JPH0641572A - Lubricant oil composition - Google Patents

Abstract

PURPOSE:To provide the lubricant oil composition excellent in thermal oxidation stability and especially suitable for film-stretching machines. CONSTITUTION:The lubricant oil composition is produced by adding a phosphite or amine compound and a hindered phenolic additive having a mol.wt. of 500-1200 to a polyalkylene glycol lubricant base oil. A heat-resistant polyalkylene glycol oil is preferably also added, and th5 further addition of a hindered phenolic additive having a mol.wt. of 300-500 permits to especially reduces the production of sludges.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a lubricating oil composition,
More specifically, the present invention relates to a lubricating oil composition that has excellent oxidation stability and that does not easily generate sludge, and is suitable for use in a film stretching machine.

[0002]

2. Description of the Related Art For example, a lubricating oil suitable for use in a film stretching machine has not only high lubrication performance but also a high operating temperature range (usually 150 ° C. or higher), and therefore, thermal oxidation stability and low Evaporability is required, and further desired viscosity characteristics (high viscosity, high viscosity index, etc.) are also required.

Lubricating oils used in such fields are typically polyalkylene glycol (hereinafter abbreviated as PAG) -based or diphenyl ether-based base oils with additives added as necessary. Target.

The latter, that is, the diphenyl ether type base oil, shows extremely high performance with respect to thermo-oxidative stability, but it is not possible to obtain a highly viscous product, and the viscosity index is poor. There are drawbacks. Further, when used beyond the limit of thermo-oxidative stability of the base oil, it also has a drawback that the solidification residue of the base oil is larger than that of the PAG base oil.

On the other hand, the PAG base oil has a good viscosity index and a high viscosity product, the base oil itself has a high ability to dissolve a deteriorated product, and the thermal decomposition product has a low molecular weight. Since it becomes a volatile gas, there is an advantage that there is little concern that the device or the product (film or the like) is contaminated.

[0006]

However, the PAG type lubricating oil itself is inferior in thermal oxidation stability. Therefore, although improvement has been investigated by adding an oxidation stabilizer, sufficient performance has not been obtained so far.

An object of the present invention is to provide a lubricating oil composition having a high thermal oxidative stability and a small amount of sludge, which is particularly suitable for a film stretching machine.

[0008]

To achieve this, a particularly preferred embodiment of the lubricating oil composition of the present invention provides a PAG-based lubricating base oil (particularly a high viscosity / high viscosity suitable as a lubricating oil for film stretching machines and the like). PAG lubricant base oil showing viscosity index)
(1) A phosphite, (2) an amine compound, and (3) a lubricant having an average molecular weight of 500 or more and 1200 or less and a hindered phenol in combination to bring out a synergistic effect and further impart thermal oxidation stability. It is an oil composition.

Further, by adding (4) a hindered phenol having an average molecular weight of 300 or more and less than 500 to the above composition, a composition which produces a small amount of sludge is provided.

The PAG-based lubricating base oil used in the present invention will be described. The PAG-based lubricating base oil is a liquid substance mainly having a PAG structure and having the following structure.

R ₁ O- (R ₃ O) _n -R ₂ R ₁ , R ₂ : hydrogen or an alkyl group having 1 to 4 carbon atoms, which may be the same or different.

R ₃ is a ring-opening polymer or ring-opening copolymer of a linear or branched alkylene oxide having 2 to 18 carbon atoms.

Specific examples include polypropylene glycol and polybutylene glycol, and their monools, diols and diethers can be mentioned. The molecular weight range is 1000 to 8000, preferably 30.
It is the thing of 00-8000.

Another form of PAG-based lubricating base oil is a heat-resistant PAG-based lubricating base oil, which has the following structure.

[0015]

[Chemical 1]

R _{11 is} hydrogen or an alkyl group having 1 to 20 carbon atoms.

R ₁₂ : Ring-opening polymer or ring-opening copolymer of linear or branched alkylene oxide having 2 to 18 carbon atoms.

Specific examples include polypropylene oxide stearyl phenyl derivatives and polyethylene oxide stearyl phenyl derivatives. Also,
The molecular weight range is 200 to 1000, preferably 500 to 1.
000.

The above PAG-based lubricating base oil and the heat-resistant PAG-based lubricating base oil may be used alone or as a mixture. When mixing, a ratio of 9: 1 to 6: 4 is preferable from the viewpoint of viscosity characteristics and oxidative stability.

The viscosity of these base oils is 60 to 120 cSt.
(@ 100 ° C), preferably 90-100 cSt (@ 10
(0 ° C.) and a viscosity index of 200 or more, preferably 220 or more.

Next, the phosphite will be described.

Examples of the phosphite include those having the following structures.

[0023] _{(R 31 -O) 3 -P [} R 31: or a hydrocarbon group having 1 to 24 carbon atoms

[0024]

[Chemical 2]

It may be the same or different.

R ₃₂ represents hydrogen, an alkyl group having 1 to 24 carbon atoms or an alkylphenyl group] Specifically, triisooctyl phosphite, tris (2-ethylhexyl)
Phosphite, triisodecylphosphite, trilaurylphosphite, tris (tridecyl) phosphite, trioctadecylphosphite, tristearylphosphite, trioleylphosphite, phenyldiisodecylphosphite, diphenylisooctylphosphite, diphenyldecylphosphite Fight, diphenylisodecylphosphite, diphenyl (tridecyl) phosphite, triphenylphosphite, tris (nonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, diphenylnonylphenylphosphite, Di (nonylphenyl) dinonylphenyl phosphite and the like can be mentioned. Of these, preferred are tris (nonylphenyl) phosphite, di (nonylphenyl) dinonylphenylphosphite, and the like.

