JP2754340B2 - Viscosity index improver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a viscosity index improver. More particularly, it relates to a viscosity index improver for high viscosity index mineral oil containing isomerized paraffin.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand for lubricating oils and hydraulic oils to have low-temperature viscosities in response to recent social demands for fuel efficiency. As one means for solving this problem, a high viscosity index oil containing isomerized paraffin, or a combination thereof with an ordinary solvent-refined mineral oil, synthetic lubricating oil, or MLDW oil is being used. On the other hand, attempts have been made to improve the low temperature viscosity by using a pour point depressant. Examples of this are found in JP-A-54-70305, and a viscosity index improver suitable for the present high viscosity index oil is demanded. On the other hand, viscosity index improvers in which acrylate is positively copolymerized with methacrylate are known. An example of this is disclosed in JP-A-47-12982. However, although this publication describes that it relates to an engine oil using a general solvent-refined mineral oil having a viscosity index of about 100, it does not disclose its use for a high viscosity index oil containing isomerized paraffin. Further, there is no disclosure of using a high viscosity index oil to provide a lubricating oil or a hydraulic oil having a low low-temperature viscosity. At the time of filing the publication, no high viscosity index oil was used, and it was natural that no mention was made of making the low temperature viscosity extremely low.

[0003]

SUMMARY OF THE INVENTION The present invention relates to an improved viscosity index which gives an excellent low-temperature viscosity when used in a high viscosity index oil having a composition significantly different from that of ordinary mineral oils. Develop agents.

[0004]

DISCLOSURE OF THE INVENTION As a result of intensive studies, the present inventors have surprisingly unexpectedly found that a conventionally known polymer has an extremely low low-temperature viscosity when used in a high viscosity index oil which has recently been used. It has been found that the present invention has been made, and the present invention has been achieved. The present invention relates to a high viscosity index oil containing isomerized paraffin, comprising a polymer (A) containing 20 to 70% by weight of an alkyl acrylate (a1) and 80 to 30% by weight of an alkyl methacrylate (b1) as constituent units. For improving viscosity index.

The alkyl acrylate (a1) used in the present invention is an acrylate having a linear or branched alkyl group having 1 to 22 carbon atoms in the alkyl group. Examples of these include methyl acrylate, ethyl acrylate, isopropyl acrylate,
n-butyl acrylate, s-butyl acrylate, t
-Butyl acrylate, pentyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, i
-Decyl acrylate, dodecyl acrylate, tetradecyl acrylate, pentadecyl acrylate, cetyl acrylate, octadecyl acrylate and the like. Among these various acrylates, those having an alkyl group having 10 or less carbon atoms are preferable from the viewpoint of providing a lubricating oil having a low-temperature viscosity and the like, and in particular, an acrylate having an alkyl group having 1 to 4 carbon atoms, It is preferable to use an acrylate having 10 alkyl groups in combination, or to use only an acrylate having an alkyl group having 5 to 10 carbon atoms. More preferred are octyl acrylate and 2-ethylhexyl acrylate having an alkyl group having 8 carbon atoms.

[0006] The alkyl methacrylate (b1) used in the present invention usually has 1 to 22 carbon atoms, and examples thereof include methacrylates having the same acrylate alkyl group. Among these various methacrylates, preferred are methacrylates having an alkyl group having 10 or more carbon atoms, and particularly preferably those having 1 to 4 carbon atoms in the alkyl group relative to the total amount of the methacrylate. % By weight, 10 to 65% by weight of an alkyl group having 12 to 13 carbon atoms, 10 to 65% by weight of an alkyl group having 14 to 15 carbon atoms, and 0 to 0% by weight of an alkyl group having 16 to 18 carbon atoms. The case is 30% by weight.

The copolymerization ratio of the alkyl acrylate (a1) and the alkyl methacrylate (b1) has a preferable range. From the viewpoint of low-temperature viscosity characteristics (a1):
(B1) is generally preferred when it is in the range of 20-70: 80-30, particularly preferably in the range of 30-60: 70-40.

