JP2005511815A - Mixture of three base oils and lubricating oil composition based thereon - Google Patents

Abstract

  The present invention describes a mixture of three base oil fluids (PAO, alkylated aromatics and aromatic esters). This synergistically improves solubility in industrial lubricating oil additives such as antioxidants and rust inhibitors, extreme pressure / antiwear agents, metal deactivators and the like. In addition to excellent hydrolytic stability, the mixture also has improved dispersibility and resistance to deposit formation without degrading the demulsibility.

Description

  The present invention relates to a lubricating base oil mixture. More particularly, the present invention relates to base stocks having unexpectedly improved resistance to deposit formation, improved solubility for lubricating oil additives and degradation products, and improved demulsibility.

  Synthetic lubricating base stocks prepared by oligomerizing one or more alpha olefins are well-known commercially available materials. It has a low pour point and a high viscosity index. Lubricating oil products using these poly-alpha-olefins (PAO) are typically more polar base oils such as alkylated aromatic fluids or polyol esters, or polyalkylene type additives, etc. Combined with seed dispersant.

  Inclusion of an alkylated aromatic group fluid, such as alkylated naphthalene, in the PAO group fluid provides a fluid mixture having improved hydrolytic stability. However, there is still a need to provide a mixture with improved dispersibility.

  Inclusion of a polyalkylene type additive in the PAO based fluid provides enhanced dispersibility. However, these additives form stable emulsions with water and degrade the hydrolytic stability of compositions using them. As a result, the use of the mixture is restricted to applications where water ingress is not a problem.

  Inclusion of the polyol ester in the PAO base fluid provides good dispersibility. However, insufficient hydrolytic stability is also provided.

  Accordingly, one object of the present invention is to provide a lubricating oil product that has improved dispersibility with good demulsibility and hydrolytic stability.

  Briefly, the present invention is a synergistic combination of synthetic fluids useful as a lubricating base stock mixture. This includes about 10 wt% or more of PAO fluid, about 1 wt% or more of alkylated aromatic fluid, and about 1 wt% or more of aromatic ester.

In a preferred embodiment, the lubricating base oil is based on the weight of the mixture
About 10 wt% to about 98 wt% PAO fluid;
From about 1 wt% to about 59 wt% alkylated aromatic, and from about 1 wt% to about 75 wt% aromatic ester.

  Advantageous features of the present invention will become apparent from the following detailed description.

  Applicants have found that a mixture of three lubricating base oil fluids (ie PAO, alkylated aromatics, and aromatic esters) can be used as a lubricant additive such as antioxidants and rust inhibitors, metal deactivators and the like. In contrast, it has been found to have improved solubility. The mixture also has improved hydrolytic stability, dispersibility, and resistance to deposit formation without degrading the demulsibility, making the mixture useful in a wide range of industrial applications. Furthermore, fully formulated lubricating oil compositions using the base oils of the present invention are particularly suitable for use in applications where water or moisture may enter. For example, oil used in combined cycle turbines, papermaking machines, rod mills and the like.

  The mixed base stock mixture of the present invention includes at least about 10 wt% PAO fluid. Generally, the mixture will contain from about 10 wt% to about 98 wt% PAO fluid, based on the total weight of the mixture. Preferably, the mixture comprises 60 wt% to 95 wt%, more preferably 80 wt% to 85 wt%.

PAO fluids and their preparation are well known in the art. Suitable those PAO practicing the present invention will be derived from C 2 _~ about C ₃₂ alpha-olefins. C ₈ to about C ₁₆ alpha olefins are preferred. Typically, the PAO will have a viscosity in the range of about 3 cSt to about 300 cSt (100 ° C.). The preferred PAO viscosity will, of course, depend on requirements such as the nature and amount of other ingredients used in the mixture and the intended end use of the lubricating base oil mixture.

  The base oil mixture of the present invention also contains alkylated aromatic compounds such as alkylated benzene, naphthalene, anthracene, biphenyl and the like. As with PAO, alkylated aromatics and their methods of preparation are well known in the art. Suitable alkylated aromatics are those having one or more short chain alkyl groups of 1 to about 8 carbon atoms. Preferred alkyl aromatics will have viscosities in the range of about 3 cSt to about 300 cSt (100 ° C.). The alkylated aromatic will be from about 1 to about 59 wt% of the total mixture. Preferably, it is about 5 wt% to about 35 wt%, more preferably about 10 wt%.

  The base stock mixture of the present invention also includes an aromatic ester fluid. Conventional lubricating oil-grade aromatic esters such as phthalate esters (mono and diesters), polyol esters, and end-containing esters containing S, N, and O suitable for the mixtures of the present invention are commercially available materials. It is. This is typically formed by reacting an organic acid or anhydride thereof with a linear or branched alcohol. These esters have viscosities in the range of about 4 cSt to about 30 cSt (100 ° C.). Generally, the amount of aromatic ester used in the base stock mixture will be from about 1 wt% to about 75 wt%, preferably from about 2 wt% to about 25 wt% of the total mixture. About 5 wt% to 8 wt% is more preferable.

  An advantageous feature of the base oil mixture of the present invention is its ability to solubilize additives such as heterocyclic rust inhibitors, antioxidants, antiwear agents, corrosion inhibitors and the like. Among the antioxidants suitable for use in the base stock mixture, particular mention is made of amine and phenol type antioxidants. Suitable antiwear agents include alkylated triphenyl phosphates, phosphorophites, diorganodithiocarbamates and the like.

  The following examples and comparative examples further illustrate many of the advantages of the present invention.