Next, the amine compound will be described.

Examples of amine compounds include compounds containing amino groups, such as alkylated phenyl-α-naphthylamine and alkylated diphenylamine having the following structures.

[0029]

[Chemical 3]

[R ₄₁ : hydrogen, a hydrocarbon group having 1 to 10 carbon atoms] [R ₄₂ : hydrogen, a hydrocarbon group having 1 to 18 carbon atoms, R ₄₃ : a hydrocarbon group having 1 to 18 carbon atoms] Examples thereof include octylphenyl-α-naphthylamine, phenyl-α-naphthylamine, and octylated diphenylamine. Among these, octylphenyl-α-naphthylamine and phenyl-α-naphthylamine are preferable.

Next, the hindered phenol will be described.

The hindered phenol of the component (3) used in the present invention preferably has the following structure and has an average (weight) molecular weight of 500 or more and 1200 or less, preferably 550 to 1200.

The hindered phenol of the component (4) usable in the present invention preferably has the following structure and has an average (weight) molecular weight of 300 or more and less than 500, preferably 350 to 450.

When the average molecular weight is less than 300, the heat resistance is insufficient, and when it exceeds 1200, the solubility is problematic.

[0035]

[Chemical 4]

[R ₅₁ : hydrogen or a hydrocarbon group having 1 to 4 carbon atoms, R ₅₂ :-(-CH _2- ) _1- (l is 1 to 5), R
_{53: -CH 2 -, R 54} : is a hydrocarbon group] Specifically C1-18 i) triethylene glycol-bis [3- (3-
t-butyl-4-hydroxy-5-methylphenyl) propionate], ii) triethyleneglycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate, iii) 1,6- Hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], iv) pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-
4-hydroxyphenyl) propionate], v) octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, vi) n-octyl-3-
(4-Hydroxy-3 ′, 5′-di-t-butylphenyl) propionate and the like can be mentioned. Particularly preferred is the combination formulation of i), iii), and vi).

The composition of the lubricating oil composition of the present invention has a heat resistant PAG lubricating oil (if added) to the PAG lubricating base oil, usually 100% by weight or less, preferably 5 to 4%.
Add 0% by weight. Furthermore, the phosphite is usually added to 0.
1 to 5.0% by weight, preferably 0.5 to 4.0% by weight. The amine compound is usually added in an amount of 0.1 to 4.0% by weight, preferably 0.5 to 3% by weight. The hindered phenol of the component (3) is usually added in an amount of 0.1 to 7.
0% by weight, preferably 2.0 to 5.0% by weight is added.

If the amount added is less than the above range, the effect is not sufficient. If the amount added is more than the above range, performance commensurate with the cost cannot be obtained. The compounding amounts of these three kinds of additives are (1) :( 2) :( 3) = 1: 0.05 to 0.7: 0.
5-5 are preferable.

When the hindered phenol of the component (4) is blended, the addition amount is 0.1 to 7.0% by weight, preferably 2.0 to 5.0% by weight. The compounding amount of the agent is (1) :( 2) :( 3) :( 4) = 1: 0.0
5 to 0.7: 0.5 to 5: 0.5 to 3 are preferable. Outside this range, heat, deterioration of oxidation stability, increase of sludge production, etc. occur.

If desired, the lubricating oil composition of the present invention may contain optional additives such as a rust preventive agent, a defoaming agent, a metal detergent, an antiwear agent and a pour point depressant.

[0041]

As is apparent from the following examples, the lubricating oil composition of the present invention has a synergistic effect due to the addition components.
It exhibits extremely excellent thermal oxidative stability compared to conventional products.

[0042]

EXAMPLES Examples 1-6, Comparative Examples 1-3 The following components (PAG 1,2,3, hindered phenols 1-5, aromatic amine 1, phosphite 1) are shown in the table below. Lubricating oil compositions according to the present invention (Examples 1 to 8) and compositions for comparison (Comparative Example 1) were compounded in a weight ratio.
~ 6) and were prepared.

25 g of each sample was weighed in a 50 cc beaker with or without the use of an iron catalyst in these compositions and left in a hot air circulation oven. Take out once a day and record weight loss and appearance. The sample loses weight as the deterioration progresses, and finally solidifies. The solidification time was investigated. The results are also shown in the table below. In addition,
This time represents the level of thermal oxidative stability of the composition, and the longer the time until solidification is, the more excellent the thermal oxidative stability of the composition is.

Regarding the evaluation of the amount of sludge produced, J
An IS K 2514 ISOT tester was used. 18
The test was carried out at 0 ° C. for 20 hours, and the pentane insoluble content of the oil after the test was judged as the amount of sludge produced.

From the table, it is apparent that the composition according to the present invention exhibits a long-term thermo-oxidative action and produces a small amount of sludge.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Chemical 5]

[0049]

[Chemical 6]

[0050]

[Chemical 7]

[0051]

[Chemical 8]

[0052]

[Chemical 9]

[0053]

[Chemical 10]

[0054]

[Chemical 11]

[0055]

[Chemical 12]

[0056]

[Chemical 13]

[0057]

[Chemical 14]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C10M 129: 10 129: 76) C10N 20:04 30:04 30:10 40:06

Claims (2)

[Claims] 1. A lubricating oil composition in which (1) a phosphite, (2) an amine compound, and (3) a hindered phenol having an average molecular weight of 500 or more and 1200 or less are mixed with a polyalkylene glycol-based lubricating base oil. 2. A lubricating oil composition comprising (4) a hindered phenol having an average molecular weight of 300 or more and less than 500, in addition to the lubricating oil composition of claim 1.