JPH08183988A - New viscosity index improving agent and lubricating oil - Google Patents

Abstract

PURPOSE: To obtain the improving agent consisting of an alkylacrylate-based polymer and an alkylmethacylate-based polymer each having an alkyl group of a specific carbon number, excellent in viscosity index improving capabilities, low temperature viscosity and oxidation resisting characteristics, and fuel saving properties. CONSTITUTION: This viscosity index improving agent comprises consisting of (A) an alkylacrylate-based polymer and (B) an alkylmethacrylate-based polymer each having a 1-20C alkyl group. It is preferable to blend 20-80wt.% component (A) and 80-20wt.% component (B). Furthermore, as the alkylacrylate constituting the component (A) or the alkylmethacrylate constituting the component (B), n-octyl (meth) acrylate or 2-ethylhexyl (meth) acrylate alone or the alkyl (meth) acrylate consisting of the monomer having the 8C alkyl group, ethyl (meth) acrylate and/or n-, i- or t-butyl (meth) acrylate are preferred. Furthermore, it is preferable to blend a pour point depressant to the above improving agent.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to viscosity index improvers and lubricating oils. In particular, the present invention relates to a viscosity index improver excellent in viscosity index improving ability, low temperature viscosity characteristics and oxidation resistance characteristics, and fuel economy, and a lubricating oil to which the agent is added.

[0002]

It is known to add viscosity index improvers consisting of polyalkyl (meth) acrylates to lubricating oils. For example, US Pat. No. 2,628,225 discloses the addition of polyalkylmethacrylates to lubricating oils. Further, JP-A-47-12982 discloses a viscosity index improver 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. Also,
Since the conventional polyalkyl (meth) acrylate attaches importance to the pour point depressing ability, it contains 50% by weight or more of an alkyl (meth) acrylate having 12 or more carbon atoms in the alkyl group as a structural unit, and also has the same pour point. Alkyl methacrylate has been mainly used as a constitutional unit from the viewpoint that importance is attached to the descending ability. For lubricating oil and hydraulic oil,
Due to social demands for fuel efficiency in recent years, low temperature viscosity has been strongly desired. As one of the means to solve this, use of high viscosity index oil containing isomerized paraffin, synthetic lubricating oil, MLDW oil, etc. is becoming popular, and these are used alone or in combination with ordinary solvent refined mineral oil and the like. Has started to take place. In particular, the use of high viscosity index oil is becoming widespread in terms of performance and economy. Attempts have been made to lower the low temperature viscosity by using a pour point depressant in combination with this high viscosity index oil. An example of this is found in JP-A-54-70305, but
There is a demand for a viscosity index improver suitable for the present high viscosity index oil. Further, as a solution for enhancing fuel economy, a molybdenum-based friction and wear reducing agent (FM agent) has come to be used.

[0003]

In order to comply with the recent tightening of CAFE regulations and the newly set lubricating oil standards in response to the regulations, passenger vehicle lubricating oils, in particular, have low-temperature viscosity characteristics, oxidation resistance, and fuel efficiency. There is a growing demand for improvements in However, the conventional polyalkyl (meth) acrylate has a problem that low-temperature viscosity characteristics and oxidation resistance are insufficient to meet the demand for improvement. In particular, engine oil, gear oil, and automatic transmission oil are strongly required to have these performances. In addition, conventional polyalkyl (meth) acrylate-based viscosity index improvers have insufficient solubility and low-temperature viscosity characteristics, as well as sufficient antioxidant and heat resistance properties for high viscosity index oils and synthetic lubricating oils. Therefore, it is hard to say that the good heat resistance and antioxidative performance of these base oils can be sufficiently brought out. Especially for high viscosity index oils, it is difficult to say that conventional viscosity index improvers have sufficient low temperature viscosity characteristics. Further, it is difficult to say that the conventional lubricating oils containing the viscosity index improver and the FM agent have a significant increase in the friction coefficient when subjected to oxidative deterioration and the friction and wear reducing effect is sufficiently exerted.

