JP2001348587A - Viscosity index improver and lubricating oil composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a viscosity index improver for further lowering a low- temperature viscosity. SOLUTION: This viscosity index improver comprises an oil-soluble polyalkylene (thio)ether satisfying (i) 11,000-250,000 number-average molecular weight, (ii) 8.6-9.4 solubility parameter, (iii) <=-15 deg.C crystallization starting temperature by a differential scanning calorimeter, (iv) <=12 steric hindrance factor (F) and general formula (1): R-Z-[(Y-Z)q(X-Z)p-(Y-Z)q]s-R X is an alkylene group having >=8.650 solubility parameter of (X-Z)p part; Y is an alkylene group having <8.650 solubility parameter of (Y-Z)q part and (X-Z)p and (Y-Z)q are each constituted of a random copolymer; Z is O or S; p and q are each an integer of >=2 and s is an integer of >=1; number-average molecular weight of A is 11,000 to 250,000; R is H or a 1-18C hydrocarbyl or acyl group} or its derivative (A).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a viscosity index improver and a lubricating oil composition containing the same. More specifically, the present invention relates to a viscosity index improver excellent in low-temperature properties 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 there has been a further demand for more fuel-efficient automobiles. In order to improve the fuel efficiency of automobiles, there is a method of adding a viscosity index improver to engine oil to make it multi-grade. In Japan, nearly 30% of engine oils used in diesel engine vehicles are multi-grade oils to which a viscosity index improver is added. In general, a multi-grade engine oil using a viscosity index improver (hereinafter abbreviated as a PMA viscosity index improver) composed of a polymer containing an ester group typified by a (meth) acrylate polymer, Good with little change in viscosity due to temperature change.

[0003]

However, recently, further improvement in fuel efficiency is required, and further lowering of the viscosity of the engine oil at a low temperature is required, so that the viscosity at a low temperature is higher than that of a conventional PMA-based viscosity index improver. There is a need for lower viscosity index improvers.

[0004]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a polymer composed of a specific monomer and a derivative of a specific compound and having specific physical properties has excellent low-temperature properties. This led to the present invention.

That is, the present invention relates to a viscosity index improver comprising an oil-soluble polyalkylene (thio) ether or a derivative thereof (A) satisfying the following (i) to (iv) and the formula (1): Lubricating oil composition. (I) the number average molecular weight is 11,000 to 250,000 (ii) the solubility parameter is 8.6 to 9.4 (iii) the crystallization onset temperature by differential scanning calorimetry is -15
° C or less (iv) Sterile hindrance factor (F) is 12 or less R-Z-[(YZ) q- (XZ) p- (YZ) q] s-R (1) X is an alkylene group having a solubility parameter of (XZ) p of 8.650 or more; Y is (YZ) q
P is an alkylene group having a solubility parameter of less than 8.650, and (XZ) p and (YZ) q are each composed of a random copolymer; Z is an O or S atom; p And q are integers of 2 or more, s is an integer of 1 or more, and the number average molecular weight of (A) is 11,00.
R is H, a hydrocarbyl group having 1 to 18 carbon atoms, and a carbon atom having 1 to 18 carbon atoms.
Represents one or more groups selected from the group consisting of acyl groups of

[0006]

DETAILED DESCRIPTION OF THE INVENTION The polyalkylene (thio) of the present invention
Ether or its derivative (A) is oil-soluble. Here, the oil solubility means that when 100 parts by weight of spindle oil {SY Pure Spin C: Cosmollicants Co., Ltd.} and 20 parts by weight of a viscosity index improver are added and mixed, they are compatible at any temperature of 0 to 85 ° C. Say that. Further, (A) needs to satisfy the above equation (1). In the equation (1), s is 1
It is the above integer, preferably an integer of 1 to 3. R
Examples of the C1-18 hydrocarbyl group include an alkyl group having 1 to 18 carbon atoms, an alkenyl group, an aralkyl group, an aryl group, and an alkylaryl group. As the acyl group having 1 to 18 carbon atoms, An aliphatic or aromatic carboxylic acid acyl group having 1 to 18 carbon atoms is exemplified.

In the polyalkylene (thio) ether or derivative (A) of the present invention, X is (XZ) p
Y is an alkylene group in which the solubility parameter of the moiety is 8.650 or more, and Y is an alkylene group in which the solubility parameter of the (YZ) q moiety is less than 8.650.
Here, (XZ) p and (YZ) q are composed of a random copolymer, and the solubility parameter is a value averaged based on the mole fraction of the monomer constituting the copolymer. is there. The solubility parameter in the present invention is Fe
dors method [Polym. Eng. Sci. 14 (2)
152, (1974)].