[0008] The viscosity index improver of the present invention has a preferred molecular weight. Usually, the weight average molecular weight (Mw) needs to be in the range of 1 to 500,000. If it is less than 10,000, the thickening effect is insufficient, and if it exceeds 500,000, the shear stability becomes poor.
When used for drive system lubricating oil (manual transmission oil, differential gear oil, automatic transmission oil, etc.), Mw is preferably 2
When used for hydraulic oil (hydraulic oil for construction machinery, power steering oil, shock absorber oil, etc.), Mw is preferably in the range of 30,000 to 200,000, and engine oil (for gasoline, When used for diesel applications, etc.), it is when Mw is in the range of 130,000 to 500,000. The molecular weight is a value obtained by GPC using polystyrene as a calibration curve.

The viscosity index improver of the present invention is a copolymer comprising an alkyl acrylate and an alkyl methacrylate. If necessary, the viscosity index improver may have at least one atom selected from a nitrogen atom, an oxygen atom and a sulfur atom. It may be a polymer containing at least one monomer. Examples of the introduction method include random copolymerization, graft copolymerization, and graft addition.
In this case, the viscosity index improver is preferable because it can impart clean dispersibility, antioxidant property, and the like. An example of this is USP50
13468, USP 50113470, EP50801
2, USP 4606834, USP 4036766, U
SP40367768, USP4904404, USP4
812621, USP4668412, USP4790
948, US Pat. No. 4,795,577, JP-A-60-1107
90, JP-A-61-247719, JP-A-63-514
97, JP-A-63-179999, JP-A-01-193
308, JP-A-01-284593, JP-A-62-14
1096, JP-A-02-296811, JP-A-04-2
11498 or the like can be used. As specific examples, random copolymerization and examples of compounds to be graft-copolymerized include N-vinylpyrrolidone and N-vinylpyrrolidone.
Vinylthiopyrrolidone, vinylpyridine, N, N-dialkylaminoalkylene (meth) acrylate (the alkyl group usually has 1 to 4 carbon atoms), N, N-dialkylaminoalkylene (meth) acrylamide (the carbon number of the alkyl group is Usually 1 to 4), vinylimidazole, morpholinoalkylene (meth) acrylate, etc., aminophenothiazine, N-arylphenylenediamine, aminocarbazole, aminothiazole, aminoindole,
Aminopyrrole, aminoimidazoline, aminomercaptothiazole, having aminopiperidine residue (meth)
Various types such as acrylate derivatives are exemplified. Also,
As an example of the compound to be graft-added, a small amount (for example, 0.5 to 5% by weight) of a carboxylic acid compound (maleic anhydride, methacrylic acid, crotonic acid, itaconic acid, etc.) is copolymerized during the copolymerization of acrylate and methacrylate. Examples thereof include those obtained by amidation and imidization with (poly) amines and those obtained by Mannich condensation of formaldehyde and (poly) amines. Furthermore, non-vinyl compounds (for example, phenothiazines, imidazoles, thiazoles, benzothiazoles, triazoles, thiazolindins, pyrimidines, piperazines, pyrrolidinones) can be obtained by using a radical catalyst or the like for the copolymer (A). Oxazoles, thiomorpholines, etc.). The amount of these various compounds in the polymer (A) is usually at most 20% by weight, preferably at most 10% by weight, particularly preferably at most 5% by weight.
% By weight or less.

In the present invention, in addition to (a1) and (b1), a polymerizable double bond other than (a1) and (b1) as a constituent unit of the polymer (A) is less than 30% by weight, preferably less than 20% by weight. Other compounds having the formula: Examples thereof include unsaturated mono- and / or polycarboxylic acid esters having 1 to 30 carbon atoms such as butyl crotonate, octyl crotonate, dodecyl crotonate, dibutyl maleate, dioctyl fumarate, dilauryl. Maleate, distearyl fumarate, dioctyl itaconate, dilauryl itaconate, etc.), vinyl aromatic compounds (styrene, vinyl toluene, etc.), vinyl ethers (methyl vinyl ether, butyl vinyl ether, etc.), vinyl esters (vinyl acetate, Vinyl propionate, etc.), alpha olefins (decene, dodecene, etc.) and the like.