[0004]

Means for Solving the Problems As a result of intensive studies on these problems, the present inventors have found that an alkyl acrylate polymer (PAA) and an alkyl methacrylate polymer (PMA) having an alkyl group having a specific carbon number. It has been found that the viscosity index improver consisting of (1) and (4) is excellent in viscosity index improving ability, low temperature viscosity characteristics, fuel economy, and also has excellent oxidation resistance, and can sufficiently exert the effect of the FM agent.

That is, the present invention relates to an alkyl acrylate polymer (PA having an alkyl group having 1 to 20 carbon atoms).
A) and a viscosity index improver comprising an alkyl methacrylate polymer (PMA) having an alkyl group having 1 to 20 carbon atoms; and mineral oil, MLDW oil, high viscosity index mineral oil containing isomerized paraffin, carbonization Hydrogen-based synthetic lubricating oil,
A lubricating oil obtained by adding the above viscosity index improver to a lubricating base oil (D) selected from ester synthetic lubricating oils and mixtures of two or more thereof. Further, it is a lubricating oil containing the viscosity index improver and the FM agent.

Examples of the alkyl (meth) acrylate monomer having an alkyl group having 1 to 20 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, dodecyl (meth) acrylate, tetradecyl ( Examples thereof include (meth) acrylate, hexadecyl (meth) acrylate, and octadecyl (meth) acrylate. The alkyl group of these monomers may be linear or have a side chain.

Of these various monomers, the alkyl (meth) acrylate monomer (A-1) or (B-1) having an alkyl group having 1 to 4 carbon atoms is particularly preferable. A monomer having 1 and / or 4 carbon atoms and having an alkyl group having 5 to 10 carbon atoms (A-
2) or (B-2) is preferable to have an alkyl group having 8 carbon atoms. However, the carbon number of the alkyl group is 5
In the case of the alkyl acrylate of No. 7, when it is used as a base oil such as a high viscosity index oil containing isomerized paraffin or a synthetic lubricating oil of an oligomer of alpha olefin, it may be unusable due to poor solubility. . 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. Among them, methyl (meth) acrylate is particularly preferable,
n-, i- or t-butyl (meth) acrylate,
Mention may be made of n-octyl (meth) acrylate and 2-ethylhexyl (meth) acrylate. (A-1)
And (A-2) are preferably used together or only (A-2) is preferred.
That is, there is a preferred range for the weight ratio of (A-1) and (A-2), which is preferred when the ratio is 0: 100 to 30:70, and particularly preferred when it is 5:95 to 20:80.
Further, (B-1) and (B-2) are preferable when used in combination. In this case, the ratio of (B-1) and (B-2) is 5: 9.
It is preferable when it is 5 to 30:70, and particularly 10:90 to
It is preferable when it is 25:75. In these ranges, the improver of the present invention has excellent low temperature viscosity characteristics and oxidation resistance, excellent solubility in high viscosity index oils and synthetic lubricating oils, and the effect of sufficiently exerting the effects of FM agents. .

The improving agent of the present invention comprises the above-mentioned alkyl acrylate polymer (PAA) having an alkyl group and alkyl methacrylate polymer (PMA), and the amount of (PAA) is usually 35% by weight or less. , Preferably 5 to 30% by weight, more preferably 10 to 25% by weight, of an alkyl acrylate-based polymer obtained by copolymerizing the above-mentioned alkyl methacrylate monomer having an alkyl group, and / or usually as (PMA). The use of an alkyl methacrylate-based polymer obtained by copolymerizing 35% by weight or less, preferably 5 to 30% by weight, more preferably 10 to 25% by weight of the above-mentioned alkyl acrylate monomer having an alkyl group provides a better low temperature viscosity. It exhibits characteristics and is preferable. Most preferred are an alkyl acrylate polymer (PAA) obtained by copolymerizing 10 to 25 wt% of an alkyl methacrylate monomer and an alkyl methacrylate polymer (PMA) obtained by copolymerizing 10 to 25 wt% of an alkyl acrylate monomer. It consists of