The following are examples of the monomer constituting (A) of the present invention. Cyclic ethers ethylene oxide (hereinafter abbreviated as EO), 1,2-propylene oxide (PO), 1,3-propylene oxide, isobutylene oxide, 1,2-butylene oxide (BO), 2,3-butylene oxide, , 3
-Butylene oxide, trimethylethylene oxide, tetramethylethylene oxide, cyclohexene oxide, oxetane, tetrahydrofuran, tetrahydropyran, 1,2-pentene oxide, 1,2-
Hexene oxide], an α-olefin oxide having 7 to 20 carbon atoms [1,2-octene oxide (O
O), 1,2-dodecene oxide, etc.], aromatic hydrocarbon group-substituted alkylene oxides [styrene oxide (SO), α-methylstyrene oxide, 1,1-diphenylethylene oxide, etc.], unsaturated aliphatic hydrocarbons Group-substituted alkylene oxides (butadiene monooxide, vinylcyclohexene monooxide, etc.), epihalohydrins (epifluorohydrin, epichlorohydrin, epibromohydrin, etc.). Glycidyl ethers (such as those having an alkyl group, alkenyl group, or aryl group having 1 to 10 carbon atoms; for example, butyl glycidyl ether, n-hexyl glycidyl ether, allyl glycidyl ether, phenyl glycidyl ether, etc .; For example, 2-
Chloroethyl glycidyl ether), having 3 to 5 carbon atoms
Glycidyl esters (eg, glycidyl methacrylate, glycidyl acrylate, etc.) of saturated or unsaturated monocarboxylic acids (eg, methacrylic acid, acrylic acid, crotonic acid), and cyclic thioethers, such as glycidol; Of a structure in which a ring-forming oxygen atom is replaced by a sulfur atom,
For example, ethylene sulfide, isobutylene sulfide, styrene sulfide, etc.

Of these, the monomer constituting the (XZ) p moiety is preferably EO, PO, 1,3-propylene oxide, tetrahydrofuran, SO;
Z) The monomer constituting the q portion is preferably 1,2
-Butylene oxide (BO), 1,2-pentene oxide, 1,2-hexene oxide, having 7 to 20 carbon atoms
Is an α-olefin oxide. It is easy to be.

From the viewpoint of the solubility and viscosity characteristics of (A), the average number of carbon atoms based on the mole fraction of the monomer constituting the polyalkylene (thio) ether moiety of (A) is 2.2 to 2.2. A combination of monomers that gives 6.2 is preferred. A more preferred range is from 3.0 to 4.5.
Of these, [(YZ) q- (X
-Z) p- (YZ) q] s is composed of 50% by weight or more of BO, particularly preferably 75% by weight or more of BO.

As a method of ring-opening addition polymerization, a method in which the above-mentioned monomer is ring-opened and added in an appropriate solvent (mineral oil, xylene, etc.) in the presence of a polymerization catalyst and water, if necessary. Examples of the addition catalyst used for the above ring-opening addition include anion addition polymerization catalysts (for example, hydroxides of alkali metals such as sodium hydroxide, potassium hydroxide, and cesium hydroxide; methoxy sodium, sodium butoxy, methoxy potassium, Alkali metal alcoholate compounds such as potassium butoxy; alkylamines such as tetrabutylamine); cation addition polymerization catalysts (eg, aluminum,
Chlorides such as antimony, boron, phosphorus, iron, zinc, titanium;
Combination of a mineral acid such as hydrochloric acid, bromic acid, sulfuric acid, and perchloric acid), a coordination anion addition polymerization catalyst (for example, a metal alcohol or an alkaline earth metal compound such as triethoxy iron, and an active hydrogen compound such as acetylacetone or a Lewis acid) Etc.)
Is mentioned. From the viewpoint of economy and productivity, production using an anion addition polymerization catalyst is preferred. In the production of (A) by anionic polymerization, the compound (a) containing the active hydrogen is used.
And heating the polymerization catalyst while reacting the above monomers. The reaction temperature is 40 to 1
The temperature is 50 ° C, preferably 90 to 130 ° C.

In addition, in the production of (A), since the ring-opening addition polymerization is a sequential addition reaction, the addition polymerization reaction may be interrupted at the stage when a product having an arbitrary number average molecular weight is produced, Once the product is taken out and purified, the purified product can be used as a starting material for further addition polymerization to obtain the desired number average molecular weight.

In the present invention, (A) includes those obtained by ring-opening addition polymerization of the above-mentioned monomers and those obtained by further modifying the terminal thereof. Further, (A) also includes those obtained by joining a ring-opening addition polymer of the above-mentioned monomer or a modified product thereof and a ring-opening addition polymer produced by ring-opening addition-polymerization of the above monomer to have a high molecular weight. It is.

