WO2020160969A1

WO2020160969A1 - Lubricant composition

Info

Publication number: WO2020160969A1
Application number: PCT/EP2020/052104
Authority: WO
Inventors: Pascal Xanthopoulos
Original assignee: Polybridge
Priority date: 2019-02-04
Filing date: 2020-01-29
Publication date: 2020-08-13
Also published as: FR3092336A1; FR3092336B1; US20220127541A1; EP3921398A1

Abstract

The present invention relates to a lubricant composition comprising a base oil and an antioxidant additive, said antioxidant additive comprising a phenolic antioxidant, an amine antioxidant and a tocopherol supplement having at least one member of the list consisting of: beta-tocopherol, delta-tocopherol and gamma-tocopherol. The present invention also relates to a use of a lubricant composition according to the invention in a heat engine.

Description

Lubricating composition

The present invention relates to the field of lubricants. It relates more particularly to a lubricating composition for a heat engine.

Lubricants are commonly used in heat engines. In order to improve their hold over time, they generally include an antioxidant additive. The composition of the usual antioxidant additive is a mixture of phenolic antioxidant, and amine antioxidant.

The need to improve the resistance of lubricating compositions against heat degradation has existed since the advent of heat engines. However, the compositions of antioxidant packages intended for the formulation of lubricants and their performance have changed very little for more than 20 years.

Document WO2014134506 discloses lubricating compositions comprising antioxidants. However, the results obtained in terms of resistance over time are not satisfactory. Furthermore, this document proposes a combination of phenol and amine as an antioxidant, and proposes as an alternative a list of products, however without giving any technical effect associated with each product proposed, nor any indication to those skilled in the art on the benefits of either product.

An object of the present invention is to provide a lubricating composition having good thermal stability against oxidative degradation.

Another object of the present invention is to provide a lubricating composition whose impact on the environment is reduced.

The object of the present invention is to respond at least in part to the aforementioned objects by providing a lubricating composition with an improved antioxidant additive. To this end, it provides a lubricating composition comprising a base oil and an antioxidant additive, said antioxidant additive comprising a phenolic antioxidant, an antioxidant of amine type, and a tocopherol supplement comprising at least one element from the list consisting of: beta -tocopherol, delta-tocopherol and gamma-tocopherol.

Thanks to these arrangements, the composition according to the invention exhibits better thermal stability against oxidation degradation, compared with the compositions of the state of the art, while allowing a reduction in the proportion of antioxidant of amine type. , which is an advantage due to the toxicity of this product.

According to other characteristics:

the sum of the contents by weight of beta-tocopherol, delta-tocopherol and gamma-tocopherol in the tocopherol supplement may be greater than 50%, preferably greater than 70%, improving thermal stability against oxidative degradation of the lubricating composition,
the tocopherol supplement can consist of a mixture of several types of tocopherols, at a rate of 0 to 20% alpha-tocopherol, 0 to 5% beta-tocopherol, 50 to 65% gamma-tocopherol and 20 to 35% delta-tocopherol, which is a product with good results,
the tocopherol supplement may contain delta-tocopherol, which allows improved resistance over time of the lubricating composition,
the tocopherol supplement may have a delta-tocopherol content by weight greater than 50%, which further improves the thermal stability against oxidative degradation of the lubricating composition,
the content by weight of antioxidant additive can be between 0.5 and 1.5%, which is an effective embodiment of the invention,
the antioxidant additive may have a content by weight of tocopherol supplement of between 5 and 30%, which is an effective embodiment of the invention,
the antioxidant additive may exhibit a ratio of the weight contents of the amine-type antioxidant to the phenolic antioxidant of less than 0.9, preferably less than 0.8, which makes it possible to improve the toxicological profile of the composition lubricating,
The base oil can have a sulfur content of less than 0.03% by weight and a viscosity index greater than 120, which is an effective embodiment of the invention.

The present invention also relates to a use of a lubricating composition according to the invention, in a heat engine.

Thanks to these arrangements, the heat engine benefits from a composition which has improved durability over time compared to the compositions of the state of the art thanks to better thermal stability against oxidation degradation, while allowing reduction in the proportion of amine-type antioxidant, which is an advantage because of the toxicological risk that this product may represent.

The present invention will be better understood on reading the detailed description which follows, with reference to the appended figures in which:

is a graph showing the results of a series of comparative tests of a composition according to the invention,

is a graph showing a second aspect of the results of the series of comparative tests shown in FIG. 1.