The viscosity index improver of the present invention comprises an alkyl acrylate polymer (PAA) having an alkyl group having 20 or less carbon atoms and an alkyl methacrylate polymer (PM).
A) and, but (PAA) and (PMA)
In addition, it may be a polymer containing one or more kinds of monomers having one or more kinds of atoms selected from nitrogen atom, oxygen atom and sulfur atom, if necessary. Examples of the introduction method include random copolymerization, graft copolymerization, and graft addition. In this case, it is preferable that the improver of the present invention can be imparted with detergent dispersibility and antioxidant, and particularly, if the detergent dispersibility and the antioxidant can be imparted simultaneously, the antioxidant of the enhancer of the present invention can be improved. A synergistic effect with the effect of being excellent is excellent in heat resistance, which is preferable. Examples of imparting this clean dispersibility and antioxidative property include USP501346, USP501347.
0, EP508012, USP4606834, USP
4036766, USP4036768, USP490
4404, USP 4812261, USP 466841
2, USP 4790948, USP 47955577, JP-A-60-110790, JP-A-61-247719,
JP-A-63-51497, JP-A-63-179999,
Japanese Patent Laid-Open Nos. 01-193308 and 01-28459
3, JP-A-62-141096, JP-A-02-2968
11, JP-A-04-211498, JP-A-06-158
Those described in 075 etc. can be used. Examples of those which impart clean dispersibility by random copolymerization or graft copolymerization include N-vinylpyrrolidone, N-vinylthiopyrrolidone, vinylpyridine, N, N-dialkylaminoalkylene (meth) acrylate (of an alkyl group). The carbon number is usually 1 to 4), N, N-dialkylaminoalkylene (meth) acrylamide (the carbon number of the alkyl group is usually 1 to 4), vinylimidazole, morpholinoalkylene (meth) acrylate and the like can be mentioned. In addition, examples of those capable of simultaneously imparting clean dispersibility and antioxidant by similar copolymerization include aminophenothiazine and N-
Arylphenylenediamine, aminocarbazole, aminothiazole, aminoindole, aminopyrrole,
Examples include various compounds such as aminoimidazoline, aminomercaptothiazole, and (meth) acrylate derivatives having an aminopiperidine residue. As an example of the compound to be graft-added, a small amount of carboxylic acid compound (maleic anhydride, methacrylic acid, crotonic acid, itaconic acid, etc.) (for example, 0.5 to 5 wt. %) Copolymerized and amidated or imidized with (poly) amine, or Mannich condensed with formaldehyde and (poly) amine. Furthermore, a non-vinyl compound (for example, phenothiazines, imidazoles, thiazoles, benzothiazoles, triazoles, thiazolinedins, pyrimidines, piperazines, pyrrolidinones, Examples thereof include those to which oxazoles, thiomorpholines and the like) have been graft-added. The amount of these various compounds in (PAA) and (PMA) is usually 20% by weight or less, preferably 10% by weight or less, and particularly preferably 5% by weight or less.

In the present invention, (PAA), (PMA)
As a constituent unit, other monomer (E) having a polymerizable double bond can be contained in the range of less than 30% by weight, preferably less than 20% by weight. Examples of the other monomer (E) having a polymerizable double bond include unsaturated monocarboxylic acid esters having an alkyl group having 1 to 30 carbon atoms (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.); Examples thereof include nitrile group-containing compounds (acrylonitrile, methacrylonitrile, etc.); vinyl aromatic compounds (styrene, 4-methylstyrene, etc.), and one or more of these monomers can be used as (E). When a hydroxyl group-containing (meth) acrylate as an alkyl group is copolymerized, the effect of the FM agent may not be sufficiently exhibited.