In the present invention, when the terminal of (A) is further modified, the terminal may be modified by an esterification reaction of a terminal hydroxyl group or thiol group with an organic acid, an inorganic acid or a derivative thereof, a compound containing an isocyanate group. And etherification by a desalination reaction with a halogenated hydrocarbon after converting the terminal group into an alcoholate or thiolate with an alkali metal first.

The compounds used for the above modification include the following. (1) Organic acids and their ester-forming derivatives; aliphatic monocarboxylic acids having 1 to 12 carbon atoms (acetic acid, propionic acid, butyric acid, lauric acid, etc.), aromatic monocarboxylic acids having 7 to 16 carbon atoms (benzoic acid) Acid, cinnamic acid, naphthyl acid, etc.) and their acid anhydrides, acid halides, etc. (2) Inorganic acids; sulfuric acid, chlorosulfonic acid, sulfan, sulfamic acid, thionyl chloride, phosphoric anhydride, etc. ) Isocyanate group-containing compounds; aromatic polyisocyanates having 6 to 20 carbon atoms (excluding carbon in the NCO group, the same applies hereinafter) [1,3- and / or 1,4-phenylene diisocyanate, 2,4- and / or 2,6-tolylene diisocyanate, 2,4'- and / or 4,4'-diphenylmethane diisocyanate, etc.],
Aliphatic polyisocyanate having 2 to 18 carbon atoms [ethylene diisocyanate, tetramethylene diisocyanate,
Hexamethylene diisocyanate, etc.], having 4 to 1 carbon atoms
5 alicyclic polyisocyanates [isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, etc.], having 8 to 8 carbon atoms
15 araliphatic polyisocyanates [m- and / or p-xylylene diisocyanate, α, α, α ′,
α′-tetramethylxylylene diisocyanate] and modified products of these polyisocyanates (urethane group, carbodiimide group, allophanate group, urea group, buret group, uretdione group, uretoimine group, isocyanurate group, oxazolidone group-containing modification) And mixtures of two or more of these. (4) alkali metals and halogenated hydrocarbons; as alkali metals, sodium, potassium and lithium,
As the halogenated hydrocarbon, a halogen (chlorine, bromine, fluorine) compound having a linear or branched alkyl group or aralkyl group having 1 to 18 carbon atoms, for example, methyl chloride, ethyl chloride, methyl bromide, octyl chloride, Lauryl chloride, benzyl chloride, etc.

Examples of the joint reaction include a polyesterification reaction of (A) with a modified product obtained by modifying the terminal of (A) with carboxylic acid, or a (poly) esterification reaction of a polycarboxylic acid compound with (A). (Poly) urethanization reaction of the above polyisocyanate or polyalkylene (thio) ether modified with terminal polyisocyanate with (A), ring-opening addition reaction of polyalkylene (thio) ether of terminal polyepoxide with (A), dihalogen Condensation reaction of two or more molecules of polyalkylene (thio) ether (thio) alcoholate with a fluorinated hydrocarbon.

The modified polycarboxylic acid compound obtained by modifying the terminal with a carboxylic acid used in the joint reaction includes:
(A) and a monohalogenated fatty acid (for example, monochloroacetic acid, monobromoacetic acid, monochloropropionic acid, etc.), and a terminal carboxyalkylated product thereof, and ester-forming derivatives thereof (acid anhydride, lower alkyl ester, acid) Halides).

Examples of the polycarboxylic acid compound used in the joint reaction include aliphatic dicarboxylic acids having 2 to 40 carbon atoms, such as oxalic acid, malonic acid, succinic acid, adipic acid, azelaic acid and dimer acid. 24 aromatic polycarboxylic acids such as phthalic acid, terephthalic acid, trimellitic acid and the like, and their ester-forming derivatives (acid anhydrides, lower alkyl esters, acid halides and the like).

Examples of the dihalogenated hydrocarbon used in the joint reaction include alkylene dihalides having 1 to 6 carbon atoms (dichloromethane, dibromomethane, chromium bromomethane, dichloroethane, dibromoethane, dichlorobutane, etc.).

The (A) of the present invention has a number average molecular weight of 11,
000-250,000, preferably 17,000-2
00,000, more preferably 20,000 to 15
It is 0000. If the number average molecular weight is less than 11,000, the viscosity increase is small, and if it exceeds 250,000, the shear stability becomes poor. The number average molecular weight is measured by gel permeation chromatography, and is obtained by converting to polystyrene.