The viscosity index improver of the present invention can be easily obtained by a usual method. For example, it can be obtained by radical polymerization of the above monomers in mineral oil or a solvent. In this case, an azo (for example, azobisisobutyronitrile, azobisvaleronitrile, etc.) or a peroxide (for example, benzoyl peroxide,
Cumyl peroxide, lauryl peroxide, etc.).

The viscosity index improver of the present invention preferably further contains a pour point depressant. As the pour point depressant, a conventionally known polymethacrylate can be used. For example, a methacrylate compound having an alkyl group having 10 to 20 carbon atoms, or a combination of two or more methacrylate compounds having different compositions and molecular weights (for example, described in JP-A-54-70305 and the like) And very high molecular weight (eg, US
P5229021) and the like. When the pour point depressant is contained, the polymer (A) 1
The pour point depressant is usually 30 parts by weight or less based on 00 parts by weight,
Preferably it is 20 parts by weight or less.

[0013] The isomerized paraffin-containing high viscosity index oil to which the viscosity index improver of the present invention is added is different from those produced by ordinary solvent refining in terms of both performance and composition. is there. This high viscosity index oil is disclosed in Netherlands Patent Application No. 7613854 and JP-A-5-2143.
49 and the like. That is, it contains a component obtained by hydrocracking n-paraffin using a catalyst and isomerizing to i-paraffin. A noble metal catalyst or the like is usually used as the hydrocracking catalyst at this time. Incidentally, the i-paraffin-containing isomerized mineral oil produced in this way, which is further subjected to solvent purification, is also included in the target mineral oil of the present invention. Such isomerized paraffin-containing mineral oil has a large difference in composition from ordinary solvent-refined mineral oil, and therefore has a large viscosity index, and usually varies from about 110 to 160, although it varies depending on the production method and i-paraffin content. (Normal mineral oil has a viscosity index of 90 to 10
5). Naturally, the viscosity index improver of the present invention can be used for an isomerized paraffin-containing high viscosity index oil alone.
The present invention also includes a case where it is mixed with an oil or the like. Here, ordinary mineral oil refers to vacuum distilled oil, degreasing oil, etc., after removing aromatic components with a solvent using furfural or the like, and then adding toluene / toluene.
Dewaxed with a mixed solvent of methyl ethyl ketone or propane. Synthetic lubricating oils include ester-based (such as esters of alcohols such as trimethylolpropane, pentaerythritol and hexamethylenediol and fatty acids, and esters of adipic acid and aliphatic alcohols) and polyolefin-based lubricants. (For example, PAO-based ones such as decene oligomer). The MLDW oil is produced by a process called Mobile Lube Dewaxing, and is specifically obtained by decomposing and removing wax with a synthetic zeolite catalyst or the like. The present invention also includes a case where a high viscosity index oil is used in combination with another oil. In this case, the content of the high viscosity index oil is about 100 to 30% by volume.

The viscosity index improver of the present invention is used together with a high viscosity index oil, and is optimal for an engine oil, a drive system lubricating oil, and a hydraulic oil. Of these, when used in driveline lubricating oils and hydraulic oils that are required to have low low-temperature viscosity,
The excellent effect is further exhibited and is preferable.

The viscosity index improver of the present invention may contain other optional components such as detergents (sulfonate, salicylate, phenate, naphthenate, etc.), dispersants (isobutenylsuccinimide, Mannich condensation). Substances), antioxidants (zinc dithiophosphate, amines, hindered phenols, etc.), oil agents (fatty acids,
Fatty acid ester type), friction and wear modifier (molybdenum dithiophosphate, molybdenum carbamate, etc.), and extreme pressure agent (sulfur phosphorus type, chlor type, etc.) may be included.