Of these, preferred are acrylonitrile and styrene. When the acrylonitrile monomer is used, the one having a high viscosity index is obtained, and when the styrene monomer is used, the thickening effect is excellent. When the monomer (E) exceeds 30% by weight of the constituent units of (PAA) and (PMA), problems may occur in oxidation resistance, low temperature viscosity characteristics, and solubility in lubricating oil. The effect of the FM agent may not be fully exerted. In addition, (P
AA) or (PMA) may be a random copolymer of the monomer (E) and the monomer (A) or (B), and may also be a monomer with the backbone polymer chain of (PAA) or (PMA). It may be a graft polymer with a side chain formed by the body (E).

(PAA) and (PMA) in the present invention can be produced by a known method. For example, polymerizing an alkyl (meth) acrylate monomer with or without a solvent, and optionally a blend of the above-mentioned monomer (E), using a radical polymerization catalyst such as an azo type or a peroxide type. It can be produced by using a chain transfer agent (for example, mercaptans, (alkyl) anilines, phenols, alcohols, amines, etc.) to control the molecular weight. Can be obtained. The solvent is preferably a mineral oil, a hydrocarbon synthetic lubricating oil such as a decene oligomer, or an ester synthetic lubricating oil such as dioctyl adipate or an ester of trimethylolpropane and a fatty acid.

The weight average molecular weight of (PAA) and (PMA) 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 viscosity index improver of the present invention is usually (PAA)
Or (PMA) is a mineral oil, a high-viscosity index mineral oil containing isomerized paraffin obtained by hydrolyzing paraffin, a hydrocarbon synthetic lubricating oil, an ester synthetic lubricating oil, and an oil selected from a mixture of two or more thereof. It is obtained as diluted and dissolved in a class. (PAA) and (PM of the present invention
The concentration of A) 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 ability to improve viscosity index may not be exhibited.
If it exceeds 0% by weight, the viscosity of the improver becomes high and handling becomes difficult.

It is preferable to add a pour point depressant (C) to the viscosity index improver of the present invention. As the pour point depressant (C), an ordinary 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. Further, these methacrylate-based compounds having a combination of two or more kinds having different compositions and molecular weights (for example, those described in JP-A-54-70305), and those having a very high molecular weight (for example, USP5229021) and the like. The ratio of (C) is usually (PAA) and (PMA)
When the total weight is 100 parts by weight, the amount is in the range of 1 to 20 parts by weight. If it is less than 1 part, the pour point lowering action may be insufficient, and if it exceeds 20 parts by weight, the thickening may be insufficient.

The viscosity index improver of the present invention is blended and dissolved in the lubricating base oil (D) so as to have a desired viscosity and used as the lubricating oil of the present invention. The base oil (D) is usually one having a viscosity range of 50 neutral oil to 300 neutral oil. Specific examples include ordinary mineral oils. Further, as the viscosity index improver of the present invention to be added and used, synthetic lubricating oil (hydrocarbon type such as decene oligomer, alcohol such as trimethylolpropane, pentaerythritol, hexamethylenediol and fatty acid Examples thereof include esters and ester-based compounds represented by esters of adipic acid and aliphatic alcohols. Further, it is produced by a process called mobil lube dewaxing, and specific examples thereof include MLDW oil in which wax is decomposed and removed by a synthetic zeolite catalyst or the like. In particular, the viscosity index improver of the present invention is most effective in high viscosity index oils. This differs greatly from ordinary mineral oils in terms of performance and composition. This high-viscosity index oil is disclosed in Dutch Patent Application No. 7613854 and JP-A-5-21434.
It is manufactured by the method described in 9 or the like. That is,
It contains a component obtained by hydrolyzing n-paraffin using a catalyst to isomerize it into i-paraffin. As the hydrocracking catalyst at this time, a synthetic zeolite, a noble metal catalyst or the like is usually used. In addition, the i manufactured in this way
-A paraffin-containing isomerized mineral oil further purified by solvent is also included in the present invention. Since such an isomerized paraffin-containing mineral oil has a composition greatly different from that of a usual solvent-refined mineral oil, it has a large viscosity index and is usually about 110 to 160 although it varies depending on the production method and the i-paraffin content. (Ordinary mineral oil has a viscosity index of about 90 to 105). Further, the oil of high viscosity index has an excellent antioxidant property because the content of aromatic compounds is extremely small. Therefore, a lubricating oil that essentially contains the high viscosity index oil is preferred. The improver of the present invention is usually added to these lubricating base oils (D) in an amount of 0.3 to 30% by weight and used as the lubricating oil of the present invention. When the lubricating oil of the present invention is engine oil, it is 1 to 10% by weight, and when it is gear oil or automatic transmission oil, it is 7%.
It gives favorable results when added at .about.25% by weight.
When the lubricating oil of the present invention is produced, (PAA) and (PMA) and, if necessary, the pour point depressant (C) are separately added to the lubricating base oil (D) and blended. Such cases are also included in the present invention.