In the present invention (A), the average value of the solubility parameter of the whole molecule is 8.6 to 9.4, preferably 8.8.
To 9.3, more preferably 8.8 to 9.2, and if the solubility parameter is less than 8.6, the viscosity index deteriorates,
If it exceeds 9.4, the solubility in the base oil deteriorates.

The polymer (A) of the present invention has a crystallization onset temperature of -15 ° C or lower, preferably -20 ° C or lower, more preferably -25 ° C or lower, as measured by a differential scanning calorimeter. If the temperature exceeds -15 ° C, the viscosity increases at a low temperature, which adversely affects the low-temperature characteristics. The crystallization onset temperature by the differential scanning calorimeter of the present invention is UNIX DSC manufactured by PERKIN-ELMER.
7, 5 mg of a viscosity index improver was used as a sample, and 10 ° C.
Crystallization onset temperature observed when cooling from 140 ° C. to −75 ° C. at an isothermal rate per minute.

Further, when the polymer (A) of the present invention has a steric hindrance factor (F) ｛copolymer composition represented by the following general formula, the average value based on the mole fraction of the constituent monomers is used. ｝ Is 12 or less, preferably 8 or less, more preferably 5 or less, and particularly preferably 0. F = 4x + y {6 from the main chain contained in the side chain in the constituent monomer unit
Let x be the total number of atoms and y be the total number of atoms.と If the average value of steric hindrance factor (F) exceeds 12,
The steric hindrance around the main chain becomes large, and it tends to be difficult to shrink at low temperatures and the viscosity at low temperatures tends to be high.

The steric hindrance factor (F) is defined as the monomer unit constituting the polyalkylene (thio) ether moiety of (A), where the main chain atom to which the side chain is bonded is the 0th atom. The total number of atoms (x) (irrespective of the type of atom) at the sixth count in the direction is multiplied by 4 and the sum of the total number of atoms (y) at the seventh (irrespective of the type of atom) is obtained. The steric hindrance factor (F) expresses the size of the steric hindrance of the side chain as viewed from the polymer main chain for convenience, and the steric hindrance increases as the number increases. A calculation example is as follows. The numbers on the right of the atoms indicate the order of the atoms from the main chain. When there are a plurality of side chains, the total sum calculated for them is defined as (F).

Example a) In the case of a homopolymer of 1,2-heptene oxide

[0026]

Embedded image

6th atom number = 3 7th atom number = 0 Sterile hindrance factor (F) of constituent monomer = 4 × 3 + 0 =
12

When the polyalkylene (thio) ether moiety of (A) is composed of two or more kinds of monomers, the steric hindrance factor (F) calculated from each of the constituent monomer units is used to obtain the same. The average value of the steric hindrance factor (F) is determined by calculating the average value based on the mole fraction of the monomer units constituting the polymer.

Example b) 1,2-butylene oxide and 1,2
In the case of 75/25 (molar ratio) of 2-octene oxide

[0030]

Embedded image

Sixth atom number = 0 Sixth atom number = 3 Seventh atom number = 0 Seventh atom number = 3 Steric hindrance of constituent monomer Sterile hindrance of constituent monomer 0 × 4 + 0 = 0 Factor (F) = 4 × 3 + 3 = 15 Steric hindrance factor (F) = 0 × 0.75 + 12 × 0.25 = 3

The HLB value of (A) is preferably from 0.5 to 6.0, more preferably from 1.0 to 5.5, and particularly preferably from 1.5 to 5.0. When the HLB value is in the range of 0.5 to 6.0, the demulsifying property is particularly good. H of the present invention
The LB value is a value calculated by the HLB calculation formula of Griffin (“Introduction to New Surfactants”, P128, published by Sanyo Chemical Industries, Ltd.).

The viscosity index improver of the present invention further comprises, in addition to (A), an alkyl (meth) acrylate (b1)
May be used in combination with the polymer (B) having as an essential constituent monomer.

Specific examples of the alkyl (meth) acrylate (b1) which is an essential constituent monomer of the polymer (B) include:
(Meth) acrylates (b11) in which the alkyl group is a straight-chain or branched alkyl group having 1 to 6 carbon atoms, and (meth) acrylates in which the alkyl group is a straight-chain or branched alkyl group having 7 to 24 carbon atoms ( b12), and (b1)
Examples of the alkyl group of 1) include a methyl group, an ethyl group, and n-
And iso-propyl groups, n-, iso-, sec- and t-
Butyl group, n-, iso-, sec- and neopentyl group,
Examples of the alkyl group of (b12) such as a hexyl group include a heptyl group, n- and iso-octyl groups, a 2-ethylhexyl group, n- and iso-nonyl groups, n- and iso- groups.
Decyl, n- and iso-dodecyl, n- and iso
-Tridecyl, n- and iso-tetradecyl, n
-And iso-pentadecyl groups, n- and iso-hexadecyl groups, and n- and iso-octadecyl groups.

