JP2003027077A - Viscosity index improver and lubricating oil composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a viscosity index improver that is excellent in shear stability and a lubricating oil composition comprising the viscosity index improver. SOLUTION: The viscosity index improver comprises a copolymer (A) comprising, as an essential constitutional unit, a unit derived from a radically copolymerizable monomer (a) represented by the formula (1): CH2 =C (OA)m-O- CH2 -CH=CH2 }2 wherein A is a 2-16C alkylene group; (m) denotes 0 or an integer of 1 or more, averaging 0-30; and the portion '(OA)m' may be the addition form of either random addition or block addition. The lubricating oil composition comprises the viscosity index improver.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a viscosity index improver and a lubricating oil composition. Specifically, it relates to a viscosity index improver having excellent shear stability and a lubricating oil composition containing the same.

[0002]

2. Description of the Related Art In recent years, there has been an increasing tendency to protect the global environment, and fuel saving and long life of automobiles have been further required. In order to improve the fuel efficiency of automobiles, a method of adding a viscosity index improver to a lubricating oil to make it into a multigrade is generally used. Further, in order to improve the long life of the lubricating oil, a method of improving shear stability is generally used. However, shear stability cannot be said to be sufficient with conventional PMA (polymethacrylate) viscosity index improvers, and improvement is needed.

[0003]

Conventionally, as a method for improving the shear stability of a PMA-based viscosity index improver, a method using PMA having a relatively low molecular weight has been proposed. However, although this method shows an improvement in shear stability,
There is a problem that the effect of improving the viscosity index and the effect of decreasing the low temperature viscosity are deteriorated.

[0004]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors to solve the above problems, a viscosity index improver comprising a specific copolymer (A) has excellent shear stability and a viscosity index. They have found that they are also excellent in improving effect and low temperature viscosity, and have reached the present invention. That is, the present invention provides a viscosity index improver comprising a copolymer (A) having a unit derived from a radical copolymerizable monomer (a) represented by the following general formula (1) as an essential constituent unit, and The lubricating oil composition contains. During _{CH 2 = C {(OA)} m-O-CH 2 -CH = CH 2} 2 (1) formula, A is an alkylene group having a carbon number of 2 to 20; m is an average 0-30 0 Alternatively, it represents an integer of 1 or more. (O
A) The m portion may be randomly added or block added.

DETAILED DESCRIPTION OF THE INVENTION

In the general formula (1), A has 2 to 2 carbon atoms.
An alkylene group of 0, specifically, ethylene group, propylene group, isobutylene group, 1-butylene group, 2-butylene group, 1-dodecene group, trimethylethylene group, tetramethylethylene group, styrene group, α-methyl Examples thereof include a styrene group. m is an integer of 0 or 1 with an average of 0 to 30, preferably an integer of 1 to 12.

Among A, ethylene group and propylene group are preferable, and (AO) m portion is particularly preferably represented by the following general formula (2). General formula [(C ₂ H ₄ O) p / (C ₃ H ₆ O) k] (2) In the formula, p is 0 to 12 (preferably 0 to 8) and k is 0 to 1
2 (preferably 0 to 8) and p + k is an integer of 0 to 12 (preferably 0 to 8). Of these, particularly preferred are p = 0 and k = 0, and p = 1 to 4 and K = 0.

[(C ₂ H ₄ O) p / (C ₃ H ₆ ) k] may be either random addition or block addition. Specific examples include ketene diallyl acetal _{[CH 2 = C {-O-} C
_{H 2 -CH = CH 2} 2} ], Ketenji (allyloxy) ethyl acetal _{[CH 2 = C {-O-} CH 2 CH 2 -O-
_{CH 2 -CH = CH 2} 2} ], Ketenji (allyloxyethyl) ethyl acetal _{[CH 2 = C {(OC} 2 H
_{4) 2 -O-CH 2 -CH} = CH 2} 2], Ketenji [allyloxy - poly (n = 6) (ethyloxy) ethyl acetal, Ketenji (allyloxy) propyl acetal, Ketenji [allyloxy - poly (N = 5) (propyloxy)] propyl acetal, ketene di (allyloxyethyloxy) propyl acetal, and the like. For synthetic methods of these compounds,
For example, Macromolecules, 24, 36
90 (1991) and the like, for example, in the production of ketene diallyl acetal, bromoacetaldehyde dimethyl acetal and allyl alcohol are reacted in the presence of an acid catalyst to remove the produced methanol, and then remove the excess allyl alcohol, Purify by vacuum distillation. The method of removing HBr of the obtained bromoacetaldehyde diallyl acetal under basic conditions is mentioned.

The preferred solubility parameter (S) of (a)
The range of P value is 8 to 10 (more preferably 8.1 to 1).
9.5). Within this range, it is preferable in terms of solubility and dispersibility in the polymerization solution.

In the present invention, the solubility parameter is determined by the method proposed by Fedors et al.
m. Eng. Sci. 14 (2) 147-154, (1
974)].