The viscosity index improver of the present invention is also characterized in that when it is used in combination with a molybdenum FM agent, its effect can be maximized. Examples of the FM agent include thiophosphate-based agents and carbamate-based agents. Specifically, Japanese Patent Publications 44-29366 and 49
-6362, JP-B-51-964, JP-B-53-316
46, JP-B-55-40593, JP-B-55-4059
3, Japanese Patent Publication No. 3-32596, Japanese Patent Publication No. 6-33390, Japanese Patent Publication No. 6-47675, and the like. It is not clear why the viscosity index improver of the present invention exhibits excellent FM properties when used in combination with an FM agent, in other words, excellent fuel economy. When the viscosity index improver of the present invention is used, it may be possible to form a complex with a different FM agent and change the decomposition rate of the FM agent as compared with the case of using the conventional one. The ratio of these FM agents in lubricating oil is usually 0.05.
˜5% by weight, the improver is 0.3 to 30% by weight, and the lubricating base oil (D) is 99.65 to 65% by weight. FM
If the content of the agent is less than 0.05%, there is almost no effect of reducing frictional wear, and if it exceeds 5% by weight, the effect of reducing frictional wear is almost the same as when it is less than 5% by weight, which is economically disadvantageous.

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 (sulfur / phosphorus-based products sold under the trademark Angramol of Lubrizol, sulfur-based compounds represented by sulfurized olefins, etc.) , Detergents (sulfonate, salicylate, naphthenate, etc. calcium, magnesium overbased salts, etc.), dispersants (polyisobutenyl succinimide, Mannich condensation products of alkylphenols and polyamines, these Modified products with boric acid), antioxidants (zinc dithiophosphate, zinc dithiocarbamate, hindered phenols, hindered amines, alkyldiphenylamines, etc.), oiliness agents (fatty acid esters, fatty acid amides, etc.), rust inhibitors (alkyl succinates) Acid esters, alkylbenzene and alkylnaphtha Sulfonate-based, such as down, etc.), and the like frictional wear preventing agent (of the phosphorus-based typified by phosphoric acid ester and phosphite etc., etc.).

Applications of the improver and lubricating oil of the present invention are gasoline engine oil, diesel engine oil, gear oil, automatic transmission oil, hydraulic oil, tractor oil, power steering oil, shock absorber oil, compressor oil, etc. Is mentioned.

[0020]

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.

Synthesis Example 1 100 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

Synthesis Example 2 Polymerization was carried out in the same manner as in Synthesis Example 1 except that 630 parts of 2-ethylhexyl acrylate was changed to 630 parts of decyl acrylate, the weight average molecular weight was 510,000, and the concentration was 6
An 8% copolymer solution was obtained.