[0016]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified,% means% by weight.

Example 1 300 g of mineral oil was placed in a glass 1-liter reactor equipped with a stirrer, a thermometer, and a condenser, and the air in the reactor was replaced with nitrogen. While flowing a small amount of nitrogen, 90 g of 2-ethylhexyl acrylate as a monomer, 210 g of a mixture of dodecyl methacrylate and tridecyl methacrylate (manufactured from dovanol, hereinafter abbreviated as 12/13 MA), and 0.1 g of azobisvaleronitrile as a catalyst. A mixture of 9 g and 1.4 g of lauryl mercaptan as a chain transfer agent was added dropwise over 4 hours, and the temperature was kept at the same temperature for 3 hours to complete the polymerization.
As a result, a polymer having Mw of 38,000 and Mw / Mn of 1.9 having a polymer concentration of 49% was obtained.

Example 2 135 g of 2-ethylhexyl acrylate was used as a monomer.
g, polymerization was carried out in the same manner as in Example 1 except that 165 g of a mixture of tetradecyl methacrylate and pentadecyl methacrylate (manufactured from dovanol, hereinafter abbreviated as 14 / 15MA) was used, and Mw was 39,000, Mw
/ Mn 1.9, a polymer having a polymer concentration of 49% was obtained.

EXAMPLE 3 2-ethylhexyl acrylate as a monomer was 18
Polymerization was carried out in the same manner as in Example 1 except that 0 g and 120 g of tetradecyl methacrylate were used.
A polymer having a Mw / Mn of 2.0 and a polymer concentration of 49% was obtained.

Example 4 As a monomer, 2-ethylhexyl acrylate 135 was used.
g, 41 g of dodecyl methacrylate, 105 g of tetradecyl methacrylate, a 7: 3 mixture of cetyl methacrylate and octadecyl methacrylate (hereinafter 16 / 18M
(Abbreviated as A) Polymerization was carried out in the same manner as in Example 1 except that 19 g was used to obtain a polymer having a Mw of 37,000 and a Mw / Mn of 1.8 and a polymer concentration of 49%.

Example 5 Polymerization was carried out in the same manner as in Example 4 except that 30 g of butyl acrylate and 105 g of 2-ethylhexyl acrylate were used instead of 135 g of 2-ethylhexyl acrylate in the monomer. / Mn 1.9, a polymer having a polymer concentration of 49% was obtained.

Example 6 Polymerization was carried out in the same manner as in Example 4 except that 135 g of dodecyl acrylate was used instead of 135 g of 2-ethylhexyl acrylate.
A polymer having a polymer concentration of 1.7 and a polymer concentration of 49% was obtained.

Example 7 N-vinylpyrrolidone 3 was added to 200 g of the polymer of Example 4.
g, 1.8 g of dicumyl peroxide and 3 g of mineral oil were placed in a 1-liter glass reactor, and the air in the reactor was replaced with nitrogen. Then, the mixture was reacted at 150 C for 4 hours while stirring, and vinylpyrrolidone was grafted. Polymerized Mw 43,000, M
A polymer having a w / Mn of 2.4 and a polymer concentration of 50% was obtained.

Example 8 Example 4 except that lauryl mercaptan was not used.
Polymerization was carried out in the same manner as described above, and Mw 220,000, Mw / Mn
A polymer having a polymer concentration of 2.9 and a polymer concentration of 50% was obtained.

Comparative Example 1 As a monomer, methyl methacrylate (hereinafter abbreviated as MMA) 50 g, 12/13 MA 200 g, 16/18 MA
Polymerization was carried out in the same manner as in Example 1 except for using 50 g, and the polymer concentration of Mw 38,000 and Mw / Mn 1.9 was 4
9% of a polymer was obtained.