In the present invention, (A) is a copolymer of (a) and another monomer (b), and (b) is

(I) alkylalkenyl ether; alkyl vinyl ether having a linear or branched alkyl group having 1 to 30 carbon atoms, alkyl (meth) allyl ether,
Alkylpropenyl ether, alkyl isopropenyl ether and the like can be mentioned, and the alkyl group of these alkylalkenyl ethers includes; methyl group, ethyl group, n- and iso-propyl group,
n-, iso-, sec- and t-butyl groups, n-, iso-,
sec- and neopentyl group, hexyl group, heptyl group, n- and iso-octyl group, 2-ethylhexyl group, n- and iso-nonyl group, n- and iso-decyl group, n- and iso-dodecyl group, n -And iso-tridecyl groups, n- and iso-tetradecyl groups, n- and iso-pentadecyl groups, n- and iso-hexadecyl groups, n- and iso-octadecyl, eicosyl and docosyl and the like. Specifically, examples of the alkyl vinyl ether include methyl vinyl ether and ethyl vinyl ether, and examples of the alkyl (meth) allyl ether include alkyl propenyl ether and alkyl isopropenyl ether. Among these, preferably alkyl vinyl ether (more preferably methyl vinyl ether, ethyl vinyl ether and n
-Propyl vinyl ether), and alkyl (meth)
Allyl ether (more preferably methyl allyl ether and ethyl allyl ether).

(II) (Meth) acrylic acid alkyl ester: The alkyl group is a linear or branched alkyl group having 1 to 30 carbon atoms, and examples thereof include the same groups as in the above (I). Preferred is an alkyl group having 1 to 22 carbon atoms. As the (meth) acrylic acid alkyl ester,
(Meth) acrylic acid methyl ester, (meth) acrylic acid ethyl ester, (meth) acrylic acid propyl ester, (meth) acrylic acid isopropyl ester, (meth) acrylic acid butyl ester, (meth) acrylic acid isobutyl ester, (meth ) Acrylic acid sec-butyl ester, (meth) acrylic acid tert-butyl ester, (meth) acrylic acid pentyl ester, (meth) acrylic acid hexyl ester, (meth) acrylic acid 2-ethylhexyl ester, (meth) acrylic acid dodecyl ester , (Meth) acrylic acid tridecyl ester, (meth) acrylic acid tetradecyl ester, (meth) acrylic acid pentadecyl ester, (meth) acrylic acid hexadecyl ester, (meth) acrylic acid octadecyl ester, (meth) acrylic An acid eicosyl ester.

(III) Mono (meth) acrylic acid ester of (poly) alkylene glycol or its monoalkyl ether [(poly) alkylene glycol represents alkylene glycol and polyalkylene glycol. Hereinafter, similar expressions will be used. ] As an alkylene group which comprises (poly) alkylene glycol, a C2-C20 ethylene group, a propylene group, a butylene group, 2
-Butylene group, isobutylene group, α-C5-20
Alkylene group, trimethylethylene group, tetramethylethylene group, styrene group, α-methylstyrene group, 1,1
Examples include a diphenylethylene group, a cyclohexylene group, a trimethylene group, a tetramethylene group and a pentamethylene group. Preferably, it is an alkylene group having 2 to 6 carbon atoms. The number of alkylene glycol units in the (poly) alkylene glycol is usually 1 to 50, preferably 1 to
20, and the number average molecular weight is usually 60 to 2000, preferably 60 to 1000. Examples of the alkyl group constituting the monoalkyl ether include those having 1 to 20 carbon atoms, preferably those having 1 to 18 carbon atoms, among the alkyl groups of the above (I). Specific examples of the mono (meth) acrylic acid ester of (poly) alkylene glycol or its monoalkyl ether include polyethylene glycol (the number of ethylene glycol units is 9), mono (meth) acrylate, and polyethylene glycol (the number of ethylene glycol units is 18).
Mono (meth) acrylate, polypropylene glycol (propylene glycol unit number 3) mono (meth) acrylate, polyethylene glycol (ethylene glycol unit number 6) monomethyl ether mono (meth) acrylate, ethylene glycol mono-2-ethylhexyl ether mono ( Examples thereof include (meth) acrylate and polypropylene glycol (the number of units of propylene glycol is 3) monobutyl ether mono (meth) acrylate.

The poly (glycidyl ether) of the mono (meth) acrylic acid ester (IV) of (IV) poly (glycidyl ether) has an alkyl group, an alkenyl group or an aromatic ring having 1 to 12 carbon atoms. Alkyl glycidyl ether,
Examples of the polymer obtained by ring-opening polymerization of a glycidyl group of an alkenyl glycidyl ether or an aromatic glycidyl ether, and the alkyl glycidyl ether,
For example, ethyl glycidyl ether, n-propyl glycidyl ether, n- and iso-butyl glycidyl ether, n-hexyl glycidyl ether, 2-ethylhexyl glycidyl ether, and the like. As alkenyl glycidyl ether, allyl glycidyl ether, methallyl glycidyl ether, propenyl. Examples of aromatic glycidyl ethers such as glycidyl ether include phenyl glycidyl ether. The number of glycidyl ether units of poly (glycidyl ether) is usually 1
-30, preferably 1-20, and the number average molecular weight is usually 60-2000, preferably 60-1000.