Synthesis Example 3 Polymerization was carried out in the same manner as in Synthesis Example 1 except that 70 parts of n-butyl methacrylate and 630 parts of 2-ethylhexyl methacrylate were used, and the weight average molecular weight was 470000 and the concentration was 69%. A copolymer solution was obtained.

Synthesis Example 4 Polymerization was carried out in the same manner as in Synthesis Example 1 except that 70 parts of n-butyl methacrylate and 630 parts of decyl methacrylate were used, and a copolymer solution having a weight average molecular weight of 50,000 and a concentration of 69%. Got

Synthesis Example 5 Polymerization was carried out in the same manner as in Synthesis Example 1 except that 70 parts of methyl methacrylate, 560 parts of 2-ethylhexyl acrylate and 70 parts of lauryl methacrylate were used, and the weight average molecular weight was 49,000 and the concentration was 70. % Polymer solution was obtained.

Synthesis Example 6 Polymerization was carried out in the same manner as in Synthesis Example 1 except that 70 parts of n-butyl acrylate, 70 parts of 2-ethylhexyl acrylate and 560 parts of decyl methacrylate were used, and the weight average molecular weight was 49,000. A polymer solution having a concentration of 69% was obtained.

Synthesis Example 7 Polymerization was carried out in the same manner as in Synthesis Example 1 except that 0.5 part of azobisvaleronitrile was used as the polymerization catalyst instead of 7 parts of azobisisobutyronitrile, and the weight average molecular weight was 188,000. A copolymer solution having a concentration of 69% was obtained.

Synthesis Example 8 Polymerization was carried out in the same manner as in Synthesis Example 3 except that 0.5 part of azobisvaleronitrile was used as the polymerization catalyst instead of 7 parts of azobisisobutyronitrile, and the weight average molecular weight was 197,000. A copolymer solution having a concentration of 69% was obtained.

Synthesis Example 9 Polymerization was carried out in the same manner as in Synthesis Example 1 except that 140 parts of methyl methacrylate, 280 parts of dodecyl methacrylate, 210 parts of tetradecyl methacrylate, and 70 parts of hexadecyl methacrylate were used, and the weight average molecular weight was 46,000. so,
A copolymer solution having a concentration of 68% was obtained.

Synthesis Example 10 Except that 0.5 part of azobisvaleronitrile was used instead of 7 parts of azobisisobutyronitrile as a polymerization catalyst.
Polymerized in the same manner as in Synthesis Example 9 to give a weight average molecular weight of 188,000,
A copolymer having a concentration of 69% was obtained.

Examples 1 to 3 At a temperature of 80 ° C., the copolymer solution of Synthesis Example 1 and the copolymer solution of Synthesis Example 3 and a pour point depressant were blended in the proportions shown in Table 1 to Examples 1 to 3. The viscosity index improver of the present invention was obtained. still,
ACLUVE 138 is a pour point depressant manufactured by Sanyo Kasei Co., Ltd.

[0032]

[Table 1]

Examples 4 to 6 At a temperature of 80 ° C., the copolymer solution of Synthesis Example 2 and the copolymer solution of Synthesis Example 4 and the pour point depressant were blended in the proportions shown in Table 2 to Examples 4 to 6. The viscosity index improver of the present invention was obtained. still,
ACLUVE 133 is a pour point depressant manufactured by Sanyo Kasei Co., Ltd.

[0034]

[Table 2]

Examples 7 to 9 At a temperature of 80 ° C., the copolymer solution of Synthesis Example 5 and the copolymer solution of Synthesis Example 6 and the pour point depressant were mixed in the proportions shown in Table 3 to Examples 7 to 9. The viscosity index improver of the present invention was obtained. still,
Acluve 132 is a pour point depressant manufactured by Sanyo Kasei Co., Ltd.

