performances.

[0004]

Means for Solving the Problems As a result of intensive studies on these problems, the present inventors have found that an alkyl (meth) acrylate having an alkyl group having a specific carbon number as a constitutional unit, N-vinylpyrrolidone, The viscosity of a lubricating oil additive made of a polymer containing an N, N-dialkylaminoalkyl (meth) acrylate having 1 to 4 carbon atoms in an alkyl group, vinylpyridine, morpholinoethyl (meth) acrylate, vinylimidazole, etc. It has been found that it has excellent index-improving ability and low-temperature viscosity characteristics as well as excellent antioxidative properties and clean dispersibility.

That is, according to the present invention, 70 to 99.5% by weight of an alkyl (meth) acrylate (a1) having an alkyl group having 10 or less carbon atoms, N-vinylpyrrolidone, and an alkyl group having 1 to 10 carbon atoms are contained as constituent units. 4, containing 0.5 to 30% by weight of one or more compounds (a2) selected from the group consisting of N, N-dialkylaminoalkyl (meth) acrylate, vinylpyridine, morpholinoethyl (meth) acrylate and vinylimidazole. A lubricating oil additive comprising the polymer (A), a mineral oil, a high viscosity index mineral oil containing isomerized paraffin, a hydrocarbon-based synthetic lubricating oil, an ester-based synthetic lubricating oil, and a mixture of two or more thereof. A lubricating oil obtained by adding the lubricating oil additive to a lubricating base oil (C) selected from

Examples of the alkyl (meth) acrylate (a1) having an alkyl group having 10 or less carbon atoms include:
Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth)
Acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate,
Decyl (meth) acrylate and the like can be mentioned, and the alkyl group may be a straight chain or one having a side chain.

Of these, alkyl (meth) acrylate monomers (a1-
Particularly preferred in 1) is the case where the alkyl group has 1 and / or 4 carbon atoms, and the preferred monomer (a1-2) having an alkyl group having 5 to 10 carbon atoms has 8 carbon atoms. It has an alkyl group of. Further, acrylates are preferable to methacrylates because the polymers based on them are less likely to undergo depolymerization and have excellent antioxidant properties. That is, examples of preferable monomers include methyl (meth) acrylate, n-, i- or t-butyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and the like. Particularly preferred are n-, i- or t-butyl acrylate, n-octyl acrylate and 2-ethylhexyl acrylate. Whether (a1-1) and (a1-2) are used in combination (a1-
Only 2) is preferred. That is, (a1-1) and (a1-2)
There is a preferred range for the weight ratio of
It is preferable when it is 30:70, especially 5:95 to 20 :.
80 is preferred. Within this range, the polymer (A) has both excellent low temperature viscosity characteristics and antioxidant properties.

Examples of (a2) include N-vinylpyrrolidone, N, N-dialkylaminoalkyl (meth) acrylates having an alkyl group having 1 to 4 carbon atoms {N, N-dimethylaminoethyl (meth) acrylate, N, From N-diethylaminoethyl (meth) acrylate, N, N-dipropylaminoethyl (meth) acrylate, N, N-dibutylaminoethyl (meth) acrylate, etc.}, vinylpyridine, morpholinoethyl (meth) acrylate, vinylimidazole One or more compounds selected from the group consisting of N-vinylpyrrolidone,
N, N-dimethylaminoethyl (meth) acrylate is preferred. The content of (a2) is 0.5 to 30% by weight of (A), preferably 1 to 15% by weight. 0.
If it is less than 5% by weight, the antioxidative property may be insufficient.
When it exceeds the weight%, there may be a problem in solubility in mineral oil.

(A) is a constitutional unit of (a1) and (a)
It may be a random copolymer containing 2) or a graft polymer composed of a trunk polymer containing (a1) as a constituent unit and a branch polymer containing (a2) as a constituent unit. good. Preferably, (a
1) and a graft polymer composed of a trunk polymer containing (a2) and a branch polymer containing (a2) or (a1) and (a2) as a constitutional unit. When it is composed (a2), a branch polymer is composed (a2).
Are particularly preferred. Further, it is more preferable that (a2) constituting the trunk polymer is N, N-dimethylaminoethyl (meth) acrylate and (a2) constituting the branch polymer is N-vinylpyrrolidone. The weight ratio of (a2) constituting the trunk polymer and (a2) constituting the branch polymer is preferably 1/1 to 1/20. If it deviates from this range, the antioxidant property may deteriorate.