(V) Fatty acid vinyl ester: A vinyl ester of a fatty acid in which an alkyl group constituting a fatty acid has 1 to 30 carbon atoms (straight or branched alkyl group), and the alkyl group is the above-mentioned (I). The same groups as those described above, preferably an alkyl group having 1 to 22 carbon atoms, and more preferably 1 to 10 carbon atoms. Specifically, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl hexanoate, vinyl heptanoate, vinyl 2-ethylhexanoate and n.
-Vinyl octanoate and the like.

(VI) Nitrogen atom-containing monomer; (VI-1) Amido group-containing vinyl monomer: For example, unsubstituted or monoalkyl (C1-4) substituted (meth)
Acrylamide, [(meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-i-propyl (meth) acrylamide,
N-n- and i-butyl (meth) acrylamide, etc.], dialkyl (C1-4) substituted (meth) acrylamide [N, N-dimethyl (meth) acrylamide,
N, N-diethyl (meth) acrylamide, N, N-di-n-butyl (meth) acrylamide], N-vinylcarboxylic acid amide [N-vinylformamide, N-vinylacetamide, N-vinyl-n- and i- Propionylamide, N-vinylhydroxyacetamide] or the like having a nitrogen atom only in the amide group, (VI-2) nitro group-containing monomer: for example, 4-nitrostyrene, etc., (VI-3) primary to tertiary Amino group-containing vinyl monomer: Primary amino group-containing vinyl monomer, for example, alkenylamine having 3 to 6 carbon atoms [(meth) allylamine, crotylamine, etc.], aminoalkyl (having 2 to 6 carbon atoms) (meth) Acrylate [aminoethyl (meth) acrylate, etc.] Secondary amino group-containing vinyl monomer, for example, alkyl (C 1-6) Noarukiru (2 to 6 carbon atoms)
(Meth) acrylate [t-butylaminoethyl methacrylate, methylaminoethyl (meth) acrylate, etc.], diphenylamine (meth) acrylamide [4-
Diphenylamine (meth) acrylamide, 2-diphenylamine (meth) acrylamide, etc.], carbon number 6 to
12 dialkenylamine [di (meth) allylamine etc.] tertiary amino group-containing vinyl monomer, for example, dialkyl (C1-4) aminoalkyl (C2-6)
(Meth) acrylate [dimethylaminoethyl (meth)
Dialkyl (C1-4) aminoalkyl (C2-6) (meth) acrylamides such as acrylate and diethylaminoethyl (meth) acrylate [dimethylaminoethyl (meth) acrylamide, diethylaminoethyl (meth) acrylamide, dimethylaminopropyl (Meth) acrylamide etc.] Tertiary amino group-containing aromatic vinyl monomer [N, N-dimethylaminostyrene,
Etc.], nitrogen-containing heterocycle-containing vinyl monomers [morpholinoethyl (meth) acrylate, 4-vinylpyridine, 2
-Vinylpyridine, N-vinylpyrrole, N-vinylpyrrolidone, N-vinylthiopyrrolidone, etc.], and their hydrochlorides, sulfates, phosphates, lower alkyl (C 1-8) monocarboxylic acid salts (for example, (VI-4) quaternary ammonium salt group-containing vinyl monomer: for example, the above-mentioned tertiary amino group-containing vinyl monomer,
Examples thereof include those quaternized with a quaternizing agent (alkyl chloride having 1 to 12 carbon atoms, dialkyl sulfuric acid, dialkyl carbonate, benzyl chloride and the like). Specifically, examples of the alkyl (meth) acrylate-based quaternary ammonium salt include (meth) acryloyloxyethyltrimethylammonium chloride, (meth) acryloyloxyethyltriethylammonium chloride, and (meth) acryloyloxyethyldimethylbenzylammonium. Chloride, (meta)
Acryloyloxyethylmethylmorpholino ammonium chloride, etc .; Examples of alkyl (meth) acrylamide-based quaternary ammonium salts include (meth) acryloylaminoethyltrimethylammonium chloride, (meth) acryloylaminoethyltriethylammonium chloride, (meth) acryloylamino Ethyl dimethyl benzyl ammonium chloride, etc .; Other quaternary ammonium salt group-containing vinyl monomers include, for example, dimethyl diallyl ammonium methyl sulfate, trimethyl vinyl phenyl ammonium chloride, etc. (VI-5) Amphoteric vinyl monomer: N -(Meth) acryloyloxy (or amino) alkyl (C1 to C1
0) N, N-dialkyl (C1-5) ammonium-N-alkyl (C1-5) carboxylate (or sulfate), for example, N- (meth) acryloyloxyethyl N, N-dimethylammonium N -Methylcarboxylate, N- (meth) acryloylaminopropyl N, N-dimethylammonium N-methylcarboxylate, and N- (meth) acryloyloxyethyl N, N-dimethylammonium propylsulfate, (VI-6) nitrile Group-containing monomer: (meth) acrylonitrile, etc.,