The lubricating composition according to the invention comprises a base oil and an antioxidant additive. The lubricating composition may have an antioxidant additive content by weight of between 0.5 and 1.5%.

The base oil is preferably an oil from Group III, but can also be an oil from Group I, Group II, Group III +, Group IV or even Group V.

The antioxidant additive includes a phenolic antioxidant, an amine-type antioxidant, and a tocopherol supplement.

The antioxidant additive may have a tocopherol supplement by weight content of between 5 and 30%, preferably between 5 and 20%.

The phenolic antioxidant can be any phenolic compound, that is, a compound which has a free OH group attached to a phenyl ring, capable of being an antioxidant. As used herein, the term "phenolic antioxidant" also includes compounds where the OH group is attached to a phenyl ring, wherein the phenyl ring is part of a fused ring structure, for example, the phenyl ring is part of a ring structure. a benzothiophene ring, a naphthalene ring, an indole ring, a benzofuran ring or the like. Preferred phenolic antioxidants are hindered phenols (e.g., with at least one of the two ortho positions of the OH phenolic group substituted, e.g., by an alkyl group such as methyl, ethyl, propyl, cyclopropyl, isopropyl, butyl, isobutyl or tert-butyl) and dimeric phenols.

The phenolic antioxidant can therefore consist of a hindered phenol or of a mixture of several hindered phenols, chosen from 2,6-di-tert-butyl-4-methylphenol, 2-butyl-4,6-dimethylphenol. , 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 2,6-di-tert-butyl-4-isobutylphenol, 2 , 6-dicyclopentyl-4-methylphenol, 2- (α-methylcyclohexyl) -4,6-dimethylphenol, 2,6-dioctadecyl-4-methylphenol, 2,4,6-tricyclohexylphenol, 2,6-di -tert-butyl-4-methoxymethylphenol, 2,6-dinonyl-4-methylphenol, 2,4-dimethyl-6- (1'-methyl-undec-1'-yl) -phenol, 2,4- dimethyl-6- (1'-methylheptadec-1'-yl) -phenol, 2,4-dimethyl-6- (1'-methyltridec-1'-yl) -phenol, 2,4-diotylthiomethyl-6- tert-butylphenol, 2,4-diotylthiomethyl-6-methylphenol, 2,4-diotylthiomethyl-6-ethylphenol, and 2,6-didodecylthiomethyl-4-nonylphenol.

The amine antioxidant can be an aliphatic or aromatic amine.

Aromatic amine is a compound that has an amine group, whether it is a free amine group (eg, NH2), or a substituted amine group (eg, NR ¹ R ² , where R ¹ and R ² are independently hydrogen , alkyl, arylalkyl, heteroarylalkyl, cycloalkylalkyl, hétérocyclocycloalkyle, hétérocyclocycloalkyle, arylcycloalkyl, arylcycloalkyl, heteroarylcycloalkyl, arylhétérocycloalkyle, hétéroarylhétérocycloalkyle, hétéroarylhétérocycloalkyle, cycloalkyl, arylcycloalkyl, heteroarylcycloalkyl, heteroarylcycloalkyl, heterocycloalkyl, arylhétérocycloalkyle, alkenyl, arylalkenyl, cycloalkenyl, arylcycloalcène, heteroarylcycloalkenyl, heterocycloalkenyl, heterocycloalkenyl , arylheterocycloalkenyl, heteroarylheterocycloalkenyl, heteroarylheteroalkenyl, alkynyl, arylalkynyl, aryl, cycloalkylaryl, heterocycloalkylaryl, cycloalkenylaryl, heterocycloalkenyl, cycletoaryylheteroaryylheteroaryylheteroaryylheteroaryylheteroaryylheteroaryylheteroaryylheteroaryylheteroaryyl le), directly attached to an aromatic ring, such as a monocyclic aromatic ring (for example a phenyl ring, or a monocyclic heteroaromatic ring such as a thiophene ring, a pyridine ring, a pyrimidine ring, a furan ring, a ring pyrazine, a pyridazine ring, a triazine ring), or a polycyclic aromatic ring (for example a bicyclic aromatic ring such as a naphthalene ring, or a bicyclic heteroaromatic ring such as an indole ring, a benzofuran ring, a benzoimidazole ring or a benzothiophene ring, etc. or a tricyclic aromatic ring such as a carbazole).