In the present invention, the polymer (A), as a constituent unit, has a polymerizable double bond in addition to (a1) and (a2) within a range of less than 30% by weight, preferably less than 20% by weight. The other compound (a3) may be contained. Other compounds having a polymerizable double bond (a
Examples of 3) include alkyl (meth) acrylates having an alkyl group having 11 to 20 carbon atoms (dodecyl methacrylate, tetradecyl methacrylate, hexadecyl methacrylate, octadecyl methacrylate, acrylates having these alkyl groups, etc.); C1-C30 unsaturated monocarboxylic acid esters of alkyl groups (butyl crotonate, octyl crotonate, dodecyl crotonate, octyl crotonate, etc.); C1-C30 alkyl esters of unsaturated polycarboxylic acids (Dibutyl maleate, dioctyl maleate, dilauryl maleate, distearyl maleate, dioctyl fumarate, dilauryl fumarate, etc.); vinyl aromatic compounds (styrene, 4-methylstyrene, etc.), and the like. It can be used one or more kinds as (a3) of the.

Of these, preferred are those having 11 to 11 carbon atoms.
An alkyl (meth) acrylate monomer having 20 alkyl groups and styrene. It is preferable to use an alkyl (meth) acrylate monomer having an alkyl group having 11 to 20 carbon atoms as (a3) because excellent low temperature fluidity can be obtained without using a pour point depressant together. Monomer (a3)
Is 30% by weight or more of the constituent units of the polymer (A), problems may occur in the antioxidant property, low temperature viscosity property, and solubility in lubricating oil. The polymer (A) may be a random copolymer of the monomer (a3) and the monomers (a1) and (a2), or a trunk polymer composed of the monomer (a1). Monomer (a2) and (a
A graft polymer composed of the branch polymer of 3) may also be used.

The polymer (A) in the present invention can be produced by a known method. For example, a mixture of (a1), (a2) and optionally the above-mentioned monomer (a3) is polymerized with or without a solvent using a radical polymerization catalyst such as an azo type or a peroxide type. It can be manufactured by Further, a blend of (a1) and (a2) is polymerized by using a radical polymerization catalyst such as an azo type or a peroxide type to prepare a trunk polymer, and (a2) is further used a peroxide type radical polymerization catalyst. Then, it can be produced by graft polymerization. In order to control the molecular weight, a chain transfer agent (for example, mercaptans, (alkyl) anilines, phenols, alcohols, amines, etc.) can be used in combination for polymerization. As the solvent, a mineral oil, a hydrocarbon synthetic lubricating oil such as a dodecene oligomer, and an ester synthetic lubricating oil such as dioctyl adipate or an ester of trimethylolpropane and a fatty acid are preferable.

The weight average molecular weight of the polymer (A) in the present invention is usually 10,000 to 900,000, preferably 30,000 to 600,000. If the weight average molecular weight is less than 10,000, a sufficient thickening effect cannot be obtained. Further, if it exceeds 900,000, the shear stability is poor and may be a problem in practical use. The weight average molecular weight is a value measured by GPC and obtained using polystyrene as a calibration curve.

The lubricating oil additive of the present invention is usually a polymer (A).
Is a mineral oil, a high-viscosity index mineral oil containing isomerized paraffin obtained by hydrolyzing paraffin, a hydrocarbon-based synthetic lubricating oil, an ester-based synthetic lubricating oil, and a dilute solution in an oil selected from a mixture of two or more thereof. It is obtained as The concentration of the polymer (A) in the lubricating oil additive of the present invention is usually 30 to 80% by weight, preferably 40 to 70% by weight. If it is less than 30% by weight, sufficient thickening effect and viscosity index improving ability may not be exhibited, and if it exceeds 80% by weight, the viscosity of the additive becomes high and handling becomes difficult.

It is preferable that a pour point depressant (B) is further added to the lubricating oil additive of the present invention. As the pour point depressant (B), a usual alkylmethacrylate-based pour point depressant (for example, a polymer containing n-tetradecyl methacrylate as a main component) or a chlorinated paraffin / naphthalene condensate can be used. The compounding ratio of the polymer (A) and the pour point depressant (B) is preferably 80:20 to 99: 1.
(Weight ratio), particularly preferably 90:10 to 95: 5. If the amount of the pour point depressant exceeds 80:20, the thickening may be insufficient, or the polymer (A) and the pour point depressant may not be compatible with each other and may be separated, and if it is less than 99: 1. Pour point descent may be insufficient.