(VII) Aliphatic hydrocarbon vinyl monomer: for example, an alkene having 2 to 20 carbon atoms [ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, etc.], and Alkadienes having 4 to 12 carbon atoms [butadiene, isoprene, 1,4-pentadiene, 1,6 heptadiene, 1,7-octadiene, etc.],

(VIII) Alicyclic hydrocarbon vinyl monomer: For example, cyclohexene, (di) cyclopentadiene, pinene, limonene, indene, vinylcyclohexene, ethylidene bicycloheptene, etc.

(IX) Aromatic hydrocarbon vinyl monomer:
For example, styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, 4-ethylstyrene,
4-isopropylstyrene, 4-butylstyrene, 4-
Phenyl styrene, 4-cyclohexyl styrene, 4-
Benzylstyrene, 4-crotylbenzene, and 2-
Vinyl naphthalene, etc.

(X) Vinyl ketones: For example, carbon number 1
~ 8 alkyl or aryl vinyl ketone [methyl vinyl ketone, ethyl vinyl ketone, phenyl vinyl ketone, etc.],

(XI) Epoxy group-containing vinyl monomer; for example, glycidyl (meth) acrylate, glycidyl (meth) allyl ether,

(XII) halogen-containing vinyl monomer; for example, vinyl chloride, vinyl bromide, vinylidene chloride, (meth) allyl chloride, halogenated styrene (dichlorostyrene, etc.), etc.

(XIII) Diester of unsaturated dicarboxylic acid; for example, alkyl of unsaturated dicarboxylic acid [maleic acid, fumaric acid, itaconic acid, etc.] (having 1 to 1 carbon atoms)
2), cycloalkyl (having 4 to 24 carbon atoms) and aralkyl (having 7 to 18 carbon atoms) diesters, of which alkyl diesters having 1 to 8 carbon atoms [dimethyl maleate, dimethyl fumarate, diethyl maleate. , Dioctyl maleate, etc.] are preferred.

(XIV) Hydroxyl group-containing vinyl monomer; for example, hydroxyl group-containing aromatic vinyl monomer [p-hydroxystyrene, etc.], hydroxyalkyl (C2-6) (meth) acrylate [2-hydroxy Ethyl (meth) acrylate, 2 or 3-hydroxypropyl (meth) acrylate, etc.], mono- or di-hydroxyalkyl (having 1 to 4 carbon atoms) substituted (meth)
Acrylamide [N, N-dihydroxymethyl (meth)
Acrylamide, N, N-dihydroxypropyl (meth) acrylamide, N, N-di-2-hydroxybutyl (meth) acrylamide, etc.], vinyl alcohol (formed by hydrolysis of vinyl acetate unit), carbon number 3 to 12 Alkenol [(meth) allyl alcohol, crotyl alcohol, isocrotyl alcohol, 1
-Octenol, 1-undecenol, etc.], carbon number 4
~ 12 alkendiol [1-buten-3-ol,
2-buten-1-ol, 2-butene-1,4-diol, etc.], hydroxyalkyl (C 1-6) alkenyl (C 3-10) ether [2-hydroxyethylpropenyl ether, etc.], polyvalent (3 to 8 valent) alcohol (alkane polyol, its intramolecular or intermolecular dehydration product, saccharide, for example, glycerin, pentaerythritol, sorbitol, sorbitan, diglycerin, sucrose)
Alkenyl (C3-10) ether or (meth) acrylate [sucrose (meth) allyl ether],

(XV) Ionic group-containing vinyl monomer; (XV-1) Anionic group-containing vinyl monomer: unsaturated monocarboxylic acid [(meth) acrylic acid, α-methyl (meth) acrylic acid, Crotonic acid, cinnamic acid, etc.], unsaturated dicarboxylic acids [maleic acid, fumaric acid, itaconic acid, citraconic acid, etc.], and unsaturated dicarboxylic acid monoalkyl (C 1-8) esters [maleic acid monomethyl ester, fumaric acid] Acid monoethyl ester, itaconic acid monobutyl ester, etc.].

(XV-2) Sulfonic acid group-containing vinyl monomer: For example, alkene sulfonic acid having 2 to 6 carbon atoms [vinyl sulfonic acid, (meth) allyl sulfonic acid, etc.], aromatic having 6 to 12 carbon atoms Vinyl group-containing sulfonic acid [α-methylstyrene sulfonic acid, etc.], Sulfonic acid group-containing (meth) acrylic ester monomer [sulfopropyl (meth) acrylate, 2- (meth) acryloyloxyethane sulfonic acid, etc.], sulfone Acid group-containing (meth) acrylamide-based monomer [2- (meth) acrylamide-2
-Methylpropanesulfonic acid, etc.], vinyl monomers containing sulfonic acid groups and hydroxyl groups [3- (meth) acrylamido-2-hydroxypropanesulfonic acid, 3-allyloxy-2-hydroxypropanesulfonic acid, 3- (meth ) Acryloyloxy-2-hydroxypropane sulfonic acid, etc.], alkyl (C3-18) allyl sulfosuccinate [dodecyl allyl sulfosuccinate], etc.