[0036]

[Table 3]

Examples 10 to 11 At a temperature of 80 ° C., the copolymer solution of Synthesis Example 7 and the copolymer solution of Synthesis Example 8 and a pour point depressant were blended in the proportions shown in Table 4 to improve the present invention. Got

[0038]

[Table 4]

Comparative Example 1 In the same manner as in Example 1, the copolymer solution 95 of Synthesis Example 3 was prepared.
Parts and 5 parts of Acluve 138 to make a comparative improver.

Comparative Example 2 The copolymer solution 95 of Synthesis Example 4 was prepared in the same manner as in Example 1.
Parts and 5 parts of Acluve 133 to make a comparative improver.

Comparative Example 3 The copolymer solution 95 of Synthesis Example 8 was prepared in the same manner as in Example 1.
Parts and 5 parts of Acluve 138 to make a comparative improver.

Comparative Example 4 The compound of Synthesis Example 9 was used as a comparative improver as it was.

Comparative Example 5 The compound of Synthesis Example 10 was used as it was as a comparative improver.

EXAMPLES Use Examples 1 to 9 and Comparative Use Examples 1 to 100 100 neutral high viscosity index oils having a viscosity index of 131 or normal 100 neutral mineral oils were used in Examples 1 to 9 and Comparative Examples 1 and 2 and Comparative Example 4. 1 for each viscosity index improver
Add 2 to 13% and mix evenly to obtain a 100 ° C viscosity of 7.4 to 7.6c required for auto match transmission oil.
Adjusted to St. Using this adjusted oil, the low temperature viscosity test method (JPI-5S-26) specified by the Japan Petroleum Institute is used.
According to -85), the viscosity at -40 ° C was measured and the results shown in Table 5 were obtained.

[0045]

[Table 5]

As is apparent from Table 5, the improver of the present invention gives a low temperature viscosity to ordinary mineral oils.
Especially when it is used for high viscosity index oil, the effect is remarkable and it gives a very low viscosity at low temperature.

Examples of Use 10 to 12 and Comparative Example of Use 4
~ 6 According to JIS-K2514, using the compounded oils of Working Examples 1 to 3 and the compounded oils of Comparative Use Examples 1 to 165.5.
An oxidation resistance test was performed at 98 ° C. for 98 hours, the amount of sludge was measured by the B method, and the results shown in Table 6 were obtained. Here, the B method is a method in which a sludge coagulant is added to the lubricating oil after the test, and the amount of sludge precipitated by centrifugal separation is measured. The smaller the amount, the better the oxidation resistance.

[0048]

[Table 6]

Working Examples 13 to 15 and Comparative Example 7
-8% of the improving agent of the present invention or a comparative improving agent of 3.9% each, molybdenum dithiophosphate-based FM agent (Sunflick F
M-2, Sanyo Kasei Co., Ltd.) 1%, engine oil package additive (for SG standard oil) 10%, high viscosity index oil with viscosity index 131 or ordinary solvent refined mineral oil 85.1 each. % Blended to achieve 100 ° C viscosity required for engine oil 1
Adjusted to 0.0-10.4 cSt. These blended oils were subjected to an antioxidant test for 48 hours according to JIS-K2514 under a temperature condition of 165.5 ° C. These samples after oxidative deterioration were subjected to a friction and wear tester of SRV at a temperature of 50 ° C.
The friction coefficient was measured under the conditions of a load of 50 Newtons and a frequency of 50 Hz, and the results shown in Table 7 were obtained.

[0050]

[Table 7]

Working Examples 16-18 and Comparative Example 9
-10 The friction coefficient was measured in the same manner as in Use Examples 10 to 12 and Comparative Use Examples 7 to 8 except that a molybdenum dithiocarbamate type agent (Morivan A, manufactured by Vanderbilt) was used as the FM agent. I got the result.