As the polymer (B), there may be mentioned these homopolymers and copolymers comprising two or more kinds as constituent monomers. Of (b1) used in (B), the molar ratio (b11) / (b12) of (b11) and (b12) is usually 0 /
100 to 55/45, preferably 0/100 to 4
0/60.

As the structural unit of the polymer (B), other than the alkyl (meth) acrylate, another copolymerizable vinyl monomer (b2) may be used. (B2) includes those having a nitrogen atom (b21) and those having no nitrogen atom (b2).
2) is included. Examples of these include:

As (b21), (b211) a vinyl monomer containing a nitrogen atom; N-vinylpyrrolidone, vinylpyridine, N, N-dialkylaminoalkyl (meth) acrylate (the alkyl group usually has 1 carbon atom) ~
4), N, N-dialkylaminoalkyl (meth) acrylamide (the alkyl group usually has 1 to 4 carbon atoms), vinylimidazole, morpholinoalkylene (meth) acrylate, etc.

(B212) a vinyl monomer containing a nitrogen atom and a sulfur atom; aminophenothiazine, N-
Arylphenylenediamine, aminocarbazole, aminothiazole, aminoindole, aminopyrrole,
Aminoimidazoline, aminomercaptothiazole, (meth) acrylate derivative having aminopiperidine residue, N-vinylthiopyrrolidone, etc.

As (b22), (b221) (poly) alkylene glycol [(poly) alkylene glycol represents alkylene glycol and / or polyalkylene glycol. Hereinafter, the same expression is used. Or a mono (meth) acrylate of a monoalkyl ether thereof; the monomers constituting the (poly) alkylene glycol are the same as the above-mentioned monomers constituting the polyalkylene (thio) ether moiety; Examples of the alkyl group constituting the monoalkyl ether include the aforementioned alkyl groups. The polymerization degree (number of oxyalkylene units) of the alkylene glycol in the (poly) alkylene glycol is usually from 1 to 50, preferably from 1 to 20, and the number average molecular weight is usually from 62 to 2,000, preferably from 62 to 1,000. . Mono (meth) of (poly) alkylene glycol or its monoalkyl ether
Specific examples of the acrylate include polyethylene glycol (degree of polymerization = 9) monomethacrylate, polyethylene glycol (degree of polymerization = 18) monomethacrylate,
Polypropylene glycol (degree of polymerization = 3) monomethacrylate, polyethylene glycol, (degree of polymerization = 6) monomethyl ether monomethacrylate, ethylene glycol mono-2-ethylhexyl ether monomethacrylate, polypropylene glycol (degree of polymerization = 3) monobutyl ether monomethacrylate, etc. No.

(B222) Mono (meth) acrylate of glycidyl ether polymer; glycidyl ether polymer constituting mono (meth) acrylate of glycidyl ether polymer includes alkyl groups having 1 to 12 carbon atoms. And a polymer obtained by ring-opening polymerization of a glycidyl group of an alkyl glycidyl ether having an alkenyl group or an aromatic ring, an alkenyl glycidyl ether or an aromatic glycidyl ether. Examples of the alkyl glycidyl ether include ethyl glycidyl ether, n-propyl glycidyl ether, n- and iso-butyl glycidyl ether, n-hexyl glycidyl ether, 2-ethylhexyl glycidyl ether, and the like.Alkenyl glycidyl ethers include allyl glycidyl ether. Examples of aromatic glycidyl ethers such as methallyl glycidyl ether and propenyl glycidyl ether include phenyl glycidyl ether. The number of glycidyl ether units of the poly (glycidyl ether) is usually 1 to 30, preferably 1
And the number average molecular weight is usually from 60 to 2,000, preferably from 60 to 1,000.

(B223) Fatty acid vinyl ester: a fatty acid vinyl ester having an alkyl group (linear or branched alkyl group) in the fatty acid having 1 to 30, preferably 1 to 22, and more preferably 1 to 10 carbon atoms. And
Examples of the alkyl group include the aforementioned alkyl groups.
Specific examples include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl hexanoate, vinyl heptanoate, vinyl 2-ethylhexanoate, and vinyl n-octanoate.

(B224) Alkyl esters of unsaturated mono- and / or polycarboxylic acids (crotonic acid, maleic acid, fumaric acid, itaconic acid, etc.) other than alkyl (meth) acrylate (C1-C30 alkyl group) ;
For example, butyl crotonate, octyl crotonate,
Dodecyl rotonate, dibutyl maleate, dioctyl fumarate, dilauryl maleate, distearyl fumarate, dioctyl itaconate, dilauryl itaconate, and the like.