The lubricating oil additive of the present invention is used as the lubricating oil of the present invention by blending and dissolving it in the lubricating base oil (C) so as to have a desired viscosity. The mineral oil in (C) has a viscosity range of normal 50 neutral oil to 300 neutral oil, and as a specific example, normal mineral oil and paraffin are hydrogenated with a hydrogenation catalyst. High-viscosity index mineral oil containing decomposed isomerized paraffin; hydrocarbon-based synthetic lubricating oil such as hydrocarbon-based synthetic lubricating oil consisting of α-olefin oligomer; ester-based synthetic lubricating oil such as dioctyl adipate, fatty acid And esters of trimethylolpropane and the like, respectively. (C) may be a mixture of two or more of those exemplified above. In particular, an isomerized paraffin-containing high-viscosity index oil, which has excellent low-temperature viscosity characteristics, excellent antioxidative properties, and excellent economical efficiency, is preferably used alone, or a mixture containing 70% by weight or less of ordinary mineral oil. The lubricating oil additive of the present invention is usually added to the lubricating base oil (C) in an amount of 1 to 30% by weight and used as the lubricating oil of the present invention. When the lubricating oil of the present invention is an engine oil, 2 to 10% by weight, and in the case of a gear oil or an automatic transmission oil, 7 to 25% by weight gives a preferable result.

The lubricating oil of the present invention may contain other known additives. These known additives include viscosity index improvers {for example, known ones such as hydrogenated products of ethylene / propylene copolymers and styrene / isoprene copolymers, and further in these olefinic viscosity index improvers. A known clean dispersibility containing N atom,
Known poly (meth) acrylate-based viscosity index improvers, etc.}, extreme pressure additives, detergents, dispersants, antioxidants, friction reducing agents, pour point depressants and the like can be mentioned.

The intended applications of the lubricating oil of the present invention include gasoline engine oil, diesel engine oil, gear oil, automatic transmission oil, hydraulic oil, tractor oil, power steering oil, shock absorber oil, compressor oil and the like. .

[0019]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. In the examples, parts and% represent parts by weight and% by weight, respectively.

Example 1 A reactor equipped with a stirrer, a heating device, a thermometer, a nitrogen blowing tube, and a cooling tube was charged with 43 neutral 100 mineral oils.
0 part was charged, the atmosphere was replaced with nitrogen, and the temperature was raised to 85 ° C. n
-Butyl acrylate 95 parts, 2-ethylhexyl acrylate 855 parts, N, N-dimethylaminoethyl methacrylate 50 parts and azobisisobutyronitrile 10
Parts of the mixture were added dropwise continuously over 3 hours, and 1 more
After aging for a period of time, a copolymer solution having a weight average molecular weight of 50,000 and a concentration of 69% was obtained. To 93 parts of this solution, 7 parts of Acluve 133 (manufactured by Sanyo Kasei) as a polymethacrylate-based pour point depressant was blended to obtain an additive (1) of the present invention.

Example 2 A copolymer solution having a weight average molecular weight of 50,000 and a concentration of 68% was polymerized in the same manner as in Example 1 except that 95 parts of n-butyl acrylate was changed to 95 parts of methyl methacrylate. Got Acluve 132 (manufactured by Sanyo Kasei) as a polymethacrylate-based pour point depressant for 90 parts of this solution
Was blended in 10 parts to obtain the additive (2) of the present invention.

Example 3 Example 1 except that 50 parts of N, N-dimethylaminoethyl methacrylate was changed to 50 parts of N-vinylpyrrolidone.
Polymerization is carried out in the same manner as above, and the weight average molecular weight is 50,000.
A copolymer solution having a concentration of 69% was obtained. To 93 parts of this solution, 7 parts of Acluve 133 (manufactured by Sanyo Chemical Co., Ltd.) as a polymethacrylate-based pour point depressant was blended to obtain an additive (3) of the present invention.