[Example 1]
In accordance with the present invention, a group comprising 84 wt% PAO (6 cSt @ 100 ° C.), 10 wt% alkyl aromatic (alkylated naphthalene) fluid (5 cSt @ 100 ° C.), and 6 wt% ester fluid (diisooctyl phthalate). A fully formulated lubricating oil composition (Formulation A) was prepared by using the base oil and mixing the base oil with the following additives. That is,
(1) hindered phenol and diphenylamine type antioxidant (1: 1) 0.4 wt%,
(2) Butylated triphenyl phosphate type antiwear agent 1.5 wt%, and (3) Ashless rust inhibitor 0.1 wt%
It is.
The composition was maintained at 100 ° C. for 16 weeks without any signs of cloudiness and aggregation. Cloudiness and agglomeration of course represent the insolubility of the additive.

  In contrast, a commercially available composition containing 6 cSt (100 ° C.) PAO, 20 wt% diisodecyl phthalate ester, and substantially the same amount of formulation A and similar types of additives, after 6 weeks, It was hazy and moderately aggregated.

  FIG. 1 illustrates the test results and shows the improved solubility that the base stocks of the present invention have for lubricating oil additives.

[Example 2]
The deposit control of the base oil of the present invention was compared with that of a commercially available lubricating oil composition (Comparative Example 2) by comparing Formulation A of Example 1 and Comparative Example 2 with Cincinnati Mechanical Oil Thermal Test A. The comparison was made by attaching to The composition of Comparative Example 2 had a PAO-based fluid, typical additives, and 1.0 wt% dispersant. The subject results are illustrated in FIG. As can be seen, under the subject conditions, Formulation A showed excellent low deposit formation. In addition, when the test was modified by increasing the test temperature from 275 ° F. to 350 ° F. after 168 hours, from the visual results of the sample, Formula A has much lower depositability. Was shown.

[Example 3]
The formulation A of Example 1 and a commercially available lubricating oil composition (Comparative Example 3) were subjected to the ASTM-D1401 demulsibility test. Comparative Example 3 was a PAO-based lubricating oil containing 1.0 wt% polyalkylene dispersant. The test results are shown in FIG.

  As can be seen, Formulation A using the base stock of the present invention showed complete water separability within 10 minutes. Formula A, of course, did not contain a demulsifier.

[Example 4]
This example demonstrates the oxidation and hydrolytic stability (measured by ASTM D943 TOST life test) of two base stocks (A and B) of the present invention with two other base stocks (C and Compare with D). Basestock A contained 80 wt% PAO (6 cSt @ 100 ° C.), 10 wt% alkylated naphthalene (5 cSt @ 100 ° C.), and 6 wt% ester fluid (diisooctyl phthalate). Base oil B was different from Formulation A in that the ester was a 50:50 mixture of ditridecyl phthalate and terephthalate ester.

  Base oils C and D used the same PAO as A and B. The alkylated aromatic fluid of C was the same as in A and B, while the ester of D was a trimellitate (trimellitic acid) ester.

  The test results are shown in FIG.

  As can be seen, A and B show a lifetime that is 30% longer than C.

FIG. 1 illustrates and compares the storage stability of commercial lubricating oil compositions with those using the base oil of the present invention. FIG. 2 illustrates the deposit suppression characteristics of the base oil of the present invention. FIG. 3 illustrates and compares the water demulsibility of a commercial composition with that of the base oil of the present invention. FIG. 4 illustrates and compares the oxidative and hydrolytic stability of the two base oil formulations of the present invention with the two others.

Claims (10)

Based on the weight of the mixture
10% by weight or more of a polyalphaolefin (PAO) fluid,
A lubricating base oil mixture comprising at least 1% by weight alkylated aromatic fluid and at least 1% by weight aromatic ester. 10% to 98% PAO fluid by weight,
The lubricating base oil mixture of claim 1 comprising 1 wt% to 59 wt% alkylated aromatic fluid, and 1 wt% to 75 wt% aromatic ester.   The lubricating base oil mixture of claim 2, wherein the PAO fluid comprises 80-85 wt%.   The lubricating base oil mixture of claim 2, wherein the alkylated aromatic fluid comprises 10 wt%.   The lubricating base oil mixture according to claim 2, wherein the aromatic ester is contained in an amount of 5 to 8% by weight.   The lubricating base oil mixture according to claim 1 or 2, wherein the alkylated aromatic fluid is an alkylated naphthalene having one or more alkyl groups of 1 to 8 carbon atoms.   The said aromatic ester is a product of a linear or branched aliphatic alcohol consisting of an aromatic acid or acid anhydride thereof and 3 to 18 carbon atoms. Lubricating base oil mixture.   The lubricating base oil mixture according to claim 7, wherein the aromatic acid or acid anhydride thereof is phthalic acid or acid anhydride thereof. A major amount of a lubricating base oil mixture, and at least one effective amount of a lubricating oil additive selected from the group consisting of antioxidants, rust inhibitors, extreme pressure agents and metal deactivators, wherein The lubricating base oil mixture comprises 10 wt% or more polyalphaolefin (PAO) fluid, 1 wt% or more alkylated aromatic fluid and 1 wt% or more aromatic ester, based on the weight of the mixture. A lubricating oil composition characterized by the above. The mixture is
10% to 98% PAO fluid by weight,
The lubricating oil composition of claim 9, comprising 1 wt% to 59 wt% alkylated aromatic fluid, and 1 wt% to 75 wt% aromatic ester.

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