(B225) Aliphatic vinyl hydrocarbons; alkenes having 2 to 18 carbon atoms [ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene and octadecene, etc.]; Alkadiene [butadiene, isoprene,
1,4-pentadiene, 1,6-hexadiene, 1,7-octadiene and the like].

(B226) Alicyclic vinyl hydrocarbons such as cyclohexene, (di) cyclopentadiene, pinene, limonene, indene, vinylcyclohexene and ethylidenebicycloheptene, etc.

(B227) aromatic vinyl hydrocarbons; styrene, substituted styrene [α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, ethylstyrene,
Isopropylstyrene, butylstyrene, phenylstyrene, cyclohexylstyrene, benzylstyrene, crotylbenzene, etc.], divinyl-substituted aromatic hydrocarbons [divinylbenzene, divinyltoluene, divinylxylene, etc.], vinylnaphthalene, etc.

(B228) alkyl vinyl ethers, alkyl allyl ethers, vinyl ketones;
Alkyl vinyl ethers having two alkyl groups [methyl vinyl ether, ethyl vinyl ether, n- and
iso-propyl vinyl ether, butyl vinyl ether, 2-ethylhexyl vinyl ether, etc.], alkyl (meth) allyl ether having a linear or branched alkyl group having 1 to 18 carbon atoms [methyl allyl ether, ethyl allyl ether, propyl allyl ether, butyl allyl Ether, amyl allyl ether, hexyl allyl ether, heptyl allyl ether, octyl allyl ether, nonyl allyl ether, decyl allyl ether, dodecyl allyl ether, tridecyl allyl ether, tetradecyl allyl ether, pentadecyl allyl ether, hexadecyl allyl ether, Octadecyl allyl ether and the like and methallyl ether corresponding thereto], and having an alkyl group or an aryl group having 1 to 8 carbon atoms. Niruketon [methyl vinyl ketone, ethyl vinyl ketone and phenyl vinyl ketone], etc.

(B229) Carboxyl group-containing vinyl monomers and salts thereof; monocarboxyl group-containing vinyl monomers [(meth) acrylic acid, monoalkyl maleate (C1-18) ester, monoalkyl fumarate (C1 -18) esters, monoalkyl itaconate (C1-18) esters, crotonic acid, cinnamic acid, etc.], dicarboxylic group-containing vinyl monomers [(anhydrous) maleic acid, fumaric acid, itaconic acid, etc.], tri or tetra The above carboxyl group-containing vinyl monomers [citraconic acid and aconitic acid and the like];
Alkali metal salts (such as sodium salts and potassium salts), alkaline earth metal salts (such as calcium salts and magnesium salts), amine salts and ammonium salts thereof

(B2210) hydroxyl group-containing vinyl monomer; hydroxystyrene, (meth) allyl alcohol, crotyl alcohol, isocrotyl alcohol, 1
-Buten-3-ol, 2-buten-1-ol, 2-
Butene-1,4-diol, propargyl alcohol,
2-hydroxyethylpropenyl ether, sucrose allyl ether and the like.

In the polymer (B) containing alkyl (meth) acrylate as an essential constituent monomer, the weight ratio of the constituent monomers is usually (b1) / (b2) = 100 / 0-30.
/ 70, preferably 95/5 to 60/40. (B
Of (2), the use of (b21) is preferable because it can impart clean dispersibility, antioxidant property, and the like. in this case,
The total weight ratio of (b21) in (B) is usually 0.1 to 10% by weight, preferably 0.2 to 0.2% by weight of the weight of (B).
5% by weight, and usually 0.5 to 5% by weight of (b2).
50% by weight.

The copolymer (B) in the present invention can be obtained by a usual method. For example, it can be obtained by radical polymerization of the above monomers in a solvent such as mineral oil. In this case, an azo-based polymerization catalyst (for example,
Azobisisobutyronitrile, azobisvaleronitrile, etc.) and peroxides (eg, benzoyl peroxide, cumyl peroxide, lauryl peroxide, etc.)
Can be used. When (B) is a copolymer,
Any of random, block, and graft copolymers may be used. The number average molecular weight of (B) is usually 5,000 to 50.
000, preferably 1,000 to 300,0
00.

When (A) and (B) of the present invention are used in combination, the amount of (B) is usually 0 to 100 parts by weight of (A).
100 parts by weight, preferably 0.05 to 50 parts by weight.

The base oil to which the viscosity index improver of the present invention is added has a kinematic viscosity at 100 ° C. of 1 to 6 mm ² / s,
Particularly, a base oil of 1.5 to ⁵ mm ² / s is preferable. When added to a base oil having a kinematic viscosity of 1 to 6 mm ² / s, the lubricating oil produced has better low-temperature properties.