[0052]

[Table 8]

[0053]

INDUSTRIAL APPLICABILITY The viscosity index improver of the present invention has excellent low temperature viscosity characteristics and oxidation resistance characteristics as compared with conventional methacrylate polymer type viscosity index improvers. It gives a very low -40 ° C viscosity, especially when used in high viscosity index oils. or,
When used in combination with a molybdenum-based friction and wear inhibitor, it has a characteristic of giving a low friction coefficient even if it is subjected to oxidative deterioration. Therefore, the lubricating oil of the present invention using the improver of the present invention is excellent in flow characteristics at low temperatures and oxidation stability at high temperatures, can be used in harsh environments, and has excellent fuel economy. Becomes

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Claims (17)

[Claims] 1. An alkyl acrylate polymer (PAA) having an alkyl group having 1 to 20 carbon atoms, and 1 to 1 carbon atoms.
A viscosity index improver comprising an alkyl methacrylate polymer (PMA) having 20 alkyl groups. 2. (PAA) 20 to 80% by weight, (PM
The improver according to claim 1, wherein A) is 80 to 20% by weight. 3. (PAA) has 1 carbon atom as a constitutional unit.
The improver according to claim 1 or 2, which is a polymer containing 70% by weight or more of an alkyl acrylate monomer (A) having 0 or less alkyl groups. 4. (A) is an alkyl acrylate monomer (A-1) having an alkyl group having 1 to 4 carbon atoms and an alkyl acrylate monomer (A-2) having an alkyl group having 5 to 10 carbon atoms. 4.) The improving agent according to claim 3, which is used in combination with (1) or only (A-2). 5. (A-1) is an alkyl acrylate having an alkyl group having 1 and / or 4 carbon atoms, and (A-1)
The improver according to claim 4, wherein -2) is an alkyl acrylate having an alkyl group having 8 carbon atoms. 6. The improver according to claim 4, wherein the weight ratio of (A-1) to (A-2) is 0: 100 to 30:70. 7. (PMA) has 1 carbon atom as a constituent unit.
The improver according to any one of claims 1 to 6, which is a polymer containing 70% by weight or more of an alkyl methacrylate monomer (B) having 0 or less alkyl group. 8. (B) is an alkyl methacrylate monomer (B-1) having an alkyl group having 1 to 4 carbon atoms and an alkyl methacrylate monomer (B-) having an alkyl group having 5 to 10 carbon atoms. The improving agent according to claim 7, which is used in combination with 2). 9. (B-1) is an alkyl methacrylate having an alkyl group having 1 and / or 4 carbon atoms,
The improver according to claim 8, wherein (B-2) is an alkyl methacrylate having an alkyl group having 8 carbon atoms. 10. The improver according to claim 1, wherein (PAA) is an alkyl acrylate polymer obtained by copolymerizing 35% by weight or less of an alkyl methacrylate monomer. 11. The improver according to claim 1, wherein (PMA) is an alkyl methacrylate polymer obtained by copolymerizing 35% by weight or less of an alkyl acrylate monomer. 12. The improver according to claim 1, further comprising a pour point depressant (C). 13. A total weight of (PAA) and (PMA) 1
The amount of (C) is 1 to 20 parts by weight with respect to 00 parts.
The improver described in 2. 14. The improver according to claim 1, which is for engine oil, gear oil, automatic transmission oil, power steering oil, or shock absorber oil. 15. A lubricating base oil selected from mineral oils, MLDW oils, high viscosity index mineral oils containing isomerized paraffin, hydrocarbon synthetic lubricating oils, ester synthetic lubricating oils and mixtures of two or more thereof. A lubricating oil obtained by adding the improver according to any one of claims 1 to 14 to (D). 16. The lubricating base oil (D) essentially contains a high viscosity index oil containing isomerized paraffin.
The lubricating oil according to 5. 17. An essential component comprises 0.3 to 30% by weight of the improver, 0.05 to 5% by weight of a molybdenum-based friction and wear inhibitor, and 99.45 to 65% by weight of a lubricating base oil (D). Item 15. The lubricating oil according to Item 15 or 16.