The amine antioxidant can be an aromatic amine, wherein the amine group is bonded to two aromatic rings, such as two monocyclic aromatic rings (e.g., as described here) that are the same or different, two polycyclic aromatic rings (e.g. example, as described herein) which are the same or different, or a monocyclic aromatic ring (eg, as described here) and a polycyclic aromatic ring (eg, as described here). The amine antioxidant can be a diphenylamine. The amine antioxidant can further be an aromatic amine having the amine group attached to a monocyclic aromatic ring (eg, a phenyl ring) and a polycyclic aromatic ring (eg, a naphthalene ring). The amine antioxidant can be selected from the group consisting of dinonyl diphenylamine, butylated, octylated diphenylamine, dioctyl diphenylamine, Ν, Ν'-diisopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine , N, N'-bis (1,4-dimethylpentyl) -p-phenylenediamine, N, N'-bis (1-ethyl-3-methylpentyl) -p-phenylenediamine, N, N'-bis (1-methylheptyl) -p-phenylenediamine, N, N'-dicyclohexyl-p-phenylenediamine, N, N'-diphenyl-p-phenylenediamine, N, N'-di (naphth-2-yl) -p-phenylenediamine, N-isopropyl-N '-phenyl-p-phenylenediamine, N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, N- (1-methylheptyl) -N'-phenyl-p-phenylenediamine, N-cyclohexyl-N' -phenyl-N'-phenyl-p-phenylenediamine, 4- (p-toluenesulfonamido) -diphenylamine, N, N'-dimethyl-N, N'-di-sec-butyl-p-phenylenediamine, diphenylamine, diphenyl amine styrene ( CAS No. 68442-68-2), N-allyldiphenylamine, 4-isopropoxydiphenylamine, di (4-methoxyphenyl) amine, 2,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, N, N, N ', N'- tetramethyl-4,4'-dia minodiphenylmethane, 1,2-di [(2-methylphenyl) amino] -ethane, 1,2-di (phenylamino) propane, (o-tolyl) biguanide, di [4- (1 ', 3'-dimethylbutyl) phenyl] amine, tert-octylated N-phenyl-1-naphthylamine, phenyl-1-naphthylamine p-amine, p'-dioctyldiphenyl, mixture of tert-butyl-diphenylamines tert-butyl / tert-octyl mono- and di-alkyl, mixture of nonyldiphenylamines mono- and di-alkylated, mixture of mono- and di-alkylated dodecyldiphenylamines, mixture of mono- and di-alkylated isopropyl / isohexyl-diphenylamines, mixtures of mono- and di-alkylated tert-butyldiphenylamines, 2,3-dihydro-3 , 3-dimethyl-4H-1,4-benzothiazine, phenothiazine, mixture of mono- and di-alkylated tert-butyl / tert-octyl-phenothiazines, mixtures of mono- and di-alkylated tert-octylphenothiazines, N-allylphenothiazine and Ν , Ν, Ν ', Ν'-tetraphenyl-1,4-diaminobut-2-ene.

The tocopherol supplement comprises at least one of beta-tocopherol, delta-tocopherol and gamma-tocopherol.

The sum of the contents by weight of beta-tocopherol, gamma-tocopherol and delta-tocopherol in the tocopherol supplement can be greater than 50%, preferably greater than 70%.

Example of the composition of the tocopherol supplement according to the invention:

0 to 20% alpha-tocopherol,
0 to 5% beta-tocopherol,
50 to 65% gamma-tocopherol,
20 to 35% delta-tocopherol.

In a preferred embodiment of the invention, the tocopherol supplement comprises delta-tocopherol, preferably the content by weight of the tocopherol supplement in delta-tocopherol is greater than 50%.

The antioxidant additive may have a ratio of the amine antioxidant to phenolic antioxidant content by weight of between 0.6 and 1.2.

In a preferred embodiment, the ratio of the weight contents of the amine antioxidant to the phenolic antioxidant is less than 0.9, preferably less than 0.8. This is because the amine-type antioxidant can represent a toxicological risk, which is why it is advantageous to reduce its share in the antioxidant additive. This reduction is possible by the presence of the supplement tocopherol, which allows good antioxidant performance to be obtained while reducing the proportion of the amine-type antioxidant.