Example 4 950 parts of 2-ethylhexyl acrylate, 25 parts of N, N-dimethylaminoethyl methacrylate and 25 parts of N-vinylpyrrolidone were polymerized in the same manner as in Example 1 to give a weight average molecular weight of 4.5. Then, a copolymer solution having a concentration of 69% was obtained. To 90 parts of this solution, 10 parts of Acluve 133 (manufactured by Sanyo Chemical Co., Ltd.) as a polymethacrylate-based pour point depressant was blended to obtain an additive (4) of the present invention.

Example 5 33 Neutral Oil of 100 Neutral was added to a reactor equipped with a stirrer, a heating device, a thermometer, a nitrogen blowing pipe, and a cooling pipe.
0 part was charged, the atmosphere was replaced with nitrogen, and the temperature was raised to 85 ° C. Two
A mixture of 970 parts of ethylhexyl acrylate and 5 parts of azobisisobutyronitrile was continuously added dropwise over 3 hours, followed by aging for 1 hour to obtain a trunk polymer solution. Furthermore, a solution prepared by dissolving 4 parts of t-butyl perbenzoate and 30 parts of N-vinylpyrrolidone in 100 parts of 100 neutralized hydrogenated oil was stirred at a temperature of 130 ° C.
Dropwise addition was carried out for 30 minutes, and then graft polymerization was carried out for 2 hours. A copolymer solution having a weight average molecular weight of 49,000 and a concentration of 69% was obtained. To 95 parts of this solution, 5 parts of Acluve 133 (manufactured by Sanyo Kasei) as a polymethacrylate-based pour point depressant was blended to obtain an additive (5) of the present invention.

Example 6 Polymerization was carried out in the same manner as in Example 5 except that 970 parts of 2-ethylhexyl acrylate was changed to 900 parts of decyl acrylate to obtain a trunk polymer. Furthermore, 50 parts of N-vinylpyrrolidone and 50 parts of n-butyl acrylate
Graft polymerization was carried out in the same manner as in Example 5 except that the mixture was changed to 100 parts of vinylpyrrolidone to obtain a copolymer solution having a weight average molecular weight of 48,000, a concentration of 68% by weight. 95 parts of this solution was mixed with 5 parts of Acluve 133 as a polymethacrylate-based pour point depressant to obtain an additive (6) of the present invention.

Example 7 The same method as in Example 5 except that 970 parts of 2-ethylhexyl acrylate were changed to 94 parts of n-butyl acrylate, 849 parts of 2-ethylhexyl acrylate and 7 parts of N, N-dimethylaminoethyl methacrylate. Polymerization was carried out to obtain a trunk polymer. Furthermore, a solution prepared by dissolving 4 parts of t-butylperbenzoate and 50 parts of N-vinylpyrrolidone in 100 parts of hydrorefined 100 neutral oil was added dropwise, and graft polymerization was carried out in the same manner as in Example 5. A copolymer solution having a weight average molecular weight of 53,000 and a concentration of 68% was obtained. To 93 parts of this solution, 7 parts of Acluve 133 was added as a polymethacrylate-based pour point depressant to obtain an additive (7) of the present invention.

Example 8 970 parts of 2-ethylhexyl acrylate, 145 parts of n-butyl acrylate, 567 parts of 2-ethylhexyl acrylate, 100 parts of n-dodecyl methacrylate,
Polymerization was carried out in the same manner as in Example 5 except that the mixture was changed to 55 parts of n-tetradecyl methacrylate, 15 parts of n-hexadecyl methacrylate, 8 parts of n-octadecyl methacrylate and 10 parts of N, N-dimethylaminoethyl methacrylate. Then, a trunk polymer was obtained. Further, 30 parts by weight of N-vinylpyrrolidone was replaced by a mixture of 50 parts by weight of 2-ethylhexyl acrylate and 50 parts by weight of N-vinylpyrrolidone to carry out graft polymerization in the same manner as in Example 5 to obtain a weight average molecular weight of 49,000, A copolymer solution having a concentration of 69% by weight was obtained. To 93 parts of this solution, 7 parts of Acluve 133 was added as a polymethacrylate-based pour point depressant to obtain an additive (8) of the present invention.