(XV-3) Sulfate group-containing vinyl monomer: For example, poly (n = 2-30) oxyalkylene (ethylene, propylene, butylene: alone, random,
Sulfuric acid ester of mono (meth) acrylate of block (may be block), poly (n = 2 to 30) oxyalkylene (ethylene, propylene, butylene: alone, random, may be block) Sulfuric acid ester of bisphenol A mono (meth) acrylate, etc.,

(XV-4) Phosphoric acid group-containing vinyl monomer: For example, (meth) acryloyloxyalkyl (having 2 carbon atoms)
To 6) phosphoric acid monoester [(meth) acryloyloxyethyl phosphate, etc.], (meth) acryloyloxyphosphonic acid [2-acryloyloxyethylphosphonic acid], etc.,

As (XV), these salts may be used. Examples of salts include alkali metal salts [lithium salts, sodium salts and potassium salts], amine salts [eg, primary amines having 1 to 10 carbon atoms (methylamine, ethylamine, propylamine, monoethanolamine, phenylamine, etc.).
Salt with: a salt with a secondary amine having 1 to 20 carbon atoms (such as dimethylamine, diethylamine, diethanolamine and diphenylamine): and 3 having 1 to 30 carbon atoms
Salts with secondary amines (such as trimethylamine, triethylamine, triethanolamine and triphenylamine)], ammonium salts and quaternary ammonium salts [eg, quaternary ammonium salts having an alkyl, alkenyl or aralkyl group having 1 to 12 carbon atoms] (Tetramethylammonium salt, tetraethylammonium salt, tetramethylethylammonium salt, trimethylbenzylammonium salt, triethylbenzylammonium salt, trimethyldodecylammonium salt, etc.)].

Of the monomers (b) other than (a), (I) alkylalkenyl ether and (II) are preferable.
(Meth) acrylic acid alkyl ester and (V) fatty acid vinyl ester.

The content of the unit derived from the monomer (a) in the copolymer (A) of the present invention is usually 0.001 to 1% by mass, preferably 0, based on the mass of (A). ．
005 to 0.3% by mass, and the content of (b) is 99 to
99.999% by mass, preferably 99.7-99.99.
It is 5% by mass. If the content of the units derived from the monomer (a) is 0.001% or more, the effect of using (a), that is, the effect of improving the viscosity index, should be the same level and only the shear stability should be improved. You can On the other hand, when the content is 1% or less, the polymerization rate and the polymerization rate of the polymerization system containing the monomer (a) during the production of the copolymer (A) do not decrease, and the productivity is good.

It is also possible to carry out the polymerization by dissolving or dispersing the monomer (a) in a polymerization solution in combination with a surfactant and the like.

Among the monomers (b) used in (A),
The proportion of the alkyl alkenyl ether used is preferably 2 to 100% by weight in (b), the proportion of the (meth) acrylic acid alkyl ester is preferably 10 to 100% by weight in (b), and the fatty acid vinyl ester is preferably used. The use ratio of (b) is preferably 0 to 45% by mass, and the use ratio of (meth) acrylonitrile is preferably 0 to 12% by mass of (b). Particularly preferably, the total amount of the alkyl alkenyl ether and the (meth) acrylic acid alkyl ester is 30 to 100% by weight based on the total amount of all the constituent monomers.

The weight average molecular weight of the copolymer (A) of the present invention is usually 5,000 to 500,000, preferably 8,
000 to 300,000, more preferably 10,000
It is 0 to 250,000. When it is 5,000 or more, the thickening effect is good, and when it is 500,000 or less, the shear stability is further good. The weight average molecular weight is a weight average molecular weight calculated by converting to polystyrene by gel permeation chromatography.

The solubility parameter of the copolymer (A) of the present invention is usually 8.6 to 9.4, preferably 8.8 to.
It is 9.3, more preferably 8.8 to 9.2, and the solubility parameter in the range of 8.6 to 9.4 has good solubility in the base oil.

The crystallization start temperature of the polymer (A) measured by a differential scanning calorimeter is usually -15 ° C or lower, preferably -20 ° C or lower, more preferably -25 ° C or lower. When the temperature is lower than -15 ° C, the low temperature characteristics are good. The crystallization start temperature measured by the differential scanning calorimeter of the present invention is PERK.
Using "DSC7" manufactured by IN-ELMER, using 5 mg of a viscosity index improver as a sample, an isothermal rate of 10 ° C / min was used for 14
It is a crystallization start temperature observed when cooled from 0 ° C to -40 ° C.