In a preferred embodiment of the invention, the base oil is a Group III oil, that is to say it has a sulfur content of less than 0.03% by weight and an index of viscosity greater than 120.

The lubricating composition according to the invention may also comprise one or more additional products chosen from the group consisting of an antiwear agent, a detergent, a metal deactivation additive, a phosphite, a lactone, a dispersant, a diluent, a emulsifier, defoamer, corrosion / rust inhibitor, extreme pressure agent, pour point depressant, viscosity index improver and friction modifier.

Example

A composition according to the invention was tested using a group III HC6 oil, to compare its performance with comparative compositions. A thermal aging test at 150 ° C. for 216 hours was carried out according to the CEC (“Coordinating European Council”) L-109-14 procedure.

The evolution of the viscosity KV100 (mm² / s) according to standard ASTM D445 / 446 as well as the resistance to oxidation (A / cm) according to standard DIN 51453 were measured at regular intervals during aging at 150 ° C. : t = 0 hours (initial), t = 72 hours, t = 144 hours, t = 168 hours, t = 216 hours.

The antioxidants tested are AO 1135, AO 5057, alpha-tocopherol, and a tocopherol supplement under the reference VB T70.

AO 1135 is a phenolic antioxidant with the composition: benzopropanoic acid, 3,5-bis (1,1-dimethyl-1,1-dimethylethyl) -4-hydroxy-, branched C7-9 alkyl esters.

AO 5057 is an amine antioxidant of composition: benzenamine, N-phenyl-, reaction products with 2,4,4-trimethylpentene.

VB T70 is a blend of antioxidants and sunflower oil, made up of:

30% sunflower oil
70% of tocopherols, among which are found:

9 to 20% alpha-tocopherol

1 to 4% beta-tocopherol

50 to 65% gamma-tocopherol,

20 to 35% delta-tocopherol.

Comparative compositions:

Composition A:

base oil HC6
Composition B:

99% HC6 base oil

1% AO 1135
Composition C:

99% HC6 base oil

0.7% AO 1135

0.3% VB170 (which corresponds to approximately 0.21% tocopherol supplement, due to the presence of sunflower oil in VB170)
Composition D (state of the art):

99% HC-6 base oil

0.5% AO 1135

0.5% AO 5057
Composition E:

99% HC-6 base oil

0.4% AO 1135

0.4% AO 5057

0.2% alpha-tocopherol

Example of a lubricating composition according to the invention:

Composition F:

98.9% HC6 base oil
0.45% AO 1135
0.45% AO 5057
0.2% VB 170 (corresponding to approximately 0.14% tocopherol supplement)

The results of the tests are given in Tables 1 and 2 below, as well as in Figures 1 and 2.

Table 1: Viscosity KV100 according to standards ASTM D445 / 446 (mm² / s)
Table 2: Oxidation (A / cm) according to DIN 51543

Durée de vieillissement à 150°C (heures)Aging time at 150 ° C (hours)	00	7272	144144	168168	216216
Composition AComposition A	6,3656.365	8,2588.258	11,5411.54	13,4513.45	19,8719.87
Composition BComposition B	6,3486.348	7,4757.475	9,9569.956	11,1411.14	14,5714.57
Composition CComposition C	6,3516.351	7,5037.503	10,0410.04	11,3711.37	15,2115.21
Composition DComposition D	6,3486.348	6,9626.962	9,3579.357	10,4310.43	13,5913.59
Composition EComposition E	6,3586.358	7,5317,531	10,4610.46	1212	17,0617.06
Composition FComposition F	6,3546.354	7,1987.198	8,8678.867	9,5959.595	11,411.4

Durée de vieillissement à 150°C (heures)Aging time at 150 ° C (hours)	7272	144144	168168	216216
Composition AComposition A	79,379.3	128,6128.6	144,6144.6	173,9173.9
Composition BComposition B	47,147.1	104,6104.6	118,5118.5	144,2144.2
Composition CComposition C	48,248.2	110,6110.6	126,1126.1	156,9156.9
Composition DComposition D	29,529.5	102,4102.4	120,9120.9	157157
Composition EComposition E	50,450.4	119,3119.3	138,2138.2	174,6174.6
Composition FComposition F	36,536.5	8787	99,599.5	123,2123.2

The graph in Figure 1 and Table 1 show the evolution of the viscosity of the oil during its thermal aging, measured according to the ASTM D445 / D446 protocols. The unit on the ordinate is mm ² / s. The unit of time on the abscissa is the duration of thermal aging at 150 ° C., expressed in hours. This test is particularly relevant for evaluating the performance of a lubricating composition and its resistance over time.