Example 9 In the same manner as in Example 5 except that 970 parts of 2-ethylhexyl acrylate was changed to a mixture of 85 parts of styrene, 765 parts of 2-ethylhexyl acrylate and 50 parts of N, N-dimethylaminoethyl methacrylate. Polymerization was performed to obtain a trunk polymer. Further, a solution prepared by dissolving 8 parts of t-butyl perbenzoate and 100 parts of N-vinylpyrrolidone in 100 parts of hydrorefined 100 neutral oil was added dropwise, and graft polymerization was carried out in the same manner as in Example 5. A copolymer solution having a weight average molecular weight of 51,000 and a concentration of 69% was obtained. To 93 parts of this solution, 7 parts of Acluve 133 was added as a polymethacrylate-based pour point depressant to obtain an additive (9) of the present invention.

Comparative Example 1 30 neutral mineral oil was added to a reactor equipped with a stirrer, a heating device, a thermometer, a nitrogen blowing pipe, and a cooling pipe.
0 part was charged, the atmosphere was replaced with nitrogen, and the temperature was raised to 85 ° C. n
-A mixture of 70 parts of butyl acrylate, 630 parts of 2-ethylhexyl acrylate and 7 parts of azobisisobutyronitrile was continuously added dropwise over 3 hours and aged for 1 hour, the weight average molecular weight was 50,000 and the concentration was 69%. A copolymer solution of Add 93 parts of this solution as a polymethacrylate type pour point depressant (manufactured by Sanyo Kasei)
Was mixed in an amount of 7 parts to obtain a comparative additive (ratio 1).

Comparative Example 2 110 parts of n-butyl acrylate, 320 parts of 2-ethylhexyl acrylate, 2 parts of n-dodecyl methacrylate 2
Using a mixture of 70 parts and 270 parts of n-tetradecyl methacrylate, polymerization was carried out in the same manner as in Example 5 to prepare a trunk polymer solution. Furthermore, t-butyl perbenzoate 8
Parts, 30 parts of N-vinylpyrrolidone were hydrorefined 1
A solution dissolved in 100 parts of 00 neutral oil was added dropwise, and graft polymerization was carried out in the same manner as in Example 5 to obtain a copolymer solution having a weight average molecular weight of 50,000 and a concentration of 69%. To 93 parts of this solution, 7 parts of Acluve 133 was added as a polymethacrylate-based pour point depressant to give a comparative additive (ratio 2).

Test Example Additives (1) to (9) of the present invention obtained in Examples 1 to 7 and comparative additives (Ratio 1) and (Ratio 2) obtained in Comparative Examples 1 and 2 were used, respectively. Table 1 shows the results of the low temperature viscosity test, the antioxidant test, and the carbon black dispersibility test conducted by the following methods. (Method of low temperature viscosity test) Additives (1) to (9), (ratio 1) and (ratio 2) were uniformly dissolved in 90 parts of mineral oil of 10 parts and 100 neutral, respectively. The low temperature viscosity test method for gear oils specified by the Japan Petroleum Institute (J
According to PI-5S-26-85), the low temperature viscosity was measured at -40 ° C.

(Method of Antioxidant Test) Additives (1) to (9), (ratio 1) to 90 parts of 100 neutral mineral oil.
10 parts of (and 2) are uniformly dissolved, and JIS-
According to K2514, an antioxidant test was performed at 165.5 ° C. for 98 hours, and the amount of sludge generated by the B method was measured. Here, the B method is a method in which a sludge flocculant is added to the lubricating oil after the test and the amount of sludge settled by centrifugal separation is measured,
The amount of sludge by method B shows antioxidant property.

(Carbon Black Dispersibility Test) 0.3 g of carbon black was placed in a sample container (JISK2839) for the anti-emulsification test, and the additives (1) to (9) of Examples 1 to 9 were added to 60 neutral mineral oil. And a solution containing 3% by weight each of the additives of Comparative Examples 1 and 2 (ratio 1) and (ratio 2) were added to make the total liquid volume 80 ml. Anti-emulsification tester (JISK2520) at 30 ° C, 1500
After stirring at rpm for 5 minutes, 75 ml was placed in a 100 ml centrifugal sedimentation tube and centrifuged at 2000 rpm for 20 minutes,
The supernatant was diluted 1/60 with 60 neutral mineral oil and the absorbance at a wavelength of 750 nm was measured. The larger the absorbance, the better the dispersibility, the smaller the amount of sludge generated by oxidation, and the more the correlation with the clean dispersibility. The results are shown in Table 1. It can be seen that the additives of the examples have much better dispersibility than the additives of the comparative examples, that is, they have excellent antioxidant properties and clean dispersibility.