Comparative Example 2 As a monomer, 15 g of MMA, 200 g of 14/15 MA,
Polymerization was carried out in the same manner as in Example 1 except that 50 g of 16/18 MA was used to obtain a polymer having a Mw of 38,000 and a Mw / Mn of 1.9 having a polymer concentration of 49%.

Comparative Example 3 As monomers, 50 g of MMA, 95 g of 12/13 MA, 1
Polymerization was conducted in the same manner as in Example 1 except that 93 g of 4/15 MA and 62 g of 16/18 MA were used, and Mw was 3.9.
A polymer having a Mw / Mn of 1.8 and a polymer concentration of 49% was obtained.

Comparative Example 4 50 g of MMA, 75 g of 12/13 MA, 1
Polymerization was performed in the same manner as in Example 1 except that 113 g of 4/15 MA and 62 g of 16/18 MA were used, and Mw was 3.9.
A polymer having a Mw / Mn of 1.8 and a polymer concentration of 49% was obtained.

Comparative Example 5 Comparative Example 3 except that lauryl mercaptan was not used.
Polymerized in the same manner as described above, Mw 220,000, Mw / Mn 3.0
A polymer having a polymer concentration of 50% was obtained.

(Use Examples 1 to 7 and Comparative Use Examples 1 to 4) The polymers of Examples 1 to 7 and the polymers of Comparative Examples 1 to 4
7%, and 1% of Acrube 122 (manufactured by Sanyo Chemical Industry Co., Ltd.) as a pour point depressant, with high viscosity index oil A (viscosity index 1
23 (100 neutral oils) and high viscosity index oil B (100 neutral oils with a viscosity index of 138), respectively.
100 ° C required for automatic transmission oil
Was adjusted to 7.4 to 7.6 cSt. The viscosity at -40 ° C was measured, and the results shown in Table 1 were obtained. As is clear from Table 1, it is understood that the composition of the present invention has a low viscosity at low temperature.

[0031]

______________________________________ _______________________________________ Viscosity index improver | High viscosity index oil A | High------------------------------Viscosity index improver | Viscosity index oil B ------------------------------------------------------------ 1 | Example 1 | 21600 cps | 26500 cps | 2100 of Example 2 | 16100 | 20200 | 3 | Example of Example 3 | 18400 | 21000 Usage Example | 4 | Example of Example 4 | 14300 | 18600 | 5 | Example of Example 5 | 15200 | 19900 | 6 | of the sixth embodiment | 24700 | 27100 | 7 | of the seventh embodiment | 16200 | 19700 ------------------------------------ −−−−−−−− Comparison ｜ 1 ｜ Comparative Example 1 ｜ 52200 ｜ 35500 Example | 2 | Comparative Example 2 | 37700 | 36000 | 3 | Comparative Example 3 | 37500 | 42400 | 4 | Comparative Example 4 | 34400 | 38200--------------- −−−−−−−−−−−−−−−−−−−−−−−−−−

(Comparative Use Examples 5 to 15) In place of the high viscosity index oil, a conventional solvent refined mineral oil A (10 with a viscosity index of 101) was used.
0 neutral oil), solvent refined mineral oil B (viscosity index 98
Examples 1 to 7 and Comparative Examples 1 to
4 were added in the same manner as in Use Examples 1 to 7 and Comparative Use Examples 1 to 4, and the viscosity at −40 ° C. was measured.
As can be seen from Table 2, when ordinary mineral oil was used,
The low-temperature viscosities of Examples 1 to 7 and Comparative Examples 1 to 4 do not change much. This indicates that even when the same viscosity index improver is used between the high viscosity index oil and the ordinary mineral oil, the effect on the low temperature viscosity is considerably different.

[0033]

[Table 2]

(Use Example 8 and Comparative Use Example 16) Use Example 1
7 and 7% of the polymer of Example 8 and Comparative Example 5 were added to the high viscosity index oils A and B used in Comparative Use Examples 1 to 4 and Alube 133 (manufactured by Sanyo Chemical Industries, Ltd.) as a pour point depressant.
0.5% was added to adjust the 100C viscosity required for 10W / 30 engine oil to 10.2 to 10.6 cSt.
The CCS viscosity at 0 ° C. was measured and the results in Table 3 were obtained.