Further, in the polymer (A) used in the present invention, the average value of the steric hindrance factor (F) represented by the following general formula (2) is usually 0 to 20, preferably 0 to 15, and further. It is preferably 0 to 13. F = 4X + Y (1) When the average value of the steric hindrance factor (F) is 20 or less, the steric hindrance around the main chain is further reduced, shrinkage easily occurs at low temperature, and the low temperature viscosity and the viscosity index are further improved.

The steric hindrance factor (F) is the 6th position counted in the direction of the side chain when the atom of the main chain to which the side chain is bonded is 0th in the constituent monomer unit of (A). 4 of the total number of atoms (X) (regardless of the type of atom)
Times the total number of atoms located at the 7th position (Y) (regardless of the type of atom), and when (A) is a copolymer, it constitutes (F) of each structural unit. It is a value averaged based on the mole fraction of the monomer unit. The steric hindrance factor (F) conveniently represents the degree of steric hindrance of the side chain viewed from the polymer main chain, and the larger the number, the greater the steric hindrance. The calculation example is as follows. The numbers on the right side of the atoms indicate the order of the atoms from the main chain. When there are a plurality of side chains, the total calculated for them is also (F).

[0039] Example a) In the case of n-hexyl methacrylate unit

[0040]

[Chemical 1]

6th atom number = 3, 7th atom number = 3 Steric hindrance factor (F) = 3 × 4 + 3 = 15

The HLB value of (A) is preferably 0.5 to 6.0. When this physical property value is within this range, the anti-emulsification property is particularly good. Preferably, the HLB value is 1.0 to 5.5. More preferably, the HLB value is 1.5 to 5.0. The HLB value of the present invention is the H of the organic / inorganic concept.
It is a value calculated by LB ("New surfactant introduction" Sanyo Kasei Kogyo Co., Ltd., P197-198).

The production method of (A) in the present invention may be a conventionally known radical polymerization method, for example, a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, a reverse phase suspension polymerization method, a thin film polymerization method. Examples thereof include a legal method and a spray polymerization method, and a solution polymerization method is preferable. Examples of the polymerization control method include adiabatic polymerization method and temperature control polymerization method. In addition to the method of initiating the polymerization with an initiator such as an azo compound initiator, a peroxide compound initiator, a redox initiator, a method of initiating the polymerization by irradiating with radiation, an electron beam, or an ultraviolet ray may be adopted. it can.
Preferred is a solution polymerization method using an azo compound initiator, a peroxide compound initiator, and a redox initiator.

The polymerization solvent that can be used for solution polymerization is
Eg containing solvent refined oils, isoparaffins and / or
Or high viscosity index oil by hydrocracking, hydrocarbon synthetic lubricating oil, ester synthetic lubricating oil, naphthene oil, highly volatile hydrocarbon solvent [(pentane, hexane, etc.), aromatic solvent (toluene, xylene) Etc.]], alcohol solvents (octal, butanol, etc.), ketone solvents (methyl isobutyl ketone, methyl ethyl ketone, etc.), amide solvents (N, N-dimethylformamide, N-methylpyrrolidone, etc.), and sulfoxide solvents (dimethyl). Sulfoxide and the like).

The polymerization reaction temperature is 50 to 140 ° C.,
It is preferably 70 to 120 ° C. Further, the monomer may be polymerized in either random copolymerization or alternating copolymerization, or may be graft copolymerization or block copolymerization.

As the polymerization initiator, conventionally known initiators can be used, and examples thereof include an azo type initiator, a peroxide type initiator and a redox type initiator. As the azo-based initiator, azobisisobutyronitrile, azobiscyanovaleric acid and salts thereof, 2,2'-azobis (2-amidinopropane) hydrochloride, 2,2'-azobis (2
-Methyl-N- (2-hydroxyethyl) propionamide and the like. As the peroxide type initiator, inorganic peroxides [hydrogen peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, etc.], organic peroxides [benzoyl peroxide, di-t-butyl peroxide, cumene hydroper] Oxide, succinic acid peroxide, di (2-
Ethoxyethyl) peroxydicarbonate and the like], and further, as the redox initiator, sulfite or bisulfite of an alkali metal, ammonium sulfite, ammonium bisulfite, ferric chloride, ferric sulfate,
Examples thereof include a combination of a reducing agent such as ascorbic acid and an oxidizing agent such as an alkali metal persulfate, ammonium persulfate, hydrogen peroxide, and an organic peroxide. These initiators may be used alone or in combination of two or more. The amount of the polymerization initiator used is preferably 0.0005 to 5% by mass, based on the mass of (A),
More preferably, it is 0.001 to 2 mass%.