[0034]

Table 1 Additives Viscosity at -40 ° C Sludge amount Absorbance (cSt) (%) ---------------------------------------------------------------------------------------------------------- --- (1) 39000 1.2 0.56 (2) 45000 1.0 0.60 (3) 40000 1.1 0.59 (4) 42000 0.9 0.67 (5) 41000 0.6 0.70 (6) 43000 0.6 0.71 (7) 38000 0.5 0.75 (8) 46000 0.9 0.69 (9) 51000 1.0 0.66 -------- −−−−−−−−−−−−−−−−−−−−−−−−−− (Ratio 1) 40000 1.6 0.02 (Ratio 2) 75000 2.4 0.45 −− −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−

[0035]

INDUSTRIAL APPLICABILITY The lubricating oil additive of the present invention has excellent low temperature viscosity characteristics and oxidation resistance characteristics as compared with conventional methacrylate polymer type viscosity index improvers. Therefore, the lubricating oil of the present invention using the additive of the present invention has excellent flow characteristics at low temperatures and oxidation stability at high temperatures, and can be used even in harsh environments.

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Claims (15)

[Claims] 1. An alkyl (meth) acrylate (a1) having an alkyl group having 10 or less carbon atoms as a constituent unit.
70 to 99.5% by weight, N-vinylpyrrolidone, N, N-dialkylaminoalkyl (meth) acrylate having 1 to 4 carbon atoms in the alkyl group, vinylpyridine, morpholinoethyl (meth) acrylate, vinylimidazole One or more compounds (a2) selected from the group
A lubricating oil additive comprising the polymer (A) containing 5 to 30% by weight. 2. The additive according to claim 1, wherein (a1) is an alkyl acrylate having an alkyl group having 10 or less carbon atoms. 3. (a1) is an alkyl (meth) acrylate monomer having an alkyl group having 1 to 4 carbon atoms (a1-
The additive according to claim 1, which is a combination of (1) and an alkyl (meth) acrylate (a1-2) having an alkyl group having 5 to 10 carbon atoms or only (a1-2). 4. (a1) has 1 and / or 4 carbon atoms
The additive according to claim 3, which comprises an alkyl acrylate having an alkyl group of 1 and an alkyl acrylate having an alkyl group having 8 carbon atoms. 5. The additive according to claim 3, wherein the weight ratio of (a1-1) to (a1-2) is 0: 100 to 30:70. 6. A trunk polymer in which (A) contains (a1) or (a1) and (a2) as a structural unit,
(A1) and (a2), or (a
The lubricating oil additive according to any one of claims 1 to 5, which is a graft polymer composed of a branch polymer containing 2). 7. The lubricating oil additive according to claim 6, wherein (a2) which constitutes the trunk polymer and (a2) which constitutes the branched polymer are different compounds. 8. (A) is a trunk polymer containing (a1) as a constituent unit and N, N-dimethylaminoethyl (meth) acrylate, and N-vinylpyrrolidone or (a1) and N as a constituent unit. The lubricating oil additive according to claim 7, which is a graft polymer composed of a branch polymer containing vinylpyrrolidone. 9. The weight ratio of N, N-dimethylaminoethyl methacrylate to N-vinylpyrrolidone is 1/1 to 1
Lubricating oil additive according to claim 8 which is / 20. 10. The additive according to claim 1, which contains less than 30% by weight of an alkyl (meth) acrylate monomer (a3) having a C11-20 alkyl group as a constituent unit. 11. The additive according to claim 1, which further contains a pour point depressant (B). 12. The weight ratio of (A) and (B) is 80:20.
The additive according to claim 11, which is ˜99: 1. 13. The additive according to claim 1, which is for gear oil, automatic transmission oil, power steering oil or shock absorber oil. 14. A lubricating base oil (C) selected from mineral oil, high viscosity index mineral oil containing isomerized paraffin, hydrocarbon synthetic lubricating oil, ester synthetic lubricating oil and a mixture of two or more thereof. A lubricating oil obtained by adding the lubricating oil additive according to any one of claims 1 to 13. 15. Gear oil, automatic transmission oil, power steering oil or shock absorber oil comprising the lubricating oil according to claim 14.