[0035]

______________________________________ ________________________________________ Viscosity index improver | High viscosity index oil A | High (Table 3)----------------------------------Viscosity index improver | Viscosity index oil B----------------------------------Use Example 8 | 3030 cps −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− Comparative usage example 16 | that of comparative example 5 | 4720 | 4520 − −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−

(Comparative Use Examples 17-18) Comparative Use Examples 5
The lubricating oil was prepared in the same manner as in Use Example 8 and Comparative Use Example 16 using the ordinary solvent-purified mineral oils A and B used in No. 15 and Table 4.
Was obtained.

[0037]

[Table 4]

(Use Example 9 and Comparative Use Example 19) Same as Use Examples 1 to 7 and Comparative Use Examples 1 to 4 except that those of Example 5 and Comparative Example 3 were used and no pour point depressant was used. The viscosity was measured at −40 ° C., and the results in Table 5 were obtained.

[0039]

______________________________________ Table 5: Viscosity index improver | High viscosity index oil A | High-------------------------------Viscosity index improver | Viscosity index oil B --------------------------------------------------------------------------------------------------------- Example 9 | Example 5 | 43100 cps | 51000 cps-------------------------------------Comparative usage example 19 | 100,000 or more -------------------------------------------------

(Use Examples 10 to 12 and Comparative Use Example 20)
Example 2, Example 4, Example 5, and Comparative Example 3 were used, and high viscosity index oil A: ordinary mineral oil A = 50 as a base oil:
Example 1 and Comparative Example 1 except that 50 (volume%; abbreviated as base oil A) and high viscosity index oil B: ordinary mineral oil B = 50: 50 (volume%; abbreviated as base oil B) Similarly, the viscosity was measured at -40 ° C, and the results shown in Table 6 were obtained.

[0041]

Table 6: Viscosity index improver | Base oil A | Base oil B |-----------------------------Viscosity index improver | −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− |||| 2 | 21000 cps | 27200 cps Example of use | 11 16800 | 20100 | 12 | Example 5 | 17300 | 21100------------------------------------------------------------------------------------ −−−−−− Comparative usage example | 20 | Comparative example 3 | 31700 | 36200 −−−−−−−−−−−−−−−−−−−−−−−−−−− −−−−−−

[0042]

As is clear from the above Examples and Comparative Examples, it is found that when the improver of the present invention is used for a high viscosity index oil, a very low viscosity at low temperature (-40 ° C.) is given.

────────────────────────────────────────────────── (5) Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI C10M 101: 02 145: 14) C10N 30:02 40:08 40:25 (56) References JP-A-54-70305 (JP, A) JP-A-4-277597 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C10M 145/14 C10N 30:02

Claims (6)

(57) [Claims] 1. High viscosity containing isomerized paraffin, comprising a polymer (A) containing 20 to 70% by weight of an alkyl acrylate (a1) and 80 to 30% by weight of an alkyl methacrylate (b1) as constituent units. Viscosity index improver for index oils. 2. The improver according to claim 1, wherein (a1) is an alkyl acrylate having an alkyl group having 10 or less carbon atoms. 3. An alkyl acrylate (a1-1) having an alkyl group having 1 to 4 carbon atoms, and an acrylate (a1-) having an alkyl group having 5 to 10 carbon atoms.
The improver according to claim 1 or 2, which is used in combination with (2) or (a1-2) alone. 4. The improver according to claim 3, wherein (a1-2) is an alkyl acrylate having an alkyl group having 8 carbon atoms. 5. The improver according to claim 1, further comprising a pour point depressant (B). 6. The improver according to claim 1, which is used for an engine oil, a drive system lubricating oil, or a hydraulic oil.