The cloud point (JIS K2269) of the base oil using the viscosity index improver of the present invention is preferably −5 ° C. or less.
Preferably it is -15C or less. When the cloud point of the base oil is in this range, the amount of wax precipitated is small, and the low-temperature viscosity is more excellent. Examples of base oils include solvent refined oils, oils containing isoparaffins and / or high viscosity index oils (viscosity index = 70-150) by hydrocracking, hydrocarbon-based synthetic lubricating oils obtained by low polymerization of α-olefins, Examples include ester-based synthetic lubricating oils and naphthenic oils obtained by esterification of chain fatty acids with polyhydric alcohols.

The viscosity index improver of the present invention is usually added in an amount of 1 to 30% by weight based on the base oil as (A), and as the lubricating oil of the present invention, engine oil, gear oil, ATF (Automatic Transmission Fluid) ), CVT (continuously valuable transmission) oil (belt type, toroidal type), traction oil,
It can be suitably used for shock absorber oil or power steering oil. The addition amount is 1 to 1 in the case of engine oil.
0% by weight, gear oil, ATF and CVT oil (belt type)
Particularly preferred results are obtained in the range of 5 to 25% by weight in the case of (C) and 0.4 to 10% by weight in the case of CVT oil (toroidal type).

The viscosity index improver of the present invention may contain other optional components. Examples of other optional components include the following, and the total weight of these optional components is usually 1 to 20% by weight based on the total weight of the lubricating oil composition, and in the case of an engine oil, preferably 1 to 10% by weight. In the case of gear oil, it is preferably 5 to 20% by weight. Detergents (sulfonate, salicylate, phenate, naphthenate, etc.) Dispersants [alkenyl succinic acid (such as isobutenyl succinimide) etc.], antioxidants (zinc dithiophosphate, amine,
Hindered phenols), oiliness improvers (fatty acids, fatty acid esters, etc.), friction and wear modifiers (molybdenum dithiophosphate,
Molybdenum carbamate, zinc dithiophosphate, etc.), extreme pressure agent (sulfur phosphorus, chlor, etc.),

[0056]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. In Examples and Comparative Examples,% and parts represent% by weight and parts by weight. (Method of measuring weight average molecular weight by GPC) Apparatus: HLC-802A manufactured by Toyo Soda Column: 2 pieces of TSK gel GMH6 Measurement temperature: 40 ° C. Sample solution: 0.5% by weight THF solution Solution injection amount: 200 μl Detector: Refraction Rate detector Standard: Polystyrene

(Test Method for Kinematic Viscosity) JIS K2283
Was measured at 100 ° C.

(Test Method for Low Temperature Viscosity) JPI-5S-2
The viscosity at -25 ° C was measured by the method of 6-99.

Production Example 1 A pressure-resistant reaction vessel equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen inlet was charged with 100 parts of xylene and 1.20 parts of potassium hydroxide as an addition polymerization catalyst. After replacing the air with nitrogen gas, the mixture was heated at a reaction temperature of 125 ° C. for 5 hours. After dehydration, 1.8 parts of water and 10% by weight of an alkylene oxide mixture (ao1) in an amount shown in Table 1 were added dropwise.
The reaction was performed at a reaction temperature of 125 ° C. for 3 hours. This was repeated 10 times, and after the reaction was completed, the mixture was cooled to 60 ° C., and 90% of the obtained polyalkylene ether was taken out of the reaction vessel, and only 10% was left in the reaction vessel. In the reaction vessel,
Further, 100 parts of xylene and 1.20 parts of potassium hydroxide as an addition catalyst were charged, and an alkylene oxide mixture (ao2) was dropped and reacted under the same reaction conditions as described above. After the completion of the reaction, the reaction solution was cooled to 60 ° C., the reaction solution was neutralized with hydrochloric acid to pH 7.0, and filtered to remove a neutralized product of the additional catalyst. Thereafter, the temperature was raised to 130 ° C. under normal pressure, and when the temperature reached 130 ° C., the pressure was changed to reduced pressure. Was.

Production Examples 2 and 3 Polymers A2 and A3 of the present invention were obtained in the same manner as in Production Example 1 except that the alkylene oxides (ao1) and (ao2) were changed as shown in Table 1.