A chain transfer agent may be used, and examples thereof include thiols (n-lauryl mercaptan, mercaptoethanol, mercaptopropanol, triethylene glycol dimercaptan, etc.), thiol carboxylic acids (thiol). Glycolic acid, thiomalic acid, etc., secondary alcohols (isopropanol, etc.), amines (dibutylamine, etc.), hypophosphite salts (sodium hypophosphite, etc.), etc., and the amount of chain transfer agent Is preferably 0.001 to 1 mass% with respect to the amount of all vinyl-based monomers.

In the lubricating oil composition of the present invention comprising the viscosity index improver and the base oil, the cloud point of the base oil used (JIS K2
269) is preferably -10 ° C or lower. It is preferably -15 ° C or lower. When the cloud point of the base oil is within this range, the amount of wax deposited is small and the low temperature viscosity is good. Also, 100 of base oil
It is preferable that the kinematic viscosity at ² ° C. is ² to 6 mm ² / s. ,
Examples of the base oil include solvent refined oils, high-viscosity index oils containing isoparaffin and / or hydrocracked, hydrocarbon synthetic lubricating oils, ester synthetic lubricating oils, naphthene oils, and mixtures of two or more thereof. To be

The viscosity index improver of the present invention is preferably added to the base oil in an amount of 1 to 30% by mass and used as the lubricating oil composition of the present invention. The lubricating oil composition of the present invention is 2 to 10% by weight when it is an engine oil, 7 to 25% by weight when it is a gear oil or an automatic transmission oil, and 0.5 when it is a traction oil.
It gives favorable results when it is added in an amount of 10% by weight.

The lubricating oil composition of the present invention comprises other optional components,
For example, detergents (sulfonate, salicylate, phenate, naphthenate, etc.), dispersants (isobutenyl succinimide, Mannich condensation products, etc.),
Antioxidants (zinc dithiophosphate, amine, hindered phenol, etc.), oiliness improvers (fatty acid, fatty acid ester, etc.), friction and wear modifiers (molybdenum dithiophosphate, molybdenum carbamate, etc.), extreme pressure agents ( Sulfur-phosphorus-based, chloro-based, etc.) may be contained.

[0051]

The present invention will be further described below with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, all parts below refer to parts by mass. The following abbreviations were used in the examples. KAA; ketene diallyl _{acetal: CH 2 = C {O-} CH 2 -CH = CH 2} 2 SP value = 8.3 KAEOA; Ketenji (allyl oxyethyl) ethyl _{acetal: CH 2 = C {(OC} 2 H 4 ) ₂ -O-CH ₂ -CH = CH
₂ } ₂ SP value = 8.7 [Measurement method of weight average molecular weight by GPC] Device: HLC-802A column manufactured by Toyo Soda Co., Ltd .: TSK gel GMH6 2 measurement temperature: 40 ° C Sample solution: 0.5 wt% THF solution Injection volume of solution: 200 μl Detection device: Refractive index detector standard: Polystyrene

(Test Method for Shear Stability) JASO M3
It measured by the method of 47-95.

(Testing method for viscosity index) JIS-K-22
83 method.

Example 1 1,500 parts of toluene, 7,650 parts of dodecyl methacrylate as a monomer, and 850 parts of methyl methacrylate were placed in a reaction vessel equipped with a stirrer, a heating device, a cooling device, a thermometer, and a nitrogen blowing tube. , 10 parts of KAA, 40 parts of azobisvaleronitrile as a polymerization initiator, and 42 parts of dodecyl mercaptan as a chain transfer agent were charged, and after nitrogen substitution, a polymerization reaction was carried out at 85 ° C. for 4 hours under a closed atmosphere. The obtained polymer was reprecipitated with 10,000 parts of methanol, washed twice with 8,700 parts of methanol, and then dried under reduced pressure at 100 ° C. for 4 hours to produce a copolymer (A1), which had a viscosity of the present invention. It was used as an index improver (Ex. 1).

Example 2 A copolymer (A2) was obtained in the same manner as in Example 1 except that 1,275 parts of methyl methacrylate, 6,375 parts of dodecyl methacrylate and 850 parts of tetradecyl methacrylate were used as monomers. This was designated as the viscosity index improver (Ex. 2) of the present invention.

Example 3 A copolymer (A3) was obtained in the same manner as in Example 1 except that KAA was changed to KAEOA. This was designated as the viscosity index improver (Exemplary 3) of the present invention.

Example 4 A copolymer (A4) was obtained in the same manner as in Example 2 except that KAE was changed to KAE0A. This was designated as the viscosity index improver (Execution 4) of the present invention.

Comparative Example 1 A comparative copolymer (X1) was obtained in the same manner as in Example 1 except that KAA was not used. This was designated as the viscosity index improver of the present invention (ratio 1).

Comparative Example 2 A comparative copolymer (X2) was obtained in the same manner as in Example 2 except that KAA was not used. This was obtained as a viscosity index improver (ratio 2) of the present invention.