The graph in Figure 2 and Table 2 show the evolution of oxidation, measured according to the DIN 51453 protocol. The unit on the ordinate is A / cm. The unit of time on the abscissa is the duration of thermal aging at 150 ° C, expressed in hours.

In fig. 1 and 2, we see that the performance is the lowest for composition A, which does not contain an antioxidant additive.

Composition D, which is the benchmark antioxidant formulation used on a large scale in the lubricants market, is the state of the art composition that achieves the best performance in terms of viscosity (Fig. 1). Composition F, produced according to the invention, is similar to composition D with part of the antioxidants replaced by a mixture of alpha, beta, gamma and delta type tocopherols.

The results of composition F are better in terms of viscosity (fig. 1) and oxidation (fig. 2) than those of composition D. The comparison of compositions D and F makes it possible to conclude that an improvement in performance obtained by the presence of tocopherols.

Composition E is also similar to composition D, but this time with the presence of exclusively alpha-type tocopherols.

The performance of composition E shown in FIGS. 1 and 2 are worse than composition F, and even worse than composition D. The performance improvement effect observed previously is therefore not present with exclusively alpha type tocopherols, which shows the importance beta, gamma and delta type tocopherols.

Composition B includes only one phenolic antioxidant, and Composition C is similar to Composition B with part of the phenolic antioxidant replaced by the mixture of alpha, beta, gamma and delta tocopherols.

The performance of composition C shown in FIGS. 1 and 2 are worse than composition B. The performance enhancing effect observed previously with tocopherols is therefore not present in the absence of an amine-type antioxidant. This shows an effect of regeneration of the amine-type antioxidant by tocopherols, explaining that tocopherols improve the performance in composition F.

Therefore, in the compositions according to the invention it is possible to reduce the amount of antioxidant of amine type compared to the state of the art by adding a little tocopherol of beta, gamma or delta type, which is a benefit due to the toxicity of amine-type antioxidants. For example, we can provide an antioxidant with 50% phenol antioxidant, 40% amine antioxidant, and 10% tocopherol supplement, or 45% phenol antioxidant, 40% amine antioxidant, and 15% supplement tocopherol.

Although the above description is based on particular embodiments, it is in no way limiting the scope of the invention, and modifications can be made, in particular by substitution of technical equivalents or by a different combination of any. or part of the characteristics developed above.

Claims

Lubricating composition comprising a base oil and an antioxidant additive, in which:

the antioxidant additive content by weight is between 0.5 and 1.5%,

said antioxidant additive comprises a phenolic antioxidant, an amine-type antioxidant, and a tocopherol supplement,

the antioxidant additive has a content by weight of additional tocopherol of between 5 and 30%,

the tocopherol supplement contains at least one element from the list consisting of: beta-tocopherol, delta-tocopherol and gamma-tocopherol,

the sum of the contents by weight of beta-tocopherol, delta-tocopherol and gamma-tocopherol in the tocopherol supplement is greater than 50%.
A lubricating composition according to claim 1, in which the sum of the contents by weight of beta-tocopherol, delta-tocopherol and gamma-tocopherol in the tocopherol supplement is greater than 70%.
Lubricating composition according to the preceding claim, in which the tocopherol supplement consists of a mixture of several types of tocopherols, in a proportion of 0 to 20% of alpha-tocopherol, 0 to 5% of beta-tocopherol, 50 to 65% of gamma-tocopherol and 20 to 35% delta-tocopherol.
A lubricating composition according to one of claims 1 to 2, in which the tocopherol supplement comprises delta-tocopherol.
A lubricating composition according to claim 4, wherein the tocopherol supplement has a delta-tocopherol content by weight of greater than 50%.
A lubricating composition according to one of the preceding claims, wherein the antioxidant additive has a ratio of the weight contents of the amine antioxidant to the phenolic antioxidant of less than 0.9, preferably less than 0.8.
A lubricating composition according to one of the preceding claims, in which the base oil has a sulfur content of less than 0.03% by weight and a viscosity index of more than 120.
Use of a lubricating composition according to one of the preceding claims, in a heat engine.