Production Example 4 To a reaction vessel equipped with a stirrer, a heating device, a thermometer, and a nitrogen blowing tube, 28 parts of toluene was charged, and a nitrogen atmosphere was prepared.
0 ° C. While stirring the inside of the reaction vessel, a solution consisting of 237.5 parts of n-dodecyl methacrylate and 12.5 parts of methyl methacrylate,
2′-azobis-2,4-dimethylvaleronitrile
A solution in which 5 parts and 1.9 parts of dodecyl mercaptan were dissolved was charged at a constant rate over 2 hours from separate dropping funnels, and the mixture was aged at 85 ° C. for 2 hours after the completion of the charging to carry out a polymerization reaction. After completion of the reaction, toluene was removed under reduced pressure at 130 ° C. to obtain an alkyl methacrylate polymer B1 having a number average molecular weight of 17,200.

Comparative Production Examples 1 to 4 The ratios A1 and A2 of the polymer of the comparative example were obtained in the same manner as in Production Example 1 except that the alkylene oxides (ao1) and (ao2) were changed as shown in Table 1. .

[0063]

[Table 1]

Table 2 shows the number average molecular weight, solubility parameter, crystallization onset temperature, steric hindrance factor and HLB value of the polymers A1 to B3 and the comparative polymer ratios A1 and A2.
It was shown to.

[0065]

[Table 2]

Examples 1 to 4 and Comparative Examples 1 to 3 Using the polymers A1 to A3 and B1 and the ratios A1 to 2, lubricating oil compositions were prepared as described below. And Comparative Examples 1 and 2.

A viscosity index improver comprising the polymer shown in Table 3 was used in a solvent refined oil (cloud point: kinematic viscosity at -20.0 ° C., 100 ° C.
Dissolve in 4.5 mm ² / s) to make lubricating oil. Then, the kinematic viscosity at 100 ° C. of the lubricating oil is 14.0 to 14.4 (mm ² /
The concentration of the viscosity index improver was adjusted so as to satisfy s) to obtain a test lubricating oil composition.

[0068]

[Table 3]

Table 3. As can be seen from Examples 1, 2 and 3, Examples 1 to 4 using the viscosity index improver of the present invention have a higher viscosity index and better solubility than Comparative Examples 1 to 3.

[0070]

The lubricating oil using the viscosity index improver of the present invention is different from the lubricating oil using the conventional viscosity index improver.
It is possible to provide an excellent lubricating oil having a high viscosity index and capable of meeting future demands for fuel economy of automobiles. further,
The viscosity index improver of the present invention is extremely useful because it has a flexible ether bond in the main chain and also has excellent shear stability in addition to the above characteristics.

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) // C10N 20:00 C10N 20:00 AZ 20:02 20:02 20:04 20:04 30:02 30:02 30:06 30:06 40:04 40:04 40:08 40:08 40:25 40:25

Claims (7)

[Claims] 1. A viscosity index improver comprising an oil-soluble polyalkylene (thio) ether or a derivative (A) thereof satisfying the following (i) to (iv) and the formula (1). (I) the number average molecular weight is 11,000 to 250,000 (ii) the solubility parameter is 8.6 to 9.4 (iii) the crystallization onset temperature by differential scanning calorimetry is -15
° C or less (iv) Sterile hindrance factor (F) is 12 or less R-Z-[(YZ) q- (XZ) p- (YZ) q] s-R (1) X is an alkylene group having a solubility parameter of (XZ) p of 8.650 or more; Y is (YZ) q
P is an alkylene group having a solubility parameter of less than 8.650, and (XZ) p and (YZ) q are each composed of a random copolymer; Z is an O or S atom; p And q are integers of 2 or more, s is an integer of 1 or more, and the number average molecular weight of (A) is 11,00.
R is H, a hydrocarbyl group having 1 to 18 carbon atoms, and a carbon atom having 1 to 18 carbon atoms.
Represents one or more groups selected from the group consisting of acyl groups of 2. The monomer constituting the polyalkylene (thio) ether moiety of (A) has an average carbon number of 2.2 to 6.2.
The viscosity index improver according to claim 1, which is: 3. The viscosity index improver according to claim 1, which comprises at least 50% by weight of 1,2-butylene oxide among the monomers constituting the polyalkylene (thio) ether moiety of (A). 4. The viscosity index improver according to claim 1, wherein the HLB value of (A) is 0.5 to 6.0. 5. The viscosity index improver according to claim 1, further comprising a polymer (B) containing alkyl (meth) acrylate as an essential constituent monomer. 6. A kinematic viscosity at 100 ° C. of 1 to 6 mm ²
A lubricating oil composition comprising a base oil having a C / s and a cloud point of −5 ° C. or lower and a viscosity index improver according to claim 1. 7. The base oil is engine oil, gear oil, ATF, C
The lubricating oil composition according to claim 6, which is a VT oil, a traction oil, a shock absorber oil or a power steering oil.