The obtained viscosity index improvers (Ex. 1) to (Ex. 4), (Ratio 1) and (Ratio 2) were used as high viscosity index oils (cloud point: -1).
Dissolve in kinematic viscosity at 5 ° C and 100 ° C: 4.0 mm ² / s) to prepare a lubricating oil. Then, the concentration of the viscosity index improver was adjusted so that the kinematic viscosity of the lubricating oil at 100 ° C. was 6.6 (mm ² / s) to prepare a test oil, and the shear stability and the viscosity index were evaluated.

[0061]

[Table 1]

[0062]

INDUSTRIAL APPLICABILITY The copolymer obtained by the present invention has good shear stability, and when it is used as a viscosity index improver and a lubricating oil composition containing the same, it has a remarkable effect as compared with the conventional one. . That is, the lubricating oil composition using the viscosity index improver comprising the polymer of the present invention can improve the shear stability as compared with the lubricating oil composition using the conventional PMA viscosity index improver, and the viscosity Since the index is high and the low temperature viscosity is low, we can meet future demands for fuel economy and long life of automobiles, so drive system lubricating oil, hydraulic oil, engine oil,
It can be suitably used for traction oil and the like. Also,
The resulting copolymer can be used in various applications depending on the type and amount of the monomer used, the molecular weight and the like. It can be obtained in liquid form at room temperature, from viscous to solid. When the polymer obtained as an example is, for example, (i) a water-dispersible polymer; a polymer for aqueous paints, an aqueous coating agent, a photoresist, a sizing agent, a conductive agent, an antistatic agent for fibers, an antifouling agent for fibers, Resin processing binder, non-woven fabric binder, plastic reinforcing fiber binder, magnetic tape binder, resin concrete binder, dye paste, adhesive, civil engineering thickener, primer, pigment dispersant, agricultural chemical granule dispersant, Dispersant for pulverized coal, dispersant for cement, scale inhibitor, compatibilizer, drainage / retention improver, binder for printing ink, flocculant, dye fixing agent, chelate polymer, polymer for hair setting, etc. (ii) Oil When it is a soluble polymer; water-absorbent resin, oil-absorbent resin, polymer for increasing crude oil production, gelling agent, plasticizer, plastic kneading antistatic agent, sealant It is useful as a stiffening agent, an elastomer, an electrophotographic toner binder, a printing ink binder, a magnetic tape binder, a lubricating oil detergent dispersant, a viscosity index improver, a filler, and the like, and is particularly useful as a viscosity index improver.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08F 290/06 C08F 290/06 C10M 145/08 C10M 145/08 145/14 145/14 // C10N 20: 00 C10N 20:00 AZ 20:02 20:02 20:04 20:04 30:02 30:02 30:06 30:06 F-term (reference) 4H104 CB02C CB04C CB08C EA01C EA02A EA03C EA04A EA04C LA01 LA03 4J027 AC01 AC02 AC07 BA02 BA04 BA07 CB09 CC02 CD00 4J100 AE02Q AE03Q AE04Q AE13Q AE83P AF01P AG01Q AG04Q AL02Q AL03Q AL04Q AL05Q AL08Q BA02P BA08P BA08Q CA04 CA23 DA01 DA22 DA39 JA28

Claims (7)

[Claims] 1. A viscosity index improver comprising a copolymer (A) having a unit derived from a radical copolymerizable monomer (a) represented by the following general formula (1) as an essential constituent unit. _{CH 2 = C {(OA)} m-O-CH 2 -CH = CH 2} 2 (1) [ in the formula, A is an alkylene group having 2 to 16 carbon atoms; m is an average 0-30 Indicates an integer of 0 or 1 or more.
The (OA) m portion may be randomly added or block added. ] 2. The solubility parameter (SP value) of (a)
Is 8 to 11, and the viscosity index improver according to claim 1. 3. The content of units derived from (a) is
The viscosity index improver according to claim 1 or 2, which is 0.001 to 1 mass% based on the mass of (A). 4. (A) is an alkylalkenyl ether,
The viscosity index improver according to any one of claims 1 to 3, which is a copolymer of (a) with one or more vinyl monomers selected from the group consisting of (meth) acrylic acid alkyl esters and fatty acid vinyl esters. 5. The viscosity index improver according to claim 1, wherein (A) satisfies all of the following (1) to (4). (1) Weight average molecular weight is 5,000 to 500,000 (2) Solubility parameter is 8.6 to 9.4 (3) Crystallization initiation temperature by differential scanning calorimeter is -15 ° C.
The value obtained by averaging the steric hindrance factors (F) represented by the following general formula (2) (4) based on the mole fraction of the constituent units is 0.
-20 General formula F = 4X + Y (2) {In each structural unit, let X be the total number of atoms located at the 6th position from the main chain in the side chain, and Y be the total number of atoms located at the 7th position. } 6. The viscosity index improver according to claim 1, wherein the HLB value of (A) is 0.5 to 6.0. 7. A kinematic viscosity at 100 ° C. of ² to 6 mm ²
/ S, a pour point is -10 degreeC or less, and the lubricating oil composition containing the viscosity index improver in any one of Claims 1-6.